Conifer species adapt to low-rainfall climates by following one of two divergent pathways.

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Brodribb, Timothy J; McAdam, Scott A M; Jordan, Gregory J; Martins, Samuel C V

2014-10-07

Water stress is one of the primary selective forces in plant evolution. There are characters often cited as adaptations to water stress, but links between the function of these traits and adaptation to drying climates are tenuous. Here we combine distributional, climatic, and physiological evidence from 42 species of conifers to show that the evolution of drought resistance follows two distinct pathways, both involving the coordinated evolution of tissues regulating water supply (xylem) and water loss (stomatal pores) in leaves. Only species with very efficient stomatal closure, and hence low minimum rates of water loss, inhabit dry habitats, but species diverged in their apparent mechanism for maintaining closed stomata during drought. An ancestral mechanism found in Pinaceae and Araucariaceae species relies on high levels of the hormone abscisic acid (ABA) to close stomata during water stress. A second mechanism, found in the majority of Cupressaceae species, uses leaf desiccation rather than high ABA levels to close stomata during sustained water stress. Species in the latter group were characterized by xylem tissues with extreme resistance to embolism but low levels of foliar ABA after 30 d without water. The combination of low levels of ABA under stress with cavitation-resistant xylem enables these species to prolong stomatal opening during drought, potentially extending their photosynthetic activity between rainfall events. Our data demonstrate a surprising simplicity in the way conifers evolved to cope with water shortage, indicating a critical interaction between xylem and stomatal tissues during the process of evolution to dry climates.

Resin duct characteristics in the wood of fire-scarred North American conifers

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Estelle Arbellay; Markus Stoffel; Elaine K. Sutherland; Kevin T. Smith; Donald A. Falk

2013-01-01

Traumatic resin ducts form in xylem and phloem tissue of conifers in response to abiotic wounding, fungal invasion, and insect attack. Little is known about resin duct characteristics in the wood of fire-scarred trees. The aim of this study is to quantify changes in traits of both axial and radial resin ducts, along with those of associated epithelial cells and...

Robustness of xylem properties in conifers: analyses of tracheid and pit dimensions along elevational transects.

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Losso, Adriano; Anfodillo, Tommaso; Ganthaler, Andrea; Kofler, Werner; Markl, Yvonne; Nardini, Andrea; Oberhuber, Walter; Purin, Gerhard; Mayr, Stefan

2018-02-01

In alpine regions, tree hydraulics are limited by low temperatures that restrict xylem growth and induce winter frost drought and freezing stress. While several studies have dealt with functional limitations, data on elevational changes in functionally relevant xylem anatomical parameters are still scarce. In wood cores of Pinus cembra L. and Picea abies (L.) Karst. trunks, harvested along five elevational transects, xylem anatomical parameters (tracheid hydraulic diameter dh, wall reinforcement (t/b)2), pit dimensions (pit aperture Da, pit membrane Dm and torus Dt diameters) and respective functional indices (torus overlap O, margo flexibility) were measured. In both species, tracheid diameters decreased and (t/b)2 increased with increasing elevation, while pit dimensions and functional indices remained rather constant (P. cembra: Dt 10.3 ± 0.2 μm, O 0.477 ± 0.005; P. abies: Dt 9.30 ± 0.18 μm, O 0.492 ± 0.005). However, dh increased with tree height following a power trajectory with an exponent of 0.21, and also pit dimensions increased with tree height (exponents: Dm 0.18; Dt 0.14; Da 0.11). Observed elevational trends in xylem structures were predominantly determined by changes in tree size. Tree height-related changes in anatomical traits showed a remarkable robustness, regardless of the distributional ranges of study species. Despite increasing stress intensities towards the timberline, no adjustment in hydraulic safety at the pit level was observed. © The Author(s) 2018. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Golgi enrichment and proteomic analysis of developing Pinus radiata xylem by free-flow electrophoresis.

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Harriet T Parsons

Full Text Available Our understanding of the contribution of Golgi proteins to cell wall and wood formation in any woody plant species is limited. Currently, little Golgi proteomics data exists for wood-forming tissues. In this study, we attempted to address this issue by generating and analyzing Golgi-enriched membrane preparations from developing xylem of compression wood from the conifer Pinus radiata. Developing xylem samples from 3-year-old pine trees were harvested for this purpose at a time of active growth and subjected to a combination of density centrifugation followed by free flow electrophoresis, a surface charge separation technique used in the enrichment of Golgi membranes. This combination of techniques was successful in achieving an approximately 200-fold increase in the activity of the Golgi marker galactan synthase and represents a significant improvement for proteomic analyses of the Golgi from conifers. A total of thirty known Golgi proteins were identified by mass spectrometry including glycosyltransferases from gene families involved in glucomannan and glucuronoxylan biosynthesis. The free flow electrophoresis fractions of enriched Golgi were highly abundant in structural proteins (actin and tubulin indicating a role for the cytoskeleton during compression wood formation. The mass spectrometry proteomics data associated with this study have been deposited to the ProteomeXchange with identifier PXD000557.

Influence of Drought on the Hydraulic Efficiency and the Hydraulic Safety of the Xylem - Case of a Semi-arid Conifer.

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Gentine, P.; Guerin, M. F.; von Arx, G.; Martin-Benito, D.; Griffin, K. L.; McDowell, N.; Pockman, W.; Andreu-Hayles, L.

2017-12-01

Recent droughts in the Southwest US have resulted in extensive mortality in the pinion pine population (Pinus Edulis). An important factor for resiliency is the ability of a plant to maintain a functional continuum between soil and leaves, allowing water's motion to be sustained or resumed. During droughts, loss of functional tracheids happens through embolism, which can be partially mitigated by increasing the hydraulic safety of the xylem. However, higher hydraulic safety is usually achieved by building narrower tracheids with thicker walls, resulting in a reduction of the hydraulic efficiency of the xylem (conductivity per unit area). Reduced efficiency constrains water transport, limits photosynthesis and might delay recovery after the drought. Supporting existing research on safety-efficiency tradeoff, we test the hypothesis that under dry conditions, isohydric pinions grow xylem that favor efficiency over safety. Using a seven-year experiment with three watering treatments (drought, control, irrigated) in New Mexico, we investigate the effect of drought on the xylem anatomy of pinions' branches. We also compare the treatment effect with interannual variations in xylem structure. We measure anatomical variables - conductivities, cell wall thicknesses, hydraulic diameter, cell reinforcement and density - and preliminarily conclude that treatment has little effect on hydraulic efficiency while hydraulic safety is significantly reduced under dry conditions. Taking advantage of an extremely dry year occurrence during the experiment, we find a sharp increase in vulnerability for xylem tissues built the same year.

Contrasting trait syndromes in angiosperms and conifers are associated with different responses of tree growth to temperature on a large scale.

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Carnicer, Jofre; Barbeta, Adrià; Sperlich, Dominik; Coll, Marta; Peñuelas, Josep

2013-01-01

Recent large-scale studies of tree growth in the Iberian Peninsula reported contrasting positive and negative effects of temperature in Mediterranean angiosperms and conifers. Here we review the different hypotheses that may explain these trends and propose that the observed contrasting responses of tree growth to temperature in this region could be associated with a continuum of trait differences between angiosperms and conifers. Angiosperm and conifer trees differ in the effects of phenology in their productivity, in their growth allometry, and in their sensitivity to competition. Moreover, angiosperms and conifers significantly differ in hydraulic safety margins, sensitivity of stomatal conductance to vapor-pressure deficit (VPD), xylem recovery capacity or the rate of carbon transfer. These differences could be explained by key features of the xylem such as non-structural carbohydrate content (NSC), wood parenchymal fraction or wood capacitance. We suggest that the reviewed trait differences define two contrasting ecophysiological strategies that may determine qualitatively different growth responses to increased temperature and drought. Improved reciprocal common garden experiments along altitudinal or latitudinal gradients would be key to quantify the relative importance of the different hypotheses reviewed. Finally, we show that warming impacts in this area occur in an ecological context characterized by the advance of forest succession and increased dominance of angiosperm trees over extensive areas. In this context, we examined the empirical relationships between the responses of tree growth to temperature and hydraulic safety margins in angiosperm and coniferous trees. Our findings suggest a future scenario in Mediterranean forests characterized by contrasting demographic responses in conifer and angiosperm trees to both temperature and forest succession, with increased dominance of angiosperm trees, and particularly negative impacts in pines.

Contrasting trait syndromes in angiosperms and conifers are associated with different responses of tree growth to temperature on a large scale.

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Jofre eCarnicer

2013-10-01

Full Text Available Recent large-scale studies of tree growth in the Iberian Peninsula reported contrasting positive and negative effects of temperature in Mediterranean angiosperms and conifers. Here we review the different hypotheses that may explain these trends and propose that the observed contrasting responses of tree growth to temperature in this region could be associated with a continuum of trait differences between angiosperms and conifers. Angiosperm and conifer trees differ in the effects of phenology in their productivity, in their growth allometry, and in their sensitivity to competition. Moreover, angiosperms and conifers significantly differ in hydraulic safety margins, sensitivity of stomatal conductance to vapor-pressure deficit, xylem recovery capacity or the rate of carbon transfer. These differences could be explained by key features of the xylem such as non-structural carbohydrate content (NSC, wood parenchymal fraction or wood capacitance. We suggest that the reviewed trait differences define two contrasting ecophysiological strategies that may determine qualitatively different growth responses to increased temperature and drought. Improved reciprocal common garden experiments along altitudinal or latitudinal gradients would be key to quantify the relative importance of the different hypotheses reviewed. Finally, we show that warming impacts in this area occur in an ecological context characterized by the advance of forest succession and increased dominance of angiosperm trees over extensive areas. In this context, we examined the empirical relationships between the responses of tree growth to temperature and hydraulic safety margins in angiosperm and coniferous trees. Our findings suggest a future scenario in Mediterranean forests characterized by contrasting demographic responses in conifer and angiosperm trees to both temperature and forest succession, with increased dominance of angiosperm trees, and particularly negative impacts in pines.

Xylem sap proteomics.

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de Bernonville, Thomas Dugé; Albenne, Cécile; Arlat, Matthieu; Hoffmann, Laurent; Lauber, Emmanuelle; Jamet, Elisabeth

2014-01-01

Proteomic analysis of xylem sap has recently become a major field of interest to understand several biological questions related to plant development and responses to environmental clues. The xylem sap appears as a dynamic fluid undergoing changes in its proteome upon abiotic and biotic stresses. Unlike cell compartments which are amenable to purification in sufficient amount prior to proteomic analysis, the xylem sap has to be collected in particular conditions to avoid contamination by intracellular proteins and to obtain enough material. A model plant like Arabidopsis thaliana is not suitable for such an analysis because efficient harvesting of xylem sap is difficult. The analysis of the xylem sap proteome also requires specific procedures to concentrate proteins and to focus on proteins predicted to be secreted. Indeed, xylem sap proteins appear to be synthesized and secreted in the root stele or to originate from dying differentiated xylem cells. This chapter describes protocols to collect xylem sap from Brassica species and to prepare total and N-glycoprotein extracts for identification of proteins by mass spectrometry analyses and bioinformatics.

Xylem traits, leaf longevity and growth phenology predict growth and mortality response to defoliation in northern temperate forests.

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Foster, Jane R

2017-09-01

Defoliation outbreaks are biological disturbances that alter tree growth and mortality in temperate forests. Trees respond to defoliation in many ways; some recover rapidly, while others decline gradually or die. Functional traits such as xylem anatomy, growth phenology or non-structural carbohydrate (NSC) storage could explain these responses, but idiosyncratic measures used by defoliation studies have frustrated efforts to generalize among species. Here, I test for functional differences with published growth and mortality data from 37 studies, including 24 tree species and 11 defoliators from North America and Eurasia. I synthesized data into standardized variables suitable for numerical models and used linear mixed-effects models to test the hypotheses that responses to defoliation vary among species and functional groups. Standardized data show that defoliation responses vary in shape and degree. Growth decreased linearly or curvilinearly, least in ring-porous Quercus and deciduous conifers (by 10-40% per 100% defoliation), whereas growth of diffuse-porous hardwoods and evergreen conifers declined by 40-100%. Mortality increased exponentially with defoliation, most rapidly for evergreen conifers, then diffuse-porous, then ring-porous species and deciduous conifers (Larix). Goodness-of-fit for functional-group models was strong (R2c = 0.61-0.88), if lower than species-specific mixed-models (R2c = 0.77-0.93), providing useful alternatives when species data are lacking. These responses are consistent with functional differences in leaf longevity, wood growth phenology and NSC storage. When defoliator activity lags behind wood-growth, either because xylem-growth precedes budburst (Quercus) or defoliator activity peaks later (sawflies on Larix), impacts on annual wood-growth will always be lower. Wood-growth phenology of diffuse-porous species and evergreen conifers coincides with defoliation and responds more drastically, and lower axial NSC storage makes them

The dynamic pipeline: hydraulic capacitance and xylem hydraulic safety in four tall conifer species

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Katherine A. McCulloh; Daniel M. Johnson; Frederick C. Meinzer; David R. Woodruff

2013-01-01

Recent work has suggested that plants differ in their relative reliance on structural avoidance of embolism versus maintenance of the xylem water column through dynamic traits such as capacitance, but we still know little about how and why species differ along this continuum. It is even less clear how or if different parts of a plant vary along this spectrum. Here we...

Arsenate impact on the metabolite profile, production and arsenic loading of xylem sap in cucumbers (Cucumis sativus L.

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Kalle eUroic

2012-04-01

Full Text Available Arsenic uptake and translocation studies on xylem sap focus generally on the concentration and speciation of arsenic in the xylem. Arsenic impact on the xylem sap metabolite profile and its production during short term exposure has not been reported in detail. To investigate this, cucumbers were grown hydroponically and arsenate (AsV and DMA were used for plant treatment for 24 h. Total arsenic and arsenic speciation in xylem sap was analysed including a metabolite profiling under arsenate stress. Produced xylem sap was quantified and absolute arsenic transported was determined. AsV exposure has a significant impact on the metabolite profile of xylem sap. Four m/z values corresponding to four compounds were up regulated, one compound down regulated by arsenate exposure. The compound down regulated was identified to be isoleucine. Furthermore, arsenate has a significant influence on sap production, leading to a reduction of up to 96 % sap production when plants are exposed to 1000 μg kg-1 arsenate. No difference to control plants was observed when plants were exposed to 1000 μg kg-1 DMA. Absolute arsenic amount in xylem sap was the lowest at high arsenate exposure. These results show that AsV has a significant impact on the production and metabolite profile of xylem sap. The physiological importance of isoleucine needs further attention.

Arsenate Impact on the Metabolite Profile, Production, and Arsenic Loading of Xylem Sap in Cucumbers (Cucumis sativus L.)

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Uroic, M. Kalle; Salaün, Pascal; Raab, Andrea; Feldmann, Jörg

2012-01-01

Arsenic uptake and translocation studies on xylem sap focus generally on the concentration and speciation of arsenic in the xylem. Arsenic impact on the xylem sap metabolite profile and its production during short term exposure has not been reported in detail. To investigate this, cucumbers were grown hydroponically and arsenate (AsV) and DMA were used for plant treatment for 24 h. Total arsenic and arsenic speciation in xylem sap was analyzed including a metabolite profiling under AsV stress. Produced xylem sap was quantified and absolute arsenic transported was determined. AsV exposure had a significant impact on the metabolite profile of xylem sap. Four m/z values corresponding to four compounds were up-regulated, one compound down-regulated by AsV exposure. The compound down-regulated was identified to be isoleucine. Furthermore, AsV exposure had a significant influence on sap production, leading to a reduction of up to 96% sap production when plants were exposed to 1000 μg kg−1 AsV. No difference to control plants was observed when plants were exposed to 1000 μg kg−1 DMA. Absolute arsenic amount in xylem sap was the lowest at high AsV exposure. These results show that AsV has a significant impact on the production and metabolite profile of xylem sap. The physiological importance of isoleucine needs further attention. PMID:22536187

Xylem resistance to embolism: presenting a simple diagnostic test for the open vessel artefact.

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Torres-Ruiz, José M; Cochard, Hervé; Choat, Brendan; Jansen, Steven; López, Rosana; Tomášková, Ivana; Padilla-Díaz, Carmen M; Badel, Eric; Burlett, Regis; King, Andrew; Lenoir, Nicolas; Martin-StPaul, Nicolas K; Delzon, Sylvain

2017-07-01

Xylem vulnerability to embolism represents an essential trait for the evaluation of the impact of hydraulics in plant function and ecology. The standard centrifuge technique is widely used for the construction of vulnerability curves, although its accuracy when applied to species with long vessels remains under debate. We developed a simple diagnostic test to determine whether the open-vessel artefact influences centrifuge estimates of embolism resistance. Xylem samples from three species with differing vessel lengths were exposed to less negative xylem pressures via centrifugation than the minimum pressure the sample had previously experienced. Additional calibration was obtained from non-invasive measurement of embolism on intact olive plants by X-ray microtomography. Results showed artefactual decreases in hydraulic conductance (k) for samples with open vessels when exposed to a less negative xylem pressure than the minimum pressure they had previously experienced. X-Ray microtomography indicated that most of the embolism formation in olive occurs at xylem pressures below -4.0 MPa, reaching 50% loss of hydraulic conductivity at -5.3 MPa. The artefactual reductions in k induced by centrifugation underestimate embolism resistance data of species with long vessels. A simple test is suggested to avoid this open vessel artefact and to ensure the reliability of this technique in future studies. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

Lead mobility within the xylem of red spruce seedlings: Implications for the development of pollution histories

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John R. Donnelly; John B. Shane; Paul G. Schaberg

1990-01-01

Development of Pb pollution histories using tree ring analyses has been troubled by possible mobility of Pb within stem xylem. In a 2-yr study, we exposed red spruce (Picea rubens Sarg.) seedlings to Pb during one growing season, with Pb excluded in either the previous or following growing season. Lead levels within xylem rings and bark were...

A synchronous increase in hydraulic conductive capacity and mechanical support in conifers with relatively uniform xylem structure.

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Jagels, Richard; Visscher, George E

2006-02-01

The dual function provided by longitudinal tracheids in conifers has led to a generally held trade-off concept that increasing wall thickness and/or volume of latewood tracheids improves mechanical support, while increasing cell diameter and/or volume of earlywood tracheids enhances conductive potential. Yet, some conifers have either uniform cell structure across the growth ring or, at most, a small amount of latewood. How do these trees accomplish the needs for increasing support and conduction with height growth? We examined Metasequoia glyptostroboides, a species that we previously demonstrated improves its mechanical properties with increasing age without a change in specific gravity or secondary wall microfibril angle. In this paper, we showed that lignin and extractive contents are not contributing factors, and through composite structure analysis, we eliminated a role for tracheid length. Using micromorphometric analysis, we demonstrated that as cell diameter increases, total primary wall decreases, secondary wall increases, and strength and conductive capacity increase with no change in specific gravity. Meta-analysis using other species of Cupressaceae, Podocarpaceae, and Araucariaceae provided strong corroborative evidence for this design strategy.

Tracheid diameter is the key trait determining the extent of freezing-induced embolism in conifers.

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Pittermann, Jarmila; Sperry, John

2003-09-01

We tested the hypotheses that freezing-induced embolism is related to conduit diameter, and that conifers and angiosperms with conduits of equivalent diameter will exhibit similar losses of hydraulic conductivity in response to freezing. We surveyed the freeze-thaw response of conifers with a broad range of tracheid diameters by subjecting wood segments (root, stem and trunk wood) to a freeze-thaw cycle at -0.5 MPa in a centrifuge. Embolism increased as mean tracheid diameter exceeded 30 microm. Tracheids with a critical diameter greater than 43 microm were calculated to embolize in response to freezing and thawing at a xylem pressure of -0.5 MPa. To confirm that freezing-induced embolism is a function of conduit air content, we air-saturated stems of Abies lasiocarpa (Hook.) Nutt. (mean conduit diameter 13.7 +/- 0.7 microm) by pressurizing them 1 to 60 times above atmospheric pressure, prior to freezing and thawing. The air saturation method simulated the effect of increased tracheid size because the degree of super-saturation is proportional to a tracheid volume holding an equivalent amount of dissolved air at ambient pressure. Embolism increased when the dissolved air content was equivalent to a mean tracheid diameter of 30 microm at ambient air pressure. Our centrifuge and air-saturation data show that conifers are as vulnerable to freeze-thaw embolism as angiosperms with equal conduit diameter. We suggest that the hydraulic conductivity of conifer wood is maximized by increasing tracheid diameters in locations where freezing is rare. Conversely, the narrowing of tracheid diameters protects against freezing-induced embolism in cold climates.

Cell size and wall dimensions drive distinct variability of earlywood and latewood density in Northern Hemisphere conifers.

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Björklund, Jesper; Seftigen, Kristina; Schweingruber, Fritz; Fonti, Patrick; von Arx, Georg; Bryukhanova, Marina V; Cuny, Henri E; Carrer, Marco; Castagneri, Daniele; Frank, David C

2017-11-01

Interannual variability of wood density - an important plant functional trait and environmental proxy - in conifers is poorly understood. We therefore explored the anatomical basis of density. We hypothesized that earlywood density is determined by tracheid size and latewood density by wall dimensions, reflecting their different functional tasks. To determine general patterns of variability, density parameters from 27 species and 349 sites across the Northern Hemisphere were correlated to tree-ring width parameters and local climate. We performed the same analyses with density and width derived from anatomical data comprising two species and eight sites. The contributions of tracheid size and wall dimensions to density were disentangled with sensitivity analyses. Notably, correlations between density and width shifted from negative to positive moving from earlywood to latewood. Temperature responses of density varied intraseasonally in strength and sign. The sensitivity analyses revealed tracheid size as the main determinant of earlywood density, while wall dimensions become more influential for latewood density. Our novel approach of integrating detailed anatomical data with large-scale tree-ring data allowed us to contribute to an improved understanding of interannual variations of conifer growth and to illustrate how conifers balance investments in the competing xylem functions of hydraulics and mechanical support. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

Xylem formation can be modeled statistically as a function of primary growth and cambium activity.

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Huang, Jian-Guo; Deslauriers, Annie; Rossi, Sergio

2014-08-01

Primary (budburst, foliage and shoot) growth and secondary (cambium and xylem) growth of plants play a vital role in sequestering atmospheric carbon. However, their potential relationships have never been mathematically quantified and the underlying physiological mechanisms are unclear. We monitored primary and secondary growth in Picea mariana and Abies balsamea on a weekly basis from 2010 to 2013 at four sites over an altitudinal gradient (25-900 m) in the eastern Canadian boreal forest. We determined the timings of onset and termination through the fitted functions and their first derivative. We quantified the potential relationships between primary growth and secondary growth using the mixed-effects model. We found that xylem formation of boreal conifers can be modeled as a function of cambium activity, bud phenology, and shoot and needle growth, as well as species- and site-specific factors. Our model reveals that there may be an optimal mechanism to simultaneously allocate the photosynthetic products and stored nonstructural carbon to growth of different organs at different times in the growing season. This mathematical link can bridge phenological modeling, forest ecosystem productivity and carbon cycle modeling, which will certainly contribute to an improved prediction of ecosystem productivity and carbon equilibrium. © 2014 The Authors. New Phytologist © 2014 New Phytologist Trust.

Xylem hydraulic safety margins in woody plants: coordination of stomatal control of xylem tension with hydraulic capacitance

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Frederick C. Meinzer; Daniel M. Johnson; Barbara Lachenbruch; Katherine A. McCulloh; David R. Woodruff

2009-01-01

The xylem pressure inducing 50% loss of hydraulic conductivity due to embolism (P50) is widely used for comparisons of xylem vulnerability among species and across aridity gradients. However, despite its utility as an index of resistance to catastrophic xylem failure under extreme drought, P50 may have no special...

Beech (Fagus sylvatica L.) branches show acclimation of xylem anatomy and hydraulic properties to increased light after thinning

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Lemoine, D.; Jacquemin, S.; Granier, A.

2002-01-01

International audience; Hydraulic acclimation of Fagus sylvatica L. was analysed in response to forest thinning. Several months after thinning, leaf and xylem water potential and stomatal conductance of thinned branches were compared to sun-exposed and shade branches. We characterised vulnerability to cavitation for branches taken from these three treatments. We compared effect of thinning on xylem anatomy (mean vessel diameter, vessel density). Thinned branches exhibited higher stomatal cond...

Quantification of the xylem-to-phloem transfer of amino acids by use of inulin (14C)carboxylic acid as xylem transfer marker

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Van Bel, A.J.

1984-01-01

Inulin ( 14 C)carboxylic acid and 14 C-labelled amino acid (α-aminoisobutyric acid (aib) and valine) solutions were introduced into the transpiration stream through the cut stem bases of young (4-12 leaves) tomato plants. Inulin carboxylic acid (inu) was translocated exclusively by the xylem, whereas the amino acid distribution resulted from both xylem and phloem import. Comparison of the distribution of inu and aib permitted a quantitative assessment of the xylem-to-phloem transfer in the stem. Of aib, 20.6% traversed from xylem to phloem in a plant with 12 leaves. The phloem import was not evenly distributed over the leaves and varied from 0% (first five leaves) to 95% (top leaf) of the aib import per leaf. Doubling the flow rates in the xylem reduced the aib supply to 25% in the top leaf and 55% in the next leaf, which reflects a reduced xylem-to-phloem transfer. (author)

Mixed-Severity Fire Fosters Heterogeneous Spatial Patterns of Conifer Regeneration in a Dry Conifer Forest

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Sparkle L. Malone

2018-01-01

Full Text Available We examined spatial patterns of post-fire regenerating conifers in a Colorado, USA, dry conifer forest 11–12 years following the reintroduction of mixed-severity fire. We mapped and measured all post-fire regenerating conifers, as well as all other post-fire regenerating trees and all residual (i.e., surviving trees, in three 4-ha plots following the 2002 Hayman Fire. Residual tree density ranged from 167 to 197 trees ha−1 (TPH, and these trees were clustered at distances up to 30 m. Post-fire regenerating conifers, which ranged in density from 241 to 1036 TPH, were also clustered at distances up to at least 30 m. Moreover, residual tree locations drove post-fire regenerating conifer locations, with the two showing a pattern of repulsion. Topography and post-fire sprouting tree species locations further drove post-fire conifer regeneration locations. These results provide a foundation for anticipating how the reintroduction of mixed-severity fire may affect long-term forest structure, and also yield insights into how historical mixed-severity fire may have regulated the spatially heterogeneous conditions commonly described for pre-settlement dry conifer forests of Colorado and elsewhere.

A meta-analysis of cambium phenology and growth: linear and non-linear patterns in conifers of the northern hemisphere.

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Rossi, Sergio; Anfodillo, Tommaso; Cufar, Katarina; Cuny, Henri E; Deslauriers, Annie; Fonti, Patrick; Frank, David; Gricar, Jozica; Gruber, Andreas; King, Gregory M; Krause, Cornelia; Morin, Hubert; Oberhuber, Walter; Prislan, Peter; Rathgeber, Cyrille B K

2013-12-01

Ongoing global warming has been implicated in shifting phenological patterns such as the timing and duration of the growing season across a wide variety of ecosystems. Linear models are routinely used to extrapolate these observed shifts in phenology into the future and to estimate changes in associated ecosystem properties such as net primary productivity. Yet, in nature, linear relationships may be special cases. Biological processes frequently follow more complex, non-linear patterns according to limiting factors that generate shifts and discontinuities, or contain thresholds beyond which responses change abruptly. This study investigates to what extent cambium phenology is associated with xylem growth and differentiation across conifer species of the northern hemisphere. Xylem cell production is compared with the periods of cambial activity and cell differentiation assessed on a weekly time scale on histological sections of cambium and wood tissue collected from the stems of nine species in Canada and Europe over 1-9 years per site from 1998 to 2011. The dynamics of xylogenesis were surprisingly homogeneous among conifer species, although dispersions from the average were obviously observed. Within the range analysed, the relationships between the phenological timings were linear, with several slopes showing values close to or not statistically different from 1. The relationships between the phenological timings and cell production were distinctly non-linear, and involved an exponential pattern. The trees adjust their phenological timings according to linear patterns. Thus, shifts of one phenological phase are associated with synchronous and comparable shifts of the successive phases. However, small increases in the duration of xylogenesis could correspond to a substantial increase in cell production. The findings suggest that the length of the growing season and the resulting amount of growth could respond differently to changes in environmental conditions.

NorWood: a gene expression resource for evo-devo studies of conifer wood development.

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Jokipii-Lukkari, Soile; Sundell, David; Nilsson, Ove; Hvidsten, Torgeir R; Street, Nathaniel R; Tuominen, Hannele

2017-10-01

The secondary xylem of conifers is composed mainly of tracheids that differ anatomically and chemically from angiosperm xylem cells. There is currently no high-spatial-resolution data available profiling gene expression during wood formation for any coniferous species, which limits insight into tracheid development. RNA-sequencing data from replicated, high-spatial-resolution section series throughout the cambial and woody tissues of Picea abies were used to generate the NorWood.conGenIE.org web resource, which facilitates exploration of the associated gene expression profiles and co-expression networks. Integration within PlantGenIE.org enabled a comparative regulomics analysis, revealing divergent co-expression networks between P. abies and the two angiosperm species Arabidopsis thaliana and Populus tremula for the secondary cell wall (SCW) master regulator NAC Class IIB transcription factors. The SCW cellulose synthase genes (CesAs) were located in the neighbourhoods of the NAC factors in A. thaliana and P. tremula, but not in P. abies. The NorWood co-expression network enabled identification of potential SCW CesA regulators in P. abies. The NorWood web resource represents a powerful community tool for generating evo-devo insights into the divergence of wood formation between angiosperms and gymnosperms and for advancing understanding of the regulation of wood development in P. abies. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

Mixed-severity fire fosters heterogeneous spatial patterns of conifer regeneration in a dry conifer forest

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Sparkle L. Malone; Paula J. Fornwalt; Mike A. Battaglia; Marin E. Chambers; Jose M. Iniguez; Carolyn H. Sieg

2018-01-01

We examined spatial patterns of post-fire regenerating conifers in a Colorado, USA, dry conifer forest 11-12 years following the reintroduction of mixed-severity fire. We mapped and measured all post-fire regenerating conifers, as well as all other post-fire regenerating trees and all residual (i.e., surviving) trees, in three 4-ha plots following the 2002 Hayman Fire...

Ion-mediated changes of xylem hydraulic resistance in planta: fact or fiction?

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van Ieperen, Wim

2007-04-01

Although xylem provides an efficient transport pathway for water in plants, the hydraulic conductivity of xylem (K(h)) can still influence plant water status. For decades, the K(h) of functional xylem has been assumed to be constant in the short term because xylem consists of a network of dead interconnected capillary elements (conduits). Recent research has shown that K(h) can change in response to the cation content of the xylem fluid. Volume changes of pectin gel in nanometer-sized pores at inter-conduit connections are hypothesized to be the cause, and implications for xylem transport in planta are suggested. However, it seems too early to be conclusive about this phenomenon because the phenomenon has not been measured in planta with xylem fluids that realistically mimic natural xylem sap and the applied methods used to measure ion-mediated changes in K(h) have drawbacks.

Conifer R2R3-MYB transcription factors: sequence analyses and gene expression in wood-forming tissues of white spruce (Picea glauca

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Grima-Pettenati Jacqueline

2007-03-01

Full Text Available Abstract Background Several members of the R2R3-MYB family of transcription factors act as regulators of lignin and phenylpropanoid metabolism during wood formation in angiosperm and gymnosperm plants. The angiosperm Arabidopsis has over one hundred R2R3-MYBs genes; however, only a few members of this family have been discovered in gymnosperms. Results We isolated and characterised full-length cDNAs encoding R2R3-MYB genes from the gymnosperms white spruce, Picea glauca (13 sequences, and loblolly pine, Pinus taeda L. (five sequences. Sequence similarities and phylogenetic analyses placed the spruce and pine sequences in diverse subgroups of the large R2R3-MYB family, although several of the sequences clustered closely together. We searched the highly variable C-terminal region of diverse plant MYBs for conserved amino acid sequences and identified 20 motifs in the spruce MYBs, nine of which have not previously been reported and three of which are specific to conifers. The number and length of the introns in spruce MYB genes varied significantly, but their positions were well conserved relative to angiosperm MYB genes. Quantitative RTPCR of MYB genes transcript abundance in root and stem tissues revealed diverse expression patterns; three MYB genes were preferentially expressed in secondary xylem, whereas others were preferentially expressed in phloem or were ubiquitous. The MYB genes expressed in xylem, and three others, were up-regulated in the compression wood of leaning trees within 76 hours of induction. Conclusion Our survey of 18 conifer R2R3-MYB genes clearly showed a gene family structure similar to that of Arabidopsis. Three of the sequences are likely to play a role in lignin metabolism and/or wood formation in gymnosperm trees, including a close homolog of the loblolly pine PtMYB4, shown to regulate lignin biosynthesis in transgenic tobacco.

Ion-mediated changes of xylem hydraulic resistance in planta: fact or fiction?

NARCIS (Netherlands)

Ieperen, van W.

2007-01-01

Although xylem provides an efficient transport pathway for water in plants, the hydraulic conductivity of xylem (Kh) can still influence plant water status. For decades, the Kh of functional xylem has been assumed to be constant in the short term because xylem consists of a network of dead

Effects of combined drought and heavy metal stresses on xylem structure and hydraulic conductivity in red maple (Acer rubrum L.).

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de Silva, Nayana Dilini Gardiyehewa; Cholewa, Ewa; Ryser, Peter

2012-10-01

The effects of heavy metal stress, drought stress, and their combination on xylem structure in red maple (Acer rubrum) seedlings were investigated in an outdoor pot experiment. As metal-contaminated substrate, a mixture of 1.5% slag with sand was used, with Ni, Cu, Co, and Cr as the main contaminants. Plants grown on contaminated substrate had increased leaf metal concentrations. The two stresses reduced plant growth in an additive manner. The effects of metal and drought stresses on xylem characteristics were similar to each other, with a reduced proportion of xylem tissue, reduced conduit density in stems, and reduced conduit size in the roots. This resulted, in both stems and roots, in reductions in hydraulic conductance, xylem-specific conductivity, and leaf-specific conductivity. The similarity of the responses to the two stresses suggests that the plants' response to metals was actually a drought response, probably due to the reduced water uptake capacity of the metal-exposed roots. The only plant responses specific to metal stress were decreasing trends of stomatal density and chlorophyll content. In conclusion, the exposure to metals aggravates water stress in an additive manner, making the plants more vulnerable to drought.

Quantifying cambial activity of high-elevation conifers in the Great Basin, Nevada, USA

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Ziaco, E.; Biondi, F.; Rossi, S.; Deslauriers, A.

2013-12-01

Understanding the physiological mechanisms that control the formation of tree rings provides the necessary biological basis for developing dendroclimatic reconstructions and dendroecological histories. Studies of wood formation in the Great Basin are now being conducted in connection with the Nevada Climate-ecohydrological Assessment Network (NevCAN), a recently established transect of valley-to-mountaintop instrumented stations in the Snake and Sheep Ranges of the Great Basin. Automated sensors record meteorological, soil, and vegetational variables at these sites, providing unique opportunities for ecosystem science, and are being used to investigate the ecological implications of xylogenesis. We present here an initial study based on microcores collected during summer 2013 from mountain and subalpine conifers (including Great Basin bristlecone pine, Pinus longaeva) growing on the west slope of Mt. Washington. Samples were taken from the mountain west (SM; 2810 m elevation) and the subalpine west (SS, 3355 m elevation) NevCAN sites on June 16th and 27th, 2013. The SS site was further subdivided in a high (SSH) and a low (SSL) group of trees, separated by about 10 m in elevation. Microscopic analyses showed the effect of elevation on cambial activity, as annual ring formation was more advanced at the lower (mountain) site compared to the higher (subalpine) one. At all sites cambium size showed little variations between the two sampling dates. The number of xylem cells in the radial enlargement phase decreased between the two sampling dates at the mountain site but increased at the subalpine site, confirming a delayed formation of wood at the higher elevations. Despite relatively high within-site variability, a general trend of increasing number of cells in the lignification phase was found at all sites. Mature cells were present only at the mountain site on June 27th. Spatial differences in the xylem formation process emerged at the species level and, within

Water filtration using plant xylem.

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Michael S H Boutilier

Full Text Available Effective point-of-use devices for providing safe drinking water are urgently needed to reduce the global burden of waterborne disease. Here we show that plant xylem from the sapwood of coniferous trees--a readily available, inexpensive, biodegradable, and disposable material--can remove bacteria from water by simple pressure-driven filtration. Approximately 3 cm(3 of sapwood can filter water at the rate of several liters per day, sufficient to meet the clean drinking water needs of one person. The results demonstrate the potential of plant xylem to address the need for pathogen-free drinking water in developing countries and resource-limited settings.

Branch xylem density variations across the Amazon Basin

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Patiño, S.; Lloyd, J.; Paiva, R.; Baker, T. R.; Quesada, C. A.; Mercado, L. M.; Schmerler, J.; Schwarz, M.; Santos, A. J. B.; Aguilar, A.; Czimczik, C. I.; Gallo, J.; Horna, V.; Hoyos, E. J.; Jimenez, E. M.; Palomino, W.; Peacock, J.; Peña-Cruz, A.; Sarmiento, C.; Sota, A.; Turriago, J. D.; Villanueva, B.; Vitzthum, P.; Alvarez, E.; Arroyo, L.; Baraloto, C.; Bonal, D.; Chave, J.; Costa, A. C. L.; Herrera, R.; Higuchi, N.; Killeen, T.; Leal, E.; Luizão, F.; Meir, P.; Monteagudo, A.; Neil, D.; Núñez-Vargas, P.; Peñuela, M. C.; Pitman, N.; Priante Filho, N.; Prieto, A.; Panfil, S. N.; Rudas, A.; Salomão, R.; Silva, N.; Silveira, M.; Soares Dealmeida, S.; Torres-Lezama, A.; Vásquez-Martínez, R.; Vieira, I.; Malhi, Y.; Phillips, O. L.

2009-04-01

Xylem density is a physical property of wood that varies between individuals, species and environments. It reflects the physiological strategies of trees that lead to growth, survival and reproduction. Measurements of branch xylem density, ρx, were made for 1653 trees representing 598 species, sampled from 87 sites across the Amazon basin. Measured values ranged from 218 kg m-3 for a Cordia sagotii (Boraginaceae) from Mountagne de Tortue, French Guiana to 1130 kg m-3 for an Aiouea sp. (Lauraceae) from Caxiuana, Central Pará, Brazil. Analysis of variance showed significant differences in average ρx across regions and sampled plots as well as significant differences between families, genera and species. A partitioning of the total variance in the dataset showed that species identity (family, genera and species) accounted for 33% with environment (geographic location and plot) accounting for an additional 26%; the remaining "residual" variance accounted for 41% of the total variance. Variations in plot means, were, however, not only accountable by differences in species composition because xylem density of the most widely distributed species in our dataset varied systematically from plot to plot. Thus, as well as having a genetic component, branch xylem density is a plastic trait that, for any given species, varies according to where the tree is growing in a predictable manner. Within the analysed taxa, exceptions to this general rule seem to be pioneer species belonging for example to the Urticaceae whose branch xylem density is more constrained than most species sampled in this study. These patterns of variation of branch xylem density across Amazonia suggest a large functional diversity amongst Amazonian trees which is not well understood.

Comparing growth phenology of co-occurring deciduous and evergreen conifers exposed to drought.

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Swidrak, Irene; Schuster, Roman; Oberhuber, Walter

2013-12-01

might indicate sink competition for carbohydrates to belowground organs. This is supported by completion of apical growth in mid June in all species, except for needle growth of Pinus sylvestris , which lasted until early August. Phenological observations of conifers exposed to drought revealed that tree water status early during the growing season determines total annual aboveground growth and besides temperature, species-specific endogenous and/or environmental factors (most likely photoperiod and/or different threshold temperatures) are involved in controlling apical and lateral growth resumption after winter dormancy.

Branch xylem density variations across the Amazon Basin

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S. Patiño

2009-04-01

Full Text Available Xylem density is a physical property of wood that varies between individuals, species and environments. It reflects the physiological strategies of trees that lead to growth, survival and reproduction. Measurements of branch xylem density, ρ_x, were made for 1653 trees representing 598 species, sampled from 87 sites across the Amazon basin. Measured values ranged from 218 kg m⁻³ for a Cordia sagotii (Boraginaceae from Mountagne de Tortue, French Guiana to 1130 kg m⁻³ for an Aiouea sp. (Lauraceae from Caxiuana, Central Pará, Brazil. Analysis of variance showed significant differences in average ρ_x across regions and sampled plots as well as significant differences between families, genera and species. A partitioning of the total variance in the dataset showed that species identity (family, genera and species accounted for 33% with environment (geographic location and plot accounting for an additional 26%; the remaining "residual" variance accounted for 41% of the total variance. Variations in plot means, were, however, not only accountable by differences in species composition because xylem density of the most widely distributed species in our dataset varied systematically from plot to plot. Thus, as well as having a genetic component, branch xylem density is a plastic trait that, for any given species, varies according to where the tree is growing in a predictable manner. Within the analysed taxa, exceptions to this general rule seem to be pioneer species belonging for example to the Urticaceae whose branch xylem density is more constrained than most species sampled in this study. These patterns of variation of branch xylem density across Amazonia suggest a large functional diversity amongst Amazonian trees which is not well understood.

Xylem diameter changes during osmotic stress, desiccation and freezing in Pinus sylvestris and Populus tremula.

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Lintunen, Anna; Lindfors, Lauri; Nikinmaa, Eero; Hölttä, Teemu

2017-04-01

Trees experience low apoplastic water potential frequently in most environments. Low apoplastic water potential increases the risk of embolism formation in xylem conduits and creates dehydration stress for the living cells. We studied the magnitude and rate of xylem diameter change in response to decreasing apoplastic water potential and the role of living parenchyma cells in it to better understand xylem diameter changes in different environmental conditions. We compared responses of control and heat-injured xylem of Pinus sylvestris (L.) and Populus tremula (L.) branches to decreasing apoplastic water potential created by osmotic stress, desiccation and freezing. It was shown that xylem in control branches shrank more in response to decreasing apoplastic water potential in comparison with the samples that were preheated to damage living xylem parenchyma. By manipulating the osmotic pressure of the xylem sap, we observed xylem shrinkage due to decreasing apoplastic water potential even in the absence of water tension within the conduits. These results indicate that decreasing apoplastic water potential led to withdrawal of intracellular water from the xylem parenchyma, causing tissue shrinkage. The amount of xylem shrinkage per decrease in apoplastic water potential was higher during osmotic stress or desiccation compared with freezing. During desiccation, xylem diameter shrinkage involved both dehydration-related shrinkage of xylem parenchyma and water tension-induced shrinkage of conduits, whereas dehydration-related shrinkage of xylem parenchyma was accompanied by swelling of apoplastic ice during freezing. It was also shown that the exchange of water between symplast and apoplast within xylem is clearly faster than previously reported between the phloem and the xylem. Time constant of xylem shrinkage was 40 and 2 times higher during osmotic stress than during freezing stress in P. sylvestris and P. tremula, respectively. Finally, it was concluded that the

Transcriptome profiling in conifers and the PiceaGenExpress database show patterns of diversification within gene families and interspecific conservation in vascular gene expression

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Raherison Elie

2012-08-01

Full Text Available Abstract Background Conifers have very large genomes (13 to 30 Gigabases that are mostly uncharacterized although extensive cDNA resources have recently become available. This report presents a global overview of transcriptome variation in a conifer tree and documents conservation and diversity of gene expression patterns among major vegetative tissues. Results An oligonucleotide microarray was developed from Picea glauca and P. sitchensis cDNA datasets. It represents 23,853 unique genes and was shown to be suitable for transcriptome profiling in several species. A comparison of secondary xylem and phelloderm tissues showed that preferential expression in these vascular tissues was highly conserved among Picea spp. RNA-Sequencing strongly confirmed tissue preferential expression and provided a robust validation of the microarray design. A small database of transcription profiles called PiceaGenExpress was developed from over 150 hybridizations spanning eight major tissue types. In total, transcripts were detected for 92% of the genes on the microarray, in at least one tissue. Non-annotated genes were predominantly expressed at low levels in fewer tissues than genes of known or predicted function. Diversity of expression within gene families may be rapidly assessed from PiceaGenExpress. In conifer trees, dehydrins and late embryogenesis abundant (LEA osmotic regulation proteins occur in large gene families compared to angiosperms. Strong contrasts and low diversity was observed in the dehydrin family, while diverse patterns suggested a greater degree of diversification among LEAs. Conclusion Together, the oligonucleotide microarray and the PiceaGenExpress database represent the first resource of this kind for gymnosperm plants. The spruce transcriptome analysis reported here is expected to accelerate genetic studies in the large and important group comprised of conifer trees.

Response pattern of amino compounds in phloem and xylem of trees to soil drought depends on drought intensity and root symbiosis.

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Liu, X-P; Gong, C-M; Fan, Y-Y; Eiblmeier, M; Zhao, Z; Han, G; Rennenberg, H

2013-01-01

This study aimed to identify drought-mediated differences in amino nitrogen (N) composition and content of xylem and phloem in trees having different symbiotic N(2)-fixing bacteria. Under controlled water availability, 1-year-old seedlings of Robinia pseudoacacia (nodules with Rhizobium), Hippophae rhamnoides (symbiosis with Frankia) and Buddleja alternifolia (no such root symbiosis) were exposed to control, medium drought and severe drought, corresponding soil water content of 70-75%, 45-50% and 30-35% of field capacity, respectively. Composition and content of amino compounds in xylem sap and phloem exudates were analysed as a measure of N nutrition. Drought strongly reduced biomass accumulation in all species, but amino N content in xylem and phloem remained unaffected only in R. pseudoacacia. In H. rhamnoides and B. alternifolia, amino N in phloem remained constant, but increased in xylem of both species in response to drought. There were differences in composition of amino compounds in xylem and phloem of the three species in response to drought. Proline concentrations in long-distance transport pathways of all three species were very low, below the limit of detection in phloem of H. rhamnoides and in phloem and xylem of B. alternifolia. Apparently, drought-mediated changes in N composition were much more connected with species-specific changes in C:N ratios. Irrespective of soil water content, the two species with root symbioses did not show similar features for the different types of symbiosis, neither in N composition nor in N content. There was no immediate correlation between symbiotic N fixation and drought-mediated changes in amino N in the transport pathways. © 2012 German Botanical Society and The Royal Botanical Society of the Netherlands.

Differential expression of genes of Xylella fastidiosa in xylem fluid of citrus and grapevine.

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Shi, Xiangyang; Bi, Jianlong; Morse, Joseph G; Toscano, Nick C; Cooksey, Donald A

2010-03-01

Xylella fastidiosa causes a serious Pierce's disease (PD) in grapevine. Xylella fastidiosa cells from a PD strain were grown in a pure xylem fluid of a susceptible grapevine cultivar vs. xylem fluid from citrus, which is not a host for this strain of X. fastidiosa. When grown in grapevine xylem fluid, cells of the PD strain formed clumps and biofilm formed to a greater extent than in citrus xylem fluid, although the PD strain did grow in xylem fluid of three citrus varieties. The differential expression of selected genes of a PD X. fastidiosa strain cultured in the two xylem fluids was analyzed using a DNA macroarray. Compared with citrus xylem fluid, grapevine xylem fluid stimulated the expression of X. fastidiosa genes involved in virulence regulation, such as gacA, algU, xrvA, and hsq, and also genes involved in the biogenesis of pili and twitching motility, such as fimT, pilI, pilU, and pilY1. Increased gene expression likely contributes to PD expression in grapevine, whereas citrus xylem fluid did not support or possibly suppressed the expression of these virulence genes.

Xylem-to-phloem transfer of organic nitrogen in young soybean plants

International Nuclear Information System (INIS)

Da Silva, M.C.; Shelp, B.J.

1990-01-01

Xylem-to-phloem transfer in young vegetative soybean (Glycine max [L.] Merr.) plants (V4 stage) was identified as the difference in the distribution of [ 14 C]inulin, a xylem marker, and [ 14 C]aminoisobutyric acid (AIB), a synthetic amino acid, fed via the transpiration stream. Since [ 14 C]AIB was retained in the stem to some extent, whereas [ 14 C]inulin was not, the distribution of these marker compounds in each leaf was expressed as a percentage of the total [ 14 C] radioactivity recovered in the foliage. The developing third trifoliolate was a consistent and reliable indicator of xylem-to-phloem transfer. The phloem stream provided to the developing trifoliolate up to fourfold the relative proportion of solute received from the xylem stream; this was markedly reduced by increased light intensity and consequently water flow through the xylem. Evidence from heat girdling experiments is discussed with respect to the vascular anatomy of the soybean plant, and interpreted to suggest that direct xylem-to-phloem transfer in the stem, in the region of the second node, accounted for about one-half of the AIB supplied to the developing trifoliolate, with the remainder being provided from the second trifoliolate. Since AIB is not metabolized it seems likely that rapid transfer within the second trifoliolate occurred as direct veinal transfer rather than indirect cycling through the mesophyll. This study confirmed that xylem-to-phloem transfer plays a major role in the partitioning of nitrogen for early leaf development

Classifying Taiwan Lianas with Radiating Plates of Xylem

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Sheng-Zehn Yang

2015-12-01

Full Text Available Radiating plates of xylem are a lianas cambium variation, of which, 22 families have this feature. This study investigates 15 liana species representing nine families with radiating plates of xylem structures. The features of the transverse section and epidermis in fresh liana samples are documented, including shapes and colors of xylem and phloem, ray width and numbers, and skin morphology. Experimental results indicated that the shape of phloem fibers in Ampelopsis brevipedunculata var. hancei is gradually tapered and flame-like, which is in contrast with the other characteristics of this type, including those classified as rays. Both inner and outer cylinders of vascular bundles are found in Piper kwashoense, and the irregularly inner cylinder persists yet gradually diminishes. Red crystals are numerous in the cortex of Celastrus kusanoi. Aristolochia shimadai and A. zollingeriana develop a combination of two cambium variants, radiating plates of xylem and a lobed xylem. The shape of phloem in Stauntonia obovatifoliola is square or truncate, and its rays are numerous. Meanwhile, that of Neoalsomitra integrifolia is blunt and its rays are fewer. As for the features of a stem surface within the same family, Cyclea ochiaiana is brownish in color and has a deep vertical depression with lenticels, Pericampylus glaucus is greenish in color with a vertical shallow depression. Within the same genus, Aristolochia shimadai develops lenticels, which are not in A. zollingeriana; although the periderm developed in Clematis grata is a ring bark and tears easily, that of Clematis tamura is thick and soft.

Biosynthesis and metabolic fate of phenylalanine in conifers

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María Belén Pascual

2016-07-01

Full Text Available The amino acid phenylalanine (Phe is a critical metabolic node that plays an essential role in the interconnection between primary and secondary metabolism in plants. Phe is used as a protein building block but it is also as a precursor for numerous plant compounds that are crucial for plant reproduction, growth, development and defense against different types of stresses. The metabolism of Phe plays a central role in the channeling of carbon from photosynthesis to the biosynthesis of phenylpropanoids. The study of this metabolic pathway is particularly relevant in trees, which divert large amounts of carbon into the biosynthesis of Phe-derived compounds, particularly lignin, an important constituent of wood. The trunks of trees are metabolic sinks that consume a considerable percentage of carbon and energy from photosynthesis, and carbon is finally immobilized in wood. This paper reviews recent advances in the biosynthesis and metabolic utilization of Phe in conifer trees. Two alternative routes have been identified: the ancient phenylpyruvate pathway that is present in microorganisms, and the arogenate pathway that possibly evolved later during plant evolution. Additionally, an efficient nitrogen recycling mechanism is required to maintain sustained growth during xylem formation. The relevance of phenylalanine metabolic pathways in wood formation, the biotic interactions and ultraviolet protection is discussed. The genetic manipulation and transcriptional regulation of the pathways are also outlined.

Biosynthesis and Metabolic Fate of Phenylalanine in Conifers.

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Pascual, María B; El-Azaz, Jorge; de la Torre, Fernando N; Cañas, Rafael A; Avila, Concepción; Cánovas, Francisco M

2016-01-01

The amino acid phenylalanine (Phe) is a critical metabolic node that plays an essential role in the interconnection between primary and secondary metabolism in plants. Phe is used as a protein building block but it is also as a precursor for numerous plant compounds that are crucial for plant reproduction, growth, development, and defense against different types of stresses. The metabolism of Phe plays a central role in the channeling of carbon from photosynthesis to the biosynthesis of phenylpropanoids. The study of this metabolic pathway is particularly relevant in trees, which divert large amounts of carbon into the biosynthesis of Phe-derived compounds, particularly lignin, an important constituent of wood. The trunks of trees are metabolic sinks that consume a considerable percentage of carbon and energy from photosynthesis, and carbon is finally immobilized in wood. This paper reviews recent advances in the biosynthesis and metabolic utilization of Phe in conifer trees. Two alternative routes have been identified: the ancient phenylpyruvate pathway that is present in microorganisms, and the arogenate pathway that possibly evolved later during plant evolution. Additionally, an efficient nitrogen recycling mechanism is required to maintain sustained growth during xylem formation. The relevance of phenylalanine metabolic pathways in wood formation, the biotic interactions, and ultraviolet protection is discussed. The genetic manipulation and transcriptional regulation of the pathways are also outlined.

Xylem development in prunus flower buds and the relationship to deep supercooling.

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Ashworth, E N

1984-04-01

Xylem development in eight Prunus species was examined and the relationship to deep supercooling assessed. Dormant buds of six species, P. armeniaca, P. avium, P. cerasus, P. persica, P. salicina, and P. sargentii deep supercooled. Xylem vessel elements were not observed within the dormant floral primordia of these species. Instead, discrete bundles containing procambial cells were observed. Vascular differentiation resumed and xylem continuity was established during the time that the capacity to deep supercool was lost. In P. serotina and P. virginiana, two species which do not supercool, xylem vessels ran the length of the inflorescence and presumably provided a conduit for the spread of ice into the bud. The results support the hypothesis that the lack of xylem continuity is an important feature of buds which deep supercool.

How does climate influence xylem morphogenesis over the growing season? Insights from long-term intra-ring anatomy in Picea abies.

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Castagneri, Daniele; Fonti, Patrick; von Arx, Georg; Carrer, Marco

2017-04-01

During the growing season, the cambium of conifer trees produces successive rows of xylem cells, the tracheids, that sequentially pass through the phases of enlargement and secondary wall thickening before dying and becoming functional. Climate variability can strongly influence the kinetics of morphogenetic processes, eventually affecting tracheid shape and size. This study investigates xylem anatomical structure in the stem of Picea abies to retrospectively infer how, in the long term, climate affects the processes of cell enlargement and wall thickening. Tracheid anatomical traits related to the phases of enlargement (diameter) and wall thickening (wall thickness) were innovatively inspected at the intra-ring level on 87-year-long tree-ring series in Picea abies trees along a 900 m elevation gradient in the Italian Alps. Anatomical traits in ten successive tree-ring sectors were related to daily temperature and precipitation data using running correlations. Close to the altitudinal tree limit, low early-summer temperature negatively affected cell enlargement. At lower elevation, water availability in early summer was positively related to cell diameter. The timing of these relationships shifted forward by about 20 (high elevation) to 40 (low elevation) d from the first to the last tracheids in the ring. Cell wall thickening was affected by climate in a different period in the season. In particular, wall thickness of late-formed tracheids was strongly positively related to August-September temperature at high elevation. Morphogenesis of tracheids sequentially formed in the growing season is influenced by climate conditions in successive periods. The distinct climate impacts on cell enlargement and wall thickening indicate that different morphogenetic mechanisms are responsible for different tracheid traits. Our approach of long-term and high-resolution analysis of xylem anatomy can support and extend short-term xylogenesis observations, and increase our

Insights into Conifer Giga-Genomes1

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De La Torre, Amanda R.; Birol, Inanc; Bousquet, Jean; Ingvarsson, Pär K.; Jansson, Stefan; Jones, Steven J.M.; Keeling, Christopher I.; MacKay, John; Nilsson, Ove; Ritland, Kermit; Street, Nathaniel; Yanchuk, Alvin; Zerbe, Philipp; Bohlmann, Jörg

2014-01-01

Insights from sequenced genomes of major land plant lineages have advanced research in almost every aspect of plant biology. Until recently, however, assembled genome sequences of gymnosperms have been missing from this picture. Conifers of the pine family (Pinaceae) are a group of gymnosperms that dominate large parts of the world’s forests. Despite their ecological and economic importance, conifers seemed long out of reach for complete genome sequencing, due in part to their enormous genome size (20–30 Gb) and the highly repetitive nature of their genomes. Technological advances in genome sequencing and assembly enabled the recent publication of three conifer genomes: white spruce (Picea glauca), Norway spruce (Picea abies), and loblolly pine (Pinus taeda). These genome sequences revealed distinctive features compared with other plant genomes and may represent a window into the past of seed plant genomes. This Update highlights recent advances, remaining challenges, and opportunities in light of the publication of the first conifer and gymnosperm genomes. PMID:25349325

Influence of xylem ray integrity and degree of polymerization on bending strength of beech wood decayed by Pleurotus ostreatus and Trametes versicolor

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Ehsan Bari; Reza Oladi; Olaf Schmidt; Carol A. Clausen; Katie Ohno; Darrel D. Nicholas; Mehrdad Ghodskhah Daryaei; Maryam Karim

2015-01-01

The scope of this research was to evaluate the influence of xylem ray (XR) and degree of polymerization (DP) of holocellulose in Oriental beech wood (Fagus orientalis Lipsky.) on impact bending strength against two white-rot fungi. Beech wood specimens, exposed to Pleurotus ostreatus and Trametes versicolor, were evaluated for...

Analysis of xylem formation in pine by cDNA sequencing

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Allona, I.; Quinn, M.; Shoop, E.; Swope, K.; St Cyr, S.; Carlis, J.; Riedl, J.; Retzel, E.; Campbell, M. M.; Sederoff, R.;

Protein and metabolite composition of xylem sap from field-grown soybeans (Glycine max).

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Krishnan, Hari B; Natarajan, Savithiry S; Bennett, John O; Sicher, Richard C

2011-05-01

The xylem, in addition to transporting water, nutrients and metabolites, is also involved in long-distance signaling in response to pathogens, symbionts and environmental stresses. Xylem sap has been shown to contain a number of proteins including metabolic enzymes, stress-related proteins, signal transduction proteins and putative transcription factors. Previous studies on xylem sap have mostly utilized plants grown in controlled environmental chambers. However, plants in the field are subjected to high light and to environmental stress that is not normally found in growth chambers. In this study, we have examined the protein and metabolite composition of xylem sap from field-grown cultivated soybean plants. One-dimensional gel electrophoresis of xylem sap from determinate, indeterminate, nodulating and non-nodulating soybean cultivars revealed similar protein profiles consisting of about 8-10 prominent polypeptides. Two-dimensional gel electrophoresis of soybean xylem sap resulted in the visualization of about 60 distinct protein spots. A total of 38 protein spots were identified using MALDI-TOF MS and LC-MS/MS. The most abundant proteins present in the xylem sap were identified as 31 and 28 kDa vegetative storage proteins. In addition, several proteins that are conserved among different plant species were also identified. Diurnal changes in the metabolite profile of xylem sap collected during a 24-h cycle revealed that asparagine and aspartate were the two predominant amino acids irrespective of the time collected. Pinitol (D-3-O-methyl-chiro-inositol) was the most abundant carbohydrate present. The possible roles of xylem sap proteins and metabolites as nutrient reserves for sink tissue and as an indicator of biotic stress are also discussed.

Overexpression and cosuppression of xylem-related genes in an early xylem differentiation stage-specific manner by the AtTED4 promoter.

Science.gov (United States)

Endo, Satoshi; Iwamoto, Kuninori; Fukuda, Hiroo

2018-02-01

Tissue-specific overexpression of useful genes, which we can design according to their cause-and-effect relationships, often gives valuable gain-of-function phenotypes. To develop genetic tools in woody biomass engineering, we produced a collection of Arabidopsis lines that possess chimeric genes of a promoter of an early xylem differentiation stage-specific gene, Arabidopsis Tracheary Element Differentiation-related 4 (AtTED4) and late xylem development-associated genes, many of which are uncharacterized. The AtTED4 promoter directed the expected expression of transgenes in developing vascular tissues from young to mature stage. Of T2 lines examined, 42%, 49% and 9% were judged as lines with the nonrepeat type insertion, the simple repeat type insertion and the other repeat type insertion of transgenes. In 174 T3 lines, overexpression lines were confirmed for 37 genes, whereas only cosuppression lines were produced for eight genes. The AtTED4 promoter activity was high enough to overexpress a wide range of genes over wild-type expression levels, even though the wild-type expression is much higher than AtTED4 expression for several genes. As a typical example, we investigated phenotypes of pAtTED4::At5g60490 plants, in which both overexpression and cosuppression lines were included. Overexpression but not cosuppression lines showed accelerated xylem development, suggesting the positive role of At5g60490 in xylem development. Taken together, this study provides valuable results about behaviours of various genes expressed under an early xylem-specific promoter and about usefulness of their lines as genetic tools in woody biomass engineering. © 2017 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.

Xylem hydraulic properties of roots and stems of nine Mediterranean woody species.

Science.gov (United States)

Martínez-Vilalta, Jordi; Prat, Ester; Oliveras, Imma; Piñol, Josep

2002-09-01

We studied the hydraulic architecture and water relations of nine co-occurring woody species in a Spanish evergreen oak forest over the course of a dry season. Our main objectives were to: (1) test the existence of a trade-off between hydraulic conductivity and security in the xylem, and (2) establish the safety margins at which the species operated in relation to hydraulic failure, and compare these safety margins between species and tissues (roots vs. stems). Our results showed that the relationship between specific hydraulic conductivity (K s) and resistance to cavitation followed a power function with exponent ≈-2, consistent with the existence of a trade-off between conductivity and security in the xylem, and also consistent with a linear relationship between vessel diameter and the size of inter-vessel pores. The diameter of xylem conduits, K s and vulnerability to xylem embolism were always higher in roots than in stems of the same species. Safety margins from hydraulic failure were narrower in roots than in stems. Among species, the water potential (Ψ) at which 50% of conductivity was lost due to embolism ranged between -0.9 and Cistus albidus=Ilex aquifolium>Phillyrea latifolia>Juniperus oxycedrus. Gas exchange and seasonal Ψ minima were in general correlated with resistance to xylem embolism. Hydraulic safety margins differed markedly among species, with some of them (J. oxycedrus, I. aquifolium, P. latifolia) showing a xylem overly resistant to cavitation. We hypothesize that this overly resistant xylem may be related to the shape of the relationship between K s and security we have found.

Compositions and methods for xylem-specific expression in plant cells

Energy Technology Data Exchange (ETDEWEB)

Han, Kyung-Hwan; Ko, Jae-Heung

2017-12-19

The invention provides promoter sequences that regulate specific expression of operably linked sequences in developing xylem cells and/or in developing xylem tissue. The developing xylem-specific sequences are exemplified by the DX5, DX8, DX11, and DX15 promoters, portions thereof, and homologs thereof. The invention further provides expression vectors, cells, tissues and plants that contain the invention's sequences. The compositions of the invention and methods of using them are useful in, for example, improving the quantity (biomass) and/or the quality (wood density, lignin content, sugar content etc.) of expressed biomass feedstock products that may be used for bioenergy, biorefinary, and generating wood products such as pulp, paper, and solid wood.

Functional water flow pathways and hydraulic regulation in the xylem network of Arabidopsis.

Science.gov (United States)

Park, Joonghyuk; Kim, Hae Koo; Ryu, Jeongeun; Ahn, Sungsook; Lee, Sang Joon; Hwang, Ildoo

2015-03-01

In vascular plants, the xylem network constitutes a complex microfluidic system. The relationship between vascular network architecture and functional hydraulic regulation during actual water flow remains unexplored. Here, we developed a method to visualize individual xylem vessels of the 3D xylem network of Arabidopsis thaliana, and to analyze the functional activities of these vessels using synchrotron X-ray computed tomography with hydrophilic gold nanoparticles as flow tracers. We show how the organization of the xylem network changes dynamically throughout the plant, and reveal how the elementary units of this transport system are organized to ensure both long-distance axial water transport and local lateral water transport. Xylem vessels form distinct clusters that operate as functional units, and the activity of these units, which determines water flow pathways, is modulated not only by varying the number and size of xylem vessels, but also by altering their interconnectivity and spatial arrangement. Based on these findings, we propose a regulatory model of water transport that ensures hydraulic efficiency and safety. © The Author 2014. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Sugar export limits size of conifer needles

DEFF Research Database (Denmark)

Rademaker, Hanna; Zwieniecki, Maciej A.; Bohr, Tomas

2017-01-01

Plant leaf size varies by more than three orders of magnitude, from a few millimeters to over one meter. Conifer leaves, however, are relatively short and the majority of needles are no longer than 6 cm. The reason for the strong confinement of the trait-space is unknown. We show that sugars...... does not contribute to sugar flow. Remarkably, we find that the size of the active part does not scale with needle length. We predict a single maximum needle size of 5 cm, in accord with data from 519 conifer species. This could help rationalize the recent observation that conifers have significantly...

Tolerance to oxidative stress is required for maximal xylem colonization by the xylem-limited bacterial phytopathogen, Xylella fastidiosa.

Science.gov (United States)

Wang, Peng; Lee, Yunho; Igo, Michele M; Roper, M Caroline

2017-09-01

Bacterial plant pathogens often encounter reactive oxygen species (ROS) during host invasion. In foliar bacterial pathogens, multiple regulatory proteins are involved in the sensing of oxidative stress and the activation of the expression of antioxidant genes. However, it is unclear whether xylem-limited bacteria, such as Xylella fastidiosa, experience oxidative stress during the colonization of plants. Examination of the X. fastidiosa genome uncovered only one homologue of oxidative stress regulatory proteins, OxyR. Here, a knockout mutation in the X. fastidiosa oxyR gene was constructed; the resulting strain was significantly more sensitive to hydrogen peroxide (H 2 O 2 ) relative to the wild-type. In addition, during early stages of grapevine infection, the survival rate was 1000-fold lower for the oxyR mutant than for the wild-type. This supports the hypothesis that grapevine xylem represents an oxidative environment and that X. fastidiosa must overcome this challenge to achieve maximal xylem colonization. Finally, the oxyR mutant exhibited reduced surface attachment and cell-cell aggregation and was defective in biofilm maturation, suggesting that ROS could be a potential environmental cue stimulating biofilm development during the early stages of host colonization. © 2016 BSPP AND JOHN WILEY & SONS LTD.

Sugars from woody tissue photosynthesis reduce xylem vulnerability to cavitation.

Science.gov (United States)

De Baerdemaeker, Niels J F; Salomón, Roberto Luis; De Roo, Linus; Steppe, Kathy

2017-11-01

Reassimilation of internal CO 2 via woody tissue photosynthesis has a substantial effect on tree carbon income and wood production. However, little is known about its role in xylem vulnerability to cavitation and its implications in drought-driven tree mortality. Young trees of Populus nigra were subjected to light exclusion at the branch and stem levels. After 40 d, measurements of xylem water potential, diameter variation and acoustic emission (AE) were performed in detached branches to obtain acoustic vulnerability curves to cavitation following bench-top dehydration. Acoustic vulnerability curves and derived AE 50 values (i.e. water potential at which 50% of cavitation-related acoustic emissions occur) differed significantly between light-excluded and control branches (AE 50,light-excluded  = -1.00 ± 0.13 MPa; AE 50,control  = -1.45 ± 0.09 MPa; P = 0.007) denoting higher vulnerability to cavitation in light-excluded trees. Woody tissue photosynthesis represents an alternative and immediate source of nonstructural carbohydrates (NSC) that confers lower xylem vulnerability to cavitation via sugar-mediated mechanisms. Embolism repair and xylem structural changes could not explain this observation as the amount of cumulative AE and basic wood density did not differ between treatments. We suggest that woody tissue assimilates might play a role in the synthesis of xylem surfactants for nanobubble stabilization under tension. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

Direct observation of local xylem embolisms induced by soil drying in intact Zea mays leaves.

Science.gov (United States)

Ryu, Jeongeun; Hwang, Bae Geun; Kim, Yangmin X; Lee, Sang Joon

2016-04-01

The vulnerability of vascular plants to xylem embolism is closely related to their stable long-distance water transport, growth, and survival. Direct measurements of xylem embolism are required to understand what causes embolism and what strategies plants employ against it. In this study, synchrotron X-ray microscopy was used to non-destructively investigate both the anatomical structures of xylem vessels and embolism occurrence in the leaves of intact Zea mays (maize) plants. Xylem embolism was induced by water stress at various soil drying periods and soil water contents. X-ray images of dehydrated maize leaves showed that the ratio of gas-filled vessels to all xylem vessels increased with decreased soil water content and reached approximately 30% under severe water stress. Embolism occurred in some but not all vessels. Embolism in maize leaves was not strongly correlated with xylem diameter but was more likely to occur in the peripheral veins. The rate of embolism formation in metaxylem vessels was higher than in protoxylem vessels. This work has demonstrated that xylem embolism remains low in maize leaves under water stress and that there xylem has characteristic spatial traits of vulnerability to embolism. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Soft valves in plants

Science.gov (United States)

Park, Keunhwan; Tixier, Aude; Christensen, Anneline; Arnbjerg-Nielsen, Sif; Zwieniecki, Maciej; Jensen, Kaare

2017-11-01

Water and minerals flow from plant roots to leaves in the xylem, an interconnected network of vascular conduits that spans the full length of the organism. When a plant is subjected to drought stress, air pockets can spread inside the xylem, threatening the survival of the plant. Many plants prevent propagation of air by using hydrophobic nano-membranes in the ``pit'' pores that link adjacent xylem cells. This adds considerable resistance to flow. Interestingly, torus-margo pit pores in conifers are open and offer less resistance. To prevent propagation of air, conifers use a soft gating mechanism, which relies on hydrodynamic interactions between the xylem liquid and the elastic pit. However, it is unknown exactly how it is able to combine the seemingly antagonist functions of high permeability and resistance to propagation of air. We conduct experiments on biomimetic pores to elucidate the flow regulation mechanism. The design of plant valves is compared to other natural systems and optimal strategies are discussed. This work was supported by a research Grant (13166) from VILLUM FONDEN.

Conservation of element concentration in xylem sap of red spruce

Science.gov (United States)

Kevin T. Smith; Walter C. Shortle

2001-01-01

We investigated the chemistry of xylem sap as a marker of red spruce metabolism and soil chemistry at three locations in northern New England. A Scholander pressure chamber was used to extract xylem sap from roots and branches cut from mature trees in early June and September. Root sap contained significantly greater concentrations of K, Ca, Mg, Mn, and A1 than branch...

