WorldWideScience

Sample records for meristems

  1. Grass meristems II: inflorescence architecture, flower development and meristem fate.

    Science.gov (United States)

    Tanaka, Wakana; Pautler, Michael; Jackson, David; Hirano, Hiro-Yuki

    2013-03-01

    Plant development depends on the activity of various types of meristems that generate organs such as leaves and floral organs throughout the life cycle. Grass species produce complex inflorescences and unique flowers. The grass inflorescence is composed of different types of branches, including a specialized branch called a spikelet. The spikelet is a special unit of the inflorescence and forms one to several florets, depending on the species. In the floret, floral organs such as perianth organs, carpels and stamens are formed. In Arabidopsis, because the inflorescence meristem (IM) forms the floral meristems (FMs) directly on its flanks, the change of meristem fate is relatively simple. In contrast, in grasses, different types of meristem, such as the IM, the branch meristem (BM), the spikelet pair meristem (SPM) in some grasses, the spikelet meristem (SM) and the FM, are responsible for the elaboration of their complex inflorescences and flowers. Therefore, sequential changes of meristem fate are required, and a number of genes involved in the specification of the fate of each meristem have been identified. In this review, we focus on the following issues concerning the fate of the reproductive meristems in two grass species, maize (Zea mays) and rice (Oryza sativa): (i) meristem regulation during inflorescence development; (ii) specification and fate change of the BM and the SM; (iii) determinacy of the FM; and (iv) communication between the meristem and lateral organs.

  2. Effects of gamma radiation on potato meristems

    International Nuclear Information System (INIS)

    Fernandez Gonzalez, J.; Garcia Collantes, M.A.

    1976-01-01

    The development of buds in potato tubers subjected to gamma radiation at doses of 3, 6, 8 and 12 Krad is studied at histological level. The irradiation was supplied at the beguining and end of the resting period, and the irradiated buds were observed at different stages of their development. Meristem's sensitivity depends on the state of activity involved at the moment of irradiation. Different parts of the meristem present different radiosensitivity, being the most radioresistant. (author) [es

  3. Meristem maturation and inflorescence architecture--lessons from the Solanaceae.

    Science.gov (United States)

    Park, Soon Ju; Eshed, Yuval; Lippman, Zachary B

    2014-02-01

    Plant apical meristems (AMs) grow continuously by delicately balancing cells leaving at the periphery to form lateral organs with slowly dividing central domain cells that replenish reservoirs of pluripotent cells. This balance can be modified by signals originating from within and outside the meristem, and their integration results in a gradual maturation process that often culminates with the meristem differentiating into a flower. Accompanying this 'meristem maturation' are changes in spacing and size of lateral organs and in rates at which lateral meristems are released from apical dominance. Modulation of distinct meristem maturation parameters through environmental and genetic changes underlies the remarkable diversity of shoot architectures. Here, we discuss recent studies relating the dynamics of meristem maturation with organization of floral branching systems--inflorescences--in the nightshades. From this context, we suggest general principles on how factors coordinating meristem maturation impact shoot organization more broadly. Published by Elsevier Ltd.

  4. Meristem identity and phyllotaxis in inflorescence development

    Directory of Open Access Journals (Sweden)

    Madelaine Elisabeth Bartlett

    2014-10-01

    Full Text Available Inflorescence morphology is incredibly diverse. This diversity of form has been a fruitful source of inquiry for plant morphologists for more than a century. Work in the grasses (Poaceae, the tomato family (Solanaceae, and Arabidopsis (Brassicaceae has led to a richer understanding of the molecular genetics underlying this diversity. The character of individual meristems, a combination of the number (determinacy and nature (identity of the products a meristem produces, is key in the development of plant form. A framework that describes inflorescence development in terms of shifting meristem identities has emerged and garnered empirical support in a number of model systems. We discuss this framework and highlight one important aspect of meristem identity that is often considered in isolation, phyllotaxis. Phyllotaxis refers to the arrangement of lateral organs around a central axis. The development and evolution of phyllotaxis in the inflorescence remains underexplored, but recent work analyzing early inflorescence development in the grasses identified an evolutionary shift in primary branch phyllotaxis in the Pooideae. We discuss the evidence for an intimate connection between meristem identity and phyllotaxis in both the inflorescence and vegetative shoot, and touch on what is known about the establishment of phyllotactic patterns in the meristem. Localized auxin maxima are instrumental in determining the position of lateral primordia. Upstream factors that regulate the position of these maxima remain unclear, and how phyllotactic patterns change over the course of a plant’s lifetime and evolutionary time, is largely unknown. A more complete understanding of the molecular underpinnings of phyllotaxis and architectural diversity in inflorescences will require capitalizing on the extensive resources available in existing genetic systems, and developing new model systems that more fully represent the diversity of plant morphology.

  5. Potential bud bank responses to apical meristem damage and environmental variables: matching or complementing axillary meristems?

    Directory of Open Access Journals (Sweden)

    Jitka Klimešová

    Full Text Available Soil nutrients, dormant axillary meristem availability, and competition can influence plant tolerance to damage. However, the role of potential bud banks (adventitious meristems initiated only after injury is not known. Examining Central European field populations of 22 species of short-lived monocarpic herbs exposed to various sources of damage, we hypothesized that: (1 with increasing injury severity, the number of axillary branches would decrease, due to axillary meristem limitation, whereas the number of adventitious shoots (typically induced by severe injury would increase; (2 favorable environmental conditions would allow intact plants to branch more, resulting in stronger axillary meristem limitation than in unfavorable conditions; and (3 consequently, adventitious sprouting would be better enabled in favorable than unfavorable conditions. We found strong support for the first hypothesis, only limited support for the second, and none for the third. Our results imply that whereas soil nutrients and competition marginally influence plant tolerance to damage, potential bud banks enable plants to overcome meristem limitation from severe damage, and therefore better tolerate it. All the significant effects were found in intraspecific comparisons, whereas interspecific differences were not found. Monocarpic plants with potential bud banks therefore represent a distinct strategy occupying a narrow environmental niche. The disturbance regime typical for this niche remains to be examined, as do the costs associated with the banks of adventitious and axillary reserve meristems.

  6. Potential Bud Bank Responses to Apical Meristem Damage and Environmental Variables: Matching or Complementing Axillary Meristems?

    Czech Academy of Sciences Publication Activity Database

    Klimešová, Jitka; Malíková, Lenka; Rosenthal, J.; Šmilauer, P.

    2014-01-01

    Roč. 9, č. 2 (2014), e88093 E-ISSN 1932-6203 R&D Projects: GA ČR GPP504/12/P540; GA ČR GA526/09/0963 Institutional support: RVO:67985939 Keywords : bud bank * axillary meristem * disturbance Subject RIV: EH - Ecology, Behaviour Impact factor: 3.234, year: 2014

  7. Use of Petunia to unravel plant meristem functioning

    NARCIS (Netherlands)

    Angenent, G.C.; Stuurman, J.; Snowden, K.C.; Koes, R.E.

    2005-01-01

    In the past decade, enormous progress has been made in our understanding of the molecular and genetic control of meristem growth, maintenance and differentiation into plant organs. Several model plants have contributed to our current knowledge of meristem function. Research using Petunia has had a

  8. Salt stress affects the redox status of Arabidopsis root meristems

    Directory of Open Access Journals (Sweden)

    Keni eJiang

    2016-02-01

    Full Text Available We report the redox status (profiles for specific populations of cells that comprise the Arabidopsis root tip. For recently germinated, 3-5-day-old seedlings we show that the region of the root tip with the most reduced redox status includes the root cap initials, the quiescent center and the most distal portion of the proximal meristem, and coincides with (overlays the region of the auxin maximum. As one moves basally, further into the proximal meristem, and depending on the growth conditions, the redox status becomes more oxidized, with a 5-10 mV difference in redox potential between the two borders delimiting the proximal meristem. At the point on the root axis at which cells of the proximal meristem cease division and enter the transition zone, the redox potential levels off and remains more or less unchanged throughout the transition zone. As cells leave the transition zone and enter the zone of elongation the redox potentials become more oxidized. Treating roots with salt (50, 100 and 150 mM NaCl results in marked changes in root meristem structure and development, and is preceded by changes in the redox profile, which flattens, and initially becomes more oxidized, with pronounced changes in the redox potentials of the root cap, the root cap initials and the quiescent center. Roots exposed to relatively mild levels of salt (< 100 mM are able to re-establish a normal, pre-salt treatment redox profile 3-6 days after exposure to salt. Coincident with the salt-associated changes in redox profiles are changes in the distribution of auxin transporters (AUX1, PIN1/2, which become more diffuse in their localization. We conclude that salt stress affects root meristem maintenance, in part, through changes in redox and auxin transport.

  9. Sugar-Mediated Acclimation: The Importance of Sucrose Metabolism in Meristems

    NARCIS (Netherlands)

    Carpentier, S.C.; Vertommen, A.; Swennen, R.; Witters, E.; Fortes, C.; Souza, M.T.; Panis, B.

    2010-01-01

    We have designed an in vitro experimental setup to study the role of sucrose in sugar-mediated acclimation of banana meristems using established highly proliferating meristem cultures. It is a first step toward the systems biology of a meristem and the understanding of how it can survive severe

  10. Shoot apical meristem arrest in brassica and tomato

    NARCIS (Netherlands)

    Jonge, de J.

    2013-01-01

    A pool of cells known as stem cells located in the center of the shoot apical meristem (SAM) are responsible to maintain meristematic activity throughout a plants life in order to produce organs. The maintenance of these stem cells is tightly controlled by a complex genetic and hormonal network. Any

  11. Transcript profiling of a novel plant meristem, the monocot cambium

    Science.gov (United States)

    Matthew Zinkgraf; Suzanne Gerttula; Andrew Groover

    2017-01-01

    While monocots lack the ability to produce a vascular cambium or woody growth, some monocot lineages evolved a novel lateral meristem, the monocot cambium, which supports secondary radial growth of stems. In contrast to the vascular cambium found in woody angiosperm and gymnosperm species, the monocot cambium produces secondary vascular bundles, which have an...

  12. Shoot and plantlet regeneration from meristems of Dioscorea ...

    African Journals Online (AJOL)

    In vitro culture media capable of regenerating moderate to high shoots and/or plantlets from meristems of two yam species – Dioscorea rotundata and Dioscorea alata within comparable duration of 10 weeks as commonly obtained in other monocots and root and tuber crops were investigated. The study comprised 125 ...

  13. Three Arabidopsis AIL/PLT genes act in combination to regulate shoot apical meristem function.

    Science.gov (United States)

    Mudunkothge, Janaki S; Krizek, Beth A

    2012-07-01

    The shoot apical meristem, a small dome-shaped structure at the shoot apex, is responsible for the initiation of all post-embryonic shoot organs. Pluripotent stem cells within the meristem replenish themselves and provide daughter cells that become incorporated into lateral organ primordia around the meristem periphery. We have identified three novel regulators of shoot apical meristem activity in Arabidopsis thaliana that encode related AIL/PLT transcription factors: AINTEGUMENTA (ANT), AINTEGUMENTA-LIKE6 (AIL6)/PLETHORA3 (PLT3) and AINTEGUMENTA-LIKE7 (AIL7)/PLETHORA7 (PLT7). Loss of these genes results in plants that initiate only a few leaves prior to termination of shoot apical meristem activity. In 7-day-old ant ail6 ail7 seedlings, we observed reduced cell division in the meristem region, differentiation of meristematic cells and altered expression of the meristem regulators WUSCHEL (WUS), CLAVATA3 (CLV3) and SHOOT MERISTEMLESS (STM). Genetic experiments suggest that these three AIL genes do not act specifically in either the WUS/CLV or STM pathway regulating meristem function. Furthermore, these studies indicate that ANT, AIL6 and AIL7 have distinct functions within the meristem rather than acting in a strictly redundant manner. Our study thus identifies three new genes whose distinct functions are together required for continuous shoot apical meristem function. © 2012 The Authors. The Plant Journal © 2012 Blackwell Publishing Ltd.

  14. Diversity of Maize Shoot Apical Meristem Architecture and Its Relationship to Plant Morphology

    Science.gov (United States)

    Thompson, Addie M.; Yu, Jianming; Timmermans, Marja C. P.; Schnable, Patrick; Crants, James E.; Scanlon, Michael J.; Muehlbauer, Gary J.

    2015-01-01

    The shoot apical meristem contains a pool of undifferentiated stem cells and controls initiation of all aerial plant organs. In maize (Zea mays), leaves are formed throughout vegetative development; on transition to floral development, the shoot meristem forms the tassel. Due to the regulated balance between stem cell maintenance and organogenesis, the structure and morphology of the shoot meristem are constrained during vegetative development. Previous work identified loci controlling meristem architecture in a recombinant inbred line population. The study presented here expanded on this by investigating shoot apical meristem morphology across a diverse set of maize inbred lines. Crosses of these lines to common parents showed varying phenotypic expression in the F1, with some form of heterosis occasionally observed. An investigation of meristematic growth throughout vegetative development in diverse lines linked the timing of reproductive transition to flowering time. Phenotypic correlations of meristem morphology with adult plant traits showed an association between the meristem and flowering time, leaf shape, and yield traits, revealing links between the control and architecture of undifferentiated and differentiated plant organs. Finally, quantitative trait loci mapping was utilized to map the genetic architecture of these meristem traits in two divergent populations. Control of meristem architecture was mainly population-specific, with 15 total unique loci mapped across the two populations with only one locus identified in both populations. PMID:25748433

  15. Plasticity in Meristem Allocation as an Adaptive Strategy of a Desert Shrub under Contrasting Environments

    Directory of Open Access Journals (Sweden)

    Weiwei She

    2017-11-01

    Full Text Available The pattern of resource allocation to reproduction vs. vegetative growth is a core component of a plant’s life-history strategy. Plants can modify their biomass allocation patterns to adapt to contrasting environments. Meristems can have alternative fates to commit to vegetative growth, reproduction, or remaining inactive (dormant or senescent/dead. However, knowledge about whether meristem fates can interpret adaptive changes in biomass allocation remains largely unknown. We measured aboveground plant biomass (a proxy of plant size and meristem number of a dominant shrub Artemisia ordosica in three populations occupying different habitats in the Mu Us Desert of northern China. Size-dependent biomass allocation and meristem allocation among habitats were compared. The size-dependent biomass allocation and meristem allocation of A. ordosica strongly varied across habitats. There were significant positive linear relationships between meristem allocation and biomass allocation in all habitats, indicating that meristem allocation is an indicator of the estimated resource allocation to reproductive and vegetative organs in this species. Plasticity in meristem allocation was more likely caused by larger individuals having less active meristems due to environmental stress. Vegetative meristems (VM were likely more vulnerable to environmental limitation than reproductive ones, resulting in the ratio of resource investment between vegetative and reproductive functions exhibiting plasticity in different habitats. A. ordosica invested a higher fraction of its resource to reproduction in the adverse habitat, while more resource to vegetative growth in the favorable habitat. A. ordosica adopts different resource allocation patterns to adapt to contrasting habitat conditions through altering its meristem fates. Our results suggest that the arid-adapted shrub A. ordosica deactivates more VM than reproductive ones to hedge against environmental stress

  16. Phytoplasmal infection derails genetically preprogrammed meristem fate and alters plant architecture.

    Science.gov (United States)

    Wei, Wei; Davis, Robert Edward; Nuss, Donald L; Zhao, Yan

    2013-11-19

    In the life cycle of higher plants, it is the fate of meristem cells that determines the pattern of growth and development, and therefore plant morphotype and fertility. Floral transition, the turning point from vegetative growth to reproductive development, is achieved via genetically programmed sequential changes in meristem fate from vegetative to inflorescence, and to floral, leading to flower formation and eventual seed production. The transition is rarely reversible once initiated. In this communication, we report that a bacterial infection can derail the genetically programmed fate of meristem cells, thereby drastically altering the growth pattern of the host plant. We identified four characteristic symptoms in tomato plants infected with a cell wall-less bacterium, phytoplasma. The symptoms are a manifestation of the pathogen-induced alterations of growth pattern, whereas each symptom corresponds to a distinct phase in the derailment of shoot apical meristem fate. The phases include premature floral meristem termination, suppressed floral meristem initiation, delayed conversion of vegetative meristem to inflorescence meristem, and repetitive initiation and outgrowth of lateral vegetative meristems. We further found that the pathogen-induced alterations of growth pattern were correlated with transcriptional reprogramming of key meristem switching genes. Our findings open an avenue toward understanding pathological alterations in patterns of plant growth and development, thus aiding identification of molecular targets for disease control and symptom alleviation. The findings also provide insights for understanding stem cell pluripotency and raise a tantalizing possibility for using phytoplasma as a tool to dissect the course of normal plant development and to modify plant morphogenesis by manipulating meristem fate.

  17. Live Imaging of Shoot Meristems on an Inverted Confocal Microscope Using an Objective Lens Inverter Attachment.

    Science.gov (United States)

    Nimchuk, Zachary L; Perdue, Tony D

    2017-01-01

    Live imaging of above ground meristems can lead to new insights in plant development not possible from static imaging of fixed tissue. The use of an upright confocal microscope offers several technical and biological advantages for live imaging floral or shoot meristems. However, many departments and core facilities possess only inverted confocal microscopes and lack the funding for an additional upright confocal microscope. Here we show that imaging of living apical meristems can be performed on existing inverted confocal microscopes with the use of an affordable and detachable InverterScope accessory.

  18. Embryonic development in Arabidopsis thaliana: from the zygote division to the shoot meristem

    Directory of Open Access Journals (Sweden)

    Sonia eBoscá

    2011-12-01

    Full Text Available Postembryonic organ formation of plants is fueled with cells from the stem cell niches in the shoot and root meristems. During the last two decades considerable progress has been made in identifying factors that regulate stem cell maintenance. With these factors in hand, the mechanisms establishing stem cell niches during embryo development can be addressed. Here we discuss current models of how the shoot meristem stem cell niche arises during embryonic pattern formation.

  19. Regulation of floral meristem activity through the interaction of AGAMOUS, SUPERMAN, and CLAVATA3 in Arabidopsis.

    Science.gov (United States)

    Uemura, Akira; Yamaguchi, Nobutoshi; Xu, Yifeng; Wee, WanYi; Ichihashi, Yasunori; Suzuki, Takamasa; Shibata, Arisa; Shirasu, Ken; Ito, Toshiro

    2017-12-07

    Floral meristem size is redundantly controlled by CLAVATA3, AGAMOUS , and SUPERMAN in Arabidopsis. The proper regulation of floral meristem activity is key to the formation of optimally sized flowers with a fixed number of organs. In Arabidopsis thaliana, multiple regulators determine this activity. A small secreted peptide, CLAVATA3 (CLV3), functions as an important negative regulator of stem cell activity. Two transcription factors, AGAMOUS (AG) and SUPERMAN (SUP), act in different pathways to regulate the termination of floral meristem activity. Previous research has not addressed the genetic interactions among these three genes. Here, we quantified the floral developmental stage-specific phenotypic consequences of combining mutations of AG, SUP, and CLV3. Our detailed phenotypic and genetic analyses revealed that these three genes act in partially redundant pathways to coordinately modulate floral meristem sizes in a spatial and temporal manner. Analyses of the ag sup clv3 triple mutant, which developed a mass of undifferentiated cells in its flowers, allowed us to identify downstream targets of AG with roles in reproductive development and in the termination of floral meristem activity. Our study highlights the role of AG in repressing genes that are expressed in organ initial cells to control floral meristem activity.

  20. An activated form of UFO alters leaf development and produces ectopic floral and inflorescence meristems.

    Directory of Open Access Journals (Sweden)

    Eddy Risseeuw

    Full Text Available Plants are unique in their ability to continuously produce new meristems and organ primordia. In Arabidopsis, the transcription factor LEAFY (LFY functions as a master regulator of a gene network that is important for floral meristem and organ specification. UNUSUAL FLORAL ORGANS (UFO is a co-activator of LEAFY and is required for proper activation of APETALA3 in the floral meristem during the specification of stamens and petals. The ufo mutants display defects in other parts of the flower and the inflorescence, suggestive of additional roles. Here we show that the normal determinacy of the developing Arabidopsis leaves is affected by the expression of a gain-of-function UFO fusion protein with the VP16 transcriptional activator domain. In these lines, the rosette and cauline leaf primordia exhibit reiterated serration, and upon flowering produce ectopic meristems that develop into flowers, bract leaves and inflorescences. These striking phenotypes reveal that developing leaves maintain the competency to initiate flower and inflorescence programs. Furthermore, the gain-of-function phenotypes are dependent on LFY and the SEPALLATA (SEP MADS-box transcription factors, indicative of their functional interactions with UFO. The findings of this study also suggest that UFO promotes the establishment of the lateral meristems and primordia in the peripheral zone of the apical and floral meristems by enhancing the activity of LFY. These novel phenotypes along with the mutant phenotypes of UFO orthologs in other plant species suggest a broader function for UFO in plants.

  1. An activated form of UFO alters leaf development and produces ectopic floral and inflorescence meristems.

    Science.gov (United States)

    Risseeuw, Eddy; Venglat, Prakash; Xiang, Daoquan; Komendant, Kristina; Daskalchuk, Tim; Babic, Vivijan; Crosby, William; Datla, Raju

    2013-01-01

    Plants are unique in their ability to continuously produce new meristems and organ primordia. In Arabidopsis, the transcription factor LEAFY (LFY) functions as a master regulator of a gene network that is important for floral meristem and organ specification. UNUSUAL FLORAL ORGANS (UFO) is a co-activator of LEAFY and is required for proper activation of APETALA3 in the floral meristem during the specification of stamens and petals. The ufo mutants display defects in other parts of the flower and the inflorescence, suggestive of additional roles. Here we show that the normal determinacy of the developing Arabidopsis leaves is affected by the expression of a gain-of-function UFO fusion protein with the VP16 transcriptional activator domain. In these lines, the rosette and cauline leaf primordia exhibit reiterated serration, and upon flowering produce ectopic meristems that develop into flowers, bract leaves and inflorescences. These striking phenotypes reveal that developing leaves maintain the competency to initiate flower and inflorescence programs. Furthermore, the gain-of-function phenotypes are dependent on LFY and the SEPALLATA (SEP) MADS-box transcription factors, indicative of their functional interactions with UFO. The findings of this study also suggest that UFO promotes the establishment of the lateral meristems and primordia in the peripheral zone of the apical and floral meristems by enhancing the activity of LFY. These novel phenotypes along with the mutant phenotypes of UFO orthologs in other plant species suggest a broader function for UFO in plants.

  2. Induced mutations in ornamental plants by 'in vitro' irradiation of Petunia hybrida meristems

    International Nuclear Information System (INIS)

    Gonzalez-Jimenez, J.

    1993-01-01

    In recent decades it has been observed that for the induction of mutation in ornamental plants we can obtain better results when the plants are irradiated in vegetative state and even better 'in vitro' that when its are irradiated 'in vivo'. In this work the possibilities are showed to avoid the best use of a new biotechnology: the gamma irradiations on the meristem 'in vitro'. A tissue culture method was described for the best vegetative propagation of Petunia hybrid hort through morphogenesis induction of meristem. These were planted in the Murashige and Skoog's basic medium added with BAP and ANA. The pH was adjusted to 6.5 prior autoclaving at 121 Centigrade degree and 1.1 Kg/ cm 2 for 15 minutes. Latter the meristem of plantules in immature and mature physiology stated were irradiated with gamma ray doses ranging from 1.0 at 10.0 Gy. The meristem were then subcultived aseptically with the following results: 1) The immature stage was higher radio sensibilities. 2) The LD 50 for the matured plants was to ranged from 1.0 at 9.0 Gy. and immature 1.0 at 8.0 Gy. 3) The better doses was at 7.5 Gy. 4) The meristem gamma irradiation at 7.5 Gy. showed in the first culture: the adventitious bud induced and the multi meristem formation. 5) In the second cultured the results reveals the 'variegadas' plants formations and the new purples flowers. (Author)

  3. Transcript profiling of a novel plant meristem, the monocot cambium.

    Science.gov (United States)

    Zinkgraf, Matthew; Gerttula, Suzanne; Groover, Andrew

    2017-06-01

    While monocots lack the ability to produce a vascular cambium or woody growth, some monocot lineages evolved a novel lateral meristem, the monocot cambium, which supports secondary radial growth of stems. In contrast to the vascular cambium found in woody angiosperm and gymnosperm species, the monocot cambium produces secondary vascular bundles, which have an amphivasal organization of tracheids encircling a central strand of phloem. Currently there is no information concerning the molecular genetic basis of the development or evolution of the monocot cambium. Here we report high-quality transcriptomes for monocot cambium and early derivative tissues in two monocot genera, Yucca and Cordyline. Monocot cambium transcript profiles were compared to those of vascular cambia and secondary xylem tissues of two forest tree species, Populus trichocarpa and Eucalyptus grandis. Monocot cambium transcript levels showed that there are extensive overlaps between the regulation of monocot cambia and vascular cambia. Candidate regulatory genes that vary between the monocot and vascular cambia were also identified, and included members of the KANADI and CLE families involved in polarity and cell-cell signaling, respectively. We suggest that the monocot cambium may have evolved in part through reactivation of genetic mechanisms involved in vascular cambium regulation. Published 2017. This article is a U.S. Government work and is in the public domain in the USA.

  4. Cryopreservation of Lilium martagon l. meristems by droplet-vitrification and evaluation of their physiological stability.

    Science.gov (United States)

    Urbaniec-Kiepura, M; Bach, A

    The aim of the present study was to compare different strategies for cryopreservation of martagon lily meristems and to evaluate the physiological status of the regenerants. The bulblets were stored at 5 degree C or 20 degree C and pretreated with 3% or 6% sucrose prior to droplet-vitrification. The meristems were then assessed for their survival and regeneration. Their photochemical activity was investigated using a Photosynthesis Yield Analyzer MINI PAM 2000 Portable Chlorophyll Fluorometer and their photosynthesis oxygen production was evaluated with a Plant Vital 5030 device. The plant material stored at 5 degree C on medium containing 3% sucrose exhibited lower survival (40.8%) and regeneration (75%) of meristems following cryopreservation compared with material stored at 20 degree C on medium containing 3% sucrose, for which survival was 65% and regeneration 87%. Treatment of lily meristems for 30 min with PVS2 yielded high survival and regeneration. The implemented cryopreservation protocol did not induce any physiological changes in regenerants. Chlorophyll fluorescence (Fv/Fm) was 0.822 for cryopreserved samples (+LN) and 0.824 for non-cryopreserved ones (-LN). Photosynthetic oxygen production (KphA) was 1.531 (+LN) and 1.410 (-LN). Droplet-vitrification seems to be an effective method for cryopreservation of martagon lily meristems with the aim of its ex situ protection.

  5. Meristem micropropagation of cassava (Manihot esculenta) evokes genome-wide changes in DNA methylation.

    Science.gov (United States)

    Kitimu, Shedrack R; Taylor, Julian; March, Timothy J; Tairo, Fred; Wilkinson, Mike J; Rodríguez López, Carlos M

    2015-01-01

    There is great interest in the phenotypic, genetic and epigenetic changes associated with plant in vitro culture known as somaclonal variation. In vitro propagation systems that are based on the use of microcuttings or meristem cultures are considered analogous to clonal cuttings and so widely viewed to be largely free from such somaclonal effects. In this study, we surveyed for epigenetic changes during propagation by meristem culture and by field cuttings in five cassava (Manihot esculenta) cultivars. Principal Co-ordinate Analysis of profiles generated by methylation-sensitive amplified polymorphism revealed clear divergence between samples taken from field-grown cuttings and those recovered from meristem culture. There was also good separation between the tissues of field samples but this effect was less distinct among the meristem culture materials. Application of methylation-sensitive Genotype by sequencing identified 105 candidate epimarks that distinguish between field cutting and meristem culture samples. Cross referencing the sequences of these epimarks to the draft cassava genome revealed 102 sites associated with genes whose homologs have been implicated in a range of fundamental biological processes including cell differentiation, development, sugar metabolism, DNA methylation, stress response, photosynthesis, and transposon activation. We explore the relevance of these findings for the selection of micropropagation systems for use on this and other crops.

  6. Brassinosteroids Modulate Meristem Fate and Differentiation of Unique Inflorescence Morphology in Setaria viridis[OPEN

    Science.gov (United States)

    Thames, Shuiyi; Jiang, Hui

    2018-01-01

    Inflorescence architecture is a key determinant of yield potential in many crops and is patterned by the organization and developmental fate of axillary meristems. In cereals, flowers and grain are borne from spikelets, which differentiate in the final iteration of axillary meristem branching. In Setaria spp, inflorescence branches terminate in either a spikelet or a sterile bristle, and these structures appear to be paired. In this work, we leverage Setaria viridis to investigate a role for the phytohormones brassinosteroids (BRs) in specifying bristle identity and maintaining spikelet meristem determinacy. We report the molecular identification and characterization of the Bristleless1 (Bsl1) locus in S. viridis, which encodes a rate-limiting enzyme in BR biosynthesis. Loss-of-function bsl1 mutants fail to initiate a bristle identity program, resulting in homeotic conversion of bristles to spikelets. In addition, spikelet meristem determinacy is altered in the mutants, which produce two florets per spikelet instead of one. Both of these phenotypes provide avenues for enhanced grain production in cereal crops. Our results indicate that the spatiotemporal restriction of BR biosynthesis at boundary domains influences meristem fate decisions during inflorescence development. The bsl1 mutants provide insight into the molecular basis underlying morphological variation in inflorescence architecture. PMID:29263085

  7. Effects of apical meristem loss on sylleptic branching and growth of hybrid poplar

    Energy Technology Data Exchange (ETDEWEB)

    Zeleznik, Joseph D. [North Dakota State University, Fargo, ND (United States). Plant Sciences Department

    2007-07-15

    The effects of apical meristem loss on the growth and development of hybrid poplar trees was investigated. This was done by clipping back either the apical meristem alone (dividing cells), or the apical meristem plus a small amount of additional stem tissue (expanding cells, <1 cm), at various times during the first growing season. Two clones (NM6-nonsylleptic habit, and DN34-slightly sylleptic habit) were tested at close spacing (0.6 m) in the nursery. Clipping generally increased the number of sylleptic branches formed. Clipping 69 days after planting resulted in the largest number of sylleptic branches while clipping 4 weeks later gave no increase in syllepsis. Clipping temporarily reduced height growth of both clones but total height at the end of the first growing season was not affected by any treatment. There were some slight differences in growth during the second growing season; despite these differences, total stem biomass and total tree biomass after 2 years were not affected by temporary loss of the apical meristem in the first growing season. Results suggest that death or removal of hybrid poplar apical meristems by tip borers or ungulates has no long-term effects on aboveground growth as measured by height or biomass. (author)

  8. Comparative evaluation of total RNA extraction methods in Theobroma cacao using shoot apical meristems.

    Science.gov (United States)

    Silva, D V; Branco, S M J; Holanda, I S A; Royaert, S; Motamayor, J C; Marelli, J P; Corrêa, R X

    2016-03-04

    Theobroma cacao is a species of great economic importance with its beans used for chocolate production. The tree has been a target of various molecular studies. It contains many polyphenols, which complicate the extraction of nucleic acids with the extraction protocols requiring a large amount of plant material. These issues, therefore, necessitate the optimization of the protocols. The aim of the present study was to evaluate different methods for extraction of total RNA from shoot apical meristems of T. cacao 'CCN 51' and to assess the influence of storage conditions for the meristems on the extraction. The study also aimed to identify the most efficient protocol for RNA extraction using a small amount of plant material. Four different protocols were evaluated for RNA extraction using one shoot apical meristem per sample. Among these protocols, one that was more efficient was then tested to extract RNA using four different numbers of shoot apical meristems, subjected to three different storage conditions. The best protocol was tested for cDNA amplification using reverse transcription-polymerase chain reaction; the cDNA quality was determined to be satisfactory for molecular analyses. The study revealed that with the best RNA extraction protocol, one shoot apical meristem was sufficient for extraction of high-quality total RNA. The results obtained might enable advances in genetic analyses and molecular studies using reduced amount of plant material.

  9. Live imaging of developmental processes in a living meristem of Davidia involucrata (Nyssaceae

    Directory of Open Access Journals (Sweden)

    Markus eJerominek

    2014-11-01

    Full Text Available Morphogenesis in plants is usually reconstructed by scanning electron microscopy and histology of meristematic structures. These techniques are destructive and require many samples to obtain a consecutive series of states. Unfortunately, using this methodology the absolute timing of growth and complete relative initiation of organs remain obscure. To overcome this limitation, an in vivo observational method based on Epi-Illumination Light Microscopy (ELM was developed and tested with a male inflorescence meristem (floral unit of the handkerchief tree Davidia involucrata Baill. (Nyssaceae. We asked whether the most basal flowers of this floral unit arise in a basipetal sequence or, alternatively, are delayed in their development.The growing meristem was observed for 30 days, the longest live observation of a meristem achieved to date. The sequence of primordium initiation indicates a later initiation of the most basal flowers and not earlier or simultaneously as SEM images could suggest. D. involucrata exemplarily shows that live-ELM gives new insights into developmental processes of plants. In addition to morphogenetic questions such as the transition from vegetative to reproductive meristems or the absolute timing of ontogenetic processes, this method may also help to quantify cellular growth processes in the context of molecular physiology and developmental genetics studies.

  10. Effect of 6-benzyl aminopurine (BAP) on meristem culture for virus ...

    African Journals Online (AJOL)

    , Granula and Cardinal for meristem culture and four 6-benzyl aminopurine levels namely 0, 1.0, 1.5, 2.0 mg/l. As a whole, twenty treatments were allotted in complete randomized design with three replications. Resulted in vitro regenerated ...

  11. (BAP) on meristem culture for virus free seed production of some ...

    African Journals Online (AJOL)

    Hiru

    2013-05-01

    May 1, 2013 ... tubers for ware potato production: Influence of size and plant spacing. Asian Potato J. 3:14-17. Sanavy SAMM, Moieni MJ (2003). Effects of different hormone combinations and planting beds on growth of single nodes and plantlets resulted from potato meristem culture. Plant Tissue Cult. 13(2):145-150.

  12. The bZIP transcription factor PERIANTHIA: A multifunctional hub for meristem control

    Directory of Open Access Journals (Sweden)

    Jan eLohmann

    2011-11-01

    Full Text Available As sessile organisms, plants are exposed to extreme variations in environmental conditions over the course of their lives. Since plants grow and initiate new organs continuously, they have to modulate the underlying developmental program accordingly to cope with this challenge. At the heart of this extraordinary developmental plasticity are pluripotent stem cells, which are maintained during the entire life-cycle of the plant and that are embedded within dynamic stem cell niches. While the complex regulatory principles of plant stem cell control under artificial constant growth conditions begin to emerge, virtually nothing is known about how this circuit adapts to variations in the environment. In addition to the local feedback system constituted by the homeodomain transcription factor WUSCHEL (WUS and the CLAVATA signaling cascade in the center of the shoot apical meristem (SAM, the bZIP transcription factor PERIANTHIA (PAN not only has a broader expression domain in SAM and flowers, but also carries out more diverse functions in meristem maintenance: pan mutants show alterations in environmental response, shoot meristem size, floral organ number and exhibit severe defects in termination of floral stem cells in an environment dependent fashion. Genetic and genomic analyses indicate that PAN interacts with a plethora of developmental pathways including light, plant hormone and meristem control systems, suggesting that PAN is as an important regulatory node in the network of plant stem cell control.

  13. Requirement of B2-Type Cyclin-Dependent Kinases for Meristem Integrity in Arabidopsis thaliana

    Czech Academy of Sciences Publication Activity Database

    Andersen, S.U.; Buechel, S.; Zhao, Z.; Ljung, K.; Novák, Ondřej; Busch, W.; Schuster, Ch.; Lohmann, J.U.

    2008-01-01

    Roč. 20, č. 1 (2008), s. 88-100 ISSN 1040-4651 Institutional research plan: CEZ:AV0Z50380511 Keywords : SHOOT APICAL MERISTEM * CELL-CYCLE * PLANT DEVELOPMENT Subject RIV: CE - Biochemistry Impact factor: 9.296, year: 2008

  14. CYCP2;1 integrates genetic and nutritional information to promote meristem cell division in Arabidopsis

    Czech Academy of Sciences Publication Activity Database

    Peng, L.; Skylar, A.; Chang, P.L.; Bišová, Kateřina; Wu, X.

    2014-01-01

    Roč. 393, č. 2 (2014), s. 160-170 ISSN 0012-1606 R&D Projects: GA AV ČR M200201205 Grant - others:NSF(US) MCB-1122213 Institutional support: RVO:61388971 Keywords : cell cycle * arabidopsis * meristem Subject RIV: EE - Microbiology, Virology Impact factor: 3.547, year: 2014

  15. Spatial coordination between stem cell activity and cell differentiation in the root meristem

    NARCIS (Netherlands)

    Moubayidin, L.; Mambro, Di R.; Sozzani, R.; Pacifici, E.; Salvi, E.; Terpstra, I.; Bao, D.; Dijken, van A.; Dello loio, R.; Perilli, S.; Ljung, K.; Benfey, P.N.; Heidstra, R.; Costantino, P.; Sabatini, S.

    2013-01-01

    A critical issue in development is the coordination of the activity of stem cell niches with differentiation of their progeny to ensure coherent organ growth. In the plant root, these processes take place at opposite ends of the meristem and must be coordinated with each other at a distance. Here,

  16. UFO in the Arabidopsis inflorescence apex is required for floral-meristem identity and bract suppression.

    Science.gov (United States)

    Hepworth, Shelley R; Klenz, Jennifer E; Haughn, George W

    2006-03-01

    The UNUSUAL FLORAL ORGANS (UFO) gene of Arabidopsis encodes an F-box protein required for the determination of floral-organ and floral-meristem identity. Mutation of UFO leads to dramatic changes in floral-organ type which are well-characterized whereas inflorescence defects are more subtle and less understood. These defects include an increase in the number of secondary inflorescences, nodes that alternate between forming flowers and secondary inflorescences, and nodes in which a single flower is subtended by a bract. Here, we show how inflorescence defects correlate with the abnormal development of floral primordia and establish a temporal requirement for UFO in this process. At the inflorescence apex of ufo mutants, newly formed primordia are initially bract-like. Expression of the floral-meristem identity genes LFY and AP1 are confined to a relatively small adaxial region of these primordia with expression of the bract-identity marker FIL observed in cells that comprise the balance of the primordia. Proliferation of cells in the adaxial region of these early primordia is delayed by several nodes such that primordia appear "chimeric" at several nodes, having visible floral and bract components. However, by late stage 2 of floral development, growth of the bract generally ceases and is overtaken by development of the floral primordium. This abnormal pattern of floral meristem development is not rescued by expression of UFO from the AP1 promoter, indicating that UFO is required prior to AP1 activation for normal development of floral primordia. We propose that UFO and LFY are jointly required in the inflorescence meristem to both promote floral meristem development and inhibit, in a non-cell autonomous manner, growth of the bract.

  17. FON2 SPARE1 Redundantly Regulates Floral Meristem Maintenance with FLORAL ORGAN NUMBER2 in Rice

    Science.gov (United States)

    Suzaki, Takuya; Ohneda, Masako; Toriba, Taiyo; Yoshida, Akiko; Hirano, Hiro-Yuki

    2009-01-01

    CLAVATA signaling restricts stem cell identity in the shoot apical meristem (SAM) in Arabidopsis thaliana. In rice (Oryza sativa), FLORAL ORGAN NUMBER2 (FON2), closely related to CLV3, is involved as a signaling molecule in a similar pathway to negatively regulate stem cell proliferation in the floral meristem (FM). Here we show that the FON2 SPARE1 (FOS1) gene encoding a CLE protein functions along with FON2 in maintenance of the FM. In addition, FOS1 appears to be involved in maintenance of the SAM in the vegetative phase, because constitutive expression of FOS1 caused termination of the vegetative SAM. Genetic analysis revealed that FOS1 does not need FON1, the putative receptor of FON2, for its action, suggesting that FOS1 and FON2 may function in meristem maintenance as signaling molecules in independent pathways. Initially, we identified FOS1 as a suppressor that originates from O. sativa indica and suppresses the fon2 mutation in O. sativa japonica. FOS1 function in japonica appears to be compromised by a functional nucleotide polymorphism (FNP) at the putative processing site of the signal peptide. Sequence comparison of FOS1 in about 150 domesticated rice and wild rice species indicates that this FNP is present only in japonica, suggesting that redundant regulation by FOS1 and FON2 is commonplace in species in the Oryza genus. Distribution of the FNP also suggests that this mutation may have occurred during the divergence of japonica from its wild ancestor. Stem cell maintenance may be regulated by at least three negative pathways in rice, and each pathway may contribute differently to this regulation depending on the type of the meristem. This situation contrasts with that in Arabidopsis, where CLV signaling is the major single pathway in all meristems. PMID:19834537

  18. FON2 SPARE1 redundantly regulates floral meristem maintenance with FLORAL ORGAN NUMBER2 in rice.

    Directory of Open Access Journals (Sweden)

    Takuya Suzaki

    2009-10-01

    Full Text Available CLAVATA signaling restricts stem cell identity in the shoot apical meristem (SAM in Arabidopsis thaliana. In rice (Oryza sativa, FLORAL ORGAN NUMBER2 (FON2, closely related to CLV3, is involved as a signaling molecule in a similar pathway to negatively regulate stem cell proliferation in the floral meristem (FM. Here we show that the FON2 SPARE1 (FOS1 gene encoding a CLE protein functions along with FON2 in maintenance of the FM. In addition, FOS1 appears to be involved in maintenance of the SAM in the vegetative phase, because constitutive expression of FOS1 caused termination of the vegetative SAM. Genetic analysis revealed that FOS1 does not need FON1, the putative receptor of FON2, for its action, suggesting that FOS1 and FON2 may function in meristem maintenance as signaling molecules in independent pathways. Initially, we identified FOS1 as a suppressor that originates from O. sativa indica and suppresses the fon2 mutation in O. sativa japonica. FOS1 function in japonica appears to be compromised by a functional nucleotide polymorphism (FNP at the putative processing site of the signal peptide. Sequence comparison of FOS1 in about 150 domesticated rice and wild rice species indicates that this FNP is present only in japonica, suggesting that redundant regulation by FOS1 and FON2 is commonplace in species in the Oryza genus. Distribution of the FNP also suggests that this mutation may have occurred during the divergence of japonica from its wild ancestor. Stem cell maintenance may be regulated by at least three negative pathways in rice, and each pathway may contribute differently to this regulation depending on the type of the meristem. This situation contrasts with that in Arabidopsis, where CLV signaling is the major single pathway in all meristems.

  19. WUS and STM-based reporter genes for studying meristem development in poplar.

    Science.gov (United States)

    Bao, Y; Dharmawardhana, P; Arias, R; Allen, M B; Ma, C; Strauss, Steven H

    2009-06-01

    We describe the development of a reporter system for monitoring meristem initiation in poplar using promoters of poplar homologs to the meristem-active regulatory genes WUSCHEL (WUS) and SHOOTMERISTEMLESS (STM). When ~3 kb of the 5' flanking regions of close homologs were used to drive expression of the GUSPlus gene, 50-60% of the transgenic events showed expression in apical and axillary meristems. However, expression was also common in other organs, including in leaf veins (40 and 46% of WUS and STM transgenic events, respectively) and hydathodes (56% of WUS transgenic events). Histochemical GUS staining of explants during callogenesis and shoot regeneration using in vitro stems as explants showed that expression was detectable prior to visible shoot development, starting 3-15 days after explants were placed onto callus inducing medium. A minority of WUS and STM events also showed expression in the cambium, phloem, or xylem of regenerated, greenhouse grown plants undergoing secondary growth. Based on microarray gene expression data, a paralog of poplar WUS was detectably up-regulated during shoot initiation, but the other paralog was not. Both paralogs of poplar STM were down-regulated threefold to sixfold during early callus initiation. We identified 15-35 copies of cytokinin response regulator binding motifs (ARR1AT) and one copy of the auxin response element (AuxRE) in both promoters. Several of the events recovered may be useful for studying the process of primary and secondary meristem development, including treatments intended to stimulate meristem development to promote clonal propagation and genetic transformation.

  20. Meristem culture and subsequent micropropagation of Chilean strawberry (Fragaria chiloensis (L. Duch.

    Directory of Open Access Journals (Sweden)

    Karla A. Quiroz

    Full Text Available Abstract Background: Vegetative propagation of Fragaria sp. is traditionally carried out using stolons. This system of propagation, in addition to being slow, can spread plant diseases, particularly serious being viral. In vitro culture of meristems and the establishment of micropropagation protocols are important tools for solving these problems. In recent years, considerable effort has been made to develop in vitro propagation of the commercial strawberry in order to produce virus-free plants of high quality. These previous results can serve as the basis for developing in vitro-based propagation technologies in the less studied species Fragaria chiloensis. Results: In this context, we studied the cultivation of meristems and establishment of a micropropagation protocol for F. chiloensis. The addition of polyvinylpyrrolidone (PVP improved the meristem regeneration efficiency of F. chiloensis accessions. Similarly, the use of 6-benzylaminopurine (BAP in the culture media increased the average rate of multiplication to 3-6 shoots per plant. In addition, the use of 6-benzylaminopurine (BAP, had low levels (near zero of explant losses due to oxidation. However, plant height as well as number of leaves and roots were higher in media without growth regulators, with average values of 0.5 cm, 9 leaves and 4 roots per plant. Conclusions: For the first time in Chilean strawberry, meristem culture demonstrated to be an efficient tool for eliminating virus from infected plants, giving the possibility to produce disease free propagation material. Also, the addition of PVP into the basal MS medium improved the efficiency of plant recovery from isolated meristems. Farmers can now access to high quality plant material produced by biotech tools which will improve their technological practices.

  1. Meristem culture and subsequent micropropagation of Chilean strawberry (Fragaria chiloensis (L.) Duch.).

    Science.gov (United States)

    Quiroz, Karla A; Berríos, Miguel; Carrasco, Basilio; Retamales, Jorge B; Caligari, Peter D S; García-Gonzáles, Rolando

    2017-06-02

    Vegetative propagation of Fragaria sp. is traditionally carried out using stolons. This system of propagation, in addition to being slow, can spread plant diseases, particularly serious being viral. In vitro culture of meristems and the establishment of micropropagation protocols are important tools for solving these problems. In recent years, considerable effort has been made to develop in vitro propagation of the commercial strawberry in order to produce virus-free plants of high quality. These previous results can serve as the basis for developing in vitro-based propagation technologies in the less studied species Fragaria chiloensis. In this context, we studied the cultivation of meristems and establishment of a micropropagation protocol for F. chiloensis. The addition of polyvinylpyrrolidone (PVP) improved the meristem regeneration efficiency of F. chiloensis accessions. Similarly, the use of 6-benzylaminopurine (BAP) in the culture media increased the average rate of multiplication to 3-6 shoots per plant. In addition, the use of 6-benzylaminopurine (BAP), had low levels (near zero) of explant losses due to oxidation. However, plant height as well as number of leaves and roots were higher in media without growth regulators, with average values of 0.5 cm, 9 leaves and 4 roots per plant. For the first time in Chilean strawberry, meristem culture demonstrated to be an efficient tool for eliminating virus from infected plants, giving the possibility to produce disease free propagation material. Also, the addition of PVP into the basal MS medium improved the efficiency of plant recovery from isolated meristems. Farmers can now access to high quality plant material produced by biotech tools which will improve their technological practices.

  2. The natural compound benzoxazolin-2(3H)-one selectively retards cell cycle in lettuce root meristems.

    Science.gov (United States)

    Sánchez-Moreiras, Adela M; de la Peña, Teodoro Coba; Reigosa, Manuel J

    2008-08-01

    Benzoxazolin-2(3H)-one (BOA) is a natural plant product that is phytotoxic to target plant species, inhibiting germination and growth and causing oxidative damage. We investigated its effects on the root meristems of seedlings of lettuce (Lactuca sativa) by means of light and transmission electron microscopy, flow cytometry, and conventional determination of mitotic index. Flow cytometry analyses and mitotic index showed a retard of cell cycle in BOA-treated meristems with selective activity at G2/M checkpoint.

  3. UFO: an Arabidopsis gene involved in both floral meristem and floral organ development.

    Science.gov (United States)

    Levin, J Z; Meyerowitz, E M

    1995-05-01

    We describe the role of the UNUSUAL FLORAL ORGANS (UFO) gene in Arabidopsis floral development based on a genetic and molecular characterization of the phenotypes of nine ufo alleles. UFO is required for the proper identity of the floral meristem and acts in three different aspects of the process that distinguishes flowers from shoots. UFO is involved in establishing the whorled pattern of floral organs, controlling the determinacy of the floral meristem, and activating the APETALA3 and PISTILLATA genes required for petal and stamen identity. In many respects, UFO acts in a manner similar to LEAFY, but the ufo mutant phenotype also suggests an additional role for UFO in defining boundaries within the floral primordia or controlling cell proliferation during floral organ growth. Finally, genetic interactions that prevent flower formation and lead to the generation of filamentous structures implicate UFO as a member of a new, large, and diverse class of genes in Arabidopsis necessary for flower formation.

  4. Improved and Reproducible Flow Cytometry Methodology for Nuclei Isolation from Single Root Meristem

    Directory of Open Access Journals (Sweden)

    Thaís Cristina Ribeiro Silva

    2010-01-01

    Full Text Available Root meristems have increasingly been target of cell cycle studies by flow cytometric DNA content quantification. Moreover, roots can be an alternative source of nuclear suspension when leaves become unfeasible and for chromosome analysis and sorting. In the present paper, a protocol for intact nuclei isolation from a single root meristem was developed. This proceeding was based on excision of the meristematic region using a prototypical slide, followed by short enzymatic digestion and mechanical isolation of nuclei during homogenization with a hand mixer. Such parameters were optimized for reaching better results. Satisfactory nuclei amounts were extracted and analyzed by flow cytometry, producing histograms with reduced background noise and CVs between 3.2 and 4.1%. This improved and reproducible technique was shown to be rapid, inexpensive, and simple for nuclear extraction from a single root tip, and can be adapted for other plants and purposes.