Comparative interrogation of the developing xylem transcriptomes of two wood-forming species: Populus trichocarpa and Eucalyptus grandis.

Science.gov (United States)

Hefer, Charles A; Mizrachi, Eshchar; Myburg, Alexander A; Douglas, Carl J; Mansfield, Shawn D

2015-06-01

Wood formation is a complex developmental process governed by genetic and environmental stimuli. Populus and Eucalyptus are fast-growing, high-yielding tree genera that represent ecologically and economically important species suitable for generating significant lignocellulosic biomass. Comparative analysis of the developing xylem and leaf transcriptomes of Populus trichocarpa and Eucalyptus grandis together with phylogenetic analyses identified clusters of homologous genes preferentially expressed during xylem formation in both species. A conserved set of 336 single gene pairs showed highly similar xylem preferential expression patterns, as well as evidence of high functional constraint. Individual members of multi-gene orthologous clusters known to be involved in secondary cell wall biosynthesis also showed conserved xylem expression profiles. However, species-specific expression as well as opposite (xylem versus leaf) expression patterns observed for a subset of genes suggest subtle differences in the transcriptional regulation important for xylem development in each species. Using sequence similarity and gene expression status, we identified functional homologs likely to be involved in xylem developmental and biosynthetic processes in Populus and Eucalyptus. Our study suggests that, while genes involved in secondary cell wall biosynthesis show high levels of gene expression conservation, differential regulation of some xylem development genes may give rise to unique xylem properties. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

The photochemical reflectance index provides an optical indicator of spring photosynthetic activation in evergreen conifers.

Science.gov (United States)

Wong, Christopher Y S; Gamon, John A

2015-04-01

In evergreens, the seasonal down-regulation and reactivation of photosynthesis is largely invisible and difficult to assess with remote sensing. This invisible phenology may be changing as a result of climate change. To better understand the mechanism and timing of these hidden physiological transitions, we explored several assays and optical indicators of spring photosynthetic activation in conifers exposed to a boreal climate. The photochemical reflectance index (PRI), chlorophyll fluorescence, and leaf pigments for evergreen conifer seedlings were monitored over 1 yr of a boreal climate with the addition of gas exchange during the spring. PRI, electron transport rate, pigment levels, light-use efficiency and photosynthesis all exhibited striking seasonal changes, with varying kinetics and strengths of correlation, which were used to evaluate the mechanisms and timing of spring activation. PRI and pigment pools were closely timed with photosynthetic reactivation measured by gas exchange. The PRI provided a clear optical indicator of spring photosynthetic activation that was detectable at leaf and stand scales in conifers. We propose that PRI might provide a useful metric of effective growing season length amenable to remote sensing and could improve remote-sensing-driven models of carbon uptake in evergreen ecosystems. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

Annosus Root disease of Western Conifers (FIDL)

Science.gov (United States)

Craig L. Schmitt; John R. Parmeter; John T. Kliejunas

2000-01-01

Annosus root disease is found on all western conifer species but is of most concern on true firs, hemlocks, and pines. Incense cedar, coast redwood and sequoia are sometimes infected in California. Western juniper is infected throughout its range. Annosus is common and causes extensive decay in old-growth western and mountain hemlock stands. Many mixed conifer stands...

Conifer-Derived Monoterpenes and Forest Walking

OpenAIRE

Sumitomo, Kazuhiro; Akutsu, Hiroaki; Fukuyama, Syusei; Minoshima, Akiho; Kukita, Shin; Yamamura, Yuji; Sato, Yoshiaki; Hayasaka, Taiki; Osanai, Shinobu; Funakoshi, Hiroshi; Hasebe, Naoyuki; Nakamura, Masao

2015-01-01

Conifer and broadleaf trees emit volatile organic compounds in the summer. The major components of these emissions are volatile monoterpenes. Using solid phase microextraction fiber as the adsorbant, monoterpenes were successfully detected and identified in forest air samples. Gas chromatography/mass chromatogram of monoterpenes in the atmosphere of a conifer forest and that of serum from subjects who were walking in a forest were found to be similar each other. The amounts of α-pinene in the...

Conifers in cold environments synchronize maximum growth rate of tree-ring formation with day length.

Science.gov (United States)

Rossi, Sergio; Deslauriers, Annie; Anfodillo, Tommaso; Morin, Hubert; Saracino, Antonio; Motta, Renzo; Borghetti, Marco

2006-01-01

Intra-annual radial growth rates and durations in trees are reported to differ greatly in relation to species, site and environmental conditions. However, very similar dynamics of cambial activity and wood formation are observed in temperate and boreal zones. Here, we compared weekly xylem cell production and variation in stem circumference in the main northern hemisphere conifer species (genera Picea, Pinus, Abies and Larix) from 1996 to 2003. Dynamics of radial growth were modeled with a Gompertz function, defining the upper asymptote (A), x-axis placement (beta) and rate of change (kappa). A strong linear relationship was found between the constants beta and kappa for both types of analysis. The slope of the linear regression, which corresponds to the time at which maximum growth rate occurred, appeared to converge towards the summer solstice. The maximum growth rate occurred around the time of maximum day length, and not during the warmest period of the year as previously suggested. The achievements of photoperiod could act as a growth constraint or a limit after which the rate of tree-ring formation tends to decrease, thus allowing plants to safely complete secondary cell wall lignification before winter.

Organic geochemical studies of the transformation of gymnospermous xylem during peatification and coalification to subbituminous coal

Science.gov (United States)

Hatcher, P.G.; Lerch, H. E.; Verheyen, T.V.

1990-01-01

It is generally recognized that xylem from trees that are buried in peat swamps is transformed first to huminite macerals in brown coal and then to vitrinite macerals in bituminous coal by processes collectively known as coalification. In order to understand the chemical nature of coalification of xylem and the chemical structures that eventually evolve in coal, we examined a series of gymnospermous xylem samples coalified to varying degrees. The samples included modern fresh xylem, modern degraded xylem in peat, and xylem coalified to ranks of brown coal (lignite B), lignite A, and subbituminous coal. The organic geochemical methods used in this study included solid-state 13C nuclear magnetic resonance (NMR) and pyrolysis/gas chromatography/mass spectrometry. The NMR method provided average compositional information, and the pyrolysis provided detailed molecular information. Although the samples examined include different plants of different geologic ages, they all share a common feature in that they are gymnospermous and presumably have or had a similar kind of lignin. The data obtained in this study provide enough details to allow delineation of specific coalification pathway for the xylem is microbial degradation in peat (peatification), leading to selective removal of cellulosic components. These components constitute a large fraction of the total mass of xylem, usually greater than 50%. Although cellulosic components can survive degradation under certain conditions, their loss during microbial degradation is the rule rather than exception during peatification. As these components of xylem are degraded and lost, lignin, another major component of xylem, is selectively enriched because it is more resistant to microbial degradation than the cellulosic components. Thus, lignin survives peatification in a practically unaltered state and becomes the major precursor of coalified xylem. During its transformation to brown coal and lignite A, lignin in xylem is altered

Wound-induced and bacteria-induced xylem blockage in roses, Astilbe and Viburnum

NARCIS (Netherlands)

Loubaud, M.; Doorn, van W.G.

2004-01-01

We previously concluded that the xylem blockage that prevents water uptake into several cut flowers is mainly due to the presence of bacteria, whilst in chrysanthemum and Bouvardia we observed a xylem occlusion that was mainly due to a wound-reaction of the plant. We have further tested which of

Effect of gamma-irradiation and colchicine on cell division and differentiation of xylem elements in citrus limon juice vesicle cultures

International Nuclear Information System (INIS)

Khan, Aysha; Chauhan, Y.S.

1999-01-01

The effects of varying doses of gamma irradiation on cell division and cytodifferentiation of tracheary elements in cultured juice vesicles of Citrus limon (L) Burmann var. Assam lemon were investigated. Low radiation doses stimulated cell division and differentiation of xylem fibres, sclereids and tracheids in explants given up to 10 Gy of gamma rays. Although cell division and cytodifferentiation of fibers and sclereids occurred in explants exposed to 150 dose of Gy radiation, the intensity of differentiation was much less than that induced by 10 Gy radiation dose. Amongst the differential elements, tracheids were more sensitive to radiation than fibres and sclereids. The requirement of cell division for differentiation of xylem cells was also studied by using different concentrations of colchicine in Citrus limon juice vesicle cultures. It was found that the low concentrations of colchicine permitted normal cell division and also resulted in normal differentiation of xylem cells; higher colchicine concentration, however, inhibited cell division as well as differentiation and resulted in an abnormal differentiation of tracheary element. A positive correlation between intensity of nucleic acid staining and cell division in both the above-mentioned experiments was qualitatively confirmed by Azur B staining test of nucleic acid. Thus, it was concluded that juice vesicle parenchyma cells go through nucleic acid synthesis, followed by cell division before differentiation. (author)

Natural product terpenoids in Eocene and Miocene conifer fossils.

Science.gov (United States)

Otto, Angelika; White, James D; Simoneit, Bernd R T

2002-08-30

Numerous saturated and aromatic hydrocarbons, but not polar compounds, originating from plants and microorganisms (biomarkers) have been reported in sediments, coals, and petroleum. Here we describe natural product terpenoids found in two fossil conifers, Taxodium balticum (Eocene) and Glyptostrobus oregonensis (Miocene). A similar terpenoid pattern is also observed in extant Taxodium distichum. The preservation of characteristic terpenoids (unaltered natural products) in the fossil conifers supports their systematic assignment to the Cypress family (Cupressaceae sensu lato). The results also show that fossil conifers can contain polar terpenoids, which are valuable markers for (paleo)chemosystematics and phylogeny.

Some considerations on the effect of xylem embolism in conductivity Hydraulic plant

International Nuclear Information System (INIS)

Socorro, Alfredo

2008-01-01

From the physical characteristics of the elements that make up the xylem tissue in the stems of plants, a hypotheses is proposed to obtain a mathematical expression that defines Water flows through these conductors systems, depending on the potential difference water between the top and bottom of the stem. It raises an expression for the number of air bubbles formed from the imperfections (pores) in the walls of the tracheids forming xylem vessels and high stresses to which it is subjected in this transpiration high activity situations. This leads to an equation for conductivity hydraulic function of water potential in the presence of xylem embolism. using data from the literature and estimated values ​​simulated values ​​is performed stream and the percentage loss of conductivity. These results are compared with evidence and practice is discussed on the basis of physiological mechanisms relating to vulnerability of plants to xylem cavitation. It analyzes how this situation can be be corrected, also valued as this phenomenon affects situations of water stress

Measurement of xylem translocation of weak electrolytes with the pressure chamber technique

DEFF Research Database (Denmark)

Ciucani, Giovannella; Trevisan, M.; Sacchi, G.A.

2002-01-01

and triasulfuron). The compounds covered a wide range of log K-OW and pK(a) values. Concentrations in external solution and in xylem sap were measured by HPLC at pH values in external solution of 4.5, 6.5 and 8.5. For weak bases, translocation was higher at low pH and the transpiration stream concentration factors...... (TSCF) were in the range 0.31-0.95. At pH 8.5, the concentrations in leaking xylem sap were very low for fenpropimorph, and steady-state was probably not reached. For weak acids, TSCF values derived with external pH from 4.5 to 8.5 were in the range 0.55-1.50 for primisulfuron-methyl, 0...... to regulate their xylem sap pH, which was almost identical to the pH in external solution. Without pH differences, the ion-trap process, which is responsible for accumulation or exclusion of weak acids and bases in the xylem of living plants, does not take place. Model simulations carried out for intact...

Management strategies for bark beetles in conifer forests

Science.gov (United States)

Christopher Fettig; Jacek  Hilszczański

2015-01-01

Several species of bark beetles (Coleoptera: Curculionidae, Scolytinae) are capable of causing significant amounts of tree mortality in conifer forests throughout much of the world.  In most cases, these events are part of the ecology of conifer forests and positively influence many ecological processes, but the economic and social implications can be...

ConiferEST: an integrated bioinformatics system for data reprocessing and mining of conifer expressed sequence tags (ESTs).

Science.gov (United States)

Liang, Chun; Wang, Gang; Liu, Lin; Ji, Guoli; Fang, Lin; Liu, Yuansheng; Carter, Kikia; Webb, Jason S; Dean, Jeffrey F D

2007-05-29

With the advent of low-cost, high-throughput sequencing, the amount of public domain Expressed Sequence Tag (EST) sequence data available for both model and non-model organism is growing exponentially. While these data are widely used for characterizing various genomes, they also present a serious challenge for data quality control and validation due to their inherent deficiencies, particularly for species without genome sequences. ConiferEST is an integrated system for data reprocessing, visualization and mining of conifer ESTs. In its current release, Build 1.0, it houses 172,229 loblolly pine EST sequence reads, which were obtained from reprocessing raw DNA sequencer traces using our software--WebTraceMiner. The trace files were downloaded from NCBI Trace Archive. ConiferEST provides biologists unique, easy-to-use data visualization and mining tools for a variety of putative sequence features including cloning vector segments, adapter sequences, restriction endonuclease recognition sites, polyA and polyT runs, and their corresponding Phred quality values. Based on these putative features, verified sequence features such as 3' and/or 5' termini of cDNA inserts in either sense or non-sense strand have been identified in-silico. Interestingly, only 30.03% of the designated 3' ESTs were found to have an authenticated 5' terminus in the non-sense strand (i.e., polyT tails), while fewer than 5.34% of the designated 5' ESTs had a verified 5' terminus in the sense strand. Such previously ignored features provide valuable insight for data quality control and validation of error-prone ESTs, as well as the ability to identify novel functional motifs embedded in large EST datasets. We found that "double-termini adapters" were effective indicators of potential EST chimeras. For all sequences with in-silico verified termini/terminus, we used InterProScan to assign protein domain signatures, results of which are available for in-depth exploration using our biologist

ConiferEST: an integrated bioinformatics system for data reprocessing and mining of conifer expressed sequence tags (ESTs

Directory of Open Access Journals (Sweden)

Carter Kikia

2007-05-01

Full Text Available Abstract Background With the advent of low-cost, high-throughput sequencing, the amount of public domain Expressed Sequence Tag (EST sequence data available for both model and non-model organism is growing exponentially. While these data are widely used for characterizing various genomes, they also present a serious challenge for data quality control and validation due to their inherent deficiencies, particularly for species without genome sequences. Description ConiferEST is an integrated system for data reprocessing, visualization and mining of conifer ESTs. In its current release, Build 1.0, it houses 172,229 loblolly pine EST sequence reads, which were obtained from reprocessing raw DNA sequencer traces using our software – WebTraceMiner. The trace files were downloaded from NCBI Trace Archive. ConiferEST provides biologists unique, easy-to-use data visualization and mining tools for a variety of putative sequence features including cloning vector segments, adapter sequences, restriction endonuclease recognition sites, polyA and polyT runs, and their corresponding Phred quality values. Based on these putative features, verified sequence features such as 3' and/or 5' termini of cDNA inserts in either sense or non-sense strand have been identified in-silico. Interestingly, only 30.03% of the designated 3' ESTs were found to have an authenticated 5' terminus in the non-sense strand (i.e., polyT tails, while fewer than 5.34% of the designated 5' ESTs had a verified 5' terminus in the sense strand. Such previously ignored features provide valuable insight for data quality control and validation of error-prone ESTs, as well as the ability to identify novel functional motifs embedded in large EST datasets. We found that "double-termini adapters" were effective indicators of potential EST chimeras. For all sequences with in-silico verified termini/terminus, we used InterProScan to assign protein domain signatures, results of which are available

Alien conifer invasions in South America: short fuse burning?

CSIR Research Space (South Africa)

Richardson, DM

2007-01-01

Full Text Available conifers has a much shorter history in South America, and invasions are a recent phenomenon. A workshop was convened in Argentina in May 2007 to discuss the rapid emergence of problems with invasive conifers in South America. Workshop delegates agreed that...

Mediterranean climate effects. II. Conifer growth phenology across a Sierra Nevada ecotone.

Science.gov (United States)

Royce, E B; Barbour, M G

2001-05-01

Growth and xylem water potential of the lower elevation conifers Pinus jeffreyi and Abies concolor and the higher elevation Pinus monticola and Abies magnifica were monitored in their montane Mediterranean habitat of the southernmost Sierra Nevada mountains of California. Measurements were made across the ecotone between the midmontane and upper montane forests and through light and heavy snowfall years.Radial stem growth, averaging ∼1.5 mm/yr, started 2 wk after snow melt, providing that maximum air temperatures had reached 21°C, and ended when predawn water potentials fell rapidly at the onset of the summer drought. Leader growth started on or after a fixed date, providing that minimum air temperatures were above -4°C for Pinus species or +2.5°C for Abies species. The cue for leader growth was inferred to be photoperiodic. Leader growth ended when either a determinate internode length of ∼1 mm was reached or predawn water potentials fell rapidly. Abies magnifica grew more rapidly than the low-elevation species, but had a shorter growth period; its annual leader growth, as a consequence, was only 35 mm/yr vs. 50 mm/yr for the low-elevation species. Needle growth was similarly determinate in the absence of early drought. This growth phenology contributes to determining species distribution across the ecotone.

The effector repertoire of Fusarium oxysporum determines the tomato xylem proteome composition following infection

Directory of Open Access Journals (Sweden)

Fleur eGawehns

2015-11-01

Full Text Available Plant pathogens secrete small proteins, of which some are effectors that promote infection. During colonization of the tomato xylem vessels the fungus Fusarium oxysporum f. sp. lycopersici (Fol secretes small proteins that are referred to as SIX (Secreted In Xylem proteins. Of these, Six1 (Avr3, Six3 (Avr2, Six5 and Six6 are required for full virulence, denoting them as effectors. To investigate their activities in the plant, the xylem sap proteome of plants inoculated with Fol wild-type or either AVR2, AVR3, SIX2, SIX5 or SIX6 knockout strains was analyzed with nano-Liquid Chromatography-Mass Spectrometry (nLC-MSMS. Compared to mock-inoculated sap 12 additional plant proteins appeared while 45 proteins were no longer detectable in the xylem sap of Fol-infected plants. Of the 285 proteins found in both uninfected and infected plants the abundance of 258 proteins changed significantly following infection. The xylem sap proteome of plants infected with four Fol effector knockout strains differed significantly from plants infected with wild-type Fol, while that of the SIX2-knockout inoculated plants remained unchanged. Besides an altered abundance of a core set of 24 differentially accumulated proteins (DAPs, each of the four effector knockout strains affected specifically the abundance of a subset of DAPs. Hence, Fol effectors have both unique and shared effects on the composition of the tomato xylem sap proteome.

Changes in wood density, wood anatomy and hydraulic properties of the xylem along the root-to-shoot flow path in tropical rainforest trees.

Science.gov (United States)

Schuldt, Bernhard; Leuschner, Christoph; Brock, Nicolai; Horna, Viviana

2013-02-01

It is generally assumed that the largest vessels are occurring in the roots and that vessel diameters and the related hydraulic conductance in the xylem are decreasing acropetally from roots to leaves. With this study in five tree species of a perhumid tropical rainforest in Sulawesi (Indonesia), we searched for patterns in hydraulic architecture and axial conductivity along the flow path from small-diameter roots through strong roots and the trunk to distal sun-canopy twigs. Wood density differed by not more than 10% across the different flow path positions in a species, and branch and stem wood density were closely related in three of the five species. Other than wood density, the wood anatomical and xylem hydraulic traits varied in dependence on the position along the flow path, but were unrelated to wood density within a tree. In contrast to reports from conifers and certain dicotyledonous species, we found a hump-shaped variation in vessel diameter and sapwood area--specific conductivity along the flow path in all five species with a maximum in the trunk and strong roots and minima in both small roots and twigs; the vessel size depended on the diameter of the organ. This pattern might be an adaptation to the perhumid climate with a low risk of hydraulic failure. Despite a similar mean vessel diameter in small roots and twigs, the two distal organs, hydraulically weighted mean vessel diameters were on average 30% larger in small roots, resulting in ∼ 85% higher empirical and theoretical specific conductivities. Relative vessel lumen area in percent of sapwood area decreased linearly by 70% from roots to twigs, reflecting the increase in sclerenchymatic tissue and tracheids in acropetal direction in the xylem. Vessel size was more closely related to the organ diameter than to the distance along the root-to-shoot flow path. We conclude that (i) the five co-occurring tree species show convergent patterns in their hydraulic architecture despite different growth

Arsenic speciation in xylem sap of cucumber (Cucumis sativus L.)

Energy Technology Data Exchange (ETDEWEB)

Mihucz, Victor G. [Joint Research Group of Environmental Chemistry of the Hungarian Academy of Sciences and L. Eoetvoes University, Budapest (Hungary); Hungarian Satellite Centre of Trace Elements Institute to UNESCO, Budapest (Hungary); Tatar, Eniko [Hungarian Satellite Centre of Trace Elements Institute to UNESCO, Budapest (Hungary); L. Eoetvoes University, Department of Inorganic and Analytical Chemistry, Budapest (Hungary); Virag, Istvan [L. Eoetvoes University, Department of Inorganic and Analytical Chemistry, Budapest (Hungary); Cseh, Edit; Fodor, Ferenc [L. Eoetvoes University, Department of Plant Physiology, Budapest (Hungary); Zaray, Gyula [Joint Research Group of Environmental Chemistry of the Hungarian Academy of Sciences and L. Eoetvoes University, Budapest (Hungary); Hungarian Satellite Centre of Trace Elements Institute to UNESCO, Budapest (Hungary); L. Eoetvoes University, Department of Inorganic and Analytical Chemistry, Budapest (Hungary)

2005-10-01

Flow injection analysis (FIA) and high-performance liquid chromatography double-focusing sector field inductively coupled plasma mass spectrometry (HPLC-DF-ICP-MS) were used for total arsenic determination and arsenic speciation of xylem sap of cucumber plants (Cucumis sativus L.) grown in hydroponics containing 2 {mu}mol dm{sup -3} arsenate or arsenite, respectively. Arsenite [As(III)], arsenate [As(V)] and dimethylarsinic acid (DMA) were identified in the sap of the plants. Arsenite was the predominant arsenic species in the xylem saps regardless of the type of arsenic treatment, and the following concentration order was determined: As(III) > As(V) > DMA. The amount of total As, calculated taking into consideration the mass of xylem sap collected, was almost equal for both treatments. Arsenite was taken up more easily by cucumber than arsenate. Partial oxidation of arsenite to arsenate (<10% in 48 h) was observed in the case of arsenite-containing nutrient solutions, which may explain the detection of arsenate in the saps of plants treated with arsenite. (orig.)

Changes in the Proteome of Xylem Sap in Brassica oleracea in Response to Fusarium oxysporum Stress.

Science.gov (United States)

Pu, Zijing; Ino, Yoko; Kimura, Yayoi; Tago, Asumi; Shimizu, Motoki; Natsume, Satoshi; Sano, Yoshitaka; Fujimoto, Ryo; Kaneko, Kentaro; Shea, Daniel J; Fukai, Eigo; Fuji, Shin-Ichi; Hirano, Hisashi; Okazaki, Keiichi

2016-01-01

Fusarium oxysporum f.sp. conlutinans (Foc) is a serious root-invading and xylem-colonizing fungus that causes yellowing in Brassica oleracea. To comprehensively understand the interaction between F. oxysporum and B. oleracea, composition of the xylem sap proteome of the non-infected and Foc-infected plants was investigated in both resistant and susceptible cultivars using liquid chromatography-tandem mass spectrometry (LC-MS/MS) after in-solution digestion of xylem sap proteins. Whole genome sequencing of Foc was carried out and generated a predicted Foc protein database. The predicted Foc protein database was then combined with the public B. oleracea and B. rapa protein databases downloaded from Uniprot and used for protein identification. About 200 plant proteins were identified in the xylem sap of susceptible and resistant plants. Comparison between the non-infected and Foc-infected samples revealed that Foc infection causes changes to the protein composition in B. oleracea xylem sap where repressed proteins accounted for a greater proportion than those of induced in both the susceptible and resistant reactions. The analysis on the proteins with concentration change > = 2-fold indicated a large portion of up- and down-regulated proteins were those acting on carbohydrates. Proteins with leucine-rich repeats and legume lectin domains were mainly induced in both resistant and susceptible system, so was the case of thaumatins. Twenty-five Foc proteins were identified in the infected xylem sap and 10 of them were cysteine-containing secreted small proteins that are good candidates for virulence and/or avirulence effectors. The findings of differential response of protein contents in the xylem sap between the non-infected and Foc-infected samples as well as the Foc candidate effectors secreted in xylem provide valuable insights into B. oleracea-Foc interactions.

Changes in the proteome of xylem sap in Brassica oleracea in response to Fusarium oxysporum stress

Directory of Open Access Journals (Sweden)

Zijing ePu

2016-02-01

Full Text Available Fusarium oxysporum f. sp. conlutinans (Foc is a serious root-invading and xylem-colonizing fungus that causes yellowing in Brassica oleracea. To comprehensively understand the interaction between F. oxysporum and B. oleracea, composition of the xylem sap proteome of the non-infected and Foc-infected plants was investigated in both resistant and susceptible cultivars using liquid chromatography-tandem mass spectrometry (LC-MS/MS after in-solution digestion of xylem sap proteins. Whole genome sequencing of Foc was carried out and generated a predicted Foc protein database. The predicted Foc protein database was then combined with the public B. oleracea and B. rapa protein databases downloaded from Uniprot and used for protein identification. About 200 plant proteins were identified in the xylem sap of susceptible and resistant plants. Comparison between the non-infected and Foc-infected samples revealed that Foc infection causes changes to the protein composition in B. oleracea xylem sap where repressed proteins accounted for a greater proportion than those of induced in both the susceptible and resistant reactions. The analysis on the proteins with concentration change >=2 fold indicated a large portion of up- and down-regulated proteins were those acting on carbohydrates. Proteins with leucine-rich repeats and legume lectin domains were mainly induced in both resistant and susceptible system, so was the case of thaumatins. Twenty-five Foc proteins were identified in the infected xylem sap and ten of them were cysteine-containing secreted small proteins that are good candidates for virulence and/or avirulence effectors. The findings of differential response of protein contents in the xylem sap between the non-infected and Foc-infected samples as well as the Foc candidate effectors secreted in xylem provide valuable insights into B. oleracea-Foc interactions.

Isolation of developing secondary xylem specific cellulose synthase ...

Indian Academy of Sciences (India)

The present study aimed at identifying developing secondary xylem specific cellulose synthase genes from .... the First strand cDNA synthesis kit (Fermentas, Pittsburgh,. USA). .... ing height of the rooted cutting, girth of the stem, leaf area.

The effector repertoire of Fusarium oxysporum determines the tomato xylem proteome composition following infection

NARCIS (Netherlands)

Gawehns, Fleur; Ma, Lisong; Bruning, Oskar; Houterman, Petra M.; Boeren, Sjef; Cornelissen, B.J.C.; Rep, Martijn; Takken, Frank L.W.

2015-01-01

Plant pathogens secrete small proteins, of which some are effectors that promote infection. During colonization of the tomato xylem vessels the fungus Fusarium oxysporum f.sp. lycopersici (Fol) secretes small proteins that are referred to as SIX (Secreted In Xylem) proteins. Of these, Six1

Intraspecific variation in the use of water sources by the circum-Mediterranean conifer Pinus halepensis.

Science.gov (United States)

Voltas, Jordi; Lucabaugh, Devon; Chambel, Maria Regina; Ferrio, Juan Pedro

2015-12-01

The relevance of interspecific variation in the use of plant water sources has been recognized in drought-prone environments. By contrast, the characterization of intraspecific differences in water uptake patterns remains elusive, although preferential access to particular soil layers may be an important adaptive response for species along aridity gradients. Stable water isotopes were analysed in soil and xylem samples of 56 populations of the drought-avoidant conifer Pinus halepensis grown in a common garden test. We found that most populations reverted to deep soil layers as the main plant water source during seasonal summer droughts. More specifically, we detected a clear geographical differentiation among populations in water uptake patterns even under relatively mild drought conditions (early autumn), with populations originating from more arid regions taking up more water from deep soil layers. However, the preferential access to deep soil water was largely independent of aboveground growth. Our findings highlight the high plasticity and adaptive relevance of the differential access to soil water pools among Aleppo pine populations. The observed ecotypic patterns point to the adaptive relevance of resource investment in deep roots as a strategy towards securing a source of water in dry environments for P. halepensis. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

The enigma of effective pathlength for 18O enrichment in leaf water of conifers

Science.gov (United States)

Roden, J. S.; Kahmen, A.; Buchmann, N. C.; Siegwolf, R. T.

2013-12-01

The stable isotopes of oxygen (δ18O) in tree ring cellulose provide valuable proxy information about past environments and climate. Mechanistic models have been used to clarify the important drivers of isotope fractionation and help interpret δ18O variation in tree rings. A critical component to these models is an estimate of leaf water enrichment. However, standard models seldom accurately predict 18O enrichment in conifer needles and Péclet corrections often require effective pathlengths (L) that seem unreasonable from the perspective of needle morphology (>0.5 m). To analyze the potential role of path length on the Péclet effect in conifers we carried out experiments in controlled environment chambers. We exposed seedlings of six species of conifer (Abies alba, Larix decidua, Picea abies, Pinus cembra, P. sylvestris, Taxus bacata), that differ in needle morphology, to four different vapor pressure deficits (VPD), in order to modify transpiration rates (E) and leaf water 18O enrichment. Environmental and δ18O data (leaf, stem and chamber water vapor) were collected to parameterize leaf water models. Cross-sections of needles were sampled for an analysis of needle anatomy. Conifer needles have a single strand of vascular tissue making pathlength determinations through anatomical assessments possible. The six species differed in mesophyll distance (measured from endodermis to epidermis) and cell number, with Pinus and Picea species having the shortest distance and Abies and Taxus the longest (flat needle morphology). Other anatomical measures (transfusion distance, cell size etc.) did not differ significantly. A suberized strip was apparent in the endodermis of all species except Taxus and Abies. Conifer needles have a large proportion (from 0.2 to 0.4) of needle cross-sectional area in vascular tissues that may not be subject to evaporative enrichment. As expected, leaf water δ18O and E responded strongly to VPD and standard models (Craig

Dissolved atmospheric gas in xylem sap measured with membrane inlet mass spectrometry.

Science.gov (United States)

Schenk, H Jochen; Espino, Susana; Visser, Ate; Esser, Bradley K

2016-04-01

A new method is described for measuring dissolved gas concentrations in small volumes of xylem sap using membrane inlet mass spectrometry. The technique can be used to determine concentrations of atmospheric gases, such as argon, as reported here, or for any dissolved gases and their isotopes for a variety of applications, such as rapid detection of trace gases from groundwater only hours after they were taken up by trees and rooting depth estimation. Atmospheric gas content in xylem sap directly affects the conditions and mechanisms that allow for gas removal from xylem embolisms, because gas can dissolve into saturated or supersaturated sap only under gas pressure that is above atmospheric pressure. The method was tested for red trumpet vine, Distictis buccinatoria (Bignoniaceae), by measuring atmospheric gas concentrations in sap collected at times of minimum and maximum daily temperature and during temperature increase and decline. Mean argon concentration in xylem sap did not differ significantly from saturation levels for the temperature and pressure conditions at any time of collection, but more than 40% of all samples were supersaturated, especially during the warm parts of day. There was no significant diurnal pattern, due to high variability between samples. © 2015 John Wiley & Sons Ltd.

Growth of Verticillium longisporum in Xylem Sap of Brassica napus is Independent from Cultivar Resistance but Promoted by Plant Aging.

Science.gov (United States)

Lopisso, Daniel Teshome; Knüfer, Jessica; Koopmann, Birger; von Tiedemann, Andreas

2017-09-01

As Verticillium stem striping of oilseed rape (OSR), a vascular disease caused by Verticillium longisporum, is extending into new geographic regions and no control with fungicides exists, the demand for understanding mechanisms of quantitative resistance increases. Because V. longisporum is strictly limited to the xylem and resistance is expressed in the systemic stage post root invasion, we investigated a potential antifungal role of soluble constituents and nutritional conditions in xylem sap as determinants of cultivar resistance of OSR to V. longisporum. Assessment of biometric and molecular genetic parameters applied to describe V. longisporum resistance (net area under disease progress curve, stunting, stem thickness, plant biomass, and V. longisporum DNA content) showed consistent susceptibility of cultivar 'Falcon' in contrast to two resistant genotypes, 'SEM' and 'Aviso'. Spectrophotometric analysis revealed a consistently stronger in vitro growth of V. longisporum in xylem sap extracted from OSR compared with the water control. Further comparisons of fungal growth in xylem sap of different cultivars revealed the absence of constitutive or V. longisporum induced antifungal activity in the xylem sap of resistant versus susceptible genotypes. The similar growth of V. longisporum in xylem sap, irrespective of cultivar, infection with V. longisporum and xylem sap filtration, was correlated with about equal amounts of total soluble proteins in xylem sap from these treatments. Interestingly, compared with younger plants, xylem sap from older plants induced significantly stronger fungal growth. Growth enhancement of V. longisporum in xylem sap of aging plants was reflected by increased contents of carbohydrates, which was consistent in mock or V. longisporum-infected plants and independent from cultivar resistance. The improved nutritional conditions in the xylem of more mature plants may explain the late appearance of disease symptoms, which are observed only in

Proteomics approach to identify unique xylem sap proteins in Pierce's disease-tolerant Vitis species.

Science.gov (United States)

Basha, Sheikh M; Mazhar, Hifza; Vasanthaiah, Hemanth K N

2010-03-01

Pierce's disease (PD) is a destructive bacterial disease of grapes caused by Xylella fastidiosa which is xylem-confined. The tolerance level to this disease varies among Vitis species. Our research was aimed at identifying unique xylem sap proteins present in PD-tolerant Vitis species. The results showed wide variation in the xylem sap protein composition, where a set of polypeptides with pI between 4.5 and 4.7 and M(r) of 31 kDa were present in abundant amount in muscadine (Vitis rotundifolia, PD-tolerant), in reduced levels in Florida hybrid bunch (Vitis spp., PD-tolerant) and absent in bunch grapes (Vitis vinifera, PD-susceptible). Liquid chromatography/mass spectrometry/mass spectrometry analysis of these proteins revealed their similarity to beta-1, 3-glucanase, peroxidase, and a subunit of oxygen-evolving enhancer protein 1, which are known to play role in defense and oxygen generation. In addition, the amount of free amino acids and soluble sugars was found to be significantly lower in xylem sap of muscadine genotypes compared to V. vinifera genotypes, indicating that the higher nutritional value of bunch grape sap may be more suitable for Xylella growth. These data suggest that the presence of these unique proteins in xylem sap is vital for PD tolerance in muscadine and Florida hybrid bunch grapes.

Surface tension phenomena in the xylem sap of three diffuse porous temperate tree species

Science.gov (United States)

K. K. Christensen-Dalsgaard; M. T. Tyree; P. G. Mussone

2011-01-01

In plant physiology models involving bubble nucleation, expansion or elimination, it is typically assumed that the surface tension of xylem sap is equal to that of pure water, though this has never been tested. In this study we collected xylem sap from branches of the tree species Populus tremuloides, Betula papyrifera and Sorbus...

Xylem-to-phloem transfer of boron in broccoli and lupin during early reproductive growth

Energy Technology Data Exchange (ETDEWEB)

Shelp, B J; Kitheka, A M; Cauwenberghe, O.R. Van [Univ. of Guelph, Dept. of Horticultural Science, Guelph, ON (Canada); Vanderpool, R A [Grand Forks Human Nutrition Research Center, Agricultural Research service, Grand Forks, ND (United States); Spiers, G A [Univ. of Guelph, Dept. of Land Resource Science, Guelph, ON (Canada)

1998-12-01

The aim of this study was to test the hypothesis that newly-acquired boron (B) undergoes rapid xylem-to-phloem transfer in plants with restricted mobility. Analysis of the element accumulation and water usage by shoots of intact broccoli (Brassica oleracea var. italica Plenck cv. Commander) and lupin (Lupinus albus L. cv. Ultra) plants provided with a non-deficient supply of B, revealed that the concentration of various mineral elements (K, P, Mg, Ca, B, Fe, Zn, Mo, Cu, Mn) in xylem sap of intact plants ranged from 0.3 {mu}M to 3.5 mM, with B being present at 2.9-3.5 {mu}M. For each element assayed, the concentration was higher in phloem exudate (1.6 {mu}M to 91 mM) than in xylem sap; B was present at about 0.4 mM. Intact broccoli and lupin plants or detached transpiring broccoli shoots were supplied simultaneously with enriched {sup 10}B, strontium (a xylem marker) and rubidium (a xylem/phloem marker) during early reproductive growth. The contents of these three compounds were determined in foliage and florets or fruits as a function of time (i.e. up to 12 h and 4 days for broccoli and lupin plants, respectively), and the content in florets or fruits was expressed as a percent of the total recovered. In general, the percent recovery of both {sup 10}B and rubidium in florets or fruits was similar and markedly greater than that for strontium, even at the earliest harvest times (within 2 h for broccoli and 1 day for lupin). The data indicate that in plants with restricted B mobility, B is supplied to sink tissues in the phloem, and the extent of B xylem-to-phloem transfer is closely determined by current uptake. (au) 35 refs.

Xylem-to-phloem transfer of boron in broccoli and lupin during early reproductive growth

International Nuclear Information System (INIS)

Shelp, B.J.; Kitheka, A.M.; Cauwenberghe, O.R. Van; Vanderpool, R.A.; Spiers, G.A.

1998-01-01

The aim of this study was to test the hypothesis that newly-acquired boron (B) undergoes rapid xylem-to-phloem transfer in plants with restricted mobility. Analysis of the element accumulation and water usage by shoots of intact broccoli (Brassica oleracea var. italica Plenck cv. Commander) and lupin (Lupinus albus L. cv. Ultra) plants provided with a non-deficient supply of B, revealed that the concentration of various mineral elements (K, P, Mg, Ca, B, Fe, Zn, Mo, Cu, Mn) in xylem sap of intact plants ranged from 0.3 μM to 3.5 mM, with B being present at 2.9-3.5 μM. For each element assayed, the concentration was higher in phloem exudate (1.6 μM to 91 mM) than in xylem sap; B was present at about 0.4 mM. Intact broccoli and lupin plants or detached transpiring broccoli shoots were supplied simultaneously with enriched 10 B, strontium (a xylem marker) and rubidium (a xylem/phloem marker) during early reproductive growth. The contents of these three compounds were determined in foliage and florets or fruits as a function of time (i.e. up to 12 h and 4 days for broccoli and lupin plants, respectively), and the content in florets or fruits was expressed as a percent of the total recovered. In general, the percent recovery of both 10 B and rubidium in florets or fruits was similar and markedly greater than that for strontium, even at the earliest harvest times (within 2 h for broccoli and 1 day for lupin). The data indicate that in plants with restricted B mobility, B is supplied to sink tissues in the phloem, and the extent of B xylem-to-phloem transfer is closely determined by current uptake. (au)

Ungulate exclusion, conifer thinning and mule deer forage in northeastern New Mexico

Science.gov (United States)

Kramer, David W.; Sorensen, Grant E.; Taylor, Chase A.; Cox, Robert D.; Gipson, Philip S.; Cain, James W.

2015-01-01

The southwestern United States has experienced expansion of conifer species (Juniperus spp. and Pinus ponderosa) into areas of semi-arid grassland over the past century. The expansion of conifers can limit palatable forage and reduce grass and forb communities. Conifer species are sometimes thinned through hydraulic mulching or selective cutting. We assessed the effects of these treatments on mule deer (Odocoileus hemionus) habitat in northeastern New Mexico to determine if conifer thinning improved cover of preferred forage species for mule deer in areas with and without ungulates. We measured plant cover and occurrence of preferred forage species in the summers of 2011 and 2012. An ongoing regional drought probably reduced vegetation response, with preferred forage species and herbaceous cover responding to conifer thinning or ungulate exclusion immediately following treatment, but not the following year. In 2011, areas that received thinning treatments had a higher abundance of preferred forage when compared to sites with no treatment. Grass coverage exhibited an immediate response in 2011, with ungulate exclosures containing 8% more coverage than areas without exclosures. The results suggest that conifer thinning and ungulate exclusion may elicit a positive response, however in the presence of drought; the positive effects are only short-term.

Two Complementary Mechanisms Underpin Cell Wall Patterning during Xylem Vessel Development.

Science.gov (United States)

Schneider, Rene; Tang, Lu; Lampugnani, Edwin R; Barkwill, Sarah; Lathe, Rahul; Zhang, Yi; McFarlane, Heather E; Pesquet, Edouard; Niittyla, Totte; Mansfield, Shawn D; Zhou, Yihua; Persson, Staffan

2017-10-01

The evolution of the plant vasculature was essential for the emergence of terrestrial life. Xylem vessels are solute-transporting elements in the vasculature that possess secondary wall thickenings deposited in intricate patterns. Evenly dispersed microtubule (MT) bands support the formation of these wall thickenings, but how the MTs direct cell wall synthesis during this process remains largely unknown. Cellulose is the major secondary wall constituent and is synthesized by plasma membrane-localized cellulose synthases (CesAs) whose catalytic activity propels them through the membrane. We show that the protein CELLULOSE SYNTHASE INTERACTING1 (CSI1)/POM2 is necessary to align the secondary wall CesAs and MTs during the initial phase of xylem vessel development in Arabidopsis thaliana and rice ( Oryza sativa ). Surprisingly, these MT-driven patterns successively become imprinted and sufficient to sustain the continued progression of wall thickening in the absence of MTs and CSI1/POM2 function. Hence, two complementary principles underpin wall patterning during xylem vessel development. © 2017 American Society of Plant Biologists. All rights reserved.

Targeted isolation, sequence assembly and characterization of two white spruce (Picea glauca BAC clones for terpenoid synthase and cytochrome P450 genes involved in conifer defence reveal insights into a conifer genome

Directory of Open Access Journals (Sweden)

Ritland Carol

2009-08-01

Full Text Available Abstract Background Conifers are a large group of gymnosperm trees which are separated from the angiosperms by more than 300 million years of independent evolution. Conifer genomes are extremely large and contain considerable amounts of repetitive DNA. Currently, conifer sequence resources exist predominantly as expressed sequence tags (ESTs and full-length (FLcDNAs. There is no genome sequence available for a conifer or any other gymnosperm. Conifer defence-related genes often group into large families with closely related members. The goals of this study are to assess the feasibility of targeted isolation and sequence assembly of conifer BAC clones containing specific genes from two large gene families, and to characterize large segments of genomic DNA sequence for the first time from a conifer. Results We used a PCR-based approach to identify BAC clones for two target genes, a terpene synthase (3-carene synthase; 3CAR and a cytochrome P450 (CYP720B4 from a non-arrayed genomic BAC library of white spruce (Picea glauca. Shotgun genomic fragments isolated from the BAC clones were sequenced to a depth of 15.6- and 16.0-fold coverage, respectively. Assembly and manual curation yielded sequence scaffolds of 172 kbp (3CAR and 94 kbp (CYP720B4 long. Inspection of the genomic sequences revealed the intron-exon structures, the putative promoter regions and putative cis-regulatory elements of these genes. Sequences related to transposable elements (TEs, high complexity repeats and simple repeats were prevalent and comprised approximately 40% of the sequenced genomic DNA. An in silico simulation of the effect of sequencing depth on the quality of the sequence assembly provides direction for future efforts of conifer genome sequencing. Conclusion We report the first targeted cloning, sequencing, assembly, and annotation of large segments of genomic DNA from a conifer. We demonstrate that genomic BAC clones for individual members of multi-member gene

Targeted isolation, sequence assembly and characterization of two white spruce (Picea glauca) BAC clones for terpenoid synthase and cytochrome P450 genes involved in conifer defence reveal insights into a conifer genome.

Science.gov (United States)

Hamberger, Björn; Hall, Dawn; Yuen, Mack; Oddy, Claire; Hamberger, Britta; Keeling, Christopher I; Ritland, Carol; Ritland, Kermit; Bohlmann, Jörg

2009-08-06

Conifers are a large group of gymnosperm trees which are separated from the angiosperms by more than 300 million years of independent evolution. Conifer genomes are extremely large and contain considerable amounts of repetitive DNA. Currently, conifer sequence resources exist predominantly as expressed sequence tags (ESTs) and full-length (FL)cDNAs. There is no genome sequence available for a conifer or any other gymnosperm. Conifer defence-related genes often group into large families with closely related members. The goals of this study are to assess the feasibility of targeted isolation and sequence assembly of conifer BAC clones containing specific genes from two large gene families, and to characterize large segments of genomic DNA sequence for the first time from a conifer. We used a PCR-based approach to identify BAC clones for two target genes, a terpene synthase (3-carene synthase; 3CAR) and a cytochrome P450 (CYP720B4) from a non-arrayed genomic BAC library of white spruce (Picea glauca). Shotgun genomic fragments isolated from the BAC clones were sequenced to a depth of 15.6- and 16.0-fold coverage, respectively. Assembly and manual curation yielded sequence scaffolds of 172 kbp (3CAR) and 94 kbp (CYP720B4) long. Inspection of the genomic sequences revealed the intron-exon structures, the putative promoter regions and putative cis-regulatory elements of these genes. Sequences related to transposable elements (TEs), high complexity repeats and simple repeats were prevalent and comprised approximately 40% of the sequenced genomic DNA. An in silico simulation of the effect of sequencing depth on the quality of the sequence assembly provides direction for future efforts of conifer genome sequencing. We report the first targeted cloning, sequencing, assembly, and annotation of large segments of genomic DNA from a conifer. We demonstrate that genomic BAC clones for individual members of multi-member gene families can be isolated in a gene-specific fashion. The

Coordination and transport of water and carbohydrates in the coupled soil-root-xylem-phloem leaf system

Science.gov (United States)

Katul, Gabriel; Huang, Cheng-Wei

2017-04-01

In response to varying environmental conditions, stomatal pores act as biological valves that dynamically adjust their size thereby determining the rate of CO2 assimilation and water loss (i.e., transpiration) to the atmosphere. Although the significance of this biotic control on gas exchange is rarely disputed, representing parsimoniously all the underlying mechanisms responsible for stomatal kinetics remain a subject of some debate. It has been conjectured that stomatal control in seed plants (i.e., angiosperm and gymnosperm) represents a compromise between biochemical demand for CO2 and prevention of excessive water loss. This view has been amended at the whole-plant level, where xylem hydraulics and sucrose transport efficiency in phloem appear to impose additional constraints on gas exchange. If such additional constraints impact stomatal opening and closure, then seed plants may have evolved coordinated photosynthetic-hydraulic-sugar transporting machinery that confers some competitive advantages in fluctuating environmental conditions. Thus, a stomatal optimization model that explicitly considers xylem hydraulics and maximum sucrose transport is developed to explore this coordination in the leaf-xylem-phloem system. The model is then applied to progressive drought conditions. The main findings from the model calculations are that (1) the predicted stomatal conductance from the conventional stomatal optimization theory at the leaf and the newly proposed models converge, suggesting a tight coordination in the leaf-xylem-phloem system; (2) stomatal control is mainly limited by the water supply function of the soil-xylem hydraulic system especially when the water flux through the transpiration stream is significantly larger than water exchange between xylem and phloem; (3) thus, xylem limitation imposed on the supply function can be used to differentiate species with different water use strategy across the spectrum of isohydric to anisohydric behavior.

Phloem as Capacitor: Radial Transfer of Water into Xylem of Tree Stems Occurs via Symplastic Transport in Ray Parenchyma[OPEN

Science.gov (United States)

Renard, Justine; Tjoelker, Mark G.; Salih, Anya

2015-01-01

The transfer of water from phloem into xylem is thought to mitigate increasing hydraulic tension in the vascular system of trees during the diel cycle of transpiration. Although a putative plant function, to date there is no direct evidence of such water transfer or the contributing pathways. Here, we trace the radial flow of water from the phloem into the xylem and investigate its diel variation. Introducing a fluorescent dye (0.1% [w/w] fluorescein) into the phloem water of the tree species Eucalyptus saligna allowed localization of the dye in phloem and xylem tissues using confocal laser scanning microscopy. Our results show that the majority of water transferred between the two tissues is facilitated via the symplast of horizontal ray parenchyma cells. The method also permitted assessment of the radial transfer of water during the diel cycle, where changes in water potential gradients between phloem and xylem determine the extent and direction of radial transfer. When injected during the morning, when xylem water potential rapidly declined, fluorescein was translocated, on average, farther into mature xylem (447 ± 188 µm) compared with nighttime, when xylem water potential was close to zero (155 ± 42 µm). These findings provide empirical evidence to support theoretical predictions of the role of phloem-xylem water transfer in the hydraulic functioning of plants. This method enables investigation of the role of phloem tissue as a dynamic capacitor for water storage and transfer and its contribution toward the maintenance of the functional integrity of xylem in trees. PMID:25588734

Interaction of xylem and phloem during exudation and wound occlusion in Cucurbita maxima.

Science.gov (United States)

Zimmermann, Matthias R; Hafke, Jens B; van Bel, Aart J E; Furch, Alexandra C U

2013-01-01

Collection of cucurbit exudates from cut petioles has been a powerful tool for gaining knowledge on phloem sap composition without full notion of the complex exudation mechanism. Only few publications explicitly mentioned that exudates were collected from the basal side of the cut, which exudes more copiously than the apical side. This is surprising since only exudation from the apical side is supposedly driven by phloem pressure gradients. Composition of carbohydrates and pH values at both wounding sides are equal, whereas protein concentration is higher at the basal side. Apparently, exudation is far more complex than just the delivery of phloem sap. Xylem involvement is indicated by lower protein concentrations after elimination of root pressure. Moreover, dye was sucked into xylem vessels owing to relaxation of negative pressure after cutting. The lateral water efflux from the vessels increases turgor of surrounding cells including sieve elements. Simultaneously, detached parietal proteins (PP1/PP2) induce occlusion of sieve plates and cover wound surface. If root pressure is strong enough, pure xylem sap can be collected after removal of the occlusion plug at the wound surface. The present findings provide a mechanism of sap exudation in Cucurbita maxima, in which the contribution of xylem water is integrated. © 2012 Blackwell Publishing Ltd.

Spectral changes in conifers subjected to air pollution and water stress: Experimental studies

Science.gov (United States)

Westman, Walter E.; Price, Curtis V.

1988-01-01

The roles of leaf anatomy, moisture and pigment content, and number of leaf layers on spectral reflectance in healthy, pollution-stressed, and water-stressed conifer needles were examined experimentally. Jeffrey pine (Pinus jeffreyi) and giant sequoia (Sequoiadendron gigantea) were exposed to ozone and acid mist treatments in fumigation chambers; red pine (Pinus resinosa) needles were artificially dried. Infrared reflectance from stacked needles rose with free water loss. In an air-drying experiment, cell volume reductions induced by loss of turgor caused near-infrared reflectance (TM band 4) to drop after most free water was lost. Under acid mist fumigation, stunting of tissue development similarly reduced band 4 reflectance. Both artificial drying and pollutant fumigation caused a blue shift of the red edge of spectral reflectance curves in conifers, attributable to chlorophyll denaturation. Thematic mapper band ratio 4/3 fell and 5/4 rose with increasing pollution stress on artificial drying. Loss of water by air-drying, freeze-drying, or oven-drying enhanced spectral features, due in part to greater scattering and reduced water absorption. Grinding of the leaf tissue further enhanced the spectral features by increasing reflecting surfaces and path length. In a leaf-stacking experiment, an asymptote in visible and infrared reflectance was reached at 7-8 needle layers of red pine.

Three causes of variation in the photochemical reflectance index (PRI) in evergreen conifers.

Science.gov (United States)

Wong, Christopher Y S; Gamon, John A

2015-04-01

The photochemical reflectance index (PRI) reflects diurnal xanthophyll cycle activity and is also influenced by seasonally changing carotenoid : Chl pigment ratios. Both changing pigment pools and xanthophyll cycle activity contribute to photoprotection in evergreen conifers exposed to boreal winters, but they operate over different timescales, and their relative contribution to the PRI signal has often been unclear. To clarify these responses and their contribution to the PRI signal, leaf PRI, pigment composition, temperature and irradiance were monitored over 2 yr for two evergreen conifers (Pinus contorta and Pinus ponderosa) in a boreal climate. PRI was affected by three distinct processes operating over different timescales and exhibiting contrasting spectral responses. Over the 2 yr study period, the greatest change in PRI resulted from seasonally changing carotenoid : Chl pigment ratios, followed by a previously unreported shifting leaf albedo during periods of deep cold. Remarkably, the smallest change was attributable to the xanthophyll cycle. To properly distinguish these three effects, interpretation of PRI must consider temporal context, physiological responses to evolving environmental conditions, and spectral response. Consideration of the separate mechanisms affecting PRI over different timescales could greatly improve efforts to monitor changing photosynthetic activity using optical remote sensing. © 2014 The Authors New Phytologist © 2014 New Phytologist Trust.

Physical analysis of the process of cavitation in xylem sap.

Science.gov (United States)

Shen, Fanyi; Gao, Rongfu; Liu, Wenji; Zhang, Wenjie

2002-06-01

Recent studies have confirmed that cavitation in xylem is caused by air bubbles. We analyzed expansion of a preexistent bubble adhering to a crack in a conduit wall and a bubble formed by the passage of air through a pore of a pit membrane, a process known as air seeding. We consider that there are two equilibrium states for a very small air bubble in the xylem: one is temporarily stable with a bubble radius r1 at point s1 on the curve P(r) relating pressure within the bubble (P) with bubble radius (r); the other is unstable with a bubble radius r2 at point s2 on Pr (where r1 equilibrium state, the bubble collapse pressure (2sigma/r, where sigma is surface tension of water) is balanced by the pressure difference across its surface. In the case of a bubble from a crack in a conduit wall, which is initially at point s1, expansion will occur steadily as water potential decreases. The bubble will burst only if the xylem pressure drops below a threshold value. A formula giving the threshold pressure for bubble bursting is proposed. In the case of an air seed entering a xylem conduit through a pore in a pit membrane, its initial radius may be r2 (i.e., the radius of the pore by which the air seed entered the vessel) at point s2 on Pr. Because the bubble is in an unstable equilibrium when entering the conduit, it can either expand or contract to point s1. As water vaporizes into the air bubble at s2, P rises until it exceeds the gas pressure that keeps the bubble in equilibrium, at which point the bubble will burst and induce a cavitation event in accordance with the air-seeding hypothesis. However, other possible perturbations could make the air-seeded bubble contract to s1, in which case the bubble will burst at a threshold pressure proposed for a bubble expanding from a crack in a conduit wall. For this reason some cavitation events may take place at a xylem threshold pressure (Pl'*) other than that determined by the formula, Plp'* = -2sigma/rp, proposed by Sperry and

Metabolomics of tomato xylem sap during bacterial wilt reveals Ralstonia solanacearum produces abundant putrescine, a metabolite that accelerates wilt disease

NARCIS (Netherlands)

Lowe-Power, Tiffany M.; Hendrich, Connor G.; Roepenack-Lahaye, von Edda; Li, Bin; Wu, Dousheng; Mitra, Raka; Dalsing, Beth L.; Ricca, Patrizia; Naidoo, Jacinth; Cook, David; Jancewicz, Amy; Masson, Patrick; Thomma, Bart; Lahaye, Thomas; Michael, Anthony J.; Allen, Caitilyn

2018-01-01

Ralstonia solanacearum thrives in plant xylem vessels and causes bacterial wilt disease despite the low nutrient content of xylem sap. We found that R. solanacearum manipulates its host to increase nutrients in tomato xylem sap, enabling it to grow better in sap from infected plants than in sap from

A closed-form solution for steady-state coupled phloem/xylem flow using the Lambert-W function.

Science.gov (United States)

Hall, A J; Minchin, P E H

2013-12-01

A closed-form solution for steady-state coupled phloem/xylem flow is presented. This incorporates the basic Münch flow model of phloem transport, the cohesion model of xylem flow, and local variation in the xylem water potential and lateral water flow along the transport pathway. Use of the Lambert-W function allows this solution to be obtained under much more general and realistic conditions than has previously been possible. Variation in phloem resistance (i.e. viscosity) with solute concentration, and deviations from the Van't Hoff expression for osmotic potential are included. It is shown that the model predictions match those of the equilibrium solution of a numerical time-dependent model based upon the same mechanistic assumptions. The effect of xylem flow upon phloem flow can readily be calculated, which has not been possible in any previous analytical model. It is also shown how this new analytical solution can handle multiple sources and sinks within a complex architecture, and can describe competition between sinks. The model provides new insights into Münch flow by explicitly including interactions with xylem flow and water potential in the closed-form solution, and is expected to be useful as a component part of larger numerical models of entire plants. © 2013 John Wiley & Sons Ltd.

Plant GSK3 proteins regulate xylem cell differentiation downstream of TDIF-TDR signalling

Science.gov (United States)

Kondo, Yuki; Ito, Tasuku; Nakagami, Hirofumi; Hirakawa, Yuki; Saito, Masato; Tamaki, Takayuki; Shirasu, Ken; Fukuda, Hiroo

2014-03-01

During plant radial growth typically seen in trees, procambial and cambial cells act as meristematic cells in the vascular system to self-proliferate and differentiate into xylem cells. These two processes are regulated by a signalling pathway composed of a peptide ligand and its receptor; tracheary element differentiation inhibitory factor (TDIF) and TDIF RECEPTOR (TDR). Here we show that glycogen synthase kinase 3 proteins (GSK3s) are crucial downstream components of the TDIF signalling pathway suppressing xylem differentiation from procambial cells. TDR interacts with GSK3s at the plasma membrane and activates GSK3s in a TDIF-dependent fashion. Consistently, a specific inhibitor of plant GSK3s strongly induces xylem cell differentiation through BRI1-EMS SUPPRESSOR 1 (BES1), a well-known target transcription factor of GSK3s. Our findings provide insight into the regulation of cell fate determination in meristem maintenance.

Optical measurement of stem xylem vulnerability

OpenAIRE

Brodribb, Timothy J.; Carriqui, Marc; Delzon, Sylvain; Lucani, Christopher

2017-01-01

The vulnerability of plant water transport tissues to a loss of function by cavitation during water stress is a key indicator of the survival capabilities of plant species during drought. Quantifying this important metric has been greatly advanced by noninvasive techniques that allow embolisms to be viewed directly in the vascular system. Here, we present a new method for evaluating the spatial and temporal propagation of embolizing bubbles in the stem xylem during imposed water stress. We de...

Effects of Xylem-Sap Composition on Glassy-Winged Sharpshooter (Hemiptera: Cicadellidae) Egg Maturation on High- and Low-Quality Host Plants.

Science.gov (United States)

Sisterson, Mark S; Wallis, Christopher M; Stenger, Drake C

2017-04-01

Glassy-winged sharpshooters must feed as adults to produce mature eggs. Cowpea and sunflower are both readily accepted by the glassy-winged sharpshooter for feeding, but egg production on sunflower was reported to be lower than egg production on cowpea. To better understand the role of adult diet in egg production, effects of xylem-sap chemistry on glassy-winged sharpshooter egg maturation was compared for females confined to cowpea and sunflower. Females confined to cowpea consumed more xylem-sap than females held on sunflower. In response, females held on cowpea produced more eggs, had heavier bodies, and greater lipid content than females held on sunflower. Analysis of cowpea and sunflower xylem-sap found that 17 of 19 amino acids were more concentrated in cowpea xylem-sap than in sunflower xylem-sap. Thus, decreased consumption of sunflower xylem-sap was likely owing to perceived lower quality, with decreased egg production owing to a combination of decreased feeding and lower return per unit volume of xylem-sap consumed. Examination of pairwise correlation coefficients among amino acids indicated that concentrations of several amino acids within a plant species were correlated. Principal component analyses identified latent variables describing amino acid composition of xylem-sap. For females held on cowpea, egg maturation was affected by test date, volume of excreta produced, and principal components describing amino acid composition of xylem-sap. Principal component analyses aided in identifying amino acids that were positively or negatively associated with egg production, although determining causality with respect to key nutritional requirements for glassy-winged sharpshooter egg production will require additional testing. Published by Oxford University Press on behalf of Entomological Society of America 2017. This work is written by US Government employees and is in the public domain in the US.

Synchronisms and correlations of spring phenology between apical and lateral meristems in two boreal conifers.

Science.gov (United States)

Antonucci, Serena; Rossi, Sergio; Deslauriers, Annie; Lombardi, Fabio; Marchetti, Marco; Tognetti, Roberto

2015-10-01

Phenological synchronisms between apical and lateral meristems could clarify some aspects related to the physiological relationships among the different organs of trees. This study correlated the phenological phases of bud development and xylem differentiation during spring 2010-14 in balsam fir (Abies balsamea Mill.) and black spruce [(Picea mariana Mill. (BSP)] of the Monts-Valin National Park (Quebec, Canada) by testing the hypothesis that bud development occurs after the reactivation of xylem growth. From May to September, we conducted weekly monitoring of xylem differentiation using microcores and bud development with direct observations on terminal branches. Synchronism between the beginning of bud development and xylem differentiation was found in both species with significant correlations between the phases of bud and xylem phenology. Degree-day sum was more appropriate in assessing the date of bud growth resumption, while thermal thresholds were more suitable for cambium phenology. Our results provide new knowledge on the dynamics of spring phenology and novel information on the synchronisms between two meristems in coniferous trees. The study demonstrates the importance of precisely defining the phases of bud development in order to correctly analyse the relationships with xylem phenology. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

CONIFERS: a neutronics code for reactors with channels

International Nuclear Information System (INIS)

Davis, R.S.

1977-04-01

CONIFERS is a neutronics code for nuclear reactors whose fuel is in channels that are separated from each other by several neutron mean-free-path lengths of moderator. It can treat accurately situations in which the usual homogenized-cell diffusion equation becomes inaccurate, but is more economical than other advanced methods such as response-matrix and source-sink formalisms. CONIFERS uses exact solutions of the neutron diffusion equation within each cell. It allows for the breakdown of this equation near a channel by means of data that almost any cell code can supply. It uses the results of these cell analyses in a reactor equations set that is as readily solvable as the familiar finite-difference equations set. CONIFERS can model almost any configuration of channels and other structures in two or three dimensions. It can use any number of energy groups and any reactivity scales, including scales based on control operations. It is also flexible from a programming point of view, and has convenient input and output provisions. (author)

Transcriptome analysis of the phytobacterium Xylella fastidiosa growing under xylem-based chemical conditions.

Science.gov (United States)

Ciraulo, Maristela Boaceff; Santos, Daiene Souza; Rodrigues, Ana Claudia de Freitas Oliveira; de Oliveira, Marcus Vinícius; Rodrigues, Tiago; de Oliveira, Regina Costa; Nunes, Luiz R

2010-01-01

Xylella fastidiosa is a xylem-limited bacterium responsible for important plant diseases, like citrus-variegated chlorosis (CVC) and grapevine Pierce's disease (PD). Interestingly, in vitro growth of X. fastidiosa in chemically defined media that resemble xylem fluid has been achieved, allowing studies of metabolic processes used by xylem-dwelling bacteria to thrive in such nutrient-poor conditions. Thus, we performed microarray hybridizations to compare transcriptomes of X. fastidiosa cells grown in 3G10-R, a medium that resembles grape sap, and in Periwinkle Wilt (PW), the complex medium traditionally used to cultivate X. fastidiosa. We identified 299 transcripts modulated in response to growth in these media. Some 3G10R-overexpressed genes have been shown to be upregulated in cells directly isolated from infected plants and may be involved in plant colonization, virulence and environmental competition. In contrast, cells cultivated in PW show a metabolic switch associated with increased aerobic respiration and enhanced bacterial growth rates.

Transcriptome Analysis of the Phytobacterium Xylella fastidiosa Growing under Xylem-Based Chemical Conditions

Directory of Open Access Journals (Sweden)

Maristela Boaceff Ciraulo

2010-01-01

Full Text Available Xylella fastidiosa is a xylem-limited bacterium responsible for important plant diseases, like citrus-variegated chlorosis (CVC and grapevine Pierce's disease (PD. Interestingly, in vitro growth of X. fastidiosa in chemically defined media that resemble xylem fluid has been achieved, allowing studies of metabolic processes used by xylem-dwelling bacteria to thrive in such nutrient-poor conditions. Thus, we performed microarray hybridizations to compare transcriptomes of X. fastidiosa cells grown in 3G10-R, a medium that resembles grape sap, and in Periwinkle Wilt (PW, the complex medium traditionally used to cultivate X. fastidiosa. We identified 299 transcripts modulated in response to growth in these media. Some 3G10R-overexpressed genes have been shown to be upregulated in cells directly isolated from infected plants and may be involved in plant colonization, virulence and environmental competition. In contrast, cells cultivated in PW show a metabolic switch associated with increased aerobic respiration and enhanced bacterial growth rates.

Conifers have a unique small RNA silencing signature.

Science.gov (United States)

Dolgosheina, Elena V; Morin, Ryan D; Aksay, Gozde; Sahinalp, S Cenk; Magrini, Vincent; Mardis, Elaine R; Mattsson, Jim; Unrau, Peter J

2008-08-01

Plants produce small RNAs to negatively regulate genes, viral nucleic acids, and repetitive elements at either the transcriptional or post-transcriptional level in a process that is referred to as RNA silencing. While RNA silencing has been extensively studied across the different phyla of the animal kingdom (e.g., mouse, fly, worm), similar studies in the plant kingdom have focused primarily on angiosperms, thus limiting evolutionary studies of RNA silencing in plants. Here we report on an unexpected phylogenetic difference in the size distribution of small RNAs among the vascular plants. By extracting total RNA from freshly growing shoot tissue, we conducted a survey of small RNAs in 24 vascular plant species. We find that conifers, which radiated from the other seed-bearing plants approximately 260 million years ago, fail to produce significant amounts of 24-nucleotide (nt) RNAs that are known to guide DNA methylation and heterochromatin formation in angiosperms. Instead, they synthesize a diverse population of small RNAs that are exactly 21-nt long. This finding was confirmed by high-throughput sequencing of the small RNA sequences from a conifer, Pinus contorta. A conifer EST search revealed the presence of a novel Dicer-like (DCL) family, which may be responsible for the observed change in small RNA expression. No evidence for DCL3, an enzyme that matures 24-nt RNAs in angiosperms, was found. We hypothesize that the diverse class of 21-nt RNAs found in conifers may help to maintain organization of their unusually large genomes.

Diversity, Biocontrol, and Plant Growth Promoting Abilities of Xylem Residing Bacteria from Solanaceous Crops

Directory of Open Access Journals (Sweden)

Gauri A. Achari

2014-01-01

Full Text Available Eggplant (Solanum melongena L. is one of the solanaceous crops of economic and cultural importance and is widely cultivated in the state of Goa, India. Eggplant cultivation is severely affected by bacterial wilt caused by Ralstonia solanacearum that colonizes the xylem tissue. In this study, 167 bacteria were isolated from the xylem of healthy eggplant, chilli, and Solanum torvum Sw. by vacuum infiltration and maceration. Amplified rDNA restriction analysis (ARDRA grouped these xylem residing bacteria (XRB into 38 haplotypes. Twenty-eight strains inhibited growth of R. solanacearum and produced volatile and diffusible antagonistic compounds and plant growth promoting substances in vitro. Antagonistic strains XB86, XB169, XB177, and XB200 recorded a biocontrol efficacy greater than 85% against BW and exhibited 12%–22 % increase in shoot length in eggplant in the greenhouse screening. 16S rRNA based identification revealed the presence of 23 different bacterial genera. XRB with high biocontrol and plant growth promoting activities were identified as strains of Staphylococcus sp., Bacillus sp., Streptomyces sp., Enterobacter sp., and Agrobacterium sp. This study is the first report on identity of bacteria from the xylem of solanaceous crops having traits useful in cultivation of eggplant.

Better living through conifer removal: A demographic analysis of sage-grouse vital rates.

Directory of Open Access Journals (Sweden)

John P Severson

Full Text Available Sagebrush (Artemisia spp. obligate wildlife species such as the imperiled greater sage-grouse (Centrocercus urophasianus face numerous threats including altered ecosystem processes that have led to conifer expansion into shrub-steppe. Conifer removal is accelerating despite a lack of empirical evidence on grouse population response. Using a before-after-control-impact design at the landscape scale, we evaluated effects of conifer removal on two important demographic parameters, annual survival of females and nest survival, by monitoring 219 female sage-grouse and 225 nests in the northern Great Basin from 2010 to 2014. Estimates from the best treatment models showed positive trends in the treatment area relative to the control area resulting in an increase of 6.6% annual female survival and 18.8% nest survival relative to the control area by 2014. Using stochastic simulations of our estimates and published demographics, we estimated a 25% increase in the population growth rate in the treatment area relative to the control area. This is the first study to link sage-grouse demographics with conifer removal and supports recommendations to actively manage conifer expansion for sage-grouse conservation. Sage-grouse have become a primary catalyst for conservation funding to address conifer expansion in the West, and these findings have important implications for other ecosystem services being generated on the wings of species conservation.

Functional adjustments of xylem anatomy to climatic variability: insights from long-term Ilex aquifolium tree-ring series.

Science.gov (United States)

Rita, Angelo; Cherubini, Paolo; Leonardi, Stefano; Todaro, Luigi; Borghetti, Marco

2015-08-01

The present study assessed the effects of climatic conditions on radial growth and functional anatomical traits, including ring width, vessel size, vessel frequency and derived variables, i.e., potential hydraulic conductivity and xylem vulnerability to cavitation in Ilex aquifolium L. trees using long-term tree-ring time series obtained at two climatically contrasting sites, one mesic site in Switzerland (CH) and one drought-prone site in Italy (ITA). Relationships were explored by examining different xylem traits, and point pattern analysis was applied to investigate vessel clustering. We also used generalized additive models and bootstrap correlation functions to describe temperature and precipitation effects. Results indicated modified radial growth and xylem anatomy in trees over the last century; in particular, vessel frequency increased markedly at both sites in recent years, and all xylem traits examined, with the exception of xylem cavitation vulnerability, were higher at the CH mesic compared with the ITA drought site. A significant vessel clustering was observed at the ITA site, which could contribute to an enhanced tolerance to drought-induced embolism. Flat and negative relationships between vessel size and ring width were observed, suggesting carbon was not allocated to radial growth under conditions which favored stem water conduction. Finally, in most cases results indicated that climatic conditions influenced functional anatomical traits more substantially than tree radial growth, suggesting a crucial role of functional xylem anatomy in plant acclimation to future climatic conditions. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Forming a structure of the CoNiFe alloys by X-ray irradiation

Science.gov (United States)

Valko, Natalia; Kasperovich, Andrey; Koltunowicz, Tomasz N.