  5. Mechanically, the shoot apical meristem of Arabidopsis behaves like a shell inflated by a pressure of about 1 MPa

    Directory of Open Access Journals (Sweden)

    Léna eBeauzamy

    2015-11-01

    Full Text Available In plants, the shoot apical meristem contains the stem cells and is responsible for the generation of all aerial organs. Mechanistically, organogenesis is associated with an auxin-dependent local softening of the epidermis. This has been proposed to be sufficient to trigger outgrowth, because the epidermis is thought to be under tension and stiffer than internal tissues in all the aerial part of the plant. However, this has not been directly demonstrated in the shoot apical meristem. Here we tested this hypothesis in Arabidopsis using indentation methods and modeling. We considered two possible scenarios: either the epidermis does not have unique properties and the meristem behaves as a homogeneous linearly-elastic tissue, or the epidermis is under tension and the meristem exhibits the response of a shell under pressure. Large indentation depths measurements with a large tip (~size of the meristem were consistent with a shell-like behavior. This also allowed us to deduce a value of turgor pressure, estimated at 0.82 ± 0.16 MPa. Indentation with atomic force microscopy provided local measurements of pressure in the epidermis, further confirming the values obtained from large deformations. Altogether, our data demonstrate that the Arabidopsis shoot apical meristem behaves like a shell under a MPa range pressure and support a key role for the epidermis in shaping the shoot apex.

  6. Autoradiographic study of gamma-ray induced unscheduled DNA synthesis in bean root meristem cells

    International Nuclear Information System (INIS)

    Liu Zhenshen; Qiu Quanfa; Chen Dongli

    1989-01-01

    The gamma-ray induced unscheduled DNA synthesis in root meristem cells of Vica faba was studied autoradiographically by calculating the number of cells with different 3H-thymidine labelling degree. It was found that the level of unscheduled synthesis in cells with intermediate dose (500 R) irradiation was higher than that in cells with lower dose (250 R) irradiation; however, higher dose (1000 R) irradiation would inhibit the reparative replication

  7. Impairment of Meristem Proliferation in Plants Lacking the Mitochondrial Protease AtFTSH4

    Directory of Open Access Journals (Sweden)

    Alicja Dolzblasz

    2018-03-01

    Full Text Available Shoot and root apical meristems (SAM and RAM, respectively are crucial to provide cells for growth and organogenesis and therefore need to be maintained throughout the life of a plant. However, plants lacking the mitochondrial protease AtFTSH4 exhibit an intriguing phenotype of precocious cessation of growth at both the shoot and root apices when grown at elevated temperatures. This is due to the accumulation of internal oxidative stress and progressive mitochondria dysfunction. To explore the impacts of the internal oxidative stress on SAM and RAM functioning, we study the expression of selected meristem-specific (STM, CLV3, WOX5 and cell cycle-related (e.g., CYCB1, CYCD3;1 genes at the level of the promoter activity and/or transcript abundance in wild-type and loss-of-function ftsh4-1 mutant plants grown at 30 °C. In addition, we monitor cell cycle progression directly in apical meristems and analyze the responsiveness of SAM and RAM to plant hormones. We show that growth arrest in the ftsh4-1 mutant is caused by cell cycle dysregulation in addition to the loss of stem cell identity. Both the SAM and RAM gradually lose their proliferative activity, but with different timing relative to CYCB1 transcriptional activity (a marker of G2-M transition, which cannot be compensated by exogenous hormones.

  8. Regeneration of three sweet potato (Ipomea batatas (L.)) accessions via meristem, Nodal and callus induction

    International Nuclear Information System (INIS)

    Addae-Frimpomaah, F.

    2012-11-01

    In vitro regeneration of three sweet potato accessions UE007, UK-BNARI and SA-BNARI using meristem, nodal cuttings or callus induction was studied. Meristematic explants cultured on Murashige and Skoog (1962) basal medium supplemented with low concentration of benzylaminopurine (BAP) or kinetin resulted in callus with or without shoot development which delayed shoot emergence. The degree of callus development increased as the concentration of the cytokinin in the culture medium increased. Although, callus development was comparatively lower on kinetin amended medium than BAP amended medium, Murashige and Skoog medium supplemented with 0.25mg/1BAP had the highest shoot induction (80%). For further differentiation of callus or shoots into distinct stem and leaves, the culture were transferred into fresh MS medium supplemented with 0.25mg/1 BAP, 0.1 mg/1 NAA and 0.1 mg/1 Gibberellic acid (GA 3 . To overcome the delay in shoot initiation using meristem culture, nodal cuttings of sweet potato were used as explants and cultured on MS medium amended with 0.3 - 0.9mg/1 BAP. All explants cultured on 0.3 or 0.6mg/1 BAP developed shoots. Furthermore, liquid MS medium amended with 0.25mg/1 BAP, 0.1mg/I NAA, and 0.1mg/1 GA 3 also enhanced early shoot development from nodal cutting explants compared to solid culture. Post flask acclimatisation of meristem or nodal cutting-derived plantlets showed that meristem derived plantlets were better acclimatised than nodal cutting plants due to vigorous root development leading to higher percentage survival in pots and subsequent tuber production. Callusogenesis was achieved when leaf lobe explants were cultured on CLC/ Ipomoea medium supplemented with 1.0 - 4.0mg/1 2,4-D with 4.0mg/1 2,4-D being the optimal concentration. However, the calli were non-embryogenic and therefore could not produce embryos when transferred to 0.1mg/1 BAP amended medium but rather produced either single or multiple shoots. The highest percentage shoot (83

  9. Floral Meristem Identity Genes Are Expressed during Tendril Development in Grapevine1

    Science.gov (United States)

    Calonje, Myriam; Cubas, Pilar; Martínez-Zapater, José M.; Carmona, María José

    2004-01-01

    To study the early steps of flower initiation and development in grapevine (Vitis vinifera), we have isolated two MADS-box genes, VFUL-L and VAP1, the putative FUL-like and AP1 grapevine orthologs, and analyzed their expression patterns during vegetative and reproductive development. Both genes are expressed in lateral meristems that, in grapevine, can give rise to either inflorescences or tendrils. They are also coexpressed in inflorescence and flower meristems. During flower development, VFUL-L transcripts are restricted to the central part of young flower meristems and, later, to the prospective carpel-forming region, which is consistent with a role of this gene in floral transition and carpel and fruit development. Expression pattern of VAP1 suggests that it may play a role in flowering transition and flower development. However, its lack of expression in sepal primordia, does not support its role as an A-function gene in grapevine. Neither VFUL-L nor VAP1 expression was detected in vegetative organs such as leaves or roots. In contrast, they are expressed throughout tendril development. Transcription of both genes in tendrils of very young plants that have not undergone flowering transition indicates that this expression is independent of the flowering process. These unique expression patterns of genes typically involved in reproductive development have implications on our understanding of flower induction and initiation in grapevine, on the origin of grapevine tendrils and on the functional roles of AP1-and FUL-like genes in plant development. These results also provide molecular support to the hypothesis that Vitis tendrils are modified reproductive organs adapted to climb. PMID:15247405

  10. Ultrastructural changes associated with cryopreservation of banana ( Musa spp.) highly proliferating meristems.

    Science.gov (United States)

    Helliot, B; Swennen, R; Poumay, Y; Frison, E; Lepoivre, P; Panis, B

    2003-03-01

    Cryopreservation has been shown to improve the frequency of virus elimination - specifically cucumber mosaic virus and banana streak virus - from banana ( Musa spp.) plants. To understand the mode of action of cryopreservation for the eradication of viral particles, we examined the ultrastructure of meristem tips at each step of the cryopreservation process. Excised meristematic clumps produced from infected banana plants belonging to cv. Williams (AAA, Cavendish subgroup) were cryopreserved through vitrification using the PVS-2 solution. We demonstrated that the cryopreservation method used only allowed survival of small areas of cells in the meristematic dome and at the base of the primordia. Cellular and subcellular changes occurring during the cryopreservation process are discussed.

  11. Aphidicolin as synchronizing agent in root tip meristems of Haplopappus gracilis.

    Science.gov (United States)

    Galli, M G; Sala, F

    1983-06-01

    Aphidicolin, a reversible inhibitor of nuclear DNA replication, was tested as syncrhonizing agent in root tip meristems of Haplopappus gracilis. Embryos (i.e. decoated seeds) or 3-day-old seedlings were used to this purpose. After a 24 h treatment with the drug, a high level of synchrony was observed in both experimental materials for two cell cycles as assessed by determining the accumulation of cells in the S and M phases of the cycle. Highest synchronization was obtained with germinating embryos, possibly owing to a low degree of synchrony already existing in this system.

  12. Optimization of a protocol for direct organogenesis of red clover (Trifolium pratense L. meristems for breeding purposes

    Directory of Open Access Journals (Sweden)

    JUAN C CARRILLO

    2004-01-01

    Full Text Available A series of experiments were carried out in order to optimize a protocol for the direct organogenesis of Chilean red clover germplasm. A range of cultivars were used to analyze the effect of explant source (crown or stem meristems of vegetative plants, culture media and plant growth regulators. Our findings showed that stem meristems were easier to obtain, presented lower levels of contamination and a better development than crown meristems. The L2 medium showed better results than B5 and MS media for the cultivars and experimental lines studied. L2 medium supplemented with 0.003 mg/l of 4-amino-3,5,6-trichloropicolinic acid and 1.0 mg/l of 6-benzylaminopurine gave consistently better results and will be applied in our breeding program to propagate, maintain and eliminate viruses from elite red clover clones.

  13. Evolution of floral meristem identity genes. Analysis of Lolium temulentum genes related to APETALA1 and LEAFY of Arabidopsis

    DEFF Research Database (Denmark)

    Gocal, G.F.W.; King, R.W.; Blundell, C.A.

    2001-01-01

    Flowering (inflorescence formation) of the grass Lolium temulentum is strictly regulated, occurring rapidly on exposure to a single long day (LD). During floral induction, L. temulentum differs significantly from dicot species such as Arabidopsis in the expression, at the shoot apex, of two APETALA......1 (AP1)-like genes, LtMADS1 and LtMADS2, and of L. temulentum LEAFY (LtLFY). As shown by in situ hybridization, LtMADS1 and LtMADS2 are expressed in the vegetative shoot apical meristem, but expression increases strongly within 30 h of LD floral induction. Later in floral development, LtMADS1 and Lt......MADS2 are expressed within spikelet and floret meristems and in the glume and lemma primordia. It is interesting that LtLFY is detected quite late (about 12 d after LD induction) within the spikelet meristems, glumes, and lemma primordia. These patterns contrast with Arabidopsis, where LFY and AP1...

  14. Repression of Lateral Organ Boundary Genes by PENNYWISE and POUND-FOOLISH Is Essential for Meristem Maintenance and Flowering in Arabidopsis

    NARCIS (Netherlands)

    Khan, Madiha; Ragni, Laura; Tabb, Paul; Salasini, Brenda C; Chatfield, Steven; Datla, Raju; Lock, John; Kuai, Xiahezi; Després, Charles; Proveniers, Marcel; Yongguo, Cao; Xiang, Daoquan; Morin, Halima; Rullière, Jean-Pierre; Citerne, Sylvie; Hepworth, Shelley R; Pautot, Véronique

    2015-01-01

    In the model plant Arabidopsis (Arabidopsis thaliana), endogenous and environmental signals acting on the shoot apical meristem cause acquisition of inflorescence meristem fate. This results in changed patterns of aerial development seen as the transition from making leaves to the production of

  15. The dicerlike-1 homologue, fuzzy tassel, is required for the regulatin of meristem deteminancy in the inflorescence and vegetative growth in maize

    Science.gov (United States)

    Plant architecture is determined by meristems that initiate leaves during vegetative development and flowers during reproductive development. Maize (Zea mays) inflorescences are patterned by a series of branching events, culminating in floral meristems that produce sexual organs. The maize fuzzy tas...

  16. The CUP-SHAPED COTYLEDON3 gene is required for boundary and shoot meristem formation in Arabidopsis

    DEFF Research Database (Denmark)

    Vroemen, Casper W; Mordhorst, Andreas P; Albrecht, Cathy

    2003-01-01

    From an enhancer trap screen for genes expressed in Arabidopsis embryos, we identified a gene expressed from the octant stage onward in the boundary between the two presumptive cotyledons and in a variety of postembryonic organ and meristem boundaries. This gene, CUP-SHAPED COTYLEDON3 (CUC3...... revealing an even higher degree of redundancy in this class of genes than was thought previously. The CUC3 expression pattern, the cuc3 phenotypes, and CUC3 expression in a series of shoot meristem mutants and transgenes suggest a primary role for CUC3 in the establishment of boundaries that contain cells...

  17. Optimized Whole-Mount In Situ Immunolocalization for Arabidopsis thaliana Root Meristems and Lateral Root Primordia.

    Science.gov (United States)

    Karampelias, Michael; Tejos, Ricardo; Friml, Jiří; Vanneste, Steffen

    2018-01-01

    Immunolocalization is a valuable tool for cell biology research that allows to rapidly determine the localization and expression levels of endogenous proteins. In plants, whole-mount in situ immunolocalization remains a challenging method, especially in tissues protected by waxy layers and complex cell wall carbohydrates. Here, we present a robust method for whole-mount in situ immunolocalization in primary root meristems and lateral root primordia in Arabidopsis thaliana. For good epitope preservation, fixation is done in an alkaline paraformaldehyde/glutaraldehyde mixture. This fixative is suitable for detecting a wide range of proteins, including integral transmembrane proteins and proteins peripherally attached to the plasma membrane. From initiation until emergence from the primary root, lateral root primordia are surrounded by several layers of differentiated tissues with a complex cell wall composition that interferes with the efficient penetration of all buffers. Therefore, immunolocalization in early lateral root primordia requires a modified method, including a strong solvent treatment for removal of hydrophobic barriers and a specific cocktail of cell wall-degrading enzymes. The presented method allows for easy, reliable, and high-quality in situ detection of the subcellular localization of endogenous proteins in primary and lateral root meristems without the need of time-consuming crosses or making translational fusions to fluorescent proteins.

  18. Direct conversion of root primordium into shoot meristem relies on timing of stem cell niche development.

    Science.gov (United States)

    Rosspopoff, Olga; Chelysheva, Liudmila; Saffar, Julie; Lecorgne, Lena; Gey, Delphine; Caillieux, Erwann; Colot, Vincent; Roudier, François; Hilson, Pierre; Berthomé, Richard; Da Costa, Marco; Rech, Philippe

    2017-04-01

    To understand how the identity of an organ can be switched, we studied the transformation of lateral root primordia (LRP) into shoot meristems in Arabidopsis root segments. In this system, the cytokinin-induced conversion does not involve the formation of callus-like structures. Detailed analysis showed that the conversion sequence starts with a mitotic pause and is concomitant with the differential expression of regulators of root and shoot development. The conversion requires the presence of apical stem cells, and only LRP at stages VI or VII can be switched. It is engaged as soon as cell divisions resume because their position and orientation differ in the converting organ compared with the undisturbed emerging LRP. By alternating auxin and cytokinin treatments, we showed that the root and shoot organogenetic programs are remarkably plastic, as the status of the same plant stem cell niche can be reversed repeatedly within a set developmental window. Thus, the networks at play in the meristem of a root can morph in the span of a couple of cell division cycles into those of a shoot, and back, through transdifferentiation. © 2017. Published by The Company of Biologists Ltd.

  19. Cryopreservation of in vitro grown shoot tips and apical meristems of the forage legume Arachis pintoi.

    Science.gov (United States)

    Rey, Hebe Y; Faloci, Mirta; Medina, Ricardo; Dolce, Natalia; Mroginski, Luis; Engelmann, Florent

    2009-01-01

    A cryopreservation protocol using the encapsulation-dehydration procedure was established for shoot tips (2-3 mm in length) and meristems (0.3-0.5 mm) sampled from in vitro plantlets of diploid and triploid cytotypes of Arachis pintoi. The optimal protocol was the following: after dissection, explants were precultured for 24 h on establishment medium (EM), encapsulated in calcium alginate beads and pretreated in liquid EM medium with daily increasing sucrose concentration (0.5, 0.75, 1.0 M) and desiccated to 22-23 percent moisture content (fresh weight basis). Explants were frozen using slow cooling (1 C per min from 25C to -30C followed by direct immersion in liquid nitrogen), thawed rapidly and post-cultured in liquid EM medium enriched with daily decreasing sucrose concentrations (0.75, 0.50, 0.1 M). Explants were then transferred to solid EM medium in order to achieve shoot regeneration, then on Murashige and Skoog medium supplemented with 0.05 microM naphthalene acetic acid to induce rooting of shoots. With this procedure, 53 percent and 56 percent of cryopreserved shoot tips of the diploid and triploid cytotypes, respectively, survived and formed plants. However, only 16 percent of cryopreserved meristems of both cytotypes regenerated plants. Using ten isozyme systems and seven RAPD profiles, no modification induced by cryopreservation could be detected in plantlets regenerated from cryopreserved material.

  20. Redox Changes During the Cell Cycle in the Embryonic Root Meristem of Arabidopsis thaliana.

    Science.gov (United States)

    de Simone, Ambra; Hubbard, Rachel; de la Torre, Natanael Viñegra; Velappan, Yazhini; Wilson, Michael; Considine, Michael J; Soppe, Wim J J; Foyer, Christine H

    2017-12-20

    The aim of this study was to characterize redox changes in the nuclei and cytosol occurring during the mitotic cell cycle in the embryonic roots of germinating Arabidopsis seedlings, and to determine how redox cycling was modified in mutants with a decreased capacity for ascorbate synthesis. Using an in vivo reduction-oxidation (redox) reporter (roGFP2), we show that transient oxidation of the cytosol and the nuclei occurred at G1 in the synchronized dividing cells of the Arabidopsis root apical meristem, with reduction at G2 and mitosis. This redox cycle was absent from low ascorbate mutants in which nuclei were significantly more oxidized than controls. The cell cycle-dependent increase in nuclear size was impaired in the ascorbate-deficient mutants, which had fewer cells per unit area in the root proliferation zone. The transcript profile of the dry seeds and size of the imbibed seeds was strongly influenced by low ascorbate but germination, dormancy release and seed aging characteristics were unaffected. These data demonstrate the presence of a redox cycle within the plant cell cycle and that the redox state of the nuclei is an important factor in cell cycle progression. Controlled oxidation is a key feature of the early stages of the plant cell cycle. However, sustained mild oxidation restricts nuclear functions and impairs progression through the cell cycle leading to fewer cells in the root apical meristem. Antioxid. Redox Signal. 27, 1505-1519.

  1. Analysis of Transcriptional Responses of the Inflorescence Meristems in Jatropha curcas Following Gibberellin Treatment

    Directory of Open Access Journals (Sweden)

    Wen-Kai Hui

    2018-02-01

    Full Text Available Jatropha curcas L. seeds an oilseed plant with great potential for biodiesel production. However, low seed yield, which was limited by its lower female flowers, was a major drawback for its utilization. Our previous study found that the flower number and female-to-male ratio were increased by gibberellin treatment. Here, we compared the transcriptomic profiles of inflorescence meristem at different time points after gibberellic acid A3 (GA3 treatment. The present study showed that 951 differentially expressed genes were obtained in response to gibberellin treatment, compared with control samples. The 6-h time point was an important phase in the response to exogenous gibberellin. Furthermore, the plant endogenous gibberellin, auxin, ethylene, abscisic acid, and brassinolide-signaling transduction pathways were repressed, whereas the genes associated with cytokinin and jasmonic acid signaling were upregulated for 24-h time point following GA3 treatment. In addition, the floral meristem determinacy genes (JcLFY, JcSOC1 and floral organ identity genes (JcAP3, JcPI, JcSEP1-3 were significantly upregulated, but their negative regulator (JcSVP was downregulated after GA3 treatment. Moreover, the effects of phytohormone, which was induced by exogenous plant growth regulator, mainly acted on the female floral differentiation process. To the best of our knowledge, this data is the first comprehensive analysis of the underlying transcriptional response mechanism of floral differentiation following GA3 treatment in J. curcas, which helps in engineering high-yielding varieties of Jatropha.

  2. The histone acetyltransferase GCN5 affects the inflorescence meristem and stamen development in Arabidopsis.

    Science.gov (United States)

    Cohen, Ross; Schocken, John; Kaldis, Athanasios; Vlachonasios, Konstantinos E; Hark, Amy T; McCain, Elizabeth R

    2009-11-01

    A central question in biology is to understand how gene expression is precisely regulated to give rise to a variety of forms during the process of development. Epigenetic effects such as DNA methylation or histone modification have been increasingly shown to play a critical role in regulation of genome function. GCN5 is a prototypical histone acetyltransferase that participates in regulating developmental gene expression in several metazoan species. In Arabidopsis thaliana, plants with T-DNA insertions in GCN5 (also known as HAG1) display a variety of pleiotropic effects including dwarfism, loss of apical dominance, and floral defects affecting fertility. We sought to determine when during early development floral abnormalities first arise. Using scanning electron microscopy, we demonstrate that gcn5-1/hag1-1 and gcn5-5/hag1-5 mutants display overproliferation of young buds and development of abnormal structures around the inflorescence meristem. gcn5 mutants also display defects in stamen number and arrangement at later stages. This analysis provides temporal and spatial information to aid in the identification of GCN5 target genes in the developing flower. Preliminary studies of putative targets using reverse transcriptase PCR suggest that the floral meristem identity gene LEAFY is among factors upregulated in gcn5-1 mutants.

  3. Arabidopsis shoot apical meristem development after ipt transcriptional activation in pOp/LhG4 system

    Czech Academy of Sciences Publication Activity Database

    Dubová, J.; Ryšavá, Hana; Reková, Alena; Brzobohatý, Břetislav

    2005-01-01

    Roč. 49, - (2005), S22 [2nd International Symposium Auxins and Cytokinins in Plant Development. Prague, 07.07.2005-12.07.2005] R&D Projects: GA AV ČR(CZ) IAA600380507 Institutional research plan: CEZ:AV0Z50040507 Keywords : shoot apical meristem * cytokinin Subject RIV: BO - Biophysics

  4. Cytokinin regulates the activity of reproductive meristems, flower organ size, ovule formation, and thus seed yield in Arabidopsis thaliana

    Czech Academy of Sciences Publication Activity Database

    Bartrina, I.; Otto, E.; Strnad, Miroslav; Werner, T.; Schmülling, T.

    2011-01-01

    Roč. 23, č. 1 (2011), s. 69-80 ISSN 1040-4651 R&D Projects: GA ČR GA301/08/1649 Institutional research plan: CEZ:AV0Z50380511 Keywords : SHOOT APICAL MERISTEM * STEM-CELL FATE * RESPONSE REGULATORS * PLANT DEVELOPMENT * HOMEOBOX GENES Subject RIV: EF - Botanics Impact factor: 8.987, year: 2011

  5. Specification of reproductive meristems requires the combined function of SHOOT MERISTEMLESS and floral integrators FLOWERING LOCUS T and FD during Arabidopsis inflorescence development.

    Science.gov (United States)

    Smith, Harley M S; Ung, Nolan; Lal, Shruti; Courtier, Jennifer

    2011-01-01

    In Arabidopsis floral meristems are specified on the periphery of the inflorescence meristem by the combined activities of the FLOWERING LOCUS T (FT)-FD complex and the flower meristem identity gene LEAFY. The floral specification activity of FT is dependent upon two related BELL1-like homeobox (BLH) genes PENNYWISE (PNY) and POUND-FOOLISH (PNF) which are required for floral evocation. PNY and PNF interact with a subset of KNOTTED1-LIKE homeobox proteins including SHOOT MERISTEMLESS (STM). Genetic analyses show that these BLH proteins function with STM to specify flowers and internodes during inflorescence development. In this study, experimental evidence demonstrates that the specification of flower and coflorescence meristems requires the combined activities of FT-FD and STM. FT and FD also regulate meristem maintenance during inflorescence development. In plants with reduced STM function, ectopic FT and FD promote the formation of axillary meristems during inflorescence development. Lastly, gene expression studies indicate that STM functions with FT-FD and AGAMOUS-LIKE 24 (AGL24)-SUPPRESSOR OF OVEREXPRESSION OF CONTANS1 (SOC1) complexes to up-regulate flower meristem identity genes during inflorescence development.

  6. Cytokinin-induced promotion of root meristem size in the fern Azolla supports a shoot-like origin of euphyllophyte roots

    NARCIS (Netherlands)

    de Vries, Jan; Fischer, Angela Melanie; Roettger, Mayo; Rommel, Sophie; Schlupmann, Henriette|info:eu-repo/dai/nl/304827819; Bräutigam, Andrea; Carlsbecker, Annelie; Gould, Sven Bernhard

    The phytohormones cytokinin and auxin orchestrate the root meristem development in angiosperms by determining embryonic bipolarity. Ferns, having the most basal euphyllophyte root, form neither bipolar embryos nor permanent embryonic primary roots but rather an adventitious root system. This raises

  7. Organogênese de ápices meristemáticos de batata em meios de isolamento e multiplicação in vitro Organogenesis of potato meristem tips on the in vitro isolation and multiplication media

    Directory of Open Access Journals (Sweden)

    Jonny Everson Scherwinski Pereira

    2004-06-01

    Full Text Available Estudou-se a influência da consistência do meio de cultura sobre a organogênese de ápices meristemáticos de batata nas etapas de isolamento e multiplicação in vitro, das cultivares Baronesa, Eliza e Pérola. Para o cultivo utilizaram-se tubos de ensaio (20 x 150 mm contendo 5 ml de meio de cultura de isolamento (sais de MS, 30g.L-1 sacarose, 1,0 mg.L-1 BAP, 0,01mg.L-1 ANA, 0,1 mg.L-1 AG3 de consistência semi-sólida (6g.L-1 de ágar ou líquida. Ao meio de cultura semi-sólido acrescentou-se ainda 300 mg.L-1 de carvão ativado. Como suporte dos meristemas em meio líquido, foram introduzidas fitas de papel filtro em forma de "U" invertido. Após 30 dias em meio de isolamento, os meristemas diferenciados foram transferidos para meio de multiplicação (sais de MS, 1,0 mg.L-1 de tiamina, 5,0 mg.L-1 de ácido pantotênico, 0,25 mg.L-1 de AG3 e 20 g.L-1 de sacarose semi-sólido e líquido, onde permaneceram por mais 21 dias. O desenvolvimento dos meristemas em meio de multiplicação de consistência líquida proporcionou brotações com altura, pelo menos, quatro vezes superior àquelas desenvolvidas em meio semi-sólido. A taxa de multiplicação obtida em meio líquido foi 1,6 e 3,6 vezes superior ao meio semi-sólido quando os meristemas diferenciaram-se em meio de isolamento líquido e semi-sólido, respectivamente. Houve formação indesejável de calo na base dos meristemas desenvolvidos em meio de isolamento líquido, o que proporcionou maior número de brotações regeneradas nestes meristemas. A diferenciação de meristemas de batata em meio de isolamento semi-sólido por 30 dias, seguida do cultivo em meio líquido sob agitação por mais 21 dias, promove melhoria nas taxas de crescimento e multiplicação dos meristemas.The effect of the culture media consistency on the organogenesis of potato meristem tips was evaluated on the in vitro isolation and multiplication stages from cultivars Baronesa, Eliza and Perola. The meristems

  8. Effect of 6-BAP and IAA in meristems in vitro establishment of Colocasia esculenta (L Schott 'INIVIT MC 2012' cultivar

    Directory of Open Access Journals (Sweden)

    Arletys Santos Pino

    2017-01-01

    Full Text Available The use of meristems for the in vitro establishment of Colocasia esculenta (L. Schott cv. 'INIVIT MC-2012' decreases bacterial contamination but is required to increase its growth. The objective of this work was to determine the effect of 6-Benzylaminopurine and indoleacetic acid on its in vitro establishment. Various concentrations of the two growth regulators were included in the culture medium and with the best combination the explants were cultured in shaking and static liquid culture medium. With the use of the culture medium constituted by 80% of the salts and vitamins MS, 30 g l-1 sucrose, 0.1 g l-1 myo-inositol, 0.1 mg l-1 6-BAP, 0.05 mg l-1 of AIA and culture in agitation were obtained meristems with the appropriate morphological characteristics to transfer to the multiplication phase at 28 days of culture. Keywords: orbital agitator, propagation, taro

  9. Transcriptome of the inflorescence meristems of the biofuel plant Jatropha curcas treated with cytokinin.

    Science.gov (United States)

    Pan, Bang-Zhen; Chen, Mao-Sheng; Ni, Jun; Xu, Zeng-Fu

    2014-11-17

    Jatropha curcas, whose seed content is approximately 30-40% oil, is an ideal feedstock for producing biodiesel and bio-jet fuels. However, Jatropha plants have a low number of female flowers, which results in low seed yield that cannot meet the needs of the biofuel industry. Thus, increasing the number of female flowers is critical for the improvement of Jatropha seed yield. Our previous findings showed that cytokinin treatment can increase the flower number and female to male ratio and also induce bisexual flowers in Jatropha. The mechanisms underlying the influence of cytokinin on Jatropha flower development and sex determination, however, have not been clarified. This study examined the transcriptional levels of genes involved in the response to cytokinin in Jatropha inflorescence meristems at different time points after cytokinin treatment by 454 sequencing, which gave rise to a total of 294.6 Mb of transcript sequences. Up-regulated and down-regulated annotated and novel genes were identified, and the expression levels of the genes of interest were confirmed by qRT-PCR. The identified transcripts include those encoding genes involved in the biosynthesis, metabolism, and signaling of cytokinin and other plant hormones, flower development and cell division, which may be related to phenotypic changes of Jatropha in response to cytokinin treatment. Our analysis indicated that Jatropha orthologs of the floral organ identity genes known as ABCE model genes, JcAP1,2, JcPI, JcAG, and JcSEP1,2,3, were all significantly repressed, with an exception of one B-function gene JcAP3 that was shown to be up-regulated by BA treatment, indicating different mechanisms to be involved in the floral organ development of unisexual flowers of Jatropha and bisexual flowers of Arabidopsis. Several cell division-related genes, including JcCycA3;2, JcCycD3;1, JcCycD3;2 and JcTSO1, were up-regulated, which may contribute to the increased flower number after cytokinin treatment. This study

  10. Cytokinin-induced promotion of root meristem size in the fern Azolla supports a shoot-like origin of euphyllophyte roots.

    Science.gov (United States)

    de Vries, Jan; Fischer, Angela Melanie; Roettger, Mayo; Rommel, Sophie; Schluepmann, Henriette; Bräutigam, Andrea; Carlsbecker, Annelie; Gould, Sven Bernhard

    2016-01-01

    The phytohormones cytokinin and auxin orchestrate the root meristem development in angiosperms by determining embryonic bipolarity. Ferns, having the most basal euphyllophyte root, form neither bipolar embryos nor permanent embryonic primary roots but rather an adventitious root system. This raises the questions of how auxin and cytokinin govern fern root system architecture and whether this can tell us something about the origin of that root. Using Azolla filiculoides, we characterized the influence of IAA and zeatin on adventitious fern root meristems and vasculature by Nomarski microscopy. Simultaneously, RNAseq analyses, yielding 36,091 contigs, were used to uncover how the phytohormones affect root tip gene expression. We show that auxin restricts Azolla root meristem development, while cytokinin promotes it; it is the opposite effect of what is observed in Arabidopsis. Global gene expression profiling uncovered 145 genes significantly regulated by cytokinin or auxin, including cell wall modulators, cell division regulators and lateral root formation coordinators. Our data illuminate both evolution and development of fern roots. Promotion of meristem size through cytokinin supports the idea that root meristems of euphyllophytes evolved from shoot meristems. The foundation of these roots was laid in a postembryonically branching shoot system. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

  11. Inhibition of tobacco mosaic virus replication in lateral roots is dependent on an activated meristem-derived signal.

    Science.gov (United States)

    Valentine, T A; Roberts, I M; Oparka, K J

    2002-05-01

    Viral invasion of the root system of Nicotiana benthamiana was studied noninvasively with a tobacco mosaic virus (TMV) vector expressing the green-fluorescent protein (GFP). Lateral root primordia, which developed from the pericycle of primary roots, became heavily infected as they emerged from the root cortex. However, following emergence, a progressive wave of viral inhibition occurred that originated in the lateral-root meristem and progressed towards its base. Excision of source and sink tissues suggested that the inhibition of virus replication was brought about by the basipetal movement of a root meristem signal. When infected plants were inoculated with tobacco rattle virus (TRV) expressing the red-fluorescent protein, DsRed, TRV entered the lateral roots and suppressed the host response, leading to a reestablishment of TMV infection in lateral roots. By infecting GFP-expressing transgenic plants with TMV carrying the complementary GFP sequence it was possible to silence the host GFP, leading to the complete loss of fluorescence in lateral roots. The data suggest that viral inhibition in lateral roots occurs by a gene-silencing-like mechanism that is dependent on the activation of a lateral-root meristem.

  12. Single-cell telomere-length quantification couples telomere length to meristem activity and stem cell development in Arabidopsis.

    Science.gov (United States)

    González-García, Mary-Paz; Pavelescu, Irina; Canela, Andrés; Sevillano, Xavier; Leehy, Katherine A; Nelson, Andrew D L; Ibañes, Marta; Shippen, Dorothy E; Blasco, Maria A; Caño-Delgado, Ana I

    2015-05-12

    Telomeres are specialized nucleoprotein caps that protect chromosome ends assuring cell division. Single-cell telomere quantification in animals established a critical role for telomerase in stem cells, yet, in plants, telomere-length quantification has been reported only at the organ level. Here, a quantitative analysis of telomere length of single cells in Arabidopsis root apex uncovered a heterogeneous telomere-length distribution of different cell lineages showing the longest telomeres at the stem cells. The defects in meristem and stem cell renewal observed in tert mutants demonstrate that telomere lengthening by TERT sets a replicative limit in the root meristem. Conversely, the long telomeres of the columella cells and the premature stem cell differentiation plt1,2 mutants suggest that differentiation can prevent telomere erosion. Overall, our results indicate that telomere dynamics are coupled to meristem activity and continuous growth, disclosing a critical association between telomere length, stem cell function, and the extended lifespan of plants. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

  13. ELIMINATION OF Cucumber Mozaic Virus (CMV FROM A RANGE OF CHRYSANTHEMUM CULTIVARS THROUGH MERISTEM CULTURE FOLLOWING HEAT TREATMENT

    Directory of Open Access Journals (Sweden)

    Kurniawan Budiarto

    2011-11-01

    Full Text Available Cucumber Mosaic Virus (CMV is one of pathogenic viruses that commonly found and has caused significant losses in many chrysanthemum growers in Indonesia.  Efforts have been made to get healthy plant source through eliminating virus from infected plants and one of the promising methods was the combination of thermotherapy and meristem culture. The research was conducted to find out the effect of meristem culture following heat treatments on the existence of CMV in infected chrysanthemum plantlets. The experiment was carried out in the laboratory of tissue culture and virology at The Indonesian Ornamental Crops Research Institute (IOCRI from August 2007 until June 2008. A complete factorial with ten replications was designed to accomplish the combination of two factors.  The first factor was three chrysanthemum cultivars, namely Stroika, Dewi Sartika and White Fiji, while the second dealt with the durations of heat treatment i.e. one, two and three weeks.  The results showed that plantlet survival decreased, yet improved plantlet performance by faster bud initiation with lengthened heat duration.  The percentage of virus-free planlets also increased along with the duration of treatment and three weeks heat treatment followed by meristem culture effectively eliminated CMV from infected planlets.

  14. ELIMINATION OF CVB ( FROM A RANGE OF CHRYSANTHEMUM VARIETIES BY APICAL MERISTEM CULTURE FOLLOWING ANTIVIRAL AGENT AND HEAT TREATMENTS

    Directory of Open Access Journals (Sweden)

    KURNIAWAN BUDIARTO

    2011-09-01

    Full Text Available CVB elimination for retaining healthy protocols from infected chrysanthemum plant wasinvestigated through combined treatment of meristem culture with synthetic antiviral ribavirinor thermotherapy under conditions. The biological materials used for the experimentconstituted of six commercial varieties: Dewi Sartika, Saraswati, Yellow Fiji, White Puma,Yellow Puma and White Reagent. Tissue culture initiation was conducted through plantletestablishment using MS supplemented with IAA. Ribavirin was added in media with theconcentration of 40 mg/l on cv. Dewi Sartika, Saraswati and Yellow Fiji. Parallel with this step,heat treatment with different durations (1, 2, and 3 weeks was also conducted on the plantletson White Puma, Yellow Puma and White Reagent. Meristem culture was done followingthe chemo- and thermotherapy. The experiment resumed the failure of single treatment ofmeristem culture in eliminating CVB from the infected chrysanthemum plantlets. Under heattreatment, percentage of virus-free plantlets increased along with the duration ofthermotherapy, though the survival rate of plantlets decreased in lengthened heat treatment.The best results regarding virus free plant percentage were obtained when meristem culture wasapplied following ribavirin or three weeks of heat treatment.

  15. TCPs, WUSs, and WINDs: Families of transcription factors that regulate shoot meristem formation, stem cell maintenance, and somatic cell differentiation

    Directory of Open Access Journals (Sweden)

    Miho eIkeda

    2014-09-01

    Full Text Available In contrast to somatic mammalian cells, which cannot alter their fate, plant cells can dedifferentiate to form totipotent callus cells and regenerate a whole plant, following treatment with specific phytohormones. However, the regulatory mechanisms and key factors that control differentiation-dedifferentiation and cell totipotency have not been completely clarified in plants. Recently, several plant transcription factors that regulate meristem formation and dedifferentiation have been identified and include members of the TEOSINTE BRANCHED1/CYCLOIDEA/PROLIFERATING CELL FACTOR (TCP, WUSCHEL (WUS, and WOUND INDUCED DEDIFFERENTIATION (WIND1 families. WUS and WIND positively control plant cell totipotency, while TCP negatively controls it. Interestingly, TCP is a transcriptional activator that acts as a negative regulator of shoot meristem formation, and WUS is a transcriptional repressor that positively maintains totipotency of the stem cells of the shoot meristem. We describe here the functions of TCP, WUS and WIND transcription factors in the regulation of differentiation-dedifferentiation by positive and negative transcriptional regulators.

  16. Effect of growth regulators in meristem culture of potato (solanum tuberosmum l.)

    International Nuclear Information System (INIS)

    Batool, A.; Zaidi, S.S.H.

    2014-01-01

    Two growth regulators, viz., Gibberellic acid (GA3) and Naphthalene acetic acid (NAA) and a combination of both (GA3 and NAA) were evaluated at three different levels (200, 300 and 400 meul) to check the growth rate of root, shoot, number of leaves and nodes of potato plantlets in two potato varieties, namely cardinal and SH-5, grown by meristem culture. Analysis of variance revealed highly significant differences between varieties, hormones and their interaction for all the studied traits. Mean values revealed that among two varieties Cardinal produced root length (0.70 cm), shoot length (2.50 cm), number of leaves (6.96) and number of nodes (8) are better than the SH-5 which produced root length (0.54 cm), shoot length (1.38 cm), number of leaves (4.29) and number of nodes (5.3). The variety cardinal and GA3 at 300 meul followed by 200 meul produced most suitable results. By using the concentration of 300 meul maximum root length of (1.40 cm), shoot length of (3.43 cm), number of leaves (10) and no of nodes (11) was obtained. At 200 meul, though root and shoot length obtained was very similar at 300 meul but produced less number of leaves and nodes. (author)

  17. Dataset of Arabidopsis plants that overexpress FT driven by a meristem-specific KNAT1 promoter

    Directory of Open Access Journals (Sweden)

    L. Duplat-Bermúdez

    2016-09-01

    Full Text Available In this dataset we integrated figures comparing leaf number and rosette diameter in three Arabidopsis FT overexpressor lines (AtFTOE driven by KNAT1 promoter, “A member of the KNOTTED class of homeodomain proteins encoded by the STM gene of Arabidopsis” [5], vs Wild Type (WT Arabidopsis plats. Also, presented in the tables are some transcriptomic data obtained by RNA-seq Illumina HiSeq from rosette leaves of Arabidopsis plants of AtFTOE 2.1 line vs WT with accession numbers SRR2094583 and SRR2094587 for AtFTOE replicates 1–3 and AtWT for control replicates 1–2 respectively. Raw data of paired-end sequences are located in the public repository of the National Center for Biotechnology Information of the National Library of Medicine, National Institutes of Health, United States of America, Bethesda, MD, USA as Sequence Read Archive (SRA. Performed analyses of differential expression genes are visualized by Mapman and presented in figures. “Transcriptomic analysis of Arabidopsis overexpressing flowering locus T driven by a meristem-specific promoter that induces early flowering” [2], described the interpretation and discussion of the obtained data.

  18. MERISTEM DISORGANIZATION1 encodes TEN1, an essential telomere protein that modulates telomerase processivity in Arabidopsis.

    Science.gov (United States)

    Leehy, Katherine A; Lee, Jung Ro; Song, Xiangyu; Renfrew, Kyle B; Shippen, Dorothy E

    2013-04-01

    Telomeres protect chromosome ends from being recognized as DNA damage, and they facilitate the complete replication of linear chromosomes. CST [for CTC1(Cdc13)/STN1/TEN1] is a trimeric chromosome end binding complex implicated in both aspects of telomere function. Here, we characterize TEN1 in the flowering plant Arabidopsis thaliana. We report that TEN1 (for telomeric pathways in association with Stn1, which stands for suppressor of cdc thirteen) is encoded by a previously characterized gene, MERISTEM DISORGANIZATION1 (MDO1). A point mutation in MDO1, mdo1-1/ten1-3 (G77E), triggers stem cell differentiation and death as well as a constitutive DNA damage response. We provide biochemical and genetic evidence that ten1-3 is likely to be a null mutation. As with ctc1 and stn1 null mutants, telomere tracts in ten1-3 are shorter and more heterogeneous than the wild type. Mutants also exhibit frequent telomere fusions, increased single-strand telomeric DNA, and telomeric circles. However, unlike stn1 or ctc1 mutants, telomerase enzyme activity is elevated in ten1-3 mutants due to an increase in repeat addition processivity. In addition, TEN1 is detected at a significantly smaller fraction of telomeres than CTC1. These data indicate that TEN1 is critical for telomere stability and also plays an unexpected role in modulating telomerase enzyme activity.

  19. Brachytic2/ZmABCB1 functions in IAA export from intercalary meristems

    Science.gov (United States)

    Knöller, Anne Sophie; Richards, Elizabeth L.; Peer, Wendy Ann; Murphy, Angus S.

    2010-01-01

    Dwarfism traits in Zea mays are regulated by multiple factors including the hormone auxin. Dwarf brachytic2 (br2) mutants harbour lesions in the gene encoding an orthologue of Arabidopsis thaliana ABCB1 which functions in auxin efflux out of meristematic regions in the shoot and root. br2 mesocotyls and coleoptiles exhibit reduced auxin transport. However, the dwarf stature of br2 derives from shortened lower internodes whilst the upper portion of the plant is completely normal. As such, it is counter-intuitive to attribute br2 dwarfism exclusively to reduced auxin export out of the shoot apex. Arabidopsis abcb1 mutants exhibit only minor reductions in auxin transport and plant height unless combined with mutations in the ABCB19 auxin transporter. Phylogenetic modelling analysis excludes the possibility that BR2 is more closely related to ABCB19 which has three more closely related orthologues in maize. BR2 is expressed in nodal meristems, and analyses of auxin transport and content indicate that BR2 function in these grass-specific tissues is analogous to ABCB1 function in the shoot and root apex of Arabidopsis. These results indicate that ABCB1/BR2 function is conserved between dicots and monocots, but also suggests that this function must be understood in the context of the segmental organization of grass plants. PMID:20581123

  20. Transformation of Inhibitor of Meristem Activity (IMA Gene into Jatropha curcas L.

    Directory of Open Access Journals (Sweden)

    Asri Pirade Paserang

    2015-09-01

    Full Text Available Jatropha is one of the many biodiesel plants developed in tropical countries. Efforts to increase its productivity can be done using various methods of breeding. One of the breeding methods is the introduction of genes into the Jatropha plant. The aim of this study is to assess the success of genetic transformation using the Inhibitor of Meristem Activity (IMA gene in Jatropha curcas. The research procedures included inoculation of explants with Agrobacterium tumefaciens, callus induction, screening test of selection media, regeneration, and gene expression analysis using Polymerase Chain Reaction (PCR. IMA is one of the genes that controls flowering genes and ovule development. It was first isolated from tomato plants and has been successfully overexpressed in these plants using the Cauliflower Mosaic Virus (CaMV 35S promoter. In this experiment, plant transformation was performed on J. curcas as the target. Explant callus formation in both the control and treated samples was good, but shoot formation decreased dramatically in the treated explants. PCR analysis indicated that IMA genes can be inserted into J. curcas with the size of the IMA gene is 500 bp.

  1. Unique cell-type specific patterns of DNA methylation in the root meristem

    Science.gov (United States)

    Kawakatsu, Taiji; Stuart, Tim; Valdes, Manuel; Breakfield, Natalie; Schmitz, Robert J.; Nery, Joseph R.; Urich, Mark A.; Han, Xinwei; Lister, Ryan; Benfey, Philip N.; Ecker, Joseph R.

    2016-01-01

    DNA methylation is an epigenetic modification that differs between plant organs and tissues, but the extent of variation between cell types is not known. Here, we report single-base resolution whole genome DNA methylomes, mRNA transcriptomes, and small RNA transcriptomes for six cell populations covering the major cell types of the Arabidopsis root meristem. We identify widespread cell type specific patterns of DNA methylation, especially in the CHH sequence context. The genome of the columella root cap is the most highly methylated Arabidopsis cell characterized to date. It is hypermethylated within transposable elements, accompanied by increased abundance of transcripts encoding RNA-directed DNA methylation (RdDM) pathway components and 24 nt small RNAs. Absence of the nucleosome remodeler DECREASED DNA METHYLATION 1, required for maintenance of DNA methylation, and low abundance of histone transcripts involved in heterochromatin formation suggests a loss of heterochromatin may occur in the columella, thus allowing access of RdDM factors to the whole genome, and producing excess 24 nt small RNAs in this tissue. Together, these maps provide new insights into the epigenomic diversity that exists between distinct plant somatic cell types. PMID:27243651

  2. MERISTEM STRUCTURE, DEVELOPMENT OF CONES AND MICROSPOROGENESIS OF TEHRAN PINE (PINUS ELDARICA Medw.

    Directory of Open Access Journals (Sweden)

    Ahmad MAJD

    2014-12-01

    Full Text Available Tehran pine (Pinus eldarica Medw. belongs to Pinaceae family with significant economic and ecological benefits. To gain further insight into anatomical-developmental structure of P. eldarica, both the vegetative and generative meristematic tissues and microsporogenesis were been studied during certain stages of development. To do this, meristematic tissues and male cones were initially fixed in FAA solution (37% formaldehyde, 96% ethanol and glacial acetic acid with a 2:7:1 ratio, respectively. They were then embedded in paraffin and sectioned using a rotary microtome. Prior to visualization and photography under a camera-equipped light microscope, they were stained with hematoxylin-eosin (Zeiss model. Our results revealed the vegetative meristem of P. eldarica to be in the Cryptomerya-Abies category. The results also indicated it is a protuberant (dome-like type containing four regions. The meiosis occurs before the winter dormancy and continues through the winter. The pollen is shed at the four-cell stage of development.

  3. Cytotoxicity of Cheese and Cheddar Cheese food flavorings on Allim cepa L root meristems

    Directory of Open Access Journals (Sweden)

    A. G. Moura

    Full Text Available Abstract Despite their great importance for the food industry, flavorings, in general, raise a number of questions regarding their cytotoxicity, mutagenicity and carcinogenicity, since, in the literature, there are few studies found evaluating the toxicity on the systemic and cellular level, of these chemical compounds. The root meristems of Allium cepa (onion are widely used for the assessment of toxicity of chemical compounds of interest. Thus, this study aimed to evaluate, in A. cepa meristematic cells, individually and in combination at the cellular level, the toxicity of synthetic Cheese and Cheddar Cheese food flavorings, identical to the natural, at doses of 1.0 and 2.0 mL, at exposure times of 24 and 48 hours. In combination we used 0.5 mL of Cheese flavor associated with 0.5 mL of Cheddar flavor; and 1.0 mL of Cheese flavor associated with 1.0 mL of Cheddar flavor, at exposure times of 24 and 48 hours. For these evaluations, we used groups of five onion bulbs, which were first embedded in distilled water and then transferred to their respective doses. The root tips were collected and fixed in acetic acid (3:1 for 24 hours. The slides were prepared by crushing and were stained with 2% acetic orcein. Cells were analyzed throughout the cell cycle, totaling 5,000 for each control and exposure time. The mitotic indices calculated and cellular aberrations observed were subjected to statistical analysis using the chi-square test (p <0.05. No chromosomal abnormalities nor those of mitotic spindle were observed for the treatments performed. The results, both individually and in combination, showed that the flavorings under study significantly reduced the cell division rate of the test system cells used. Therefore, under the conditions studied, the two flavorings were cytotoxic.