The experimental data of electrodeposition kinetics researches and structure formation of ternary CoNiFe alloys deposited onto low-carbon steel 08kp in the presence of X-rays are presented. Relations of deposit rate, current efficiencies, element and phase compositions of CoNiFe coatings formed from sulfate baths with respect to cathode current densities (0.5-3A/dm2), electrolyte composition and irradiation were obtained. It is shown that, the CoNiFe coatings deposited by the electrochemical method involving exposure of the X-rays are characterized by more perfect morphology surfaces with less developed surface geometry than reference coatings. The effect of the X-ray irradiation on the electrodeposition of CoNiFe coatings promotes formatting of alloys with increased electropositive component and modified phase composition.

Salivary enzymes are injected into xylem by the glassy-winged sharpshooter, a vector of Xylella fastidiosa.

Science.gov (United States)

Backus, Elaine A; Andrews, Kim B; Shugart, Holly J; Carl Greve, L; Labavitch, John M; Alhaddad, Hasan

2012-07-01

A few phytophagous hemipteran species such as the glassy-winged sharpshooter, Homalodisca vitripennis, (Germar), subsist entirely on xylem fluid. Although poorly understood, aspects of the insect's salivary physiology may facilitate both xylem-feeding and transmission of plant pathogens. Xylella fastidiosa is a xylem-limited bacterium that causes Pierce's disease of grape and other scorch diseases in many important crops. X. fastidiosa colonizes the anterior foregut (precibarium and cibarium) of H. vitripennis and other xylem-feeding vectors. Bacteria form a dense biofilm anchored in part by an exopolysaccharide (EPS) matrix that is reported to have a β-1,4-glucan backbone. Recently published evidence supports the following, salivation-egestion hypothesis for the inoculation of X. fastidiosa during vector feeding. The insect secretes saliva into the plant and then rapidly takes up a mixture of saliva and plant constituents. During turbulent fluid movements in the precibarium, the bacteria may become mechanically and enzymatically dislodged; the mixture is then egested back out through the stylets into plant cells, possibly including xylem vessels. The present study found that proteins extracted from dissected H. vitripennis salivary glands contain several enzyme activities capable of hydrolyzing glycosidic linkages in polysaccharides such as those found in EPS and plant cell walls, based on current information about the structures of those polysaccharides. One of these enzymes, a β-1,4-endoglucanase (EGase) was enriched in the salivary gland protein extract by subjecting the extract to a few, simple purification steps. The EGase-enriched extract was then used to generate a polyclonal antiserum that was used for immunohistochemical imaging of enzymes in sharpshooter salivary sheaths in grape. Results showed that enzyme-containing gelling saliva is injected into xylem vessels during sharpshooter feeding, in one case being carried by the transpiration stream away

Branching habit and the allocation of reproductive resources in conifers.

Science.gov (United States)

Leslie, Andrew B

2012-09-01

Correlated relationships between branch thickness, branch density, and twig and leaf size have been used extensively to study the evolution of plant canopy architecture, but fewer studies have explored the impact of these relationships on the allocation of reproductive resources. This study quantifies pollen cone production in conifers, which have similar basic reproductive biology but vary dramatically in branching habit, in order to test how differences in branch diameter influence pollen cone size and the density with which they are deployed in the canopy. Measurements of canopy branch density, the number of cones per branch and cone size were used to estimate the amount of pollen cone tissues produced by 16 species in three major conifer clades. The number of pollen grains produced was also estimated using direct counts from individual pollen cones. The total amount of pollen cone tissues in the conifer canopy varied little among species and clades, although vegetative traits such as branch thickness, branch density and pollen cone size varied over several orders of magnitude. However, branching habit controls the way these tissues are deployed: taxa with small branches produce small pollen cones at a high density, while taxa with large branches produce large cones relatively sparsely. Conifers appear to invest similar amounts of energy in pollen production independent of branching habit. However, similar associations between branch thickness, branch density and pollen cone size are seen across conifers, including members of living and extinct groups not directly studied here. This suggests that reproductive features relating to pollen cone size are in large part a function of the evolution of vegetative morphology and branching habit.

Foliar and soil nutrient distribution in conifer forests of moist temperate areas of himalayan and hindukush region of pakistan: a multivariate approach

International Nuclear Information System (INIS)

Ahmad, K.; Khan, Z.I.; Ashfaq, A.

2014-01-01

Foliar nutrient concentration for the dominant conifer species (Pinus wallichiana, Abies pindrow and Cedrus deodara) of moist temperate areas of Himalayan and Hindukush region of Pakistan was evaluated. Soils samples and conifer needles were collected from forests at 41 sites in the study area. Six macro and seven micronutrients were analyzed for both soils and tissue. The mean nutrient levels and variability for each species was evaluated. The gradients in tissue nutrients were exposed by means of correspondence analysis (CA) and canonical correspondence (CCA), for each species. The first CA axis of Pinus wallichiana data was significantly correlated with soil N, P and K (p<0.05). The second CA axis was correlated with P, B and Ca, while the third was correlated with K and Mg (p<0.05). The first CA axis of Abies pindrow was not correlated with any soil nutrients, but the second axis showed correlation with soil Ca (p<0.05) and the third with S, Fe and N (p at the most 0.05). Cedrus deodara CA axes were not markedly correlated with soil nutrients. Canonical correspondence analysis (CCA) exposed the correlation structure between tissue nutrient and soil nutrient matrices with similar results thereby supporting the results of CA. (author)

Plasticity in variation of xylem and phloem cell characteristics of Norway spruce under different local conditions

Directory of Open Access Journals (Sweden)

Jozica eGricar

2015-09-01

Full Text Available There is limited information on intra-annual plasticity of secondary tissues of tree species growing under different environmental conditions. To increase the knowledge about the plasticity of secondary growth, which allows trees to adapt to specific local climatic regimes, we examined climate–radial growth relationships of Norway spruce (Picea abies (L. H. Karst. from three contrasting locations in the temperate climatic zone by analyzing tree-ring widths for the period 1932–2010, and cell characteristics in xylem and phloem increments formed in the years 2009–2011. Variation in the structure of xylem and phloem increments clearly shows that plasticity in seasonal dynamics of cambial cell production and cell differentiation exists on xylem and phloem sides. Anatomical characteristics of xylem and phloem cells are predominantly site-specific characteristics, because they varied among sites but were fairly uniform among years in trees from the same site. Xylem and phloem tissues formed in the first part of the growing season seemed to be more stable in structure, indicating their priority over latewood and late phloem for tree performance. Long-term climate and radial growth analyses revealed that growth was in general less dependent on precipitation than on temperature; however, growth sensitivity to local conditions differed among the sites. Only partial dependence of radial growth of spruce on climatic factors on the selected sites confirms its strategy to adapt the structure of wood and phloem increments to function optimally in local conditions.

The amino acid distribution in rachis xylem sap and phloem exudate of Vitis vinifera 'Cabernet Sauvignon' bunches.

Science.gov (United States)

Gourieroux, Aude M; Holzapfel, Bruno P; Scollary, Geoffrey R; McCully, Margaret E; Canny, Martin J; Rogiers, Suzy Y

2016-08-01

Amino acids are essential to grape berry and seed development and they are transferred to the reproductive structures through the phloem and xylem from various locations within the plant. The diurnal and seasonal dynamics of xylem and phloem amino acid composition in the leaf petiole and bunch rachis of field-grown Cabernet Sauvignon are described to better understand the critical periods for amino acid import into the berry. Xylem sap was extracted by the centrifugation of excised leaf petioles and rachises, while phloem exudate was collected by immersing these structures in an ethylenediaminetetraacetic acid (EDTA) buffer. Glutamine and glutamic acid were the predominant amino acids in the xylem sap of both grapevine rachises and petioles, while arginine and glycine were the principal amino acids of the phloem exudate. The amino acid concentrations within the xylem sap and phloem exudate derived from these structures were greatest during anthesis and fruit set, and a second peak occurred within the rachis phloem at the onset of ripening. The concentrations of the amino acids within the phloem and xylem sap of the rachis were highest just prior to or after midnight while the flow of sugar through the rachis phloem was greatest during the early afternoon. Sugar exudation rates from the rachis was greater than that of the petiole phloem between anthesis and berry maturity. In summary, amino acid and sugar delivery through the vasculature to grape berries fluctuates over the course of the day as well as through the season and is not necessarily related to levels near the source. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Uncoupling between soil and xylem water isotopic composition: how to discriminate mobile and tightly-bound water?

Science.gov (United States)

Martín Gómez, Paula; Aguilera, Mònica; Pemán, Jesús; Gil Pelegrín, Eustaquio; Ferrio, Juan Pedro

2014-05-01

As a general rule, no isotopic fractionation occurs during water uptake and water transport, thus, xylem water reflects source water. However, this correspondence does not always happen. Isotopic enrichment of xylem water has been found in several cases and has been either associated to 'stem processes' like cuticular evaporation 1 and xylem-phloem communication under water stress 2,3 or to 'soil processes' such as species-specific use of contrasting water sources retained at different water potential forces in soil. In this regard, it has been demonstrated that mobile and tightly-bound water may show different isotopic signature 4,5. However, standard cryogenic distillation does not allow to separate different water pools within soil samples. Here, we carried out a study in a mixed adult forest (Pinus sylvestris, Quercus subpyrenaica and Buxus sempervirens) growing in a relatively deep loamy soil in the Pre-Pyrenees. During one year, we sampled xylem from twigs and soil at different depths (10, 30 and 50 cm). We also sampled xylem from trunk and bigger branches to assess whether xylem water was enriched in the distal parts of the tree. We found average deviations in the isotopic signature from xylem to soil of 4o 2o and 2.4o in δ18O and 18.3o 7.3o and 8.9o in δ2H, for P.sylvestris, Q.subpyrenaica and B.sempervirens respectively. Xylem water was always enriched compared to soil. In contrast, we did not find clear differences in isotopic composition between xylem samples along the tree. Declining the hypothesis that 'stem processes' would cause these uncoupling between soil and xylem isotopic values, we tested the possibility to separate mobile and tightly-bound water by centrifugation. Even though we could separate two water fractions in soils close to saturation, we could not recover a mobile fraction in drier soils. In this regard, we welcome suggestions on alternatives to separate different soil fractions in order to find the correspondence between soil and

Trade-offs between xylem hydraulic properties, wood anatomy and yield in Populus.

Science.gov (United States)

Hajek, Peter; Leuschner, Christoph; Hertel, Dietrich; Delzon, Sylvain; Schuldt, Bernhard

2014-07-01

Trees face the dilemma that achieving high plant productivity is accompanied by a risk of drought-induced hydraulic failure due to a trade-off in the trees' vascular system between hydraulic efficiency and safety. By investigating the xylem anatomy of branches and coarse roots, and measuring branch axial hydraulic conductivity and vulnerability to cavitation in 4-year-old field-grown aspen plants of five demes (Populus tremula L. and Populus tremuloides Michx.) differing in growth rate, we tested the hypotheses that (i) demes differ in wood anatomical and hydraulic properties, (ii) hydraulic efficiency and safety are related to xylem anatomical traits, and (iii) aboveground productivity and hydraulic efficiency are negatively correlated to cavitation resistance. Significant deme differences existed in seven of the nine investigated branch-related anatomical and hydraulic traits but only in one of the four coarse-root-related anatomical traits; this likely is a consequence of high intra-plant variation in root morphology and the occurrence of a few 'high-conductivity roots'. Growth rate was positively related to branch hydraulic efficiency (xylem-specific conductivity) but not to cavitation resistance; this indicates that no marked trade-off exists between cavitation resistance and growth. Both branch hydraulic safety and hydraulic efficiency significantly depended on vessel size and were related to the genetic distance between the demes, while the xylem pressure causing 88% loss of hydraulic conductivity (P88 value) was more closely related to hydraulic efficiency than the commonly used P50 value. Deme-specific variation in the pit membrane structure may explain why vessel size was not directly linked to growth rate. We conclude that branch hydraulic efficiency is an important growth-influencing trait in aspen, while the assumed trade-off between productivity and hydraulic safety is weak. © The Author 2014. Published by Oxford University Press. All rights reserved

Circadian patterns of xylem sap properties and their covariation with plant hydraulic traits in hybrid aspen.

Science.gov (United States)

Meitern, Annika; Õunapuu-Pikas, Eele; Sellin, Arne

2017-06-01

Physiological processes taking place in plants are subject to diverse circadian patterns but some of them are poorly documented in natural conditions. The daily dynamics of physico-chemical properties of xylem sap and their covariation with tree hydraulic traits were investigated in hybrid aspen (Populus tremula L.×P. tremuloides Michx) in field conditions in order to clarify which environmental drivers govern the daily variation in these parameters. K + concentration ([K + ]), electrical conductivity (σ sap ), osmolality (Osm) and pH of the xylem sap, as well as branch hydraulic traits, were measured in the field over 24-h cycles. All studied xylem sap properties and hydraulic characteristics including whole-branch (K wb ), leaf blade (K lb ) and petiole hydraulic conductances (K P ) showed clear daily dynamics. Air temperature (T A ) and photosynthetic photon flux density (PPFD), but also water vapour pressure deficit (VPD) and relative humidity (RH), had significant impacts on K wb K lb , K P , [K + ] and σ sap . Osm varied only with light intensity, while K B varied depending on atmospheric evaporative demand expressed as T A , VPD or RH. Xylem sap pH depended inversely on soil water potential (Ψ S ) and during daylight also on VPD. Although soil water content was close to saturation during the study period, Ψ S influenced also [K + ] and σ sap . The present study presents evidence of coupling between circadian patterns of xylem sap properties and plant hydraulic conductance providing adequate water supply to foliage under environmental conditions characterised by diurnal variation. Copyright © 2017 Elsevier GmbH. All rights reserved.

Xylem monoterpenes of pines: distribution, variation, genetics, function

Science.gov (United States)

Richard Smith

2000-01-01

The monoterpenes of about 16,000 xylem resin samples of pine (Pinus) speciesand hybrids—largely from the western United States—were analyzed in this long-term study of the resistance of pines to attack by bark beetles (Coleoptera:Scolytidae), with special emphasis on resistance to the western pine beetle(Dendroctonus brevicomis). The samples were analyzed by gas liquid...

Molecular characterization of Fusarium oxysporum and fusarium commune isolates from a conifer nursery

Science.gov (United States)

Jane E. Stewart; Mee-Sook Kim; Robert L. James; R. Kasten Dumroese; Ned B. Klopfenstein

2006-01-01

Fusarium species can cause severe root disease and damping-off in conifer nurseries. Fusarium inoculum is commonly found in most container and bareroot nurseries on healthy and diseased seedlings, in nursery soils, and on conifer seeds. Isolates of Fusarium spp. can differ in virulence; however, virulence and...

Symplasmic, long-distance transport in xylem and cambial regions in branches of Acer pseudoplatanus (Aceraceae) and Populus tremula x P. tremuloides (Salicaceae).

Science.gov (United States)

Sokołowska, Katarzyna; Zagórska-Marek, Beata

2012-11-01

The picture of how long-distance transport proceeds in trees is still far from being complete. Beside the apoplasmic pathway, transport undoubtedly also takes place within the system of living cells in the secondary xylem and cambial region. Because detailed, thorough studies of the symplasmic routes in woody branches, using direct localization with fluorescent tracers, had not been done, here we focused on the main routes of long-distance symplasmic transport in xylem and cambial tissues and analyzed in detail tracer distribution in the rays on the extended cambial surface in branches of Acer pseudoplatanus and Populus tremula ×P. tremuloides. Fluorescent tracers were loaded into branches through the vascular system, then their distribution in xylem and cambial regions was analyzed. Tracer signal was present in the symplast of axial and radial xylem parenchyma cells and in both types of cambial cells. The living cells of xylem parenchyma and of the cambium were symplasmically interconnected via xylem rays. Tracer distribution in rays was uneven on the extended cambial surface; cambial regions with intensively or sparsely dyed rays alternated along the vertical axis of analyzed branches. Symplasmic, long-distance transport is present between the living cells of xylem and the cambial region in woody branches. The uneven distribution of fluorescent tracers in cambial rays along the stems is surprising and suggests the presence of an intrinsic pattern caused by an unknown mechanism.

Metabolomics of tomato xylem sap during bacterial wilt reveals Ralstonia solanacearum produces abundant putrescine, a metabolite that accelerates wilt disease.

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Lowe-Power, Tiffany M; Hendrich, Connor G; von Roepenack-Lahaye, Edda; Li, Bin; Wu, Dousheng; Mitra, Raka; Dalsing, Beth L; Ricca, Patrizia; Naidoo, Jacinth; Cook, David; Jancewicz, Amy; Masson, Patrick; Thomma, Bart; Lahaye, Thomas; Michael, Anthony J; Allen, Caitilyn

2018-04-01

Ralstonia solanacearum thrives in plant xylem vessels and causes bacterial wilt disease despite the low nutrient content of xylem sap. We found that R. solanacearum manipulates its host to increase nutrients in tomato xylem sap, enabling it to grow better in sap from infected plants than in sap from healthy plants. Untargeted GC/MS metabolomics identified 22 metabolites enriched in R. solanacearum-infected sap. Eight of these could serve as sole carbon or nitrogen sources for R. solanacearum. Putrescine, a polyamine that is not a sole carbon or nitrogen source for R. solanacearum, was enriched 76-fold to 37 µM in R. solanacearum-infected sap. R. solanacearum synthesized putrescine via a SpeC ornithine decarboxylase. A ΔspeC mutant required ≥ 15 µM exogenous putrescine to grow and could not grow alone in xylem even when plants were treated with putrescine. However, co-inoculation with wildtype rescued ΔspeC growth, indicating R. solanacearum produced and exported putrescine to xylem sap. Intriguingly, treating plants with putrescine before inoculation accelerated wilt symptom development and R. solanacearum growth and systemic spread. Xylem putrescine concentration was unchanged in putrescine-treated plants, so the exogenous putrescine likely accelerated disease indirectly by affecting host physiology. These results indicate that putrescine is a pathogen-produced virulence metabolite. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

The C-household of young broad-leaved and conifer tree species exposed to long-term carbon limitation by shading

Science.gov (United States)

Weber, Raphael; Hoch, Günter

2017-04-01

Non-structural carbohydrates (NSC, i.e. free sugars and starch) are regarded as freely available carbon (C) reserves in plants. They are often quantified to estimate a plant's C-balance, assuming that NSC are controlled by the net-balance between photo-assimilation and C-usage (respiration, growth and other sinks). Within a recent field experiment, we investigated the extent, to which C-reserves (NSC) can be formed in young trees against prevailing C-sink demands (growth) under C-limitation. A total of almost 1000 individuals of two-year-old tree saplings from 6 deciduous, broadleaved species and 4 evergreen conifer species were planted on a field side. Half of the trees per species were treated with long-term C-limitation by exposing them to continuous deep shade conditions (5% of natural PPFD) under a permanent shading tent. C gas-exchange, growth and NSC tissue concentrations were analyzed in shaded and unshaded saplings for two consecutive years. Three months after the beginning of the experiment, leaf photosynthesis acclimatized to the low light conditions, with leaves of shaded trees showing significantly higher SLA and lower light saturation and maximum photosynthesis. During the second season of the experiment, most species exhibited very strong reductions in NSC, but much less pronounced reductions in growth. In contrast, other species, with few exceptions, kept NSC concentrations similar to unshaded controls, while growth virtually stopped under deep shade. In conclusion, we found species-specific strategies in the trees' C-household after two years of C-limitation, that fall into two major carbon allocation strategies: 1) "C-spenders", which deplete C reserves in order to keep up significant growth, and 2) "C-savers", which reduce C sink activities to a minimum in order to store substantial amounts of C reserves. Overall, early-successional species tended to follow the first strategy, while late-successional species tended to save higher C reserve pools

Contrasting xylem vessel constraints on hydraulic conductivity between native and non-native woody understory species

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Maria S Smith

2013-11-01

Full Text Available We examined the hydraulic properties of 82 native and non-native woody species common to forests of Eastern North America, including several congeneric groups, representing a range of anatomical wood types. We observed smaller conduit diameters with greater frequency in non-native species, corresponding to lower calculated potential vulnerability to cavitation index. Non-native species exhibited higher vessel-grouping in metaxylem compared with native species, however, solitary vessels were more prevalent in secondary xylem. Higher frequency of solitary vessels in secondary xylem was related to a lower potential vulnerability index. We found no relationship between anatomical characteristics of xylem, origin of species and hydraulic conductivity, indicating that non-native species did not exhibit advantageous hydraulic efficiency over native species. Our results confer anatomical advantages for non-native species under the potential for cavitation due to freezing, perhaps permitting extended growing seasons.

Upward translocation of 14C-amino compounds in xylem and phloem of citrus trees (citrus unshiu marc.)

International Nuclear Information System (INIS)

Kato, Tadashi; Yamagata, Makoto; Tsukahara, Sadao

1985-01-01

Upward and lateral movements of 14 C-amino compounds in intact trees and excised shoots, and upward translocation of major amino compounds in intact shoots were examined in the early stage of new shoot development. The results were summarized as follows. 1. Uniformly 14 C-labelled arginine, asparagine, aspartic acid and proline were steadily taken up by roots of intact trees, translocated to old leaves and new shoots, and appeared in the fed compound and its metabolized products in these organs. 2. 14 C-arginine, asparagine and proline were translocated upward not only via the xylem but also via the phloem. Lateral movements, from the xylem to the pholoem and from the phloem to the xylem, also occurred. These compounds showed different patterns in their movements. 14 C-arginine and its metabolic products tended to accumulate in the xylem and translocate upward in the xylem. This was in contrast to 14 C-proline and its metabolic products, which tended to accumulate in the phloem and translocate upward in the phloem. These findings were supported by the results obtained in intact shoots. 3. The 14 C-amino compounds were metabolized to soluble and insoluble compounds during the translocation and in the new shoots. However, they differed significantly in the extent of metabolic conversion during translocation; proline was hardly metabolized, arginine and asparagine were moderately metabolized, and aspartic acid was almost completely metabolized. (author)

Zeaxanthin-independent energy quenching and alternative electron sinks cause a decoupling of the relationship between the photochemical reflectance index (PRI) and photosynthesis in an evergreen conifer during spring.

Science.gov (United States)

Fréchette, Emmanuelle; Wong, Christopher Y S; Junker, Laura Verena; Chang, Christine Yao-Yun; Ensminger, Ingo

2015-12-01

In evergreen conifers, the winter down-regulation of photosynthesis and its recovery during spring are the result of a reorganization of the chloroplast and adjustments of energy-quenching mechanisms. These phenological changes may remain undetected by remote sensing, as conifers retain green foliage during periods of photosynthetic down-regulation. The aim was to assess if the timing of the spring recovery of photosynthesis and energy-quenching characteristics are accurately monitored by the photochemical reflectance index (PRI) in the evergreen conifer Pinus strobus. The recovery of photosynthesis was studied using chlorophyll fluorescence, leaf gas exchange, leaf spectral reflectance, and photosynthetic pigment measurements. To assess if climate change might affect the recovery of photosynthesis, seedlings were exposed to cold spring conditions or warm spring conditions with elevated temperature. An early spring decoupling of the relationship between photosynthesis and PRI in both treatments was observed. This was caused by differences between the timing of the recovery of photosynthesis and the timing of carotenoid and chlorophyll pool size adjustments which are the main factors controlling PRI during spring. It was also demonstrated that zeaxanthin-independent NPQ mechanisms undetected by PRI further contributed to the early spring decoupling of the PRI-LUE relationship. An important mechanism undetected by PRI seems to involve increased electron transport around photosystem I, which was a significant energy sink during the entire spring transition, particularly in needles exposed to a combination of high light and cold temperatures. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Genes, enzymes and chemicals of terpenoid diversity in the constitutive and induced defence of conifers against insects and pathogens.

Science.gov (United States)

Keeling, Christopher I; Bohlmann, Jörg

2006-01-01

Insects select their hosts, but trees cannot select which herbivores will feed upon them. Thus, as long-lived stationary organisms, conifers must resist the onslaught of varying and multiple attackers over their lifetime. Arguably, the greatest threats to conifers are herbivorous insects and their associated pathogens. Insects such as bark beetles, stem- and wood-boring insects, shoot-feeding weevils, and foliage-feeding budworms and sawflies are among the most devastating pests of conifer forests. Conifer trees produce a great diversity of compounds, such as an enormous array of terpenoids and phenolics, that may impart resistance to a variety of herbivores and microorganisms. Insects have evolved to specialize in resistance to these chemicals -- choosing, feeding upon, and colonizing hosts they perceive to be best suited to reproduction. This review focuses on the plant-insect interactions mediated by conifer-produced terpenoids. To understand the role of terpenoids in conifer-insect interactions, we must understand how conifers produce the wide diversity of terpenoids, as well as understand how these specific compounds affect insect behaviour and physiology. This review examines what chemicals are produced, the genes and proteins involved in their biosynthesis, how they work, and how they are regulated. It also examines how insects and their associated pathogens interact with, elicit, and are affected by conifer-produced terpenoids.

Seasonal embolism and xylem vulnerability in deciduous and evergreen Mediterranean trees influenced by proximity to a carbon dioxide spring

Energy Technology Data Exchange (ETDEWEB)

Tognetti, R.; Raschi, A. [Consiglio Nazionale della Ricerche, Firenze (Italy); Longobucco, A. [Centro Studi per l`Informatica applicata all`Agricoltura, Firenze (Italy)

1999-04-01

The effect of proximity to natural CO{sub 2} springs on seasonal patterns of xylem embolism in various species of Quercus (oak), Fraxinus, Populus (poplar) and Arbutus was studied. Xylem embolism was evaluated in both artificially dehydrated branches and in hydrated apical branches collected at monthly intervals over a 20-month period. Species-dependent differences in xylem hydraulic properties in response to elevated CO{sub 2} were noted. Populus tremula was the most embolized, an Arbutus unedo was the least embolized among the species examined. The actual differences in xylem vulnerability between trees growing near the CO{sub 2} spring and those growing in control area were small, however, these differences combined with the interaction of seasonal stress events, may be of great importance in determining future community composition in Mediterranean forest ecosystems. Causes and ecological significance of such differences are discussed vis-a-vis elevated carbon dioxide concentration and other environmental factors. 48 refs., 2 tabs., 3 figs.

Hierarchical statistical modeling of xylem vulnerability to cavitation.

Science.gov (United States)

Ogle, Kiona; Barber, Jarrett J; Willson, Cynthia; Thompson, Brenda

2009-01-01

Cavitation of xylem elements diminishes the water transport capacity of plants, and quantifying xylem vulnerability to cavitation is important to understanding plant function. Current approaches to analyzing hydraulic conductivity (K) data to infer vulnerability to cavitation suffer from problems such as the use of potentially unrealistic vulnerability curves, difficulty interpreting parameters in these curves, a statistical framework that ignores sampling design, and an overly simplistic view of uncertainty. This study illustrates how two common curves (exponential-sigmoid and Weibull) can be reparameterized in terms of meaningful parameters: maximum conductivity (k(sat)), water potential (-P) at which percentage loss of conductivity (PLC) =X% (P(X)), and the slope of the PLC curve at P(X) (S(X)), a 'sensitivity' index. We provide a hierarchical Bayesian method for fitting the reparameterized curves to K(H) data. We illustrate the method using data for roots and stems of two populations of Juniperus scopulorum and test for differences in k(sat), P(X), and S(X) between different groups. Two important results emerge from this study. First, the Weibull model is preferred because it produces biologically realistic estimates of PLC near P = 0 MPa. Second, stochastic embolisms contribute an important source of uncertainty that should be included in such analyses.

Does water transport scale universally with tree size?

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F.C. Meinzer; B.J. Bond; J.M. Warren; D.R. Woodruff

2005-01-01

1. We employed standardized measurement techniques and protocols to describe the size dependence of whole-tree water use and cross-sectional area of conducting xylem (sapwood) among several species of angiosperms and conifers. 2. The results were not inconsistent with previously proposed 314-power scaling of water transport with estimated above-...

Indicators of cull in western Oregon conifers.

Science.gov (United States)

Paul E. Aho

1982-01-01

Descriptions and color photographs of important fungal sporophores (conks), other indicators of cull (wounds), and associated decays in western Oregon conifers are provided to aid timber markers, cruisers, and scalers in identifying them. Cull factors are given for the indicators by tree species.

Vestured pits: a diagnostic character in the secondary xylem of Myrtales

NARCIS (Netherlands)

Jansen, S.; Pletsers, A.; Rabaey, D.; Lens, F.

2008-01-01

Vestures are small projections from the secondary cell wall associated with tracheary elements of the secondary xylem. They are usually associated with bordered pits and characterize various angiosperm families, including important timber species such as Dipterocarpaceae and Eucalyptus trees. The

Predation and protection in the macroevolutionary history of conifer cones

Science.gov (United States)

Leslie, Andrew B.

2011-01-01

Conifers are an excellent group in which to explore how changing ecological interactions may have influenced the allocation of reproductive tissues in seed plants over long time scales, because of their extensive fossil record and their important role in terrestrial ecosystems since the Palaeozoic. Measurements of individual conifer pollen-producing and seed-producing cones from the Pennsylvanian to the Recent show that the relative amount of tissue invested in pollen cones has remained constant through time, while seed cones show a sharp increase in proportional tissue investment in the Jurassic that has continued to intensify to the present day. Since seed size in conifers has remained similar through time, this increase reflects greater investment in protective cone tissues such as robust, tightly packed scales. This shift in morphology and tissue allocation is broadly concurrent with the appearance of new vertebrate groups capable of browsing in tree canopies, as well as a diversification of insect-feeding strategies, suggesting that an important change in plant–animal interactions occurred over the Mesozoic that favoured an increase in seed cone protective tissues. PMID:21345864

The hydraulic architecture of conifers

Science.gov (United States)

Uwe G Hacke; Barbara Lachenbruch; Jarmila Pittermann; Stefan Mayr; Jean-Christophe Domec; Paul J. Schulte

2015-01-01

Conifers survive in diverse and sometimes extreme environments (Fig. 2.1a–f). Piñon-juniper communities are found in semi-arid environments, receiving ca. 400 mm of yearly precipitation (Linton et al. 1998), which is less than half the average precipitations received by other coniferous tree species worldwide. Picea mariana and Larix laricina grow in boreal peatlands...

Understory plant diversity in riparian alder-conifer stands after logging in southeast Alaska.

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Robert L. Deal

1997-01-01

Stand structure, tree height growth, and understory plant diversity were assessed in five mixed alder-conifer stands after logging in southeast Alaska. Tree species composition ranged from 7- to 91-percent alder, and basal area ranged from 30 to 55 m2/ha. The alder exhibited rapid early height growth, but recent growth has slowed considerably. Some conifers have...

Chemical and anatomical changes in Liquidambar styraciflua L. xylem after long term exposure to elevated CO2

International Nuclear Information System (INIS)

Kim, Keonhee; Labbé, Nicole; Warren, Jeffrey M.; Elder, Thomas; Rials, Timothy G.

2015-01-01

The anatomical and chemical characteristics of sweetgum were studied after 11 years of elevated CO 2 (544 ppm, ambient at 391 ppm) exposure. Anatomically, branch xylem cells were larger for elevated CO 2 trees, and the cell wall thickness was thinner. Chemically, elevated CO 2 exposure did not impact the structural components of the stem wood, but non-structural components were significantly affected. Principal component analysis (PCA) was employed to detect differences between the CO 2 treatments by considering numerous structural and chemical variables, as well as tree size, and data from previously published sources (i.e., root biomass, production and turnover). The PCA results indicated a clear separation between trees exposed to ambient and elevated CO 2 conditions. Correlation loadings plots of the PCA revealed that stem structural components, ash, Ca, Mg, total phenolics, root biomass, production and turnover were the major responses that contribute to the separation between the elevated and ambient CO 2 treated trees. - Highlights: • First study of wood properties after 11 years of higher level of CO 2 treatment. • Elevated CO 2 exposure does not impact structural components of wood. • Total phenolics content and some inorganics were significantly affected. • Branch xylem cells were larger under elevated CO 2 . • Cell wall thickness was thinner under elevated CO 2 . - Elevated CO 2 in atmosphere did not impact the structural components yet altered some of non-structural components and anatomical properties after 11 years of exposure on sweetgum

Are phloem-derived amino acids the origin of the elevated malate concentration in the xylem sap following mineral N starvation in soybean?

Science.gov (United States)

Vitor, Simone C; do Amarante, Luciano; Sodek, Ladaslav

2018-05-16

A substantial increase in malate in the xylem sap of soybean subjected to mineral N starvation originates mainly from aspartate, a prominent amino acid of the phloem. A substantial increase in xylem malate was found when non-nodulated soybean plants were transferred to a N-free medium. Nodulated plants growing in the absence of mineral N and, therefore, dependent on symbiotic N 2 fixation also contained elevated concentrations of malate in the xylem sap. When either nitrate or ammonium was supplied, malate concentrations in the xylem sap were low, both for nodulated and non-nodulated plants. Evidence was obtained that the elevated malate concentration of the xylem was derived from amino acids supplied by the phloem. Aspartate was a prominent component of the phloem sap amino acids and, therefore, a potential source of malate. Supplying the roots of intact plants with 13 C-aspartate revealed that malate of the xylem sap was readily labelled under N starvation. A hypothetical scheme is proposed whereby aspartate supplied by the phloem is metabolised in the roots and the products of this metabolism cycled back to the shoot. Under N starvation, aspartate metabolism is diverted from asparagine synthesis to supply N for the synthesis of other amino acids via transaminase activity. The by-product of aspartate transaminase activity, oxaloacetate, is transformed to malate and its export accounts for much of the elevated concentration of malate found in the xylem sap. This mechanism represents a new additional role for malate during mineral N starvation of soybean, beyond that of charge balance.

Quantum Yields in Mixed-Conifer Forests and Ponderosa Pine Plantations

Science.gov (United States)

Wei, L.; Marshall, J. D.; Zhang, J.

2008-12-01

Most process-based physiological models require canopy quantum yield of photosynthesis as a starting point to simulate carbon sequestration and subsequently gross primary production (GPP). The quantum yield is a measure of photosynthetic efficiency expressed in moles of CO2 assimilated per mole of photons absorbed; the process is influenced by environmental factors. In the summer 2008, we measured quantum yields on both sun and shade leaves for four conifer species at five sites within Mica Creek Experimental Watershed (MCEW) in northern Idaho and one conifer species at three sites in northern California. The MCEW forest is typical of mixed conifer stands dominated by grand fir (Abies grandis (Douglas ex D. Don) Lindl.). In northern California, the three sites with contrasting site qualities are ponderosa pine (Pinus ponderosa C. Lawson var. ponderosa) plantations that were experimentally treated with vegetation control, fertilization, and a combination of both. We found that quantum yields in MCEW ranged from ~0.045 to ~0.075 mol CO2 per mol incident photon. However, there were no significant differences between canopy positions, or among sites or tree species. In northern California, the mean value of quantum yield of three sites was 0.051 mol CO2/mol incident photon. No significant difference in quantum yield was found between canopy positions, or among treatments or sites. The results suggest that these conifer species maintain relatively consistent quantum yield in both MCEW and northern California. This consistency simplifies the use of a process-based model to accurately predict forest productivity in these areas.

Interplay of growth rate and xylem plasticity for optimal coordination of carbon and hydraulic economies in Fraxinus ornus trees.

Science.gov (United States)

Petit, Giai; Savi, Tadeja; Consolini, Martina; Anfodillo, Tommaso; Nardini, Andrea

2016-11-01

Efficient leaf water supply is fundamental for assimilation processes and tree growth. Renovating the architecture of the xylem transport system requires an increasing carbon investment while growing taller, and any deficiency of carbon availability may result in increasing hydraulic constraints to water flow. Therefore, plants need to coordinate carbon assimilation and biomass allocation to guarantee an efficient and safe long-distance transport system. We tested the hypothesis that reduced branch elongation rates together with carbon-saving adjustments of xylem anatomy hydraulically compensate for the reduction in biomass allocation to xylem. We measured leaf biomass, hydraulic and anatomical properties of wood segments along the main axis of branches in 10 slow growing (SG) and 10 fast growing (FG) Fraxinus ornus L. trees. Branches of SG trees had five times slower branch elongation rate (7 vs 35 cm year -1 ), and produced a higher leaf biomass (P trees in terms of leaf-specific conductivity (P > 0.05) and xylem safety (Ψ 50 ≈ -3.2 MPa). Slower elongation rate coupled with thinner annual rings and larger vessels allows the reduction of carbon costs associated with growth, while maintaining similar leaf-specific conductivity and xylem safety. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Transport and use of CO2 in the xylem sap of Populus deltoides

International Nuclear Information System (INIS)

Stringer, J.W.; Kimmerer, T.W.

1990-01-01

Results of recent experiments indicate an internal cycling of respiratory CO 2 in woody plants. The CO 2 concentration of xylem sap expressed from the twigs of field grown Populus deltoides ranged from .14 to .50 mM. The pH of the xylem sap was 5.7 to 6.7, providing a significant bicarbonate concentration in many samples. Total dissolved inorganic carbon (DIC = CO 2 + H 2 CO 3 + HCO 3 - ) was 0.5 mM to 1.3 mM. Results from the analysis of xylem sap of 10 other species of woody plants were similar. To determine the fate of DIC delivered to the leaves of Populus deltoides, excised leaves were fed 1mM NaHCO 3 (2 μCi NaH 14 CO 3 ml -1 ). Less than 0.4% of the label escaped from the leaves, and ≥93% was fixed. Of the carbon fixed 56% of the 14 C was found in the petiole and midrib, and 14% was in the major veins, with the remaining 30% in the minor veins and lamina. Shading of the peptiole and midrib of leaves decreased the amount of fixed carbon in these tissues to 38% and increased the amount in the lamina to 55%

Spatial and temporal patterns of xylem sap pH derived from stems and twigs of Populus deltoides L.

Science.gov (United States)

Doug Aubrey; Justin Boyles; Laura Krysinsky; Robert Teskey

2011-01-01

Xylem sap pH (pHX) is critical in determining the quantity of inorganic carbon dissolved in xylem solution from gaseous [CO2] measurements. Studies of internal carbon transport have generally assumed that pHX derived from stems and twigs is similar and that pHX remains constant through time; however, no empirical studies have investigated these assumptions. If any of...

Moving beyond the cambium necrosis hypothesis of post-fire tree mortality: cavitation and deformation of xylem in forest fires

Science.gov (United States)

S.T. Michaletz; E.A. Johnson; M.T. Tyree

2012-01-01

It is widely assumed that post-fire tree mortality results from necrosis of phloem and vascular cambium in stems, despite strong evidence that reduced xylem conductivity also plays an important role. In this study, experiments with Populus balsamifera were used to demonstrate two mechanisms by which heat reduces the hydraulic conductivity of xylem:...

Tree mortality in drought-stressed mixed-conifer and ponderosa pine forests, Arizona, USA

Science.gov (United States)

Joseph L. Ganey; Scott C. Vojta

2011-01-01

We monitored tree mortality in northern Arizona (USA) mixed-conifer and ponderosa pine (Pinus ponderosa Dougl. ex Laws) forests from 1997 to 2007, a period of severe drought in this area. Mortality was pervasive, occurring on 100 and 98% of 53 mixed-conifer and 60 ponderosa pine plots (1-ha each), respectively. Most mortality was attributable to a suite of forest...

Infection processes of xylem-colonizing pathogenic bacteria: possible explanations for the scarcity of qualitative disease resistance genes against them in crops.

Science.gov (United States)

Bae, Chungyun; Han, Sang Wook; Song, Yu-Rim; Kim, Bo-Young; Lee, Hyung-Jin; Lee, Je-Min; Yeam, Inhwa; Heu, Sunggi; Oh, Chang-Sik

2015-07-01

Disease resistance against xylem-colonizing pathogenic bacteria in crops. Plant pathogenic bacteria cause destructive diseases in many commercially important crops. Among these bacteria, eight pathogens, Ralstonia solanacearum, Xanthomonas oryzae pv. oryzae, X. campestris pv. campestris, Erwinia amylovora, Pantoea stewartii subsp. stewartii, Clavibacter michiganensis subsp. michiganensis, Pseudomonas syringae pv. actinidiae, and Xylella fastidiosa, infect their host plants through different infection sites and paths and eventually colonize the xylem tissues of their host plants, resulting in wilting symptoms by blocking water flow or necrosis of xylem tissues. Noticeably, only a relatively small number of resistant cultivars in major crops against these vascular bacterial pathogens except X. oryzae pv. oryzae have been found or generated so far, although these pathogens threaten productivity of major crops. In this review, we summarize the lifestyles of major xylem-colonizing bacterial pathogens and then discuss the progress of current research on disease resistance controlled by qualitative disease resistance genes or quantitative trait loci against them. Finally, we propose infection processes of xylem-colonizing bacterial pathogens as one of possible reasons for why so few qualitative disease resistance genes against these pathogens have been developed or identified so far in crops.

Metabolite changes in conifer buds and needles during forced bud break in Norway spruce (Picea abies and European silver fir (Abies alba

Directory of Open Access Journals (Sweden)

Priyanka eDhuli

2014-12-01

Full Text Available Environmental changes such as early spring and warm spells induce bud burst and photosynthetic processes in cold-acclimated coniferous trees and consequently, cellular metabolism in overwintering needles and buds. The purpose of the study was to examine metabolism in conifers under forced deacclimation (artificially induced spring by exposing shoots of Picea abies (boreal species and Abies alba (temperate species to a greenhouse environment (22°C, 16/8 h D/N cycle over a nine week period. Each week, we scored bud opening and collected samples for GC/MS–based metabolite profiling. We detected a total of 169 assigned metabolites and 80 identified metabolites, comprising compounds such as mono- and disaccharides, Krebs cycle acids, amino acids, polyols, phenolics and phosphorylated structures. Untargeted multivariate statistical analysis based on PCA and cluster analysis segregated samples by species, tissue type, and stage of tissue deacclimations. Similar patterns of metabolic regulation in both species were observed in buds (amino acids, Krebs cycle acids and needles (hexoses, pentoses, and Krebs cycle acids. Based on correlation of bud opening score with compound levels, distinct metabolites could be associated with bud and shoot development, including amino acids, sugars and acids with known osmolyte function, and secondary metabolites. This study has shed light on how elevated temperature affects metabolism in buds and needles of conifer species during the deacclimation phase, and contributes to the discussion about how phenological characters in conifers may respond to future global warming.

Plastic bimodal xylogenesis in conifers from continental Mediterranean climates.

Science.gov (United States)

Camarero, Jesús Julio; Olano, José Miguel; Parras, Alfonso

2010-01-01

*Seasonal radial-increment and xylogenesis data can help to elucidate how climate modulates wood formation in conifers. Few xylogenesis studies have assessed how plastic xylogenesis is in sympatric conifer species from continental Mediterranean areas, where low winter temperatures and summer drought constrain growth. *Here, we analysed intra-annual patterns of secondary growth in sympatric conifer species (Juniperus thurifera, Pinus halepensis and Pinus sylvestris). Two field sites (xeric and mesic) were evaluated using dendrometers, microcores and climatic data. *A bimodal pattern of xylogenesis characterized by spring and autumn precipitation and subsequent cambial reactivation was detected in J. thurifera at both study sites and in P. halepensis at the xeric site, but was absent in P. sylvestris where growth was largely controlled by day length. In the xeric site J. thurifera exhibited an increased response to water availability in autumn relative to P. halepensis and summer cambial suppression was more marked in J. thurifera than in P. halepensis. *Juniperus thurifera exhibited increased plasticity in its xylogenesis pattern compared with sympatric pines, enabling this species to occupy sites with more variable climatic conditions. The plastic xylogenesis patterns of junipers in drought-stressed areas may also provide them with a competitive advantage against co-occurring pines.

Xylem vulnerability to cavitation can be accurately characterised in species with long vessels using a centrifuge method.

Science.gov (United States)

Tobin, M F; Pratt, R B; Jacobsen, A L; De Guzman, M E

2013-05-01

Vulnerability to cavitation curves describe the decrease in xylem hydraulic conductivity as xylem pressure declines. Several techniques for constructing vulnerability curves use centrifugal force to induce negative xylem pressure in stem or root segments. Centrifuge vulnerability curves constructed for long-vesselled species have been hypothesised to overestimate xylem vulnerability to cavitation due to increased vulnerability of vessels cut open at stem ends that extend to the middle or entirely through segments. We tested two key predictions of this hypothesis: (i) centrifugation induces greater embolism than dehydration in long-vesselled species, and (ii) the proportion of open vessels changes centrifuge vulnerability curves. Centrifuge and dehydration vulnerability curves were compared for a long- and short-vesselled species. The effect of open vessels was tested in four species by comparing centrifuge vulnerability curves for stems of two lengths. Centrifuge and dehydration vulnerability curves agreed well for the long- and short-vesselled species. Centrifuge vulnerability curves constructed using two stem lengths were similar. Also, the distribution of embolism along the length of centrifuged stems matched the theoretical pressure profile induced by centrifugation. We conclude that vulnerability to cavitation can be accurately characterised with vulnerability curves constructed using a centrifuge technique, even in long-vesselled species. © 2012 German Botanical Society and The Royal Botanical Society of the Netherlands.

Anisotropic nanolaminated CoNiFe cores integrated into microinductors for high-frequency dc–dc power conversion

International Nuclear Information System (INIS)

Kim, Jooncheol; Kim, Minsoo; Herrault, Florian; Kim, Jung-Kwun; Allen, Mark G

2015-01-01

This paper presents a rectangular, anisotropic nanolaminated CoNiFe core that possesses a magnetically hard axis in the long geometric axis direction. Previously, we have developed nanolaminated cores comprising tens to hundreds of layers of 300–1000 nm thick metallic alloys (i.e. Ni 80 Fe 20 or Co 44 Ni 37 Fe 19 ) based on sequential electrodeposition, demonstrating suppressed eddy-current losses at MHz frequencies. In this work, magnetic anisotropy was induced to the nanolaminated CoNiFe cores by applying an external magnetic field (50–100 mT) during CoNiFe film electrodeposition. The fabricated cores comprised tens to hundreds of layers of 500–1000 nm thick CoNiFe laminations that have the hard-axis magnetic property. Packaged in a 22-turn solenoid test inductor, the anisotropic core showed 10% increased effective permeability and 25% reduced core power losses at MHz operation frequency, compared to an isotropic core of the identical geometry. Operating the anisotropic nanolaminated CoNiFe core in a step-down dc–dc converter (15 V input to 5 V output) demonstrated 81% converter efficiency at a switching frequency of 1.1 MHz and output power of 6.5 W. A solenoid microinductor with microfabricated windings integrated with the anisotropic nanolaminated CoNiFe core was fabricated, demonstrating a constant inductance of 600 nH up to 10 MHz and peak quality factor exceeding 20 at 4 MHz. The performance of the microinductor with the anisotropic nanolaminated CoNiFe core is compared with other previously reported microinductors. (fast track communication)

High-frequency permeability of electroplated CoNiFe and CoNiFe-C alloys

International Nuclear Information System (INIS)

Rhen, Fernando M.F.; McCloskey, Paul; O'Donnell, Terence; Roy, Saibal

2008-01-01

We have investigated CoNiFe and CoNiFe-C electrodeposited by pulse reverse plating (PRP) and direct current (DC) techniques. CoNiFe(PRP) films with composition Co 59.4 Fe 27.7 Ni 12.8 show coercivity of 95 A m -1 (1.2 Oe) and magnetization saturation flux (μ 0 M s ) of 1.8 T. Resistivity of CoNiFe (PRP) is about 24 μΩ cm and permeability remains almost constant μ r ' ∼475 up to 30 MHz with a quality factor (Q) larger than 10. Additionally, the permeability spectra analysis shows that CoNiFe exhibits a classical eddy current loss at zero bias field and ferromagnetic resonance (FMR) when biased with 0.05 T. Furthermore, a crossover between eddy current and FMR loss is observed for CoNiFe-PRP when baised with 0.05 T. DC and PRP plated CoNiFe-C, which have resistivity and permeability of 85, 38 μΩ cm, μ r '=165 and 35 with Q>10 up to 320 MHz, respectively, showed only ferromagnetic resonance losses. The ferromagnetic resonance peaks in CoNiFe and CoNiFe-C are broad and resembles a Gaussian distribution of FMR frequencies. The incorporation of C to CoNiFe reduces eddy current loss, but also reduces the FMR frequency

The study of Cr(III) complexation in the xylem sap using ion exchange and radiotracer

International Nuclear Information System (INIS)

Juneja, Shikha; Prakash, Satya

2003-01-01

Radiotracer was employed to carry out ion exchange experiments to study the chromium speciation in the in vitro samples of xylem sap of maize stem of 60 days old plants. Cr(III) radiolabelled with its radioactive isotope ( 51 Cr) was mixed with both the ion exchange fraction of the sap which represented the carboxylic acids, as well as the whole sap and was analysed for complexation after 10 and 30 days at 25 degC. Prior to this, the ion exchange elution chromatography of Cr(III), and the Cr(III) complexes with oxalic and citric acid were used to compare the complexes being formed in the in vitro studies. The in vitro Cr(III) complexation results indicated that Cr(III) was vitally present as anionic species. The elution curve trend was similar to that of citric acid complexation. Citric acid was also found to be the major complexing acid in the xylem sap as determined by HPLC. The results indicate the transportation of Cr(III) as a citrate complex in the xylem sap of maize plants. (author)

Data on xylem sap proteins from Mn- and Fe-deficient tomato plants obtained using shotgun proteomics.

Science.gov (United States)

Ceballos-Laita, Laura; Gutierrez-Carbonell, Elain; Takahashi, Daisuke; Abadía, Anunciación; Uemura, Matsuo; Abadía, Javier; López-Millán, Ana Flor

2018-04-01

This article contains consolidated proteomic data obtained from xylem sap collected from tomato plants grown in Fe- and Mn-sufficient control, as well as Fe-deficient and Mn-deficient conditions. Data presented here cover proteins identified and quantified by shotgun proteomics and Progenesis LC-MS analyses: proteins identified with at least two peptides and showing changes statistically significant (ANOVA; p ≤ 0.05) and above a biologically relevant selected threshold (fold ≥ 2) between treatments are listed. The comparison between Fe-deficient, Mn-deficient and control xylem sap samples using a multivariate statistical data analysis (Principal Component Analysis, PCA) is also included. Data included in this article are discussed in depth in the research article entitled "Effects of Fe and Mn deficiencies on the protein profiles of tomato ( Solanum lycopersicum) xylem sap as revealed by shotgun analyses" [1]. This dataset is made available to support the cited study as well to extend analyses at a later stage.

Genotypic difference in salinity tolerance in quinoa is determined by differential control of xylem Na+ loading and stomatal density

DEFF Research Database (Denmark)

Shabala, Sergey; Hariadi, Yuda; Jacobsen, Sven-Erik

2013-01-01

old seedlings. Six weeks after the treatment commenced, leaf sap Na and K content and osmolality, stomatal density, chlorophyll fluorescence characteristics, and xylem sap Na and K composition were measured. Responses to salinity differed greatly among the varieties. All cultivars had substantially...... increased K+ concentrations in the leaf sap, but the most tolerant cultivars had lower xylem Na+ content at the time of sampling. Most tolerant cultivars had lowest leaf sap osmolality. All varieties reduced stomata density when grown under saline conditions. All varieties clustered into two groups...... to the xylem, and reduced stomata density are important physiological traits contributing to genotypic differences in salinity tolerance in quinoa, a halophyte species from Chenopodium family....

Red Alder-Conifer Stands in Alaska: An Example of Mixed Species Management to Enhance Structural and Biological Complexity

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Robert L. Deal

2017-04-01

Full Text Available There is worldwide interest in managing forests to improve biodiversity, enhance ecosystem services and assure long-term sustainability of forest resources. An increasingly important goal of forest management is to increase stand diversity and improve wildlife and aquatic habitat. Well-planned silvicultural systems containing a mixture of broadleaf-conifer species have potential to enhance stand diversity and provide other ecosystem services earlier than typical even-aged conifer plantations. Here, we use the example of mixed Sitka spruce/western hemlock and red alder in young, managed stands in southeast Alaska to achieve these goals. We briefly describe the silvics of Sitka spruce, western hemlock and red alder plantations as pure conifer stands or pure broadleaf stands. Then, we synthesize studies of mixed red alder-Sitka spruce/western hemlock stands in southeast Alaska and present their potential for improving stand structural complexity, biodiversity and other ecosystem services over pure conifer forests. Finally, we discuss some of the opportunities and potential tradeoffs for managing mixed broadleaf-conifer stands for providing a number of natural resources and the influence of these broadleaf-conifer forests on ecosystem linkages and processes.

Cell Wall Amine Oxidases: New Players in Root Xylem Differentiation under Stress Conditions

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Sandip A. Ghuge

2015-07-01

Full Text Available Polyamines (PAs are aliphatic polycations present in all living organisms. A growing body of evidence reveals their involvement as regulators in a variety of physiological and pathological events. They are oxidatively deaminated by amine oxidases (AOs, including copper amine oxidases (CuAOs and flavin adenine dinucleotide (FAD-dependent polyamine oxidases (PAOs. The biologically-active hydrogen peroxide (H2O2 is a shared compound in all of the AO-catalyzed reactions, and it has been reported to play important roles in PA-mediated developmental and stress-induced processes. In particular, the AO-driven H2O2 biosynthesis in the cell wall is well known to be involved in plant wound healing and pathogen attack responses by both triggering peroxidase-mediated wall-stiffening events and signaling modulation of defense gene expression. Extensive investigation by a variety of methodological approaches revealed high levels of expression of cell wall-localized AOs in root xylem tissues and vascular parenchyma of different plant species. Here, the recent progresses in understanding the role of cell wall-localized AOs as mediators of root xylem differentiation during development and/or under stress conditions are reviewed. A number of experimental pieces of evidence supports the involvement of apoplastic H2O2 derived from PA oxidation in xylem tissue maturation under stress-simulated conditions.

Three centuries of managing introduced conifers in South Africa: benefits, impacts, changing perceptions and conflict resolution

CSIR Research Space (South Africa)

Van Wilgen, BW

2012-05-01

Full Text Available have brought many benefits but have also caused unintended problems. The management of alien conifers has evolved in response to emerging problems such as excessive water use by plantations of conifers, changing values and markets, and the realities...

Investigating differences in the root to shoot transfer and xylem sap solubility of organic compounds between zucchini, squash and soybean using a pressure chamber method.

Science.gov (United States)

Garvin, Naho; Doucette, William J; White, Jason C

2015-07-01

A pressure chamber method was used to examine differences in the root to shoot transfer and xylem sap solubility of caffeine (log Kow=-0.07), triclocarban (log Kow=3.5-4.2) and endosulfan (log Kow=3.8-4.8) for zucchini (cucurbita pepo ssp pepo), squash (cucurbita pepo ssp ovifera), and soybean (glycine max L.). Transpiration stream concentration factors (TSCF) for caffeine (TSCF=0.8) were statistically equivalent for all plant species. However, for the more hydrophobic endosulfan and triclocarban, the TSCF values for zucchini (TSCF=0.6 and 0.4, respectively) were 3 and 10 times greater than the soybean and squash (TSCF=0.2 and 0.05, respectively). The difference in TSCF values was examined by comparing the measured solubilities of caffeine, endosulfan and triclocarban in deionized water to those in soybean and zucchini xylem saps using a modified shake flask method. The measured solubility of organic contaminants in xylem sap has not previously been reported. Caffeine solubilities in the xylem saps of soybean and zucchini were statistically equal to deionized water (21500mgL(-1)) while endosulfan and triclocarban solubilities in the zucchini xylem sap were significantly greater (0.43 and 0.21mgL(-1), respectively) than that of the soybean xylem sap (0.31 and 0.11mgL(-1), respectively) and deionized water (0.34 and 0.11mgL(-1), respectively). This suggests that the enhanced root to shoot transfer of hydrophobic organics reported for zucchini is partly due to increased solubility in the xylem sap. Further xylem sap characterization is needed to determine the mechanism of solubility enhancement. Copyright © 2014 Elsevier Ltd. All rights reserved.

Long-term persistence and fire resilience of oak shrubfields in dry conifer forests of northern New Mexico

Science.gov (United States)

Guiterman, Christopher H.; Margolis, Ellis; Allen, Craig D.; Falk, Donald A.; Swetnam, Thomas W.

2017-01-01

Extensive high-severity fires are creating large shrubfields in many dry conifer forests of the interior western USA, raising concerns about forest-to-shrub conversion. This study evaluates the role of disturbance in shrubfield formation, maintenance and succession in the Jemez Mountains, New Mexico. We compared the environmental conditions of extant Gambel oak (Quercus gambelii) shrubfields with adjoining dry conifer forests and used dendroecological methods to determine the multi-century fire history and successional dynamics of five of the largest shrubfields (76–340 ha). Across the study area, 349 shrubfields (5–368 ha) occur in similar topographic and climate settings as dry conifer forests. This suggests disturbance, rather than other biophysical factors, may explain their origins and persistence. Gambel oak ages and tree-ring fire scars in our sampled shrubfields indicate they historically (1664–1899) burned concurrently with adjoining conifer forests and have persisted for over 115 years in the absence of fire. Aerial imagery from 1935 confirmed almost no change in sampled shrubfield patch sizes or boundaries over the twentieth century. The largest shrubfield we identified is less than 4% the size of the largest conifer-depleted and substantially shrub-dominated area recently formed in the Jemez following extensive high-severity wildfires, indicating considerable departure from historical patterns and processes. Projected hotter droughts and increasingly large high-severity fires could trigger more forest-to-shrub transitions and maintain existing shrubfields, inhibiting conifer forest recovery. Restoration of surface fire regimes and associated historical forest structures likely could reduce the rate and patch size of dry conifer forests being converted to shrubfields.

Xylem Resin in the Resistance of the Pinaceae to Bark Beetles

Science.gov (United States)

Richard H. Smith

1972-01-01

Xylem resin of Pinaceae is closely linked with their resistance and suseptibility to tree-killing bark beetles. This review of the literature on attacking adults suggests that all three resistance mechanisms proposed by Painter -- preference, antibiosis, and tolerance -- are active in this relationship: preference by attraction, repellency, and synergism; antibiosis...

Influence of Ti addition and sintering method on microstructure and mechanical behavior of a medium-entropy Al0.6CoNiFe alloy

International Nuclear Information System (INIS)

Fu, Zhiqiang; Chen, Weiping; Chen, Zhen; Wen, Haiming; Lavernia, Enrique J.

2014-01-01

The influence of Ti addition and sintering method on the microstructure and mechanical behavior of a medium-entropy alloy, Al 0.6 CoNiFe alloy, was studied in detail. Alloying behavior, microstructure, phase evolution and mechanical properties of Al 0.6 CoNiFe and Ti 0.4 Al 0.6 CoNiFe alloys were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), as well as by mechanical testing. During the mechanical alloying (MA) process, a supersaturated solid solution consisting of both BCC and FCC phases was formed in the Al 0.6 CoNiFe alloy. With Ti addition, the Ti 0.4 Al 0.6 CoNiFe alloy exhibited a supersaturated solid solution with a single FCC phase. Following hot pressing (HP), the HP sintered (HP’ed) Al 0.6 CoNiFe bulk alloy was composed of a major BCC phase and a minor FCC phase. The HP’ed Ti 0.4 Al 0.6 CoNiFe alloy exhibited a FCC phase, two BCC phases and a trace unidentified phase. Nanoscale twins were present in the HP’ed Ti 0.4 Al 0.6 CoNiFe alloy, where deformation twins were observed in the FCC phase. Our results suggest that the addition of Ti facilitated the formation of nanoscale twins. The compressive strength and Vickers hardness of HP’ed Ti 0.4 Al 0.6 CoNiFe alloy were slightly lower than the corresponding values of the HP’ed Al 0.6 CoNiFe alloy. In contrast with HP’ed Al 0.6 CoNiFe alloy, spark plasma sintered (SPS’ed) Al 0.6 CoNiFe alloy exhibited a major FCC phase and a minor BCC phase. Moreover, the SPS’ed Al 0.6 CoNiFe alloy exhibited a lower compressive strength and Vickers hardness, but singificantly higher plasticity, as compared to those of the HP’ed counterpart material

Quantitative Evaluation of Hybrid Aspen Xylem and Immunolabeling Patterns Using Image Analysis and Multivariate Statistics

Directory of Open Access Journals (Sweden)

David Sandquist

2015-06-01

Full Text Available A new method is presented for quantitative evaluation of hybrid aspen genotype xylem morphology and immunolabeling micro-distribution. This method can be used as an aid in assessing differences in genotypes from classic tree breeding studies, as well as genetically engineered plants. The method is based on image analysis, multivariate statistical evaluation of light, and immunofluorescence microscopy images of wood xylem cross sections. The selected immunolabeling antibodies targeted five different epitopes present in aspen xylem cell walls. Twelve down-regulated hybrid aspen genotypes were included in the method development. The 12 knock-down genotypes were selected based on pre-screening by pyrolysis-IR of global chemical content. The multivariate statistical evaluations successfully identified comparative trends for modifications in the down-regulated genotypes compared to the unmodified control, even when no definitive conclusions could be drawn from individual studied variables alone. Of the 12 genotypes analyzed, three genotypes showed significant trends for modifications in both morphology and immunolabeling. Six genotypes showed significant trends for modifications in either morphology or immunocoverage. The remaining three genotypes did not show any significant trends for modification.

A Plumber's-Eye View of Xylem Water Transport in Woody Plants

Science.gov (United States)

Martinez-Vilalta, Jordi; Pinol, Josep

2004-01-01

We present a practical for university-level students aimed at measuring and comparing xylem hydraulic properties of co-existing plant species. After sampling branches of several woody species in the field, their main hydraulic properties were measured using a simple set-up. Hydraulic conductivity ("K[subscript h]") was calculated as the ratio…

The Differential Effects of the Blue-Stain Fungus Leptographium qinlingensis on Monoterpenes and Sesquiterpenes in the Stem of Chinese White Pine (Pinus armandi Saplings

Directory of Open Access Journals (Sweden)

Thanh Pham

2014-11-01

Full Text Available When conifers such as Chinese white pine (Pinus armandi Fr. are attacked by insects or pathogens, they respond by increasing their content of monoterpenes and sesquiterpenes. In this study, we determined the effects of the blue-stain fungus Leptographium qinlingensis Tang and Chen on monoterpenes and sesquiterpenes in the phloem and xylem of the stem of P. armandi saplings. We found that the total monoterpene concentrations in the phloem and xylem of the stem and the total sesquiterpene concentrations in the xylem of the stem were significantly higher in L. qinlingensis-inoculated saplings than in control (mechanically wounded saplings or untreated saplings. Additionally, the proportions of β-pinene in the xylem of the stem and limonene + β-phellandrene in the phloem and xylem of the stem were significantly higher in L. qinlingensis-inoculated saplings than in both control and untreated saplings. The proportions of individual sesquiterpenes in the phloem and xylem of the stem were significantly greater in L. qinlingensis-inoculated saplings than in untreated saplings. Based on the results of this study, we suggest that increases in total monoterpene and sesquiterpene concentrations, as well as increases in the concentrations of β-pinene and limonene + β-phellandrene, may play an important defensive role against blue-stain fungus L. qinlingensis inoculation.

Tree differences in primary and secondary growth drive convergent scaling in leaf area to sapwood area across Europe.

Science.gov (United States)

Petit, Giai; von Arx, Georg; Kiorapostolou, Natasa; Lechthaler, Silvia; Prendin, Angela Luisa; Anfodillo, Tommaso; Caldeira, Maria C; Cochard, Hervé; Copini, Paul; Crivellaro, Alan; Delzon, Sylvain; Gebauer, Roman; Gričar, Jožica; Grönholm, Leila; Hölttä, Teemu; Jyske, Tuula; Lavrič, Martina; Lintunen, Anna; Lobo-do-Vale, Raquel; Peltoniemi, Mikko; Peters, Richard L; Robert, Elisabeth M R; Roig Juan, Sílvia; Senfeldr, Martin; Steppe, Kathy; Urban, Josef; Van Camp, Janne; Sterck, Frank

2018-06-01

Trees scale leaf (A L ) and xylem (A X ) areas to couple leaf transpiration and carbon gain with xylem water transport. Some species are known to acclimate in A L  : A X balance in response to climate conditions, but whether trees of different species acclimate in A L  : A X in similar ways over their entire (continental) distributions is unknown. We analyzed the species and climate effects on the scaling of A L vs A X in branches of conifers (Pinus sylvestris, Picea abies) and broadleaved (Betula pendula, Populus tremula) sampled across a continental wide transect in Europe. Along the branch axis, A L and A X change in equal proportion (isometric scaling: b ˜ 1) as for trees. Branches of similar length converged in the scaling of A L vs A X with an exponent of b = 0.58 across European climates irrespective of species. Branches of slow-growing trees from Northern and Southern regions preferentially allocated into new leaf rather than xylem area, with older xylem rings contributing to maintaining total xylem conductivity. In conclusion, trees in contrasting climates adjust their functional balance between water transport and leaf transpiration by maintaining biomass allocation to leaves, and adjusting their growth rate and xylem production to maintain xylem conductance. © 2018 The Authors. New Phytologist © 2018 New Phytologist Trust.

Vegetation and Ecological Characteristics of Mixed-Conifer and Red Fir Forests at the Teakettle Experimental Forest

Science.gov (United States)

Malcolm North; Brian Oakley; Jiquan Chen; Heather Erickson; Andrew Gray; Antonio Izzo; Dale Johnson; Siyan Ma; Jim Marra; Marc Meyer; Kathryn Purcell; Tom Rambo; Dave Rizzo; Brent Roath; Tim. Schowalter

2002-01-01

Detailed analysis of mixed-conifer and red fir forests were made from extensive, large vegetation sampling, systematically conducted throughout the Teakettle Experimental Forest. Mixed conifer is characterized by distinct patch conditions of closed-canopy tree clusters, persistent gaps and shrub thickets. This heterogeneous spatial structure provides contrasting...

Altitudinal variations of ground tissue and xylem tissue in terminal shoot of woody species: implications for treeline formation.

Science.gov (United States)

Chen, Hong; Wang, Haiyang; Liu, Yanfang; Dong, Li

2013-01-01

1. The terminal shoot (or current-year shoot), as one of the most active parts on a woody plant, is a basic unit determining plant height and is potentially influenced by a variety of environmental factors. It has been predicted that tissues amount and their allocation in plant stems may play a critical role in determining plant size in alpine regions. The primary structure in terminal shoots is a key to our understanding treeline formation. The existing theories on treeline formation, however, are still largely lacking of evidence at the species level, much less from anatomy for the terminal shoot. 2. The primary structures within terminal shoot were measured quantitatively for 100 species from four elevation zones along the eastern slope of Gongga Mountain, southwestern China; one group was sampled from above the treeline. An allometric approach was employed to examine scaling relationships interspecifically, and a principal components analysis (PCA) was performed to test the relation among primary xylem, ground tissue, species growth form and altitude. 3. The results showed that xylem tissue size was closely correlated with ground tissue size isometrically across species, while undergoing significant y- or/and x-intercept shift in response to altitudinal belts. Further, a conspicuous characteristic of terminal shoot was its allocation of contrasting tissues between primary xylem and ground tissues with increasing elevation. The result of the PCA showed correlations between anatomical variation, species growth form/height classes and environment. 4. The current study presents a comparative assessment of the allocation of tissue in terminal shoot across phylogenically and ecologically diverse species, and analyzes tissue, function and climate associations with plant growth forms and height classes among species. The interspecific connection between primary xylem ratio and plant size along an elevation gradient suggests the importance of primary xylem in explaining

Altitudinal variations of ground tissue and xylem tissue in terminal shoot of woody species: implications for treeline formation.

Directory of Open Access Journals (Sweden)

Hong Chen

Full Text Available 1. The terminal shoot (or current-year shoot, as one of the most active parts on a woody plant, is a basic unit determining plant height and is potentially influenced by a variety of environmental factors. It has been predicted that tissues amount and their allocation in plant stems may play a critical role in determining plant size in alpine regions. The primary structure in terminal shoots is a key to our understanding treeline formation. The existing theories on treeline formation, however, are still largely lacking of evidence at the species level, much less from anatomy for the terminal shoot. 2. The primary structures within terminal shoot were measured quantitatively for 100 species from four elevation zones along the eastern slope of Gongga Mountain, southwestern China; one group was sampled from above the treeline. An allometric approach was employed to examine scaling relationships interspecifically, and a principal components analysis (PCA was performed to test the relation among primary xylem, ground tissue, species growth form and altitude. 3. The results showed that xylem tissue size was closely correlated with ground tissue size isometrically across species, while undergoing significant y- or/and x-intercept shift in response to altitudinal belts. Further, a conspicuous characteristic of terminal shoot was its allocation of contrasting tissues between primary xylem and ground tissues with increasing elevation. The result of the PCA showed correlations between anatomical variation, species growth form/height classes and environment. 4. The current study presents a comparative assessment of the allocation of tissue in terminal shoot across phylogenically and ecologically diverse species, and analyzes tissue, function and climate associations with plant growth forms and height classes among species. The interspecific connection between primary xylem ratio and plant size along an elevation gradient suggests the importance of primary

Exploring the determinants of phylogenetic diversity and assemblage structure in conifers across temporal, spatial, and taxonomic scales

DEFF Research Database (Denmark)

Eiserhardt, Wolf L.; Borchsenius, Finn; Sandel, Brody Steven

-environmental models are important elements in this framework. Here, we integrate both types of data in order to explore the determinants of forest tree diversity using the conifers as a model group. Conifers are an old, diverse (ca. 650 spp. in 6 families) and widespread group of woody plants of high ecological...... and economic importance. They are better studied than most other globally distributed groups of forest trees, allowing integrative studies with high phylogenetic and spatial resolution. We analyse phylogenetic diversity, assemblage structure, and diversification rates for regional conifer assemblages...

Assessing inter- and intraspecific variability of xylem vulnerability to embolism in oaks

DEFF Research Database (Denmark)

Lobo, Albin; Torres-Ruiz, José M.; Burlett, Regis

2018-01-01

for future afforestation. However, the presence of long vessels makes it difficult to assess xylem vulnerability to embolism in these species. Thanks to the development of a flow centrifuge equipped with a large rotor, we quantified (i) the between species variability of embolism resistance in four native...

A low cost apparatus for measuring the xylem hydraulic conductance in plants

Directory of Open Access Journals (Sweden)

Luciano Pereira

2012-01-01

Full Text Available Plant yield and resistance to drought are directly related to the efficiency of the xylem hydraulic conductance and the ability of this system to avoid interrupting the flow of water. In this paper we described in detail the assembling of an apparatus proposed by TYREE et al. (2002, and its calibration, as well as low cost adaptations that make the equipment accessible for everyone working in this research area. The apparatus allows measuring the conductance in parts of roots or shoots (root ramifications or branches, or in the whole system, in the case of small plants or seedlings. The apparatus can also be used to measure the reduction of conductance by embolism of the xylem vessels. Data on the hydraulic conductance of eucalyptus seedlings obtained here and other reports in the literature confirm the applicability of the apparatus in physiological studies on the relationship between productivity and water stress.