  4. Auxin-cytokinin synergismin vitrofor producing genetically stable plants ofRuta graveolensusing shoot tip meristems.

    Science.gov (United States)

    Faisal, Mohammad; Ahmad, Naseem; Anis, Mohammad; Alatar, Abdulrahman A; Qahtan, Ahmad A

    2018-02-01

    An efficient micropropagation protocol was developed for Ruta graveolens Linn. using shoot tip meristems derived from a 4-month-old field grown plant. In vitro shoot regeneration and proliferation was accomplished on Murashige and Skoogs (MS) semi-solid medium in addition to different doses of cytokinins viz.6- benzyl adenine (BA), Kinetin (Kn) or 2-isopetynyl adenine (2iP), singly or in combination with auxins viz. indole-3-acetic acid (IAA), indole-3-butyric acid (IBA) or α-naphthalene acetic acid (NAA). Highest regeneration frequency (27.6%) was obtained on (MS) medium composed of BA (10 µM) with maximum number (9.4) of shoots and 4.3 cm shoot length after 4 weeks of incubation. Among various combinations tried best regeneration frequency (71%) of multiple shoot formation with highest number (12.6) of shoots per shoot tip explants were achieved in MS medium augmented with a combination BA (10.0 µM) and NAA (2.5 µM) after 4 weeks of incubation. The optimum frequency (97%) of rhizogenesis was achieved on half-strength MS medium having 0.5 µM IBA after 4 weeks of incubation. Tissue culture raised plantlets with 5-7 fully opened leaves with healthy root system were successfully acclimatized off in Soilrite™ with 80% survival rate followed by transportation to normal soil under natural light. Genetic stability among in vitro raised progeny was evaluated by ISSR and RAPD markers. The entire banding pattern revealed from in vitro regenerated plants was monomorphic to the donor. The present protocol provides an alternative option for commercial propagation and fruitful setting up of genetically uniform progeny for sustainable utilization and germplasm preservation.

  5. Gibberellin mediates daylength-controlled differentiation of vegetative meristems in strawberry (Fragaria x ananassa Duch).

    Science.gov (United States)

    Hytönen, Timo; Elomaa, Paula; Moritz, Thomas; Junttila, Olavi

    2009-02-11

    Differentiation of long and short shoots is an important developmental trait in several species of the Rosaceae family. However, the physiological mechanisms controlling this differentiation are largely unknown. We have studied the role of gibberellin (GA) in regulation of shoot differentiation in strawberry (Fragaria x ananassa Duch.) cv. Korona. In strawberry, differentiation of axillary buds to runners (long shoot) or to crown branches (short shoot) is promoted by long-day and short-day conditions, respectively. Formation of crown branches is a prerequisite for satisfactory flowering because inflorescences are formed from the apical meristems of the crown. We found that both prohexadione-calcium and short photoperiod inhibited runner initiation and consequently led to induction of crown branching. In both cases, this correlated with a similar decline in GA1 level. Exogenous GA3 completely reversed the effect of prohexadione-calcium in a long photoperiod, but was only marginally effective in short-day grown plants. However, transfer of GA3-treated plants from short days to long days restored the normal runner formation. This did not occur in plants that were not treated with GA3. We also studied GA signalling homeostasis and found that the expression levels of several GA biosynthetic, signalling and target genes were similarly affected by prohexadione-calcium and short photoperiod in runner tips and axillary buds, respectively. GA is needed for runner initiation in strawberry, and the inhibition of GA biosynthesis leads to the formation of crown branches. Our findings of similar changes in GA levels and in GA signalling homeostasis after prohexadione-calcium and short-day treatments, and photoperiod-dependent responsiveness of the axillary buds to GA indicate that GA plays a role also in the photoperiod-regulated differentiation of axillary buds. We propose that tightly regulated GA activity may control induction of cell division in subapical tissues of axillary

  6. Gibberellin mediates daylength-controlled differentiation of vegetative meristems in strawberry (Fragaria × ananassa Duch

    Directory of Open Access Journals (Sweden)

    Moritz Thomas

    2009-02-01

    Full Text Available Abstract Background Differentiation of long and short shoots is an important developmental trait in several species of the Rosaceae family. However, the physiological mechanisms controlling this differentiation are largely unknown. We have studied the role of gibberellin (GA in regulation of shoot differentiation in strawberry (Fragaria × ananassa Duch. cv. Korona. In strawberry, differentiation of axillary buds to runners (long shoot or to crown branches (short shoot is promoted by long-day and short-day conditions, respectively. Formation of crown branches is a prerequisite for satisfactory flowering because inflorescences are formed from the apical meristems of the crown. Results We found that both prohexadione-calcium and short photoperiod inhibited runner initiation and consequently led to induction of crown branching. In both cases, this correlated with a similar decline in GA1 level. Exogenous GA3 completely reversed the effect of prohexadione-calcium in a long photoperiod, but was only marginally effective in short-day grown plants. However, transfer of GA3-treated plants from short days to long days restored the normal runner formation. This did not occur in plants that were not treated with GA3. We also studied GA signalling homeostasis and found that the expression levels of several GA biosynthetic, signalling and target genes were similarly affected by prohexadione-calcium and short photoperiod in runner tips and axillary buds, respectively. Conclusion GA is needed for runner initiation in strawberry, and the inhibition of GA biosynthesis leads to the formation of crown branches. Our findings of similar changes in GA levels and in GA signalling homeostasis after prohexadione-calcium and short-day treatments, and photoperiod-dependent responsiveness of the axillary buds to GA indicate that GA plays a role also in the photoperiod-regulated differentiation of axillary buds. We propose that tightly regulated GA activity may control

  7. Gibberellin mediates daylength-controlled differentiation of vegetative meristems in strawberry (Fragaria × ananassa Duch)

    Science.gov (United States)

    Hytönen, Timo; Elomaa, Paula; Moritz, Thomas; Junttila, Olavi

    2009-01-01

    Background Differentiation of long and short shoots is an important developmental trait in several species of the Rosaceae family. However, the physiological mechanisms controlling this differentiation are largely unknown. We have studied the role of gibberellin (GA) in regulation of shoot differentiation in strawberry (Fragaria × ananassa Duch.) cv. Korona. In strawberry, differentiation of axillary buds to runners (long shoot) or to crown branches (short shoot) is promoted by long-day and short-day conditions, respectively. Formation of crown branches is a prerequisite for satisfactory flowering because inflorescences are formed from the apical meristems of the crown. Results We found that both prohexadione-calcium and short photoperiod inhibited runner initiation and consequently led to induction of crown branching. In both cases, this correlated with a similar decline in GA1 level. Exogenous GA3 completely reversed the effect of prohexadione-calcium in a long photoperiod, but was only marginally effective in short-day grown plants. However, transfer of GA3-treated plants from short days to long days restored the normal runner formation. This did not occur in plants that were not treated with GA3. We also studied GA signalling homeostasis and found that the expression levels of several GA biosynthetic, signalling and target genes were similarly affected by prohexadione-calcium and short photoperiod in runner tips and axillary buds, respectively. Conclusion GA is needed for runner initiation in strawberry, and the inhibition of GA biosynthesis leads to the formation of crown branches. Our findings of similar changes in GA levels and in GA signalling homeostasis after prohexadione-calcium and short-day treatments, and photoperiod-dependent responsiveness of the axillary buds to GA indicate that GA plays a role also in the photoperiod-regulated differentiation of axillary buds. We propose that tightly regulated GA activity may control induction of cell division in

  8. miR396 affects mycorrhization and root meristem activity in the legume Medicago truncatula.

    Science.gov (United States)

    Bazin, Jérémie; Khan, Ghazanfar Abbas; Combier, Jean-Philippe; Bustos-Sanmamed, Pilar; Debernardi, Juan Manuel; Rodriguez, Ramiro; Sorin, Céline; Palatnik, Javier; Hartmann, Caroline; Crespi, Martin; Lelandais-Brière, Christine

    2013-06-01

    The root system is crucial for acquisition of resources from the soil. In legumes, the efficiency of mineral and water uptake by the roots may be reinforced due to establishment of symbiotic relationships with mycorrhizal fungi and interactions with soil rhizobia. Here, we investigated the role of miR396 in regulating the architecture of the root system and in symbiotic interactions in the model legume Medicago truncatula. Analyses with promoter-GUS fusions suggested that the mtr-miR396a and miR396b genes are highly expressed in root tips, preferentially in the transition zone, and display distinct expression profiles during lateral root and nodule development. Transgenic roots of composite plants that over-express the miR396b precursor showed lower expression of six growth-regulating factor genes (MtGRF) and two bHLH79-like target genes, as well as reduced growth and mycorrhizal associations. miR396 inactivation by mimicry caused contrasting tendencies, with increased target expression, higher root biomass and more efficient colonization by arbuscular mycorrhizal fungi. In contrast to MtbHLH79, repression of three GRF targets by RNA interference severely impaired root growth. Early activation of mtr-miR396b, concomitant with post-transcriptional repression of MtGRF5 expression, was also observed in response to exogenous brassinosteroids. Growth limitation in miR396 over-expressing roots correlated with a reduction in cell-cycle gene expression and the number of dividing cells in the root apical meristem. These results link the miR396 network to the regulation of root growth and mycorrhizal associations in plants. © 2013 The Authors The Plant Journal © 2013 John Wiley & Sons Ltd.

  9. Effect of the gamma radiation in the metabolic activity of the apical meristem of asparagus (Asparagus officinalis)

    International Nuclear Information System (INIS)

    Sanchez E, A.; Orozco A, J.A.; Troncoso R, R.; Ojeda C, A.J.; Mercado R, J.N.; Gardea B, A.; Tiznado H, M.E.; Melendrez A, R.

    2007-01-01

    The asparagus (Asparagus officinalis) is an agricultural product whose production generates a great quantity of wages as well as foreign currencies for the country because a great part of its production is exported to international markets. In direct reason to the high metabolic activity of the apical meristem, this product it possesses a short shelf life under good conditions of commercialization. Due to the above mentioned, the present work had as objective to evaluate the effect of the gamma radiation in the metabolic activity of the apical meristem of turions of asparagus during the postharvest. Turions of asparagus variety Brock of standard quality was treated with gamma radiation to absorbed dose of 1.0, 1.5, 2.0, 2.5 and 3.0 kGy using an irradiator of 60 Co and stored in one controlled temperature camera maintained at 2 C during 8 days. During the experiment, the camera stayed in darkness and under conditions of high relative humidity by means of the water aspersion. Immediately before the one treatment and after 1, 2, 4 and 8 days of storage, the asparagus were sampled to evaluate the breathing speed (VRCG) by means of gas chromatography and scanning differential calorimetry (VRCDB), ethylene production (PE) by means of gas chromatography and production of metabolic heat of the apical meristem of the asparagus by means of scanning differential calorimetry (Q). Its were not found effects due to the gamma radiation in the variables of VRCG, VRCDB and Q. However, for the PE case, it was found that the doses of 1.5 and 2.5 reduced the PE from the first day of storage, while the 3 kGy dose achievement to eliminate completely the ethylene production from the first day of storage. It was concluded that the gamma radiation at the used levels in the present experiment doesn't reduce the metabolic activity of the apical meristem of the turion of asparagus although it can to improve the postharvest quality from the asparagus when reducing the ethylene production

  10. Auxin-cytokinin synergism in vitro for producing genetically stable plants of Ruta graveolens using shoot tip meristems

    OpenAIRE

    Mohammad Faisal; Naseem Ahmad; Mohammad Anis; Abdulrahman A. Alatar; Ahmad A. Qahtan

    2018-01-01

    An efficient micropropagation protocol was developed for Ruta graveolens Linn. using shoot tip meristems derived from a 4-month-old field grown plant. In vitro shoot regeneration and proliferation was accomplished on Murashige and Skoogs (MS) semi-solid medium in addition to different doses of cytokinins viz.6- benzyl adenine (BA), Kinetin (Kn) or 2-isopetynyl adenine (2iP), singly or in combination with auxins viz. indole-3-acetic acid (IAA), indole-3-butyric acid (IBA) or α-naphthalene acet...

  11. A dynamic genetic-hormonal regulatory network model explains multiple cellular behaviors of the root apical meristem of Arabidopsis thaliana.

    Science.gov (United States)

    García-Gómez, Mónica L; Azpeitia, Eugenio; Álvarez-Buylla, Elena R

    2017-04-01

    The study of the concerted action of hormones and transcription factors is fundamental to understand cell differentiation and pattern formation during organ development. The root apical meristem of Arabidopsis thaliana is a useful model to address this. It has a stem cell niche near its tip conformed of a quiescent organizer and stem or initial cells around it, then a proliferation domain followed by a transition domain, where cells diminish division rate before transiting to the elongation zone; here, cells grow anisotropically prior to their final differentiation towards the plant base. A minimal model of the gene regulatory network that underlies cell-fate specification and patterning at the root stem cell niche was proposed before. In this study, we update and couple such network with both the auxin and cytokinin hormone signaling pathways to address how they collectively give rise to attractors that correspond to the genetic and hormonal activity profiles that are characteristic of different cell types along A. thaliana root apical meristem. We used a Boolean model of the genetic-hormonal regulatory network to integrate known and predicted regulatory interactions into alternative models. Our analyses show that, after adding some putative missing interactions, the model includes the necessary and sufficient components and regulatory interactions to recover attractors characteristic of the root cell types, including the auxin and cytokinin activity profiles that correlate with different cellular behaviors along the root apical meristem. Furthermore, the model predicts the existence of activity configurations that could correspond to the transition domain. The model also provides a possible explanation for apparently paradoxical cellular behaviors in the root meristem. For example, how auxin may induce and at the same time inhibit WOX5 expression. According to the model proposed here the hormonal regulation of WOX5 might depend on the cell type. Our results

  12. A dynamic genetic-hormonal regulatory network model explains multiple cellular behaviors of the root apical meristem of Arabidopsis thaliana.

    Directory of Open Access Journals (Sweden)

    Mónica L García-Gómez

    2017-04-01

    Full Text Available The study of the concerted action of hormones and transcription factors is fundamental to understand cell differentiation and pattern formation during organ development. The root apical meristem of Arabidopsis thaliana is a useful model to address this. It has a stem cell niche near its tip conformed of a quiescent organizer and stem or initial cells around it, then a proliferation domain followed by a transition domain, where cells diminish division rate before transiting to the elongation zone; here, cells grow anisotropically prior to their final differentiation towards the plant base. A minimal model of the gene regulatory network that underlies cell-fate specification and patterning at the root stem cell niche was proposed before. In this study, we update and couple such network with both the auxin and cytokinin hormone signaling pathways to address how they collectively give rise to attractors that correspond to the genetic and hormonal activity profiles that are characteristic of different cell types along A. thaliana root apical meristem. We used a Boolean model of the genetic-hormonal regulatory network to integrate known and predicted regulatory interactions into alternative models. Our analyses show that, after adding some putative missing interactions, the model includes the necessary and sufficient components and regulatory interactions to recover attractors characteristic of the root cell types, including the auxin and cytokinin activity profiles that correlate with different cellular behaviors along the root apical meristem. Furthermore, the model predicts the existence of activity configurations that could correspond to the transition domain. The model also provides a possible explanation for apparently paradoxical cellular behaviors in the root meristem. For example, how auxin may induce and at the same time inhibit WOX5 expression. According to the model proposed here the hormonal regulation of WOX5 might depend on the cell

  13. AtREM1, a Member of a New Family of B3 Domain-Containing Genes, Is Preferentially Expressed in Reproductive Meristems1

    Science.gov (United States)

    Franco-Zorrilla, José M.; Cubas, Pilar; Jarillo, José A.; Fernández-Calvín, Begoña; Salinas, Julio; Martínez-Zapater, José M.

    2002-01-01

    We have isolated and characterized AtREM1, the Arabidopsis ortholog of the cauliflower (Brassica oleracea) BoREM1. AtREM1 belongs to a large gene family of more than 20 members in Arabidopsis. The deduced AtREM1 protein contains several repeats of a B3-related domain, and it could represent a new class of regulatory proteins only found in plants. Expression of AtREM1 is developmentally regulated, being first localized in a few central cells of vegetative apical meristems, and later expanding to the whole inflorescence meristem, as well as primordia and organs of third and fourth floral whorls. This specific expression pattern suggests a role in the organization of reproductive meristems, as well as during flower organ development. PMID:11842146

  14. Investigating the Molecular Mechanism of TSO1 Function in Arabidopsis cell division and meristem development

    Energy Technology Data Exchange (ETDEWEB)

    Zhongchi Liu

    2004-10-01

    Unlike animals, plants are constantly exposed to environmental mutagens including ultraviolet light and reactive oxygen species. Further, plant cells are totipotent with highly plastic developmental programs. An understanding of molecular mechanisms underlying the ability of plants to monitor and repair its DNA and to eliminate damaged cells are of great importance. Previously we have identified two genes, TSO1 and TSO2, from a flowering plant Arabidopsis thaliana. Mutations in these two genes cause callus-like flowers, fasciated shoot apical meristems, and abnormal cell division, indicating that TSO1 and TSO2 may encode important cell cycle regulators. Previous funding from DOE led to the molecular cloning of TSO1, which was shown to encode a novel nuclear protein with two CXC domains suspected to bind DNA. This DOE grant has allowed us to characterize and isolate TSO2 that encodes the small subunit of the ribonucleotide reductase (RNR). RNR comprises two large subunits (R1) an d two small subunits (R2), catalyzes a rate-limiting step in the production of deoxyribonucleotides needed for DNA replication and repair. Previous studies in yeast and mammals indicated that defective RNR often led to cell cycle arrest, growth retardation and p53-dependent apoptosis while abnormally elevated RNR activities led to higher mutation rates. Subsequently, we identified two additional R2 genes, R2A and R2B in the Arabidopsis genome. Using reverse genetics, mutations in R2A and R2B were isolated, and double and triple mutants among the three R2 genes (TSO2, R2A and R2B) were constructed and analyzed. We showed that Arabidopsis tso2 mutants, with reduced dNTP levels, were more sensitive to UV-C. While r2a or r2b single mutants did not exhibit any phenotypes, tso2 r2b double mutants were embryonic lethal and tso2 r2a double mutants were seedling lethal indicating redundant functions among the three R2 genes. Furthermore, tso2 r2a double mutants exhibited increased DNA dam age

  15. CENL1 expression in the rib meristem affects stem elongation and the transition to dormancy in Populus.

    Science.gov (United States)

    Ruonala, Raili; Rinne, Päivi L H; Kangasjärvi, Jaakko; van der Schoot, Christiaan

    2008-01-01

    We investigated the short day (SD)-induced transition to dormancy in wild-type hybrid poplar (Populus tremula x P. tremuloides) and its absence in transgenic poplar overexpressing heterologous PHYTOCHROME A (PHYA). CENTRORADIALIS-LIKE1 (CENL1), a poplar ortholog of Arabidopsis thaliana TERMINAL FLOWER1 (TFL1), was markedly downregulated in the wild-type apex coincident with SD-induced growth cessation. By contrast, poplar overexpressing a heterologous Avena sativa PHYA construct (P35S:AsPHYA), with PHYA accumulating in the rib meristem (RM) and adjacent tissues but not in the shoot apical meristem (SAM), upregulated CENL1 in the RM area coincident with an acceleration of stem elongation. In SD-exposed heterografts, both P35S:AsPHYA and wild-type scions ceased growth and formed buds, whereas only the wild type assumed dormancy and P35S:AsPHYA showed repetitive flushing. This shows that the transition is not dictated by leaf-produced signals but dependent on RM and SAM properties. In view of this, callose-enforced cell isolation in the SAM, associated with suspension of indeterminate growth during dormancy, may require downregulation of CENL1 in the RM. Accordingly, upregulation of CENL1/TFL1 might promote stem elongation in poplar as well as in Arabidopsis during bolting. Together, the results suggest that the RM is particularly sensitive to photoperiodic signals and that CENL1 in the RM influences transition to dormancy in hybrid poplar.

  16. CENL1 Expression in the Rib Meristem Affects Stem Elongation and the Transition to Dormancy in Populus[W][OA

    Science.gov (United States)

    Ruonala, Raili; Rinne, Päivi L.H.; Kangasjärvi, Jaakko; van der Schoot, Christiaan

    2008-01-01

    We investigated the short day (SD)–induced transition to dormancy in wild-type hybrid poplar (Populus tremula × P. tremuloides) and its absence in transgenic poplar overexpressing heterologous PHYTOCHROME A (PHYA). CENTRORADIALIS-LIKE1 (CENL1), a poplar ortholog of Arabidopsis thaliana TERMINAL FLOWER1 (TFL1), was markedly downregulated in the wild-type apex coincident with SD-induced growth cessation. By contrast, poplar overexpressing a heterologous Avena sativa PHYA construct (P35S:AsPHYA), with PHYA accumulating in the rib meristem (RM) and adjacent tissues but not in the shoot apical meristem (SAM), upregulated CENL1 in the RM area coincident with an acceleration of stem elongation. In SD-exposed heterografts, both P35S:AsPHYA and wild-type scions ceased growth and formed buds, whereas only the wild type assumed dormancy and P35S:AsPHYA showed repetitive flushing. This shows that the transition is not dictated by leaf-produced signals but dependent on RM and SAM properties. In view of this, callose-enforced cell isolation in the SAM, associated with suspension of indeterminate growth during dormancy, may require downregulation of CENL1 in the RM. Accordingly, upregulation of CENL1/TFL1 might promote stem elongation in poplar as well as in Arabidopsis during bolting. Together, the results suggest that the RM is particularly sensitive to photoperiodic signals and that CENL1 in the RM influences transition to dormancy in hybrid poplar. PMID:18192437

  17. Impact of early season apical meristem injury by gall inducing tipworm (Diptera: Cecidomyiidae) on reproductive and vegetative growth of cranberry.

    Science.gov (United States)

    Tewari, S; Buonaccorsi, J P; Averill, A L

    2013-06-01

    Larvae of cranberry tipworm, Dasineura oxycoccana Johnson, disrupt early season growth of cranberry (Vaccinium macrocarpon Aiton) uprights or shoots by feeding on apical meristem tissue. A 2-yr field study was carried out at three different locations to determine the impact of tipworm feeding injury on the reproductive and vegetative growth of two cranberry cultivars ('Howes' and 'Stevens') in Massachusetts. In addition to tipworm-injured and intact control uprights, an artificial injury treatment simulating tipworm feeding was also included. Individual uprights of cranberry exhibited tolerance to natural (tipworm) and simulated apical meristem injury in the current growing season (fruit production) and results were corroborated by a greenhouse study. In the field study, weight of fruit was higher in tipworm-injured uprights as compared with intact control uprights at the sites with Howes. However, majority of injured uprights (tipworm and simulated) did not produce new growth from lateral buds (side-shoots) before the onset of dormancy. In the next growing season, fewer injured uprights resumed growth and produced flowers as compared with intact uprights at two of the three sites. We suggest that multiple-year studies focusing on whole plant response to tipworm herbivory will be required to determine the costs of chronic feeding injury over time.

  18. The iRoCS Toolbox--3D analysis of the plant root apical meristem at cellular resolution.

    Science.gov (United States)

    Schmidt, Thorsten; Pasternak, Taras; Liu, Kun; Blein, Thomas; Aubry-Hivet, Dorothée; Dovzhenko, Alexander; Duerr, Jasmin; Teale, William; Ditengou, Franck A; Burkhardt, Hans; Ronneberger, Olaf; Palme, Klaus

    2014-03-01

    To achieve a detailed understanding of processes in biological systems, cellular features must be quantified in the three-dimensional (3D) context of cells and organs. We described use of the intrinsic root coordinate system (iRoCS) as a reference model for the root apical meristem of plants. iRoCS enables direct and quantitative comparison between the root tips of plant populations at single-cell resolution. The iRoCS Toolbox automatically fits standardized coordinates to raw 3D image data. It detects nuclei or segments cells, automatically fits the coordinate system, and groups the nuclei/cells into the root's tissue layers. The division status of each nucleus may also be determined. The only manual step required is to mark the quiescent centre. All intermediate outputs may be refined if necessary. The ability to learn the visual appearance of nuclei by example allows the iRoCS Toolbox to be easily adapted to various phenotypes. The iRoCS Toolbox is provided as an open-source software package, licensed under the GNU General Public License, to make it accessible to a broad community. To demonstrate the power of the technique, we measured subtle changes in cell division patterns caused by modified auxin flux within the Arabidopsis thaliana root apical meristem. © 2014 The Authors The Plant Journal © 2014 John Wiley & Sons Ltd.

  19. Plant-specific Histone Deacetylases HDT½ Regulate GIBBERELLIN 2-OXIDASE 2 Expression to Control Arabidopsis Root Meristem Cell Number

    KAUST Repository

    Li, Huchen

    2017-08-31

    Root growth is modulated by environmental factors and depends on cell production in the root meristem (RM). New cells in the meristem are generated by stem cells and transit-amplifying cells, which together determine RM cell number. Transcription factors and chromatin-remodelling factors have been implicated in regulating the switch from stem cells to transit-amplifying cells. Here we show that two Arabidopsis thaliana paralogs encoding plant-specific histone deacetylases, HDT1 and HDT2, regulate a second switch from transit-amplifying cells to expanding cells. Knockdown of HDT½ (hdt1,2i) results in an earlier switch and causes a reduced RM cell number. Our data show that HDT½ negatively regulate the acetylation level of the C19-GIBBERELLIN 2-OXIDASE 2 (GA2ox2) locus and repress the expression of GA2ox2 in the RM and elongation zone. Overexpression of GA2ox2 in the RM phenocopies the hdt1,2i phenotype. Conversely, knockout of GA2ox2 partially rescues the root growth defect of hdt1,2i. These results suggest that by repressing the expression of GA2ox2, HDT½ likely fine-tune gibberellin metabolism and they are crucial for regulating the switch from cell division to expansion to determine RM cell number. We propose that HDT½ function as part of a mechanism that modulates root growth in response to environmental factors.