Electrodeposition and characterization of nanocrystalline CoNiFe films

Energy Technology Data Exchange (ETDEWEB)

Chen, Y.; Wang, Q.P. [Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang 310027 (China); Cai, C. [School of Chemistry and chemical engineering, Ningxia University, Yinchuan 750021 (China); Yuan, Y.N. [Department of Materials and Chemistry, Zhejiang University, Hangzhou, Zhejiang 310027 (China); Cao, F.H. [Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang 310027 (China); Zhang, Z., E-mail: eaglezzy@zjuem.zju.edu.cn [Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang 310027 (China); Zhang, J.Q. [Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang 310027 (China); State Key Laboratory for Corrosion and Protection of Metals, Shenyang 110016 (China)

2012-02-29

Nanocrystalline Co{sub 45}Ni{sub 10}Fe{sub 24} films have been fabricated using cyclic voltammetry technique from the solutions containing sulfate, then characterized by scanning electron microscopy, X-ray diffraction and vibrating sample magnetometer. Meanwhile, Electrochemical Impedance Spectroscopy technique has been employed to probe into the nucleation/growth behavior of Co{sub 45}Ni{sub 10}Fe{sub 24} films. The results show that, the obtained Co{sub 45}Ni{sub 10}Fe{sub 24} film possesses low coercivity of 973.3 A/m and high saturation magnetic flux density of 1.59 Multiplication-Sign 10{sup 5} A/m. Under the experimental conditions, the nucleation/growth process of Co{sub 45}Ni{sub 10}Fe{sub 24} films is mainly under activation control. With the increase of the applied cathodic potential bias, the charge transfer resistance for CoNiFe deposition decreases exponentially. - Highlights: Black-Right-Pointing-Pointer Nanocrystalline Co{sub 45}Ni{sub 10}Fe{sub 24} film is obtained using cyclic voltammetry technique. Black-Right-Pointing-Pointer Nanocrystalline Co{sub 45}Ni{sub 10}Fe{sub 24} possesses low coercivity of 973.3 A/m. Black-Right-Pointing-Pointer Nanocrystalline Co{sub 45}Ni{sub 10}Fe{sub 24} possesses high saturation magnetic flux density. Black-Right-Pointing-Pointer The nucleation/growth process of CoNiFe films is mainly under activation control. Black-Right-Pointing-Pointer The charge transfer resistance for CoNiFe deposition decreases exponentially.

Specific and sensitive detection of the conifer pathogen Gremmeniella abietina by nested PCR

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Hansson Per

2005-11-01

Full Text Available Abstract Background Gremmeniella abietina (Lagerb. Morelet is an ascomycete fungus that causes stem canker and shoot dieback in many conifer species. The fungus is widespread and causes severe damage to forest plantations in Europe, North America and Asia. To facilitate early diagnosis and improve measures to control the spread of the disease, rapid, specific and sensitive detection methods for G. abietina in conifer hosts are needed. Results We designed two pairs of specific primers for G. abietina based on the 18S rDNA sequence variation pattern. These primers were validated against a wide range of fungi and 14 potential conifer hosts. Based on these specific primers, two nested PCR systems were developed. The first system employed universal fungal primers to enrich the fungal DNA targets in the first round, followed by a second round selective amplification of the pathogen. The other system employed G. abietina-specific primers in both PCR steps. Both approaches can detect the presence of G. abietina in composite samples with high sensitivity, as little as 7.5 fg G. abietina DNA in the host genomic background. Conclusion The methods described here are rapid and can be applied directly to a wide range of conifer species, without the need for fungal isolation and cultivation. Therefore, it represents a promising alternative to disease inspection in forest nurseries, plantations and quarantine control facilities.

Xylem anatomical responses of Vaccinium myrtillus exposed to air CO2 enrichment and soil warming at treeline

Science.gov (United States)

Anadon-Rosell, Alba; Fonti, Patrick; Dawes, Melissa; von Arx, Georg

2016-04-01

Plant life at treeline is limited by harsh growth conditions. In this study we used nine years of free air CO2 enrichment (+200 ppm from 2001 to 2009) and six years of soil warming (+4 °C from 2007 to 2012) at a treeline experimental site in the Swiss Alps to investigate xylem anatomical responses of Vaccinium myrtillus, a co-dominant dwarf shrub in many treeline communities. Our aim was to identify whether the release from limiting growth conditions induced adjustments of the water conductive and storage tissues. High-resolution images of wood anatomical microsections from the stem base of 40 individuals were captured with a digital camera mounted on a microscope. We used the specialized image analysis tool ROXAS to quantify size, density, grouping patterns, and potential hydraulic conductivity of vessels. In addition, we measured the abundance and distribution of ray parenchyma. Our preliminary results show that CO2 enrichment and soil warming induced contrasting anatomical responses. In the last years of the CO2 enhancement vessels were larger, whereas soil warming induced an immediate reduction of vessel size. Moreover, larger vessels were found when V. myrtillus was in cohabitation with pine as opposed to larch. Results for ray parenchyma measurements did not show clear trends, although warming seemed to have a slightly positive effect on the fraction of uniseriate vs. multiseriate rays. These results suggest that release from the growth limiting factors can result in contrasting and partially lagged responses in the hydraulic system with little impact on the storage tissues. In addition, the overstory species seem to play a key role on the anatomy of V. myrtillus at treeline.

Mixed xylem and phloem sap ingestion in sheath-feeders as normal dietary behavior: Evidence from the leafhopper Scaphoideus titanus.

Science.gov (United States)

Chuche, Julien; Sauvion, Nicolas; Thiéry, Denis

2017-10-01

In phytophagous piercing-sucking insects, salivary sheath-feeding species are often described as xylem- or phloem-sap feeding specialists. Because these two food sources have very different characteristics, two feeding tactics are often associated with this supposed specialization. Studying the feeding behavior of insects provides substantial information on their biology, ecology, and evolution. Furthermore, study of feeding behavior is of primary importance to elucidate the transmission ability of insects that act as vectors of plant pathogens. In this study, we compared the durations of ingestion performed in xylem versus phloem by a leafhopper species, Scaphoideus titanus Ball, 1932. This was done by characterizing and statistically analyzing electrical signals recorded using the electropenetrography technique, derived from the feeding behaviors of males and females. We identified three groups of S. titanus based on their feeding behavior: 1) a group that reached the phloem quickly and probed for a longer time in phloem tissue than the other groups, 2) a group that reached the xylem quickly and probed for a longer time in xylem tissue than the other groups, and 3) a group where individuals did not ingest much sap. In addition, the numbers and durations of waveforms representing ingestion of xylem and phloem saps differed significantly depending on the sex of the leafhopper, indicating that the two sexes exhibit different feeding behaviors. Males had longer phloem ingestion events than did females, which indicates that males are greater phloem feeders than females. These differences are discussed, specifically in relation to hypotheses about evolution of sap feeding and phytoplasma transmission from plant to plant. Copyright © 2017 Elsevier Ltd. All rights reserved.

Silvics of North America: Volume 1. Conifers

Science.gov (United States)

Russell M Burns; Barbara H. Honkala; [Technical coordinators

1990-01-01

The silvical characteristics of about 200 forest tree species and varieties are described. Most are native to the 50 United States and Puerto Rico, but a few are introduced and naturalized. Information on habitat, life history, and genetics is given for 15 genera, 63 species, and 20 varieties of conifers and for 58 genera, 128 species, and 6 varieties of hardwoods....

Effects of the ultraviolet-B radiation (UV-B) on conifers: a review

International Nuclear Information System (INIS)

Laakso, K.; Huttunen, S.

1998-01-01

The current knowledge on conifer responses to enhanced ultraviolet-B (UV-B) radiation is mainly based on greenhouse or growth chamber experiments of one growing season in duration. However, the biomass losses observed in greenhouses do not occur in field-grown trees in their natural habitats. Moreover, the majority of the 20 conifer species studied have been 1-year-old seedlings, and no studies have been undertaken on mature trees. Fully grown needles, with their glaucous waxy surfaces and thick epidermal cells with both soluble and wall-bound UV-B screening metabolites, are well protected against UV-B radiation. However, it is not known whether these are sufficient protectants in young emerging needles or during the early spring period of high UV-B levels reflected from snow. In order to understand all the mechanisms that result in the protection of conifer needles against UV-B radiation, future research should focus on the epidermal layer, separating the waxes, cuticle and epidermal and hypodermal cells. Parallel studies should consist of wall-bound and soluble secondary metabolite analysis, antioxidant measurements and microscopic observations. (author)

Effects of Fe and Mn deficiencies on the protein profiles of tomato (Solanum lycopersicum) xylem sap as revealed by shotgun analyses.

Science.gov (United States)

Ceballos-Laita, Laura; Gutierrez-Carbonell, Elain; Takahashi, Daisuke; Abadía, Anunciación; Uemura, Matsuo; Abadía, Javier; López-Millán, Ana Flor

2018-01-06

The aim of this work was to study the effects of Fe and Mn deficiencies on the xylem sap proteome of tomato using a shotgun proteomic approach, with the final goal of elucidating plant response mechanisms to these stresses. This approach yielded 643 proteins reliably identified and quantified with 70% of them predicted as secretory. Iron and Mn deficiencies caused statistically significant and biologically relevant abundance changes in 119 and 118 xylem sap proteins, respectively. In both deficiencies, metabolic pathways most affected were protein metabolism, stress/oxidoreductases and cell wall modifications. First, results suggest that Fe deficiency elicited more stress responses than Mn deficiency, based on the changes in oxidative and proteolytic enzymes. Second, both nutrient deficiencies affect the secondary cell wall metabolism, with changes in Fe deficiency occurring via peroxidase activity, and in Mn deficiency involving peroxidase, Cu-oxidase and fasciclin-like arabinogalactan proteins. Third, the primary cell wall metabolism was affected by both nutrient deficiencies, with changes following opposite directions as judged from the abundances of several glycoside-hydrolases with endo-glycolytic activities and pectin esterases. Fourth, signaling pathways via xylem involving CLE and/or lipids as well as changes in phosphorylation and N-glycosylation also play a role in the responses to these stresses. Biological significance In spite of being essential for the delivery of nutrients to the shoots, our knowledge of xylem responses to nutrient deficiencies is very limited. The present work applies a shotgun proteomic approach to unravel the effects of Fe and Mn deficiencies on the xylem sap proteome. Overall, Fe deficiency seems to elicit more stress in the xylem sap proteome than Mn deficiency, based on the changes measured in proteolytic and oxido-reductase proteins, whereas both nutrients exert modifications in the composition of the primary and secondary

Tissue-type-specific transcriptome analysis identifies developing xylem-specific promoters in poplar.

Science.gov (United States)

Ko, Jae-Heung; Kim, Hyun-Tae; Hwang, Ildoo; Han, Kyung-Hwan

2012-06-01

Plant biotechnology offers a means to create novel phenotypes. However, commercial application of biotechnology in crop improvement programmes is severely hindered by the lack of utility promoters (or freedom to operate the existing ones) that can drive gene expression in a tissue-specific or temporally controlled manner. Woody biomass is gaining popularity as a source of fermentable sugars for liquid fuel production. To improve the quantity and quality of woody biomass, developing xylem (DX)-specific modification of the feedstock is highly desirable. To develop utility promoters that can drive transgene expression in a DX-specific manner, we used the Affymetrix Poplar Genome Arrays to obtain tissue-type-specific transcriptomes from poplar stems. Subsequent bioinformatics analysis identified 37 transcripts that are specifically or strongly expressed in DX cells of poplar. After further confirmation of their DX-specific expression using semi-quantitative PCR, we selected four genes (DX5, DX8, DX11 and DX15) for in vivo confirmation of their tissue-specific expression in transgenic poplars. The promoter regions of the selected DX genes were isolated and fused to a β-glucuronidase (GUS)-reported gene in a binary vector. This construct was used to produce transgenic poplars via Agrobacterium-mediated transformation. The GUS expression patterns of the resulting transgenic plants showed that these promoters were active in the xylem cells at early seedling growth and had strongest expression in the developing xylem cells at later growth stages of poplar. We conclude that these DX promoters can be used as a utility promoter for DX-specific biomass engineering. © 2012 The Authors. Plant Biotechnology Journal © 2012 Society for Experimental Biology, Association of Applied Biologists and Blackwell Publishing Ltd.

Identification of Xylem Occlusions Occurring in Cut Clematis (Clematis L., fam. Ranunculaceae Juss. Stems during Their Vase Life

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Agata Jedrzejuk

2012-01-01

Full Text Available During the vase life of cut stems obstruction of xylem vessels occurs due to microbial growth, formation of tyloses, deposition of materials in the lumen of xylem vessels and the presence of air emboli in the vascular system. Such obstructions may restrict water uptake and its transport towards upwards thus lowering their ornamental value and longevity of cut flowers. Clematis is a very attractive plant material which may be used as cut flower in floral compositions. Nothing is known about the histochemical or cytological nature of xylem blockages occurring in cut stems of this plant. This study shows that in clematis, tyloses are the main source of occlusions, although bacteria and some amorphic substances may also appear inside the vessels. A preservative composed of 200 mg dm−3 8-HQC (8-hydroxyquinolin citrate and 2% sucrose arrested bacterial development and the growth of tyloses. This information can be helpful in the development of new treatments to improve keeping qualities of cut clematis stems.

Fluxes of trichloroacetic acid through a conifer forest canopy

International Nuclear Information System (INIS)

Stidson, R.T.; Heal, K.V.; Dickey, C.A.; Cape, J.N.; Heal, M.R.

2004-01-01

Controlled-dosing experiments with conifer seedlings have demonstrated an above-ground route of uptake for trichloroacetic acid (TCA) from aqueous solution into the canopy, in addition to uptake from the soil. The aim of this work was to investigate the loss of TCA to the canopy in a mature conifer forest exposed only to environmental concentrations of TCA by analysing above- and below-canopy fluxes of TCA and within-canopy instantaneous reservoir of TCA. Concentrations and fluxes of TCA were quantified for one year in dry deposition, rainwater, cloudwater, throughfall, stemflow and litterfall in a 37-year-old Sitka spruce and larch plantation in SW Scotland. Above-canopy TCA deposition was dominated by rainfall (86%), compared with cloudwater (13%) and dry deposition (1%). On average only 66% of the TCA deposition passed through the canopy in throughfall and stemflow (95% and 5%, respectively), compared with 47% of the wet precipitation depth. Consequently, throughfall concentration of TCA was, on average, ∼1.4 x rainwater concentration. There was no significant difference in below-canopy fluxes between Sitka spruce and larch, or at a forest-edge site. Annual TCA deposited from the canopy in litterfall was only ∼1-2% of above-canopy deposition. On average, ∼800 μg m -2 of deposited TCA was lost to the canopy per year, compared with estimates of above-ground TCA storage of ∼400 and ∼300 μg m -2 for Sitka spruce and larch, respectively. Taking into account likely uncertainties in these values (∼±50%), these data yield an estimate for the half-life of within-canopy elimination of TCA in the range 50-200 days, assuming steady-state conditions and that all TCA lost to the canopy is transferred into the canopy material, rather than degraded externally. The observations provide strong indication that an above-ground route is important for uptake of TCA specifically of atmospheric origin into mature forest canopies, as has been shown for seedlings (in

Xylem anatomy correlates with gas exchange, water-use efficiency and growth performance under contrasting water regimes: evidence from Populus deltoides x Populus nigra hybrids.

Science.gov (United States)

Fichot, Régis; Laurans, Françoise; Monclus, Romain; Moreau, Alain; Pilate, Gilles; Brignolas, Franck

2009-12-01

Six Populus deltoides Bartr. ex Marsh. x P. nigra L. genotypes were selected to investigate whether stem xylem anatomy correlated with gas exchange rates, water-use efficiency (WUE) and growth performance. Clonal copies of the genotypes were grown in a two-plot common garden test under contrasting water regimes, with one plot maintained irrigated and the other one subjected to moderate summer water deficit. The six genotypes displayed a large range of xylem anatomy, mean vessel and fibre diameter varying from about 40 to 60 microm and from 7.5 to 10.5 microm, respectively. Decreased water availability resulted in a reduced cell size and an important rise in vessel density, but the extent of xylem plasticity was both genotype and trait dependent. Vessel diameter and theoretical xylem-specific hydraulic conductivity correlated positively with stomatal conductance, carbon isotope discrimination and growth performance-related traits and negatively with intrinsic WUE, especially under water deficit conditions. Vessel diameter and vessel density measured under water deficit conditions correlated with the relative losses in biomass production in response to water deprivation; this resulted from the fact that a more plastic xylem structure was generally accompanied by a larger loss in biomass production.

Source of sustained voltage difference between the xylem of a potted Ficus benjamina tree and its soil.

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Christopher J Love

Full Text Available It has long been known that there is a sustained electrical potential (voltage difference between the xylem of many plants and their surrounding soil, but the mechanism behind this voltage has remained controversial. After eliminating any extraneous capacitive or inductive couplings and ground-mediated electric current flows, we have measured sustained differences of 50-200 mV between the xylem region of a Faraday-caged, intact, potted Ficus benjamina tree and its soil, as well as between its cut branches and soils and ionic solutions standardized to various pH values. Using identical platinum electrodes, no correlation between the voltage and time of day, illumination, sap flow, electrode elevation, or ionic composition of soil was found, suggesting no direct connection to simple dissimilar-metal redox reactions or transpirational activity. Instead, a clear relationship between the voltage polarity and magnitude and the pH difference between xylem and soil was observed. We attribute these sustained voltages to a biological concentration cell likely set up by the homeostatic mechanisms of the tree. Potential applications of this finding are briefly explored.

Aberrant Classopollis pollen reveals evidence for unreduced (2n) pollen in the conifer family Cheirolepidiaceae during the Triassic–Jurassic transition

Science.gov (United States)

Kürschner, Wolfram M.; Batenburg, Sietske J.; Mander, Luke

2013-01-01

Polyploidy (or whole-genome doubling) is a key mechanism for plant speciation leading to new evolutionary lineages. Several lines of evidence show that most species among flowering plants had polyploidy ancestry, but it is virtually unknown for conifers. Here, we study variability in pollen tetrad morphology and the size of the conifer pollen type Classopollis extracted from sediments of the Triassic–Jurassic transition, 200 Ma. Classopollis producing Cheirolepidiaceae were one of the most dominant and diverse groups of conifers during the Mesozoic. We show that aberrant pollen Classopollis tetrads, triads and dyads, and the large variation in pollen size indicates the presence of unreduced (2n) pollen, which is one of the main mechanisms in modern polyploid formation. Polyploid speciation may explain the high variability of growth forms and adaptation of these conifers to different environments and their resistance to extreme growth conditions. We suggest that polyploidy may have also reduced the extinction risk of these conifers during the End-Triassic biotic crisis. PMID:23926159

Interpreting the Climatic Effects on Xylem Functional Traits in Two Mediterranean Oak Species: The Role of Extreme Climatic Events.

Science.gov (United States)

Rita, Angelo; Borghetti, Marco; Todaro, Luigi; Saracino, Antonio

2016-01-01

In the Mediterranean region, the widely predicted rise in temperature, change in the precipitation pattern, and increase in the frequency of extreme climatic events are expected to alter the shape of ecological communities and to affect plant physiological processes that regulate ecosystem functioning. Although change in the mean values are important, there is increasing evidence that plant distribution, survival, and productivity respond to extremes rather than to the average climatic condition. The present study aims to assess the effects of both mean and extreme climatic conditions on radial growth and functional anatomical traits using long-term tree-ring time series of two co-existing Quercus spp. from a drought-prone site in Southern Italy. In particular, this is the first attempt to apply the Generalized Additive Model for Location, Scale, and Shape (GAMLSS) technique and Bayesian modeling procedures to xylem traits data set, with the aim of (i) detecting non-linear long-term responses to climate and (ii) exploring relationships between climate extreme and xylem traits variability in terms of probability of occurrence. This study demonstrates the usefulness of long-term xylem trait chronologies as records of environmental conditions at annual resolution. Statistical analyses revealed that most of the variability in tree-ring width and specific hydraulic conductivity might be explained by cambial age. Additionally, results highlighted appreciable relationships between xylem traits and climate variability more than tree-ring width, supporting also the evidence that the plant hydraulic traits are closely linked to local climate extremes rather than average climatic conditions. We reported that the probability of extreme departure in specific hydraulic conductivity (Ks) rises at extreme values of Standardized Precipitation Index (SPI). Therefore, changing frequency or intensity of extreme events might overcome the adaptive limits of vascular transport, resulting

Interpreting the climatic effects on xylem functional traits in two Mediterranean oak species: the role of extreme climatic events

Directory of Open Access Journals (Sweden)

Angelo Rita

2016-08-01

Full Text Available In the Mediterranean region, the widely predicted rise in temperature, change in the precipitation pattern and increase in the frequency of extreme climatic events are expected to alter the shape of ecological communities and to affect plant physiological processes that regulate ecosystem functioning. Although change in the mean values are important, there is increasing evidence that plant distribution, survival and productivity respond to extremes rather than to the average climatic condition. The present study aims to assess the effects of both mean and extreme climatic conditions on radial growth and functional anatomical traits using long-term tree-ring time series of two co-existing Quercus spp. from a drought-prone site in Southern Italy. In particular, this is the first attempt to apply the Generalized Additive Model for Location, Scale and Shape (GAMLSS technique and Bayesian modeling procedures to xylem traits data set, with the aim of i detecting non-linear long-term responses to climate and ii exploring relationships between climate extreme and xylem traits variability in terms of probability of occurrence. This study demonstrates the usefulness of long-term xylem trait chronologies as records of environmental conditions at annual resolution. Statistical analyses revealed that most of the variability in tree-ring width and specific hydraulic conductivity might be explained by cambial age. Additionally, results highlighted appreciable relationships between xylem traits and climate variability more than tree-ring width, supporting also the evidence that the plant hydraulic traits are closely linked to local climate extremes rather than average climatic conditions. We reported that the probability of extreme departure in specific hydraulic conductivity (Ks rises at extreme values of Standardized Precipitation Index (SPI. Therefore, changing frequency or intensity of extreme events might overcome the adaptive limits of vascular transport

Concentrations and content of mercury in bark, wood, and leaves in hardwoods and conifers in four forested sites in the northeastern USA

Science.gov (United States)

Yanai, Ruth D.; Driscoll, Charles T.; Montesdeoca, Mario; Smith, Kevin T.

2018-01-01

Mercury (Hg) is deposited from the atmosphere to remote areas such as forests, but the amount of Hg in trees is not well known. To determine the importance of Hg in trees, we analyzed foliage, bark and bole wood of eight tree species at four sites in the northeastern USA (Huntington Forest, NY; Sleepers River, VT; Hubbard Brook, NH; Bear Brook, ME). Foliar concentrations of Hg averaged 16.3 ng g-1 among the hardwood species, which was significantly lower than values in conifers, which averaged 28.6 ng g-1 (p < 0.001). Similarly, bark concentrations of Hg were lower (p < 0.001) in hardwoods (7.7 ng g-1) than conifers (22.5 ng g-1). For wood, concentrations of Hg were higher in yellow birch (2.1–2.8 ng g-1) and white pine (2.3 ng g-1) than in the other species, which averaged 1.4 ng g-1 (p < 0.0001). Sites differed significantly in Hg concentrations of foliage and bark (p = 0.02), which are directly exposed to the atmosphere, but the concentration of Hg in wood depended more on species (p < 0.001) than site (p = 0.60). The Hg contents of tree tissues in hardwood stands, estimated from modeled biomass and measured concentrations at each site, were higher in bark (mean of 0.10 g ha-1) and wood (0.16 g ha-1) than in foliage (0.06 g ha-1). In conifer stands, because foliar concentrations were higher, the foliar pool tended to be more important. Quantifying Hg in tree tissues is essential to understanding the pools and fluxes of Hg in forest ecosystems. PMID:29684081

Concentrations and content of mercury in bark, wood, and leaves in hardwoods and conifers in four forested sites in the northeastern USA.

Science.gov (United States)

Yang, Yang; Yanai, Ruth D; Driscoll, Charles T; Montesdeoca, Mario; Smith, Kevin T

2018-01-01

Mercury (Hg) is deposited from the atmosphere to remote areas such as forests, but the amount of Hg in trees is not well known. To determine the importance of Hg in trees, we analyzed foliage, bark and bole wood of eight tree species at four sites in the northeastern USA (Huntington Forest, NY; Sleepers River, VT; Hubbard Brook, NH; Bear Brook, ME). Foliar concentrations of Hg averaged 16.3 ng g-1 among the hardwood species, which was significantly lower than values in conifers, which averaged 28.6 ng g-1 (p < 0.001). Similarly, bark concentrations of Hg were lower (p < 0.001) in hardwoods (7.7 ng g-1) than conifers (22.5 ng g-1). For wood, concentrations of Hg were higher in yellow birch (2.1-2.8 ng g-1) and white pine (2.3 ng g-1) than in the other species, which averaged 1.4 ng g-1 (p < 0.0001). Sites differed significantly in Hg concentrations of foliage and bark (p = 0.02), which are directly exposed to the atmosphere, but the concentration of Hg in wood depended more on species (p < 0.001) than site (p = 0.60). The Hg contents of tree tissues in hardwood stands, estimated from modeled biomass and measured concentrations at each site, were higher in bark (mean of 0.10 g ha-1) and wood (0.16 g ha-1) than in foliage (0.06 g ha-1). In conifer stands, because foliar concentrations were higher, the foliar pool tended to be more important. Quantifying Hg in tree tissues is essential to understanding the pools and fluxes of Hg in forest ecosystems.

Analysis of conifer forest regeneration using Landsat Thematic Mapper data

Science.gov (United States)

Fiorella, Maria; Ripple, William J.

1995-01-01

Landsat Thematic Mapper (TM) data were used to evaluate young conifer stands in the western Cascade Mountains of Oregon. Regression and correlation analyses were used to describe the relationships between TM band values and age of young Douglas-fir stands (2 to 35 years old). Spectral data from well regenerated Douglas-fir stands were compared to those of poorly regenerated conifer stands. TM bands 1, 2, 3, 5, 6, and 7 were inversely correlated with the age (r greater than or equal to -0.80) of well regenerated Douglas-fir stands. Overall, the 'structural index' (TM 4/5 ratio) had the highest correlation to age of Douglas-fir stands (r = 0.96). Poorly regenerated stands were spectrally distinct from well regenerated Douglas-fir stands after the stands reached an age of approximately 15 years.

Soil water and xylem chemistry in declining sugar maple stands in Pennsylvania

Science.gov (United States)

David R. DeWalle; Bryan R. Swistock; William E. Sharpe

1999-01-01

Evidence is accumulating that decline of sugar maple, Acer saccharum Marsh., in northern Pennsylvania may be related to overall site fertility as reflected in the chemistry of soil water and bolewood xylem. In this paper we discuss factors related to varying site fertility, including effects of soil liming, past glacialion, topographic position and...

Processes and xylem anatomical properties involved in rehydration dynamics of cut flowers

NARCIS (Netherlands)

Meeteren, van U.; Ieperen, van W.; Nijsse, J.; Scheenen, T.W.J.; As, van H.; Keijzer, C.J.

2001-01-01

In cut flowers, which are harvested in air and transported dry, all cut xylem vessels in the basal part of the stem contain air instead of water. These air-emboli initially block water transport at the start of vase life, but usually (partly) disappear during the first hours of vase life, resulting

Are needles of Pinus pinaster more vulnerable to xylem embolism than branches? New insights from X-ray computed tomography.

Science.gov (United States)

Bouche, Pauline S; Delzon, Sylvain; Choat, Brendan; Badel, Eric; Brodribb, Timothy J; Burlett, Regis; Cochard, Hervé; Charra-Vaskou, Katline; Lavigne, Bruno; Li, Shan; Mayr, Stefan; Morris, Hugh; Torres-Ruiz, José M; Zufferey, Vivian; Jansen, Steven

2016-04-01

Plants can be highly segmented organisms with an independently redundant design of organs. In the context of plant hydraulics, leaves may be less embolism resistant than stems, allowing hydraulic failure to be restricted to distal organs that can be readily replaced. We quantified drought-induced embolism in needles and stems of Pinus pinaster using high-resolution computed tomography (HRCT). HRCT observations of needles were compared with the rehydration kinetics method to estimate the contribution of extra-xylary pathways to declining hydraulic conductance. High-resolution computed tomography images indicated that the pressure inducing 50% of embolized tracheids was similar between needle and stem xylem (P50 needle xylem  = -3.62 MPa, P50 stem xylem  = -3.88 MPa). Tracheids in both organs showed no difference in torus overlap of bordered pits. However, estimations of the pressure inducing 50% loss of hydraulic conductance at the whole needle level by the rehydration kinetics method were significantly higher (P50 needle  = -1.71 MPa) than P50 needle xylem derived from HRCT. The vulnerability segmentation hypothesis appears to be valid only when considering hydraulic failure at the entire needle level, including extra-xylary pathways. Our findings suggest that native embolism in needles is limited and highlight the importance of imaging techniques for vulnerability curves. © 2015 John Wiley & Sons Ltd.

Conifer fibers as reinforcing materials for polypropylene-based composites

DEFF Research Database (Denmark)

Plackett, David; Chengzhi, Chuai; Almdal, Kristoffer

2001-01-01

in improved processing, as well as improvements in the thermal and mechanical properties of the resultant composites compared with the composites filled with untreated conifer fibers. Moreover, MAPP grafting and MAPP treating displayed more obvious benefits than EPDM treating in terms of thermal properties...

Recurrent abnormalities in conifer cones and the evolutionary origins of flower-like structures.

Science.gov (United States)

Rudall, Paula J; Hilton, Jason; Vergara-Silva, Francisco; Bateman, Richard M

2011-03-01

Conifer cones are reproductive structures that are typically of restricted growth and either exclusively pollen-bearing (male) or exclusively ovule-bearing (female). Here, we review two common spontaneous developmental abnormalities of conifer cones: proliferated cones, in which the apex grows vegetatively, and bisexual cones, which possess both male and female structures. Emerging developmental genetic data, combined with evidence from comparative morphology, ontogeny and palaeobotany, provide new insights into the evolution of both cones and flowers, and prompt novel strategies for understanding seed-plant evolution. Copyright © 2010 Elsevier Ltd. All rights reserved.

Oviposition strategies of conifer seed chalcids in relation to host phenology

Science.gov (United States)

Rouault, Gaëlle; Turgeon, Jean; Candau, Jean-Noël; Roques, Alain; Aderkas, Patrick

2004-10-01

Insects are considered the most important predators of seed cones, the female reproductive structures of conifers, prior to seed dispersal. Slightly more than 100 genera of insects are known to parasitize conifer seed cones. The most diverse (i.e., number of species) of these genera is Megastigmus (Hymenoptera: Torymidae), which comprises many important seed pests of native and exotic conifers. Seed chalcids, Megastigmus spp., lay eggs inside the developing ovules of host conifers and, until recently, oviposition was believed to occur only in fertilized ovules. Ovule development begins just after pollination, but stops if cells are not fertilized. The morphological stage of cone development at the time of oviposition by seed chalcids has been established for many species; however, knowledge of ovule development at that time has been documented for only one species, M. spermotrophus. Megastigmus spermotrophus oviposits in Douglas-fir ovules after pollination but before fertilization. Unlike the unfertilized ovules, those containing a M. spermotrophus larva continue to develop, whether fertilized or not, stressing the need to broaden our understanding of the insect plant interactions for this entire genus. To achieve this task, we reviewed the scientific literature and assembled information pertaining to the timing of oviposition and to the pollination and fertilization periods of their respective host(s). More specifically, we were searching for circumstantial evidence that other species of Megastigmus associated with conifers could behave (i.e., oviposit before ovule fertilization) and impact on female gametophyte (i.e., prevent abortion) like M. spermotrophus. The evidence from our compilation suggests that seed chalcids infesting Pinaceae may also oviposit before ovule fertilization, just like M. spermotrophus, whereas those infesting Cupressaceae seemingly oviposit after ovule fertilization. Based on this evidence, we hypothesize that all species of Megastigmus

Drought, Frost, Rain and Sunshine. Four Years of Sap Flow Measurements for One of the World's Largest Conifers

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Macinnis-Ng, C.; Taylor, D. T.; Kaplick, J.; Clearwater, M.

2015-12-01

Amongst the largest and longest lived conifers in the world, the endemic New Zealand kauri, Agathis australis, provides a proxy-climate record dating back 4000 y. Tree-ring widths provide a strong indicator of the occurrence of El Niño Southern Oscillation (ENSO) events. We are measuring physiological processes, including carbon uptake and loss, leaf-scale gas exchange and sap flow together with meteorological data to explore the mechanisms of the climate response of this iconic and culturally significant species. In this continuous 15 min time interval sap flow dataset spanning four years, we have captured very wet and very dry summer periods. Winter flow rates peaked lower than summer flow rates and winter flow also started later and finished earlier in the day, resulting in less water use. Larger, canopy dominant trees (DBH up to 176 cm) had large sapwood area (sapwood depth up to 18 cm) and faster flow rates and therefore dominated stand water use. During dry periods, smaller trees (DBH 20-80 cm) were more responsive to dry soils than larger trees, suggesting access to deeper soil water stores. Leaf-scale gas exchange rates were low with very low stomatal conductance values reflecting known vulnerability to xylem embolism. Night-time refilling of sapwood was particularly evident during the summer drought with evidence that refilling was incomplete as the drought progressed. Photosynthetically active radiation and vapour pressure deficit are strongly correlated with sap flow across all seasons, a promising indicator for future modelling work on this dataset. Water saving strategies and stand-scale water budgets are discussed.

Biorhythms in conifer seed germination during extended storage

Science.gov (United States)

James P. Barnett; N.I. Marnonov

1989-01-01

A proportion of sound seeds of conifer species do not germinate during certain periods of the year, even when conditions are favorable. Mamonov et al. (1986) report that the non-germinating seeds have apparently undergone physiological changes that affected germination. This phenomenon may be due to seasonal periodicity, or biorhythms. As early as the mid-1930'...

Physiological plant investigations for the purpose of growing smoke resistant conifers

Energy Technology Data Exchange (ETDEWEB)

Polster, H; Bortitz, S; Vogl, M

1965-01-01

Spruce and pine are the main commercial wood varieties used in East Germany. These are also the most sensitive to smoke. Usually replacement of the damaged trees is necessary. The Department of Smoke Research of the Institute for Plant Chemistry of the Dresden Institute of Technology has been able to develop conifers resistant to SO2. In order to select smoke resistant trees for breeding, the Institute for Forestry and Plant Physiology of the Institute of Forestry Breeding in Graupa, East Germany has developed a rapid selection test. It is based on subjecting a small branch to doses of SO2. A method of breeding smoke resistant conifers is given in detail. It takes approximately ten years to produce the seeds.

Translocation of {sup 14}C-Labelled Substances and {sup 32}PO{sub 4} in Mistletoe-Infected and Uninfected Conifers and Dicotyledonous Trees

Energy Technology Data Exchange (ETDEWEB)

Leonard, O. A.; Hull, R. J. [University of California, Davis, CA (United States)

1966-05-15

Translocation studies, employing autoradiographic techniques, were conducted on eight dwarf mistletoe (Arceuthobium) infected hosts and eight green mistletoe (Phoradendron) infected hosts and uninfected hosts. These studies were conducted in the field at different seasons of the year over a 4-yr period. It was necessary to overcome the problem of pseudo-autoradiographs, especially prominent with conifers. These were overcome by using special film materials, such as Saran Wrap; this film excluded about 50% of the beta radiation. Translocation was studied using labelled substances applied to the host foliage, bark, wood, and mistletoe shoots. Labelled substances employed were {sup 14}CO{sub 2} (applied to host foliage and mistletoe shoots), {sup 14}C-labelled herbicides and {sup 32}PO{sub 4}. Phloem mobile substances translocated from the hosts into infecting dwarf mistletoes but not into green mistletoes. When the host branches were defoliated, phloem mobile Substances moved into them during the growing season. When dormant, very little transport into defoliated branches occurred, except when they were infected with dwarf mistletoes; in the latter situation, import was considerable into such branches and also into the infecting mistletoes. Phloem mobile substances in dwarf mistletoes migrated always in an apical direction, accumulating in the nodes, flowers, and fruit. In no instance was there any evidence of any basipetal transport (labelled assimilates 2,4-dichlorophenoxyacetic acid, 2, 4, 5-trichlorophenoxyacetic acid, 3-amino-1, 2,4-triazole, 2-chloro-4-ethylamino-6-isopropylamino-1, 3, 5-triazine, 1,1'-dimethyl-4,4',-bipyridylium-2A, urea and {sup 32}PO{sub 4}). In contrast to this, the green mistletoes moved substances within them in much the same manner as normal green plants; however, phloem mobile substances did not migrate significantly out of the endophytic system into the hosts, even when the host branches were defoliated. Xylem application was the most

Xylem sap nitrogen compounds of some Crotalaria species

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Vitória Angela Pierre

1999-01-01

Full Text Available Thirteen species of Crotalaria were analysed for nitrogen compounds in the xylem root bleeding sap. Amino acids were the main form of organic nitrogen found, but only traces of ureides were present. Of the four species analysed for amino acid composition, asparagine was found to be the major amino acid, accounting for over 68% of the nitrogen transported. No striking deviations from this general pattern was found between species, between vegetative and floral stages of development, or between nodulated and non-nodulated plants. It was concluded that the Crotalaria species studied here have an asparagine-based nitrogen metabolism, consistent with many other non-ureide-producing legume species.

Can Carbon Fluxes Explain Differences in Soil Organic Carbon Storage under Aspen and Conifer Forest Overstories?

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Antra Boča

2017-04-01

Full Text Available Climate- and management-induced changes in tree species distributions are raising questions regarding tree species-specific effects on soil organic carbon (SOC storage and stability. Quaking aspen (Populus tremuloides Michx. is the most widespread tree species in North America, but fire exclusion often promotes the succession to conifer dominated forests. Aspen in the Western US have been found to store more SOC in the mineral soil than nearby conifers, but we do not yet fully understand the source of this differential SOC accumulation. We measured total SOC storage (0–50 cm, characterized stable and labile SOC pools, and quantified above- and belowground litter inputs and dissolved organic carbon (DOC fluxes during snowmelt in plots located in N and S Utah, to elucidate the role of foliage vs. root detritus in SOC storage and stabilization in both ecosystems. While leaf litterfall was twice as high under aspen as under conifers, input of litter-derived DOC with snowmelt water was consistently higher under conifers. Fine root (<2 mm biomass, estimated root detritus input, and root-derived DOC fluxes were also higher under conifers. A strong positive relationship between root and light fraction C content suggests that root detritus mostly fueled the labile fraction of SOC. Overall, neither differences in above- and belowground detritus C inputs nor in detritus-derived DOC fluxes could explain the higher and more stable SOC pools under aspen. We hypothesize that root–microbe–soil interactions in the rhizosphere are more likely to drive these SOC pool differences.

Contrasting trait syndromes in angiosperms and conifers are associated with different responses of tree growth to temperature on a large scale

OpenAIRE

Carnicer i Cols, Jofre

2013-01-01

Recent large-scale studies of tree growth in the Iberian Peninsula reported contrasting positive and negative effects of temperature in Mediterranean angiosperms and conifers. Here we review the different hypotheses that may explain these trends and propose that the observed contrasting responses of tree growth to temperature in this region could be associated with a continuum of trait differences between angiosperms and conifers. Angiosperm and conifer trees differ in the effects of phenolog...

Contrasting trait syndromes in angiosperms and conifers are associated with different responses of tree growth to temperature on a large scale.

OpenAIRE

Jofre eCarnicer; Adria eBarbeta; Dominik eSperlich; Dominik eSperlich; Marta eColl; Josep ePenuelas

2013-01-01

Recent large-scale studies of tree growth in the Iberian Peninsula reported contrasting positive and negative effects of temperature in Mediterranean angiosperms and conifers. Here we review the different hypotheses that may explain these trends and propose that the observed contrasting responses of tree growth to temperature in this region could be associated with a continuum of trait differences between angiosperms and conifers. Angiosperm and conifer trees differ in the effects of phenolog...

Comparing growth phenology of co-occurring deciduous and evergreen conifers exposed to drought

OpenAIRE

Swidrak, Irene; Schuster, Roman; Oberhuber, Walter

2013-01-01

Plant phenological events are influenced by climate factors such as temperature and rainfall. To evaluate phenological responses to water availability in a Spring Heath-Pine wood (Erico-Pinetum typicum), the focus of this study was to determine intra-annual dynamics of apical and lateral growth of co-occurring early successional Larix decidua and Pinus sylvestris and late successional Picea abies exposed to drought. The effect of reduced plant water availability on growth phenology was invest...

Xylem anisotropy and water transport--a model for the double sawcut experiment

Science.gov (United States)

Paul J. Schulte; David G. Costa

2010-01-01

Early experiments with overlapping cuts to the stems of trees demonstrated that lateral flow within the stem must be possible to allow such trees to maintain water flow to their leaves. We present a mathematical approach to considering lateral flow in stems by treating the xylem as an anisotropic medium for flow and develop an expression of its conductivity in the form...

Analyzing 3D xylem networks in Vitis vinifera using High Resolution Computed Tomography (HRCT)

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Recent developments in High Resolution Computed Tomography (HRCT) have made it possible to visualize three dimensional (3D) xylem networks without time consuming, labor intensive physical sectioning. Here we describe a new method to visualize complex vessel networks in plants and produce a quantitat...

Transgenic poplars with reduced lignin show impaired xylem conductivity, growth efficiency and survival

Science.gov (United States)

Steven L. Voelker; Barbara Lachenbruch; Frederick C. Meinzer; Peter Kitin; Steven H. Strauss

2011-01-01

We studied xylem anatomy and hydraulic architecture in 14 transgenic insertion events and a control line of hybrid poplar (Populus spp.) that varied in lignin content. Transgenic events had different levels of down-regulation of two genes encoding 4-coumarate:coenzyme A ligase (4CL). Two-year-old trees were characterized after...

Flotation preferentially selects saccate pollen during conifer pollination.

Science.gov (United States)

Leslie, Andrew B

2010-10-01

• Among many species of living conifers the presence of pollen with air bladders (saccate pollen) is strongly associated with downward-facing ovules and the production of pollination drops. This combination of features enables saccate pollen grains captured in the pollination drop to float upwards into the ovule. Despite the importance of this mechanism in understanding reproduction in living conifers and in extinct seed plants with similar morphologies, experiments designed to test its effectiveness have yielded equivocal results. • In vitro and in vivo pollination experiments using saccate and nonsaccate pollen were performed using modeled ovules and two Pinus species during their natural pollination period. • Buoyant saccate pollen readily floated through aqueous droplets, separating these grains from nonbuoyant pollen and spores. Ovules that received saccate pollen, nonsaccate pollen or a mixture of both all showed larger amounts and higher proportions of saccate pollen inside ovules after drop secretion. • These results demonstrate that flotation is an effective mechanism of pollen capture and transport in gymnosperms, and suggest that the prevalence of saccate grains and downward-facing ovules in the evolutionary history of seed plants is a result of the widespread use of this mechanism.

The Paleocene Eocene carbon isotope excursion in higher plant organic matter: Differential fractionation of angiosperms and conifers in the Arctic

Science.gov (United States)

Schouten, Stefan; Woltering, Martijn; Rijpstra, W. Irene C.; Sluijs, Appy; Brinkhuis, Henk; Sinninghe Damsté, Jaap S.

2007-06-01

A study of upper Paleocene-lower Eocene (P-E) sediments deposited on the Lomonosov Ridge in the central Arctic Ocean reveals relatively high abundances of terrestrial biomarkers. These include dehydroabietane and simonellite derived from conifers (gymnosperms) and a tetra-aromatic triterpenoid derived from angiosperms. The relative percentage of the angiosperm biomarker of the summed angiosperm + conifer biomarkers was increased at the end of the Paleocene-Eocene thermal maximum (PETM), different when observed with pollen counts which showed a relative decrease in angiosperm pollen. Stable carbon isotopic analysis of these biomarkers shows that the negative carbon isotope excursion (CIE) during the PETM amounts to 3‰ for both conifer biomarkers, dehydroabietane and simonellite, comparable to the magnitude of the CIE inferred from marine carbonates, but significantly lower than the 4.5‰ of the terrestrial C 29n-alkane [M. Pagani, N. Pedentchouk, M. Huber, A. Sluijs, S. Schouten, H. Brinkhuis, J.S. Sinninghe Damsté, G.R. Dickens, and the IODP Expedition 302 Expedition Scientists (2006), Arctic's hydrology during global warming at the Paleocene-Eocene thermal maximum. Nature, 442, 671-675.], which is a compound sourced by both conifers and angiosperms. Conspicuously, the angiosperm-sourced aromatic triterpane shows a much larger CIE of 6‰ and suggests that angiosperms increased in their carbon isotopic fractionation during the PETM. Our results thus indicate that the 4.5‰ C 29n-alkane CIE reported previously represents the average CIE of conifers and angiosperms at this site and suggest that the large and variable CIE observed in terrestrial records may be partly explained by the variable contributions of conifers and angiosperms. The differential response in isotopic fractionation of angiosperms and conifers points to different physiological responses of these vegetation types to the rise in temperature, humidity, and greenhouse gases during the PETM.

Anti-transpirant activity in xylem sap from flooded tomato (Lycopersicon esculentum Mill.) plants is not due to pH-mediated redistributions of root- or shoot-sourced ABA.

Science.gov (United States)

Else, Mark A; Taylor, June M; Atkinson, Christopher J

2006-01-01

In flooded soils, the rapid effects of decreasing oxygen availability on root metabolic activity are likely to generate many potential chemical signals that may impact on stomatal apertures. Detached leaf transpiration tests showed that filtered xylem sap, collected at realistic flow rates from plants flooded for 2 h and 4 h, contained one or more factors that reduced stomatal apertures. The closure could not be attributed to increased root output of the glucose ester of abscisic acid (ABA-GE), since concentrations and deliveries of ABA conjugates were unaffected by soil flooding. Although xylem sap collected from the shoot base of detopped flooded plants became more alkaline within 2 h of flooding, this rapid pH change of 0.5 units did not alter partitioning of root-sourced ABA sufficiently to prompt a transient increase in xylem ABA delivery. More shoot-sourced ABA was detected in the xylem when excised petiole sections were perfused with pH 7 buffer, compared with pH 6 buffer. Sap collected from the fifth oldest leaf of "intact" well-drained plants and plants flooded for 3 h was more alkaline, by approximately 0.4 pH units, than sap collected from the shoot base. Accordingly, xylem [ABA] was increased 2-fold in sap collected from the fifth oldest petiole compared with the shoot base of flooded plants. However, water loss from transpiring, detached leaves was not reduced when the pH of the feeding solution containing 3-h-flooded [ABA] was increased from 6.7 to 7.1 Thus, the extent of the pH-mediated, shoot-sourced ABA redistribution was not sufficient to raise xylem [ABA] to physiologically active levels. Using a detached epidermis bioassay, significant non-ABA anti-transpirant activity was also detected in xylem sap collected at intervals during the first 24 h of soil flooding.

Direct micro-CT observation confirms the induction of embolism upon xylem cutting under tension

Science.gov (United States)

We used two different Synchrotron-based micro-CT facilities (SLS: Swiss Light Source, Villigen, Switzerland, and ALS: Advanced Light Source, Berkeley, CA USA) to test the excision artifact described by Wheeler et al. (2013). Specifically, we examined the impact of cutting xylem under tension and und...

A dendrochronology based fire history of Jeffry pine-mixed conifer forests in the Sierra San Pedro Martir, Mexico

Science.gov (United States)

Scott L. Stephens; Carl N. Skinner; Samantha J. Gill

2003-01-01

Conifer forests in northwestern Mexico have not experienced systematic fire suppression or logging, making them unique in western North America. Fire regimes of Pinus jeffreyi Grev. & Balf. mixed conifer forests in the Sierra San Pedro Martir, Baja California, Mexico, were determined by identifying 105 fire dates from 1034 fire scars in 105 specimens. Fires were...

Why Seedlings Die: Linking Carbon and Water Limitations to Mechanisms of Mortality During Establishment in Conifer Seedlings

Science.gov (United States)

Reinhardt, K.; Germino, M. J.; Kueppers, L. M.; Mitton, J.; Castanha, C.

2012-12-01

BACKGROUND Recent ecophysiological studies aimed at explaining adult tree mortality during drought have examined the carbon (C)-exhaustion compared to the hydraulic-failure hypotheses for death. Prolonged drought leads to durations of stomatal closure (and thus limited C gain), which could result in long periods of negative C balance and fatal reductions in whole-plant C reserves (i.e., available non-structural carbohydrates ["NSC"]). Alternatively, C reserves may not decrease much but could become increasingly inaccessible to sink tissues in long dry-periods due to impediments to translocation of photosynthate (e.g., through disruption of hydrostatic pressure flow in phloem). As C reserves decline or become inaccessible, continued maintenance respiration has been hypothesized to lead to exhaustion of NSC after extended durations of drought, especially in isohydric plant species. On the other hand, hydraulic failure (e.g., catastrophic xylem embolisms) during drought may be the proximate cause of death, occurring before true C starvation occurs. Few studies have investigated specifically the mechanism(s) of tree death, and no published studies that we know of have quantified changes in NSC during mortality. EXPERIMENTAL DESIGN AND HYPOTHESES We conducted two studies that investigated whole-tree and tissue-specific C relations (photosynthetic C gain, respiration, dry-mass gain, and NSC pools) in Pinus flexilis seedlings during the initial establishment phase, which is characterized by progressive drought during summer. We measured survival, growth and biomass allocation, and C-balance physiology (photosynthetic C-gain and chlorophyll fluorescence, respiration C-use, and NSC concentrations) from germination to mortality. We hypothesized that 1) stomatal and biochemical limitations to C gain would constrain seedling survival (through inadequate seasonal C-balance), as has been shown for conifer seedlings near alpine treeline; 2) hydraulic constraints (embolisms and

Microsatellite DNA as shared genetic markers among conifer species

Science.gov (United States)

Craig S. Echt; G.G. Vendramin; C.D. Nelson; P. Marquardt

1999-01-01

Polymerase chain reaction (PCR) primer pairs for 21 simple sequence repeat (SSR) loci in Pinus strobus L. and 6 in Pinus radiata D. Don. were evaluated to determine whether SSR marker amplification could be achieved in 10 other conifer species. Eighty percent of SSR primer pairs for (AC)n loci that were polymorphic in P. ...

Silvicultural Attempts to Induce Browse Resistance in Conifer Seedlings

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Bruce A. Kimball

2011-01-01

Full Text Available A multiyear study was conducted to determine if soil amendment combined with topical application of elemental sulfur could be employed to reduce deer browse damage to four conifer species. Fertilizer and sulfur were applied to conifer seedlings at seven sites near Corvallis, OR. Growth and browse damage data were collected for all seedlings over a period of 17 months. Additionally, foliar concentrations of monoterpenes and simple carbohydrates were assessed in western redcedar (Thuja plicata seedlings over a period of three years. Fertilization and sulfur treatments had a moderate impact on growth and no influence on browse damage or the chemical responses. Over the course of the study, browse damage diminished while foliar monoterpene concentrations increased in redcedar. It appears that silvicultural manipulation via sulfur application and/or soil amendment cannot accelerate or alter the ontogenetical changes that may naturally defend seedlings against mammalian herbivores. In a brief trial with captive deer, redcedar browse resistance was influenced by seedling maturation, but not monoterpene content. Other maturation effects may yield significant browse protection to young seedlings.

Mass spectrometric identification of isoforms of PR proteins in xylem sap of fungus-infected tomato

NARCIS (Netherlands)

Rep, Martijn; Dekker, Henk L.; Vossen, Jack H.; de Boer, Albert D.; Houterman, Petra M.; Speijer, Dave; Back, Jaap W.; de Koster, Chris G.; Cornelissen, Ben J. C.

2002-01-01

The protein content of tomato (Lycopersicon esculentum) xylem sap was found to change dramatically upon infection with the vascular wilt fungus Fusarium oxysporum. Peptide mass fingerprinting and mass spectrometric sequencing were used to identify the most abundant proteins appearing during

Upland log volumes and conifer establishment patterns in two northern, upland old-growth redwood forests, a brief synopsis

Science.gov (United States)

Daniel J. Porter; John O. Sawyer

2007-01-01

We characterized the volume, weight and top surface area of naturally fallen logs in an old-growth redwood forest, and quantified conifer recruit densities on these logs and on the surrounding forest floor. We report significantly greater conifer recruit densities on log substrates as compared to the forest floor. Log substrate availability was calculated on a per...

Restoring southern Ontario forests by managing succession in conifer plantations

Science.gov (United States)

William C. Parker; Ken A. Elliott; Daniel C. Dey; Eric Boysen

2008-01-01

Thinning and underplanting of conifer plantations to promote natural succession in southern Ontario's forests for restoration purposes was examined in a young red pine (Pinus resinosa Ait.) plantation. Eleven years after application of five thinning treatments, seedling diameter, height, and stem volume of planted white ash (Fraxinus...

Effects of dormancy progression and low-temperature response on changes in the sorbitol concentration in xylem sap of Japanese pear during winter season.

Science.gov (United States)

Ito, Akiko; Sugiura, Toshihiko; Sakamoto, Daisuke; Moriguchi, Takaya

2013-04-01

In order to elucidate which physiological event(s) are involved in the seasonal changes of carbohydrate dynamics during winter, we examined the effects of different low temperatures on the carbohydrate concentrations of Japanese pear (Pyrus pyrifolia (Burm.) Nakai). For four winter seasons, large increases in the sorbitol concentration of shoot xylem sap occurred during mid- to late December, possibly due to the endodormancy completion and low-temperature responses. When trees were kept at 15 °C from 3 November to 3 December in order to postpone the initiation and completion of chilling accumulation that would break endodormancy, sorbitol accumulation in xylem sap was always higher from trees with sufficient chilling accumulation than from trees that received insufficient chilling. However, an additional increase in xylem sap sorbitol occurred around late December in trees regardless of whether their chilling accumulation naturally progressed or was postponed. To examine different temperature effects more closely, we compared the carbohydrate concentrations of trees subjected to either 6 or 0 °C treatment. The sorbitol concentration in xylem sap tremendously increased at 0 °C treatment compared with 6 °C treatment. However, an additional increase in xylem sap sorbitol occurred at both the temperatures when sufficient chilling accumulated with a peak coinciding with the peak expression in shoots of the sorbitol transporter gene (PpSOT2). Interestingly, the total carbohydrate concentration of shoots tremendously increased with exposure to 0 °C compared with exposure to 6 °C, but was not affected by the amount of accumulated chilling. Instead, as chilling accumulated the ratio of sorbitol to total soluble sugars in shoots increased. We presumed that carbohydrates in the shoot tissues may be converted to sorbitol and loaded into the xylem sap so that the sorbitol accumulation patterns were synchronized with the progression of dormancy, whereas the total

Two tropical conifers show strong growth and water-use efficiency responses to altered CO2 concentration.

Science.gov (United States)

Dalling, James W; Cernusak, Lucas A; Winter, Klaus; Aranda, Jorge; Garcia, Milton; Virgo, Aurelio; Cheesman, Alexander W; Baresch, Andres; Jaramillo, Carlos; Turner, Benjamin L

2016-11-01

Conifers dominated wet lowland tropical forests 100 million years ago (MYA). With a few exceptions in the Podocarpaceae and Araucariaceae, conifers are now absent from this biome. This shift to angiosperm dominance also coincided with a large decline in atmospheric CO 2 concentration (c a ). We compared growth and physiological performance of two lowland tropical angiosperms and conifers at c a levels representing pre-industrial (280 ppm), ambient (400 ppm) and Eocene (800 ppm) conditions to explore how differences in c a affect the growth and water-use efficiency (WUE) of seedlings from these groups. Two conifers (Araucaria heterophylla and Podocarpus guatemalensis) and two angiosperm trees (Tabebuia rosea and Chrysophyllum cainito) were grown in climate-controlled glasshouses in Panama. Growth, photosynthetic rates, nutrient uptake, and nutrient use and water-use efficiencies were measured. Podocarpus seedlings showed a stronger (66 %) increase in relative growth rate with increasing c a relative to Araucaria (19 %) and the angiosperms (no growth enhancement). The response of Podocarpus is consistent with expectations for species with conservative growth traits and low mesophyll diffusion conductance. While previous work has shown limited stomatal response of conifers to c a , we found that the two conifers had significantly greater increases in leaf and whole-plant WUE than the angiosperms, reflecting increased photosynthetic rate and reduced stomatal conductance. Foliar nitrogen isotope ratios (δ 15 N) and soil nitrate concentrations indicated a preference in Podocarpus for ammonium over nitrate, which may impact nitrogen uptake relative to nitrate assimilators under high c a SIGNIFICANCE: Podocarps colonized tropical forests after angiosperms achieved dominance and are now restricted to infertile soils. Although limited to a single species, our data suggest that higher c a may have been favourable for podocarp colonization of tropical South America 60�

Northeastern conifer research: Multiple species and multiple values

Science.gov (United States)

Laura S. Kenefic; John C. Brissette; Richard W. Judd

2014-01-01

The northern conifer, or spruce-fir, forest of the northeastern USA and adjacent Canada has had a defining influence on the economy and culture of the region. The same can be said of the USDA Forest Service’s research in this forest, which began more than 100 years ago. Forest Service research has evolved since that time in response to changes in the needs and...

Magnetic resonance imaging of water ascent in embolized xylem vessels of grapevine stem segments

Science.gov (United States)

Mingtao Wang; Melvin T. Tyree; Roderick E. Wasylishen

2013-01-01

Temporal and spatial information about water refilling of embolized xylem vessels and the rate of water ascent in these vessels is critical for understanding embolism repair in intact living vascular plants. High-resolution 1H magnetic resonance imaging (MRI) experiments have been performed on embolized grapevine stem segments while they were...

Dynamic control of osmolality and ionic composition of the xylem sap in two mangrove species.

Science.gov (United States)

López-Portillo, Jorge; Ewers, Frank W; Méndez-Alonzo, Rodrigo; Paredes López, Claudia L; Angeles, Guillermo; Alarcón Jiménez, Ana Luisa; Lara-Domínguez, Ana Laura; Torres Barrera, María Del Carmen

2014-06-01

• Premise of the study: Xylem sap osmolality and salinity is a critical unresolved issue in plant function with impacts on transport efficiency, pressure gradients, and living cell turgor pressure, especially for halophytes such as mangrove trees.• Methods: We collected successive xylem vessel sap samples from stems and shoots of Avicennia germinans and Laguncularia racemosa using vacuum and pressure extraction and measured their osmolality. Following a series of extractions with the pressure chamber, we depressurized the shoot and pressurized again after various equilibration periods (minutes to hours) to test for dynamic control of osmolality. Transpiration and final sap osmolality were measured in shoots perfused with deionized water or different seawater dilutions.• Key results: For both species, the sap osmolality values of consecutive samples collected by vacuum extraction were stable and matched those of the initial samples extracted with the pressure chamber. Further extraction of samples with the pressure chamber decreased sap osmolality, suggesting reverse osmosis occurred. However, sap osmolalities increased when longer equilibration periods after sap extraction were allowed. Analysis of expressed sap with HPLC indicated a 1:1 relation between measured osmolality and the osmolality of the inorganic ions in the sap (mainly Na + , K + , and Cl - ), suggesting no contamination by organic compounds. In stems perfused with deionized water, the sap osmolality increased to mimic the native sap osmolality.• Conclusions: Xylem sap osmolality and ionic contents are dynamically adjusted by mangroves and may help modulate turgor pressure, hydraulic conductivity, and water potential, thus being important for mangrove physiology, survival, and distribution. © 2014 Botanical Society of America, Inc.

Soil Organic Carbon Storage and Stability in the Aspen-Conifer Ecotone in Montane Forests in Utah, USA

Directory of Open Access Journals (Sweden)

Mercedes Román Dobarco

2014-04-01

Full Text Available To assess the potential impact of conifer encroachment on soil organic carbon (SOC dynamics and storage in montane aspen-conifer forests from the interior western US, we sampled mineral soils (0–15 cm across the aspen-conifer ecotones in southern and northern Utah and quantified total SOC stocks, stable SOC (i.e., mineral-associated SOC (MoM, labile SOC (i.e., light fraction (LF, decomposable (CO2 release during long-term aerobic incubations and soluble SOC (hot water extractable organic carbon (HWEOC. Total SOC storage (47.0 ± 16.5 Mg C ha−1 and labile SOC as LF (14.0 ± 7.10 Mg C ha−1, SOC decomposability (cumulative released CO2-C of 5.6 ± 3.8 g C g−1 soil or HWEOC (0.6 ± 0.6 mg C g−1 soil did not differ substantially with vegetation type, although a slight increase in HWEOC was observed with increasing conifer in the overstory. There were statistically significant differences (p = 0.035 in stable MoM storage, which was higher under aspen (31.2 ± 15.1 Mg C ha−1 than under conifer (22.8 ± 9.0 Mg C ha−1, with intermediate values under mixed (25.7 ± 8.8 Mg C ha−1. Texture had the greatest impact on SOC distribution among labile and stable fractions, with increasing stabilization in MoM and decreasing bio-availability of SOC with increasing silt + clay content. Only at lower silt + clay contents (40%–70% could we discern the influence of vegetation on MoM content. This highlights the importance of chemical protection mechanisms for long-term C sequestration.

N. plumbaginifolia zeaxanthin epoxidase transgenic lines have unaltered baseline ABA accumulations in roots and xylem sap, but contrasting sensitivities of ABA accumulation to water deficit.

Science.gov (United States)

Borel, C; Audran, C; Frey, A; Marion-Poll, A; Tardieu, F; Simonneau, T

2001-03-01

A series of transgenic lines of Nicotiana plumbaginifolia with modified expression of zeaxanthin epoxidase gene (ZEP) provided contrasting ABA accumulation in roots and xylem sap. For mild water stress, concentration of ABA in the xylem sap ([ABA](xylem)) was clearly lower in plants underexpressing ZEP mRNA (complemented mutants and antisense transgenic lines) than in wild-type. In well-watered conditions, all lines presented similar [ABA](xylem) and similar ABA accumulation rates in detached roots. Plants could, therefore, be grown under normal light intensities and evaporative demand. Both ZEP mRNA abundance and ABA accumulation rate in roots increased with water deficit in all transgenic lines, except in complemented aba2-s1 mutants in which the ZEP gene was controlled by a constitutive promoter which does not respond to water deficit. These lines presented no change in root ABA content either with time or dehydration. The increase in ZEP mRNA abundance in roots with decreasing RWC was more pronounced in detached roots than in whole plants, suggesting a difference in mechanism. In all transgenic lines, a linear relationship was observed between predawn leaf water potential and [ABA](xylem), which could be reproduced in several experiments in the greenhouse and in the growth chamber. It is therefore possible to represent the effect of the transformation by a single parameter, thereby allowing the use of a quantitative approach to assist understanding of the behaviour of transgenic lines.

Intervessel connectivity and relationship with patterns of lateral water exchange within and between xylem sectors in seven xeric shrubs from the great Sahara desert.

Science.gov (United States)

Halis, Youcef; Mayouf, Rabah; Benhaddya, Mohamed Lamine; Belhamra, Mohamed

2013-03-01

The main objective of this study was to evaluate the role of intervessel contacts in determining the patterns of hydraulic integration both within and between xylem sectors. The degree of intervessel contacts and the lateral exchange capability within and between sectors were examined and correlated in different xeric shrubs. A dye injection method was used to detect the connections between vessels; an apoplastic dye was sucked through a known number of vessels and its distribution in the xylem network was followed. Hydraulic techniques were used to measure axial and tangential conductivity both within and between xylem sectors. The intra- and inter-sector integration indexes were then determined as the ratio of tangential to axial conductance. Species differed significantly in the degree of intervessel contacts, intra- and inter-sector integration index. In all cases, hydraulic integration was observed to be higher within sector than between sectors. From the correlation analyses, the intervessel contacts showed a very weak relationship with inter-sector integration index and a strong positive relationship with intra-sector integration index. Results suggested that (1) the factors affecting patterns of lateral flow within xylem sectors might be relatively different from those between sectors. (2) The degree of intervessel contacts was a major determinant of hydraulic integration within the same xylem sector. (3) Intervessel connectivity alone was a poor predictor of hydraulic integration between different sectors, implying a significant contribution of other anatomical, physiological and environmental factors in determining the patterns of integrated-sectored transport within woody stems.

A remotely sensed pigment index reveals photosynthetic phenology in evergreen conifers.

Science.gov (United States)

Gamon, John A; Huemmrich, K Fred; Wong, Christopher Y S; Ensminger, Ingo; Garrity, Steven; Hollinger, David Y; Noormets, Asko; Peñuelas, Josep

2016-11-15

In evergreen conifers, where the foliage amount changes little with season, accurate detection of the underlying "photosynthetic phenology" from satellite remote sensing has been difficult, presenting challenges for global models of ecosystem carbon uptake. Here, we report a close correspondence between seasonally changing foliar pigment levels, expressed as chlorophyll/carotenoid ratios, and evergreen photosynthetic activity, leading to a "chlorophyll/carotenoid index" (CCI) that tracks evergreen photosynthesis at multiple spatial scales. When calculated from NASA's Moderate Resolution Imaging Spectroradiometer satellite sensor, the CCI closely follows the seasonal patterns of daily gross primary productivity of evergreen conifer stands measured by eddy covariance. This discovery provides a way of monitoring evergreen photosynthetic activity from optical remote sensing, and indicates an important regulatory role for carotenoid pigments in evergreen photosynthesis. Improved methods of monitoring photosynthesis from space can improve our understanding of the global carbon budget in a warming world of changing vegetation phenology.

Physiological Effects of Smoke Exposure on Deciduous and Conifer Tree Species

International Nuclear Information System (INIS)

Calder, W.J.; Lifferth, G.; Clair, S.B.S.; Moritz, M.A.

2010-01-01

Smoke from forest fires can persist in the environment for weeks and while there is a substantial amount of literature examining the effects of smoke exposure on seed germination, the effects of smoke on leaf function are nearly un investigated. The objective of this study was to compare growth and primary and secondary metabolic responses of deciduous angiosperm and evergreen conifer tree species to short smoke exposure. Twenty minutes of smoke exposure resulted in a greater than 50% reduction in photosynthetic capacity in five of the six species we examined. Impairment of photosynthesis in response to smoke was a function of reductions in stomatal conductance and biochemical limitations. In general, deciduous angiosperm species showed a greater sensitivity than evergreen conifers. While there were significant decreases in photosynthesis and stomatal conductance, smoke had no significant effect on growth or secondary defense compound production in any of the tree species examined.

Physiological Effects of Smoke Exposure on Deciduous and Conifer Tree Species

Directory of Open Access Journals (Sweden)

W. John Calder

2010-01-01

Full Text Available Smoke from forest fires can persist in the environment for weeks and while there is a substantial amount of literature examining the effects of smoke exposure on seed germination, the effects of smoke on leaf function are nearly uninvestigated. The objective of this study was to compare growth and primary and secondary metabolic responses of deciduous angiosperm and evergreen conifer tree species to short smoke exposure. Twenty minutes of smoke exposure resulted in a greater than 50% reduction in photosynthetic capacity in five of the six species we examined. Impairment of photosynthesis in response to smoke was a function of reductions in stomatal conductance and biochemical limitations. In general, deciduous angiosperm species showed a greater sensitivity than evergreen conifers. While there were significant decreases in photosynthesis and stomatal conductance, smoke had no significant effect on growth or secondary defense compound production in any of the tree species examined.

Chemosystematics and diagenesis of terpenoids in fossil conifer species and sediment from the Eocene Zeitz formation, Saxony, Germany

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Otto, Angelika; Simoneit, Bernd R. T.

2001-10-01

The biomarker contents of three fossil conifer species (Athrotaxis couttsiae, Taxodium balticum, Pinus palaeostrobus) and the clay sediment from the Eocene Zeitz formation, Germany, have been analyzed by gas chromatography-mass spectrometry. Triterpenoids of the oleanane, ursane and lupane series and aliphatic wax lipids are the major compounds in the total extracts of the sediment indicating a major angiosperm input. In contrast, diterpenoids (abietanes, phenolic abietanes, pimaranes, isopimaranes, kauranes, phyllocladanes, totaranes) and lignin degradation products are predominant in the conifer fossil extracts. Polar diterpenoids (ferruginol and derivatives, dehydroabietic acid) are preserved as major compounds in the conifers, accompained by saturated and aromatic diterpenoid products. The extracts of the fossil conifer species show characteristic biomarker patterns and contain terpenoids of chemosystematic value. The terpenoid composition of the fossil conifers is similar to that of related modern species. Phenolic abietanes (ferruginol, 6,7-dehydroferruginol, hydroxyferruginols, sugiol) which are known from modern species of the Cupressaceae and Podocarpaceae are the major terpenoids in shoots of Athrotaxis couttsiae and a cone of Taxodium balticum (both Cupressaceae). Sesquiterpenoids characteristic for Cupressaceae (cuparene, α-cedrene) are also present in Athrotaxis. Abietane-type acids (dehydroabietic acid, abietic acid) and saturated abietanes [fichtelite, 13α(H)-fichtelite] predominate in the extracts of a Pinus palaeostrobus cone and phenolic abietanes are not detectable. A diagenetic pathway for the degradation of abietic acid is proposed based on the presence of abietane-type acids and a series of their presumed degradation products in the Pinus cone. The formation of diagenetic products from the phenolic abietanes is also discussed.

A comprehensive strategy for identifying long-distance mobile peptides in xylem sap.

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Okamoto, Satoru; Suzuki, Takamasa; Kawaguchi, Masayoshi; Higashiyama, Tetsuya; Matsubayashi, Yoshikatsu

2015-11-01

There is a growing awareness that secreted pemediate organ-to-organ communication in higher plants. Xylem sap peptidomics is an effective but challenging approach for identifying long-distance mobile peptides. In this study we developed a simple, gel-free purification system that combines o-chlorophenol extraction with HPLC separation. Using this system, we successfully identified seven oligopeptides from soybean xylem sap exudate that had one or more post-transcriptional modifications: glycosylation, sulfation and/or hydroxylation. RNA sequencing and quantitative PCR analyses showed that the peptide-encoding genes are expressed in multiple tissues. We further analyzed the long-distance translocation of four of the seven peptides using gene-encoding peptides with single amino acid substitutions, and identified these four peptides as potential root-to-shoot mobile oligopeptides. Promoter-GUS analysis showed that all four peptide-encoding genes were expressed in the inner tissues of the root endodermis. Moreover, we found that some of these peptide-encoding genes responded to biotic and/or abiotic factors. These results indicate that our purification system provides a comprehensive approach for effectively identifying endogenous small peptides and reinforce the concept that higher plants employ various peptides in root-to-shoot signaling. © 2015 The Authors The Plant Journal © 2015 John Wiley & Sons Ltd.