  20. Meristem maintenance, auxin, jasmonic and abscisic acid pathways as a mechanism for phenotypic plasticity in Antirrhinum majus

    Science.gov (United States)

    Weiss, Julia; Alcantud-Rodriguez, Raquel; Toksöz, Tugba; Egea-Cortines, Marcos

    2016-01-01

    Plants grow under climatic changing conditions that cause modifications in vegetative and reproductive development. The degree of changes in organ development i.e. its phenotypic plasticity seems to be determined by the organ identity and the type of environmental cue. We used intraspecific competition and found that Antirrhinum majus behaves as a decoupled species for lateral organ size and number. Crowding causes decreases in leaf size and increased leaf number whereas floral size is robust and floral number is reduced. Genes involved in shoot apical meristem maintenance like ROA and HIRZ, cell cycle (CYCD3a; CYCD3b, HISTONE H4) or organ polarity (GRAM) were not significantly downregulated under crowding conditions. A transcriptomic analysis of inflorescence meristems showed Gene Ontology enriched pathways upregulated including Jasmonic and Abscisic acid synthesis and or signalling. Genes involved in auxin synthesis such as AmTAR2 and signalling AmANT were not affected by crowding. In contrast, AmJAZ1, AmMYB21, AmOPCL1 and AmABA2 were significantly upregulated. Our work provides a mechanistic working hypothesis where a robust SAM and stable auxin signalling enables a homogeneous floral size while changes in JA and ABA signalling maybe responsible for the decreased leaf size and floral number.

  1. Investigation of protective effects of Erythrina velutina extract against MMS induced damages in the root meristem cells of Allium cepa

    Directory of Open Access Journals (Sweden)

    Deborah S. B. S. Silva

    2013-04-01

    Full Text Available Erythrina velutina Willd., Fabaceae, is a medicinal plant that can be found in the tropics and subtropics, including in the semi-arid northeastern Brazil. It is commonly used in folk medicine to treat anxiety, agitation and insomnia. E. velutina has been known to present analgesic, anti-inflammatory and antibacterial activities, however, it is unknown if this plant present a protective effect on DNA. We assessed the antigenotoxic effect of E. velutina against the genotoxic effects induced by MMS in the root meristem cells of Allium cepa. Three concentrations of the aqueous extract (100, 200 and 400 mg/L of this medicinal plant were used in three different types of treatment (pre-, post- and simultaneous. The effects of the extracts on the root meristem cells of A. cepa were analyzed at both macroscopic and microscopic levels. Protective effects were observed at higher concentrations in pre-treatment and in simultaneous treatment. The results suggest that E. velutina may present antigenotoxic properties and demonstrate its chemopreventive potential.

  2. Kip-related protein 3 is required for control of endoreduplication in the shoot apical meristem and leaves of Arabidopsis.

    Science.gov (United States)

    Jun, Sang Eun; Okushima, Yoko; Nam, Jaesung; Umeda, Masaaki; Kim, Gyung-Tae

    2013-01-01

    The cell cycle plays an important role in the development and adaptation of multicellular organisms; specifically, it allows them to optimally adjust their architecture in response to environmental changes. Kip-related proteins (KRPs) are important negative regulators of cyclin-dependent kinases (CDKs), which positively control the cell cycle during plant development. The Arabidopsis genome possesses seven KRP genes with low sequence similarity and distinct expression patterns; however, why Arabidopsis needs seven KRP genes and how these genes function in cell cycle regulation are unknown. Here, we focused on the characterization of KRP3, which was found to have unique functions in the shoot apical meristem (SAM) and leaves. KRP3 protein was localized to the SAM, including the ground meristem and vascular tissues in the ground part of the SAM and cotyledons. In addition, KRP3 protein was stabilized when treated with MG132, an inhibitor of the 26S proteasome, indicating that the protein may be regulated by 26S proteasome-mediated protein degradation. KRP3-overexpressing (KRP3 OE) transgenic plants showed reduced organ size, serrated leaves, and reduced fertility. Interestingly, the KRP3 OE transgenic plants showed a significant reduction in the size of the SAM with alterations in cell arrangement. In addition, compared to the wild type, the KRP3 OE transgenic plants had a higher DNA ploidy level in the SAM and leaves. Taken together, our data suggest that KRP3 plays important regulatory roles in the cell cycle and endoreduplication in the SAM and leaves.

  3. Cytokinin-Deficient Transgenic Arabidopsis Plants Show Multiple Developmental Alterations Indicating Opposite Functions of Cytokinins in the Regulation of Shoot and Root Meristem Activity

    Czech Academy of Sciences Publication Activity Database

    Werner, T.; Motyka, Václav; Laucou, V.; Smets, R.; Onckelen, H. V.; Schmülling, T.

    2003-01-01

    Roč. 15, č. 11 (2003), s. 2532-2550 ISSN 1040-4651 R&D Projects: GA AV ČR IAA6038002 Institutional research plan: CEZ:AV0Z5038910 Keywords : Transgenic Arabidopsis Plants * Cytokinins * Root Meristem Activity Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 10.679, year: 2003

  4. Revealing the importance of meristems and roots for the development of hypersensitive responses and full foliar resistance to Phytophthora infestans in the resistant potato cultivar Sarpo Mira

    DEFF Research Database (Denmark)

    Orlowska, Elzbieta Zofia; Basile, Alessio; Kandzia, Izabela

    2012-01-01

    The defence responses of potato against Phytophthora infestans were studied using the highly resistant Sarpo Mira cultivar. The effects of plant integrity, meristems, and roots on the hypersensitive response (HR), plant resistance, and the regulation of PR genes were analysed. Sarpo Mira shoots a...

  5. Centering the organizing center in the Arabidopsis thaliana shoot apical meristem by a combination of cytokinin signaling and self-organization

    NARCIS (Netherlands)

    Adibi, Milad; Yoshida, Saiko; Weijers, Dolf; Fleck, Christian

    2016-01-01

    Plants have the ability to continously generate new organs by maintaining populations of stem cells throught their lives. The shoot apical meristem (SAM) provides a stable environment for the maintenance of stem cells. All cells inside the SAM divide, yet boundaries and patterns are maintained.

  6. Ds tagging of BRANCHED FLORETLESS 1 (BFL1 that mediates the transition from spikelet to floret meristem in rice (Oryza sativa L

    Directory of Open Access Journals (Sweden)

    Hoque Mohammad

    2003-09-01

    Full Text Available Abstract Background The genetics of spikelet formation, a feature unique to grasses such as rice and maize, is yet to be fully understood, although a number of meristem and organ identity mutants have been isolated and investigated in Arabidopsis and maize. Using a two-element Ac/Ds transposon tagging system we have isolated a rice mutant, designated branched floretless 1 (bfl1 which is defective in the transition from spikelet meristem to floret meristem. Results The bfl1 mutant shows normal differentiation of the primary rachis-branches leading to initial spikelet meristem (bract-like structure equivalent to rudimentary glumes formation but fails to develop empty glumes and florets. Instead, axillary meristems in the bract-like structure produce sequential alternate branching, thus resulting in a coral shaped morphology of the branches in the developing panicle. The bfl1 mutant harbours a single Ds insertion in the upstream region of the BFL1 gene on chromosome 7 corresponding to PAC clone P0625E02 (GenBank Acc No. message URL http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=nucleotide&list_uids=34395191&dopt=GenBank&term=ap004570AP004570. RT-PCR analyses revealed a drastic reduction of BFL1 transcript levels in the bfl1 mutant compared to that in the wild-type. In each of the normal panicle-bearing progeny plants, from occasional revertant seeds of the vegetatively-propagated mutant plant, Ds was shown to be excised from the bfl1 locus. BFL1 contains an EREBP/AP2 domain and is most likely an ortholog of the maize transcription factor gene BRANCHED SILKLESS1 (BD1. Conclusions bfl1 is a Ds-tagged rice mutant defective in the transition from spikelet meristem (SM to floret meristem (FM. BFL1 is most probably a rice ortholog of the maize ERF (EREBP/AP2 transcription factor gene BD1. Based on the similarities in mutant phenotypes bfl1 is likely to be an allele of the previously reported frizzy panicle locus.

  7. Effects of N6-benzylaminopurine and Indole Acetic Acid on In Vitro Shoot Multiplication, Nodule-like Meristem Proliferation and Plant Regeneration of Malaysian Bananas (Musa spp.)

    Science.gov (United States)

    Sipen, Philip; Davey, Michael R

    2012-01-01

    Different concentrations of N6-benzylaminopurine (BAP) and indole acetic acid (IAA) in Murashige and Skoog based medium were assessed for their effects on shoot multiplication, nodule-like meristem proliferation and plant regeneration of the Malaysian banana cultivars Pisang Mas, Pisang Nangka, Pisang Berangan and Pisang Awak. BAP at 1–14 mg L−1 with or without 0.2 mg L−1 IAA, or BAP at 7–14 mg L−1 with the same concentration of IAA, was evaluated for shoot multiplication from shoot tips and the proliferation of nodule-like meristems from scalps, respectively. Plant regeneration from scalps was assessed using 1 mg L−1 BAP and 0.2 mg L−1 IAA separately, or a combination of these two growth regulators. Data on shoot multiplication, the proliferation of nodule-like meristems with associated plant regeneration were recorded after 30 days of culture. A maximum of 5 shoots per original shoot tip was achieved on medium supplemented with BAP at 5 mg L−1 (Pisang Nangka), 6 mg L−1 (Pisang Mas and Pisang Berangan), or 7 mg L−1 (Pisang Awak), with 0.2 mg L−1 IAA. BAP at 11 mg L−1 with 0.2 mg L−1 IAA induced the most highly proliferating nodule-like meristems in the four banana cultivars. Plant regeneration from scalps was optimum in all cases on medium containing 1 mg L−1 BAP and 0.2 mg L−1 IAA. This is the first report on the successful induction of highly proliferating nodule-like meristems and plant regeneration from scalps of the Malaysian banana cultivars Pisang Mas, Pisang Nangka, Pisang Berangan and Pisang Awak. PMID:24575235

  8. Dynamic expression reveals a two-step patterning of WUS and CLV3 during axillary shoot meristem formation in Arabidopsis.

    Science.gov (United States)

    Xin, Wei; Wang, Zhicai; Liang, Yan; Wang, Yonghong; Hu, Yuxin

    2017-07-01

    Seed plants have a remarkable capability to produce axillary meristems (AM) in the leaf axils, however, the dynamic establishment of a stem cell niche in AM is largely uncharacterized. We comprehensively examined the dynamic patterning of WUSCHEL (WUS) and CLAVATA3 (CLV3), the two key marker genes defining the shoot stem cell niches, during AM formation in Arabidopsis, and we found that a two-step patterning of WUS and CLV3 occurred during AM stem cell niche establishment. Our further work on the wus and clv3 mutants implicates that such two-step patterning is likely critical for the maintenance of AM progenitor cells and the specification of AM stem cell niche. These data provide a cytological frame for how a stem cell niche is established during AM formation. Copyright © 2017 Elsevier GmbH. All rights reserved.

  9. Lateral root initiation and formation within the parental root meristem of Cucurbita pepo: is auxin a key player?

    Science.gov (United States)

    Ilina, Elena L; Kiryushkin, Alexey S; Semenova, Victoria A; Demchenko, Nikolay P; Pawlowski, Katharina; Demchenko, Kirill N

    2018-04-19

    In some plant families, including Cucurbitaceae, initiation and development of lateral roots (LRs) occur in the parental root apical meristem. The objective of this study was to identify the general mechanisms underlying LR initiation (LRI). Therefore, the first cellular events leading to LRI as well as the role of auxin in this process were studied in the Cucurbita pepo root apical meristem. Transgenic hairy roots harbouring the auxin-responsive promoter DR5 fused to different reporter genes were used for visualizing of cellular auxin response maxima (ARMs) via confocal laser scanning microscopy and 3-D imaging. The effects of exogenous auxin and auxin transport inhibitors on root branching were analysed. The earliest LRI event involved a group of symmetric anticlinal divisions in pericycle cell files at a distance of 250-350 µm from the initial cells. The visualization of the ARMs enabled the precise detection of cells involved in determining the site of LR primordium formation. A local ARM appeared in sister cells of the pericycle and endodermis files before the first division. Cortical cells contributed to LR development after the anticlinal divisions in the pericycle via the formation of an ARM. Exogenous auxins did not increase the total number of LRs and did not affect the LRI index. Although exogenous auxin transport inhibitors acted in different ways, they all reduced the number of LRs formed. Literature data, as well as results obtained in this study, suggest that the formation of a local ARM before the first anticlinal formative divisions is the common mechanism underlying LRI in flowering plants. We propose that the mechanisms of the regulation of root branching are independent of the position of the LRI site relative to the parental root tip.

  10. Cytogenetic effects of commercial formulation of cypermethrin in root meristem cells of Allium sativum: spectroscopic basis of chromosome damage.

    Science.gov (United States)

    Saxena, P N; Chauhan, L K S; Gupta, S K

    2005-12-15

    To validate the use of Allium sativum as a sensitive test model for genotoxicity, the cytogenetic effects of a commercial formulation of the pyrethroid insecticide, cypermethrin, were evaluated in the root meristem cells of A. sativum. Ultraviolet (UV) and Fourier transform infrared (FTIR) spectral measurements were also carried out to understand the interaction of cypermethrin with DNA. In a preliminary toxicity assay, the EC50 for Allium root growth was estimated to be 8 ppm. For the cytogenetic assay, root meristem cells were exposed to 1, 2, 4, 8 and 16 ppm of the test compound for 24 h, and either processed immediately for analysis or incubated in water for 24 h of recovery and then processed. Cells analyzed immediately after the exposure had a significant, dose-dependent inhibition of mitotic index (MI) and induction of mitotic and chromosomal aberrations (MAs and CAs). The 24 h recovery period reduced the effect of the test compound on the MI and percent aberrations; however, cells exposed to 8 and 16 ppm showed a significant frequency of aberrations despite the recovery period. One part per million cypermethrin was consistently negative in the assay. The data indicate that higher doses of cypermethrin produce toxicity, CAs and MAs in A. sativum. The present study indicates that A. sativum is a sensitive and reliable test system. A bathochromic shift observed in UV absorption spectra reveals that cypermethrin binds with DNA. Role of vibrational modes of the active site in the recognition and reaction of cypermethrin with DNA has been discussed. Based on spectroscopic data and structural properties, a possible mechanism has been proposed for the interaction of cypermethrin with DNA resulting in chromosomal aberrations.

  11. Constitutive expression of the tzs gene from Agrobacterium tumefaciens virG mutant strains is responsible for improved transgenic plant regeneration in cotton meristem transformation.

    Science.gov (United States)

    Ye, Xudong; Chen, Yurong; Wan, Yuechun; Hong, Yun-Jeong; Ruebelt, Martin C; Gilbertson, Larry A

    2016-03-01

    KEY MESSAGE : virG mutant strains of a nopaline type of Agrobacterium tumefaciens increase the transformation frequency in cotton meristem transformation. Constitutive cytokinin expression from the tzs gene in the virG mutant strains is responsible for the improvement. Strains of Agrobacterium tumefaciens were tested for their ability to improve cotton meristem transformation frequency. Two disarmed A. tumefaciens nopaline strains with either a virGN54D constitutively active mutation or virGI77V hypersensitive induction mutation significantly increased the transformation frequency in a cotton meristem transformation system. The virG mutant strains resulted in greener explants after three days of co-culture in the presence of light, which could be attributed to a cytokinin effect of the mutants. A tzs knockout strain of virGI77V mutant showed more elongated, less green explants and decreased cotton transformation frequency, as compared to a wild type parental strain, suggesting that expression of the tzs gene is required for transformation frequency improvement in cotton meristem transformation. In vitro cytokinin levels in culture media were tenfold higher in the virGN54D strain, and approximately 30-fold higher in the virGI77V strain, in the absence of acetosyringone induction, compared to the wild type strain. The cytokinin level in the virGN54D strain is further increased upon acetosyringone induction, while the cytokinin level in the virGI77V mutant is decreased by induction, suggesting that different tzs gene expression regulation mechanisms are present in the two virG mutant strains. Based on these data, we suggest that the increased cytokinin levels play a major role in increasing Agrobacterium attachment and stimulating localized division of the attached plant cells.

  12. Reproductive failure in Arabidopsis thaliana under transient carbohydrate limitation: flowers and very young siliques are jettisoned and the meristem is maintained to allow successful resumption of reproductive growth.

    Science.gov (United States)

    Lauxmann, Martin A; Annunziata, Maria G; Brunoud, Géraldine; Wahl, Vanessa; Koczut, Andrzej; Burgos, Asdrubal; Olas, Justyna J; Maximova, Eugenia; Abel, Christin; Schlereth, Armin; Soja, Aleksandra M; Bläsing, Oliver E; Lunn, John E; Vernoux, Teva; Stitt, Mark

    2016-04-01

    The impact of transient carbon depletion on reproductive growth in Arabidopsis was investigated by transferring long-photoperiod-grown plants to continuous darkness and returning them to a light-dark cycle. After 2 days of darkness, carbon reserves were depleted in reproductive sinks, and RNA in situ hybridization of marker transcripts showed that carbon starvation responses had been initiated in the meristem, anthers and ovules. Dark treatments of 2 or more days resulted in a bare-segment phenotype on the floral stem, with 23-27 aborted siliques. These resulted from impaired growth of immature siliques and abortion of mature and immature flowers. Depolarization of PIN1 protein and increased DII-VENUS expression pointed to rapid collapse of auxin gradients in the meristem and inhibition of primordia initiation. After transfer back to a light-dark cycle, flowers appeared and formed viable siliques and seeds. A similar phenotype was seen after transfer to sub-compensation point irradiance or CO2 . It also appeared in a milder form after a moderate decrease in irradiance and developed spontaneously in short photoperiods. We conclude that Arabidopsis inhibits primordia initiation and aborts flowers and very young siliques in C-limited conditions. This curtails demand, safeguarding meristem function and allowing renewal of reproductive growth when carbon becomes available again. © 2015 John Wiley & Sons Ltd.

  13. Genotoxic Effects of Diuron Contaminated Soil on the Root Meristem Cells of Allium sativum: A Possible Mechanism of Chromosome Damage.

    Science.gov (United States)

    Saxena, P N; Chauhan, L K S; Chandra, Saurabh; Gupta, S K

    2004-01-01

    Diuron, a persistant substituted urea herbicide, was tested in the root meristem cells of Allium sativum for the possible cytogenetic effects and to compare the sensitivity with Allium cepa. Test concentrations of diuron 22.5, 45.0, and 90.0 ppm were mixed in soil and the cloves of A. sativum were placed over diuron-contaminated soils. Root meristematic cells were sampled at 48 h to score Mitotic/Chromosomal aberrations and to analyze the effect on mitotic index (MI). Microscopic analyses revealed significant and dose-dependent induction of mitotic as well as chromosomal breaks. The frequency of mitotic aberrations was every time found much higher than that of chromosomal aberrations. Mild percentage of Micronucleated and Binucleated cells was observed, as MI also declined during the analysis. Based on the data of valence charge densities on the atoms of herbicide molecule and spectroscopic studies, a possible mechanism of interaction of diuron with DNA molecule for chromosomal aberrations has been proposed.

  14. Use of embryogenic cell suspension and meristem-tip cultures for mutation breeding of apomictic Musa species

    International Nuclear Information System (INIS)

    Novak, F.J.; Afza, R.; Duren, M. van

    1990-01-01

    Full text: Breeding by crossing is difficult for banana and plantain. The plants are heterozygous, therefore mutagenic treatment may uncover a recessive allele by mutating or deleting a corresponding dominant allele. Meristem tips were excised from in vitro growing shoots and used for mutation experiments. Induction was carried out by irradiating shoot tips with γ rays and/or by treatment of explants with ethylmethanesulfonate (EMS). Cell suspension was initiated from corm and leaf tissue excised from in vitro grown plantlets. Mutagenised cell suspensions were derived from leaf and corm tissues irradiated with 60 Co γ rays - (10 to 60 Gy, 8 Gy/min). Musa clones exhibited differences in radiosensitivity and post-irradiation recovery. Doses of 20 to 40 Gy seem suitable for mutation induction. The EMS concentration of 25 mM for 4 hours was found effective for isolated shoot tips. Considerable phenotypic variation was observed among plants regenerated from in vitro shoot tips after mutagenic treatment. Leaf and corm explants kept their morphogenic ability in embryogenic cell suspensions after irradiation up to 25 Gy. (author)

  15. A plant U-box protein, PUB4, regulates asymmetric cell division and cell proliferation in the root meristem.

    Science.gov (United States)

    Kinoshita, Atsuko; ten Hove, Colette A; Tabata, Ryo; Yamada, Masashi; Shimizu, Noriko; Ishida, Takashi; Yamaguchi, Katsushi; Shigenobu, Shuji; Takebayashi, Yumiko; Iuchi, Satoshi; Kobayashi, Masatomo; Kurata, Tetsuya; Wada, Takuji; Seo, Mitsunori; Hasebe, Mitsuyasu; Blilou, Ikram; Fukuda, Hiroo; Scheres, Ben; Heidstra, Renze; Kamiya, Yuji; Sawa, Shinichiro

    2015-02-01

    The root meristem (RM) is a fundamental structure that is responsible for postembryonic root growth. The RM contains the quiescent center (QC), stem cells and frequently dividing meristematic cells, in which the timing and the frequency of cell division are tightly regulated. In Arabidopsis thaliana, several gain-of-function analyses have demonstrated that peptide ligands of the Clavata3 (CLV3)/embryo surrounding region-related (CLE) family are important for maintaining RM size. Here, we demonstrate that a plant U-box E3 ubiquitin ligase, PUB4, is a novel downstream component of CLV3/CLE signaling in the RM. Mutations in PUB4 reduced the inhibitory effect of exogenous CLV3/CLE peptide on root cell proliferation and columella stem cell maintenance. Moreover, pub4 mutants grown without exogenous CLV3/CLE peptide exhibited characteristic phenotypes in the RM, such as enhanced root growth, increased number of cortex/endodermis stem cells and decreased number of columella layers. Our phenotypic and gene expression analyses indicated that PUB4 promotes expression of a cell cycle regulatory gene, CYCD6;1, and regulates formative periclinal asymmetric cell divisions in endodermis and cortex/endodermis initial daughters. These data suggest that PUB4 functions as a global regulator of cell proliferation and the timing of asymmetric cell division that are important for final root architecture. © 2015. Published by The Company of Biologists Ltd.

  16. AGO6 functions in RNA-mediated transcriptional gene silencing in shoot and root meristems in Arabidopsis thaliana.

    Directory of Open Access Journals (Sweden)

    Changho Eun

    Full Text Available RNA-directed DNA methylation (RdDM is a small interfering RNA (siRNA-mediated epigenetic modification that contributes to transposon silencing in plants. RdDM requires a complex transcriptional machinery that includes specialized RNA polymerases, named Pol IV and Pol V, as well as chromatin remodelling proteins, transcription factors, RNA binding proteins, and other plant-specific proteins whose functions are not yet clarified. In Arabidopsis thaliana, DICER-LIKE3 and members of the ARGONAUTE4 group of ARGONAUTE (AGO proteins are involved, respectively, in generating and using 24-nt siRNAs that trigger methylation and transcriptional gene silencing of homologous promoter sequences. AGO4 is the main AGO protein implicated in the RdDM pathway. Here we report the identification of the related AGO6 in a forward genetic screen for mutants defective in RdDM and transcriptional gene silencing in shoot and root apical meristems in Arabidopsis thaliana. The identification of AGO6, and not AGO4, in our screen is consistent with the primary expression of AGO6 in shoot and root growing points.

  17. Molecular cloning, phylogenetic analysis, and expression patterns of LATERAL SUPPRESSOR-LIKE and REGULATOR OF AXILLARY MERISTEM FORMATION-LIKE genes in sunflower (Helianthus annuus L.).