Differences in xylem and leaf hydraulic traits explain differences in drought tolerance among mature Amazon rainforest trees.

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Powell, Thomas L; Wheeler, James K; de Oliveira, Alex A R; da Costa, Antonio Carlos Lola; Saleska, Scott R; Meir, Patrick; Moorcroft, Paul R

2017-10-01

Considerable uncertainty surrounds the impacts of anthropogenic climate change on the composition and structure of Amazon forests. Building upon results from two large-scale ecosystem drought experiments in the eastern Brazilian Amazon that observed increases in mortality rates among some tree species but not others, in this study we investigate the physiological traits underpinning these differential demographic responses. Xylem pressure at 50% conductivity (xylem-P 50 ), leaf turgor loss point (TLP), cellular osmotic potential (π o ), and cellular bulk modulus of elasticity (ε), all traits mechanistically linked to drought tolerance, were measured on upper canopy branches and leaves of mature trees from selected species growing at the two drought experiment sites. Each species was placed a priori into one of four plant functional type (PFT) categories: drought-tolerant versus drought-intolerant based on observed mortality rates, and subdivided into early- versus late-successional based on wood density. We tested the hypotheses that the measured traits would be significantly different between the four PFTs and that they would be spatially conserved across the two experimental sites. Xylem-P 50 , TLP, and π o , but not ε, occurred at significantly higher water potentials for the drought-intolerant PFT compared to the drought-tolerant PFT; however, there were no significant differences between the early- and late-successional PFTs. These results suggest that these three traits are important for determining drought tolerance, and are largely independent of wood density-a trait commonly associated with successional status. Differences in these physiological traits that occurred between the drought-tolerant and drought-intolerant PFTs were conserved between the two research sites, even though they had different soil types and dry-season lengths. This more detailed understanding of how xylem and leaf hydraulic traits vary between co-occuring drought-tolerant and

Immunogold scanning electron microscopy can reveal the polysaccharide architecture of xylem cell walls

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Sun, Yuliang; Juzenas, Kevin

2017-01-01

Abstract Immunofluorescence microscopy (IFM) and immunogold transmission electron microscopy (TEM) are the two main techniques commonly used to detect polysaccharides in plant cell walls. Both are important in localizing cell wall polysaccharides, but both have major limitations, such as low resolution in IFM and restricted sample size for immunogold TEM. In this study, we have developed a robust technique that combines immunocytochemistry with scanning electron microscopy (SEM) to study cell wall polysaccharide architecture in xylem cells at high resolution over large areas of sample. Using multiple cell wall monoclonal antibodies (mAbs), this immunogold SEM technique reliably localized groups of hemicellulosic and pectic polysaccharides in the cell walls of five different xylem structures (vessel elements, fibers, axial and ray parenchyma cells, and tyloses). This demonstrates its important advantages over the other two methods for studying cell wall polysaccharide composition and distribution in these structures. In addition, it can show the three-dimensional distribution of a polysaccharide group in the vessel lateral wall and the polysaccharide components in the cell wall of developing tyloses. This technique, therefore, should be valuable for understanding the cell wall polysaccharide composition, architecture and functions of diverse cell types. PMID:28398585

Effects of environmental conditions on onset of xylem growth in Pinus sylvestris under drought.

Science.gov (United States)

Swidrak, Irene; Gruber, Andreas; Kofler, Werner; Oberhuber, Walter

2011-05-01

We determined the influence of environmental factors (air and soil temperature, precipitation, photoperiod) on onset of xylem growth in Scots pine (Pinus sylvestris L.) within a dry inner Alpine valley (750 m a.s.l., Tyrol, Austria) by repeatedly sampling micro-cores throughout 2007-10 at two sites (xeric and dry-mesic) at the start of the growing season. Temperature sums were calculated in degree-days (DD) ≥5 °C from 1 January and 20 March, i.e., spring equinox, to account for photoperiodic control of release from winter dormancy. Threshold temperatures at which xylogenesis had a 0.5 probability of being active were calculated by logistic regression. Onset of xylem growth, which was not significantly different between the xeric and dry-mesic sites, ranged from mid-April in 2007 to early May in 2008. Among most study years, statistically significant differences (Pdrought stress forces P. sylvestris to draw upon water reserves in the stem for enlargement of first tracheids after cambial resumption in spring. © The Author 2011. Published by Oxford University Press. All rights reserved.

Mixed-effects height–diameter models for ten conifers in the inland ...

African Journals Online (AJOL)

To demonstrate the utility of mixed-effects height–diameter models when conducting forest inventories, mixedeffects height–diameter models are presented for several commercially and ecologically important conifers in the inland Northwest of the USA. After obtaining height–diameter measurements from a plot/stand of ...

Mixed Conifer Forest Duff Consumption during Prescribed Fires: Tree Crown Impacts

NARCIS (Netherlands)

Hille, M.G.; Stephens, S.L.

2005-01-01

Fire suppression has produced large forest floor fuel loads in many coniferous forests in western North America. This study describes spatial patterns of duff consumption in a mixed-conifer forest in the north-central Sierra Nevada, California. Overstory crown coverage was correlated to spatial

Effect of 40 and 80 Years of Conifer Regrowth on Soil Microbial Activities and Community Structure in Subtropical Low Mountain Forests

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Ed-Haun Chang

2016-10-01

Full Text Available The effects of long-term reforestation on soil microbial communities and biomass are poorly understood. This study was conducted on two coniferous plantations: Cunninghamia konishii Hayata, planted 40 years ago (CONIF-40, and Calocedrus formosana (Florin Florin, planted 80 years ago (CONIF-80. An adjacent natural broadleaf forest (BROAD-Nat was used as a control. We determined microbial biomass C and N contents, enzyme activities, and community composition (via phospholipid fatty acid [PLFA] assessment. Both microbial biomass and PLFA content were higher in the summer than in the winter and differed among the forests in summer only. Total PLFA, total bacterial, gram-positive bacterial, gram-negative bacterial, and vesicular arbuscular mycorrhizal fungal contents followed the same pattern. Total fungal content and the ratios of fungi to bacteria and of gram-positive to gram-negative bacteria were highest in CONIF-40, with no difference between the other forests. Principal component analysis of PLFA contents revealed that CONIF-40 communities were distinct from those of CONIF-80 and BROAD-Nat. Our results suggest that vegetation replacement during reforestation exerts a prolonged impact on the soil microbial community. The understory broadleaf shrubs and trees established after coniferous plantation reforestation may balance out the effects of coniferous litter, contributing to bacterial recovery.

Tipping point of a conifer forest ecosystem under severe drought

Science.gov (United States)

Huang, Kaicheng; Yi, Chuixiang; Wu, Donghai; Zhou, Tao; Zhao, Xiang; Blanford, William J.; Wei, Suhua; Wu, Hao; Ling, Du; Li, Zheng

2015-02-01

Drought-induced tree mortality has recently received considerable attention. Questions have arisen over the necessary intensity and duration thresholds of droughts that are sufficient to trigger rapid forest declines. The values of such tipping points leading to forest declines due to drought are presently unknown. In this study, we have evaluated the potential relationship between the level of tree growth and concurrent drought conditions with data of the tree growth-related ring width index (RWI) of the two dominant conifer species (Pinus edulis and Pinus ponderosa) in the Southwestern United States (SWUS) and the meteorological drought-related standardized precipitation evapotranspiration index (SPEI). In this effort, we determined the binned averages of RWI and the 11 month SPEI within the month of July within each bin of 30 of RWI in the range of 0-3000. We found a significant correlation between the binned averages of RWI and SPEI at the regional-scale under dryer conditions. The tipping point of forest declines to drought is predicted by the regression model as SPEItp = -1.64 and RWItp = 0, that is, persistence of the water deficit (11 month) with intensity of -1.64 leading to negligible growth for the conifer species. When climate conditions are wetter, the correlation between the binned averages of RWI and SPEI is weaker which we believe is most likely due to soil water and atmospheric moisture levels no longer being the dominant factor limiting tree growth. We also illustrate a potential application of the derived tipping point (SPEItp = -1.64) through an examination of the 2002 extreme drought event in the SWUS conifer forest regions. Distinguished differences in remote-sensing based NDVI anomalies were found between the two regions partitioned by the derived tipping point.

Tipping point of a conifer forest ecosystem under severe drought

International Nuclear Information System (INIS)

Huang, Kaicheng; Zhou, Tao; Wu, Hao; Ling, Du; Li, Zheng; Yi, Chuixiang; Blanford, William J; Wei, Suhua; Wu, Donghai; Zhao, Xiang

2015-01-01

Drought-induced tree mortality has recently received considerable attention. Questions have arisen over the necessary intensity and duration thresholds of droughts that are sufficient to trigger rapid forest declines. The values of such tipping points leading to forest declines due to drought are presently unknown. In this study, we have evaluated the potential relationship between the level of tree growth and concurrent drought conditions with data of the tree growth-related ring width index (RWI) of the two dominant conifer species (Pinus edulis and Pinus ponderosa) in the Southwestern United States (SWUS) and the meteorological drought-related standardized precipitation evapotranspiration index (SPEI). In this effort, we determined the binned averages of RWI and the 11 month SPEI within the month of July within each bin of 30 of RWI in the range of 0–3000. We found a significant correlation between the binned averages of RWI and SPEI at the regional-scale under dryer conditions. The tipping point of forest declines to drought is predicted by the regression model as SPEI tp  = −1.64 and RWI tp  = 0, that is, persistence of the water deficit (11 month) with intensity of −1.64 leading to negligible growth for the conifer species. When climate conditions are wetter, the correlation between the binned averages of RWI and SPEI is weaker which we believe is most likely due to soil water and atmospheric moisture levels no longer being the dominant factor limiting tree growth. We also illustrate a potential application of the derived tipping point (SPEI tp  = −1.64) through an examination of the 2002 extreme drought event in the SWUS conifer forest regions. Distinguished differences in remote-sensing based NDVI anomalies were found between the two regions partitioned by the derived tipping point. (letter)

Twenty-five years of managing vegetation in conifer plantations in northern and central California: results, application, principles, and challenges

Science.gov (United States)

Philip M. McDonald; Gary O. Fiddler

2010-01-01

In the late 1970s, the outlook for conifer seedlings in new plantations in the Western United States was dismal&too many were dying or growing below the potential of the site. This situation was untenable, and a large study aimed at increasing the survival and growth of planted conifer seedlings was implemented. This was the National Administrative Study on...

Repression of BLADE-ON-PETIOLE genes by KNOX homeodomain protein BREVIPEDICELLUS is essential for differentiation of secondary xylem in Arabidopsis root.

Science.gov (United States)

Woerlen, Natalie; Allam, Gamalat; Popescu, Adina; Corrigan, Laura; Pautot, Véronique; Hepworth, Shelley R

2017-06-01

Repression of boundary genes by KNOTTED1-like homeodomain transcription factor BREVIPEDICELLUS promotes the differentiation of phase II secondary xylem in Arabidopsis roots. Plant growth and development relies on the activity of meristems. Boundaries are domains of restricted growth that separate forming organs and the meristem. Class I KNOX homeodomain transcription factors are important regulators of meristem maintenance. Members of this class including BREVIDICELLUS also called KNOTTED-LIKE FROM ARABIDOPSIS THALIANA1 (BP/KNAT1) fulfill this function in part by spatially regulating boundary genes. The vascular cambium is a lateral meristem that allows for radial expansion of organs during secondary growth. We show here that BP/KNAT1 repression of boundary genes plays a crucial role in root secondary growth. In particular, exclusion of BLADE-ON-PETIOLE1/2 (BOP1/2) and other members of this module from xylem is required for the differentiation of lignified fibers and vessels during the xylem expansion phase of root thickening. These data reveal a previously undiscovered role for boundary genes in the root and shed light on mechanisms controlling wood development in trees.

Black bear damage to northwestern conifers in California: a review

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Kenneth O. Fulgham; Dennis Hosack

2017-01-01

A total of 789 black bear damaged trees were investigate over a multi-year period on 14 different study sites chosen on lands of four participating timber companies. The sites ranged from 30 to 50 years of age. Four different conifer species were found to have black bear damage: coastal redwood (Sequoia sempervirens (D. Don) Endl.), Douglas-fir (...

BRANCH JUNCTIONS AND THE FLOW OF WATER THROUGH XYLEM IN DOUGLAS-FIR AND PONDEROSA PINE STEMS

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Water flowing through the xylem of most plants from the roots to the leaves must pass through junctions where branches have developed from the main stem. These junctions have been studied as both flow constrictions and components of a hydraulic segmentation mechanism to protect ...

Stem girdling affects the quantity of CO2 transported in xylem as well as CO2 efflux from soil.

Science.gov (United States)

Bloemen, Jasper; Agneessens, Laura; Van Meulebroek, Lieven; Aubrey, Doug P; McGuire, Mary Anne; Teskey, Robert O; Steppe, Kathy

2014-02-01

There is recent clear evidence that an important fraction of root-respired CO2 is transported upward in the transpiration stream in tree stems rather than fluxing to the soil. In this study, we aimed to quantify the contribution of root-respired CO2 to both soil CO2 efflux and xylem CO2 transport by manipulating the autotrophic component of belowground respiration. We compared soil CO2 efflux and the flux of root-respired CO2 transported in the transpiration stream in girdled and nongirdled 9-yr-old oak trees (Quercus robur) to assess the impact of a change in the autotrophic component of belowground respiration on both CO2 fluxes. Stem girdling decreased xylem CO2 concentration, indicating that belowground respiration contributes to the aboveground transport of internal CO2 . Girdling also decreased soil CO2 efflux. These results confirmed that root respiration contributes to xylem CO2 transport and that failure to account for this flux results in inaccurate estimates of belowground respiration when efflux-based methods are used. This research adds to the growing body of evidence that efflux-based measurements of belowground respiration underestimate autotrophic contributions. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

Comparative Structural Dynamics of the Janj Mixed Old-Growth Mountain Forest in Bosnia and Herzegovina: Are Conifers in a Long-Term Decline?

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Srdjan Keren

2014-06-01

Full Text Available Regression of conifers in European mixed old-growth mountain forests has been observed for a long period and studied from different aspects. Old-growth (OG forests in Bosnia and Herzegovina (BiH have not experienced heavy air pollution and chronic overbrowsing that have affected many other European OG forests, while climatic and anthropogenic disturbances have been well documented. We analysed stand structure in the Janj OG forest, compared it with inventories of Lom and Perucica OG forests (BiH and with earlier inventories of the same reserves. At present, OG forest Janj is characterized by a high growing stock (1215 m3∙ha−1. This is due to good site quality, prevalence of conifers (84% and dominant endogenous processes in recent decades. In all three OG forests, indicators of structural change exhibited progression of European beech over time. Historical evidence revealed the occurrence of warm summers and droughts followed by bark beetle outbreaks in the 1920s, 1940s and early 1950s, which in turn influenced a marked conifer decline. It seems likely that repeated canopy opening released waves of European beech regeneration. These stand structural changes have delayed the rejuvenation of conifers and can help explain the early observations of conifer decline.

A long-term assessment of the variability in winter use of dense conifer cover by female white-tailed deer.

Directory of Open Access Journals (Sweden)

Glenn D Delgiudice

Full Text Available Long-term studies allow capture of a wide breadth of environmental variability and a broader context within which to maximize our understanding of relationships to specific aspects of wildlife behavior. The goal of our study was to improve our understanding of the biological value of dense conifer cover to deer on winter range relative to snow depth and ambient temperature.We examined variation among deer in their use of dense conifer cover during a 12-year study period as potentially influenced by winter severity and cover availability. Female deer were fitted with a mixture of very high frequency (VHF, n = 267 and Global Positioning System (GPS, n = 24 collars for monitoring use of specific cover types at the population and individual levels, respectively. We developed habitat composites for four study sites. We fit multinomial response models to VHF (daytime data to describe population-level use patterns as a function of snow depth, ambient temperature, and cover availability. To develop alternative hypotheses regarding expected spatio-temporal patterns in the use of dense conifer cover, we considered two sets of competing sub-hypotheses. The first set addressed whether or not dense conifer cover was limiting on the four study sites. The second set considered four alternative sub-hypotheses regarding the potential influence of snow depth and ambient temperature on space use patterns. Deer use of dense conifer cover increased the most with increasing snow depth and most abruptly on the two sites where it was most available, suggestive of an energy conservation strategy. Deer use of dense cover decreased the most with decreasing temperatures on the sites where it was most available. At all four sites deer made greater daytime use (55 to >80% probability of use of open vegetation types at the lowest daily minimum temperatures indicating the importance of thermal benefits afforded from increased exposure to solar radiation. Date

Conifer Decline and Mortality in Siberia

Science.gov (United States)

Kharuk, V.; Im, S.; Ranson, K.

2015-12-01

"Dark needle conifer" (DNC: Abies sibirica, Pinus sibirica and Picea obovata) decline and mortality increase were documented in Russia during recent decades. Here we analyzed causes and scale of Siberian pine and fir mortality in Altai-Sayan and Baikal Lake Regions and West Siberian Plane based on in situdata and remote sensing (QuickBird, Landsat, GRACE). Geographically, mortality began on the margins of the DNC range (i.e., within the forest-steppe and conifer-broadleaf ecotones) and on terrain features with maximal water stress risk (narrow-shaped hilltops, convex steep south facing slopes, shallow well-drained soils). Within ridges, mortality occurred mainly along mountain passes, where stands faced drying winds. Regularly mortality was observed to decrease with elevation increase with the exception of Baikal Lake Mountains, where it was minimal near the lake shore and increased with elevation (up to about 1000 m a.s.l.). Siberian pine and fir mortality followed a drying trend with consecutive droughts since the 1980s. Dendrochronology analysis showed that mortality was correlated with vapor pressure deficit increase, drought index, soil moisture decrease and occurrence of late frosts. In Baikal region Siberian pine mortality correlated with Baikal watershed meteorological variables. An impact of previous year climate conditions on the current growth was found (r2 = 0.6). Thus, water-stressed trees became sensitive to bark beetles and fungi impact (including Polygraphus proximus and Heterobasidion annosum). At present, an increase in mortality is observed within the majority of DNC range. Results obtained also showed a primary role of water stress in that phenomenon with a secondary role of bark beetles and fungi attacks. In future climate with increased drought severity and frequency Siberian pine and fir will partly disappear from its current range, and will be substituted by drought-tolerant species (e.g., Pinus silvestris, Larix sibirica).

Magnetoimpedance effects in a CoNiFe nanowire array

Energy Technology Data Exchange (ETDEWEB)

Atalay, S., E-mail: selcuk.atalay@inonu.edu.tr [Inonu University, Science and Arts Faculty, Physics Department, Malatya (Turkey); Kaya, H.; Atalay, F.E.; Aydogmus, E. [Inonu University, Science and Arts Faculty, Physics Department, Malatya (Turkey)

2013-06-05

Highlights: ► CoNiFe nanowires were produced by electrodeposition method. ► Magnetoimpedance effect of nanowires arrays were investigated. ► Single peak behaviour was observed in the magnetoimpedance curve. ► Nanowire arrays exhibit uniaxial magnetic anisotropy along the wire axis. -- Abstract: This report describes the growth of CoNiFe nanowires into highly ordered porous anodic alumina oxide (AAO) templates by DC electrodeposition at a pH value of 2.6. Scanning electron microscopy (SEM) observations revealed that the wires have diameters of approximately 270–290 nm and a length of 25 μm. The energy dispersive X-ray (EDX) analysis indicated that the composition of the nanowires is Co{sub 12}Ni{sub 64}Fe{sub 24}. Electrical contacts were created on both sides of the nanowire array, and their magnetoimpedance (MI) properties were investigated. The impedance value was initially 1.2 ohm at low frequency and increased to approximately 1000 ohm for a 33-MHz driving current frequency under no applied magnetic field. All the MI curves exhibited single peak behaviour due to the high shape anisotropy. The maximum MI change at the 33-MHz driving current frequency was 2.72%. The maximum resistance change was 5.4% at 33 MHz.

Kinetics of tracheid development explain conifer tree-ring structure.

Science.gov (United States)

Cuny, Henri E; Rathgeber, Cyrille B K; Frank, David; Fonti, Patrick; Fournier, Meriem

2014-09-01

Conifer tree rings are generally composed of large, thin-walled cells of light earlywood followed by narrow, thick-walled cells of dense latewood. Yet, how wood formation processes and the associated kinetics create this typical pattern remains poorly understood. We monitored tree-ring formation weekly over 3 yr in 45 trees of three conifer species in France. Data were used to model cell development kinetics, and to attribute the relative importance of the duration and rate of cell enlargement and cell wall deposition on tree-ring structure. Cell enlargement duration contributed to 75% of changes in cell diameter along the tree rings. Remarkably, the amount of wall material per cell was quite constant along the rings. Consequently, and in contrast with widespread belief, changes in cell wall thickness were not principally attributed to the duration and rate of wall deposition (33%), but rather to the changes in cell size (67%). Cell enlargement duration, as the main driver of cell size and wall thickness, contributed to 56% of wood density variation along the rings. This mechanistic framework now forms the basis for unraveling how environmental stresses trigger deviations (e.g. false rings) from the normal tree-ring structure. © 2014 The Authors. New Phytologist © 2014 New Phytologist Trust.

Elevated temperature and CO2 concentration effects on xylem anatomy of Scots pine

International Nuclear Information System (INIS)

Kilpelainen, A.; Gerendiain, A.Z.; Luostarinen, K.; Peltola, H.; Kellomaki, S.

2007-01-01

The effects of carbon dioxide (CO 2 ) concentrations and elevated temperatures on the xylem anatomy of 20-year old Scots pine trees were investigated. The experiment was conducted in 16 chambers containing 4 trees each with a factorial combination of both ambient and elevated CO 2 concentrations and 2 different temperature regimes. CO 2 concentrations were doubled with a corresponding increase of between 2 and 6 degrees C according to each season over a period of 6 years. The study showed that elevated CO 2 concentrations increased the ring width in 4 of the 6 analyzed treatment years. Earlywood width increased during the first 2 years of the experiment, while latewood width increased during the third year of the study. The study also showed that the tracheid walls in both the latewood and earlywood samples were thicker when either temperature levels or CO 2 levels were increased. It was noted that combined CO 2 and temperature elevations resulted in thinner tracheid walls. However, latewood tracheid lumen diameters were larger in all CO 2 and temperature treatments than trees grown in ambient conditions. It was concluded that xylem anatomy was impacted more by increases in temperature than by elevated CO 2 concentrations. 48 refs., 2 tabs., 6 figs

Exogenous GA3 Application Enhances Xylem Development and Induces the Expression of Secondary Wall Biosynthesis Related Genes in Betula platyphylla

Directory of Open Access Journals (Sweden)

Huiyan Guo

2015-09-01

Full Text Available Gibberellin (GA is a key signal molecule inducing differentiation of tracheary elements, fibers, and xylogenesis. However the molecular mechanisms underlying the effect of GA on xylem elongation and secondary wall development in tree species remain to be determined. In this study, Betula platyphylla (birch seeds were treated with 300 ppm GA3 and/or 300 ppm paclobutrazol (PAC, seed germination was recorded, and transverse sections of hypocotyls were stained with toluidine blue; the two-month-old seedlings were treated with 50 μM GA3 and/or 50 μM PAC, transverse sections of seedling stems were stained using phloroglucinol–HCl, and secondary wall biosynthesis related genes expression was analyzed by real-time quantitative PCR. Results indicated that germination percentage, energy and time of seeds, hypocotyl height and seedling fresh weight were enhanced by GA3, and reduced by PAC; the xylem development was wider in GA3-treated plants than in the control; the expression of NAC and MYB transcription factors, CESA, PAL, and GA oxidase was up-regulated during GA3 treatment, suggesting their role in GA3-induced xylem development in the birch. Our results suggest that GA3 induces the expression of secondary wall biosynthesis related genes to trigger xylogenesis in the birch plants.

Long-term demographic trends in a fire-suppressed mixed-conifer forest

Science.gov (United States)

Carrie R. Levine; Flora Krivak-Tetley; Natalie S. van Doorn; Jolie-Anne S. Ansley; John J. Battles

2016-01-01

In the western United States, forests are experiencing novel environmental conditions related to a changing climate and a suppression of the historical fire regime. Mixed-conifer forests, considered resilient to disturbance due to their heterogeneity in structure and composition, appear to be shifting to a more homogeneous state, but the timescale of these shifts is...

Spatial distribution of xylem embolisms in the stems of Pinus thunbergii at the threshold of fatal drought stress.

Science.gov (United States)

Umebayashi, Toshihiro; Morita, Toshimitsu; Utsumi, Yasuhiro; Kusumoto, Dai; Yasuda, Yuko; Haishi, Tomoyuki; Fukuda, Kenji

2016-10-01

Although previous studies have suggested that branch dieback and whole-plant death due to drought stress occur at 50-88% loss of stem hydraulic conductivity (P 50 and P 88 , respectively), the dynamics of catastrophic failure in the water-conducting pathways in whole plants subjected to drought remain poorly understood. We examined the dynamics of drought stress tolerance in 3-year-old Japanese black pine (Pinus thunbergii Parl.). We nondestructively monitored (i) the spatial distribution of drought-induced embolisms in the stem at greater than P 50 and (ii) recovery from embolisms following rehydration. Stem water distributions were visualized by cryo-scanning electron microscopy. The percentages of both embolized area and loss of hydraulic conductivity showed similar patterns of increase, although the water loss in xylem increased markedly at -5.0 MPa or less. One seedling that had reached 72% loss of the water-conducting area survived and the xylem water potential recovered to -0.3 MPa. We concluded that Japanese black pines may need to maintain water-filled tracheids within earlywood of the current-year xylem under natural conditions to avoid disconnection of water movement between the stem and the tops of branches. It is necessary to determine the spatial distribution of embolisms around the point of the lethal threshold to gain an improved understanding of plant survival under conditions of drought. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Trends in Snag Populations in Drought-Stressed Mixed-Conifer and Ponderosa Pine Forests (1997–2007

Directory of Open Access Journals (Sweden)

Joseph L. Ganey

2012-01-01

Full Text Available Snags provide important biological legacies, resources for numerous species of native wildlife, and contribute to decay dynamics and ecological processes in forested ecosystems. We monitored trends in snag populations from 1997 to 2007 in drought-stressed mixed-conifer and ponderosa pine (Pinus ponderosa Dougl. ex Laws forests, northern Arizona. Median snag density increased by 75 and 90% in mixed-conifer and ponderosa pine forests, respectively, over this time period. Increased snag density was driven primarily by a large pulse in drought-mediated tree mortality from 2002 to 2007, following a smaller pulse from 1997 to 2002. Decay-class composition and size-class composition of snag populations changed in both forest types, and species composition changed in mixed-conifer forest. Increases in snag abundance may benefit some species of native wildlife in the short-term by providing increased foraging and nesting resources, but these increases may be unsustainable in the long term. Observed changes in snag recruitment and fall rates during the study illustrate the difficulty involved in modeling dynamics of those populations in an era of climate change and changing land management practices.

Physical characteristics of shrub and conifer fuels for fire behavior models

Science.gov (United States)

Jonathan R. Gallacher; Thomas H. Fletcher; Victoria Lansinger; Sydney Hansen; Taylor Ellsworth; David R. Weise

2017-01-01

The physical properties and dimensions of foliage are necessary inputs for some fire spread models. Currently, almost no data exist on these plant characteristics to fill this need. In this report, we measured the physical properties and dimensions of the foliage from 10 live shrub and conifer fuels throughout a 1-year period. We developed models to predict relative...

78 FR 77649 - Notification of Proposed Production Activity, Xylem Water Systems USA LLC, Subzone 37D...

Science.gov (United States)

2013-12-24

... inputs noted below and in the existing scope of authority. Customs duties also could possibly be deferred... December 2, 2013. Xylem already has authority to produce centrifugal pumps, submersible pumps, and related... components to the scope of authority. Pursuant to 15 CFR 400.14(b), FTZ activity would be limited to the...

Late Cenozoic climate and the phylogenetic structure of regional conifer floras worldwide

NARCIS (Netherlands)

Eiserhardt, W.L.; Borchsenius, F.; Sandel, B.; Kissling, W.D.; Svenning, J.-C.

2015-01-01

Aim Using conifers as a model system, we aim to test four hypotheses. H1: the processes that shape the phylogenetic structure of regional species assemblages depend on climate. H2: apparent effects of current climate can be equally well explained by past climate. H3: strong Quaternary climate

Using object-based image analysis to conduct high-resolution conifer extraction at regional spatial scales

Science.gov (United States)

Coates, Peter S.; Gustafson, K. Benjamin; Roth, Cali L.; Chenaille, Michael P.; Ricca, Mark A.; Mauch, Kimberly; Sanchez-Chopitea, Erika; Kroger, Travis J.; Perry, William M.; Casazza, Michael L.

2017-08-10

The distribution and abundance of pinyon (Pinus monophylla) and juniper (Juniperus osteosperma, J. occidentalis) trees (hereinafter, "pinyon-juniper") in sagebrush (Artemisia spp.) ecosystems of the Great Basin in the Western United States has increased substantially since the late 1800s. Distributional expansion and infill of pinyon-juniper into sagebrush ecosystems threatens the ecological function and economic viability of these ecosystems within the Great Basin, and is now a major contemporary challenge facing land and wildlife managers. Particularly, pinyon-juniper encroachment into intact sagebrush ecosystems has been identified as a primary threat facing populations of greater sage-grouse (Centrocercus urophasianus; hereinafter, "sage-grouse"), which is a sagebrush obligate species. Even seemingly innocuous scatterings of isolated pinyon-juniper in an otherwise intact sagebrush landscape can negatively affect survival and reproduction of sage-grouse. Therefore, accurate and high-resolution maps of pinyon-juniper distribution and abundance (indexed by canopy cover) across broad geographic extents would help guide land management decisions that better target areas for pinyon-juniper removal projects (for example, fuel reduction, habitat improvement for sage-grouse, and other sagebrush species) and facilitate science that further quantifies ecological effects of pinyon-juniper encroachment on sage-grouse populations and sagebrush ecosystem processes. Hence, we mapped pinyon-juniper (referred to as conifers for actual mapping) at a 1 × 1-meter (m) high resolution across the entire range of previously mapped sage-grouse habitat in Nevada and northeastern California.We used digital orthophoto quad tiles from National Agriculture Imagery Program (2010, 2013) as base imagery, and then classified conifers using automated feature extraction methodology with the program Feature Analyst™. This method relies on machine learning algorithms that extract features from

Height development of shade-tolerant conifer saplings in multiaged Acadian forest stands

Science.gov (United States)

Andrew R. Moores; Robert S. Seymour; Laura S. Kenefic

2007-01-01

Understory growth dynamics of northern conifer species were studied in four stands managed under multiaged silvicultural systems in eastern Maine. Height growth of Picea rubens Sarg., Abies balsamea (L.) Mill., and Tsuga canadensis (L.) Carr. saplings between 0.5 and 6.0 m in height was related to the proportion...

Potassium co-transport and antiport during the uptake of sucrose and glutamic acid from the xylem vessels

NARCIS (Netherlands)

Bel, A.J.E. van; Erven, A.J. van

Perfusion experiments with excised internodes of tomato (Lycopersicon esculentum cv Moneymaker) showed that the uptake of glutamic acid and sucrose from the xylem vessels is accompanied with coupled proton co-transport and potassium antiport at low pH (<5.5). At high pH (5.5) both proton and

Apical control of xylem formation in the pine stem. II. Responses of differentiating tracheids

Directory of Open Access Journals (Sweden)

Jarosław Porandowski

2014-01-01

Full Text Available The effect of auxin supplied to the main stem of 5-year-old Pinus silvestris trees during various periods after decapitation upon differentiation of the secondary xylem tracheids was investigated. The results revealed the complexity of auxin involvement in the regulatory system of tracheid differentiation of secondary xylem. It is manifested both as the inductive effect to which the cells respond in the meristematic phase and in the continuous control during the consecutive stages of radial growth and maturation. A lack of auxin during the meristematic phase resulted in smaller cell diameters and reduced the daily rate of cell wall deposition even though these cells progressively grew and matured in the presence of auxin. The intensity of these two processes increased and the cells deposited thicker walls when auxin was supplied during all stages of tracheid differentiation even though the period of maturation decreased. Under these conditions tracheids of compression wood type differentiated. Continuous availability of auxin causes earlier termination of tracheid maturation while lack of auxin results in a delay of autolysis of protoplasts. In this case auxin probably functions in a system specifying information concerning the position of the cells in respect to the cambial layer.

Elevated temperature and CO{sub 2} concentration effects on xylem anatomy of Scots pine

Energy Technology Data Exchange (ETDEWEB)

Kilpelainen, A.; Gerendiain, A.Z.; Luostarinen, K.; Peltola, H.; Kellomaki, S. [Joensuu Univ., Joensuu (Finland). Faculty of Forestry

2007-09-15

The effects of carbon dioxide (CO{sub 2}) concentrations and elevated temperatures on the xylem anatomy of 20-year old Scots pine trees were investigated. The experiment was conducted in 16 chambers containing 4 trees each with a factorial combination of both ambient and elevated CO{sub 2} concentrations and 2 different temperature regimes. CO{sub 2} concentrations were doubled with a corresponding increase of between 2 and 6 degrees C according to each season over a period of 6 years. The study showed that elevated CO{sub 2} concentrations increased the ring width in 4 of the 6 analyzed treatment years. Earlywood width increased during the first 2 years of the experiment, while latewood width increased during the third year of the study. The study also showed that the tracheid walls in both the latewood and earlywood samples were thicker when either temperature levels or CO{sub 2} levels were increased. It was noted that combined CO{sub 2} and temperature elevations resulted in thinner tracheid walls. However, latewood tracheid lumen diameters were larger in all CO{sub 2} and temperature treatments than trees grown in ambient conditions. It was concluded that xylem anatomy was impacted more by increases in temperature than by elevated CO{sub 2} concentrations. 48 refs., 2 tabs., 6 figs.

Structure of the secondary xylem of Aniba Aubl. species from the Brazilian Amazon

Directory of Open Access Journals (Sweden)

Cláudia Viana Urbinati

2014-09-01

Full Text Available The aim of this study was to characterize the wood of Aniba species from the Brazilian Amazon, on the basis of specimens in the wood collection of the Herbarium of the Museu Paraense Emílio Goeldi, in the city of Belém, Brazil. The species were found to present a homogeneous structure in the secondary xylem, as defined by the location of oil cells; the presence of tyloses and crystals; and singularities of the radial and axial parenchyma.

Effect of Sugar Maple Root Exudate on Seedlings of Northern Conifer Species

Science.gov (United States)

Carl H. Tubbs

1976-01-01

It has been shows that a root exudate of sugar maple reduces the growth of yellow birch. A laboratory test indicated that the growth of northern conifers is also reduced in sugar maple root exudate. Allelopathy may play an important role in survival of species on sites where sugar maple is abundant.

Comparing algorithms for estimating foliar biomass of conifers in the Pacific Northwest

Science.gov (United States)

Crystal L. Raymond; Donald. McKenzie

2013-01-01

Accurate estimates of foliar biomass (FB) are important for quantifying carbon storage in forest ecosystems, but FB is not always reported in regional or national inventories. Foliar biomass also drives key ecological processes in ecosystem models. Published algorithms for estimating FB in conifer species of the Pacific Northwest can yield signifi cantly different...

Integration and macroevolutionary patterns in the pollination biology of conifers.

Science.gov (United States)

Leslie, Andrew B; Beaulieu, Jeremy M; Crane, Peter R; Knopf, Patrick; Donoghue, Michael J

2015-06-01

Integration influences patterns of trait evolution, but the relationship between these patterns and the degree of trait integration is not well understood. To explore this further, we study a specialized pollination mechanism in conifers whose traits are linked through function but not development. This mechanism depends on interactions among three characters: pollen that is buoyant, ovules that face downward at pollination, and the production of a liquid droplet that buoyant grains float through to enter the ovule. We use a well-sampled phylogeny of conifers to test correlated evolution among these characters and specific sequences of character change. Using likelihood models of character evolution, we find that pollen morphology and ovule characters evolve in a concerted manner, where the flotation mechanism breaks down irreversibly following changes in orientation or drop production. The breakdown of this functional constraint, which may be facilitated by the lack of developmental integration among the constituent traits, is associated with increased trait variation and more diverse pollination strategies. Although this functional "release" increases diversity in some ways, the irreversible way in which the flotation mechanism is lost may eventually result in its complete disappearance from seed plant reproductive biology. © 2015 The Author(s). Evolution © 2015 The Society for the Study of Evolution.

Avoiding transport bottlenecks in an expanding root system: xylem vessel development in fibrous and pioneer roots under field conditions.

Science.gov (United States)

Bagniewska-Zadworna, Agnieszka; Byczyk, Julia; Eissenstat, David M; Oleksyn, Jacek; Zadworny, Marcin

2012-09-01

Root systems develop to effectively absorb water and nutrients and to rapidly transport these materials to the transpiring shoot. In woody plants, roots can be born with different functions: fibrous roots are primarily used for water and nutrient absorption, whereas pioneer roots have a greater role in transport. Because pioneer roots extend rapidly in the soil and typically quickly produce fibrous roots, they need to develop transport capacity rapidly so as to avoid becoming a bottleneck to the absorbed water of the developing fibrous roots and, as we hypothesized, immediately activate a specific type of autophagy at a precise time of their development. Using microscopy techniques, we monitored xylem development in Populus trichocarpa roots in the first 7 d after emergence under field conditions. Newly formed pioneer roots contained more primary xylem poles and had larger diameter tracheary elements than fibrous roots. While xylogenesis started later in pioneer roots than in fibrous, it was completed at the same time, resulting in functional vessels on the third to fourth day following root emergence. Programmed cell death was responsible for creating the water conducting capacity of xylem. Although the early xylogenesis processes were similar in fibrous and pioneer roots, secondary vascular development proceeded much more rapidly in pioneer roots. Compared to fibrous roots, rapid development of transport capacity in pioneer roots is not primarily caused by accelerated xylogenesis but by larger and more numerous tracheary elements and by rapid initiation of secondary growth.

Regeneration patterns of a long-lived dominant conifer and the effects of logging in southern South America

Science.gov (United States)

Souza, Alexandre F.; Forgiarini, Cristiane; Longhi, Solon Jonas; Brena, Doádi Antônio

2008-09-01

The regeneration ecology of the long-lived conifer Araucaria angustifolia was studied in São Francisco de Paula, southern Brazil. We evaluated the expectations that: (i) size distribution of populations of Araucaria angustifolia, a large conifer that dominates southern Brazil's mixed forests, is left-skewed in old-growth forests but right-skewed in logged forests, indicating chronic recruitment failure in the first kind of habitat as well as a recruitment pulse in the second; (ii) seedlings and juveniles are found under more open-canopy microsites than would be expected by chance; and (iii) reproductive females would be aggregated at the coarse spatial scales in which past massive recruitment events are expected to have occurred, and young plants would be spatially associated with females due to the prevalence of vertebrate and large-bird seed dispersers. Data were collected in the threatened mixed conifer-hardwood forests in southern Brazil in ten 1-ha plots and one 0.25-ha plot that was hit by a small tornado in 2003. Five of these plots corresponded to unlogged old-growth forests, three to forests where A. angustifolia was selectively logged ca. 60 years ago and two to forests selectively logged ca. 20 years ago. For the first time, ontogenetic life stages of this important conifer are identified and described. The first and second expectations were fulfilled, and the third was partially fulfilled, since seedlings and juveniles were hardly ever associated with reproductive females. These results confirm the generalization of the current conceptual model of emergent long-lived pioneer regeneration to Araucaria angustifolia and associate its regeneration niche to the occupation of large-scale disturbances with long return times.

Cytokinin profiles in the conifer tree Abies nordmanniana

DEFF Research Database (Denmark)

Rasmussen, Hanne Nina; Veierskov, Bjarke; Hansen-Møller, Jens

2009-01-01

in the crown and root system were sampled destructively in 4- and 6-year-old trees and analyzed for a range of cytokinins by LC-MS/MS. No seasonal patterns were detected in the root samples, and a major portion of cytokinin was in conjugated forms. Dramatic and consistent seasonal changes occurred in the crown......Abstract  Conifer trees are routinely manipulated hormonally to increase flowering, branching, or adjust crown shape for production purposes. This survey of internal cytokinin levels provides a background for such treatments in Abies nordmanniana, a tree of great economic interest. Reference points...

Overexpression of the cytosolic cytokinin oxidase/dehydrogenase (CKX7) from Arabidopsis causes specific changes in root growth and xylem differentiation

Czech Academy of Sciences Publication Activity Database

Kollmer, I.; Novák, Ondřej; Strnad, Miroslav; Schmülling, T.; Werner, T.

2014-01-01

Roč. 78, č. 3 (2014), s. 359-371 ISSN 0960-7412 Institutional support: RVO:61389030 Keywords : xylem differentiation * Arabidopsis thaliana * cytokinin oxidase/dehydrogenase Subject RIV: ED - Physiology Impact factor: 5.972, year: 2014

Semiochemical sabotage: behavioral chemicals for protection of western conifers from bark beetles

Science.gov (United States)

Nancy. E. Gillette; A. Steve Munson

2009-01-01

The discovery and elucidation of volatile behavioral chemicals used by bark beetles to locate hosts and mates has revealed a rich potential for humans to sabotage beetle host-finding and reproduction. Here, we present a description of currently available semiochemical methods for use in monitoring and controlling bark beetle pests in western conifer forests. Delivery...

Fire-induced wounding elicits changes in the wood anatomy of North American conifers

Science.gov (United States)

Estelle Arbellay; Markus Stoffel; Elaine K. Sutherland; Kevin T. Smith; Donald A. Falk

2013-01-01

Fire is a major disturbance agent in North American forests. Fires injure trees when heat transfer through the bark partially kills the cambium and the compartmentalization process results in a fire scar. Dendrochronologists use these scars in the xylem to reconstruct fire regimes. However, little information exists on the wood anatomy of fire scars. Consequently, this...

Normalizing gene expression by quantitative PCR during somatic embryogenesis in two representative conifer species: Pinus pinaster and Picea abies.

Science.gov (United States)

de Vega-Bartol, José J; Santos, Raquen Raissa; Simões, Marta; Miguel, Célia M

2013-05-01

Suitable internal control genes to normalize qPCR data from different stages of embryo development and germination were identified in two representative conifer species. Clonal propagation by somatic embryogenesis has a great application potentiality in conifers. Quantitative PCR (qPCR) is widely used for gene expression analysis during somatic embryogenesis and embryo germination. No single reference gene is universal, so a systematic characterization of endogenous genes for concrete conditions is fundamental for accuracy. We identified suitable internal control genes to normalize qPCR data obtained at different steps of somatic embryogenesis (embryonal mass proliferation, embryo maturation and germination) in two representative conifer species, Pinus pinaster and Picea abies. Candidate genes included endogenous genes commonly used in conifers, genes previously tested in model plants, and genes with a lower variation of the expression along embryo development according to genome-wide transcript profiling studies. Three different algorithms were used to evaluate expression stability. The geometric average of the expression values of elongation factor-1α, α-tubulin and histone 3 in P. pinaster, and elongation factor-1α, α-tubulin, adenosine kinase and CAC in P. abies were adequate for expression studies throughout somatic embryogenesis. However, improved accuracy was achieved when using other gene combinations in experiments with samples at a single developmental stage. The importance of studies selecting reference genes to use in different tissues or developmental stages within one or close species, and the instability of commonly used reference genes, is highlighted.

Seed plant phylogeny inferred from all three plant genomes: Monophyly of extant gymnosperms and origin of Gnetales from conifers

Science.gov (United States)

Chaw, Shu-Miaw; Parkinson, Christopher L.; Cheng, Yuchang; Vincent, Thomas M.; Palmer, Jeffrey D.

2000-01-01

Phylogenetic relationships among the five groups of extant seed plants are presently quite unclear. For example, morphological studies consistently identify the Gnetales as the extant sister group to angiosperms (the so-called “anthophyte” hypothesis), whereas a number of molecular studies recover gymnosperm monophyly, and few agree with the morphology-based placement of Gnetales. To better resolve these and other unsettled issues, we have generated a new molecular data set of mitochondrial small subunit rRNA sequences, and have analyzed these data together with comparable data sets for the nuclear small subunit rRNA gene and the chloroplast rbcL gene. All nuclear analyses strongly ally Gnetales with a monophyletic conifers, whereas all mitochondrial analyses and those chloroplast analyses that take into account saturation of third-codon position transitions actually place Gnetales within conifers, as the sister group to the Pinaceae. Combined analyses of all three genes strongly support this latter relationship, which to our knowledge has never been suggested before. The combined analyses also strongly support monophyly of extant gymnosperms, with cycads identified as the basal-most group of gymnosperms, Ginkgo as the next basal, and all conifers except for Pinaceae as sister to the Gnetales + Pinaceae clade. According to these findings, the Gnetales may be viewed as extremely divergent conifers, and the many morphological similarities between angiosperms and Gnetales (e.g., double fertilization and flower-like reproductive structures) arose independently. PMID:10760277

Do quantitative vessel and pit characters account for ion-mediated changes in the hydraulic conductance of angiosperm xylem?

NARCIS (Netherlands)

Jansen, S.; Gortan, E.; Lens, F.; Assunta Lo Gullo, M.; Salleo, S.; Scholtz, A.; Stein, A.; Trifilò, P.; Nardini, A.

2011-01-01

• The hydraulic conductance of angiosperm xylem has been suggested to vary with changes in sap solute concentrations because of intervessel pit properties. • The magnitude of the ‘ionic effect’ was linked with vessel and pit dimensions in 20 angiosperm species covering 13 families including six

A remotely sensed pigment index reveals photosynthetic phenology in evergreen conifers

OpenAIRE

Gamon, John A.

2016-01-01

In evergreen conifers, where the foliage amount changes little with season, accurate detection of the underlying “photosynthetic phenology” from satellite remote sensing has been difficult, presenting challenges for global models of ecosystem carbon uptake. Here, we report a close correspondence between seasonally changing foliar pigment levels, expressed as chlorophyll/carotenoid ratios, and evergreen photosynthetic activity, leading to a “chlorophyll/carotenoid index” (CCI) that tracks ever...

Ralstonia solanacearum uses inorganic nitrogen metabolism for virulence, ATP production, and detoxification in the oxygen-limited host xylem environment.

Science.gov (United States)

Dalsing, Beth L; Truchon, Alicia N; Gonzalez-Orta, Enid T; Milling, Annett S; Allen, Caitilyn

2015-03-17

Genomic data predict that, in addition to oxygen, the bacterial plant pathogen Ralstonia solanacearum can use nitrate (NO3(-)), nitrite (NO2(-)), nitric oxide (NO), and nitrous oxide (N2O) as terminal electron acceptors (TEAs). Genes encoding inorganic nitrogen reduction were highly expressed during tomato bacterial wilt disease, when the pathogen grows in xylem vessels. Direct measurements found that tomato xylem fluid was low in oxygen, especially in plants infected by R. solanacearum. Xylem fluid contained ~25 mM NO3(-), corresponding to R. solanacearum's optimal NO3(-) concentration for anaerobic growth in vitro. We tested the hypothesis that R. solanacearum uses inorganic nitrogen species to respire and grow during pathogenesis by making deletion mutants that each lacked a step in nitrate respiration (ΔnarG), denitrification (ΔaniA, ΔnorB, and ΔnosZ), or NO detoxification (ΔhmpX). The ΔnarG, ΔaniA, and ΔnorB mutants grew poorly on NO3(-) compared to the wild type, and they had reduced adenylate energy charge levels under anaerobiosis. While NarG-dependent NO3(-) respiration directly enhanced growth, AniA-dependent NO2(-) reduction did not. NO2(-) and NO inhibited growth in culture, and their removal depended on denitrification and NO detoxification. Thus, NO3(-) acts as a TEA, but the resulting NO2(-) and NO likely do not. None of the mutants grew as well as the wild type in planta, and strains lacking AniA (NO2(-) reductase) or HmpX (NO detoxification) had reduced virulence on tomato. Thus, R. solanacearum exploits host NO3(-) to respire, grow, and cause disease. Degradation of NO2(-) and NO is also important for successful infection and depends on denitrification and NO detoxification systems. The plant-pathogenic bacterium Ralstonia solanacearum causes bacterial wilt, one of the world's most destructive crop diseases. This pathogen's explosive growth in plant vascular xylem is poorly understood. We used biochemical and genetic approaches to show

Influence of light and soil moisture on Sierran mixed-conifer understory communities.

Science.gov (United States)

Malcolm North; Brian Oakley; Rob Fiegener; Andrew Gray; Michael. Barbour

2005-01-01

Sierra Nevada forests have high understory species richness yet we do not know which site factors influence herb and shrub distribution or abundance. We examined the understory of an old-growth mixed-conifer Sierran forest and its distribution in relation to microsite conditions. The forest has high species richness (98 species sampled), most of which are herbs with...

An Ancient Transkingdom Horizontal Transfer of Penelope-Like Retroelements from Arthropods to Conifers.

Science.gov (United States)

Lin, Xuan; Faridi, Nurul; Casola, Claudio

2016-05-02

Comparative genomics analyses empowered by the wealth of sequenced genomes have revealed numerous instances of horizontal DNA transfers between distantly related species. In eukaryotes, repetitive DNA sequences known as transposable elements (TEs) are especially prone to move across species boundaries. Such horizontal transposon transfers, or HTTs, are relatively common within major eukaryotic kingdoms, including animals, plants, and fungi, while rarely occurring across these kingdoms. Here, we describe the first case of HTT from animals to plants, involving TEs known as Penelope-like elements, or PLEs, a group of retrotransposons closely related to eukaryotic telomerases. Using a combination of in situ hybridization on chromosomes, polymerase chain reaction experiments, and computational analyses we show that the predominant PLE lineage, EN(+)PLEs, is highly diversified in loblolly pine and other conifers, but appears to be absent in other gymnosperms. Phylogenetic analyses of both protein and DNA sequences reveal that conifers EN(+)PLEs, or Dryads, form a monophyletic group clustering within a clade of primarily arthropod elements. Additionally, no EN(+)PLEs were detected in 1,928 genome assemblies from 1,029 nonmetazoan and nonconifer genomes from 14 major eukaryotic lineages. These findings indicate that Dryads emerged following an ancient horizontal transfer of EN(+)PLEs from arthropods to a common ancestor of conifers approximately 340 Ma. This represents one of the oldest known interspecific transmissions of TEs, and the most conspicuous case of DNA transfer between animals and plants. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution 2016. This work is written by US Government employees and is in the public domain in the US.

Analysis of spatial and temporal dynamics of xylem refilling in Acer rubrum L. using magnetic resonance imaging.

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Zwieniecki, Maciej A; Melcher, Peter J; Ahrens, Eric T

2013-01-01

We report results of an analysis of embolism formation and subsequent refilling observed in stems of Acer rubrum L. using magnetic resonance imaging (MRI). MRI is one of the very few techniques that can provide direct non-destructive observations of the water content within opaque biological materials at a micrometer resolution. Thus, it has been used to determine temporal dynamics and water distributions within xylem tissue. In this study, we found good agreement between MRI measures of pixel brightness to assess xylem liquid water content and the percent loss in hydraulic conductivity (PLC) in response to water stress (P50 values of 2.51 and 2.70 for MRI and PLC, respectively). These data provide strong support that pixel brightness is well correlated to PLC and can be used as a proxy of PLC even when single vessels cannot be resolved on the image. Pressure induced embolism in moderately stressed plants resulted in initial drop of pixel brightness. This drop was followed by brightness gain over 100 min following pressure application suggesting that plants can restore water content in stem after induced embolism. This recovery was limited only to current-year wood ring; older wood did not show signs of recovery within the length of experiment (16 h). In vivo MRI observations of the xylem of moderately stressed (~-0.5 MPa) A. rubrum stems revealed evidence of a spontaneous embolism formation followed by rapid refilling (~30 min). Spontaneous (not induced) embolism formation was observed only once, despite over 60 h of continuous MRI observations made on several plants. Thus this observation provide evidence for the presence of naturally occurring embolism-refilling cycle in A. rubrum, but it is impossible to infer any conclusions in relation to its frequency in nature.

Lignin depletion enhances the digestibility of cellulose in cultured xylem cells.

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Catherine I Lacayo

Full Text Available Plant lignocellulose constitutes an abundant and sustainable source of polysaccharides that can be converted into biofuels. However, the enzymatic digestion of native plant cell walls is inefficient, presenting a considerable barrier to cost-effective biofuel production. In addition to the insolubility of cellulose and hemicellulose, the tight association of lignin with these polysaccharides intensifies the problem of cell wall recalcitrance. To determine the extent to which lignin influences the enzymatic digestion of cellulose, specifically in secondary walls that contain the majority of cellulose and lignin in plants, we used a model system consisting of cultured xylem cells from Zinniaelegans. Rather than using purified cell wall substrates or plant tissue, we have applied this system to study cell wall degradation because it predominantly consists of homogeneous populations of single cells exhibiting large deposits of lignocellulose. We depleted lignin in these cells by treating with an oxidative chemical or by inhibiting lignin biosynthesis, and then examined the resulting cellulose digestibility and accessibility using a fluorescent cellulose-binding probe. Following cellulase digestion, we measured a significant decrease in relative cellulose content in lignin-depleted cells, whereas cells with intact lignin remained essentially unaltered. We also observed a significant increase in probe binding after lignin depletion, indicating that decreased lignin levels improve cellulose accessibility. These results indicate that lignin depletion considerably enhances the digestibility of cellulose in the cell wall by increasing the susceptibility of cellulose to enzymatic attack. Although other wall components are likely to contribute, our quantitative study exploits cultured Zinnia xylem cells to demonstrate the dominant influence of lignin on the enzymatic digestion of the cell wall. This system is simple enough for quantitative image analysis

Drought-induced xylem cavitation and hydraulic deterioration: risk factors for urban trees under climate change?

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Savi, Tadeja; Bertuzzi, Stefano; Branca, Salvatore; Tretiach, Mauro; Nardini, Andrea

2015-02-01

Urban trees help towns to cope with climate warming by cooling both air and surfaces. The challenges imposed by the urban environment, with special reference to low water availability due to the presence of extensive pavements, result in high rates of mortality of street trees, that can be increased by climatic extremes. We investigated the water relations and xylem hydraulic safety/efficiency of Quercus ilex trees growing at urban sites with different percentages of surrounding impervious pavements. Seasonal changes of plant water potential and gas exchange, vulnerability to cavitation and embolism level, and morpho-anatomical traits were measured. We found patterns of increasing water stress and vulnerability to drought at increasing percentages of impervious pavement cover, with a consequent reduction in gas exchange rates, decreased safety margins toward embolism development, and increased vulnerability to cavitation, suggesting the occurrence of stress-induced hydraulic deterioration. The amount of impermeable surface and chronic exposure to water stress influence the site-specific risk of drought-induced dieback of urban trees under extreme drought. Besides providing directions for management of green spaces in towns, our data suggest that xylem hydraulics is key to a full understanding of the responses of urban trees to global change. © 2014 The Authors. New Phytologist © 2014 New Phytologist Trust.

Potential contribution of exposed resin to ecosystem emissions of monoterpenes

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Eller, Allyson S. D.; Harley, Peter; Monson, Russell K.

2013-10-01

Conifers, especially pines, produce and store under pressure monoterpene-laden resin in canals located throughout the plant. When the plants are damaged and resin canals punctured, the resin is exuded and the monoterpenes are released into the atmosphere, a process that has been shown to influence ecosystem-level monoterpene emissions. Less attention has been paid to the small amounts of resin that are exuded from branches, expanding needles, developing pollen cones, and terminal buds in the absence of any damage. The goal of this study was to provide the first estimate of the potential of this naturally-exposed resin to influence emissions of monoterpenes from ponderosa pine (Pinus ponderosa) ecosystems. When resin is first exuded as small spherical beads from undamaged tissues it emits monoterpenes to the atmosphere at a rate that is four orders of magnitude greater than needle tissue with an equivalent exposed surface area and the emissions from exuded beads decline exponentially as the resin dries. We made measurements of resin beads on the branches of ponderosa pine trees in the middle of the growing season and found, on average, 0.15 cm2 of exposed resin bead surface area and 1250 cm2 of total needle surface area per branch tip. If the resin emerged over the course of 10 days, resin emissions would make up 10% of the ecosystem emissions each day. Since we only accounted for exposed resin at a single point in time, this is probably an underestimate of how much total resin is exuded from undamaged pine tissues over the course of a growing season. Our observations, however, reveal the importance of this previously unrecognized source of monoterpenes emitted from pine forests and its potential to influence regional atmospheric chemistry dynamics.

Measurement of imidacloprid in xylem fluid from eastern hemlock (Tsuga canadensis) by derivitization/GC/MS and ELISA

Science.gov (United States)

Anthony Lagalante; Peter Greenbacker; Jonathan Jones; Richard Turcotte; Bradley Onken

2007-01-01

Imidacloprid is a nonvolatile insecticide and its direct quantification is not possible by gas chromatography. In order to ascertain imidacloprid levels in soil and trunk injection treated trees, a sensitive and selective method has been developed using GC/MS to measure the imidacloprid levels in xylem fluid exudates. In May 2005, a stand of hemlock trees in West...

Conifer reproductive development involves B-type MADS-box genes with distinct and different activities in male organ primordia.

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Sundström, Jens; Engström, Peter

2002-07-01

The Norway spruce MADS-box genes DAL11, DAL12 and DAL13 are phylogenetically related to the angiosperm B-function MADS-box genes: genes that act together with A-function genes in specifying petal identity and with C-function genes in specifying stamen identity to floral organs. In this report we present evidence to suggest that the B-gene function in the specification of identity of the pollen-bearing organs has been conserved between conifers and angiosperms. Expression of DAL11 or DAL12 in transgenic Arabidopsis causes phenotypic changes which partly resemble those caused by ectopic expression of the endogenous B-genes. In similar experiments, flowers of Arabidopsis plants expressing DAL13 showed a different homeotic change in that they formed ectopic anthers in whorls one, two or four. We also demonstrate the capacity of the spruce gene products to form homodimers, and that DAL11 and DAL13 may form heterodimers with each other and with the Arabidopsis B-protein AP3, but not with PI, the second B-gene product in Arabidopsis. In situ hybridization experiments show that the conifer B-like genes are expressed specifically in developing pollen cones, but differ in both temporal and spatial distribution patterns. These results suggest that the B-function in conifers is dual and is separated into a meristem identity and an organ identity function, the latter function possibly being independent of an interaction with the C-function. Thus, even though an ancestral B-function may have acted in combination with C to specify micro- and megasporangia, the B-function has evolved differently in conifers and angiosperms.

Animal damage to conifers on national forests in the Pacific Northwest region.

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Glenn L. Crouch

1969-01-01

Animal damage to conifers is a timely topic in the Pacific Northwest. Foresters in this Region are increasingly concerned and perplexed by damage caused by animals to natural and planted seedlings and larger growing stock. Nearly every animal inhabiting for st land is believed to injure seedlings and small trees to some degree. Mice girdle small trees, and bears girdle...

Leaf water stable isotopes and water transport outside the xylem.

Science.gov (United States)

Barbour, M M; Farquhar, G D; Buckley, T N

2017-06-01

How water moves through leaves, and where the phase change from liquid to vapour occurs within leaves, remain largely mysterious. Some time ago, we suggested that the stable isotope composition of leaf water may contain information on transport pathways beyond the xylem, through differences in the development of gradients in enrichment within the various pathways. Subsequent testing of this suggestion provided ambiguous results and even questioned the existence of gradients in enrichment within the mesophyll. In this review, we bring together recent theoretical developments in understanding leaf water transport pathways and stable isotope theory to map a path for future work into understanding pathways of water transport and leaf water stable isotope composition. We emphasize the need for a spatially, anatomically and isotopically explicit model of leaf water transport. © 2016 John Wiley & Sons Ltd.

Testing the plant pneumatic method to estimate xylem embolism resistance in stems of temperate trees

OpenAIRE

Zhang, Ya; Lamarque, Laurent J.; Torres-Ruiz, José Manuel; Schuldt, Bernhard; Karimi, Zohreh; Li, Shan; Qin, De-Wen; Bittencourt, Paulo; Burlett, Régis; Cao, Kun-Fang; Delzon, Sylvain; Oliveira, Rafael; Pereira, Luciano; Jansen, Steven

2018-01-01

Methods to estimate xylem embolism resistance generally rely on hydraulic measurements, which can be far from straightforward. Recently, a pneumatic method based on air flow measurements of terminal branch ends was proposed to construct vulnerability curves by linking the amount of air extracted from a branch with the degree of embolism. We applied this novel technique for 10 temperate tree species, including six diffuse, two ring-porous and two gymnosperm species, and compared the pneumatic ...

Up-regulation of abscisic acid signaling pathway facilitates aphid xylem absorption and osmoregulation under drought stress.

Science.gov (United States)

Guo, Huijuan; Sun, Yucheng; Peng, Xinhong; Wang, Qinyang; Harris, Marvin; Ge, Feng

2016-02-01

The activation of the abscisic acid (ABA) signaling pathway reduces water loss from plants challenged by drought stress. The effect of drought-induced ABA signaling on the defense and nutrition allocation of plants is largely unknown. We postulated that these changes can affect herbivorous insects. We studied the effects of drought on different feeding stages of pea aphids in the wild-type A17 of Medicago truncatula and ABA signaling pathway mutant sta-1. We examined the impact of drought on plant water status, induced plant defense signaling via the abscisic acid (ABA), jasmonic acid (JA), and salicylic acid (SA) pathways, and on the host nutritional quality in terms of leaf free amino acid content. During the penetration phase of aphid feeding, drought decreased epidermis/mesophyll resistance but increased mesophyll/phloem resistance of A17 but not sta-1 plants. Quantification of transcripts associated with ABA, JA and SA signaling indicated that the drought-induced up-regulation of ABA signaling decreased the SA-dependent defense but increased the JA-dependent defense in A17 plants. During the phloem-feeding phase, drought had little effect on the amino acid concentrations and the associated aphid phloem-feeding parameters in both plant genotypes. In the xylem absorption stage, drought decreased xylem absorption time of aphids in both genotypes because of decreased water potential. Nevertheless, the activation of the ABA signaling pathway increased water-use efficiency of A17 plants by decreasing the stomatal aperture and transpiration rate. In contrast, the water potential of sta-1 plants (unable to close stomata) was too low to support xylem absorption activity of aphids; the aphids on sta-1 plants had the highest hemolymph osmolarity and lowest abundance under drought conditions. Taken together this study illustrates the significance of cross-talk between biotic-abiotic signaling pathways in plant-aphid interaction, and reveals the mechanisms leading to alter

Hydraulic efficiency and safety of vascular and non-vascular components in Pinus pinaster leaves.

Science.gov (United States)

Charra-Vaskou, Katline; Badel, Eric; Burlett, Régis; Cochard, Hervé; Delzon, Sylvain; Mayr, Stefan

2012-09-01

Leaves, the distal section of the soil-plant-atmosphere continuum, exhibit the lowest water potentials in a plant. In contrast to angiosperm leaves, knowledge of the hydraulic architecture of conifer needles is scant. We investigated the hydraulic efficiency and safety of Pinus pinaster needles, comparing different techniques. The xylem hydraulic conductivity (k(s)) and embolism vulnerability (P(50)) of both needle and stem were measured using the cavitron technique. The conductance and vulnerability of whole needles were measured via rehydration kinetics, and Cryo-SEM and 3D X-ray microtomographic observations were used as reference tools to validate physical measurements. The needle xylem of P. pinaster had lower hydraulic efficiency (k(s) = 2.0 × 10(-4) m(2) MPa(-1) s(-1)) and safety (P(50) = - 1.5 MPa) than stem xylem (k(s) = 7.7 × 10(-4) m(2) MPa(-1) s(-1); P(50) = - 3.6 to - 3.2 MPa). P(50) of whole needles (both extra-vascular and vascular pathways) was - 0.5 MPa, suggesting that non-vascular tissues were more vulnerable than the xylem. During dehydration to - 3.5 MPa, collapse and embolism in xylem tracheids, and gap formation in surrounding tissues were observed. However, a discrepancy in hydraulic and acoustic results appeared compared with visualizations, arguing for greater caution with these techniques when applied to needles. Our results indicate that the most distal parts of the water transport pathway are limiting for hydraulics of P. pinaster. Needle tissues exhibit a low hydraulic efficiency and low hydraulic safety, but may also act to buffer short-term water deficits, thus preventing xylem embolism.

Haploids in Conifer Species: Characterization and Chromosomal Integrity of a Maritime Pine Cell Line

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José Antonio Cabezas

2016-11-01

Full Text Available Haploids are a valuable tool for genomic studies in higher plants, especially those with huge genome size and long juvenile periods, such as conifers. In these species, megagametophyte cultures have been widely used to obtain haploid callus and somatic embryogenic lines. One of the main problems associated with tissue culture is the potential genetic instability of the regenerants. Because of this, chromosomal stability of the callus and/or somatic embryos should also be assessed. To this end, chromosome counting, flow cytometry and genotyping using microsatellites have been reported. Here, we present an overview of the work done in conifers, with special emphasis on the production of a haploid cell line in maritime pine (Pinus pinaster L. and the use of a set of molecular markers, which includes Single Nucleotide Polymorphisms (SNPs and microsatellites or Single Sequence Repeats (SSRs, to validate chromosomal integrity confirming the presence of all chromosomic arms.

Epiphytic lichen diversity on dead and dying conifers under different levels of atmospheric pollution

International Nuclear Information System (INIS)

Hauck, Markus

2005-01-01

Based on literature data, epiphytic lichen abundance was comparably studied in montane woodlands on healthy versus dead or dying conifers of Europe and North America in areas with different levels of atmospheric pollution. Study sites comprised Picea abies forests in the Harz Mountains and in the northern Alps, Germany, Picea rubens-Abies balsamea forests on Whiteface Mountain, Adirondacks, New York, U.S.A. and Picea engelmannii-Abies lasiocarpa forests in the Salish Mountains, Montana, U.S.A. Detrended correspondence analysis showed that epiphytic lichen vegetation differed more between healthy and dead or dying trees at high- versus low-polluted sites. This is attributed to greater differences in chemical habitat conditions between trees of different vitality in highly polluted areas. Based on these results, a hypothetical model of relative importance of site factors for small-scale variation of epiphytic lichen abundance versus atmospheric pollutant load is discussed. - Epiphytic lichen diversity differs increasingly between healthy and dead or dying conifers with increasing atmospheric pollutant load

Conifer density within lake catchments predicts fish mercury concentrations in remote subalpine lakes

Science.gov (United States)

Eagles-Smith, Collin A.; Herring, Garth; Johnson, Branden L.; Graw, Rick

2016-01-01

Remote high-elevation lakes represent unique environments for evaluating the bioaccumulation of atmospherically deposited mercury through freshwater food webs, as well as for evaluating the relative importance of mercury loading versus landscape influences on mercury bioaccumulation. The increase in mercury deposition to these systems over the past century, coupled with their limited exposure to direct anthropogenic disturbance make them useful indicators for estimating how changes in mercury emissions may propagate to changes in Hg bioaccumulation and ecological risk. We evaluated mercury concentrations in resident fish from 28 high-elevation, sub-alpine lakes in the Pacific Northwest region of the United States. Fish total mercury (THg) concentrations ranged from 4 to 438 ng/g wet weight, with a geometric mean concentration (±standard error) of 43 ± 2 ng/g ww. Fish THg concentrations were negatively correlated with relative condition factor, indicating that faster growing fish that are in better condition have lower THg concentrations. Across the 28 study lakes, mean THg concentrations of resident salmonid fishes varied as much as 18-fold among lakes. We used a hierarchal statistical approach to evaluate the relative importance of physiological, limnological, and catchment drivers of fish Hg concentrations. Our top statistical model explained 87% of the variability in fish THg concentrations among lakes with four key landscape and limnological variables: catchment conifer density (basal area of conifers within a lake's catchment), lake surface area, aqueous dissolved sulfate, and dissolved organic carbon. Conifer density within a lake's catchment was the most important variable explaining fish THg concentrations across lakes, with THg concentrations differing by more than 400 percent across the forest density spectrum. These results illustrate the importance of landscape characteristics in controlling mercury bioaccumulation in fish.

Shelterwood cutting in a young-growth, mixed-conifer stand in north central California

Science.gov (United States)

Philip M. McDonald

1976-01-01

A two-stage shelterwood cutting, at 12 trees per acre, with site preparation, enhanced seedfall, regeneration, and residual growth at the Challenge Experimental Forest, north central California. Shelterwood trees produced 9.2 times more seed than trees in the control. Ponderosa pine regeneration numbered about 3700 seedlings per acre (9139 per ha) and tolerant conifers...

Coarse woody debris assay in northern Arizona mixed-conifer and ponderosa pine forests

Science.gov (United States)

Joseph L. Ganey; Scott C. Vojta

2010-01-01

Coarse woody debris (CWD) provides important ecosystem services in forests and affects fire behavior, yet information on amounts and types of CWD typically is limited. To provide such information, we sampled logs and stumps in mixed-conifer and ponderosa pine (Pinus ponderosa) forests in north-central Arizona. Spatial variability was prominent for all CWD parameters....