    Science.gov (United States)

    Fambrini, Marco; Salvini, Mariangela; Pugliesi, Claudio

    2017-03-01

    The wild sunflower (Helianthus annuus) plants develop a highly branched form with numerous small flowering heads. The origin of a no branched sunflower, producing a single large head, has been a key event in the domestication process of this species. The interaction between hormonal factors and several genes organizes the initiation and outgrowth of axillary meristems (AMs). From sunflower, we have isolated two genes putatively involved in this process, LATERAL SUPPRESSOR (LS)-LIKE (Ha-LSL) and REGULATOR OF AXILLARY MERISTEM FORMATION (ROX)-LIKE (Ha-ROXL), encoding for a GRAS and a bHLH transcription factor (TF), respectively. Typical amino acid residues and phylogenetic analyses suggest that Ha-LSL and Ha-ROXL are the orthologs of the branching regulator LS and ROX/LAX1, involved in the growth habit of both dicot and monocot species. qRT-PCR analyses revealed a high accumulation of Ha-LSL transcripts in roots, vegetative shoots, and inflorescence shoots. By contrast, in internodal stems and young leaves, a lower amount of Ha-LSL transcripts was observed. A comparison of transcription patterns between Ha-LSL and Ha-ROXL revealed some analogies but also remarkable differences; in fact, the gene Ha-ROXL displayed a low expression level in all organs analyzed. In situ hybridization (ISH) analysis showed that Ha-ROXL transcription was strongly restricted to a small domain within the boundary zone separating the shoot apical meristem (SAM) and the leaf primordia and in restricted regions of the inflorescence meristem, beforehand the separation of floral bracts from disc flower primordia. These results suggested that Ha-ROXL may be involved to establish a cell niche for the initiation of AMs as well as flower primordia. The accumulation of Ha-LSL transcripts was not restricted to the boundary zones in vegetative and inflorescence shoots, but the mRNA activity was expanded in other cellular domains of primary shoot apical meristem as well as AMs. In addition, Ha

  18. Analysis of the Arabidopsis superman allelic series and the interactions with other genes demonstrate developmental robustness and joint specification of male–female boundary, flower meristem termination and carpel compartmentalization

    Science.gov (United States)

    Breuil-Broyer, Stéphanie; Trehin, Christophe; Morel, Patrice; Boltz, Véronique; Sun, Bo; Chambrier, Pierre; Ito, Toshiro; Negrutiu, Ioan

    2016-01-01

    Background and Aims SUPERMAN is a cadastral gene controlling the sexual boundary in the flower. The gene’s functions and role in flower development and evolution have remained elusive. The analysis of a contrasting SUP allelic series (for which the names superman, superwoman and supersex have been coined) makes it possible to distinguish early vs. late regulatory processes at the flower meristem centre to which SUP is an important contributor. Their understanding is essential in further addressing evolutionary questions linking bisexuality and flower meristem homeostasis. Methods Inter-allelic comparisons were carried out and SUP interactions with other boundary factors and flower meristem patterning and homeostasis regulators (such as CLV, WUS, PAN, CUC, KNU, AG, AP3/PI, CRC and SPT) have been evaluated at genetic, molecular, morphological and histological levels. Key Results Early SUP functions include mechanisms of male–female (sexual) boundary specification, flower mersitem termination and control of stamen number. A SUP-dependent flower meristem termination pathway is identified and analysed. Late SUP functions play a role in organ morphogenesis by controlling intra-whorl organ separation and carpel medial region formation. By integrating early and late SUP functions, and by analyzing in one single experiment a series of SUP genetic interactions, the concept of meristematic ‘transference’ (cascade) – a regulatory bridging process redundantly and sequentially co-ordinating the triggering and completion of flower meristem termination, and carpel margin meristem and placenta patterning – is proposed. Conclusions Taken together, the results strongly support the view that SUP(-type) function(s) have been instrumental in resolving male/female gradients into sharp male and female identities (whorls, organs) and in enforcing flower homeostasis during evolution. This has probably been achieved by incorporating the meristem patterning system of the floral

  19. Analysis of the Arabidopsis superman allelic series and the interactions with other genes demonstrate developmental robustness and joint specification of male-female boundary, flower meristem termination and carpel compartmentalization.

    Science.gov (United States)

    Breuil-Broyer, Stéphanie; Trehin, Christophe; Morel, Patrice; Boltz, Véronique; Sun, Bo; Chambrier, Pierre; Ito, Toshiro; Negrutiu, Ioan

    2016-04-01

    SUPERMAN is a cadastral gene controlling the sexual boundary in the flower. The gene's functions and role in flower development and evolution have remained elusive. The analysis of a contrasting SUP allelic series (for which the names superman, superwoman and supersex have been coined) makes it possible to distinguish early vs. late regulatory processes at the flower meristem centre to which SUP is an important contributor. Their understanding is essential in further addressing evolutionary questions linking bisexuality and flower meristem homeostasis. Inter-allelic comparisons were carried out and SUP interactions with other boundary factors and flower meristem patterning and homeostasis regulators (such as CLV, WUS, PAN, CUC, KNU, AG, AP3/PI, CRC and SPT) have been evaluated at genetic, molecular, morphological and histological levels. Early SUP functions include mechanisms of male-female (sexual) boundary specification, flower mersitem termination and control of stamen number. A SUP-dependent flower meristem termination pathway is identified and analysed. Late SUP functions play a role in organ morphogenesis by controlling intra-whorl organ separation and carpel medial region formation. By integrating early and late SUP functions, and by analyzing in one single experiment a series of SUP genetic interactions, the concept of meristematic 'transference' (cascade) - a regulatory bridging process redundantly and sequentially co-ordinating the triggering and completion of flower meristem termination, and carpel margin meristem and placenta patterning - is proposed. Taken together, the results strongly support the view that SUP(-type) function(s) have been instrumental in resolving male/female gradients into sharp male and female identities (whorls, organs) and in enforcing flower homeostasis during evolution. This has probably been achieved by incorporating the meristem patterning system of the floral axis into the female/carpel programme. © The Author 2016

  20. Recessive antimorphic alleles overcome functionally redundant loci to reveal TSO1 function in Arabidopsis flowers and meristems.

    Directory of Open Access Journals (Sweden)

    Paja Sijacic

    2011-11-01

    Full Text Available Arabidopsis TSO1 encodes a protein with conserved CXC domains known to bind DNA and is homologous to animal proteins that function in chromatin complexes. tso1 mutants fall into two classes due to their distinct phenotypes. Class I, represented by two different missense mutations in the CXC domain, leads to failure in floral organ development, sterility, and fasciated inflorescence meristems. Class II, represented by a nonsense mutation and a T-DNA insertion line, develops wild-type-like flowers and inflorescences but shows severely reduced fertility. The phenotypic variability of tso1 alleles presents challenges in determining the true function of TSO1. In this study, we use artificial microRNA, double mutant analysis, and bimolecular fluorescence complementation assay to investigate the molecular basis underlying these two distinct classes of phenotypes. We show that the class I mutants could be converted into class II by artificial microRNA knockdown of the tso1 mutant transcript, suggesting that class I alleles produce antimorphic mutant proteins that interfere with functionally redundant loci. We identified one such redundant factor coded by the closely related TSO1 homolog SOL2. We show that the class I phenotype can be mimicked by knocking out both TSO1 and its homolog SOL2 in double mutants. Such antimorphic alleles targeting redundant factors are likely prevalent in Arabidopsis and maybe common in organisms with many sets of paralogous genes such as human. Our data challenge the conventional view that recessive alleles are always hypomorphic or null and that antimorphic alleles are always dominant. This study shows that recessive alleles can also be antimorphic and can produce a phenotype more severe than null by interfering with the function of related loci. This finding adds a new paradigm to classical genetic concepts, with important implications for future genetic studies both in basic research as well as in agriculture and medicine.

  1. Auxin-cytokinin synergism in vitro for producing genetically stable plants of Ruta graveolens using shoot tip meristems

    Directory of Open Access Journals (Sweden)

    Mohammad Faisal

    2018-02-01

    Full Text Available An efficient micropropagation protocol was developed for Ruta graveolens Linn. using shoot tip meristems derived from a 4-month-old field grown plant. In vitro shoot regeneration and proliferation was accomplished on Murashige and Skoogs (MS semi-solid medium in addition to different doses of cytokinins viz.6- benzyl adenine (BA, Kinetin (Kn or 2-isopetynyl adenine (2iP, singly or in combination with auxins viz. indole-3-acetic acid (IAA, indole-3-butyric acid (IBA or α-naphthalene acetic acid (NAA. Highest regeneration frequency (27.6% was obtained on (MS medium composed of BA (10 µM with maximum number (9.4 of shoots and 4.3 cm shoot length after 4 weeks of incubation. Among various combinations tried best regeneration frequency (71% of multiple shoot formation with highest number (12.6 of shoots per shoot tip explants were achieved in MS medium augmented with a combination BA (10.0 µM and NAA (2.5 µM after 4 weeks of incubation. The optimum frequency (97% of rhizogenesis was achieved on half-strength MS medium having 0.5 µM IBA after 4 weeks of incubation. Tissue culture raised plantlets with 5–7 fully opened leaves with healthy root system were successfully acclimatized off in Soilrite™ with 80% survival rate followed by transportation to normal soil under natural light. Genetic stability among in vitro raised progeny was evaluated by ISSR and RAPD markers. The entire banding pattern revealed from in vitro regenerated plants was monomorphic to the donor. The present protocol provides an alternative option for commercial propagation and fruitful setting up of genetically uniform progeny for sustainable utilization and germplasm preservation.

  2. Repression of Lateral Organ Boundary Genes by PENNYWISE and POUND-FOOLISH Is Essential for Meristem Maintenance and Flowering in Arabidopsis.

    Science.gov (United States)

    Khan, Madiha; Ragni, Laura; Tabb, Paul; Salasini, Brenda C; Chatfield, Steven; Datla, Raju; Lock, John; Kuai, Xiahezi; Després, Charles; Proveniers, Marcel; Yongguo, Cao; Xiang, Daoquan; Morin, Halima; Rullière, Jean-Pierre; Citerne, Sylvie; Hepworth, Shelley R; Pautot, Véronique

    2015-11-01

    In the model plant Arabidopsis (Arabidopsis thaliana), endogenous and environmental signals acting on the shoot apical meristem cause acquisition of inflorescence meristem fate. This results in changed patterns of aerial development seen as the transition from making leaves to the production of flowers separated by elongated internodes. Two related BEL1-like homeobox genes, PENNYWISE (PNY) and POUND-FOOLISH (PNF), fulfill this transition. Loss of function of these genes impairs stem cell maintenance and blocks internode elongation and flowering. We show here that pny pnf apices misexpress lateral organ boundary genes BLADE-ON-PETIOLE1/2 (BOP1/2) and KNOTTED-LIKE FROM ARABIDOPSIS THALIANA6 (KNAT6) together with ARABIDOPSIS THALIANA HOMEOBOX GENE1 (ATH1). Inactivation of genes in this module fully rescues pny pnf defects. We further show that BOP1 directly activates ATH1, whereas activation of KNAT6 is indirect. The pny pnf restoration correlates with renewed accumulation of transcripts conferring floral meristem identity, including FD, SQUAMOSA PROMOTER-BINDING PROTEIN LIKE genes, LEAFY, and APETALA1. To gain insight into how this module blocks flowering, we analyzed the transcriptome of BOP1-overexpressing plants. Our data suggest a central role for the microRNA156-SQUAMOSA PROMOTER BINDING PROTEIN-LIKE-microRNA172 module in integrating stress signals conferred in part by promotion of jasmonic acid biosynthesis. These data reveal a potential mechanism by which repression of lateral organ boundary genes by PNY-PNF is essential for flowering. © 2015 American Society of Plant Biologists. All Rights Reserved.

  3. Establecimiento y multiplicación in vitro de mora de castilla (Rubus glaucus Benth. variedad sin espinas, mediante ápices meristemáticos

    Directory of Open Access Journals (Sweden)

    Sigarroa Rieche Alina Katil

    2011-12-01

    Full Text Available Se evaluó una técnica de micropropagación de plantas de mora (Rubus glaucus de la variedad sin espinas, a partir de ápices meristemáticos. En la fase de establecimiento se evaluó un protocolo de desinfección utilizando por 5 min solución de jabón detergente comercial y agua + alcohol 70% por 2 min + hipoclorito 3% con dos tiempos de exposición diferentes: T1 por 5 min y T2 por 10 min. Después de desinfectar las microestacas se extrajeron los ápices meristemáticos y se establecieron in vitro bajo un diseño completamente al azar para evaluar dos medios de cultivo: M1 y M2. A partir de las plántulas desarrolladas se efectuó la multiplicación en los medios de cultivo M1, M3 y M4. Ambos tratamientos de desinfección resultaron efectivos alcanzando 100% de desinfección de los explantes con cada uno de ellos. La siembra de ápices meristemáticos permitió el establecimiento de cultivos asépticos y un adecuado desarrollo de los explantes después de seis semanas de cultivo, con prendimiento de 83.4% para M1 y 66.6% para M2. El análisis de varianza (Anova y la prueba de rangos múltiples mostraron que la multiplicación fue mejor en el medio M1 con una mayor tasa de crecimiento y desarrollo del explante, al obtener coeficientes de multiplicación de 7.5 brotes/plántula y una altura promedio de 1.95 cm.

  4. From shoot to leaf: step-wise shifts in meristem and KNOX1 activity correlate with the evolution of a unifoliate body plan in Gesneriaceae.

    Science.gov (United States)

    Nishii, Kanae; Huang, Bing-Hong; Wang, Chun-Neng; Möller, Michael

    2017-01-01

    Typical dicots possess equal-sized cotyledons and leaf-bearing shoots topped with a shoot apical meristem (SAM), the source of lateral organs, and where KNOX1 homeobox genes act as key regulators. New World Gesneriaceae show typical cotyledons, whereas Old World Gesneriaceae show anisocotyly, the unequal post-germination growth of cotyledons, and include unifoliate (one-leaf) plants. One-leaf plants show an extremely reduced body plan: the adult above-ground photosynthetic tissue consisting of a single cotyledon, a macrocotyledon enlarged by the basal meristem (BM), but lacking a SAM. To investigate the origin and evolution of the BM and one-leaf plants, the meristem activity and KNOX1 SHOOTMERISTEMLESS (STM) expression in cotyledons and leaves were systematically studied by RT-PCR and in situ hybridization across the family Gesneriaceae, Jovellana in Calceolariaceae (sister family to Gesneriaceae), and Antirrhinum in Plantaginaceae, all families of order Lamiales (asterids), in comparison to Arabidopsis (Brassicales, rosids). In all examined Lamiales samples, unlike Arabidopsis, BM activity accompanied by STM expression was found in both cotyledons in early stages. Foliage leaves of Gesneriaceae and Jovellana also showed the correlation of BM and STM expression. An extension of BM activity was found following a phylogenetic trajectory towards one-leaf plants where it is active throughout the lifetime of the macrocotyledon. Our results suggest that KNOX1 involvement in early cotyledon expansion originated early on in the diversification of Lamiales and is proposed as the prerequisite for the evolution of vegetative diversity in Gesneriaceae. Step-wise morphological shifts, driven by transfers of meristematic activity, as evidenced by shifts in KNOX1 expression, may be one mechanism by which morphological diversity evolves in plants.

  5. Differential spatial expression of A- and B-type CDKs, and distribution of auxins and cytokinins in the open transverse root apical meristem of Cucurbita maxima.

    Science.gov (United States)

    Chiappetta, Adriana; Bruno, Leonardo; Salimonti, Amelia; Muto, Antonella; Jones, Jessica; Rogers, Hilary J; Francis, Dennis; Bitonti, Maria Beatrice

    2011-05-01

    Aside from those on Arabidopsis, very few studies have focused on spatial expression of cyclin-dependent kinases (CDKs) in root apical meristems (RAMs), and, indeed, none has been undertaken for open meristems. The extent of interfacing between cell cycle genes and plant growth regulators is also an increasingly important issue in plant cell cycle studies. Here spatial expression/localization of an A-type and B-type CDK, auxin and cytokinins are reported in relation to the hitherto unexplored anatomy of RAMs of Cucurbita maxima. Median longitudinal sections were cut from 1-cm-long primary root tips of C. maxima. Full-length A-type CDKs and a B-type CDK were cloned from C. maxima using degenerate primers, probes of which were localized on sections of RAMs using in situ hybridization. Isopentenyladenine (iPA), trans-zeatin (t-Z) and indole-3yl-acetic acid (IAA) were identified on sections by immunolocalization. The C. cucurbita RAM conformed to an open transverse (OT) meristem typified by an absence of a clear boundary between the eumeristem and root cap columella, but with a distinctive longitudinally thickened epidermis. Cucma;CDKA;1 expression was detected strongly in the longitudinally thickened epidermis, a tissue with mitotic competence that contributes cells radially to the root cap of OT meristems. Cucma;CDKB2 was expressed mainly in proliferative regions of the RAM and in lateral root primordia. iPA and t-Z were mainly distributed in differentiated cells whilst IAA was distributed more uniformly in all tissues of the RAM. Cucma;CDKA;1 was expressed most strongly in cells that have proliferative competence whereas Cucma;CDKB2 was confined mainly to mitotic cells. iPA and t-Z marked differentiated cells in the RAM, consistent with the known effect of cytokinins in promoting differentiation in root systems. iPA/t-Z were distributed in a converse pattern to Cucma;CDKB2 expression whereas IAA was detected in most cells in the RAM regardless of their proliferative

  6. Depletion of cellular brassinolide decreases embryo production and disrupts the architecture of the apical meristems in Brassica napus microspore-derived embryos.

    Science.gov (United States)

    Belmonte, Mark; Elhiti, Mohamed; Waldner, Blaine; Stasolla, Claudio

    2010-06-01

    Exogenous applications of brassinolide (BL) increased the number and quality of microspore-derived embryos (MDEs) whereas treatments with brassinazole (BrZ), a BL biosynthetic inhibitor, had the opposite effect. At the optimal concentration (4x10(-6) M) BrZ decreased both embryo yield and conversion to less than half the value of control embryos. Metabolic studies revealed that BL levels had profound effects on glutathione and ascorbate metabolism by altering the amounts of their reduced forms (ASC and GSH) and oxidized forms [dehydroascorbate (DHA), ascorbate free radicals (AFRs), and GSSG]. Applications of BL switched the glutathione and ascorbate pools towards the oxidized forms, thereby lowering the ASC/ASC+DHA+AFR and GSH/GSH+GSSG ratios. These changes were ascribed to the ability of BL to increase the activity of ascorbate peroxidase (APX) and decrease that of glutathione reductase (GR). This trend was reversed in a BL-depleted environment, effected by BrZ applications. These metabolic alterations were associated with changes in embryo structure and performance. BL-treated MDEs developed zygotic-like shoot apical meristems (SAMs) whereas embryos treated with BrZ developed abnormal meristems. In the presence of BrZ, embryos either lacked a visible SAM, or formed SAMs in which the meristematic cells showed signs of differentiation, such as vacuolation and storage product accumulation. These abnormalities were accompanied by the lack or misexpression of three meristem marker genes isolated from Brassica napus (denoted as BnSTM, BnCLV1, and BnZLL-1) homologous to the Arabidopsis SHOOTMERISTEMLESS (STM), CLAVATA 1 (CLV1), and ZWILLE (ZLL). The expression of BnSTM and BnCLV1 increased after a few days in cultures in embryos treated with BL whereas an opposite tendency was observed with applications of BrZ. Compared with control embryos where these two genes exhibited abnormal localization patterns, BnSTM and BnCLV1 always localized throughout the subapical domains

  7. Transient decreases in methylation at 5'-cCGG-3' sequences in potato (Solanum tuberosum L.) meristem DNA during progression of tubers through dormancy precede the resumption of sprout growth.

    Science.gov (United States)

    Law, R David; Suttle, Jeffrey C

    2003-02-01

    The 5-methylcytosine (5mC) content in DNA of tuber meristems isolated from field-grown potatoes (Solanum tuberosum L.) was determined during a 7-month storage period at 3 degrees C for three growing/postharvest seasons. No significant changes in 5mC levels were noted genome-wide or within 5'-CG-3' dinucleotide sequences, 5'-CG-3' islands or 5'-CA(T)G-3' trinucleotide sequences during storage. However, a consistent but transient 50-70% decrease in methylation at both cytosines within 5'-CCGG-3' sequences was detected that peaked 112-194 days after harvest. This result was corroborated by methylation-sensitive amplified fragment length polymorphism analysis of meristem DNA. Similar to tuber meristems undergoing progression through natural dormancy, premature chemical termination of dormancy resulted in rapid, transient 5'-CCGG-3' demethylation in meristem DNA. Minimum methylation levels at this sequence preceded initiation of high levels of de novo DNA synthesis by two days. Cytosine methylation status was also followed in in vitro-generated potato microtubers during 7 months of post-harvest storage. As in DNA from tuber bud meristems, no changes in genome-wide 5mC content or methylation at 5'-CA(T)G-3' or 5'-CG-3' island sequences were noted in microtuber DNA. However, there was a transient 46% drop in methylation at 5'-CG-3' dinucleotides concomitant with minimum levels of 5'-CCGG-3' methylation (30-60% below those in dormant microtubers) 57-98 days after harvest. As microtubers exited dormancy, there were sustained three- and seven-fold increases in RNA and DNA synthesis rates, peaking on or after 98 days of storage, respectively. Together, these data demonstrate that demethylation of 5'-CCGG-3' sequences occurs independently of tuber age during dormancy progression and precedes transcriptional activation of genes leading to cell division and meristem growth in potatoes.

  8. Screening for sweet potato (Ipomoea batatas (L.)) viruses and their elimination using thermotheraphy-meristem tip culture technique

    International Nuclear Information System (INIS)

    Arkorful, E.

    2012-11-01

    Despite its high potential for food security, production of sweet potato is constrained by viruses which reduce yield by 90%. It is therefore essential to screen for, identify and eliminate these viruses in elite clones before dissemination to farmers. In this study, visual symptomatology and PCR-based techniques were used to identify sweet potato viruses. Visual symptomatology revealed virus associated symptoms ranging from vein clearing, interveinal chlorosis, chlorotic spots, upward curling on leaf edges, leaf narrowing and distortion, purpling, blistering, reduction of the leaf blades and general leaf yellowing in all 22 accessions grown on the field. Disease Incidence (DI) significantly (p≤0.05) varied between accessions with US003 having the lowest (20%) while ten accessions had 90% DI at the end of the study. Index of symptom severity of all plants (ISSap) ranged from 1.08±0.09 to 3.67 ±0.11 with VOTCR003 having the lowest suggesting that it is a moderately susceptible accession while VOTCR002 had the highest suggesting that it is susceptible to viral diseases. Contrarily, index of symptom severity of diseased plants (ISSdp) ranged from 2.00±0.25 to 3.75±0.32. The accession VOTCR002 had the highest ISSdp. Visual symptomatology showed that VOTCR002 had the highest DI, ISSap and ISSdp suggesting that it is highly susceptible to viral diseases. Ten severely infected accessions were tested for Sweet Potato leaf curl virus (SPLCV), Sweet Potato chlorotic stunt virus (SPCSV), Sweet potato feathery mottle virus (SPFMV) and Sweet Potato mild mottle virus (SPMMV) using PCR and RT-PCR techniques. RT-PCR did not amplify any of the virus genomes due to prolonged storage enzymes, In contrast, PCR detected SPLCV in 30% of the accessions. Plants infected with SPLCV were grown in the chamber at 35 degrees celsius for 4 weeks followed by meristem top culture. The regenerants were indexed after ten weeks for SPLCV. Fifty two percent (52.385 od the regenerants were

  9. Zastosowanie peptonu Peptobak-Bacutil tu hodowli merystematycznej tkanki Cymbidium Sw. [Application of the peptone Peptobak-Bacutil medium in the culture of meristem-tissue of Cymbidium Sw.

    Directory of Open Access Journals (Sweden)

    K. Kukułczanka

    2015-06-01

    Full Text Available In was found that peptone of Peptobak-Bacutil brand (produced in Poland fulfills perfectly the requirements in cultures in vitro of the meristem tissues of Cymbidium in the modified Tsuchiya's medium in a concentration of 2 g per 1. A decrease in the concentration to 1 g per 1. affects the growth intensity of the tissue, but an increase of concentration up to 3 g per 1. retards the transformation of protocorms into the plant-stage. Growth of the meristem tissue of Cymbidium in the medium consolidated with agar is weaker and the number of protocorms produced 2,3 times lower than in liquid media.

  10. Genome-wide allele-specific expression analysis using Massively Parallel Signature Sequencing (MPSS) reveals cis- and trans-effects on gene expression in maize hybrid meristem tissue.

    Science.gov (United States)

    Guo, Mei; Yang, Sean; Rupe, Mary; Hu, Bin; Bickel, David R; Arthur, Lane; Smith, Oscar

    2008-03-01

    Allelic differences in expression are important genetic factors contributing to quantitative trait variation in various organisms. However, the extent of genome-wide allele-specific expression by different modes of gene regulation has not been well characterized in plants. In this study we developed a new methodology for allele-specific expression analysis by applying Massively Parallel Signature Sequencing (MPSS), an open ended and sequencing based mRNA profiling technology. This methodology enabled a genome-wide evaluation of cis- and trans-effects on allelic expression in six meristem stages of the maize hybrid. Summarization of data from nearly 400 pairs of MPSS allelic signature tags showed that 60% of the genes in the hybrid meristems exhibited differential allelic expression. Because both alleles are subjected to the same trans-acting factors in the hybrid, the data suggest the abundance of cis-regulatory differences in the genome. Comparing the same allele expressed in the hybrid versus its inbred parents showed that 40% of the genes were differentially expressed, suggesting different trans-acting effects present in different genotypes. Such trans-acting effects may result in gene expression in the hybrid different from allelic additive expression. With this approach we quantified gene expression in the hybrid relative to its inbred parents at the allele-specific level. As compared to measuring total transcript levels, this study provides a new level of understanding of different modes of gene regulation in the hybrid and the molecular basis of heterosis.