Dendrochronology and radiocarbon dating of conifer trees and buried logs from the Stanley River, Tasmania

Energy Technology Data Exchange (ETDEWEB)

Cook, E. [Columbia Univ., Palisades, NY (United States). Tree-Ring Lab; Barbetti, M.; Taylor, G.; Yu, Z.; Thompson, B.; Weeks, L. [Sydney Univ., Sydney, NSW (Australia). The NWG Macintosh Centre for Quaternary Dating; Buckley, B. [Tasmania Univ., Sandy Bay, TAS (Australia). Inst of Antarctic and Southern Ocean Studies

1997-12-31

Full text: Dendrochronological studies are being carried out on two endemic conifer species in the Stanley River area of western Tasmania. Living trees are growing along the river banks, adjacent floodplain areas, and occasionally on the lower hill-slopes. Many ancient logs are exposed in the bed and banks of the river, and several major excavations have been carried out in floodplain sediments up to a hundred metres distant from the present river channel. A tree-ring chronology for Huon pine (Lagarostrobos franklinii) now extends from the present back to 571 BC. This chronology has been constructed using cores from living trees (up to 1400 years old), sections from trees felled during logging operations in the early 1980s, and sections from subfossil logs in the river banks and floodplain sediments. Living celery-top pine (Phyllocladus aspleniifolius) trees are up to 500 years old, and a short chronology is being developed for this species as well. Large excavations have been carried out over several years in floodplain sediments, and sections have now been taken from a total of 350 subfossil logs. Both Huon and celery-top pine are represented in the collection. They range in age from >38 ka to modern, with good coverage for the periods 9-3.5 ka and from 2.5 ka to the present. A floating tree-ring chronology for Huon pine has been established for the period ca. 7200-3500 cal BP, and is gradually being augmented. In the collection of about 350 ancient conifer logs from the Stanley River, about 150 currently have known ages while the remaining 200 have yet to be studied. Most of them have ages less than 9000 cal BP, but about 10% of them are older. Four of them are more than 30,000 years old, and may be Last Interglacial in age. Nine of them are known to be between 18,000 and 10,000 years old, and six are between 10,000 and 9,000 years old. Our augmented collection has become an increasingly important archive for further tree-ring and carbon isotope studies. Paper

Dendrochronology and radiocarbon dating of conifer trees and buried logs from the Stanley River, Tasmania

International Nuclear Information System (INIS)

Cook, E.; Barbetti, M.; Taylor, G.; Yu, Z.; Thompson, B.; Weeks, L.; Buckley, B.

1997-01-01

Full text: Dendrochronological studies are being carried out on two endemic conifer species in the Stanley River area of western Tasmania. Living trees are growing along the river banks, adjacent floodplain areas, and occasionally on the lower hill-slopes. Many ancient logs are exposed in the bed and banks of the river, and several major excavations have been carried out in floodplain sediments up to a hundred metres distant from the present river channel. A tree-ring chronology for Huon pine (Lagarostrobos franklinii) now extends from the present back to 571 BC. This chronology has been constructed using cores from living trees (up to 1400 years old), sections from trees felled during logging operations in the early 1980s, and sections from subfossil logs in the river banks and floodplain sediments. Living celery-top pine (Phyllocladus aspleniifolius) trees are up to 500 years old, and a short chronology is being developed for this species as well. Large excavations have been carried out over several years in floodplain sediments, and sections have now been taken from a total of 350 subfossil logs. Both Huon and celery-top pine are represented in the collection. They range in age from >38 ka to modern, with good coverage for the periods 9-3.5 ka and from 2.5 ka to the present. A floating tree-ring chronology for Huon pine has been established for the period ca. 7200-3500 cal BP, and is gradually being augmented. In the collection of about 350 ancient conifer logs from the Stanley River, about 150 currently have known ages while the remaining 200 have yet to be studied. Most of them have ages less than 9000 cal BP, but about 10% of them are older. Four of them are more than 30,000 years old, and may be Last Interglacial in age. Nine of them are known to be between 18,000 and 10,000 years old, and six are between 10,000 and 9,000 years old. Our augmented collection has become an increasingly important archive for further tree-ring and carbon isotope studies

Leaf hydraulic capacity in ferns, conifers and angiosperms: impacts on photosynthetic maxima.

Science.gov (United States)

Brodribb, Tim J; Holbrook, N Michele; Zwieniecki, Maciej A; Palma, Beatriz

2005-03-01

* The hydraulic plumbing of vascular plant leaves varies considerably between major plant groups both in the spatial organization of veins, as well as their anatomical structure. * Five conifers, three ferns and 12 angiosperm trees were selected from tropical and temperate forests to investigate whether the profound differences in foliar morphology of these groups lead to correspondingly profound differences in leaf hydraulic efficiency. * We found that angiosperm leaves spanned a range of leaf hydraulic conductance from 3.9 to 36 mmol m2 s-1 MPa-1, whereas ferns (5.9-11.4 mmol m-2 s-1 MPa-1) and conifers (1.6-9.0 mmol m-2 s-1 MPa-1) were uniformly less conductive to liquid water. Leaf hydraulic conductance (Kleaf) correlated strongly with stomatal conductance indicating an internal leaf-level regulation of liquid and vapour conductances. Photosynthetic capacity also increased with Kleaf, however, it became saturated at values of Kleaf over 20 mmol m-2 s-1 MPa-1. * The data suggest that vessels in the leaves of the angiosperms studied provide them with the flexibility to produce highly conductive leaves with correspondingly high photosynthetic capacities relative to tracheid-bearing species.

Cenozoic climate change shaped the evolutionary ecophysiology of the Cupressaceae conifers

OpenAIRE

Pittermann, Jarmila; Stuart, Stephanie A.; Dawson, Todd E.; Moreau, Astrid

2012-01-01

The Cupressaceae clade has the broadest diversity in habitat and morphology of any conifer family. This clade is characterized by highly divergent physiological strategies, with deciduous swamp-adapted genera-like Taxodium at one extreme, and evergreen desert genera-like Cupressus at the other. The size disparity within the Cupressaceae is equally impressive, with members ranging from 5-m-tall juniper shrubs to 100-m-tall redwood trees. Phylogenetic studies demonstrate that despite this varia...

Phenology and abundance of Enoicyla pusilla in conifer stands

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M. J. Lombardero

2013-07-01

Full Text Available Aim of Study. We study the abundance of Enoicyla pusilla (Burmeister in pine plantations and the effects of silvicultural thinning on insect population. This species is considered a rare member of the order Trichoptera, reported as absent or occasional in conifer forests. It has been suggested that the proliferation of conifer plantations may be a threat for this species by favoring population isolation. Area of study. Plantations of native and non-native pines in Galicia (NW of Spain.Material and Methods. We used different traps systems, including 28 pitfall traps, to compared populations of insects in 14 thinned and unthinned plots of Pinus pinaster and P. radiata distributed across 3 forest stands. Traps were checked every 15 days during one year.Main results.  We caught 1.219 larvae of E. pusilla. It was the third most abundant species captured in pitfall traps. Larval activity extended from January to late July. They were more abundant in the stands of P. radiata, probably because the denser foliage produced limits sunlight and helped to maintain litter moisture. Additionally needles of P. radiata had lower toughness and higher nitrogen content, which probably makes it a higher quality resource for the detritivorous larvae. Thinning did not affect larvae population.Research highlights: Although managed forests cannot match the biodiversity value of native mixed species stands, if managed appropriately, they may provide habitat for native fauna while also allowing for forest productionKey words: caddisfly; Pinus pinaster; Pinus radiate; plantations; thinning.

Effect of root pruning and irrigation regimes on leaf water relations and xylem ABA and ionic concentrations in pear trees

DEFF Research Database (Denmark)

Wang, Yufei; Bertelsen, Marianne G.; Petersen, Karen Koefoed

2014-01-01

relation characteristics, stomatal conductance and xylem sap abscisic acid (ABA) and ionic concentrations. Results showed that leaf water potential, leaf turgor and stomatal conductance of root pruning (RP) treatment was significantly lower than those of non-root pruning (NP) treatment indicating that root...

Microtubule-dependent targeting of the exocyst complex is necessary for xylem development in Arabidopsis

Czech Academy of Sciences Publication Activity Database

Vukašinović, Nemanja; Oda, Y.; Pejchar, Přemysl; Synek, Lukáš; Pečenková, Tamara; Rawat, Anamika; Sekereš, Juraj; Potocký, Martin; Žárský, Viktor

2017-01-01

Roč. 213, č. 3 (2017), s. 1052-1067 ISSN 0028-646X R&D Projects: GA ČR(CZ) GA15-14886S Grant - others:GA MŠk(CZ) LO1417 Institutional support: RVO:61389030 Keywords : secondary cell-wall * tracheary element differentiation * cortical microtubules * plasma-membrane * vesicle trafficking * secretory pathways * auxin transport * exocytosis * deposition * thaliana * conserved oligomeric Golgi (COG) complex * exocyst * microtubules * secondary cell wall * tracheary elements * xylem Subject RIV: EB - Genetics ; Molecular Biology OBOR OECD: Cell biology Impact factor: 7.330, year: 2016

Introducing wood anatomical and dendrochronological aspects of herbaceous plants: applications of the Xylem Database to vegetation science

Czech Academy of Sciences Publication Activity Database

Büntgen, Ulf; Psomas, A.; Schweingruber, F. H.

2014-01-01

Roč. 25, č. 4 (2014), s. 967-977 ISSN 1100-9233 R&D Projects: GA MŠk(CZ) EE2.3.20.0248 Institutional support: RVO:67179843 Keywords : dendrochronology * dicotyledon * environmental change * functional traits * herbs * life form * non-forest vegetation * secondary growth * shrub * vegetation cover * wood anatomy * Xylem formation Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 3.709, year: 2014

Analysis of spatial and temporal dynamics of xylem refilling in Acer rubrum L. using magnetic resonance imaging (MRI.

Directory of Open Access Journals (Sweden)

Maciej Andrzej Zwieniecki

2013-07-01

Full Text Available We report results of an analysis of embolism formation and subsequent refilling observed in stems of Acer rubrum L. using magnetic resonance imaging (MRI. MRI is one of the very few techniques that can provide direct non-destructive observations of the water content within opaque biological materials at a micrometer resolution. Thus, it has been used to determine temporal dynamics and water distributions within xylem tissue. In this study, we found good agreement between MRI measures of pixel brightness to assess xylem liquid water content and the percent loss in hydraulic conductivity (PLC in response to water stress (P50 values of 2.51 and 2.70 for MRI and PLC, respectively. These data provide strong support that pixel brightness is well correlated to PLC and can be used as a proxy of PLC even when single vessels cannot be resolved on the image. Pressure induced embolism in moderately stressed plants resulted in initial drop of pixel brightness. This drop was followed by brightness gain over 100 minutes following pressure application suggesting that plants can restore water content in stem after induced embolism. This recovery was limited only to current year wood ring; older wood did not show signs of recovery within the length of experiment (16 hours. In vivo MRI observations of the xylem of moderately stressed (~-0.5 MPa A. rubrum stems revealed evidence of a spontaneous embolism formation followed by rapid refilling (~30 minutes. Spontaneous (not induced embolism formation was observed only once, despite over 60 hours of continuous MRI observations made on several plants. Thus this observation provide evidence for presence of naturally occurring embolism-refilling cycle in A. rubrum, but it is impossible to infer any conclusions in relation to its frequency in nature.

A rhamnose-rich O-antigen mediates adhesion, virulence, and host colonization for the xylem-limited phytopathogen Xylella fastidiosa.

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Clifford, Jennifer C; Rapicavoli, Jeannette N; Roper, M Caroline

2013-06-01

Xylella fastidiosa is a gram-negative, xylem-limited bacterium that causes a lethal disease of grapevine called Pierce's disease. Lipopolysaccharide (LPS) composes approximately 75% of the outer membrane of gram-negative bacteria and, because it is largely displayed on the cell surface, it mediates interactions between the bacterial cell and its surrounding environment. LPS is composed of a conserved lipid A-core oligosaccharide component and a variable O-antigen portion. By targeting a key O-antigen biosynthetic gene, we demonstrate the contribution of the rhamnose-rich O-antigen to surface attachment, cell-cell aggregation, and biofilm maturation: critical steps for successful infection of the host xylem tissue. Moreover, we have demonstrated that a fully formed O-antigen moiety is an important virulence factor for Pierce's disease development in grape and that depletion of the O-antigen compromises its ability to colonize the host. It has long been speculated that cell-surface polysaccharides play a role in X. fastidiosa virulence and this study confirms that LPS is a major virulence factor for this important agricultural pathogen.

Regeneration in mixed conifer shelterwood cuttings in the Cascade Range of eastern Oregon.

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K.W. Seidel

1979-01-01

A survey of shelterwood cuttings in mixed conifer forests in the eastern Oregon Cascade Range showed that, on the average, shelterwood units were well stocked with a mixture of advance, natural subsequent, and planted reproduction of a number of species. Because of slow invasion by understory vegetation, frequent heavy seed crops, and adequate density of the overstory...

Influence of elevation and site productivity on conifer distributions across Alaskan temperate rainforests

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John P. Caouette; Ashley E. Steel; Paul E. Hennon; Pat G. Cunningham; Cathy A. Pohl; Barbara A. Schrader

2016-01-01

We investigated the influence of landscape factors on the distribution and life stage stability of coastal tree species near the northern limit of their ranges. Using data from 1465 forest inventory plots, we estimated probability of occurrence and basal area of six common conifer species across three broad latitudinal regions of coastal Alaska. By also comparing...

Fast-growing Acer rubrum differs from slow-growing Quercus alba in leaf, xylem and hydraulic trait coordination responses to simulated acid rain.

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Medeiros, Juliana S; Tomeo, Nicholas J; Hewins, Charlotte R; Rosenthal, David M

2016-08-01

We investigated the effects of historic soil chemistry changes associated with acid rain, i.e., reduced soil pH and a shift from nitrogen (N)- to phosphorus (P)-limitation, on the coordination of leaf water demand and xylem hydraulic supply traits in two co-occurring temperate tree species differing in growth rate. Using a full-factorial design (N × P × pH), we measured leaf nutrient content, water relations, leaf-level and canopy-level gas exchange, total biomass and allocation, as well as stem xylem anatomy and hydraulic function for greenhouse-grown saplings of fast-growing Acer rubrum (L.) and slow-growing Quercus alba (L.). We used principle component analysis to characterize trait coordination. We found that N-limitation, but not P-limitation, had a significant impact on plant water relations and hydraulic coordination of both species. Fast-growing A. rubrum made hydraulic adjustments in response to N-limitation, but trait coordination was variable within treatments and did not fully compensate for changing allocation across N-availability. For slow-growing Q. alba, N-limitation engendered more strict coordination of leaf and xylem traits, resulting in similar leaf water content and hydraulic function across all treatments. Finally, low pH reduced the propensity of both species to adjust leaf water relations and xylem anatomical traits in response to nutrient manipulations. Our data suggest that a shift from N- to P-limitation has had a negative impact on the water relations and hydraulic function of A. rubrum to a greater extent than for Q. alba We suggest that current expansion of A. rubrum populations could be tempered by acidic N-deposition, which may restrict it to more mesic microsites. The disruption of hydraulic acclimation and coordination at low pH is emphasized as an interesting area of future study. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

The application of carbon-isotope measurements to dendro- and xylem-chronology

International Nuclear Information System (INIS)

Yonenobu, Hitoshi; Hattori, Yoshiaki; Kikata, Yoji; Mitsutani, Takumi; Nakamura, Toshio.

1990-01-01

We measured 14 C/ 13 C Ratio of the Teak. The 14 C excess, which reflects the execution of the tropospheric nuclear tests, is stamped in the Teak trunk. In place of the annual rings this stamp can estimate the xylem-chronologies and more accurate growth rates of tropical trees which have no annual rings. And replacing the shot-pinning method we can estimate the growing period in an annual ring formed especially in 1963-1966, when the 14 C concentration in the tropospheric air changes dramatically. And we measured 14 C-chronologies of the annual rings of O-Hinoki, 14 C-chronologies agree well with dendrochronologies for the past 600 years. And the 14 C chronologies support more determinative cross-dating of the archaeological samples. (author)

Hydraulic Limits on Maximum Plant Transpiration

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Manzoni, S.; Vico, G.; Katul, G. G.; Palmroth, S.; Jackson, R. B.; Porporato, A. M.

2011-12-01

Photosynthesis occurs at the expense of water losses through transpiration. As a consequence of this basic carbon-water interaction at the leaf level, plant growth and ecosystem carbon exchanges are tightly coupled to transpiration. In this contribution, the hydraulic constraints that limit transpiration rates under well-watered conditions are examined across plant functional types and climates. The potential water flow through plants is proportional to both xylem hydraulic conductivity (which depends on plant carbon economy) and the difference in water potential between the soil and the atmosphere (the driving force that pulls water from the soil). Differently from previous works, we study how this potential flux changes with the amplitude of the driving force (i.e., we focus on xylem properties and not on stomatal regulation). Xylem hydraulic conductivity decreases as the driving force increases due to cavitation of the tissues. As a result of this negative feedback, more negative leaf (and xylem) water potentials would provide a stronger driving force for water transport, while at the same time limiting xylem hydraulic conductivity due to cavitation. Here, the leaf water potential value that allows an optimum balance between driving force and xylem conductivity is quantified, thus defining the maximum transpiration rate that can be sustained by the soil-to-leaf hydraulic system. To apply the proposed framework at the global scale, a novel database of xylem conductivity and cavitation vulnerability across plant types and biomes is developed. Conductivity and water potential at 50% cavitation are shown to be complementary (in particular between angiosperms and conifers), suggesting a tradeoff between transport efficiency and hydraulic safety. Plants from warmer and drier biomes tend to achieve larger maximum transpiration than plants growing in environments with lower atmospheric water demand. The predicted maximum transpiration and the corresponding leaf water

Xylem anatomy of the Caesalpiniaceae registered in wood collection of the Universidad Distrital Francisco Jose de Caldas

International Nuclear Information System (INIS)

Pulido Rodriguez, Esperanza N; Mateus, Durley; Lozano D, Ivan

2011-01-01

The anatomical study of the xylem of 21 species of Caesalpiniaceae registered in the wood collection Jos Anatolio Lastra Rivera (JALR), of the Universidad Distrital Francisco Jose de Caldas, included the macroscopic, microscopic and biometric characterization of the cellular elements that constitute the xylematic tissue. These analyses were developed following parameters defined by the International Association Wood Anatomist Committee (IAWA Committee 1989) and methods established by the Wood Technology Laboratory of Universidad Distrital. Measurements and descriptions were used to prepare identification keys and similarity analysis. The wood of Caesalpiniaceae family illustrated common characteristics in growth rings differentiation, porosity, vessel arrangement, deposits, diameter and length, plates perforation type, alternate and vestured intervessel pits; fibers wall thickness and length; paratracheal axial vasicentric parenchyma, aliform and banded parenchyma and presence of prismatic crystals. Also, variations in anatomical features such us longitudinal channels were found as diagnostic for some genera like Copaifera. The variation and analysis of anatomical characteristics of the xylem tissue allowed to verify some taxonomic relations of the family Caesalpiniaceae, like the observed with the species Mora megistosperma, Mora oleofera, Peltogyne pubescens, Peltogyne paniculata, Sclerolobium odoratissimum and Tachigali polyphylla .

Diagnosis of Annosus Root Disease in Mixed Conifer Forests in the Northwestern United States

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Craig L. Schmitt

1989-01-01

Recognizing annosus root disease affecting conifers in northwestern United States forests is discussed. Field diagnosis can bemade by observing characteristic stand patterns, wood stain and decay, ectotrophic mycelium, and sporophores. Most seriously affected trees include hemlocks, grand fir, white fir and Pacific silver fir. Ponderosa pine and other true firs may...

Water transport through tall trees: A vertically-explicit, analytical model of xylem hydraulic conductance in stems.

Science.gov (United States)

Couvreur, Valentin; Ledder, Glenn; Manzoni, Stefano; Way, Danielle A; Muller, Erik B; Russo, Sabrina E

2018-05-08

Trees grow by vertically extending their stems, so accurate stem hydraulic models are fundamental to understanding the hydraulic challenges faced by tall trees. Using a literature survey, we showed that many tree species exhibit continuous vertical variation in hydraulic traits. To examine the effects of this variation on hydraulic function, we developed a spatially-explicit, analytical water transport model for stems. Our model allows Huber ratio, stem-saturated conductivity, pressure at 50% loss of conductivity, leaf area, and transpiration rate to vary continuously along the hydraulic path. Predictions from our model differ from a matric flux potential model parameterized with uniform traits. Analyses show that cavitation is a whole-stem emergent property resulting from nonlinear pressure-conductivity feedbacks that, with gravity, cause impaired water transport to accumulate along the path. Because of the compounding effects of vertical trait variation on hydraulic function, growing proportionally more sapwood and building tapered xylem with height, as well as reducing xylem vulnerability only at branch tips while maintaining transport capacity at the stem base, can compensate for these effects. We therefore conclude that the adaptive significance of vertical variation in stem hydraulic traits is to allow trees to grow tall and tolerate operating near their hydraulic limits. This article is protected by copyright. All rights reserved.

Soil fertility affects elemental distribution in needles of the conifer Araucaria angustifolia: A microanalytical study

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Araucaria angustifolia is a conifer species found in South American subtropical forests that comprises less than 3% of the native vegetation. Thus, little is known concerning the accumulation of nutritional elements in its needles. In this study, scanning electron microscopy (SEM) coupled with energ...

A comparative study of modern and fossil cone scales and seeds of conifers: A geochemical approach

Science.gov (United States)

Artur, Stankiewicz B.; Mastalerz, Maria; Kruge, M.A.; Van Bergen, P. F.; Sadowska, A.

1997-01-01

Modern cone scales and seeds of Pinus strobus and Sequoia sempervirens, and their fossil (Upper Miocene, c. 6 Mar) counterparts Pinus leitzii and Sequoia langsdorfi have been studied using pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), electron-microprobe and scanning electron microscopy. Microscopic observations revealed only minor microbial activity and high-quality structural preservation of the fossil material. The pyrolysates of both modern genera showed the presence of ligno-cellulose characteristic of conifers. However, the abundance of (alkylated)phenols and 1,2-benzenediols in modern S. sempervirens suggests the presence of non-hydrolysable tannins or abundant polyphenolic moieties not previously reported in modern conifers. The marked differences between the pyrolysis products of both modern genera are suggested to be of chemosystematic significance. The fossil samples also contained ligno-cellulose which exhibited only partial degradation, primarily of the carbohydrate constituents. Comparison between the fossil cone scale and seed pyrolysates indicated that the ligno-cellulose complex present in the seeds is chemically more resistant than that in the cone scales. Principal component analysis (PCA) of the pyrolysis data allowed for the determination of the discriminant functions used to assess the extent of degradation and the chemosystematic differences between both genera and between cone scales and seeds. Elemental composition (C, O, S), obtained using electron-microprobe, corroborated the pyrolysis results. Overall, the combination of chemical, microscopic and statistical methods allowed for a detailed characterization and chemosystematic interpretations of modern and fossil conifer cone scales and seeds.

Linking xylem water storage with anatomical parameters in five temperate tree species.

Science.gov (United States)

Jupa, Radek; Plavcová, Lenka; Gloser, Vít; Jansen, Steven

2016-06-01

The release of water from storage compartments to the transpiration stream is an important functional mechanism that provides the buffering of sudden fluctuations in water potential. The ability of tissues to release water per change in water potential, referred to as hydraulic capacitance, is assumed to be associated with the anatomy of storage tissues. However, information about how specific anatomical parameters determine capacitance is limited. In this study, we measured sapwood capacitance (C) in terminal branches and roots of five temperate tree species (Fagus sylvatica L., Picea abies L., Quercus robur L., Robinia pseudoacacia L., Tilia cordata Mill.). Capacitance was calculated separately for water released mainly from capillary (CI; open vessels, tracheids, fibres, intercellular spaces and cracks) and elastic storage compartments (CII; living parenchyma cells), corresponding to two distinct phases of the moisture release curve. We found that C was generally higher in roots than branches, with CI being 3-11 times higher than CII Sapwood density and the ratio of dead to living xylem cells were most closely correlated with C In addition, the magnitude of CI was strongly correlated with fibre/tracheid lumen area, whereas CII was highly dependent on the thickness of axial parenchyma cell walls. Our results indicate that water released from capillary compartments predominates over water released from elastic storage in both branches and roots, suggesting the limited importance of parenchyma cells for water storage in juvenile xylem of temperate tree species. Contrary to intact organs, water released from open conduits in our small wood samples significantly increased CI at relatively high water potentials. Linking anatomical parameters with the hydraulic capacitance of a tissue contributes to a better understanding of water release mechanisms and their implications for plant hydraulics. © The Author 2016. Published by Oxford University Press. All rights

Xylem and Leaf Functional Adjustments to Drought in Pinus sylvestris and Quercus pyrenaica at Their Elevational Boundary.

Science.gov (United States)

Fernández-de-Uña, Laura; Rossi, Sergio; Aranda, Ismael; Fonti, Patrick; González-González, Borja D; Cañellas, Isabel; Gea-Izquierdo, Guillermo

2017-01-01

Climatic scenarios for the Mediterranean region forecast increasing frequency and intensity of drought events. Consequently, a reduction in Pinus sylvestris L. distribution range is projected within the region, with this species being outcompeted at lower elevations by more drought-tolerant taxa such as Quercus pyrenaica Willd. The functional response of these species to the projected shifts in water availability will partially determine their performance and, thus, their competitive success under these changing climatic conditions. We studied how the cambial and leaf phenology and xylem anatomy of these two species responded to a 3-year rainfall exclusion experiment set at their elevational boundary in Central Spain. Additionally, P. sylvestris leaf gas exchange, water potential and carbon isotope content response to the treatment were measured. Likewise, we assessed inter-annual variability in the studied functional traits under control and rainfall exclusion conditions. Prolonged exposure to drier conditions did not affect the onset of xylogenesis in either of the studied species, whereas xylem formation ceased 1-3 weeks earlier in P. sylvestris . The rainfall exclusion had, however, no effect on leaf phenology on either species, which suggests that cambial phenology is more sensitive to drought than leaf phenology. P. sylvestris formed fewer, but larger tracheids under dry conditions and reduced the proportion of latewood in the tree ring. On the other hand, Q. pyrenaica did not suffer earlywood hydraulic diameter changes under rainfall exclusion, but experienced a cumulative reduction in latewood width, which could ultimately challenge its hydraulic performance. The phenological and anatomical response of the studied species to drought is consistent with a shift in resource allocation under drought stress from xylem to other sinks. Additionally, the tighter stomatal control and higher intrinsic water use efficiency observed in drought-stressed P. sylvestris

Xylem and Leaf Functional Adjustments to Drought in Pinus sylvestris and Quercus pyrenaica at Their Elevational Boundary

Directory of Open Access Journals (Sweden)

Laura Fernández-de-Uña

2017-07-01

Full Text Available Climatic scenarios for the Mediterranean region forecast increasing frequency and intensity of drought events. Consequently, a reduction in Pinus sylvestris L. distribution range is projected within the region, with this species being outcompeted at lower elevations by more drought-tolerant taxa such as Quercus pyrenaica Willd. The functional response of these species to the projected shifts in water availability will partially determine their performance and, thus, their competitive success under these changing climatic conditions. We studied how the cambial and leaf phenology and xylem anatomy of these two species responded to a 3-year rainfall exclusion experiment set at their elevational boundary in Central Spain. Additionally, P. sylvestris leaf gas exchange, water potential and carbon isotope content response to the treatment were measured. Likewise, we assessed inter-annual variability in the studied functional traits under control and rainfall exclusion conditions. Prolonged exposure to drier conditions did not affect the onset of xylogenesis in either of the studied species, whereas xylem formation ceased 1–3 weeks earlier in P. sylvestris. The rainfall exclusion had, however, no effect on leaf phenology on either species, which suggests that cambial phenology is more sensitive to drought than leaf phenology. P. sylvestris formed fewer, but larger tracheids under dry conditions and reduced the proportion of latewood in the tree ring. On the other hand, Q. pyrenaica did not suffer earlywood hydraulic diameter changes under rainfall exclusion, but experienced a cumulative reduction in latewood width, which could ultimately challenge its hydraulic performance. The phenological and anatomical response of the studied species to drought is consistent with a shift in resource allocation under drought stress from xylem to other sinks. Additionally, the tighter stomatal control and higher intrinsic water use efficiency observed in drought

Vegetation recovery in slash-pile scars following conifer removal in a grassland-restoration experiment

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Charles B. Halpern; Joseph A. Antos; Liam M. Beckman

2014-01-01

A principal challenge to restoring tree-invaded grasslands is the removal of woody biomass. Burning of slash piles to reduce woody residues from forest restoration practices generates intense, prolonged heating, with adverse effects on soils and vegetation. In this study, we examined vegetation responses to pile burning following tree removal from conifer-invaded...

Historical dominance of low-severity fire in dry and wet mixed-conifer forest habitats of the endangered terrestrial Jemez Mountains salamander (Plethodon neomexicanus)

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Margolis, Ellis; Malevich, Steven B.

2016-01-01

Anthropogenic alteration of ecosystem processes confounds forest management and conservation of rare, declining species. Restoration of forest structure and fire hazard reduction are central goals of forest management policy in the western United States, but restoration priorities and treatments have become increasingly contentious. Numerous studies have documented changes in fire regimes, forest stand structure and species composition following a century of fire exclusion in dry, frequent-fire forests of the western U.S. (e.g., ponderosa pine and dry mixed-conifer). In contrast, wet mixed-conifer forests are thought to have historically burned infrequently with mixed- or high-severity fire—resulting in reduced impacts from fire exclusion and low restoration need—but data are limited. In this study we quantified the current forest habitat of the federally endangered, terrestrial Jemez Mountains salamander (Plethodon neomexicanus) and compared it to dendroecological reconstructions of historical habitat (e.g., stand structure and composition), and fire regime parameters along a gradient from upper ponderosa pine to wet mixed-conifer forests. We found that current fire-free intervals in Jemez Mountains salamander habitat (116–165 years) are significantly longer than historical intervals, even in wet mixed-conifer forests. Historical mean fire intervals ranged from 10 to 42 years along the forest gradient. Low-severity fires were historically dominant across all forest types (92 of 102 fires). Although some mixed- or highseverity fire historically occurred at 67% of the plots over the last four centuries, complete mortality within 1.0 ha plots was rare, and asynchronous within and among sites. Climate was an important driver of temporal variability in fire severity, such that mixed- and high-severity fires were associated with more extreme drought than low-severity fires. Tree density in dry conifer forests historically ranged from open (90 trees/ha) to

The timing of bud break in warming conditions: variation among seven sympatric conifer species from Eastern Canada

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Rossi, Sergio; Isabel, Nathalie

2017-11-01

Phenological changes are expected with the ongoing global warming, which could create mismatches in the growth patterns among sympatric species or create synchrony with insect herbivores. In this study, we performed a comparative assessment of the timings of bud break among seven conifer species of Eastern Canada by evaluating seedling development in growth chambers under different temperatures (16, 20 and 24 °C). Bud break occurred earliest in Larix laricina, while Pinus strobus and Pinus resinosa had the latest. Warmer conditions advanced bud break, with the greatest effects being observed at the lower temperatures. Mixed models estimated that one additional degree of temperature produced advancements of 5.3 and 2.1 days at 16 and 20 °C, respectively. The hypothesis of an asynchronous change between species under warming was demonstrated only for the last phenological phases (split buds and exposed shoots), and principally in pines. Abies balsamea showed changes in bud break comparable with the other species analysed, rejecting the hypothesis of mismatches under warmer conditions. The observed non-linear responses of the timings of bud break to warming suggest that the major changes in bud phenology should be expected at the lowest temperatures.

Effects of sulfur dioxide on conifers

Energy Technology Data Exchange (ETDEWEB)

Govi, G.; Tagliani, F.; Cimino, A.

1974-01-01

Trials on the resistance of several conifer and oak species to the effects of sulfur dioxide at different concentrations and moisture levels were conducted. 72 combinations were experimented. The damages began to appear under the following conditions: Abies alba: 0.3 ppm, 25/sup 0/C, 70% ur after 24 hours; Picea excelsa: 0.3 ppm, 15/sup 0/C, 70-95% ur after 24 hours; Cedrus deodara: 0.3 ppm, 15/sup 0/C, 95% ur after 48 hours; Pinus pinea: 0.3 ppm, 15/sup 0/C, 70-95% after 72 hours; Pinus strobus 0.3 ppm, 25/sup 0/C, 70-95%, after 48 hours; Pinus pinaster: similar to the former; Pinus nigra: 2 ppm, 25/sup 0/C, 70-95%, ur after 5 days; Cupressus arizonica and C. semperivirens: 2 ppm, 25%/sup 0/C, 90% ur after 72 hours; Quercus robur: 5 ppm, 25/sup 0/C, 90% ur, after 10 days. 6 references, 3 figures, 1 table.

Acid mist and ozone effects on the leaf chemistry of two western conifer species

Science.gov (United States)

Westman, Walter E.; Temple, Patrick J.

1989-01-01

The effects of ozone and acid-mist exposures on the leaf chemistry of Jeffrey pine and giant sequoia seedlings grown in filtered-air greenhouses were investigated. Acid-mist treatments (pH 4.1, 3.4, 2.7, or 2.0) were administered for 3 h, and ozone exposures (0, 0.10, and 0.20 microliter/liter), which followed acid-mist treatments, for 4 h, each for three days a week for six to nine weeks. It was found that seedlings were more susceptible to acid-mist and acid mist/ozone combinations, than to ozone alone. Acid mist treatment resulted in higher levels of nitrogen and sulfur (both present in acid mist) as well as Na. Leaves of giant sequoia exhibited increased K and decreased Mn, while Jeffrey pine showed increases in Fe and Mn. In sequoia leaves, concentrations of Ca, Mg, and Ba decreased. Acid treatment also reduced chlorophyll b concentrations in both conifer species. Extensive changes induced by acid mist are consistent with earlier observations of changes in spectral reflectance of conifer seedlings observed after three weeks of fumigation.

Examining historical and current mixed-severity fire regimes in ponderosa pine and mixed-conifer forests of western North America.

Directory of Open Access Journals (Sweden)

Dennis C Odion

Full Text Available There is widespread concern that fire exclusion has led to an unprecedented threat of uncharacteristically severe fires in ponderosa pine (Pinus ponderosa Dougl. ex. Laws and mixed-conifer forests of western North America. These extensive montane forests are considered to be adapted to a low/moderate-severity fire regime that maintained stands of relatively old trees. However, there is increasing recognition from landscape-scale assessments that, prior to any significant effects of fire exclusion, fires and forest structure were more variable in these forests. Biota in these forests are also dependent on the resources made available by higher-severity fire. A better understanding of historical fire regimes in the ponderosa pine and mixed-conifer forests of western North America is therefore needed to define reference conditions and help maintain characteristic ecological diversity of these systems. We compiled landscape-scale evidence of historical fire severity patterns in the ponderosa pine and mixed-conifer forests from published literature sources and stand ages available from the Forest Inventory and Analysis program in the USA. The consensus from this evidence is that the traditional reference conditions of low-severity fire regimes are inaccurate for most forests of western North America. Instead, most forests appear to have been characterized by mixed-severity fire that included ecologically significant amounts of weather-driven, high-severity fire. Diverse forests in different stages of succession, with a high proportion in relatively young stages, occurred prior to fire exclusion. Over the past century, successional diversity created by fire decreased. Our findings suggest that ecological management goals that incorporate successional diversity created by fire may support characteristic biodiversity, whereas current attempts to "restore" forests to open, low-severity fire conditions may not align with historical reference conditions in

Examining historical and current mixed-severity fire regimes in ponderosa pine and mixed-conifer forests of western North America.

Science.gov (United States)

Odion, Dennis C; Hanson, Chad T; Arsenault, André; Baker, William L; Dellasala, Dominick A; Hutto, Richard L; Klenner, Walt; Moritz, Max A; Sherriff, Rosemary L; Veblen, Thomas T; Williams, Mark A

2014-01-01

There is widespread concern that fire exclusion has led to an unprecedented threat of uncharacteristically severe fires in ponderosa pine (Pinus ponderosa Dougl. ex. Laws) and mixed-conifer forests of western North America. These extensive montane forests are considered to be adapted to a low/moderate-severity fire regime that maintained stands of relatively old trees. However, there is increasing recognition from landscape-scale assessments that, prior to any significant effects of fire exclusion, fires and forest structure were more variable in these forests. Biota in these forests are also dependent on the resources made available by higher-severity fire. A better understanding of historical fire regimes in the ponderosa pine and mixed-conifer forests of western North America is therefore needed to define reference conditions and help maintain characteristic ecological diversity of these systems. We compiled landscape-scale evidence of historical fire severity patterns in the ponderosa pine and mixed-conifer forests from published literature sources and stand ages available from the Forest Inventory and Analysis program in the USA. The consensus from this evidence is that the traditional reference conditions of low-severity fire regimes are inaccurate for most forests of western North America. Instead, most forests appear to have been characterized by mixed-severity fire that included ecologically significant amounts of weather-driven, high-severity fire. Diverse forests in different stages of succession, with a high proportion in relatively young stages, occurred prior to fire exclusion. Over the past century, successional diversity created by fire decreased. Our findings suggest that ecological management goals that incorporate successional diversity created by fire may support characteristic biodiversity, whereas current attempts to "restore" forests to open, low-severity fire conditions may not align with historical reference conditions in most ponderosa

Distribution of organochlorine pesticides (OCPs) in conifer needles in the southeast Tibetan Plateau

International Nuclear Information System (INIS)

Yang Ruiqiang; Yao Tandong; Xu Baiqing; Jiang Guibin; Zheng Xiaoyan

2008-01-01

Twenty-nine conifer needles in mountain-valley areas from the southeastern Tibet were collected with altitude span from 1520 to 4340 m above sea level (m.a.s.l.). They were analyzed for organochlorine pesticides (OCPs), including hexachlorocyclohexanes (α-, β-, γ- and δ-HCH), dichlorodiphenyltrichloroethane (p,p'-DDE, p,p'-DDD, o,p'-DDT and p,p'-DDT) and hexachlorobenzene (HCB). Concentrations of OCPs in samples ranged from 0.69 to 4.3 ng/g, from 0.39 to 4.9 ng/g and from 1.9 to 20.5 ng/g (dry weight) for HCB, total HCHs and DDTs, respectively. The levels of DDTs found here were noticeably higher than those from other high mountainous regions. Composition of HCH isomers and DDTs was analyzed, and it was found that the high ratio of o,p'-DDT/p,p'-DDT might be caused by the application of dicofol in adjacent regions. A number of environmental factors controlling the distribution of OCPs in regional scale were also discussed in this paper. - Conifer needles in southeastern Tibet indicate several organochlorine pesticides are transported from the Indian continent by the southern Asian monsoon

Fire suppression has led to greater drought-sensitivity in dry conifer forests: tree-ring carbon isotope evidence from Central Oregon

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Voelker, S.; Merschel, A. G.; Meinzer, F. C.; Spies, T. A.; Still, C. J.

2016-12-01

Mortality events of economically and ecologically important conifers have been widespread across Western North America over recent decades. Many of these events have been linked to "global change-type droughts" characterized by greater temperatures and evaporative demand. In parallel, since the early to mid- 20th century, increasing atmospheric [CO2] has been shown to increase the water use efficiency (WUE) of trees worldwide while conifer forests in western North America have become denser after the advent of modern fire suppression efforts. Therefore, competing hypotheses include that conifer forests have experienced 1) less drought stress due to water savings from increased WUE, 2) more drought stress due to increased demand for water in dense forests with greater leaf area index, or 3) unchanging stress because these two factors have cancelled each other out. To provide a test of these hypotheses we used inter-annual latewood carbon isotope discrimination, Δ13C, across a dry mixed-conifer forest landscape of central Oregon in the rain shadow of the Cascade Mountains. The forests are dominated by old-growth ponderosa pines (Pinus ponderosa) and younger and fire-intolerant grand firs (Abies grandis). Dendrochronological dating of tree establishment and fires scars established sharp declines in fire frequency and associated increases in the densities of grand fir since the early 1900s. Δ13C data for ponderosa pine and grand fir spanned 1830-2013 and 1900-2013, respectively. For our analyses these years were split into periods of high fire frequency (1830-1900), moderate fire frequency (1901-1956) and fire-exclusion (1957-2013). Comparisons of Δ13C to reconstructed Palmer Drought Severity Index values for the same years revealed that leaf gas exchange of both species has been more sensitive to drought during the recent fire-exclusion period compared to previous periods when surface fires kept tree densities much lower. Similar research is needed elsewhere to

The ecology and management of moist mixed-conifer forests in eastern Oregon and Washington: a synthesis of the relevant biophysical science and implications for future land management

Science.gov (United States)

Peter Stine; Paul Hessburg; Thomas Spies; Marc Kramer; Christopher J. Fettig; Andrew Hansen; John Lehmkuhl; Kevin O' Hara; Karl Polivka; Peter Singleton; Susan Charnley; Andrew Merschel; Rachel. White

2014-01-01

Land managers in the Pacific Northwest have reported a need for updated scientific information on the ecology and management of mixed-conifer forests east of the Cascade Range in Oregon and Washington. Of particular concern are the moist mixed-conifer forests, which have become drought-stressed and vulnerable to high-severity fire after decades of human disturbances...

Roughness development in electrodeposited soft magnetic CoNiFe films in the presence of organic additives

Directory of Open Access Journals (Sweden)

STEVE RIEMER

2003-05-01

Full Text Available The effects of three additives, sodium lauryl sulfate (NaLS, saccharin (Sacc, and NaLS + Sacc, on roughness development during the electrodeposition of CoNiFe films were investigated. The characterization of these films by atomic force microscopy shows that the electrodeposits produced from NaLS containing solution result in a rough surface. The role of NaLS surfactant is to change the interfacial tension and clean non-polar species like hydrogen bubbles from the surface. In Sacc containing solution, the evolution of a smooth surface is controlled by adsorbed Sacc molecule at the interface. The kinetic roughening of these deposits was investigated by dynamic scaling analysis. It was demonstrated that the roughness of CoNiFe films, obtained in the presence of NaLS + Sacc additives, was also dependent on current density, roughness of substrate, and the temperature of plating bath.

Soil respiration response to prescribed burning and thinning in mixed-conifer and hardwood forests

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Amy Concilio; Siyan Ma; Qinglin Li; James LeMoine; Jiquan Chen; Malcolm North; Daryl Moorhead; Randy Jensen

2005-01-01

The effects of management on soil carbon efflux in different ecosystems are still largely unknown yet crucial to both our understanding and management of global carbon flux. To compare the effects of common forest management practices on soil carbon cycling, we measured soil respiration rate (SRR) in a mixed-conifer and hardwood forest that had undergone various...

Habitats and landscapes associated with bird species in a lowland conifer-dominated ecosystem

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Edmund J. Zlonis

2017-06-01

Full Text Available Human-induced effects on lowland conifer forests in hemiboreal regions are increasing because of expanded use of these northern ecosystems for raw materials, energy, and minerals as well as the potential effects of climatic changes. These forests support many breeding bird species across the Holarctic and allow the persistence of several boreal bird species in hemiboreal and even temperate regions. These bird species are of particular conservation concern as shifting patterns northward in forest composition caused by climate change will likely affect their populations. However, effective management and conservation options are limited because the specifics of these species' breeding habitats are not well understood. We modeled and mapped habitat suitability for 11 species of boreal birds that breed in the lowland conifer forests of the Agassiz Lowlands Ecological Subsection in northern Minnesota and are likely to have reduced breeding habitat in the future: Spruce Grouse (Falcipennis canadensis, Black-backed Woodpecker (Picoides arcticus, Olive-sided Flycatcher (Contopus cooperi, Yellow-bellied Flycatcher (Empidonax flaviventris, Boreal Chickadee (Poecile hudsonicus, Golden-crowned Kinglet (Regulus satrapa, Ruby-crowned Kinglet (Regulus calendula, Swainson's Thrush (Catharus ustulatus, Connecticut Warbler (Oporornis agilis, Palm Warbler (Setophaga palmarum, and Dark-eyed Junco (Junco hyemalis. Sets of 7 to 16 potential environmental covariates, including both stand-level and landscape attributes, were used to develop individual species models. Within this lowland conifer-dominated ecosystem, we found significant selection for specific forest and landscape characteristics by all but one of these species, with the best models including between one and nine variables. Habitat suitability maps were developed from these models and predictions tested with an independent dataset. Model performance depended on species, correctly predicting 56-96% of

Regeneration in mixed conifer and Douglas-fir shelterwood cuttings in the Cascade Range of Washington.

Science.gov (United States)

K.W. Seidel

1983-01-01

A survey of shelterwood cuttings in mixed conifer and Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) forests in the Cascade Range in Washington showed that, on the average, shelterwood units were adequately-stocked with a mixture of advance, natural postharvest, and planted reproduction of a number of species. Shelterwood cuttings in the...

Cold in the common garden: comparative low-temperature tolerance of boreal and temperate conifer foliage

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G. Richard Strimbeck; Trygve D. Kjellsen; Paul G. Schaberg; Paula F. Murakami

2007-01-01

Because they maintain green foliage throughout the winter season, evergreen conifers may face special physiological challenges in a warming world. We assessed the midwinter low-temperature (LT) tolerance of foliage from eight temperate and boreal species in each of the genera Abies, Picea, and Pinus growing in an arboretum in...

Terrain and vegetation structural influences on local avian species richness in two mixed-conifer forests

Science.gov (United States)

Jody C. Vogeler; Andrew T. Hudak; Lee A. Vierling; Jeffrey Evans; Patricia Green; Kerri T. Vierling

2014-01-01

Using remotely-sensed metrics to identify regions containing high animal diversity and/or specific animal species or guilds can help prioritize forest management and conservation objectives across actively managed landscapes. We predicted avian species richness in two mixed conifer forests, Moscow Mountain and Slate Creek, containing different management contexts and...

Investigation on the Assimilation of Nitrogen by Maize Roots and the Transport of Some Major Nitrogen Compounds by Xylem Sap. III

DEFF Research Database (Denmark)

Ivanko, S.; Ingversen, J.

1971-01-01

Xylem sap was collected from nitrogen-starved maize plants and investigations were made on the nitrogen transported. It appears from the results that several pools for different amino acids exist, which have different relations to the transport of nitrogen taken up. While in maize roots Glu, Glu...

A Mixed-Effects Heterogeneous Negative Binomial Model for Postfire Conifer Regeneration in Northeastern California, USA

Science.gov (United States)

Justin S. Crotteau; Martin W. Ritchie; J. Morgan. Varner

2014-01-01

Many western USA fire regimes are typified by mixed-severity fire, which compounds the variability inherent to natural regeneration densities in associated forests. Tree regeneration data are often discrete and nonnegative; accordingly, we fit a series of Poisson and negative binomial variation models to conifer seedling counts across four distinct burn severities and...

Aboveground and belowground mammalian herbivores regulate the demography of deciduous woody species in conifer forests

Science.gov (United States)

Bryan A. Endress; Bridgett J. Naylor; Burak K. Pekin; Michael J. Wisdom

2016-01-01

Mammalian herbivory can have profound impacts on plant population and community dynamics. However, our understanding of specific herbivore effects remains limited, even in regions with high densities of domestic and wild herbivores, such as the semiarid conifer forests of western North America. We conducted a seven-year manipulative experiment to evaluate the effects...

Dynamics of low-temperature acclimation in temperate and boreal conifer foliage in a mild winter climate

Science.gov (United States)

G. Richard Strimbeck; Trygve D. Kjellsen; Paul G. Schaberg; Paula F. Murakami

2008-01-01

To provide baseline data for physiological studies of extreme low-temperature (LT) tolerance in boreal conifers, we profiled LT stress responses, liquid nitrogen (LN2)-quench tolerance, and sugar concentrations in foliage of boreal-temperate species pairs in the genera Abies, Picea and Pinus, growing in an...

Foliar responses of understorey Abies lasiocarpa to different degrees of release cutting of Betula papyrifera and conifer mixed species stand

Energy Technology Data Exchange (ETDEWEB)

Wang, J.R.; Letchford, T. [Ministry of Forests, Prince George, BC (Canada). Red Rock Research Station; Comeau, P.G. [BC Ministry of Forests, Victoria, BC (Canada); Coopersmith, D. [BC Ministry of Forests, Prince George, BC (Canada)

2000-07-01

Foliar responses of subalpine fir (Abies lasiocarpa (Hook.) Nutt.) to thinning were studied in a 35-yr-old mixed stand of paper birch (Betula papyrifera Marsh.) and conifers. The stand regenerated naturally after a wildfire with a canopy dominated by paper birch (average height 9.8 m) and an understorey dominated by subalpine fir (average height 1.6 m). The stand was thinned to four densities of birch: 0, 600 and 1200 stems ha{sup -1} and control (Unthinned at 2300-6400 stems ha{sup -1}) in the autumn of 1995. The understorey conifers, mainly subalpine fir, were thinned to 1200 stems ha{sup -1}. The study used a completely randomized split-plot design. Three sample trees were systematically selected from each treatment replicate and each tree stratum (upper, intermediate and lower understorey). One-year-old and older age class needles were collected from one south-facing branch within the fifth whorl from the tree top. Thinning of paper birch significantly (p<0.001) increased leaf area and dry weight per 100 needles for intermediate and short trees except in the 0 birch treatment. Understorey subalpine fir trees in 600 stems ha{sup -1} birch (T3) had the largest leaf area and leaf dry weight per 100 1-yr-old needles. Specific leaf area (SLA) decreased from unthinned (T1) to 0 birch (T4). Lower understorey trees had the largest SLA. One-year-old needles had significantly higher N, P and K concentrations in all the thinning treatments. These responses are consistent with the shade tolerance of subalpine fir. The results suggest that when managing a paper birch-conifers mixed wood forest it may be of benefit to understorey conifers to leave a birch canopy as a nursing crop.

Radiation exposure near Chernobyl based on analysis of conifer injury using thematic mapper satellite images

International Nuclear Information System (INIS)

Goldman, M.; Ustin, S.L.; Sadowski, F.G.

1988-01-01

Radiation-induced damage in conifers adjacent to the damaged Chernobyl nuclear power plant has been evaluated using LANDSAT Thematic Mapper (TM) satellite images. Eight images acquired between 22 April 1986 and 15 May 1987 were used to assess the extent and magnitude of radiation effects on pine trees within 10 km of the reactor site. The timing and spatial extent of vegetation damaged was used to estimate the radiation doses in the near field around the Chernobyl nuclear power station and to indirectly derive the dose rates as a function of time during and after the accident. A normalized vegetation index was developed from the TM band data to visually demonstrate the damage and mortality to nearby conifer stands. The patterns of spectral change indicative of vegetation stress are consistent with changes expected for radiation injury and mortality. The extent and timing of these effects permitted the development of an integrated dose estimate, which was combined with the information regarding the characteristics of radionuclide mix, to provide an estimate of maximum dose rates during the early period of the accident. The derived peak dose rates during the 10-day release in the accident are high and are estimated at about 0.5 to 1 rad per hour. These are not considered life-threatening and would therefore require prompt but not immediate evacuation; that is, no off-site fatalities would be likely under such conditions. The methodology employed to combine remote-sensing analyses and the estimates of source term release with the known radiation effects on conifers represent a unique integration of these scientific and technical tools. The results of the study show that remote-sensing techniques can be used to develop a quantitative methodology for dosimetric applications and for future monitoring activities related to reactor safety

Data set on the effects of conifer control and slash burning on soil carbon, total N, organic matter and extractable micro-nutrients

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Jonathan D. Bates

2017-10-01

Full Text Available Conifer control in sagebrush steppe of the western United States causes various levels of site disturbance influencing vegetation recovery and resource availability. The data set presented in this article include growing season availability of soil micronutrients and levels of total soil carbon, organic matter, and N spanning a six year period following western juniper (Juniperus occidentalis spp. occidentalis reduction by mechanical cutting and prescribed fire of western juniper woodlands in southeast Oregon. These data can be useful to further evaluate the impacts of conifer woodland reduction to soil resources in sagebrush steppe plant communities.

Effects of Fe and Mn deficiencies on the protein profiles of tomato (Solanum lycopersicum) xylem sap as revealed by shotgun analyses

Science.gov (United States)

The aim of this work was to study the effects of Fe and Mn deficiencies on the xylem sap proteome of tomato using a shotgun proteomic approach, with the final goal of elucidating plant response mechanisms to these stresses. This approach yielded 643 proteins reliably identified and quantified with 7...

Bordered pit structure and function determine spatial patterns of air-seeding thresholds in xylem of Douglas-fir (Pseudotsuga menziesii; Pinaceae) trees.

Science.gov (United States)

J.C. Domec; B. Lachenbruch; F.C. Meinzer

2006-01-01

The air-seeding hypothesis predicts that xylem embolism resistance is linked directly to bordered pit functioning. We tested this prediction in trunks, roots, and branches at different vertical and radial locations in young and old trees of Pseudotsuga menziesii. Dimensions of bordered pits were measured from light and scanning electron micrographs...

Tyloses and phenolic deposits in xylem vessels impede water transport in low-lignin transgenic poplars: a study by cryo-fluorescence microscopy

Science.gov (United States)

Peter Kitin; Steven L. Voelker; Frederick C. Meinzer; Hans Beekman; Steven H. Strauss; Barbara. Lachenbruch

2010-01-01

Of 14 transgenic poplar genotypes (Populus tremula x Populus alba) with antisense 4-coumarate:coenzynle A ligase that were grown in the field for 2 years, five that had substantial lignin reductions also had greatly reduced xylem-specific conductivity compared with that of control trees and those transgenic events with small...

Hydraulic safety margins and embolism reversal in stems and leaves: Why are conifers and angiosperms so different?

Science.gov (United States)

Daniel M. Johnson; Katherine A. McCulloh; David R. Woodruff; Frederick C. Meinzer

2012-01-01

Angiosperm and coniferous tree species utilize a continuum of hydraulic strategies. Hydraulic safety margins (defined as differences between naturally occurring xylem pressures and pressures that would cause hydraulic dysfunction, or differences between pressures resulting in loss of hydraulic function in adjacent organs (e.g., stems vs. leaves) tend to be much greater...

Structure, specificity, and evolution of insect guilds related to cones of conifers in Western Europe

Science.gov (United States)

Alain Roques

1991-01-01

Patchy and ephemeral resources, such as the cones of conifers, can be very useful in the study of plant-insect relationships. Studies of such relationships in forest entomology are typically complicated by the spatial and temporal characteristics of the host plants, which occur over vast areas and have lifespans of decades or even centuries. The reproductive structures...

Application of point-process statistical tools to stable isotopes in xylem water for the study of inter- and intra-specific interactions in water uptake patterns in a mixed stand of Pinus halepensis Mill. and Quercus ilex L.

Science.gov (United States)

Comas, Carles; del Castillo, Jorge; Voltas, Jordi; Ferrio, Juan Pedro

2013-04-01

The stable isotope composition of xylem water reflects has been used to assess inter-specific differences in uptake patterns, revealing synergistic and competition processes in the use of water resources (see e.g. Dawson et al. 1993). However, there is a lack of detailed studies on spatial and temporal variability of inter- and intra-specific competition within forest stands. In this context, the aim of this work was to compare the isotope composition of xylem water (δ18O , δ2H) in two common Mediterranean tree species, Quercus ilex L. and Pinus halepensis Mill, in order to understand their water uptake patterns throughout the growing season. In addition, we analyze the spatial variability of xylem water, to get insight into inter-specific strategies employed to cope with drought and the interaction between the individuals. Our first hypothesis was that both species used different strategies to cope with drought by uptaking water at different depths; and our second hypothesis was that individual trees would behave in different manner according to the distance to their neighbours as well as to whether the neighbour is from one species or the other. The study was performed in a mixed stand where both species are nearly co-dominant, adding up to a total of 33 oaks and 77 pines (plot area= 893 m2). We sampled sun-exposed branches of each tree six times over the growing season, and extracted the xylem water with a cryogenic trap. The isotopic composition of the water was determined using a Picarro Water Analizer L2130-i. Tree mapping for spatial analysis was done using a high resolution GPS technology (Trimble GeoExplorer 6000). For the spatial analysis, we used the pair-correlation function to study intra-specific tree configuration and the bivariate pair correlation function to analyse the inter-specific spatial configurations (Stoyan et al 1995). Moreover, the isotopic composition of xylem water was assumed to be a mark associated to each tree and analysed as a

Variability of Cenococcum colonization and its ecophysiological significance for young conifers at alpine-treeline.

Science.gov (United States)

Hasselquist, Niles; Germino, Matthew J; McGonigle, Terence; Smith, William K

2005-03-01

* Plants establishing in environments that are marginal for growth could be particularly sensitive to mycorrhizal associations. We investigated ectomycorrhizal colonization and its significance for young conifers growing at, or above, their normal limits for growth, in the alpine-treeline ecotone. * Colonization of seedlings (treeline may include a below-ground, mycorrhizal component that complements previously reported effects of trees on the microclimate and ecophysiology of seedlings.

Contrasting spatial patterns in active-fire and fire-suppressed Mediterranean climate old-growth mixed conifer forests

Science.gov (United States)

Danny L. Fry; Scott L. Stephens; Brandon M. Collins; Malcolm North; Ernesto Franco-Vizcaino; Samantha J. Gill

2014-01-01

In Mediterranean environments in western North America, historic fire regimes in frequent-fire conifer forests are highly variable both temporally and spatially. This complexity influenced forest structure and spatial patterns, but some of this diversity has been lost due to anthropogenic disruption of ecosystem processes, including fire. Information from reference...

Specific Fluorescence in Situ Hybridization (FISH) Test to Highlight Colonization of Xylem Vessels by Xylella fastidiosa in Naturally Infected Olive Trees (Olea europaea L.)

Science.gov (United States)

Cardinale, Massimiliano; Luvisi, Andrea; Meyer, Joana B.; Sabella, Erika; De Bellis, Luigi; Cruz, Albert C.; Ampatzidis, Yiannis; Cherubini, Paolo

2018-01-01

The colonization behavior of the Xylella fastidiosa strain CoDiRO, the causal agent of olive quick decline syndrome (OQDS), within the xylem of Olea europaea L. is still quite controversial. As previous literature suggests, even if xylem vessel occlusions in naturally infected olive plants were observed, cell aggregation in the formation of occlusions had a minimal role. This observation left some open questions about the whole behavior of the CoDiRO strain and its actual role in OQDS pathogenesis. In order to evaluate the extent of bacterial infection in olive trees and the role of bacterial aggregates in vessel occlusions, we tested a specific fluorescence in situ hybridization (FISH) probe (KO 210) for X. fastidiosa and quantified the level of infection and vessel occlusion in both petioles and branches of naturally infected and non-infected olive trees. All symptomatic petioles showed colonization by X. fastidiosa, especially in the larger innermost vessels. In several cases, the vessels appeared completely occluded by a biofilm containing bacterial cells and extracellular matrix and the frequent colonization of adjacent vessels suggested a horizontal movement of the bacteria. Infected symptomatic trees had 21.6 ± 10.7% of petiole vessels colonized by the pathogen, indicating an irregular distribution in olive tree xylem. Thus, our observations point out the primary role of the pathogen in olive vessel occlusions. Furthermore, our findings indicate that the KO 210 FISH probe is suitable for the specific detection of X. fastidiosa. PMID:29681910

Application of TXRF spectrometry and HPLC for the characterization of xylem saps of nickel contaminated cucumber plants grown in urea containing nutrient solutions

International Nuclear Information System (INIS)

Tatar, E.; Mihucz, V.G.; Varga, G.; Zaray, G.; Cseh, E.

2000-01-01

The total reflection X-ray fluorescence (TXRF) spectrometry was used to determine the elemental composition of xylem saps of cucumber plants grown in nutrient solutions having urea, as the sole nitrogen source and artificially contaminated with nickel(II) ions in concentration of 10 μM, which proved to be toxic for the plants. The saps of uncontaminated plants - grown at the same time with the contaminated ones - were also investigated. The collection of the samples was performed for 1 hour followed by two additional 30-minute-long time periods, thus three samples resulted for each group of plants. The TXRF measurements were performed using Ga as internal standard. For excitation, Mo tube was used and the integration time was 300 s. The nutrient heavy metals determined by the TXRF spectrometry in the saps were Fe, Mn and Zn in concentration range of ng/cm 3 . Two other nutrient elements, Ca and K were also determined and they were present in the samples in concentration of μg/cm 3 . The concentration of nickel in the saps originating from the contaminated plants, was approximately 1400 ng/cm 3 . The concentration of another nutrient heavy metal, Cu was determined by the graphite furnace atomic absorption (GF-AAS) spectrometry. Applying a reversed-phased HPLC method, the organic acids of the samples, citric, malic and fumaric acids were also quantified, their concentrations being also in the μg/cm 3 concentration range. Size exclusion chromatography (SEC) measurements were also performed in order to detect possible macromolecules of the saps. Both techniques, having low sample volume demand, were suitable to perform reliable measurements of the samples whose masses were between 0,9-2,5 g. Furthermore, the absence of the matrix effects is also an important advantage of the TXRF spectrometry that permits the direct analysis of the xylem saps. These investigations form part of our work focusing on the availability, accumulation and transport of heavy metals in

Drought resistance in early and late secondary successional species from a tropical dry forest: the interplay between xylem resistance to embolism, sapwood water storage and leaf shedding.

Science.gov (United States)

Pineda-García, Fernando; Paz, Horacio; Meinzer, Frederick C

2013-02-01

The mechanisms of drought resistance that allow plants to successfully establish at different stages of secondary succession in tropical dry forests are not well understood. We characterized mechanisms of drought resistance in early and late-successional species and tested whether risk of drought differs across sites at different successional stages, and whether early and late-successional species differ in resistance to experimentally imposed soil drought. The microenvironment in early successional sites was warmer and drier than in mature forest. Nevertheless, successional groups did not differ in resistance to soil drought. Late-successional species resisted drought through two independent mechanisms: high resistance of xylem to embolism, or reliance on high stem water storage capacity. High sapwood water reserves delayed the effects of soil drying by transiently decoupling plant and soil water status. Resistance to soil drought resulted from the interplay between variations in xylem vulnerability to embolism, reliance on sapwood water reserves and leaf area reduction, leading to a tradeoff of avoidance against tolerance of soil drought, along which successional groups were not differentiated. Overall, our data suggest that ranking species' performance under soil drought based solely on xylem resistance to embolism may be misleading, especially for species with high sapwood water storage capacity. © 2012 Blackwell Publishing Ltd.

Dynamics of leaf gas exchange, xylem and phloem transport, water potential and carbohydrate concentration in a realistic 3-D model tree crown.

Science.gov (United States)

Nikinmaa, Eero; Sievänen, Risto; Hölttä, Teemu

2014-09-01

Tree models simulate productivity using general gas exchange responses and structural relationships, but they rarely check whether leaf gas exchange and resulting water and assimilate transport and driving pressure gradients remain within acceptable physical boundaries. This study presents an implementation of the cohesion-tension theory of xylem transport and the Münch hypothesis of phloem transport in a realistic 3-D tree structure and assesses the gas exchange and transport dynamics. A mechanistic model of xylem and phloem transport was used, together with a tested leaf assimilation and transpiration model in a realistic tree architecture to simulate leaf gas exchange and water and carbohydrate transport within an 8-year-old Scots pine tree. The model solved the dynamics of the amounts of water and sucrose solute in the xylem, cambium and phloem using a fine-grained mesh with a system of coupled ordinary differential equations. The simulations predicted the observed patterns of pressure gradients and sugar concentration. Diurnal variation of environmental conditions influenced tree-level gradients in turgor pressure and sugar concentration, which are important drivers of carbon allocation. The results and between-shoot variation were sensitive to structural and functional parameters such as tree-level scaling of conduit size and phloem unloading. Linking whole-tree-level water and assimilate transport, gas exchange and sink activity opens a new avenue for plant studies, as features that are difficult to measure can be studied dynamically with the model. Tree-level responses to local and external conditions can be tested, thus making the approach described here a good test-bench for studies of whole-tree physiology.

Broadband, red-edge information from satellites improves early stress detection in a New Mexico conifer woodland

Science.gov (United States)

Jan U.H. Eitel; Lee A. Vierling; Marcy E. Litvak; Dan S. Long; Urs Schulthess; Alan A. Ager; Dan J. Krofcheck; Leo Stoscheck

2011-01-01

Multiple plant stresses can affect the health, esthetic condition, and timber harvest value of conifer forests. To monitor spatial and temporal dynamic forest stress conditions, timely, accurate, and cost-effective information is needed that could be provided by remote sensing. Recently, satellite imagery has become available via the RapidEye satellite constellation to...

Post-fire management regimes affect carbon sequestration and storage in a Sierra Nevada mixed conifer forest

Science.gov (United States)

Elizabeth M. Powers; John D. Marshall; Jianwei Zhang; Liang Wei

2013-01-01

Forests mitigate climate change by sequestering CO2 from the atmosphere and accumulating it in biomass storage pools. However, in dry conifer forests, fire occasionally returns large quantities of CO2 to the atmosphere. Both the total amount of carbon stored and its susceptibility to loss may be altered by post-fire land...

Plasticity in physiological traits in conifers: Implications for response to climate change in the western U.S

International Nuclear Information System (INIS)

Grulke, N.E.

2010-01-01

Population variation in ecophysiological traits of four co-occurring montane conifers was measured on a large latitudinal gradient to quantitatively assess their potential for response to environmental change. White fir (Abies concolor) had the highest variability, gross photosynthetic rate (Pg), and foliar carbon (C) and nitrogen (N) content. Despite low water use efficiency (WUE), stomatal conductance (gs) of fir was the most responsive to unfavorable environmental conditions. Pinus lambertiana exhibited the least variability in Pg and WUE, and is likely to be the most vulnerable to environmental changes. Pinus ponderosa had an intermediate level of variability, and high needle growth at its higher elevational limits. Pinus Jeffreyi also had intermediate variability, but high needle growth at its southern latitudinal and lower elevational limits. The attributes used to assess tree vigor were effective in predicting population vulnerability to abiotic (drought) and biotic (herbivore) stresses. - Variability in ecophysiological attributes of western U.S. conifers suggests relative capacity of species and populations to respond to environmental change.

Plasticity in physiological traits in conifers: Implications for response to climate change in the western U.S

Energy Technology Data Exchange (ETDEWEB)

Grulke, N.E., E-mail: ngrulke@fs.fed.u [Pacific Southwest Research Station, USDA Forest Service, 4955 Canyon Crest Drive, Riverside, CA 92507 (United States)

2010-06-15

Population variation in ecophysiological traits of four co-occurring montane conifers was measured on a large latitudinal gradient to quantitatively assess their potential for response to environmental change. White fir (Abies concolor) had the highest variability, gross photosynthetic rate (Pg), and foliar carbon (C) and nitrogen (N) content. Despite low water use efficiency (WUE), stomatal conductance (gs) of fir was the most responsive to unfavorable environmental conditions. Pinus lambertiana exhibited the least variability in Pg and WUE, and is likely to be the most vulnerable to environmental changes. Pinus ponderosa had an intermediate level of variability, and high needle growth at its higher elevational limits. Pinus Jeffreyi also had intermediate variability, but high needle growth at its southern latitudinal and lower elevational limits. The attributes used to assess tree vigor were effective in predicting population vulnerability to abiotic (drought) and biotic (herbivore) stresses. - Variability in ecophysiological attributes of western U.S. conifers suggests relative capacity of species and populations to respond to environmental change.

Short Communication. Comparing flammability traits among fire-stricken (low elevation) and non fire-stricken (high elevation) conifer forest species of Europe: A test of the Mutch hypothesis

OpenAIRE

A. P. Dimitrakopoulos; I. D. Mitsopoulos; A. Kaliva

2013-01-01

Aim of study. The flammability of the main coniferous forest species of Europe, divided into two groups according to their fire regime and altitudinal distribution, was tested in an effort to detect species-specific differences that may have an influence on community-wide fire regimes.Area of study. Conifer species comprising low- and high-elevation forests in Europe.Materials and Methods. The following conifer species were tested: low elevation; Pinus halepensis (Aleppo pine), Pinus brutia (...

Ectomycorrhizal sporophore distributions in a southeastern Appalachian mixed hardwood/conifer forest with thickets of Rhododendron maximum

Science.gov (United States)

John F. Walker; Orson R. Jr. Miller

2002-01-01

Sporophore abundance of putatively ectomycorrhizal fungi was compared in a mature mixed hardwood/conifer forest inside of (1) versus outside of (2) Rhododendron maximum thickets (RmT). Experimental blocks (1/4 ha) were established inside of (3) and outside of (3) RmT at the Coweeta Hydrologic Laboratory in Macon County, North Carolina, USA. Litter...

A structurally based analytic model of growth and biomass dynamics in single species stands of conifers

Science.gov (United States)

Robin J. Tausch

2015-01-01

A theoretically based analytic model of plant growth in single species conifer communities based on the species fully occupying a site and fully using the site resources is introduced. Model derivations result in a single equation simultaneously describes changes over both, different site conditions (or resources available), and over time for each variable for each...

Genomic insights into strategies used by Xanthomonas albilineans with its reduced artillery to spread within sugarcane xylem vessels

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Pieretti Isabelle

2012-11-01

Full Text Available Abstract Background Xanthomonas albilineans causes leaf scald, a lethal disease of sugarcane. X. albilineans exhibits distinctive pathogenic mechanisms, ecology and taxonomy compared to other species of Xanthomonas. For example, this species produces a potent DNA gyrase inhibitor called albicidin that is largely responsible for inducing disease symptoms; its habitat is limited to xylem; and the species exhibits large variability. A first manuscript on the complete genome sequence of the highly pathogenic X. albilineans strain GPE PC73 focused exclusively on distinctive genomic features shared with Xylella fastidiosa—another xylem-limited Xanthomonadaceae. The present manuscript on the same genome sequence aims to describe all other pathogenicity-related genomic features of X. albilineans, and to compare, using suppression subtractive hybridization (SSH, genomic features of two strains differing in pathogenicity. Results Comparative genomic analyses showed that most of the known pathogenicity factors from other Xanthomonas species are conserved in X. albilineans, with the notable absence of two major determinants of the “artillery” of other plant pathogenic species of Xanthomonas: the xanthan gum biosynthesis gene cluster, and the type III secretion system Hrp (hypersensitive response and pathogenicity. Genomic features specific to X. albilineans that may contribute to specific adaptation of this pathogen to sugarcane xylem vessels were also revealed. SSH experiments led to the identification of 20 genes common to three highly pathogenic strains but missing in a less pathogenic strain. These 20 genes, which include four ABC transporter genes, a methyl-accepting chemotaxis protein gene and an oxidoreductase gene, could play a key role in pathogenicity. With the exception of hypothetical proteins revealed by our comparative genomic analyses and SSH experiments, no genes potentially involved in any offensive or counter-defensive mechanism

DNA barcoding the native flowering plants and conifers of Wales.

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Natasha de Vere

Full Text Available We present the first national DNA barcode resource that covers the native flowering plants and conifers for the nation of Wales (1143 species. Using the plant DNA barcode markers rbcL and matK, we have assembled 97.7% coverage for rbcL, 90.2% for matK, and a dual-locus barcode for 89.7% of the native Welsh flora. We have sampled multiple individuals for each species, resulting in 3304 rbcL and 2419 matK sequences. The majority of our samples (85% are from DNA extracted from herbarium specimens. Recoverability of DNA barcodes is lower using herbarium specimens, compared to freshly collected material, mostly due to lower amplification success, but this is balanced by the increased efficiency of sampling species that have already been collected, identified, and verified by taxonomic experts. The effectiveness of the DNA barcodes for identification (level of discrimination is assessed using four approaches: the presence of a barcode gap (using pairwise and multiple alignments, formation of monophyletic groups using Neighbour-Joining trees, and sequence similarity in BLASTn searches. These approaches yield similar results, providing relative discrimination levels of 69.4 to 74.9% of all species and 98.6 to 99.8% of genera using both markers. Species discrimination can be further improved using spatially explicit sampling. Mean species discrimination using barcode gap analysis (with a multiple alignment is 81.6% within 10×10 km squares and 93.3% for 2×2 km squares. Our database of DNA barcodes for Welsh native flowering plants and conifers represents the most complete coverage of any national flora, and offers a valuable platform for a wide range of applications that require accurate species identification.

Line-scan inspection of conifer seedlings

Science.gov (United States)

Rigney, Michael P.; Kranzler, Glenn A.

1993-05-01

Almost two billion conifer seedlings are produced in the U.S. each year to support reforestation efforts. Seedlings are graded manually to improve viability after transplanting. Manual grading is labor-intensive and subject to human variability. Our previous research demonstrated the feasibility of automated tree seedling inspection with machine vision. Here we describe a system based on line-scan imaging, providing a three-fold increase in resolution and inspection rate. A key aspect of the system is automatic recognition of the seedling root collar. Root collar diameter, shoot height, and projected shoot and root areas are measured. Sturdiness ratio and shoot/root ratio are computed. Grade is determined by comparing measured features with pre-defined set points. Seedlings are automatically sorted. The precision of machine vision and manual measurements was determined in tests at a commercial forest nursery. Manual measurements of stem diameter, shoot height, and sturdiness ratio had standard deviations three times those of machine vision measurements. Projected shoot area was highly correlated (r2 equals 0.90) with shoot volume. Projected root area had good correlation (r2 equals 0.80) with root volume. Seedlings were inspected at rates as high as ten per second.

Evaluation of sampling methods to quantify abundance of hardwoods and snags within conifer-dominated riparian zones

Science.gov (United States)

Theresa Marquardt; Hailemariam Temesgen; Paul D. Anderson; Bianca. Eskelson

2012-01-01

Six sampling alternatives were examined for their ability to quantify selected attributes of snags and hardwoods in conifer-dominated riparian areas of managed headwater forests in western Oregon. Each alternative was simulated 500 times at eight headwater forest locations based on a 0.52-ha square stem map. The alternatives were evaluated based on how well they...

Biophysical controls on soil respiration in the dominant patch types of an old-growth, mixed-conifer forest

Science.gov (United States)

Siyan Ma; Jiquan Chen; John R. Butnor; Malcolm North; Eugénie S. Euskirchen; Brian Oakley

2005-01-01

Little is known about biophysical controls on soil respiration in California's Sierra Nevada old-growth, mixed-conifer forests. Using portable and automated soil respiration sampling units, we measured soil respiration rate (SRR) in three dominant patch types: closed canopy (CC), ceanothus-dominated patches (CECO), and open canopy (OC). SRR varied significantly...

Generation and analysis of expressed sequence tags from six developing xylem libraries in Pinus radiata D. Don

Directory of Open Access Journals (Sweden)

Dillon Shannon K

2009-01-01

Full Text Available Abstract Background Wood is a major renewable natural resource for the timber, fibre and bioenergy industry. Pinus radiata D. Don is the most important commercial plantation tree species in Australia and several other countries; however, genomic resources for this species are very limited in public databases. Our primary objective was to sequence a large number of expressed sequence tags (ESTs from genes involved in wood formation in radiata pine. Results Six developing xylem cDNA libraries were constructed from earlywood and latewood tissues sampled at juvenile (7 yrs, transition (11 yrs and mature (30 yrs ages, respectively. These xylem tissues represent six typical development stages in a rotation period of radiata pine. A total of 6,389 high quality ESTs were collected from 5,952 cDNA clones. Assembly of 5,952 ESTs from 5' end sequences generated 3,304 unigenes including 952 contigs and 2,352 singletons. About 97.0% of the 5,952 ESTs and 96.1% of the unigenes have matches in the UniProt and TIGR databases. Of the 3,174 unigenes with matches, 42.9% were not assigned GO (Gene Ontology terms and their functions are unknown or unclassified. More than half (52.1% of the 5,952 ESTs have matches in the Pfam database and represent 772 known protein families. About 18.0% of the 5,952 ESTs matched cell wall related genes in the MAIZEWALL database, representing all 18 categories, 91 of all 174 families and possibly 557 genes. Fifteen cell wall-related genes are ranked in the 30 most abundant genes, including CesA, tubulin, AGP, SAMS, actin, laccase, CCoAMT, MetE, phytocyanin, pectate lyase, cellulase, SuSy, expansin, chitinase and UDP-glucose dehydrogenase. Based on the PlantTFDB database 41 of the 64 transcription factor families in the poplar genome were identified as being involved in radiata pine wood formation. Comparative analysis of GO term abundance revealed a distinct transcriptome in juvenile earlywood formation compared to other stages of

Remote sensing of fire severity: linking post-fire reflectance data with physiological responses in two western conifer species

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Sparks, A. M.; Smith, A. M.; Kolden, C.; Apostol, K. G.; Boschetti, L.

2014-12-01

Fire is a common disturbance in forested ecosystems in the western U.S. and can be responsible for long-term impacts on vegetation and soil. An improved understanding of how ecosystems recover after fire is necessary so that land managers can plan for and mitigate the effects of these disturbances. Although several studies have attempted to link fire intensity with severity, direct links between spectral indices of severity and key physiological changes in vegetation are not well understood. We conducted an assessment of how two western conifer species respond to four fire radiative energy treatments, with spectra acquired pre- and up to a month post-burn. After transforming the spectral data into Landsat 8 equivalent reflectance, burn severity indices commonly used in the remote sensing community were compared to concurrent physiological measurements including gas exchange and photosynthetic rate. Preliminary results indicate significant relationships between several fire severity indices and physiological responses measured in the conifer seedlings.

Conifer Diterpene Resin Acids Disrupt Juvenile Hormone-Mediated Endocrine Regulation in the Indian Meal Moth Plodia interpunctella.

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Oh, Hyun-Woo; Yun, Chan-Seok; Jeon, Jun Hyoung; Kim, Ji-Ae; Park, Doo-Sang; Ryu, Hyung Won; Oh, Sei-Ryang; Song, Hyuk-Hwan; Shin, Yunhee; Jung, Chan Sik; Shin, Sang Woon

2017-07-01

Diterpene resin acids (DRAs) are important components of oleoresin and greatly contribute to the defense strategies of conifers against herbivorous insects. In the present study, we determined that DRAs function as insect juvenile hormone (JH) antagonists that interfere with the juvenile hormone-mediated binding of the JH receptor Methoprene-tolerant (Met) and steroid receptor coactivator (SRC). Using a yeast two-hybrid system transformed with Met and SRC from the Indian meal moth Plodia interpunctella, we tested the interfering activity of 3704 plant extracts against JH III-mediated Met-SRC binding. Plant extracts from conifers, especially members of the Pinaceae, exhibited strong interfering activity, and four active interfering DRAs (7α-dehydroabietic acid, 7-oxodehydroabietic acid, dehydroabietic acid, and sandaracopimaric acid) were isolated from roots of the Japanese pine Pinus densiflora. The four isolated DRAs, along with abietic acid, disrupted the juvenile hormone-mediated binding of P. interpunctella Met and SRC, although only 7-oxodehydroabietic acid disrupted larval development. These results demonstrate that DRAs may play a defensive role against herbivorous insects via insect endocrine-disrupting activity.

First insights into the functional role of vasicentric tracheids and parenchyma in eucalyptus species with solitary vessels: do they contribute to xylem efficiency or safety?

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Barotto, Antonio José; Fernandez, María Elena; Gyenge, Javier; Meyra, Ariel; Martinez-Meier, Alejandro; Monteoliva, Silvia

2016-12-01

The relationship between hydraulic specific conductivity (k s ) and vulnerability to cavitation (VC) with size and number of vessels has been studied in many angiosperms. However, few of the studies link other cell types (vasicentric tracheids (VT), fibre-tracheids, parenchyma) with these hydraulic functions. Eucalyptus is one of the most important genera in forestry worldwide. It exhibits a complex wood anatomy, with solitary vessels surrounded by VT and parenchyma, which could serve as a good model to investigate the functional role of the different cell types in xylem functioning. Wood anatomy (several traits of vessels, VT, fibres and parenchyma) in conjunction with maximum k s and VC was studied in adult trees of commercial species with medium-to-high wood density (Eucalyptus globulus Labill., Eucalyptus viminalis Labill. and Eucalyptus camaldulensis Dehnh.). Traits of cells accompanying vessels presented correlations with functional variables suggesting that they contribute to both increasing connectivity between adjacent vessels-and, therefore, to xylem conduction efficiency-and decreasing the probability of embolism propagation into the tissue, i.e., xylem safety. All three species presented moderate-to-high resistance to cavitation (mean P 50 values = -2.4 to -4.2 MPa) with no general trade-off between efficiency and safety at the interspecific level. The results in these species do not support some well-established hypotheses of the functional meaning of wood anatomy. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Modeling climate and fuel reduction impacts on mixed-conifer forest carbon stocks in the Sierra Nevada, California

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Matthew D. Hurteau; Timothy A. Robards; Donald Stevens; David Saah; Malcolm North; George W. Koch

2014-01-01

Quantifying the impacts of changing climatic conditions on forest growth is integral to estimating future forest carbon balance. We used a growth-and-yield model, modified for climate sensitivity, to quantify the effects of altered climate on mixed-conifer forest growth in the Lake Tahoe Basin, California. Estimates of forest growth and live tree carbon stocks were...

Fire-scar formation in Jeffrey pine - mixed conifer forests in the Sierra San Pedro Martir, Mexico

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Scott L. Stephens; Danny L. Fry; Brandon M. Collins; Carl N. Skinner; Ernesto Franco-Vizcaino; Travis J. Freed

2010-01-01

Little is known about the probability of fire-scar formation. In this study, we examined all mixed conifer trees for fire-scar formation in a 16 ha watershed that burned as part of a 2003 wildfire in Sierra San Pedro Ma´rtir National Park (SSPM), Mexico. In addition, we examine the probability of fire-scar formation in relation to the previous fire interval in forests...

Seasonal photosynthetic activity in evergreen conifer leaves monitored with spectral reflectance

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Wong, C. Y.; Gamon, J. A.

2013-12-01

Boreal evergreen conifers must maintain photosynthetic systems in environments where temperatures vary greatly across seasons from high temperatures in the summer to freezing levels in the winter. This involves seasonal downregulation and photoprotection during periods of extreme temperatures. To better understand this downregulation, seasonal dynamics of photosynthesis of lodgepole (Pinus contorta D.) and ponderosa pine (Pinus ponderosa D.) were monitored in Edmonton, Canada over two years. Spectral reflectance at the leaf and stand scales was measured weekly and the Photochemical Reflectance Index (PRI), often used as a proxy for chlorophyll and carotenoid pigment levels and photosynthetic light-use efficiency (LUE), was used to track the seasonal dynamics of photosynthetic activity. Additional physiological measurements included leaf pigment content, chlorophyll fluorescence, and gas exchange. All the metrics indicate large seasonal changes in photosynthetic activity, with a sharp transition from winter downregulation to active photosynthesis in the spring and a more gradual fall transition into winter. The PRI was a good indicator of several other variables including seasonally changing photosynthetic activity, chlorophyll fluorescence, photosynthetic LUE, and pigment pool sizes. Over the two-year cycle, PRI was primarily driven by changes in constitutive (chlorophyll:carotenoid) pigment levels correlated with seasonal photosynthetic activity, with a much smaller variation caused by diurnal changes in xanthophyll cycle activity (conversion between violaxanthin & zeaxanthin). Leaf and canopy scale PRI measurements exhibited parallel responses during the winter-spring transition. Together, our findings indicate that evergreen conifers photosynthetic system possesses a remarkable degree of resilience in response to large temperature changes across seasons, and that optical remote sensing can be used to observe the seasonal effects on photosynthesis and

In situ fossil seedlings of a Metasequoia-like taxodiaceous conifer from Paleocene river floodplain deposits of central Alberta, Canada.

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Falder, A B; Stockey, R A; Rothwell, G W

1999-06-01

Fossil seeds and seedlings of a Metasequoia-like taxodiaceous conifer occur in Paleocene deposits at the Munce's Hill and Gao Mine localities of central Alberta, Canada. Compression/impression specimens are preserved in upright growth positions among seedlings of the cercidiphyllaceous dicot Joffrea speirsii Crane & Stockey. There are a large number of seeds, a few of which were buried while germinating and show a radicle or short primary root. More than 500 Metasequoia-like seedlings have been identified that have two linear cotyledons with parallel margins and rounded tips. Three specimens have been found that display three cotyledons. Slightly older seedlings show decussate pairs of leaves attached to the stem distal to the cotyledons. Still older seedlings have axillary branches that show varying sizes and numbers of opposite leaves arranged in a single plane distal to the opposite pairs. These specimens reveal that both Joffrea and this extinct taxodiaceous conifer were early colonizers of North American floodplain communities at the beginning of the Tertiary.

Predicting surface fuel models and fuel metrics using lidar and CIR imagery in a dense mixed conifer forest

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Marek K. Jakubowksi; Qinghua Guo; Brandon Collins; Scott Stephens; Maggi. Kelly

2013-01-01

We compared the ability of several classification and regression algorithms to predict forest stand structure metrics and standard surface fuel models. Our study area spans a dense, topographically complex Sierra Nevada mixed-conifer forest. We used clustering, regression trees, and support vector machine algorithms to analyze high density (average 9 pulses/m

Mixed-conifer forests of central Oregon: effects of logging and fire exclusion vary with environment.

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Merschel, Andrew G; Spies, Thomas A; Heyerdahl, Emily K

Twentieth-century land management has altered the structure and composition of mixed-conifer forests and decreased their resilience to fire, drought, and insects in many parts of the Interior West. These forests occur across a wide range of environmental settings and historical disturbance regimes, so their response to land management is likely to vary across landscapes and among ecoregions. However, this variation has not been well characterized and hampers the development of appropriate management and restoration plans. We identified mixed-conifer types in central Oregon based on historical structure and composition, and successional trajectories following recent changes in land use, and evaluated how these types were distributed across environmental gradients. We used field data from 171 sites sampled across a range of environmental settings in two subregions: the eastern Cascades and the Ochoco Mountains. We identified four forest types in the eastern Cascades and four analogous types with lower densities in the Ochoco Mountains. All types historically contained ponderosa pine, but differed in the historical and modern proportions of shade-tolerant vs. shade-intolerant tree species. The Persistent Ponderosa Pine and Recent Douglas-fir types occupied relatively hot–dry environments compared to Recent Grand Fir and Persistent Shade Tolerant sites, which occupied warm–moist and cold–wet environments, respectively. Twentieth-century selective harvesting halved the density of large trees, with some variation among forest types. In contrast, the density of small trees doubled or tripled early in the 20th century, probably due to land-use change and a relatively cool, wet climate. Contrary to the common perception that dry ponderosa pine forests are the most highly departed from historical conditions, we found a greater departure in the modern composition of small trees in warm–moist environments than in either hot–dry or cold–wet environments. Furthermore

Effects of thinning, residue mastication, and prescribed fire on soil and nutrient budgets in a Sierra Nevada mixed-conifer forest

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The effects of thinning followed by residue mastication (THIN), prescribed fire (BURN), and thinning plus residue mastication plus burning (T+B) on nutrient budgets and resin-based (plant root simulator [PRS] probe) measurements of soil nutrient availability in a mixed-conifer forest were measured. ...

Effects of thinning, residue mastication, and prescribed fire on soil and nutrient budgets in a Sierra Nevada mixed conifer forest

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The effects of thinning followed by residue mastication (THIN), prescribed fire (BURN), and thinning plus residue mastication plus burning (T+B) on nutrient budgets and resin-based (plant root simulator [PRS] probe) measurements of soil nutrient availability in a mixed-conifer forest were measured. ...

Contrasting Spatial Patterns in Active-Fire and Fire-Suppressed Mediterranean Climate Old-Growth Mixed Conifer Forests

OpenAIRE

Fry, Danny L.; Stephens, Scott L.; Collins, Brandon M.; North, Malcolm P.; Franco-Vizcaíno, Ernesto; Gill, Samantha J.

2014-01-01

In Mediterranean environments in western North America, historic fire regimes in frequent-fire conifer forests are highly variable both temporally and spatially. This complexity influenced forest structure and spatial patterns, but some of this diversity has been lost due to anthropogenic disruption of ecosystem processes, including fire. Information from reference forest sites can help management efforts to restore forests conditions that may be more resilient to future changes in disturbanc...

The poplar basic helix-loop-helix transcription factor BEE3 – Like gene affects biomass production by enhancing proliferation of xylem cells in poplar

Energy Technology Data Exchange (ETDEWEB)

Noh, Seol Ah, E-mail: s6022029@korea.ac.kr; Choi, Young-Im, E-mail: yichoi99@forest.go.kr; Cho, Jin-Seong, E-mail: jinsung3932@gmail.com; Lee, Hyoshin, E-mail: hslee@forest.go.kr

2015-06-19

Brassinosteroids (BRs) play important roles in many aspects of plant growth and development, including regulation of vascular cambium activities and cell elongation. BR-induced BEE3 (brassinosteroid enhanced expression 3) is required for a proper BR response. Here, we identified a poplar (Populus alba × Populus glandulosa) BEE3-like gene, PagBEE3L, encoding a putative basic helix-loop-helix (bHLH)-type transcription factor. Expression of PagBEE3L was induced by brassinolide (BL). Transcripts of PagBEE3L were mainly detected in stems, with the internode having a low level of transcription and the node having a relatively higher level. The function of the PagBEE3L gene was investigated through phenotypic analyses with PagBEE3L-overexpressing (ox) transgenic lines. This work particularly focused on a potential role of PagBEE3L in stem growth and development of polar. The PagBEE3L-ox poplar showed thicker and longer stems than wild-type plants. The xylem cells from the stems of PagBEE3L-ox plants revealed remarkably enhanced proliferation, resulting in an earlier thickening growth than wild-type plants. Therefore, this work suggests that xylem development of poplar is accelerated in PagBEE3L-ox plants and PagBEE3L plays a role in stem growth by increasing the proliferation of xylem cells to promote the initial thickening growth of poplar stems. - Highlights: • We identify the BEE3-like gene form hybrid poplar (Populus alba × Populus glandulosa). • We examine effects of overexpression of PagBEE3L on growth in poplar. • We found that 35S:BEE3L transgenic plants showed more rapid growth than wild-type plants. • BEE3L protein plays an important role in the development of plant stem.

The poplar basic helix-loop-helix transcription factor BEE3 – Like gene affects biomass production by enhancing proliferation of xylem cells in poplar

International Nuclear Information System (INIS)

Noh, Seol Ah; Choi, Young-Im; Cho, Jin-Seong; Lee, Hyoshin

2015-01-01

Brassinosteroids (BRs) play important roles in many aspects of plant growth and development, including regulation of vascular cambium activities and cell elongation. BR-induced BEE3 (brassinosteroid enhanced expression 3) is required for a proper BR response. Here, we identified a poplar (Populus alba × Populus glandulosa) BEE3-like gene, PagBEE3L, encoding a putative basic helix-loop-helix (bHLH)-type transcription factor. Expression of PagBEE3L was induced by brassinolide (BL). Transcripts of PagBEE3L were mainly detected in stems, with the internode having a low level of transcription and the node having a relatively higher level. The function of the PagBEE3L gene was investigated through phenotypic analyses with PagBEE3L-overexpressing (ox) transgenic lines. This work particularly focused on a potential role of PagBEE3L in stem growth and development of polar. The PagBEE3L-ox poplar showed thicker and longer stems than wild-type plants. The xylem cells from the stems of PagBEE3L-ox plants revealed remarkably enhanced proliferation, resulting in an earlier thickening growth than wild-type plants. Therefore, this work suggests that xylem development of poplar is accelerated in PagBEE3L-ox plants and PagBEE3L plays a role in stem growth by increasing the proliferation of xylem cells to promote the initial thickening growth of poplar stems. - Highlights: • We identify the BEE3-like gene form hybrid poplar (Populus alba × Populus glandulosa). • We examine effects of overexpression of PagBEE3L on growth in poplar. • We found that 35S:BEE3L transgenic plants showed more rapid growth than wild-type plants. • BEE3L protein plays an important role in the development of plant stem

Diversity and Seasonal Variation of Endophytic Fungi Isolated from Three Conifers in Mt. Taehwa, Korea

OpenAIRE

Kim, Chang-Kyun; Eo, Ju-Kyeong; Eom, Ahn-Heum

2013-01-01

The needled leaves of three conifer species were collected in Mt. Taehwa during different seasons of the year. Total 59 isolates and 19 species of endophytic fungi were isolated from the leaves and identified using morphological and molecular characteristics. As a result, Shannon index was different in its host plant; Larix kaempferi had a highest value of species diversity. According to the sampling season, 9 species of 19 species were isolated during fall season. The results suggest that th...

Short Communication. Comparing flammability traits among fire-stricken (low elevation and non fire-stricken (high elevation conifer forest species of Europe: A test of the Mutch hypothesis

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A. P. Dimitrakopoulos

2013-04-01

Full Text Available Aim of study. The flammability of the main coniferous forest species of Europe, divided into two groups according to their fire regime and altitudinal distribution, was tested in an effort to detect species-specific differences that may have an influence on community-wide fire regimes.Area of study. Conifer species comprising low- and high-elevation forests in Europe.Materials and Methods. The following conifer species were tested: low elevation; Pinus halepensis (Aleppo pine, Pinus brutia (Turkish pine, Pinus pinaster (maritime pine, Pinus pinea (stone pine and Cupressus sempervirens (cypress, high elevation (i.e., above 600 m a.s.l.; Pinus sylvestris (Scots pine, Abies alba (white fir, Picea excelsa (Norway spruce, Abies borissii regis (Macedonian fir and Pinus nigra (black pine. Flammability assessment (time-to-ignition and ignition temperature was conducted by an innovative ignition apparatus, heat content was measured with an IKA Adiabatic Bomb Calorimeter and ash content by heating 5 g of plant material in a muffle furnace at 650ºC for 1 h. Differences among species was statistically analysed by Duncan’s multiple comparison test.Main results. The results did not distinguish separate groups among traits between fire- and non-fire-stricken communities at the individual species level.Research highlights. Differences in fire regimes among low and high elevation conifer forests could be attributed either to differences in flammability of the plant communities as a whole (i.e., fuelbed or canopy properties vs. individual fuel properties or to other factors (climatic or anthropogenic.Key words: flammability; ignitability; heat content; ash content; conifer species; Mutch hypothesis.

Canopy arthropod responses to thinning and burning treatments in old-growth mixed-conifer forest in the Sierra Nevada, California

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Thomas Rambo; Timothy Schowalter; Malcolm North

2014-01-01

We compared canopy arthropod responses to common fuels reduction treatments at Teakettle Experimental Forest in the south-central Sierra Nevada of California. We sampled arthropod communities among four dominant overstory conifer species and three dominant understory angiosperm species before and after overstory or understory thinning or no thinning treatments followed...

Mapped DNA probes from Ioblolly pine can be used for restriction fragment length polymorphism mapping in other conifers

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M.R. Ahuja; M.E. Devey; A.T. Groover; K.D. Jermstad; D.B Neale

1994-01-01

A high-density genetic map based on restriction fragment length polymorphisms (RFLPs) is being constructed for loblolly pine (Pinus taeda L.). Consequently, a large number of DNA probes from loblolly pine are potentially available for use in other species. We have used some of these DNA probes to detect RFLPs in 12 conifers and an angiosperm....

Population isolation results in low genetic variation and high differentiation in Carolina hemlock (tsuga caroliniana), an imperiled southern Appalachian conifer

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Kevin M. Potter; Lia Campbell; Sedley A. Josserand; C. Dana Nelson; Robert M. Jetton

2017-01-01

Carolina hemlock (Tsuga caroliniana) is a rare conifer species that grows in small, isolated populations in the southern Appalachian Mountains of Virginia, North Carolina, South Carolina, Tennessee, and Georgia. The species is additionally imperiled by the hemlock woolly adelgid (Adelges tsugae), an invasive insect that can...

Structure and Composition of a Dry Mixed-Conifer Forest in Absence of Contemporary Treatments, Southwest, USA

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Douglas Cram

2017-09-01

Full Text Available Dry mixed-conifer forests in the Southwest occupy an important ecological and hydrological role in upper watersheds. In the absence of reoccurring fire and silvicultural treatments over the last 50 years, we quantified forest structure and composition on prevailing north and south aspects of a dry mixed-conifer forest in southcentral New Mexico using mixed models and ordination analysis in preparation for an experiment in ecological restoration. Results indicated overstory and midstory were dominated by Douglas-fir (Pseudotsuga menziesii and shade tolerant/fire intolerant white fir (Abies concolor with interspersed mature aspen on north aspects, and Douglas-fir and Southwestern white pine (Pinus strobiformis on south aspects. Ponderosa pine (Pinus ponderosa, which was historically co-dominant with Douglas-fir on north and south aspects, was subdominant on south aspects and almost entirely absent on north aspects. Regeneration was dominated by white fir saplings and seedlings on north aspects while ponderosa pine was completely absent. South aspect saplings and seedlings were characterized by Douglas-fir and Southwestern white pine, but almost no ponderosa pine. Ordination analysis characterized the effect of aspect on species composition. Understanding contemporary forest structure and composition is important when planning for desired future conditions that are to be achieved through ecological restoration using silvicultural techniques designed to foster resilience.

Stable Water Use Efficiency under Climate Change of Three Sympatric Conifer Species at the Alpine Treeline.

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Wieser, Gerhard; Oberhuber, Walter; Gruber, Andreas; Leo, Marco; Matyssek, Rainer; Grams, Thorsten Erhard Edgar

2016-01-01

The ability of treeline associated conifers in the Central Alps to cope with recent climate warming and increasing CO2 concentration is still poorly understood. We determined tree ring stable carbon and oxygen isotope ratios of Pinus cembra, Picea abies, and Larix decidua trees from 1975 to 2010. Stable isotope ratios were compared with leaf level gas exchange measurements carried out in situ between 1979 and 2007. Results indicate that tree ring derived intrinsic water-use efficiency (iWUE) of P. cembra, P. abies and L. decidua remained constant during the last 36 years despite climate warming and rising atmospheric CO2. Temporal patterns in Δ(13)C and Δ(18)O mirrored leaf level gas exchange assessments, suggesting parallel increases of CO2-fixation and stomatal conductance of treeline conifer species. As at the study site soil water availability was not a limiting factor iWUE remained largely stable throughout the study period. The stability in iWUE was accompanied by an increase in basal area increment (BAI) suggesting that treeline trees benefit from both recent climate warming and CO2 fertilization. Finally, our results suggest that iWUE may not change species composition at treeline in the Austrian Alps due to similar ecophysiological responses to climatic changes of the three sympatric study species.

Contribution to the study of the insect fauna of some conifer species in the region of Western Traras (Tlemcen - Algeria)

International Nuclear Information System (INIS)

Nichane, M.; Bouchikhi Tani, Z.; Khelil, M.A.

2013-01-01

Within the framework of the study of Biocenotic insects related to conifer species in Traras, the Western region of Tlemcen, a comprehensive knowledge of the insect fauna hosted by the Aleppo pine (Pinus halepensisMill.), Thuya Barbary (Tetraclinis articulata(Vahl) Masters)) and Cypress green(Cupressus sempervirensL) is essential. The various methods used for capturing insects allowed the collection of a large number of species, but a large number still remains unknown. These species are distributed among 10 orders of which the most important are the Coleoptera, Hymenoptera and Lepidoptera. Through this list of insects and the nature of their food, six diets to which these species belong were identified. The most representative are herbivores, auxiliaries and borers. This inventory allows the compilation of a list of insects harmful to the conifer species studied in this region. They total species including 9 phytophagous, 8 xylophagous, 7 seed-eating species, 5 opophages and one gall species. The auxiliaries are present with 26 species. (author)

Contrasting trait syndromes in angiosperms and conifers are associated with different responses of tree growth to temperature on a large scale

NARCIS (Netherlands)

Carnicer, Jofre; Brbeta, Adria; Sperlich, Dominik; Coll, Marta; Penuelas, Josep

2013-01-01

Recent large-scale studies of tree growth in the Iberian Peninsula reported contrasting positive and negative effects of temperature in Mediterranean angiosperms and conifers. Here we review the different hypotheses that may explain these trends and propose that the observed contrasting responses of

Scapoidus titanus performs a dual-meaning, sharpshooter-style EPG X wave in xylem and phloem: Could S. titanus be a potential vector of Xylella fastidiosa in European vineyards?

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In phytophagous hemipterans, salivary sheath-feeding species are described as xylem or phloem sap-ingesting specialists. Because these two food sources have different characteristics, two different feeding tactics are associated with this supposed specialization. Study of feeding behavior is crucial...

Effect of auxin on xylem tracheids differentiation in decapitated stems of Pinus silvestris L. and its interaction with some vitamins and growth regulators

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T. J. Wodzicki

2015-01-01

Full Text Available The effects of several vitamins and substances known as important agents in regulation of cell metabolism upon secondary xylem differentiation were studied in interaction with auxin (IAA as applied in lanoline to decapitated stems of 5-year-old Pinus silvestris trees in early and late-summer. Tested substances were: gibberellic acid, kinetin, nicotinic acid, thiamine, pyridoxine, calcium panthotenate, choline chloride, riboflavin, inositol, ascorbic acid, vitamin, A (alcohol, vitamin A (ester, saponin. None of the effects of these substances appeared significant enough to indicate the involvement in the seasonal variation of the response of cambium or differentiating tracheids to auxin. However, several effects, especially those of inositol, vitamin A and pyridoxine upon cambial xylem production and further stages of tracheid differentiation were observed. Auxin (IAA affected cambial activity and subsequent differentiation of tracheids during the earliest stages of cell ontogenesis. At these stages auxin treatment induced quantitative expression of the developmental processes involving radial growth and secondary wall formation by tracheids. In this respect, auxin did not affect cells advanced in differentiation, however, it proved to be an essential factor in the completion of the full cycle of tracheid ontogenesis.

Factors affecting distribution of wood, detritus, and sediment in headwater streams draining managed young-growth red alder - Conifer forests in southeast Alaska

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Gomi, T.; Johnson, A.C.; Deal, R.L.; Hennon, P.E.; Orlikowska, E.H.; Wipfli, M.S.

2006-01-01

Factors (riparian stand condition, management regimes, and channel properties) affecting distributions of wood, detritus (leaves and branches), and sediment were examined in headwater streams draining young-growth red alder (Alnus rubra Bong.) - conifer riparian forests (40 years old) remained in channels and provided sites for sediment and organic matter storage. Despite various alder-conifer mixtures and past harvesting effects, the abundance of large wood, fine wood, and detritus accumulations significantly decreased with increasing channel bank-full width (0.5-3.5 m) along relatively short channel distances (up to 700 m). Changes in wood, detritus, and sediment accumulations together with changes in riparian stand characteristics create spatial and temporal variability of in-channel conditions in headwater systems. A component of alder within young-growth riparian forests may benefit both wood production and biological recovery in disturbed headwater stream channels. ?? 2006 NRC.

Variations of Climate-Growth Response of Major Conifers at Upper Distributional Limits in Shika Snow Mountain, Northwestern Yunnan Plateau, China

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Yun Zhang

2017-10-01

Full Text Available Improved understanding of climate-growth relationships of multiple species is fundamental to understanding and predicting the response of forest growth to future climate change. Forests are mainly composed of conifers in Northwestern Yunnan Plateau, but variations of growth response to climate conditions among the species are not well understood. To detect the growth response of multiple species to climate change, we developed residual chronologies of four major conifers, i.e., George’s fir (Abies georgei Orr, Likiang spruce (Picea likiangensis (Franch. E.Pritz., Gaoshan pine (Pinus densata Mast. and Chinese larch (Larix potaninii Batalin at the upper distributional limits in Shika Snow Mountain. Using the dendroclimatology method, we analyzed correlations between the residual chronologies and climate variables. The results showed that conifer radial growth was influenced by both temperature and precipitation in Shika Snow Mountain. Previous November temperature, previous July temperature, and current May precipitation were the common climatic factors that had consistent influences on radial growth of the four species. Temperature in the previous post-growing season (September–October and moisture conditions in the current growing season (June–August were the common climatic factors that had divergent impacts on the radial growth of the four species. Based on the predictions of climate models and our understanding of the growth response of four species to climate variables, we may understand the growth response to climate change at the species level. It is difficult to predict future forest growth in the study area, since future climate change might cause both increases and decreases for the four species and indirect effects of climate change on forests should be considered.

Regulation of Water Use in the Southernmost European Fir (Abies pinsapo Boiss.: Drought Avoidance Matters

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Raúl Sánchez-Salguero

2015-06-01

Full Text Available The current scenario of global warming has resulted in considerable uncertainty regarding the capacity of forest trees to adapt to increasing drought. Detailed ecophysiological knowledge would provide a basis to forecast expected species dynamics in response to climate change. Here, we compare the water balance (stomatal conductance, xylem water potential, needle osmotic adjustment of Abies pinsapo, a relict drought-sensitive Mediterranean fir, along an altitudinal gradient. We related these variables to soil water and nutrient availability, air temperature, atmospheric water potential, and vapour pressure deficit during two consecutive years. Our results indicate that A. pinsapo closed stomata rapidly over a very narrow range of soil water availability and atmospheric dryness. This isohydric response during water stress suggests that this relict conifer relied on the plant hormone abscisic acid to maintain closed stomata during sustained drought, instead of needle desiccation to passively drive stomatal closure, needle osmotic adjustment or a plastic response of the xylem to different levels of water availability. Both the soil and foliar nutrient contents suggest that the studied populations are not limited by nutrient deficiencies, and drought was stronger in the warmer low-elevation areas.

Anisohydric water use behavior links growing season evaporative demand to ring-width increment in conifers from summer-dry environments

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Steve L. Voelker; R. Justin DeRose; Matthew F. Bekker; Chalita Sriladda; Nisa Leksungnoen; Roger K. Kjelgren

2018-01-01

Conifers in the Pinaceae and Cupressaceae from dry environments have been shown to broadly differ in their stomatal sensitivity to soil drying that result in isohydric versus anisohydric water use behavior, respectively. Here, we first employ a series of drought experiments and field observations to confirm the degree of isohydric versus anisohydric water use behavior...

Extraction and estimation of the quantity of calcium oxalate crystals in the foliage of conifer and hardwood trees

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Rakesh Minocha; Bradley Chamberlain; Stephanie Long; Swathi A. Turlapati; Gloria. Quigley

2015-01-01

The main goal of this study was to develop a method for the extraction and indirect estimation of the quantity of calcium oxalate (CaOx) in the foliage of trees. Foliar tissue was collected from a single tree of each species (five conifers and five hardwoods) for comparison of extractions in different solvents using 10 replicates per species from the same pool of...

Divergence in strategies for coping with winter embolism among co-occurring temperate tree species: the role of positive xylem pressure, wood type and tree stature

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Cun-Yang Niu; Frederick C. Meinzer; Guang-You. Hao

2017-01-01

1. In temperate ecosystems, freeze-thaw events are an important environmental stress that can induce severe xylem embolism (i.e. clogging of conduits by air bubbles) in overwintering organs of trees. However, no comparative studies of different adaptive strategies among sympatric tree species for coping with winter embolism have examined the potential role of the...

Connecting long term species changes and their water competitions in temperate forest Mt. Baegun, Rep. of Korea using hydrogen and oxygen stable isotope analysis

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Jeon, J.; Lee, H.; Lee, M.; Song, W.; Byeon, S.; Lee, B.; Cho, S.; Park, J.; Kim, H. S.

2017-12-01

Many dynamic vegetation model simulations have predicted dramatic changes in species composition of temperate forests due to climate changes and successional reasons. Especially, conifer species are expected to lose their habitats and to be replaced by broadleaf species. Similarly, our more than 15-years-long 880 permenant plots tree survey data in Mt. Baegun, Rep. of Korea, showed substantial decrease of conifer species and their productivities and increase of broadleaved species. One of main reasons for these changes in species could be attributed to the water competition among tree species in the same stand. Therefore, we investigated the differences in water uptake scheme between conifer and broadleaf species from the temperate forests of Korea using stable isotopes. Six study plots showing high competition (conifers vs. broadleaf species) based on previous vegetation survey were chosen and the species-specific water uptake depth was estimated by measuring hydrogen(δ2H) and oxygen(δ18O) ratio from the xylem sap and leaves of individual species and by comparing them with those of soil water from 5 depths, (10, 30, 50, 100 and 120 cm), which extracted by lysimeter. The collection was conducted from April 2016 to Nov 2017. The conifer species included Pinus densiflora and Chamaecyparis obtusa vs. broadleaved species included Carpinus laxiflora, Prunus sargentii, Styrax obassia, Lindera erythrocarpa and Quercus species such as Q. mongolica, Q. serrata, Q. accuticima. Preliminary results showed the stable isotope signatures of soil water was increased from 10 cm to 30 cm, and then decreased gradually until 120 cm. In addition, current dominant canopy species, Chamaecyparis obtusa absorbed majority of their water from 10 to 30 cm depth. In comparison, current mid canopy but one of upcoming dominant species, Styrax obassia's major water source was 30 cm and deeper of soil. Our results could be essential for the prediction of species composition under climate change

Changes of plant hormone levels in conifers subjected to immissions. Hormongehaltsaenderungen in Nadelbaeumen unter Immissionsbelastung

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Frenzel, B.; Christmann, A. (Hohenheim Univ., Stuttgart (Germany, F.R.). Inst. fuer Botanik)

1989-04-01

The effect of reduced immissions on the phytohormone balance in conifers (ethylene, abscisic acid) is investigated on two sites: 1. The first site was under strong SO{sub 2}-impact until autumn 1987. 2. On the second site, spruce trees in open top chambers receiving charcoal-filtered air are compared with trees outside the chambers and trees in chambers receiving ambient air. Until now there are no systematic and significant differences seen in the hormone contents of the differently treated groups of trees. (orig./KG).

Impacts of long-term precipitation manipulation on hydraulic architecture and xylem anatomy of piñon and juniper in Southwest USA.

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Hudson, P J; Limousin, J M; Krofcheck, D J; Boutz, A L; Pangle, R E; Gehres, N; McDowell, N G; Pockman, W T

2018-02-01

Hydraulic architecture imposes a fundamental control on water transport, underpinning plant productivity, and survival. The extent to which hydraulic architecture of mature trees acclimates to chronic drought is poorly understood, limiting accuracy in predictions of forest responses to future droughts. We measured seasonal shoot hydraulic performance for multiple years to assess xylem acclimation in mature piñon (Pinus edulis) and juniper (Juniperus monosperma) after 3+ years of precipitation manipulation. Our treatments consisted of water addition (+20% ambient precipitation), partial precipitation-exclusion (-45% ambient precipitation), and exclusion-structure control. Supplemental watering elevated leaf water potential, sapwood-area specific hydraulic conductivity, and leaf-area specific hydraulic conductivity relative to precipitation exclusion. Shifts in allocation of leaf area to sapwood area enhanced differences between irrigated and droughted K L in piñon but not juniper. Piñon and juniper achieved similar K L under ambient conditions, but juniper matched or outperformed piñon in all physiological measurements under both increased and decreased precipitation treatments. Embolism vulnerability and xylem anatomy were unaffected by treatments in either species. Absence of significant acclimation combined with inferior performance for both hydraulic transport and safety suggests piñon has greater risk of local extirpation if aridity increases as predicted in the southwestern USA. © 2017 John Wiley & Sons Ltd.

Drought responses of conifers in ecotone forests of northern Arizona: tree ring growth and leaf delta13C.

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Adams, Henry D; Kolb, Thomas E

2004-07-01

We sought to understand differences in tree response to meteorological drought among species and soil types at two ecotone forests in northern Arizona, the pinyon-juniper woodland/ponderosa pine ecotone, and the higher elevation, wetter, ponderosa pine/mixed conifer ecotone. We used two approaches that provide different information about drought response: the ratio of standardized radial growth in wet years to dry years (W:D) for the period between years 1950 and 2000 as a measure of growth response to drought, and delta13C in leaves formed in non-drought (2001) and drought (2002) years as a measure of change in water use efficiency (WUE) in response to drought. W:D and leaf delta13C response to drought for Pinus edulis and P. ponderosa did not differ for trees growing on coarse-texture soils derived from cinders compared with finer textured soils derived from flow basalts or sedimentary rocks. P. ponderosa growing near its low elevation range limit at the pinyon-juniper woodland/ponderosa pine ecotone had a greater growth response to drought (higher W:D) and a larger increase in WUE in response to drought than co-occurring P. edulis growing near its high elevation range limit. P. flexilis and Pseudotsuga menziesii growing near their low elevation range limit at the ponderosa pine/mixed conifer ecotone had a larger growth response to drought than co-occurring P. ponderosa growing near its high elevation range limit. Increases in WUE in response to drought were similar for all species at the ponderosa pine/mixed conifer ecotone. Low elevation populations of P. ponderosa had greater growth response to drought than high-elevation populations, whereas populations had a similar increase in WUE in response to drought. Our findings of different responses to drought among co-occurring tree species and between low- and high-elevation populations are interpreted in the context of drought impacts on montane coniferous forests of the southwestern USA.

Stable water use efficiency under climate change of three sympatric conifer species at the Alpine treeline

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Gerhard eWieser

2016-06-01

Full Text Available The ability of treeline associated conifers in the Central Alps to cope with recent climate warming and increasing CO2 concentration is still poorly understood. We determined tree ring stable carbon and oxygen isotope ratios of Pinus cembra, Picea abies and Larix decidua trees from 1975-2010. Stable isotope ratios were compared with leaf level gas exchange measurements carried out in situ between 1979 and 2007. Results indicate that tree ring derived intrinsic water-use efficiency (iWUE of P. cembra, P. abies and L. decidua remained constant during the last 36 years despite climate warming and rising atmospheric CO2. Temporal patterns in Δ13C and Δ18O mirrored leaf level gas exchange assessments, suggesting parallel increases of CO2-fixation and stomatal conductance of treeline conifer species. As at the study site soil water availability was not a limiting factor iWUE remained largely stable throughout the study period. The stability in iWUE was accompanied by an increase in basal area increment (BAI suggesting that treeline trees benefit from both recent climate warming and CO2 fertilization. Finally, our results suggest that iWUE may not change species composition at treeline in the Austrian Alps due to similar ecophysiological responses to climatic changes of the three sympatric study species.

Remotely sensed predictors of conifer tree mortality during severe drought

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Brodrick, P. G.; Asner, G. P.

2017-11-01

Widespread, drought-induced forest mortality has been documented on every forested continent over the last two decades, yet early pre-mortality indicators of tree death remain poorly understood. Remotely sensed physiological-based measures offer a means for large-scale analysis to understand and predict drought-induced mortality. Here, we use laser-guided imaging spectroscopy from multiple years of aerial surveys to assess the impact of sustained canopy water loss on tree mortality. We analyze both gross canopy mortality in 2016 and the change in mortality between 2015 and 2016 in millions of sampled conifer forest locations throughout the Sierra Nevada mountains in California. On average, sustained water loss and gross mortality are strongly related, and year-to-year water loss within the drought indicates subsequent mortality. Both relationships are consistent after controlling for location and tree community composition, suggesting that these metrics may serve as indicators of mortality during a drought.

Evolution of conifer diterpene synthases: diterpene resin acid biosynthesis in lodgepole pine and jack pine involves monofunctional and bifunctional diterpene synthases.

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Hall, Dawn E; Zerbe, Philipp; Jancsik, Sharon; Quesada, Alfonso Lara; Dullat, Harpreet; Madilao, Lina L; Yuen, Macaire; Bohlmann, Jörg

2013-02-01

Diterpene resin acids (DRAs) are major components of pine (Pinus spp.) oleoresin. They play critical roles in conifer defense against insects and pathogens and as a renewable resource for industrial bioproducts. The core structures of DRAs are formed in secondary (i.e. specialized) metabolism via cycloisomerization of geranylgeranyl diphosphate (GGPP) by diterpene synthases (diTPSs). Previously described gymnosperm diTPSs of DRA biosynthesis are bifunctional enzymes that catalyze the initial bicyclization of GGPP followed by rearrangement of a (+)-copalyl diphosphate intermediate at two discrete class II and class I active sites. In contrast, similar diterpenes of gibberellin primary (i.e. general) metabolism are produced by the consecutive activity of two monofunctional class II and class I diTPSs. Using high-throughput transcriptome sequencing, we discovered 11 diTPS from jack pine (Pinus banksiana) and lodgepole pine (Pinus contorta). Three of these were orthologous to known conifer bifunctional levopimaradiene/abietadiene synthases. Surprisingly, two sets of orthologous PbdiTPSs and PcdiTPSs were monofunctional class I enzymes that lacked functional class II active sites and converted (+)-copalyl diphosphate, but not GGPP, into isopimaradiene and pimaradiene as major products. Diterpene profiles and transcriptome sequences of lodgepole pine and jack pine are consistent with roles for these diTPSs in DRA biosynthesis. The monofunctional class I diTPSs of DRA biosynthesis form a new clade within the gymnosperm-specific TPS-d3 subfamily that evolved from bifunctional diTPS rather than monofunctional enzymes (TPS-c and TPS-e) of gibberellin metabolism. Homology modeling suggested alterations in the class I active site that may have contributed to their functional specialization relative to other conifer diTPSs.

Diversity and seasonal variation of endophytic fungi isolated from three conifers in mt. Taehwa, Korea.

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Kim, Chang-Kyun; Eo, Ju-Kyeong; Eom, Ahn-Heum

2013-06-01

The needled leaves of three conifer species were collected in Mt. Taehwa during different seasons of the year. Total 59 isolates and 19 species of endophytic fungi were isolated from the leaves and identified using morphological and molecular characteristics. As a result, Shannon index was different in its host plant; Larix kaempferi had a highest value of species diversity. According to the sampling season, 9 species of 19 species were isolated during fall season. The results suggest that the existing of host plant and sampling season are major factors of distribution of endophytic fungi.

Fire performance in traditional silvicultural and fire and fire surrogate treatments in Sierran mixed-conifer forests: a brief summary

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Jason J. Moghaddas; Scott L. Stephens

2007-01-01

Mixed conifer forests cover 7.9 million acres of California’s total land base. Forest structure in these forests has been influenced by harvest practices and silvicultural systems implemented since the beginning of the California Gold Rush in 1849. Today, the role of fire in coniferous forests, both in shaping past stand structure and its ability to shape future...

Intra-Annual Xylem Growth of Larix principis-rupprechtii at Its Upper and Lower Distribution Limits on the Luyashan Mountain in North-Central China

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Yuan Jiang

2015-10-01

Full Text Available Altitude-related climatic factors, especially temperature, are important factors that affect tree growth in mountain forest ecosystems. The aims of this study were to estimate the intra-annual radial growth differences of Larix principis-rupprechtii (L. principis-rupprechtii between its upper and lower distribution limits, at 2740 and 2040 m a.s.l, respectively. Dynamics of xylem growth were observed by collecting microcore samples weekly during the 2011 growth season. The result indicated that different strategies were adopted at the two selected sites. Trees at the upper distribution limit adopted an “intensive strategy” with higher maximum growth rates (0.69 cell·day−1 within a shorter duration of 95 days, producing 21 new tracheids. By contrast, trees at the lower distribution limit exhibited an “extensive strategy” with lower maximum growth rates (0.53 cell·day−1 over a longer duration of 135 days, producing 50 tracheids. The soil temperature was probably the main factor limiting the onset of cambial activity for L. principis-rupprechtii, its daily mean thresholds for onset were 0 °C and 1.4 °C at the upper and lower distribution limits, respectively. These results indicate that L. principis-rupprechtii is able to adjust its xylem growth according to environmental conditions.

Investigating water transport through the xylem network in vascular plants.

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Kim, Hae Koo; Park, Joonghyuk; Hwang, Ildoo

2014-04-01

Our understanding of physical and physiological mechanisms depends on the development of advanced technologies and tools to prove or re-evaluate established theories, and test new hypotheses. Water flow in land plants is a fascinating phenomenon, a vital component of the water cycle, and essential for life on Earth. The cohesion-tension theory (CTT), formulated more than a century ago and based on the physical properties of water, laid the foundation for our understanding of water transport in vascular plants. Numerous experimental tools have since been developed to evaluate various aspects of the CTT, such as the existence of negative hydrostatic pressure. This review focuses on the evolution of the experimental methods used to study water transport in plants, and summarizes the different ways to investigate the diversity of the xylem network structure and sap flow dynamics in various species. As water transport is documented at different scales, from the level of single conduits to entire plants, it is critical that new results be subjected to systematic cross-validation and that findings based on different organs be integrated at the whole-plant level. We also discuss the functional trade-offs between optimizing hydraulic efficiency and maintaining the safety of the entire transport system. Furthermore, we evaluate future directions in sap flow research and highlight the importance of integrating the combined effects of various levels of hydraulic regulation.

Towards improved quantification of post-fire conifer mortality and recovery: Impacts of fire radiative flux on seedling and mature tree mortality, physiology, and growth

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Sparks, A. M.; Kolden, C.; Smith, A. M.

2016-12-01

Fire activity, in terms of intensity, frequency, and total area burned, is expected to increase with changing climate. A challenge for landscape level assessment of fire effects, termed burn severity, is that current assessments provide very little information regarding vegetation physiological performance and recovery, limiting our understanding of fire effects on ecosystem services such as carbon storage/cycling. To address these limitations, we evaluated an alternative dose-response methodology for quantifying fire effects that attempts to bridge fire combustion dynamics and ecophysiology. Specifically, we conducted a highly controlled, laboratory assessment of seedling response to increasing doses of fire radiative energy applied through surface fires, for two western U.S. conifer species. Seedling physiology and spectral reflectance were acquired pre- and up to 1 year post-fire. Post-fire mortality, physiological performance, and spectral reflectance were strongly related with fire radiative energy density (FRED: J m-2) dose. To examine how these relationships change with tree size and age, we conducted small prescribed fires at the tree scale (35 m2) in a mature conifer stand. Radial growth and resin duct defenses were assessed on the mature conifer trees following the prescribed fires. Differences in dose-response relationships between seedlings and mature trees indicate the importance of fire behavior (e.g., flaming-dominated versus smoldering-dominated combustion) in characterizing these relationships. Ultimately, these results suggest that post-fire impacts on growth of surviving seedlings and mature trees require modes of heat transfer to impact tree canopies.

Quantifying the impact of daily and seasonal variation in sap pH on xylem dissolved inorganic carbon estimates in plum trees.

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Erda, F G; Bloemen, J; Steppe, K

2014-01-01

In studies on internal CO2 transport, average xylem sap pH (pH(x)) is one of the factors used for calculation of the concentration of dissolved inorganic carbon in the xylem sap ([CO2 *]). Lack of detailed pH(x) measurements at high temporal resolution could be a potential source of error when evaluating [CO2*] dynamics. In this experiment, we performed continuous measurements of CO2 concentration ([CO2]) and stem temperature (T(stem)), complemented with pH(x) measurements at 30-min intervals during the day at various stages of the growing season (Day of the Year (DOY): 86 (late winter), 128 (mid-spring) and 155 (early summer)) on a plum tree (Prunus domestica L. cv. Reine Claude d'Oullins). We used the recorded pH(x) to calculate [CO2*] based on T(stem) and the corresponding measured [CO2]. No statistically significant difference was found between mean [CO2*] calculated with instantaneous pH(x) and daily average pH(x). However, using an average pH(x) value from a different part of the growing season than the measurements of [CO2] and T(stem) to estimate [CO2*] led to a statistically significant error. The error varied between 3.25 ± 0.01% under-estimation and 3.97 ± 0.01% over-estimation, relative to the true [CO2*] data. Measured pH(x) did not show a significant daily variation, unlike [CO2], which increased during the day and declined at night. As the growing season progressed, daily average [CO2] (3.4%, 5.3%, 7.4%) increased and average pH(x) (5.43, 5.29, 5.20) decreased. Increase in [CO2] will increase its solubility in xylem sap according to Henry's law, and the dissociation of [CO2*] will negatively affect pH(x). Our results are the first quantifying the error in [CO2*] due to the interaction between [CO2] and pH(x) on a seasonal time scale. We found significant changes in pH(x) across the growing season, but overall the effect on the calculation of [CO2*] remained within an error range of 4%. However, it is possible that the error could be more

Process for preparing conifers, particularly conifers with little wood content to obtain energy sources and raw materials. Verfahren zur Aufbereitung von Koniferen, insbesondere holzarmer Koniferen zur Gewinnung von Energietraegern und Rohstoffen

Energy Technology Data Exchange (ETDEWEB)

Fischer, K.O.P.

1981-11-26

The object of the invention is a process for preparing root stocks, roots, bark and branches and twigs carrying needles or scales and seed capsules of conifers, where fuel and raw materials for hydrotherapy are obtained. The material used is reduced in size by beating and rubbing in pulverisers to a coarse grained mixture, which is reduced in size in further grinding processes in a mill to a mean grain size of 0.5 to 1 mm. The material dried during grinding by waste heat can be used directly as a powdery or fine-grained fuel, made into briquettes or non-wearing shapes or can be taken to a hydrocarbon conversion process or made into a bath extract.

THE DEVELOPMENT OF THE SECONDARY WALL OF THE XYLEM IN ACER PSEUDOPLATANUS

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Wooding, F. B. P.; Northcote, D. H.

1964-01-01

The development of the spirally thickened xylem element from a cambium initial of sycamore Acer pseudoplatanus has been traced by means of electron microscopy. The narrow elongated cambial initial undergoes considerable expansion in all dimensions. The cytoplasm at this stage is distributed in a thin skin between the cell wall and a large vacuole. No correlation has been observed between the distribution of any organelle and the pattern of the eventual thickenings. After the sites of thickening deposition have become apparent, the most conspicuous feature of the cell is the proliferation of Golgi bodies and vesicles. It is suggested that the material of the developing thickenings stems from direct apposition of the material in the Golgi vesicles. After glutaraldehyde fixation, microtubules (200 to 220 A in diameter) are seen to be sited in specific relation to the thickenings, the orientation of the tubules mirroring that of the fibrils seen in the thickenings. Possible reasons for absence of an observable pattern in the expanded but relatively undifferentiated cell are given, and the possible roles of the Golgi apparatus and microtubules in the thickening production are discussed PMID:14222817

Spatial variation of vessel grouping in the xylem of Betula platyphylla Roth.

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Zhao, Xiping

2016-01-01

Vessel grouping in angiosperms may improve hydraulic integration and increase the spread of cavitations through redundancy pathways. Although disputed, it is increasingly attracting research interest as a potentially significant hydraulic trait. However, the variation of vessel grouping in a tree is poorly understood. I measured the number of solitary and grouped vessels in the xylem of Betula platyphylla Roth. from the pith to the bark along the water flow path. The vessel grouping parameters included the mean number of vessels per vessel group (VG), percentage of solitary vessels (SVP), percentage of radial multiple vessels (MVP), and percentage of cluster vessels (CVP). The effects of cambial age (CA) and flow path-length (PL) on the vessel grouping were analyzed using a linear mixed model.VG and CVP increased nonlinearly, SVP decreased nonlinearly with PL. In trunks and branches, VG and CVP decreased nonlinearly, and SVP increased nonlinearly with CA. In roots, the parameters had no change with CA. MVP was almost constant with PL or CA. The results suggest that vessel grouping has a nonrandom variation pattern, which is affected deeply by cambial age and water flow path.

Contrasting spatial patterns in active-fire and fire-suppressed Mediterranean climate old-growth mixed conifer forests.

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Fry, Danny L; Stephens, Scott L; Collins, Brandon M; North, Malcolm P; Franco-Vizcaíno, Ernesto; Gill, Samantha J

2014-01-01

In Mediterranean environments in western North America, historic fire regimes in frequent-fire conifer forests are highly variable both temporally and spatially. This complexity influenced forest structure and spatial patterns, but some of this diversity has been lost due to anthropogenic disruption of ecosystem processes, including fire. Information from reference forest sites can help management efforts to restore forests conditions that may be more resilient to future changes in disturbance regimes and climate. In this study, we characterize tree spatial patterns using four-ha stem maps from four old-growth, Jeffrey pine-mixed conifer forests, two with active-fire regimes in northwestern Mexico and two that experienced fire exclusion in the southern Sierra Nevada. Most of the trees were in patches, averaging six to 11 trees per patch at 0.007 to 0.014 ha(-1), and occupied 27-46% of the study areas. Average canopy gap sizes (0.04 ha) covering 11-20% of the area were not significantly different among sites. The putative main effects of fire exclusion were higher densities of single trees in smaller size classes, larger proportion of trees (≥ 56%) in large patches (≥ 10 trees), and decreases in spatial complexity. While a homogenization of forest structure has been a typical result from fire exclusion, some similarities in patch, single tree, and gap attributes were maintained at these sites. These within-stand descriptions provide spatially relevant benchmarks from which to manage for structural heterogeneity in frequent-fire forest types.

A 6-year-long manipulation with soil warming and canopy nitrogen additions does not affect xylem phenology and cell production of mature black spruce

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Madjelia Cangre Ebou eDAO

2015-11-01

Full Text Available The predicted climate warming and increased atmospheric inorganic nitrogen deposition are expected to have dramatic impacts on plant growth. However, the extent of these effects and their interactions remains unclear for boreal forest trees. The aim of this experiment was to investigate the effects of increased soil temperature and nitrogen (N depositions on stem intra-annual growth of two mature stands of black spruce [Picea mariana (Mill. BSP] in Quebec, Canada. During 2008-2013, the soil around mature trees was warmed up by 4 °C with heating cables during the growing season and precipitations containing three times the current inorganic N concentration were added by frequent canopy applications. Xylem phenology and cell production were monitored weekly from April to October. The 6-year-long experiment performed in two sites at different altitude showed no substantial effect of warming and N-depositions on xylem phenological phases of cell enlargement, wall thickening and lignification. Cell production, in terms of number of tracheids along the radius, also did not differ significantly and followed the same patterns in control and treated trees. These findings allowed the hypothesis of a medium-term effect of soil warming and N depositions on the growth of mature black spruce to be rejected.

Regeneration in United States Department of Agriculture Forest Service mixed conifer partial cuttings in the Blue Mountains of Oregon and Washington.

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K.W. Seidel; S. Conrade. Head

1983-01-01

A survey in the Blue Mountains of north-eastern Oregon and southeastern Washington showed that, on the average, partial cuts in the grand fir/big huckleberry community were well stocked with a mixture of advance, natural post-harvest, and planted reproduction of a number of species. Partial cuts in the mixed conifer/pinegrass community had considerably fewer seedlings...

The annealing temperature dependences of microstructures and magnetic properties in electro-chemical deposited CoNiFe thin films

International Nuclear Information System (INIS)

Suharyadi, Edi; Riyanto, Agus; Abraha, Kamsul

2016-01-01

CoNiFe thin films with various compositions had been successfully fabricated using electro-chemical deposition method. The crystal structure of Co_6_5Ni_1_5Fe_2_0, Co_6_2Ni_1_5Fe_2_3, and Co_5_5Ni_1_5Fe_3_0 thin films was fcc, bcc-fcc mix, and bcc, respectively. The difference crystal structure results the difference in magnetic properties. The saturation magnetic flux density (Bs) of Co_6_5Ni_1_5Fe_2_0, Co_6_2Ni_1_5Fe_2_3, and Co_5_5Ni_1_5Fe_3_0 thin films was 1.89 T, 1.93 T, and 2.05 T, respectively. An optimal annealing temperature was determined for controlling the microstructure and magnetic properties of CoNiFe thin films. Depending on annealing temperature, the ratio of bcc and fcc structure varied without changing the film composition. By annealing at temperature of T ≥ 350°C, the intensity ratio of X-ray diffraction peaks for bcc(110) to fcc(111) increased. The increase of phase ratio of bcc(110) to fcc(111) caused the increase of Bs, from 1.89 T to 1.95 T. Coercivity (Hc) also increased after annealing, from 2.6 Oe to 18.6 Oe for fcc phase thin films, from 2.0 Oe to 12.0 Oe for fcc-bcc mix phase thin films, and 7.8 Oe to 8 Oe for bcc phase thin films. The changing crystal structures during annealing process indicated that the thermal treatment at high temperature cause the changing crystallinity and atomic displacement. The TEM bright-field images with corresponding selected-area electron diffraction (SAED) patterns showed that there are strongly effects of thermal annealing on the size of fcc and bcc phase crystalline grain as described by size of individual spot and discontinuous rings. The size of crystalline grains increased by thermal annealing. The evolution of bcc and fcc structures of CoNiFe during annealing is though to be responsible for the change of magnetic properties.

The conversion of evenaged into unevenaged mixed conifer forests in southern British Columbia

Energy Technology Data Exchange (ETDEWEB)

Eichel, G.H.

1995-12-31

A detailed description of the conditions and history leading to the establishment and continuity of all-aged mixed coniferous forests in the montane south central region of British Columbia, Canada. Also described are the attempts by one forest products company to perpetuate and proportionally increase this type of forest cover through the selective removal necessitated by bark beetle depredation of the component, Pinus contorta. The report concludes with a description of and recommendations for the post-harvest management employing treatments which imitate natural conditions leading to a gradual and lasting conversion of natural multi-species stands into unevenaged or all-aged stands of mixed conifers which are conducive to single tree or group selection harvests at more or less regular intervals. 10 figs, 1 tab

The conversion of evenaged into unevenaged mixed conifer forests in southern British Columbia

Energy Technology Data Exchange (ETDEWEB)

Eichel, G H

1996-12-31

A detailed description of the conditions and history leading to the establishment and continuity of all-aged mixed coniferous forests in the montane south central region of British Columbia, Canada. Also described are the attempts by one forest products company to perpetuate and proportionally increase this type of forest cover through the selective removal necessitated by bark beetle depredation of the component, Pinus contorta. The report concludes with a description of and recommendations for the post-harvest management employing treatments which imitate natural conditions leading to a gradual and lasting conversion of natural multi-species stands into unevenaged or all-aged stands of mixed conifers which are conducive to single tree or group selection harvests at more or less regular intervals. 10 figs, 1 tab

Contrasting nutritional acclimation of sugar maple (Acer saccharum Marsh. and red maple (Acer rubrum L. to increasing conifers and soil acidity as demonstrated by foliar nutrient balances

Directory of Open Access Journals (Sweden)

Alexandre Collin

2016-07-01

Full Text Available Sugar maple (Acer saccharum Marshall, SM is believed to be more sensitive to acidic and nutrient-poor soils associated with conifer-dominated stands than red maple (Acer rubrum L., RM. Greater foliar nutrient use efficiency (FNUE of RM is likely the cause for this difference. In the context of climate change, this greater FNUE could be key in favouring northward migration of RM over SM. We used the concept of foliar nutrient balances to study the nutrition of SM and RM seedlings along an increasing gradient in forest floor acidity conditioned by increasing proportions of conifers (pH values ranging from 4.39 under hardwoods, to 4.29 under mixed hardwood-conifer stands and 4.05 under conifer-dominated stands. Nutrients were subjected to isometric log-ratio (ilr transformation, which views the leaf as one closed system and considers interactions between nutrients. The ilr method eliminates numerical biases and weak statistical inferences based on raw or operationally’’ log-transformed data. We analyzed foliar nutrients of SM and RM seedlings and found that the [Ca,Mg,K|P,N] and [Ca,Mg|K] balances of SM seedlings were significantly different among soil acidity levels, whereas they did not vary for RM seedlings. For SM seedlings, these differences among soil acidity levels were due to a significant decrease in foliar Ca and Mg concentrations with increasing forest floor acidity. Similar differences in foliar balances were also found between healthy and declining SM stands estimated from literature values. Conversely, foliar balances of RM seedlings did not differ among soil acidity levels, even though untransformed foliar nutrient concentrations were significantly different. This result highlights the importance of using ilr transformation, since it provides more sensitive results than standard testing of untransformed nutrient concentrations. The lower nutrient requirements of RM and its greater capacity to maintain nutrient equilibrium are

Two phloem nitrate transporters, NRT1.11 and NRT1.12, are important for redistributing xylem-borne nitrate to enhance plant growth.

Science.gov (United States)

Hsu, Po-Kai; Tsay, Yi-Fang

2013-10-01

This study of the Arabidopsis (Arabidopsis thaliana) nitrate transporters NRT1.11 and NRT1.12 reveals how the interplay between xylem and phloem transport of nitrate ensures optimal nitrate distribution in leaves for plant growth. Functional analysis in Xenopus laevis oocytes showed that both NRT1.11 and NRT1.12 are low-affinity nitrate transporters. Quantitative reverse transcription-polymerase chain reaction and immunoblot analysis showed higher expression of these two genes in larger expanded leaves. Green fluorescent protein and β-glucuronidase reporter analyses indicated that NRT1.11 and NRT1.12 are plasma membrane transporters expressed in the companion cells of the major vein. In nrt1.11 nrt1.12 double mutants, more root-fed (15)NO3(-) was translocated to mature and larger expanded leaves but less to the youngest tissues, suggesting that NRT1.11 and NRT1.12 are required for transferring root-derived nitrate into phloem in the major veins of mature and larger expanded leaves for redistributing to the youngest tissues. Distinct from the wild type, nrt1.11 nrt1.12 double mutants show no increase of plant growth at high nitrate supply. These data suggested that NRT1.11 and NRT1.12 are involved in xylem-to-phloem transfer for redistributing nitrate into developing leaves, and such nitrate redistribution is a critical step for optimal plant growth enhanced by increasing external nitrate.

Metabolite profiling reveals a role for atypical cinnamyl alcohol dehydrogenase CAD1 in the synthesis of coniferyl alcohol in tobacco xylem.

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Damiani, Isabelle; Morreel, Kris; Danoun, Saïda; Goeminne, Geert; Yahiaoui, Nabila; Marque, Christiane; Kopka, Joachim; Messens, Eric; Goffner, Deborah; Boerjan, Wout; Boudet, Alain-Michel; Rochange, Soizic

2005-11-01

In angiosperms, lignin is built from two main monomers, coniferyl and sinapyl alcohol, which are incorporated respectively as G and S units in the polymer. The last step of their synthesis has so far been considered to be performed by a family of dimeric cinnamyl alcohol dehydrogenases (CAD2). However, previous studies on Eucalyptus gunnii xylem showed the presence of an additional, structurally unrelated, monomeric CAD form named CAD1. This form reduces coniferaldehyde to coniferyl alcohol, but is inactive on sinapaldehyde. In this paper, we report the functional characterization of CAD1 in tobacco (Nicotiana tabacum L.). Transgenic tobacco plants with reduced CAD1 expression were obtained through an RNAi strategy. These plants displayed normal growth and development, and detailed biochemical studies were needed to reveal a role for CAD1. Lignin analyses showed that CAD1 down-regulation does not affect Klason lignin content, and has a moderate impact on G unit content of the non-condensed lignin fraction. However, comparative metabolic profiling of the methanol-soluble phenolic fraction from basal xylem revealed significant differences between CAD1 down-regulated and wild-type plants. Eight compounds were less abundant in CAD1 down-regulated lines, five of which were identified as dimers or trimers of monolignols, each containing at least one moiety derived from coniferyl alcohol. In addition, 3-trans-caffeoyl quinic acid accumulated in the transgenic plants. Together, our results support a significant contribution of CAD1 to the synthesis of coniferyl alcohol in planta, along with the previously characterized CAD2 enzymes.

Conifer flavonoid compounds inhibit detoxification enzymes and synergize insecticides.

Science.gov (United States)

Wang, Zhiling; Zhao, Zhong; Cheng, Xiaofei; Liu, Suqi; Wei, Qin; Scott, Ian M

2016-02-01

Detoxification by glutathione S-transferases (GSTs) and esterases are important mechanisms associated with insecticide resistance. Discovery of novel GST and esterase inhibitors from phytochemicals could provide potential new insecticide synergists. Conifer tree species contain flavonoids, such as taxifolin, that inhibit in vitro GST activity. The objectives were to test the relative effectiveness of taxifolin as an enzyme inhibitor and as an insecticide synergist in combination with the organophosphorous insecticide, Guthion (50% azinphos-methyl), and the botanical insecticide, pyrethrum, using an insecticide-resistant Colorado potato beetle (CPB) Leptinotarsa decemlineata (Say) strain. Both taxifolin and its isomer, quercetin, increased the mortality of 1(st) instar CPB larvae after 48h when combined with Guthion, but not pyrethrum. Taxifolin had greater in vitro esterase inhibition compared with the commonly used esterase inhibitor, S, S, S-tributyl phosphorotrithioate (DEF). An in vivo esterase and GST inhibition effect after ingestion of taxifolin was measured, however DEF caused a greater suppression of esterase activity. This study demonstrated that flavonoid compounds have both in vitro and in vivo esterase inhibition, which is likely responsible for the insecticide synergism observed in insecticide-resistant CPB. Crown Copyright © 2015. Published by Elsevier Inc. All rights reserved.

Scaling of phloem structure and optimality of photoassimilate transport in conifer needles

DEFF Research Database (Denmark)

Ronellenfitsch, Henrik; Liesche, Johannes; Jensen, Kaare Hartvig

2015-01-01

The phloem vascular system facilitates transport of energy-rich sugar and signalling molecules in plants, thus permitting long-range communication within the organism and growth of non-photosynthesizing organs such as roots and fruits. The flow is driven by osmotic pressure, generated...... by differences in sugar concentration between distal parts of the plant. The phloem is an intricate distribution system, and many questions about its regulation and structural diversity remain unanswered. Here, we investigate the phloem structure in the simplest possible geometry: a linear leaf, found......, for example, in the needles of conifer trees. We measure the phloem structure in four tree species representing a diverse set of habitats and needle sizes, from 1 (Picea omorika) to 35 cm (Pinus palustris). We show that the phloem shares common traits across these four species and find that the size of its...

Contrasting spatial patterns in active-fire and fire-suppressed Mediterranean climate old-growth mixed conifer forests.

Directory of Open Access Journals (Sweden)

Danny L Fry

Full Text Available In Mediterranean environments in western North America, historic fire regimes in frequent-fire conifer forests are highly variable both temporally and spatially. This complexity influenced forest structure and spatial patterns, but some of this diversity has been lost due to anthropogenic disruption of ecosystem processes, including fire. Information from reference forest sites can help management efforts to restore forests conditions that may be more resilient to future changes in disturbance regimes and climate. In this study, we characterize tree spatial patterns using four-ha stem maps from four old-growth, Jeffrey pine-mixed conifer forests, two with active-fire regimes in northwestern Mexico and two that experienced fire exclusion in the southern Sierra Nevada. Most of the trees were in patches, averaging six to 11 trees per patch at 0.007 to 0.014 ha(-1, and occupied 27-46% of the study areas. Average canopy gap sizes (0.04 ha covering 11-20% of the area were not significantly different among sites. The putative main effects of fire exclusion were higher densities of single trees in smaller size classes, larger proportion of trees (≥ 56% in large patches (≥ 10 trees, and decreases in spatial complexity. While a homogenization of forest structure has been a typical result from fire exclusion, some similarities in patch, single tree, and gap attributes were maintained at these sites. These within-stand descriptions provide spatially relevant benchmarks from which to manage for structural heterogeneity in frequent-fire forest types.

Comparison of ecosystem water flux measured with the Eddy covariance- and the direct xylem sap flux method in a mountainous forest

Energy Technology Data Exchange (ETDEWEB)

Stefanicki, G; Geissbuehler, P; Siegwolf, R [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

1999-08-01

The Eddy covariance technique allows to measure different components of turbulent air fluxes, including the flow of water vapour. Sap flux measurements determine directly the water flow in tree stems. We compared the water flux just above the crowns of trees in a forest by the technique of Eddy covariance and the water flux by the xylem sap flux method. These two completely different approaches showed a good qualitative correspondence. The correlation coefficient is 0.8. With an estimation of the crown diameter of the measured tree we also find a very good quantitative agreement. (author) 3 figs., 5 refs.

Conifers in decorative arboretum of Botanic Garden of Petrozavodsk State University

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Eglacheva Arina

2014-11-01

Full Text Available The transformation that taking place during of spontaneous cultivars introduction have not taken into consideration for last 10 years. The plants introduction in the Botanic Garden PSU have a planned character in a northwest middle taiga. Decorative arboretum was laid in 2000 (Potapova, Prokhorov, 2010. By 2014, the conifers collection includes 159 specimens of 98 cultivars belonging to 28 species, 10 genera and 3 families (Cupressaceae, Pinaceae, Taxaceae. Taxa are presented as species with narrow native habitat (Microbiota decussata, Thujopsis dolabrata, Chamaecyparis pisifera, Picea omorika, and with a wide (Juniperus communis. Plants were planted gradually. Annual plant monitoring include measuring of height, width of the crown, trunk diameter, needles color, seed-bearing, damage. Based on the study was identified plants groups in growth rate, seed-bearing. The number of generative samples are increased from 17 to 53% during 2007-2014. Seed-bearing is not a constant parameter and depends on a complex of abiotic factors.

The conifer biomarkers dehydroabietic and abietic acids are widespread in Cyanobacteria

Science.gov (United States)

Costa, Maria Sofia; Rego, Adriana; Ramos, Vitor; Afonso, Tiago B.; Freitas, Sara; Preto, Marco; Lopes, Viviana; Vasconcelos, Vitor; Magalhães, Catarina; Leão, Pedro N.

2016-01-01

Terpenes, a large family of natural products with important applications, are commonly associated with plants and fungi. The diterpenoids dehydroabietic and abietic acids are defense metabolites abundant in resin, and are used as biomarkers for conifer plants. We report here for the first time that the two diterpenoid acids are produced by members of several genera of cyanobacteria. Dehydroabietic acid was isolated from two cyanobacterial strains and its identity was confirmed spectroscopically. One or both of the diterpenoids were detected in the cells of phylogenetically diverse cyanobacteria belonging to four cyanobacterial ‘botanical orders’, from marine, estuarine and inland environments. Dehydroabietic acid was additionally found in culture supernatants. We investigated the natural role of the two resin acids in cyanobacteria using ecologically-relevant bioassays and found that the compounds inhibited the growth of a small coccoid cyanobacterium. The unexpected discovery of dehydroabietic and abietic acids in a wide range of cyanobacteria has implications for their use as plant biomarkers. PMID:26996104

Evolution of Conifer Diterpene Synthases: Diterpene Resin Acid Biosynthesis in Lodgepole Pine and Jack Pine Involves Monofunctional and Bifunctional Diterpene Synthases1[W][OA

Science.gov (United States)

Hall, Dawn E.; Zerbe, Philipp; Jancsik, Sharon; Quesada, Alfonso Lara; Dullat, Harpreet; Madilao, Lina L.; Yuen, Macaire; Bohlmann, Jörg

2013-01-01

Diterpene resin acids (DRAs) are major components of pine (Pinus spp.) oleoresin. They play critical roles in conifer defense against insects and pathogens and as a renewable resource for industrial bioproducts. The core structures of DRAs are formed in secondary (i.e. specialized) metabolism via cycloisomerization of geranylgeranyl diphosphate (GGPP) by diterpene synthases (diTPSs). Previously described gymnosperm diTPSs of DRA biosynthesis are bifunctional enzymes that catalyze the initial bicyclization of GGPP followed by rearrangement of a (+)-copalyl diphosphate intermediate at two discrete class II and class I active sites. In contrast, similar diterpenes of gibberellin primary (i.e. general) metabolism are produced by the consecutive activity of two monofunctional class II and class I diTPSs. Using high-throughput transcriptome sequencing, we discovered 11 diTPS from jack pine (Pinus banksiana) and lodgepole pine (Pinus contorta). Three of these were orthologous to known conifer bifunctional levopimaradiene/abietadiene synthases. Surprisingly, two sets of orthologous PbdiTPSs and PcdiTPSs were monofunctional class I enzymes that lacked functional class II active sites and converted (+)-copalyl diphosphate, but not GGPP, into isopimaradiene and pimaradiene as major products. Diterpene profiles and transcriptome sequences of lodgepole pine and jack pine are consistent with roles for these diTPSs in DRA biosynthesis. The monofunctional class I diTPSs of DRA biosynthesis form a new clade within the gymnosperm-specific TPS-d3 subfamily that evolved from bifunctional diTPS rather than monofunctional enzymes (TPS-c and TPS-e) of gibberellin metabolism. Homology modeling suggested alterations in the class I active site that may have contributed to their functional specialization relative to other conifer diTPSs. PMID:23370714

Thermal Acclimation of Photosynthesis and Respiration Differ Across Mature Conifer Species in a Boreal Forest Peatland

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Dusenge, M. E.; Stinziano, J. R.; Warren, J.; Ward, E. J.; Wullschleger, S.; Hanson, P. J.; Way, D.

2017-12-01

Boreal forests are often assumed to be temperature-limited, and warming is therefore expected to stimulate their carbon uptake. However, much of our information on the ability of boreal conifers to acclimate photosynthesis and respiration to rising temperatures comes from seedlings. We measured net CO2 assimilation rates (A) and dark respiration (R) at 25 °C (A25 and R25) and at prevailing growth temperatures (Ag and Rg) in mature Picea mariana (spruce) and Larix laricina (tamarack) exposed to ambient, +2.25, +4.5, +6.75 and +9 °C warming treatments in open top chambers in the field at the SPRUCE experiment (MN, USA). In spruce, A25 and Ag were similar across plots in May and June. In August, spruce in warmer treatments had higher A25, an effect that was offset by warmer leaf temperatures in the Ag data. In tamarack, A25 was stimulated by warming in both June and August, an effect that was mainly offset by higher leaf temperatures when Ag was assessed in June, while in August, Ag was still slightly higher in the warmest treatments (+6.75 and +9) compared to the ambient plots. In spruce, R25 was enhanced in warm-grown trees in May, but was similar across treatments in June and August, indicating little acclimation of R. Rg slightly increased with warming treatments across the season in spruce. In contrast, R in tamarack thermally acclimated, as R25 decreased with warming. But while this acclimation generated homeostatic Rg in June, Rg in August was still highest in the warmest treatments. Our work suggests that the capacity for thermal acclimation in both photosynthesis and respiration varies among boreal tree species, which may lead to shifts in the performance of these species as the climate warms.

Gap-based silviculture in a sierran mixed-conifer forest: effects of gap size on early survival and 7-year seedling growth

Science.gov (United States)

Robert A. York; John J. Battles; Robert C. Heald

2007-01-01

Experimental canopy gaps ranging in size from 0.1 to 1.0 ha (0.25 to 2.5 acres) were created in a mature mixed conifer forest at Blodgett Forest Research Station, California. Following gap creation, six species were planted in a wagon-wheel design and assessed for survival after two growing seasons. Study trees were measured after seven years to describe the effect of...

Rapid hydraulic recovery in Eucalyptus pauciflora after drought: linkages between stem hydraulics and leaf gas exchange.

Science.gov (United States)

Martorell, Sebastià; Diaz-Espejo, Antonio; Medrano, Hipólito; Ball, Marilyn C; Choat, Brendan

2014-03-01

In woody plants, photosynthetic capacity is closely linked to rates at which the plant hydraulic system can supply water to the leaf surface. Drought-induced embolism can cause sharp declines in xylem hydraulic conductivity that coincide with stomatal closure and reduced photosynthesis. Recovery of photosynthetic capacity after drought is dependent on restored xylem function, although few data exist to elucidate this coordination. We examined the dynamics of leaf gas exchange and xylem function in Eucalyptus pauciflora seedlings exposed to a cycle of severe water stress and recovery after re-watering. Stomatal closure and leaf turgor loss occurred at water potentials that delayed the extensive spread of embolism through the stem xylem. Stem hydraulic conductance recovered to control levels within 6 h after re-watering despite a severe drought treatment, suggesting an active mechanism embolism repair. However, stomatal conductance did not recover after 10 d of re-watering, effecting tighter control of transpiration post drought. The dynamics of recovery suggest that a combination of hydraulic and non-hydraulic factors influenced stomatal behaviour post drought. © 2013 John Wiley & Sons Ltd.

Arabidopsis VASCULAR-RELATED UNKNOWN PROTEIN1 Regulates Xylem Development and Growth by a Conserved Mechanism That Modulates Hormone Signaling1[W][OPEN

Science.gov (United States)

Grienenberger, Etienne; Douglas, Carl J.

2014-01-01

Despite a strict conservation of the vascular tissues in vascular plants (tracheophytes), our understanding of the genetic basis underlying the differentiation of secondary cell wall-containing cells in the xylem of tracheophytes is still far from complete. Using coexpression analysis and phylogenetic conservation across sequenced tracheophyte genomes, we identified a number of Arabidopsis (Arabidopsis thaliana) genes of unknown function whose expression is correlated with secondary cell wall deposition. Among these, the Arabidopsis VASCULAR-RELATED UNKNOWN PROTEIN1 (VUP1) gene encodes a predicted protein of 24 kD with no annotated functional domains but containing domains that are highly conserved in tracheophytes. Here, we show that the VUP1 expression pattern, determined by promoter-β-glucuronidase reporter gene expression, is associated with vascular tissues, while vup1 loss-of-function mutants exhibit collapsed morphology of xylem vessel cells. Constitutive overexpression of VUP1 caused dramatic and pleiotropic developmental defects, including severe dwarfism, dark green leaves, reduced apical dominance, and altered photomorphogenesis, resembling brassinosteroid-deficient mutants. Constitutive overexpression of VUP homologs from multiple tracheophyte species induced similar defects. Whole-genome transcriptome analysis revealed that overexpression of VUP1 represses the expression of many brassinosteroid- and auxin-responsive genes. Additionally, deletion constructs and site-directed mutagenesis were used to identify critical domains and amino acids required for VUP1 function. Altogether, our data suggest a conserved role for VUP1 in regulating secondary wall formation during vascular development by tissue- or cell-specific modulation of hormone signaling pathways. PMID:24567189

Haertel's turbidity test and extraction of conifer needles by benzene as methods for the determination of smoke-induced damage

Energy Technology Data Exchange (ETDEWEB)

Materna, J; Hrncirova, L

1960-01-01

The applicability of the Haertel turbidity test to the assessment of smoke damage to conifers is based on the observation that needles from smoke damage to conifers is based on the observation that needles from smoke-damaged areas eliminate less wax than undamaged needles. Of the various organic solvent and extraction methods tested, best results were obtained by a half-hour extraction of the wax from the needle surface with cold benzene. The evaporation residue from this extraction method contained only traces of components from the inside of the needles; microscopic examination of the surface of the needles revealed that all wax was removed from the needle surface fissures. Comparison of wax quantities extracted from needles from smoke-damage areas with those from healthy needles and comparison of wax yields from areas which suffered different degrees of smoke damage confirmed that higher wax yields are obtained from healthy than from smoke-damaged needles. Comparison with results of turbidity tests disclosed that benzene extraction yields decreased with increasing turbidity test values, indicating that increased turbidity of smoke-damaged needles is not caused by wax. In the Haertel test extract, silicon, calcium, magnesium, phosphorus, potassium, sulfur, iron, nitrogenous substances, tannin, glycides, and waxes were found. It is as yet unresolved which substances contribute to increased turbidity from smoke damage.

Seasonal and diel variation in xylem CO2 concentration and sap pH in sub-Mediterranean oak stems.

Science.gov (United States)

Salomón, Roberto; Valbuena-Carabaña, María; Teskey, Robert; McGuire, Mary Anne; Aubrey, Doug; González-Doncel, Inés; Gil, Luis; Rodríguez-Calcerrada, Jesús

2016-04-01

Since a substantial portion of respired CO2 remains within the stem, diel and seasonal trends in stem CO2 concentration ([CO2]) are of major interest in plant respiration and carbon budget research. However, continuous long-term stem [CO2] studies are scarce, and generally absent in Mediterranean climates. In this study, stem [CO2] was monitored every 15min together with stem and air temperature, sap flow, and soil water storage during a growing season in 16 stems of Quercus pyrenaica to elucidate the main drivers of stem [CO2] at different temporal scales. Fluctuations in sap pH were also assessed during two growing seasons to evaluate potential errors in estimates of the concentration of CO2 dissolved in xylem sap ([CO2*]) calculated using Henry's law. Stem temperature was the best predictor of stem [CO2] and explained more than 90% and 50% of the variability in stem [CO2] at diel and seasonal scales, respectively. Under dry conditions, soil water storage was the main driver of stem [CO2]. Likewise, the first rains after summer drought caused intense stem [CO2] pulses, suggesting enhanced stem and root respiration and increased resistance to radial CO2 diffusion. Sap flow played a secondary role in controlling stem [CO2] variations. We observed night-time sap pH acidification and progressive seasonal alkalinization. Thus, if the annual mean value of sap pH (measured at midday) was assumed to be constant, night-time sap [CO2*] was substantially overestimated (40%), and spring and autumn sap [CO2*] were misestimated by 25%. This work highlights that diel and seasonal variations in temperature, tree water availability, and sap pH substantially affect xylem [CO2] and sap [CO2*]. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Effects of diterpene acids on components of a conifer bark beetle-fungal interaction : tolerance by Ips pini and sensitivity by its associate Ophiostoma ips

Science.gov (United States)

Brian J. Kopper; Barbara L. Illman; Philip J. Kersten; Kier D. Klepzig; Kenneth F. Raffa

2005-01-01

Conifer resin and phloem tissue contain several phytochemical groups, composed primarily of monoterpenes, diterpene acids, and stilbene phenolics. The effects of monoterpenes and phenolics on stem-colonizing bark beetles and their associated microorganisms have been studied to some extent, but the roles of diterpene acids are largely unknown. Diterpene acids are known...

Effects of diterpene acids on components of a conifer bark beetle–fungal interaction: tolerance by Ips pini and sensitivity by its associate Ophiostoma ips

Science.gov (United States)

Brian J. Kopper; Barbara L. Illman; Philip J. Kersten; Kier D. Klepzig; Kenneth F. Raffa

2005-01-01

Conifer resin and phloem tissue contain several phytochemical groups,composed primarily of monoterpenes,diterpene acids, and stilbene phenolics. The effects of monoterpenes and phenolics on stem-colonizing bark beetles and their associated microorganisms have been studied to some extent, but the roles of diterpene acids are largely unknown. Diterpene acids are known to...

A Norway spruce FLOWERING LOCUS T homolog is implicated in control of growth rhythm in conifers.

Science.gov (United States)

Gyllenstrand, Niclas; Clapham, David; Källman, Thomas; Lagercrantz, Ulf

2007-05-01

Growth in perennial plants possesses an annual cycle of active growth and dormancy that is controlled by environmental factors, mainly photoperiod and temperature. In conifers and other nonangiosperm species, the molecular mechanisms behind these responses are currently unknown. In Norway spruce (Picea abies L. Karst.) seedlings, growth cessation and bud set are induced by short days and plants from southern latitudes require at least 7 to 10 h of darkness, whereas plants from northern latitudes need only 2 to 3 h of darkness. Bud burst, on the other hand, is almost exclusively controlled by temperature. To test the possible role of Norway spruce FLOWERING LOCUS T (FT)-like genes in growth rhythm, we have studied expression patterns of four Norway spruce FT family genes in two populations with a divergent bud set response under various photoperiodic conditions. Our data show a significant and tight correlation between growth rhythm (both bud set and bud burst), and expression pattern of one of the four Norway spruce phosphatidylethanolamine-binding protein gene family members (PaFT4) over a variety of experimental conditions. This study strongly suggests that one Norway spruce homolog to the FT gene, which controls flowering in angiosperms, is also a key integrator of photoperiodic and thermal signals in the control of growth rhythms in gymnosperms. The data also indicate that the divergent adaptive bud set responses of northern and southern Norway spruce populations, both to photoperiod and light quality, are mediated through PaFT4. These results provide a major advance in our understanding of the molecular control of a major adaptive trait in conifers and a tool for further molecular studies of adaptive variation in plants.

A blend of ethanol and (−)-α-pinene were highly attractive to native siricid woodwasps (Siricidae, Siricinae) infesting conifers of the Sierra Nevada and the Allegheny Mountains

Science.gov (United States)

Nadir Erbilgin; Jack D. Stein; Robert E. Acciavatti; Nancy E. Gillette; Sylvia R. Mori; Kristi Bischel; Jonathan A. Cale; Carline R. Carvalho; David L. Wood

2017-01-01

Woodwasps in Sirex and related genera are well-represented in North American conifer forests, but the chemical ecology of native woodwasps is limited to a few studies demonstrating their attraction to volatile host tree compounds, primarily monoterpene hydrocarbons and monoterpene alcohols. Thus, we...

Forest smoke damage symptomatalogy in the case of conifers

Energy Technology Data Exchange (ETDEWEB)

Halbwachs, G

1971-01-01

Due to their minor content of storage tissue and, therefore, reserve materials, their low capability for regeneration and the long life of their assimilation organs, conifers are among the most sensitive groups in respect to the impact of gaseous pollutants. Differences in the sensitivity of whole plants and assimilation organs necessitate a separate discussion of symptoms in needles and trees. Comparison of chronic and acute injuries in needles caused by sulfur dioxide, fluorine compounds and nitric oxides demonstrates that differences are not pronounced enough to be of value in differential diagnosis. Quite generally, acute injuries are characterized by tip necroses, which affect a different length of the terminal needle parts depending on the concentration of the pollutant. Effects on cell physiology are discussed in connection with the description of microscopic symptoms. Needle necroses as well as alterations of tree appearance are not specific for pollution effects, a number of other factors having been found to produce similar symptoms. So, symptoms can be regarded as characteristic, but not sufficiently distinct for an unequivocal diagnosis. An evaluation of symptoms proves very useful for pollution studies, however, in connection with other methods (e.g. chemical analysis of air or plant samples). 47 references.

Estimation and forecasting of the state of conifer forests in the area of the ChNPP accident

International Nuclear Information System (INIS)

Kozubov, G.M.; Taskaev, A.I.; Abaturov, Yu.D.

1989-01-01

Radiation monitoring of conifer forests was performed over the area of 15-20 hectare for all directions from the ChNPP. Biometric growth indices of pinetrees and sprucetrees during the period 1986-1988 were studied. The specific features of vegetative morphological changes in the mentioned trees were estimated for different absorbed dose rates. The quality factors of seeds were shown to be bioindicators of the absorbed doses in the case of highly chronic radiation injuries. In conclusion it was recommended to arrange a permanent radiation monitoring of radiation environment and to provide radiation protection of forests. figs. 2; tabs. 7

Understanding Seasonal Dynamics of the Photo-Protective Xanthophyll Cycle Improves Remote Detection of Photosynthetic Phenology in Deciduous Trees and Evergreen Conifers

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Ensminger, I.; Wong, C. Y.; Junker, L. V.; Bathena, Y.; Arain, M. A.; D'Odorico, P.

2017-12-01

The ability of plants to sequester carbon is highly variable over the course of the year and reflects seasonal variation in photosynthetic efficiency. This seasonal variation is most prominent during autumn, when leaves of deciduous tree species undergo senescence, which is associated with the downregulation of photosynthesis and a change of leaf color and leaf optical properties. Vegetation indices derived from remote sensing of leaf optical properties using e.g. spectral reflectance measurements are increasingly used to monitor and predict growing season length and seasonal variation in carbon sequestration. Here we compare leaf-level, canopy-level and drone based observations of leaf spectral reflectance measurements. We demonstrate that some of the widely used vegetation indices such as the normalized difference vegetation index (NDVI) and photochemical reflectance index (PRI) vary in their ability to adequately track the seasonal variation in photosynthetic efficiency and chlorophyll content. We further show that monitoring seasonal variation of photosynthesis using NDVI or PRI is particularly challenging in evergreen conifers, due to little seasonal variation in foliage. However, there is remarkable seasonal variation in leaf optical properties associated with changes in pools of xanthophyll cycle pigments and carotenoids that provide a promising way of monitoring photosynthetic phenology in evergreen conifers via leaf reflectance measurements.

Macro-scale assessment of demographic and environmental variation within genetically derived evolutionary lineages of eastern hemlock (Tsuga canadensis), an imperiled conifer of the eastern United States

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Anantha M. Prasad; Kevin M. Potter

2017-01-01

Eastern hemlock (Tsuga canadensis) occupies a large swath of eastern North America and has historically undergone range expansion and contraction resulting in several genetically separate lineages. This conifer is currently experiencing mortality across most of its range following infestation of a non-native insect. With the goal of better...

Old Growth Conifer Watersheds in the Western Cascades, Oregon: Sentinels of Climate Change

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Miles, K. M.

2011-12-01

In the Pacific Northwest, where the majority of precipitation falls during the winter, mountain snowpacks provide an important source of streamflow during the dry summer months when water demands are frequently highest. Increasing temperatures associated with climate change are expected to result in a decline in winter snowpacks in western North America, earlier snowmelt, and subsequently a shift in the timing of streamflows, with an increasing fraction of streamflows occurring earlier in the water year and drier conditions during the summer. Long-term records from headwater watersheds in old growth conifer forest at the H. J. Andrews Experimental Forest (HJ Andrews), Oregon, provide the opportunity to examine changes in climate, vegetation, and streamflow. Continuous streamflow records have been collected since 1953, 1964, and 1969 from three small (8.5-60 ha) watersheds (WS2, WS8, and WS9). Over the 40- to 50-year period of study, late winter to early summer monthly average minimum temperatures have increased by 1-2°C, and spring snow water equivalent at a nearby Snotel site has declined, but monthly precipitation has remained unchanged. Spring runoff ratios have declined in by amounts equivalent to 0.59-2.45 mm day-1 at WS2, WS8, and WS9, which are comparable to estimated rates of stand-level transpiration from trees in these watersheds. However, winter runoff ratios have not changed significantly at either WS2 or WS9, and have actually decreased at WS8 by 2.43 mm day-1 over the period of record. Furthermore, summer runoff ratios have not changed significantly at either WS8 or WS9, and have increased at WS2 by 0.34 mm day-1 over the period of record. These findings suggest that warming temperatures have resulted in a reduction in spring snowpacks and an earlier onset of evapotranspiration in the spring when soil moisture is abundant, but physiological responses of these conifer forests to water stress and water surplus may mitigate or exceed the expression of a

A comprehensive guide to fuel management practices for dry mixed conifer forests in the northwestern United States: Mechanical, chemical, and biological fuel treatment methods

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Theresa B. Jain; Mike A. Battaglia; Han-Sup Han; Russell T. Graham; Christopher R. Keyes; Jeremy S. Fried; Jonathan E. Sandquist

2014-01-01

Several mechanical approaches to managing vegetation fuels hold promise when applied to the dry mixed conifer forests in the western United States. These are most useful to treat surface, ladder, and crown fuels. There are a variety of techniques to remove or alter all kinds of plant biomass (live, dead, or decomposed) that affect forest resilience. It is important for...

Effect of air pollution on the epiphytic flora of conifers in the Stockholm region

Energy Technology Data Exchange (ETDEWEB)

Lundstroem, H

1968-01-01

Epiphytic flora (especially lichens) have been investigated in order to see how they respond to air pollution. The study was restricted to those occurring up to a height of 2.3 m from the ground, on trunks of the conifers Picea abies and Pinus silvestries. The area of investigation lies north of Stockholm. Wind diagrams show a slight predominance of winds from Stockholm. This means that polluted air is spread out over the area of investigation. All epiphytic vegetation on the station-trees for which the species were determined are listed. The distribution of lichen species is discussed, especially how air pollution has affected the distributions of the three lichens, Hypogymnia physodes (L.) Zopf (syn. Parmelia physodes (L.) Ach.) Parmeliopsis ambigua (Wulf) Nyl. Pseudevernia furfuraceae (L.) Zopf (syn. Parmelia furfuraceae (L.) Ach.). Maps of distributions have been made for the most common epiphytes.

Machine vision system for measuring conifer seedling morphology

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Rigney, Michael P.; Kranzler, Glenn A.

1995-01-01

A PC-based machine vision system providing rapid measurement of bare-root tree seedling morphological features has been designed. The system uses backlighting and a 2048-pixel line- scan camera to acquire images with transverse resolutions as high as 0.05 mm for precise measurement of stem diameter. Individual seedlings are manually loaded on a conveyor belt and inspected by the vision system in less than 0.25 seconds. Designed for quality control and morphological data acquisition by nursery personnel, the system provides a user-friendly, menu-driven graphical interface. The system automatically locates the seedling root collar and measures stem diameter, shoot height, sturdiness ratio, root mass length, projected shoot and root area, shoot-root area ratio, and percent fine roots. Sample statistics are computed for each measured feature. Measurements for each seedling may be stored for later analysis. Feature measurements may be compared with multi-class quality criteria to determine sample quality or to perform multi-class sorting. Statistical summary and classification reports may be printed to facilitate the communication of quality concerns with grading personnel. Tests were conducted at a commercial forest nursery to evaluate measurement precision. Four quality control personnel measured root collar diameter, stem height, and root mass length on each of 200 conifer seedlings. The same seedlings were inspected four times by the machine vision system. Machine stem diameter measurement precision was four times greater than that of manual measurements. Machine and manual measurements had comparable precision for shoot height and root mass length.

Areas of Agreement and Disagreement Regarding Ponderosa Pine and Mixed Conifer Forest Fire Regimes: A Dialogue with Stevens et al.

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Dennis C Odion

Full Text Available In a recent PLOS ONE paper, we conducted an evidence-based analysis of current versus historical fire regimes and concluded that traditionally defined reference conditions of low-severity fire regimes for ponderosa pine (Pinus ponderosa and mixed-conifer forests were incomplete, missing considerable variability in forest structure and fire regimes. Stevens et al. (this issue agree that high-severity fire was a component of these forests, but disagree that one of the several sources of evidence, stand age from a large number of forest inventory and analysis (FIA plots across the western USA, support our findings that severe fire played more than a minor role ecologically in these forests. Here we highlight areas of agreement and disagreement about past fire, and analyze the methods Stevens et al. used to assess the FIA stand-age data. We found a major problem with a calculation they used to conclude that the FIA data were not useful for evaluating fire regimes. Their calculation, as well as a narrowing of the definition of high-severity fire from the one we used, leads to a large underestimate of conditions consistent with historical high-severity fire. The FIA stand age data do have limitations but they are consistent with other landscape-inference data sources in supporting a broader paradigm about historical variability of fire in ponderosa and mixed-conifer forests than had been traditionally recognized, as described in our previous PLOS paper.

Areas of Agreement and Disagreement Regarding Ponderosa Pine and Mixed Conifer Forest Fire Regimes: A Dialogue with Stevens et al.

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Odion, Dennis C; Hanson, Chad T; Baker, William L; DellaSala, Dominick A; Williams, Mark A

2016-01-01

In a recent PLOS ONE paper, we conducted an evidence-based analysis of current versus historical fire regimes and concluded that traditionally defined reference conditions of low-severity fire regimes for ponderosa pine (Pinus ponderosa) and mixed-conifer forests were incomplete, missing considerable variability in forest structure and fire regimes. Stevens et al. (this issue) agree that high-severity fire was a component of these forests, but disagree that one of the several sources of evidence, stand age from a large number of forest inventory and analysis (FIA) plots across the western USA, support our findings that severe fire played more than a minor role ecologically in these forests. Here we highlight areas of agreement and disagreement about past fire, and analyze the methods Stevens et al. used to assess the FIA stand-age data. We found a major problem with a calculation they used to conclude that the FIA data were not useful for evaluating fire regimes. Their calculation, as well as a narrowing of the definition of high-severity fire from the one we used, leads to a large underestimate of conditions consistent with historical high-severity fire. The FIA stand age data do have limitations but they are consistent with other landscape-inference data sources in supporting a broader paradigm about historical variability of fire in ponderosa and mixed-conifer forests than had been traditionally recognized, as described in our previous PLOS paper.

Fire impact on carbon storage in light conifer forests of the Lower Angara region, Siberia

International Nuclear Information System (INIS)

Ivanova, G A; Kukavskaya, E A; Conard, S G; McRae, D J

2011-01-01

This study focused on structural analysis of ground carbon storage following fires in light conifer stands of the Lower Angara region (Siberia, Russia). Experimental fires of varying frontal intensity were conducted at Scots pine and mixed larch forests of southern taiga. Considerable amounts of surface and ground forest fuels (21–38 tC ha −1 ) enhanced low- to high-intensity fires. Post-fire carbon storage decreased by 16–49% depending on fire intensity and rate of spread, with depth of burn being 0.9–6.6 cm. Carbon emissions varied from 4.48 to 15.89 t ha −1 depending on fire intensity and forest type. Depth of burn and carbon emissions for four major site types were correlated with a weather-based fire hazard index.

Climate sensitivity of reproduction in a mast-seeding boreal conifer across its distributional range from lowland to treeline forests.

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Roland, Carl A; Schmidt, Joshua H; Johnstone, Jill F

2014-03-01

Mast-seeding conifers such as Picea glauca exhibit synchronous production of large seed crops over wide areas, suggesting climate factors as possible triggers for episodic high seed production. Rapidly changing climatic conditions may thus alter the tempo and spatial pattern of masting of dominant species with potentially far-reaching ecological consequences. Understanding the future reproductive dynamics of ecosystems including boreal forests, which may be dominated by mast-seeding species, requires identifying the specific cues that drive variation in reproductive output across landscape gradients and among years. Here we used annual data collected at three sites spanning an elevation gradient in interior Alaska, USA between 1986 and 2011 to produce the first quantitative models for climate controls over both seedfall and seed viability in P. glauca, a dominant boreal conifer. We identified positive associations between seedfall and increased summer precipitation and decreased summer warmth in all years except for the year prior to seedfall. Seed viability showed a contrasting response, with positive correlations to summer warmth in all years analyzed except for one, and an especially positive response to warm and wet conditions in the seedfall year. Finally, we found substantial reductions in reproductive potential of P. glauca at high elevation due to significantly reduced seed viability there. Our results indicate that major variation in the reproductive potential of this species may occur in different landscape positions in response to warming, with decreasing reproductive success in areas prone to drought stress contrasted with increasing success in higher elevation areas currently limited by cool summer temperatures.

How to make a tree ring: Coupling stem water flow and cambial activity in mature Alpine conifers

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Peters, Richard L.; Frank, David C.; Treydte, Kerstin; Steppe, Kathy; Kahmen, Ansgar; Fonti, Patrick

2017-04-01

Inter-annual tree-ring measurements are used to understand tree-growth responses to climatic variability and reconstruct past climate conditions. In parallel, mechanistic models use experimentally defined plant-atmosphere interactions to explain past growth responses and predict future environmental impact on forest productivity. Yet, substantial inconsistencies within mechanistic model ensembles and mismatches with empirical data indicate that significant progress is still needed to understand the processes occurring at an intra-annual resolution that drive annual growth. However, challenges arise due to i) few datasets describing climatic responses of high-resolution physiological processes over longer time-scales, ii) uncertainties on the main mechanistic process limiting radial stem growth and iii) complex interactions between multiple environmental factors which obscure detection of the main stem growth driver, generating a gap between our understanding of intra- and inter-annual growth mechanisms. We attempt to bridge the gap between inter-annual tree-ring width and sub-daily radial stem-growth and provide a mechanistic perspective on how environmental conditions affect physiological processes that shape tree rings in conifers. We combine sub-hourly sap flow and point dendrometer measurements performed on mature Alpine conifers (Larix decidua) into an individual-based mechanistic tree-growth model to simulate sub-hourly cambial activity. The monitored trees are located along a high elevational transect in the Swiss Alps (Lötschental) to analyse the effect of increasing temperature. The model quantifies internal tree hydraulic pathways that regulate the turgidity within the cambial zone and induce cell enlargement for radial growth. The simulations are validated against intra-annual growth patterns derived from xylogenesis data and anatomical analyses. Our efforts advance the process-based understanding of how climate shapes the annual tree-ring structures

Thinning, tree-growth, and resistance to multi-year drought in a mixed-conifer forest of northern California

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Vernon, Michael J.; Sherriff, Rosemary L.; van Mantgem, Phillip; Kane, Jeffrey M.

2018-01-01

Drought is an important stressor in forest ecosystems that can influence tree vigor and survival. In the U.S., forest managers use two primary management techniques to promote resistance and resilience to drought: prescribed fire and mechanical thinning. Generally applied to reduce fuels and fire hazard, treatments may also reduce competition for resources that may improve tree-growth and reduce mortality during drought. A recent severe and prolonged drought in California provided a natural experiment to investigate tree-growth responses to fuel treatments and climatic stress. We assessed tree-growth from 299 ponderosa pine (Pinus ponderosa) and Douglas-fir (Pseudotsuga menziesii) in treated and untreated stands during severe drought from 2012 to 2015 in the mixed-conifer forests of Whiskeytown National Recreation Area (WNRA) in northern California. The treatment implemented at WNRA removed 34% of live basal area through mechanical thinning with a subsequent pile burning of residual fuels. Tree-growth was positively associated with crown ratio and negatively associated with competition and a 1-year lag of climate water deficit, an index of drought. Douglas-fir generally had higher annual growth than ponderosa pine, although factors affecting growth were the same for both species. Drought resistance, expressed as the ratio between mean growth during drought and mean growth pre-drought, was higher in treated stands compared to untreated stands during both years of severe drought (2014 and 2015) for ponderosa pine but only one year (2014) for Douglas-fir. Thinning improved drought resistance, but tree size, competition and species influenced this response. On-going thinning treatments focused on fuels and fire hazard reduction are likely to be effective at promoting growth and greater drought resistance in dry mixed-conifer forests. Given the likelihood of future droughts, land managers may choose to implement similar treatments to reduce potential impacts.

A Norway Spruce FLOWERING LOCUS T Homolog Is Implicated in Control of Growth Rhythm in Conifers1[OA

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Gyllenstrand, Niclas; Clapham, David; Källman, Thomas; Lagercrantz, Ulf

2007-01-01

Growth in perennial plants possesses an annual cycle of active growth and dormancy that is controlled by environmental factors, mainly photoperiod and temperature. In conifers and other nonangiosperm species, the molecular mechanisms behind these responses are currently unknown. In Norway spruce (Picea abies L. Karst.) seedlings, growth cessation and bud set are induced by short days and plants from southern latitudes require at least 7 to 10 h of darkness, whereas plants from northern latitudes need only 2 to 3 h of darkness. Bud burst, on the other hand, is almost exclusively controlled by temperature. To test the possible role of Norway spruce FLOWERING LOCUS T (FT)-like genes in growth rhythm, we have studied expression patterns of four Norway spruce FT family genes in two populations with a divergent bud set response under various photoperiodic conditions. Our data show a significant and tight correlation between growth rhythm (both bud set and bud burst), and expression pattern of one of the four Norway spruce phosphatidylethanolamine-binding protein gene family members (PaFT4) over a variety of experimental conditions. This study strongly suggests that one Norway spruce homolog to the FT gene, which controls flowering in angiosperms, is also a key integrator of photoperiodic and thermal signals in the control of growth rhythms in gymnosperms. The data also indicate that the divergent adaptive bud set responses of northern and southern Norway spruce populations, both to photoperiod and light quality, are mediated through PaFT4. These results provide a major advance in our understanding of the molecular control of a major adaptive trait in conifers and a tool for further molecular studies of adaptive variation in plants. PMID:17369429

Structures of Bordered Pits Potentially Contributing to Isolation of a Refilled Vessel from Negative Xylem Pressure in Stems of Morus australis Poir.: Testing of the Pit Membrane Osmosis and Pit Valve Hypotheses.

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Ooeda, Hiroki; Terashima, Ichiro; Taneda, Haruhiko

2017-02-01

Two hypotheses have been proposed to explain the mechanism preventing the refilling vessel water from being drained to the neighboring functional vessels under negative pressure. The pit membrane osmosis hypothesis proposes that the xylem parenchyma cells release polysaccharides that are impermeable to the intervessel pit membranes into the refilling vessel; this osmotically counteracts the negative pressure, thereby allowing the vessel to refill. The pit valve hypothesis proposes that gas trapped within intervessel bordered pits isolates the refilling vessel water from the surrounding functional vessels. Here, using the single-vessel method, we assessed these hypotheses in shoots of mulberry (Morus australis Poir.). First, we confirmed the occurrence of xylem refilling under negative pressure in the potted mulberry saplings. To examine the pit membrane osmosis hypothesis, we estimated the semi-permeability of pit membranes for molecules of various sizes and found that the pit membranes were not semi-permeable to polyethylene glycol of molecular mass osmosis mechanism in mulberry would be unrealistically large. © The Author 2016. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Distribution of pines in the Iberian Peninsula agrees with species differences in foliage frost tolerance, not with vulnerability to freezing-induced xylem embolism.

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Fernández-Pérez, Laura; Villar-Salvador, Pedro; Martínez-Vilalta, Jordi; Toca, Andrei; Zavala, Miguel A

2018-04-01

Drought and frosts are major determinants of plant functioning and distribution. Both stresses can cause xylem embolism and foliage damage. The objective of this study was to analyse if the distribution of six common pine species along latitudinal and altitudinal gradients in Europe is related to their interspecific differences in frost tolerance and to the physiological mechanisms underlying species-specific frost tolerance. We also evaluate if frost tolerance depends on plant water status. We studied survival to a range of freezing temperatures in 2-year-old plants and assessed the percentage loss of hydraulic conductivity (PLC) due xylem embolism formation and foliage damage determined by needle electrolyte leakage (EL) after a single frost cycle to -15 °C and over a range of predawn water potential (ψpd) values. Species experiencing cold winters in their range (Pinus nigra J.F. Arnold, Pinus sylvestris L. and Pinus uncinata Raymond ex A. DC.) had the highest frost survival rates and lowest needle EL and soluble sugar (SS) concentration. In contrast, the pines inhabiting mild or cool winter locations (especially Pinus halepensis Mill. and Pinus pinea L. and, to a lesser extent, Pinus pinaster Ait.) had the lowest frost survival and highest needle EL and SS values. Freezing-induced PLC was very low and differences among species were not related to frost damage. Reduction in ψpd decreased leaf frost damage in P. pinea and P. sylvestris, increased it in P. uncinata and had a neutral effect on the rest of the species. This study demonstrates that freezing temperatures are a major environmental driver for pine distribution and suggests that interspecific differences in leaf frost sensitivity rather than vulnerability to freezing-induced embolism or SS explain pine juvenile frost survival.

Development of 23 novel polymorphic EST-SSR markers for the endangered relict conifer Metasequoia glyptostroboides.

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Jin, Yuqing; Bi, Quanxin; Guan, Wenbin; Mao, Jian-Feng

2015-09-01

Metasequoia glyptostroboides is an endangered relict conifer species endemic to China. In this study, expressed sequence tag-simple sequence repeat (EST-SSR) markers were developed using transcriptome mining for future genetic and functional studies. We collected 97,565 unigene sequences generated by 454 pyrosequencing. A bioinformatics analysis identified 2087 unique and putative microsatellites, from which 96 novel microsatellite markers were developed. Fifty-three of the 96 primer sets successfully amplified clear fragments of the expected sizes; 23 of those loci were polymorphic. The number of alleles per locus ranged from two to eight, with an average of three, and the observed and expected heterozygosity values ranged from 0 to 1.0 and 0.117 to 0.813, respectively. These microsatellite loci will enrich the genetic resources to develop functional studies and conservation strategies for this endangered relict species.

Change in hydraulic properties and leaf traits of a tall rainforest tree species subjected to long-term throughfall exclusion in the perhumid tropics

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Schuldt, B.; Leuschner, C.; Horna, V.; Moser, G.; Köhler, M.; Barus, H.

2010-11-01

In a throughfall displacement experiment on Sulawesi, Indonesia, three 0.16 ha stands of a premontane perhumid rainforest were exposed to a two-year soil desiccation period that reduced the soil moisture in the upper soil layers beyond the conventional wilting point. About 25 variables, including leaf morphological and chemical traits, stem diameter growth and hydraulic properties of the xylem in the trunk and terminal twigs, were investigated in trees of the tall-growing tree species Castanopsis acuminatissima (Fagaceae) by comparing desiccated roof plots with nearby control plots. We tested the hypotheses that this tall and productive species is particularly sensitive to drought, and the exposed upper sun canopy is more affected than the shade canopy. Hydraulic conductivity in the xylem of terminal twigs normalised to vessel lumen area was reduced by 25%, leaf area-specific conductivity by 10-33% during the desiccation treatment. Surprisingly, the leaves present at the end of the drought treatment were significantly larger, but not smaller in the roof plots, though reduced in number (about 30% less leaves per unit of twig sapwood area), which points to a drought effect on the leaf bud formation while the remaining leaves may have profited from a surplus of water. Mean vessel diameter and axial conductivity in the outermost xylem of the trunk were significantly reduced and wood density increased, while annual stem diameter increment decreased by 26%. In contradiction to our hypotheses, (i) we found no signs of major damage to the C. acuminatissima trees nor to any other drought sensitivity of tall trees, and (ii) the exposed upper canopy was not more drought susceptible than the shade canopy.

Ion-mediated enhancement of xylem hydraulic conductivity in four Acer species: relationships with ecological and anatomical features.

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Nardini, Andrea; Dimasi, Federica; Klepsch, Matthias; Jansen, Steven

2012-12-01

The 'ionic effect', i.e., changes in xylem hydraulic conductivity (k(xyl)) due to variation of the ionic sap composition in vessels, was studied in four Acer species growing in contrasting environments differing in water availability. Hydraulic measurements of the ionic effect were performed together with measurements on the sap electrical conductivity, leaf water potential and vessel anatomy. The low ionic effect recorded in Acer pseudoplatanus L. and Acer campestre L. (15.8 and 14.7%, respectively), which represented two species from shady and humid habitats, was associated with a low vessel grouping index, high sap electrical conductivity and least negative leaf water potential. Opposite traits were found for Acer monspessulanum L. and Acer platanoides L., which showed an ionic effect of 23.6 and 23.1%, respectively, and represent species adapted to higher irradiance and/or lower water availability. These findings from closely related species provide additional support that the ionic effect could function as a compensation mechanism for embolism-induced loss of k(xyl), either as a result of high evaporative demand or increased risk of hydraulic failure.

Differences in the response sensitivity of stomatal index to atmospheric CO2 among four genera of Cupressaceae conifers.

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Haworth, Matthew; Heath, James; McElwain, Jennifer C

2010-03-01

The inverse relationship between stomatal density (SD: number of stomata per mm(2) leaf area) and atmospheric concentration of CO2 ([CO2]) permits the use of plants as proxies of palaeo-atmospheric CO2. Many stomatal reconstructions of palaeo-[CO2] are based upon multiple fossil species. However, it is unclear how plants respond to [CO2] across genus, family or ecotype in terms of SD or stomatal index (SI: ratio of stomata to epidermal cells). This study analysed the stomatal numbers of conifers from the ancient family Cupressaceae, in order to examine the nature of the SI-[CO2] relationship, and potential implications for stomatal reconstructions of palaeo-[CO2]. Methods Stomatal frequency measurements were taken from historical herbarium specimens of Athrotaxis cupressoides, Tetraclinis articulata and four Callitris species, and live A. cupressoides grown under CO2-enrichment (370, 470, 570 and 670 p.p.m. CO2). T. articulata, C. columnaris and C. rhomboidea displayed significant reductions in SI with rising [CO2]; by contrast, A. cupressoides, C. preissii and C. oblonga show no response in SI. However, A. cupressoides does reduce SI to increases in [CO2] above current ambient (approx. 380 p.p.m. CO2). This dataset suggests that a shared consistent SI-[CO2] relationship is not apparent across the genus Callitris. Conclusions The present findings suggest that it is not possible to generalize how conifer species respond to fluctuations in [CO2] based upon taxonomic relatedness or habitat. This apparent lack of a consistent response, in conjunction with high variability in SI, indicates that reconstructions of absolute palaeo-[CO2] based at the genus level, or upon multiple species for discrete intervals of time are not as reliable as those based on a single or multiple temporally overlapping species.

Leaf Area Prediction Using Three Alternative Sampling Methods for Seven Sierra Nevada Conifer Species

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Dryw A. Jones

2015-07-01

Full Text Available Prediction of projected tree leaf area using allometric relationships with sapwood cross-sectional area is common in tree- and stand-level production studies. Measuring sapwood is difficult and often requires destructive sampling. This study tested multiple leaf area prediction models across seven diverse conifer species in the Sierra Nevada of California. The best-fit whole tree leaf area prediction model for overall simplicity, accuracy, and utility for all seven species was a nonlinear model with basal area as the primary covariate. A new non-destructive procedure was introduced to extend the branch summation approach to leaf area data collection on trees that cannot be destructively sampled. There were no significant differences between fixed effects assigned to sampling procedures, indicating that data from the tested sampling procedures can be combined for whole tree leaf area modeling purposes. These results indicate that, for the species sampled, accurate leaf area estimates can be obtained through partially-destructive sampling and using common forest inventory data.

Estimating canopy bulk density and canopy base height for conifer stands in the interior Western United States using the Forest Vegetation Simulator Fire and Fuels Extension.

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Seth Ex; Frederick Smith; Tara Keyser; Stephanie Rebain

2017-01-01

The Forest Vegetation Simulator Fire and Fuels Extension (FFE-FVS) is often used to estimate canopy bulk density (CBD) and canopy base height (CBH), which are key indicators of crown fire hazard for conifer stands in the Western United States. Estimated CBD from FFE-FVS is calculated as the maximum 4 m running mean bulk density of predefined 0.3 m thick canopy layers (...

Molecular control of normal and acrocona mutant seed cone development in Norway spruce (Picea abies) and the evolution of conifer ovule-bearing organs.

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Carlsbecker, Annelie; Sundström, Jens F; Englund, Marie; Uddenberg, Daniel; Izquierdo, Liz; Kvarnheden, Anders; Vergara-Silva, Francisco; Engström, Peter

2013-10-01

Reproductive organs in seed plants are morphologically divergent and their evolutionary history is often unclear. The mechanisms controlling their development have been extensively studied in angiosperms but are poorly understood in conifers and other gymnosperms. Here, we address the molecular control of seed cone development in Norway spruce, Picea abies. We present expression analyses of five novel MADS-box genes in comparison with previously identified MADS and LEAFY genes at distinct developmental stages. In addition, we have characterized the homeotic transformation from vegetative shoot to female cone and associated changes in regulatory gene expression patterns occurring in the acrocona mutant. The analyses identified genes active at the onset of ovuliferous and ovule development and identified expression patterns marking distinct domains of the ovuliferous scale. The reproductive transformation in acrocona involves the activation of all tested genes normally active in early cone development, except for an AGAMOUS-LIKE6/SEPALLATA (AGL6/SEP) homologue. This absence may be functionally associated with the nondeterminate development of the acrocona ovule-bearing scales. Our morphological and gene expression analyses give support to the hypothesis that the modern cone is a complex structure, and the ovuliferous scale the result of reductions and compactions of an ovule-bearing axillary short shoot in cones of Paleozoic conifers. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

Sequence/structural analysis of xylem proteome emphasizes pathogenesis-related proteins, chitinases and β-1, 3-glucanases as key players in grapevine defense against Xylella fastidiosa

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Sandeep Chakraborty

2016-05-01

Full Text Available Background. Xylella fastidiosa, the causative agent of various plant diseases including Pierce’s disease in the US, and Citrus Variegated Chlorosis in Brazil, remains a continual source of concern and economic losses, especially since almost all commercial varieties are sensitive to this Gammaproteobacteria. Differential expression of proteins in infected tissue is an established methodology to identify key elements involved in plant defense pathways. Methods. In the current work, we developed a methodology named CHURNER that emphasizes relevant protein functions from proteomic data, based on identification of proteins with similar structures that do not necessarily have sequence homology. Such clustering emphasizes protein functions which have multiple copies that are up/down-regulated, and highlights similar proteins which are differentially regulated. As a working example we present proteomic data enumerating differentially expressed proteins in xylem sap from grapevines that were infected with X. fastidiosa. Results. Analysis of this data by CHURNER highlighted pathogenesis related PR-1 proteins, reinforcing this as the foremost protein function in xylem sap involved in the grapevine defense response to X. fastidiosa. β-1, 3-glucanase, which has both anti-microbial and anti-fungal activities, is also up-regulated. Simultaneously, chitinases are found to be both up and down-regulated by CHURNER, and thus the net gain of this protein function loses its significance in the defense response. Discussion. We demonstrate how structural data can be incorporated in the pipeline of proteomic data analysis prior to making inferences on the importance of individual proteins to plant defense mechanisms. We expect CHURNER to be applicable to any proteomic data set.

Why are the seed cones of conifers so diverse at pollination?

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Losada, Juan M; Leslie, Andrew B

2018-03-08

Form and function relationships in plant reproductive structures have long fascinated biologists. Although the intricate associations between specific pollinators and reproductive morphology have been widely explored among animal-pollinated plants, the evolutionary processes underlying the diverse morphologies of wind-pollinated plants remain less well understood. Here we study how this diversity may have arisen by focusing on two conifer species in the pine family that have divergent reproductive cone morphologies at pollination. Standard histology methods, artificial wind pollination assays and phylogenetic analyses were used in this study. A detailed study of cone ontogeny in these species reveals that variation in the rate at which their cone scales mature means that pollination occurs at different stages in their development, and thus in association with different specific morphologies. Pollination experiments nevertheless indicate that both species effectively capture pollen. In wind-pollinated plants, morphological diversity may result from simple variation in development among lineages rather than selective pressures for any major differences in function or performance. This work also illustrates the broader importance of developmental context in understanding plant form and function relationships; because plant reproductive structures perform many different functions over their lifetime, subtle differences in development may dramatically alter the specific morphologies that they use to meet these demands.

Studying global change through investigation of the plastic responses of xylem anatomy in tree rings.

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Fonti, Patrick; von Arx, Georg; García-González, Ignacio; Eilmann, Britta; Sass-Klaassen, Ute; Gärtner, Holger; Eckstein, Dieter

2010-01-01

Variability in xylem anatomy is of interest to plant scientists because of the role water transport plays in plant performance and survival. Insights into plant adjustments to changing environmental conditions have mainly been obtained through structural and functional comparative studies between taxa or within taxa on contrasting sites or along environmental gradients. Yet, a gap exists regarding the study of hydraulic adjustments in response to environmental changes over the lifetimes of plants. In trees, dated tree-ring series are often exploited to reconstruct dynamics in ecological conditions, and recent work in which wood-anatomical variables have been used in dendrochronology has produced promising results. Environmental signals identified in water-conducting cells carry novel information reflecting changes in regional conditions and are mostly related to short, sub-annual intervals. Although the idea of investigating environmental signals through wood anatomical time series goes back to the 1960s, it is only recently that low-cost computerized image-analysis systems have enabled increased scientific output in this field. We believe that the study of tree-ring anatomy is emerging as a promising approach in tree biology and climate change research, particularly if complemented by physiological and ecological studies. This contribution presents the rationale, the potential, and the methodological challenges of this innovative approach.

Frost fatigue and spring recovery of xylem vessels in three diffuse-porous trees in situ.

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Christensen-Dalsgaard, Karen K; Tyree, Melvin T

2014-05-01

Frost has been shown to cause frost fatigue (reduced cavitation resistance) in branch segments in the lab. Here, we studied the change in cavitation resistance and percent loss of conductivity (PLC) from fall to spring over 2 consecutive years in three diffuse-porous species in situ. We used the cavitron technique to measure P25 , P50 and P90 (the xylem pressure causing a 25, 50 and 90% conductivity loss) and PLC and stained functioning vessels. Cavitation resistance was reduced by 64-87% (in terms of P50 ), depending on the species and year. P25 was impacted the most and P90 the least, changing the vulnerability curves from s- to r-shaped over the winter in all three species. The branches suffered an almost complete loss of conductivity, but frost fatigue did not necessarily occur concurrently with increases in PLC. In two species, there was a trade-off between conduit size and vulnerability. Spring recovery occurred by growth of new vessels, and in two species by partial refilling of embolized conduits. Although newly grown and functioning conduits appeared more vulnerable to cavitation than year-old vessels, cavitation resistance generally improved in spring, suggesting other mechanisms for partial frost fatigue repair. © 2013 John Wiley & Sons Ltd.

Red Xylem and Higher Lignin Extractability by Down-Regulating a Cinnamyl Alcohol Dehydrogenase in Poplar.

Science.gov (United States)

Baucher, M.; Chabbert, B.; Pilate, G.; Van Doorsselaere, J.; Tollier, M. T.; Petit-Conil, M.; Cornu, D.; Monties, B.; Van Montagu, M.; Inze, D.; Jouanin, L.; Boerjan, W.

1996-12-01

Cinnamyl alcohol dehydrogenase (CAD) catalyzes the last step in the biosynthesis of the lignin precursors, the monolignols. We have down-regulated CAD in transgenic poplar (Populus tremula X Populus alba) by both antisense and co-suppression strategies. Several antisense and sense CAD transgenic poplars had an approximately 70% reduced CAD activity that was associated with a red coloration of the xylem tissue. Neither the lignin amount nor the lignin monomeric composition (syringyl/guaiacyl) were significantly modified. However, phloroglucinol-HCl staining was different in the down-regulated CAD plants, suggesting changes in the number of aldehyde units in the lignin. Furthermore, the reactivity of the cell wall toward alkali treatment was altered: a lower amount of lignin was found in the insoluble, saponified residue and more lignin could be precipitated from the soluble alkali fraction. Moreover, large amounts of phenolic compounds, vanillin and especially syringaldehyde, were detected in the soluble alkali fraction of the CAD down-regulated poplars. Alkaline pulping experiments on 3-month-old trees showed a reduction of the kappa number without affecting the degree of cellulose degradation. These results indicate that reducing the CAD activity in trees might be a valuable strategy to optimize certain processes of the wood industry, especially those of the pulp and paper industry.

Seed crop size variation in the dominant South American conifer Araucaria angustifolia

Science.gov (United States)

Souza, Alexandre F.; Uarte de Matos, Daniele; Forgiarini, Cristiane; Martinez, Jaime

2010-01-01

Temporal variation in seed crop size of the long-lived pioneer conifer Araucaria angustifolia was studied in subtropical South America. We evaluated the expectations that: 1) A. angustifolia presents highly variable seed production (mast seeding behavior); 2) A. angustifolia has endogenous cycles of reproduction of two or three years; 3) There is a tendency for a high seed production year to be followed by an unusually low production year; 4) populations show synchrony in seed production at a geographical scale; 5) seed crop size is influenced by distinct climatic factors occurring during "key" reproductive stages and 6) as an expression of plant productivity, seed crop size should depend on integrated resource availability during the reproductive cycle. We obtained data from two distinct sources: 1) seed harvesting records from a private forest (14 years), and 2) commercial data from 22 municipalities in the Rio Grande do Sul State. Expectations 1, 2, 3 and 5 were not met, while expectations 4 and 6 were supported by the data. A. angustifolia showed environmentally triggered, continuous, moderately fluctuating, and regionally synchronous reproduction. Seed set seems to track variations in resource abundance as well as respond continuously to improved opportunities for successful regeneration.

Multi-scale predictions of massive conifer mortality due to chronic temperature rise

Science.gov (United States)

McDowell, N. G.; Williams, A. P.; Xu, C.; Pockman, W. T.; Dickman, L. T.; Sevanto, S.; Pangle, R.; Limousin, J.; Plaut, J.; Mackay, D. S.; Ogee, J.; Domec, J. C.; Allen, C. D.; Fisher, R. A.; Jiang, X.; Muss, J. D.; Breshears, D. D.; Rauscher, S. A.; Koven, C.

2016-03-01

Global temperature rise and extremes accompanying drought threaten forests and their associated climatic feedbacks. Our ability to accurately simulate drought-induced forest impacts remains highly uncertain in part owing to our failure to integrate physiological measurements, regional-scale models, and dynamic global vegetation models (DGVMs). Here we show consistent predictions of widespread mortality of needleleaf evergreen trees (NET) within Southwest USA by 2100 using state-of-the-art models evaluated against empirical data sets. Experimentally, dominant Southwest USA NET species died when they fell below predawn water potential (Ψpd) thresholds (April-August mean) beyond which photosynthesis, hydraulic and stomatal conductance, and carbohydrate availability approached zero. The evaluated regional models accurately predicted NET Ψpd, and 91% of predictions (10 out of 11) exceeded mortality thresholds within the twenty-first century due to temperature rise. The independent DGVMs predicted >=50% loss of Northern Hemisphere NET by 2100, consistent with the NET findings for Southwest USA. Notably, the global models underestimated future mortality within Southwest USA, highlighting that predictions of future mortality within global models may be underestimates. Taken together, the validated regional predictions and the global simulations predict widespread conifer loss in coming decades under projected global warming.

Whitebark pine facilitation at treeline: potential interactions for disruption by an invasive pathogen.

Science.gov (United States)

Tomback, Diana F; Blakeslee, Sarah C; Wagner, Aaron C; Wunder, Michael B; Resler, Lynn M; Pyatt, Jill C; Diaz, Soledad

2016-08-01

In stressful environments, facilitation often aids plant establishment, but invasive plant pathogens may potentially disrupt these interactions. In many treeline communities in the northern Rocky Mountains of the U.S. and Canada, Pinus albicaulis, a stress-tolerant pine, initiates tree islands at higher frequencies than other conifers - that is, leads to leeward tree establishment more frequently. The facilitation provided by a solitary (isolated) P. albicaulis leading to tree island initiation may be important for different life-history stages for leeward conifers, but it is not known which life-history stages are influenced and protection provided. However, P. albicaulis mortality from the non-native pathogen Cronartium ribicola potentially disrupts these facilitative interactions, reducing tree island initiation. In two Rocky Mountain eastern slope study areas, we experimentally examined fundamental plant-plant interactions which might facilitate tree island formation: the protection offered by P. albicaulis to leeward seed and seedling life-history stages, and to leeward krummholz conifers. In the latter case, we simulated mortality from C. ribicola for windward P. albicaulis to determine whether loss of P. albicaulis from C. ribicola impacts leeward conifers. Relative to other common solitary conifers at treeline, solitary P. albicaulis had higher abundance. More seeds germinated in leeward rock microsites than in conifer or exposed microsites, but the odds of cotyledon seedling survival during the growing season were highest in P. albicaulis microsites. Planted seedling survival was low among all microsites examined. Simulating death of windward P. albicaulis by C. ribicola reduced shoot growth of leeward trees. Loss of P. albicaulis to exotic disease may limit facilitation interactions and conifer community development at treeline and potentially impede upward movement as climate warms.

Cavitation of intercellular spaces is critical to establishment of hydraulic properties of compression wood of Chamaecyparis obtusa seedlings.

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Nakaba, Satoshi; Hirai, Asami; Kudo, Kayo; Yamagishi, Yusuke; Yamane, Kenichi; Kuroda, Katsushi; Nugroho, Widyanto Dwi; Kitin, Peter; Funada, Ryo

2016-03-01

When the orientation of the stems of conifers departs from the vertical as a result of environmental influences, conifers form compression wood that results in restoration of verticality. It is well known that intercellular spaces are formed between tracheids in compression wood, but the function of these spaces remains to be clarified. In the present study, we evaluated the impact of these spaces in artificially induced compression wood in Chamaecyparis obtusa seedlings. We monitored the presence or absence of liquid in the intercellular spaces of differentiating xylem by cryo-scanning electron microscopy. In addition, we analysed the relationship between intercellular spaces and the hydraulic properties of the compression wood. Initially, we detected small intercellular spaces with liquid in regions in which the profiles of tracheids were not rounded in transverse surfaces, indicating that the intercellular spaces had originally contained no gases. In the regions where tracheids had formed secondary walls, we found that some intercellular spaces had lost their liquid. Cavitation of intercellular spaces would affect hydraulic conductivity as a consequence of the induction of cavitation in neighbouring tracheids. Our observations suggest that cavitation of intercellular spaces is the critical event that affects not only the functions of intercellular spaces but also the hydraulic properties of compression wood. © The Author 2016. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

PpNAC1, a main regulator of phenylalanine biosynthesis and utilization in maritime pine.

Science.gov (United States)

Pascual, María Belén; Llebrés, María-Teresa; Craven-Bartle, Blanca; Cañas, Rafael A; Cánovas, Francisco M; Ávila, Concepción

2018-05-01

The transcriptional regulation of phenylalanine metabolism is particularly important in conifers, long-lived species that use large amounts of carbon in wood. Here, we show that the Pinus pinaster transcription factor, PpNAC1, is a main regulator of phenylalanine biosynthesis and utilization. A phylogenetic analysis classified PpNAC1 in the NST proteins group and was selected for functional characterization. PpNAC1 is predominantly expressed in the secondary xylem and compression wood of adult trees. Silencing of PpNAC1 in P. pinaster results in the alteration of stem vascular radial patterning and the down-regulation of several genes associated with cell wall biogenesis and secondary metabolism. Furthermore, transactivation and EMSA analyses showed that PpNAC1 is able to activate its own expression and PpMyb4 promoter, while PpMyb4 is able to activate PpMyb8, a transcriptional regulator of phenylalanine and lignin biosynthesis in maritime pine. Together, these results suggest that PpNAC1 is a functional ortholog of the ArabidopsisSND1 and NST1 genes and support the idea that key regulators governing secondary cell wall formation could be conserved between gymnosperms and angiosperms. Understanding the molecular switches controlling wood formation is of paramount importance for fundamental tree biology and paves the way for applications in conifer biotechnology. © 2017 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.

High-performance liquid chromatography-atmospheric pressure chemical ionization mass spectrometry and gas chromatography-flame ionization detection chracterization of delta 5-polyenoic fatty acids in triacylglycerols from conifer seed oils

Czech Academy of Sciences Publication Activity Database

Lísa, M.; Holčapek, M.; Řezanka, Tomáš; Kabátová, N.

2007-01-01

Roč. 1146, - (2007), s. 67-77 ISSN 0021-9673 R&D Projects: GA ČR GA203/06/0219 Grant - others:GA ČR(CZ) GA203/05/2106 Program:GA Institutional research plan: CEZ:AV0Z50200510 Keywords : conifer seed oil * triacylglycerol * triglyceride Subject RIV: EE - Microbiology, Virology Impact factor: 3.641, year: 2007

Back to the Future: Building resilience in Colorado Front Range forests using research findings and a new guide for restoration of ponderosa and dry-mixed conifer landscapes

Science.gov (United States)

Sue Miller; Rob Addington; Greg Aplet; Mike Battaglia; Tony Cheng; Jonas Feinstein; Jeff Underhill

2018-01-01

Historically, the ponderosa and dry mixed-conifer forests of the Colorado Front Range were more open and grassy, and trees of all size classes were found in a grouped arrangement with sizable openings between the clumps. As a legacy of fire suppression, today’s forests are denser, with smaller trees. Proactive restoration of this forest type will help to reduce fuel...

Simple method for direct crown base height estimation of individual conifer trees using airborne LiDAR data.

Science.gov (United States)

Luo, Laiping; Zhai, Qiuping; Su, Yanjun; Ma, Qin; Kelly, Maggi; Guo, Qinghua

2018-05-14

Crown base height (CBH) is an essential tree biophysical parameter for many applications in forest management, forest fuel treatment, wildfire modeling, ecosystem modeling and global climate change studies. Accurate and automatic estimation of CBH for individual trees is still a challenging task. Airborne light detection and ranging (LiDAR) provides reliable and promising data for estimating CBH. Various methods have been developed to calculate CBH indirectly using regression-based means from airborne LiDAR data and field measurements. However, little attention has been paid to directly calculate CBH at the individual tree scale in mixed-species forests without field measurements. In this study, we propose a new method for directly estimating individual-tree CBH from airborne LiDAR data. Our method involves two main strategies: 1) removing noise and understory vegetation for each tree; and 2) estimating CBH by generating percentile ranking profile for each tree and using a spline curve to identify its inflection points. These two strategies lend our method the advantages of no requirement of field measurements and being efficient and effective in mixed-species forests. The proposed method was applied to a mixed conifer forest in the Sierra Nevada, California and was validated by field measurements. The results showed that our method can directly estimate CBH at individual tree level with a root-mean-squared error of 1.62 m, a coefficient of determination of 0.88 and a relative bias of 3.36%. Furthermore, we systematically analyzed the accuracies among different height groups and tree species by comparing with field measurements. Our results implied that taller trees had relatively higher uncertainties than shorter trees. Our findings also show that the accuracy for CBH estimation was the highest for black oak trees, with an RMSE of 0.52 m. The conifer species results were also good with uniformly high R 2 ranging from 0.82 to 0.93. In general, our method has

Transport and partitioning of CO2 fixed by root nodules of ureide and amide producing legumes

International Nuclear Information System (INIS)

Vance, C.P.; Boylan, K.L.M.; Maxwell, C.A.; Heichel, G.H.; Hardman, L.L.

1985-01-01

Nodulated and denodulated roots of adzuki bean (Vigna angularis), soybean (Glycine max), and alfalfa (Medicago sativa) were exposed to 14 CO 2 to investigate the contribution of nodule CO 2 fixation to assimilation and transport of fixed nitrogen. The distribution of radioactivity in xylem sap and partitioning of carbon fixed by nodules to the whole plant were measured. Radioactivity in the xylem sap of nodulated soybean and adzuki bean was located primarily (70 to 87%) in the acid fraction while the basic (amino acid) fraction contained 10 to 22%. In contrast radioactivity in the xylem sap of nodulated alfalfa was primarily in amino acids with about 20% in organic acids. Total ureide concentration was 8.1, 4.7, and 0.0 micromoles per milliliter xylem sap for soybean, adzuki bean, and alfalfa, respectively. While the major nitrogen transport products in soybeans and adzuki beans are ureides, this class of metabolites contained less than 20% of the the total radioactivity. When nodules of plants were removed, radioactivity in xylem sap decreased by 90% or more. Pulse-chase experiments indicated that CO 2 fixed by nodules was rapidly transported to shoots and incorporated into acid stable constituents. The data are consistent with a role for nodule CO 2 fixation providing carbon for the assimilation and transport of fixed nitrogen in amide-based legumes. In contrast, CO 2 fixation by nodules of ureide transporting legumes appears to contribute little to assimilation and transport of fixed nitrogen. 19 references, 2 figures, 5 tables

The accumulation pattern of ferruginol in the heartwood-forming Cryptomeria japonica xylem as determined by time-of-flight secondary ion mass spectrometry and quantity analysis

Science.gov (United States)

Kuroda, Katsushi; Fujiwara, Takeshi; Hashida, Koh; Imai, Takanori; Kushi, Masayoshi; Saito, Kaori; Fukushima, Kazuhiko

2014-01-01

Background and Aims Heartwood formation is a unique phenomenon of tree species. Although the accumulation of heartwood substances is a well-known feature of the process, the accumulation mechanism remains unclear. The aim of this study was to determine the accumulation process of ferruginol, a predominant heartwood substance of Cryptomeria japonica, in heartwood-forming xylem. Methods The radial accumulation pattern of ferruginol was examined from sapwood and through the intermediate wood to the heartwood by direct mapping using time-of-flight secondary ion mass spectrometry (TOF-SIMS). The data were compared with quantitative results obtained from a novel method of gas chromatography analysis using laser microdissection sampling and with water distribution obtained from cryo-scanning electron microscopy. Key Results Ferruginol initially accumulated in the middle of the intermediate wood, in the earlywood near the annual ring boundary. It accumulated throughout the entire earlywood in the inner intermediate wood, and in both the earlywood and the latewood in the heartwood. The process of ferruginol accumulation continued for more than eight annual rings. Ferruginol concentration peaked at the border between the intermediate wood and heartwood, while the concentration was less in the latewood compared wiht the earlywood in each annual ring. Ferruginol tended to accumulate around the ray parenchyma cells. In addition, at the border between the intermediate wood and heartwood, the accumulation was higher in areas without water than in areas with water. Conclusions TOF-SIMS clearly revealed ferruginol distribution at the cellular level. Ferruginol accumulation begins in the middle of intermediate wood, initially in the earlywood near the annual ring boundary, then throughout the entire earlywood, and finally across to the whole annual ring in the heartwood. The heterogeneous timing of ferruginol accumulation could be related to the distribution of ray parenchyma cells

Analysis of the Phlebiopsis gigantea Genome, Transcriptome and Secretome Provides Insight into Its Pioneer Colonization Strategies of Wood

Science.gov (United States)

Chiaki Hori; Takuya Ishida; Kiyohiko Igarashi; Masahiro Samejima; Hitoshi Suzuki; Emma Master; Patricia Ferreira; Francisco J. Ruiz-Duenas; Benjamin Held; Paulo Canessa; Luis F. Larrondo; Monika Schmoll; Irina S. Druzhinina; Christian P. Kubicek; Jill A. Gaskell; Phil Kersten; Franz St. John; Jeremy Glasner; Grzegorz Sabat; Sandra Splinter Bondurant; Khajamohiddin Syed; Jagjit Yadav; Anthony C. Mgbeahuruike; Andriy Kovalchuk; Fred O. Asiegbu; Gerald Lackner; Dirk Hoffmeister; Jorge Recoret; Ana Gutierrez; Hui Sun; Erika Lindquist; Kerrie Barry; Robert Riley; Igor V. Grigoriev; Bernard Henrissat; Ursula Kues; Randy M. Berka; Angel T. Martinez; Sarah F. Covert; Robert A. Blanchette; Daniel Cullen

2014-01-01

Collectively classified as white-rot fungi, certain basidiomycetes efficiently degrade the major structural polymers of wood cell walls. A small subset of these Agaricomycetes, exemplified by Phlebiopsis gigantea, is capable of colonizing freshly exposed conifer sapwood despite its high content of extractives, which retards the establishment of other...