  11. The concept of the eudicot shoot apical meristem as it applies to four Spiraea (Rosaceae), one Mentha (Lamiaceae) and one Euonymus (Celastraceae) cultivars based on chimeric analysis.

    Science.gov (United States)

    Korn, Robert W

    2013-05-01

    Eversporting eudicots were sought to see if they behave like gymnosperms. Behaviour of eversporting gymnosperm chimeras indicates a single apical cell is present in SAM and it would be of interest to see if eudicot chimeras have the same behaviour. Four eversporting spireas, the pineapple mint and the Silver King euonymus were inspected for the fate of the yellow (mutant)-green (wild type) chimeras. As with gymnosperms, unstable eudicot chimeras in the four spireas, the pineapple mint and the Silver King euonymus became stable yellow about 80 % or more of the time and 20 % or less became stable green. The statistically significant preponderance of chimeric fates becoming all yellow suggests that a single apical cell resides in the yellow tunica. As with gymnosperms, descendent cells of the yellow replacement corpus cell eventually take over the corpus. Here is the first chimeric set of data to support the hypothesis of a one-celled meristem in eudicots rather than the traditional view of a muticellular meristem.

  12. Expression of Arabidopsis class 1 phytoglobin (AtPgb1) delays death and degradation of the root apical meristem during severe PEG-induced water deficit.

    Science.gov (United States)

    Mira, Mohamed M; Huang, Shuanglong; Kapoor, Karuna; Hammond, Cassandra; Hill, Robert D; Stasolla, Claudio

    2017-11-28

    Maintenance of a functional root is fundamental to plant survival in response to some abiotic stresses, such as water deficit. In this study, we found that overexpression of Arabidopsis class 1 phytoglobin (AtPgb1) alleviated the growth retardation of polyethylene glycol (PEG)-induced water stress by reducing programmed cell death (PCD) associated with protein folding in the endoplasmic reticulum (ER). This was in contrast to PEG-stressed roots down-regulating AtPgb1 that exhibited extensive PCD and reduced expression of several attenuators of ER stress, including BAX Inhibitor-1 (BI-1). The death program experienced by the suppression of AtPgb1 in stressed roots was mediated by reactive oxygen species (ROS) and ethylene. Suppression of ROS synthesis or ethylene perception reduced PCD and partially restored root growth. The PEG-induced cessation of root growth was preceded by structural changes in the root apical meristem (RAM), including the loss of cell and tissue specification, possibly as a result of alterations in PIN1- and PIN4-mediated auxin accumulation at the root pole. These events were attenuated by the overexpression of AtPgb1 and aggravated when AtPgb1 was suppressed. Specifically, suppression of AtPgb1 compromised the functionality of the WOX5-expressing quiescent cells (QCs), leading to the early and premature differentiation of the adjacent columella stem cells and to a rapid reduction in meristem size. The expression and localization of other root domain markers, such as SCARECROW (SCR), which demarks the endodermis and QCs, and WEREWOLF (WER), which specifies the lateral root cap, were also most affected in PEG-treated roots with suppressed AtPgb1. Collectively, the results demonstrate that AtPgb1 exercises a protective role in roots exposed to lethal levels of PEG, and suggest a novel function of this gene in ensuring meristem functionality through the retention of cell fate specification. © The Author 2017. Published by Oxford University Press

  13. Dose rate, mitotic cycle duration, and sensitivity of cell transitions from G1 → S and G2 → M to protracted gamma radiation in root meristems

    International Nuclear Information System (INIS)

    Evans, L.S.; Hof, J.V.

    1975-01-01

    Experiments were designed to determine the relative radiosensitivity of the cell transition points of G1 → S and G2 → M in root meristems of several plant species. Label and mitotic indices and microspectrophotometry were used to measure the proportions of cells in each mitotic cycle stage in root meristems after protracted gamma radiation. The criterion of radiosensitivity was the dose rate needed to produce a tissue with less than 1 percent cells in S and none in M after 3 days of continuous exposure. The results show that DNA is the primary radiation target in proliferative root meristems and that the cycle duration stipulates the time interval of vulnerability. In each species, nonrandom reproducible cell proportions were established with 2C:4C:8C amounts of nuclear DNA after 3 days of exposure. Roots of Helianthus annuus, Crepis capillaris, and Tradescantia clone 02 had 80 percent cells with a 2C amount of DNA and 20 percent had a 4C amount of DNA. In these species the transition point of G1 → S was more radiosensitive than G2 → M. Roots of Pisum sativum and Triticum aestivum had cell proportions at 2C:4C:8C amounts of DNA in frequencies of 0.10 to 0.20:0.40 to 0.60:0.30 to 0.40. In these two species 0.30 to 0.40 cells underwent radiation-induced endoreduplication that resulted from a rapid inhibition of cell transit from G2 → M and a slower impairment of G1 → S. Cells increased from 2C to 4C and from 4C to 8C amounts of DNA during irradiation. The proportions of nuclei with 2C:4C:8C amounts of DNA were dependent in part upon the relative radiosensitivity of the G1 → S and G2 → M control points. The data show the relative radiosensitivity of the transition points from G1 → S and from G2 → M was species specific and unrelated to the cycle duration and mean nuclear DNA content of the plant species

  14. Involving undergraduates in the annotation and analysis of global gene expression studies: creation of a maize shoot apical meristem expression database.

    Science.gov (United States)

    Buckner, Brent; Beck, Jon; Browning, Kate; Fritz, Ashleigh; Grantham, Lisa; Hoxha, Eneda; Kamvar, Zhian; Lough, Ashley; Nikolova, Olga; Schnable, Patrick S; Scanlon, Michael J; Janick-Buckner, Diane

    2007-06-01

    Through a multi-university and interdisciplinary project we have involved undergraduate biology and computer science research students in the functional annotation of maize genes and the analysis of their microarray expression patterns. We have created a database to house the results of our functional annotation of >4400 genes identified as being differentially regulated in the maize shoot apical meristem (SAM). This database is located at http://sam.truman.edu and is now available for public use. The undergraduate students involved in constructing this unique SAM database received hands-on training in an intellectually challenging environment, which has prepared them for graduate and professional careers in biological sciences. We describe our experiences with this project as a model for effective research-based teaching of undergraduate biology and computer science students, as well as for a rich professional development experience for faculty at predominantly undergraduate institutions.

  15. Clastogenic adaption of Vicia faba root tip meristem cells after consecutive treatments with S-phase dependent and S-phase independent agents

    International Nuclear Information System (INIS)

    Heindorff, K.; Schubert, I.; Rieger, R.; Michaelis, A.

    1987-01-01

    Pretreatment of Vicia faba root tip meristems with low doses of S-phase independent clastogens, such as X-rays or bleomycin, prior to a high (challenge) dose of S-phase dependent clastogens, such as alkylating agents (TEM, Trenimon) or the pyridazine derivative MH, led to decreased challenge treatment-induced aberration frequencies, i.e., clastogenic adaptation. Using the inverse treatment sequence bleomycin and MH proved to be able to substitute for each other in provoking clastogenic (cross) adaptation while bleomycin and alkylating agents were unable to do so. The data support the assumption of inducible cellular functions that become triggered by low clastogen doses and additionally describe some particular properties of bleomycin when used for conditioning. Bleomycin proved to be capable to exert protection independent of the agent used for challenge treatment. (author)

  16. Assessment of genetic and epigenetic changes in virus-free garlic (Allium sativum L.) plants obtained by meristem culture followed by in vitro propagation.

    Science.gov (United States)

    Gimenez, Magalí Diana; Yañez-Santos, Anahí Mara; Paz, Rosalía Cristina; Quiroga, Mariana Paola; Marfil, Carlos Federico; Conci, Vilma Cecilia; García-Lampasona, Sandra Claudia

    2016-01-01

    This is the first report assessing epigenetic variation in garlic. High genetic and epigenetic polymorphism during in vitro culture was detected.Sequencing of MSAP fragments revealed homology with ESTs. Garlic (Allium sativum) is a worldwide crop of economic importance susceptible to viral infections that can cause significant yield losses. Meristem tissue culture is the most employed method to sanitize elite cultivars.Often the virus-free garlic plants obtained are multiplied in vitro (micro propagation). However, it was reported that micro-propagation frequently produces somaclonal variation at the phenotypic level, which is an undesirable trait when breeders are seeking to maintain varietal stability. We employed amplification fragment length polymorphism and methylation sensitive amplified polymorphism (MSAP) methodologies to assess genetic and epigenetic modifications in two culture systems: virus-free plants obtained by meristem culture followed by in vitro multiplication and field culture. Our results suggest that garlic exhibits genetic and epigenetic polymorphism under field growing conditions. However, during in vitro culture system both kinds of polymorphisms intensify indicating that this system induces somaclonal variation. Furthermore, while genetic changes accumulated along the time of in vitro culture, epigenetic polymorphism reached the major variation at 6 months and then stabilize, being demethylation and CG methylation the principal conversions.Cloning and sequencing differentially methylated MSAP fragments allowed us to identify coding and unknown sequences of A. sativum, including sequences belonging to LTR Gypsy retrotransposons. Together, our results highlight that main changes occur in the initial 6 months of micro propagation. For the best of our knowledge, this is the first report on epigenetic assessment in garlic.

  17. Floral Initiation in Response to Planting Date Reveals the Key Role of Floral Meristem Differentiation Prior to Budding in Canola (Brassica napus L.)

    Science.gov (United States)

    Zhang, Yaofeng; Zhang, Dongqing; Yu, Huasheng; Lin, Baogang; Fu, Ying; Hua, Shuijin

    2016-01-01

    In Brassica napus, floral development is a decisive factor in silique formation, and it is influenced by many cultivation practices including planting date. However, the effect of planting date on floral initiation in canola is poorly understood at present. A field experiment was conducted using a split plot design, in which three planting dates (early, 15 September, middle, 1 October, and late, 15 October) served as main plot and five varieties differing in maturity (1358, J22, Zhongshuang 11, Zheshuang 8, and Zheyou 50) employed as subplot. The purpose of this study was to shed light on the process of floral meristem (FM) differentiation, the influence of planting date on growth period (GP) and floral initiation, and silique formation. The main stages of FM developments can be divided into four stages: first, the transition from shoot apical meristem to FM; second, flower initiation; third, gynoecium and androecium differentiation; and fourth, bud formation. Our results showed that all genotypes had increased GPs from sowing to FM differentiation as planting date was delayed while the GPs from FM differentiation to budding varied year by year except the very early variety, 1358. Based on the number of flowers present at the different reproductive stages, the flowers produced from FM differentiation to budding closely approximated the final silique even though the FM differentiated continuously after budding and peaked generally at the middle flowering stage. The ratio of siliques to maximum flower number ranged from 48 to 80%. These results suggest that (1) the period from FM differentiation to budding is vital for effective flower and silique formation although there was no significant correlation between the length of the period and effective flowers and siliques, and (2) the increased number of flowers from budding were generally ineffective. Therefore, maximizing flower numbers prior to budding will improve silique numbers, and reducing FM degeneration should

  18. Injury to apical meristem of cranberry by Dasineura oxycoccana (Diptera: Cecidomyiidae) reduces production of floral-units in the next growing season.

    Science.gov (United States)

    Tewari, S; Buonaccorsi, J P; Averill, A L

    2012-08-01

    Cranberry tipworm, Dasineura oxycoccana Johnson (a gall-making fly), disrupts normal growth of cranberry (Vaccinium macrocarpon Aiton) by injuring the apical meristem of shoots or uprights. The impact of larval feeding injury on reproductive parameters of cranberry was determined, from one growing season to next, at upright (Maine and Massachusetts, 2008-2009) and plot levels (Massachusetts, 2009-2010 and 2010-2011). We also estimated the proportions of uprights injured because of tipworm feeding at several cranberry production sites (Massachusetts and Maine) and the proportions of uprights that produced flowers and fruits in the next growing season. Tipworm-injured uprights tagged at the end of the growing season did not produce floral-units (following year) across sites in both Massachusetts and Maine. There was significant variation among the sampled sites in the proportions of tipworm-injured uprights and also in the proportions of uprights with flowers in the next growing season (Massachusetts and Maine). A trend was apparent wherein sites with higher tipworm injury levels had relatively lower flowering proportions in the next growing season. However, sites in Massachusetts did not differ in the proportions of uprights that set fruit and in a replicated study, significant reduction in tipworm injury at plot level (using insecticide) did not impact flower and fruit production in the next growing season.

  19. A genetic screen for modifiers of UFO meristem activity identifies three novel FUSED FLORAL ORGANS genes required for early flower development in Arabidopsis.

    Science.gov (United States)

    Levin, J Z; Fletcher, J C; Chen, X; Meyerowitz, E M

    1998-06-01

    In a screen to identify novel genes required for early Arabidopsis flower development, we isolated four independent mutations that enhance the Ufo phenotype toward the production of filamentous structures in place of flowers. The mutants fall into three complementation groups, which we have termed FUSED FLORAL ORGANS (FFO) loci. ffo mutants have specific defects in floral organ separation and/or positioning; thus, the FFO genes identify components of a boundary formation mechanism(s) acting between developing floral organ primordia. FFO1 and FFO3 have specific functions in cauline leaf/stem separation and in first- and third-whorl floral organ separation, with FFO3 likely acting to establish and FFO1 to maintain floral organ boundaries. FFO2 acts at early floral stages to regulate floral organ number and positioning and to control organ separation within and between whorls. Plants doubly mutant for two ffo alleles display additive phenotypes, indicating that the FFO genes may act in separate pathways. Plants doubly mutant for an ffo gene and for ufo, lfy, or clv3 reveal that the FFO genes play roles related to those of UFO and LFY in floral meristem initiation and that FFO2 and FFO3 may act to control cell proliferation late in inflorescence development.

  20. Aberrant cell divisions in root meristeme of maize following exposure to X-rays low doses compared to similar effects of 50 Hz electromagnetic exposure

    Directory of Open Access Journals (Sweden)

    Luchian T.

    2012-04-01

    Full Text Available The response of maize to radiation exposure was investigated by two cytogenetic methods considering the importance of the geno-toxic effect for environmental and agricultural purposes. Uniform genophond seeds, freshly germinated, were exposed to relatively low radiation doses using a radiotherapy X-ray applicator from a hospital irradiation device and to a 50 Hz electromagnetic field with about 10 mT magnetic induction (generated within laboratory assembled electromagnetic coils. Radicular meristeme tissue aliquots were prevailed for cytogenetic investigation based on microscopic observations and cell counting. Microscope slides were prepared following a specific procedure (squash technique and Feulgen method based on modified Carr reactive coloration. Mitotic index as well as chromosomal aberration percentage were calculated for more than 30,000 cells taken into account. From a qualitative viewpoint, chromosomal aberrations such as interchromatidian bridges, lagging and expelled chromosomes and multipolar divisions were evidenced - no distinct situation for either ionizing radiation or electromagnetic field being identified. The main quantitative difference consisted in the increased mitotic index for electromagnetic exposure increased times compared with the diminished mitotic index in the case of low X-ray doses.

  1. Relationship between plant growth and cytological effect in root apical meristem after exposure of wheat dry seeds to carbon ion beams

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Qingfang [Radiobiology Laboratory, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, Gansu Province 730000 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Wang, Zhuanzi; Zhou, Libin; Qu, Ying; Lu, Dong [Radiobiology Laboratory, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, Gansu Province 730000 (China); Yu, Lixia; Du, Yan [Radiobiology Laboratory, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, Gansu Province 730000 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Jin, Wenjie [Radiobiology Laboratory, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, Gansu Province 730000 (China); Li, Wenjian, E-mail: wjli@impcas.ac.cn [Radiobiology Laboratory, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, Gansu Province 730000 (China)

    2013-06-15

    In order to analyze the relationship between plant growth and cytological effects, wheat dry seeds were exposed to various doses of {sup 12}C{sup 6+} beams and the biological endpoints reflecting plant growth and root apical meristem (RAM) activities were investigated. The results showed that most of the seeds were able to germinate normally within all dose range, while the plant survival rate descended at higher doses. The seedling growth including root length and seedling height also decreased significantly at higher doses. Mitotic index (MI) in RAM had no changes at 10 and 20 Gy and decreased obviously at higher doses and the proportion of prophase cells had the same trend with MI. These data suggested that RAM cells experienced cell cycle arrest, which should be responsible for the inhibition of root growth after exposure to higher doses irradiation. Moreover, various types of chromosome aberrations (CAs) were observed in the mitotic cells. The frequencies of mitotic cells with lagging chromosomes and these with anaphase bridges peaked around 60 Gy, while the frequencies of these with fragments increased as the irradiation doses increased up to 200 Gy. The total frequencies of mitotic cells with CAs induced by irradiation increased significantly with the increasing doses. The serious damage of mitotic chromosomes maybe caused cell cycle arrest or cell death. These findings suggested that the influences of {sup 12}C{sup 6+} beams irradiation on plant growth were related to the alternation of mitotic activities and the chromosomal damages in RAM.

  2. Low- and High-Temperature Tolerance and Acclimation for Chlorenchyma versus Meristem of the Cultivated Cacti Nopalea cochenillifera, Opuntia robusta, and Selenicereus megalanthus

    Directory of Open Access Journals (Sweden)

    Brian R. Zutta

    2011-01-01

    Full Text Available Dividing meristematic cells are thought to be more sensitive to extreme temperatures compared to other tissues, such as chlorenchyma. This was examined for low and high temperatures for three widely cultivated cacti: Nopalea cochenillifera, Opuntia robusta, and Selenicereus megalanthus. Temperature tolerances of chlorenchyma and meristem were based on the cellular uptake of the vital stain neutral red for plants at mean day/night air temperatures of 25/20°C and plants maintained at 10/5°C or 45/40°C to examine temperature acclimation. Meristematic cells tolerated 1.8°C lower low temperatures and 4.0°C higher high temperatures than chlorenchyma cells for the three species at 25/20°C. Both tissue types showed acclimation, with a decrease or increase in temperature tolerated at 10/5°C or 45/40°C, respectively. Meristematic cells were more tolerant of extreme temperatures compared to chlorenchyma, contrary to the prevailing belief, and may reflect an additional strategy for cacti to survive extreme temperatures.

  3. Relationship between plant growth and cytological effect in root apical meristem after exposure of wheat dry seeds to carbon ion beams

    Science.gov (United States)

    Liu, Qingfang; Wang, Zhuanzi; Zhou, Libin; Qu, Ying; Lu, Dong; Yu, Lixia; Du, Yan; Jin, Wenjie; Li, Wenjian

    2013-06-01

    In order to analyze the relationship between plant growth and cytological effects, wheat dry seeds were exposed to various doses of 12C6+ beams and the biological endpoints reflecting plant growth and root apical meristem (RAM) activities were investigated. The results showed that most of the seeds were able to germinate normally within all dose range, while the plant survival rate descended at higher doses. The seedling growth including root length and seedling height also decreased significantly at higher doses. Mitotic index (MI) in RAM had no changes at 10 and 20 Gy and decreased obviously at higher doses and the proportion of prophase cells had the same trend with MI. These data suggested that RAM cells experienced cell cycle arrest, which should be responsible for the inhibition of root growth after exposure to higher doses irradiation. Moreover, various types of chromosome aberrations (CAs) were observed in the mitotic cells. The frequencies of mitotic cells with lagging chromosomes and these with anaphase bridges peaked around 60 Gy, while the frequencies of these with fragments increased as the irradiation doses increased up to 200 Gy. The total frequencies of mitotic cells with CAs induced by irradiation increased significantly with the increasing doses. The serious damage of mitotic chromosomes maybe caused cell cycle arrest or cell death. These findings suggested that the influences of 12C6+ beams irradiation on plant growth were related to the alternation of mitotic activities and the chromosomal damages in RAM.

  4. A GRAS-like gene of sunflower (Helianthus annuus L.) alters the gibberellin content and axillary meristem outgrowth in transgenic Arabidopsis plants.

    Science.gov (United States)

    Fambrini, M; Mariotti, L; Parlanti, S; Salvini, M; Pugliesi, C

    2015-11-01

    The GRAS proteins belong to a plant transcriptional regulator family that function in the regulation of plant growth and development. Despite their important roles, in sunflower only one GRAS gene (HaDella1) with the DELLA domain has been reported. Here, we provide a functional characterisation of a GRAS-like gene from Helianthus annuus (Ha-GRASL) lacking the DELLA motif. The Ha-GRASL gene contains an intronless open reading frame of 1,743 bp encoding 580 amino acids. Conserved motifs in the GRAS domain are detected, including VHIID, PFYRE, SAW and two LHR motifs. Within the VHII motif, the P-H-N-D-Q-L residues are entirely maintained. Phylogenetic analysis reveals that Ha-GRASL belongs to the SCARECROW LIKE4/7 (SCL4/7) subfamily of the GRAS consensus tree. Accumulation of Ha-GRASL mRNA at the adaxial boundaries from P6/P7 leaf primordia suggests a role of Ha-GRASL in the initiation of median and basal axillary meristems (AMs) of sunflower. When Ha-GRASL is over-expressed in Arabidopsis wild-type plants, the number of lateral bolts increases differently from untransformed plants. However, Ha-GRASL slightly affects the lateral suppressor (las-4-) mutation. Therefore, we hypothesise that Ha-GRASL and LAS are not functionally equivalent. The over-expression of Ha-GRASL reduces metabolic flow of gibberellins (GAs) in Arabidopsis and this modification could be relevant in AM development. Phylogenetic analysis includes LAS and SCL4/7 in the same major clade, suggesting a more recent separation of these genes with respect to other GRAS members. We propose that some features of their ancestor, as well as AM initiation and outgrowth, are partially retained in both LAS and SCL4/7. © 2015 German Botanical Society and The Royal Botanical Society of the Netherlands.

  5. Meristem-localized inducible expression of a UDP-glycosyltransferase gene is essential for growth and development in pea and alfalfa.

    Science.gov (United States)

    Woo, H H; Orbach, M J; Hirsch, A M; Hawes, M C

    1999-12-01

    PsUGT1, which encodes a microsomal UDP-glucuronosyltransferase, was cloned from root tips of Pisum sativum. PsUGT1 expression is correlated with mitosis and strongly induced in dividing cells. A region at the C terminus of the encoded protein is closely related to the UDP-glucuronic acid binding site consensus sequence, and the protein encoded by PsUGT1 catalyzes conjugation of UDP-glucuronic acid to an unknown compound. Overexpression of PsUGT1 sense mRNA has no detectable effect on transgenic pea hairy root cultures or regenerated alfalfa. However, inhibiting PsUGT1 expression by the constitutive expression of antisense mRNA (under the control of the cauliflower mosaic virus 35S promoter) markedly retards growth and development of transgenic alfalfa. Cell structure and organization in the antisense plants are similar to those of controls, but plant growth is reduced and development is delayed. This inhibition in growth is correlated with a twofold delay in the time required for completion of a cell cycle and with a >99% inhibition of border cell production. Inhibition of PsUGT1 expression by meristem-localized inducible expression of PsUGT1 antisense mRNA (under the control of its own promoter) is lethal both in pea hairy roots and in transgenic alfalfa plants. These results indicate that PsUGT1 expression is required for normal plant growth and development, and they are consistent with the hypothesis that this UDP-glycosyltransferase regulates activity of a ligand(s) needed for cell division.

  6. Effect of the gamma radiation in the metabolic activity of the apical meristem of asparagus (Asparagus officinalis); Efecto de la radiacion gamma en la actividad metabolica del meristemo apical de esparrago (Asparagus officinalis)

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez E, A.; Orozco A, J.A.; Troncoso R, R.; Ojeda C, A.J.; Mercado R, J.N.; Gardea B, A.; Tiznado H, M.E. [Centro de Investigacion en Alimentacion y Desarrollo, A.C. Carretera a la Victoria km. 0.6, A.P. 1735, Hermosillo, Sonora (Mexico); Melendrez A, R. [Universidad de Sonora, A.P. 5-088, Hermosillo, Sonora (Mexico)]. e-mail: aestrada@cascabel.ciad.mx

    2007-07-01

    The asparagus (Asparagus officinalis) is an agricultural product whose production generates a great quantity of wages as well as foreign currencies for the country because a great part of its production is exported to international markets. In direct reason to the high metabolic activity of the apical meristem, this product it possesses a short shelf life under good conditions of commercialization. Due to the above mentioned, the present work had as objective to evaluate the effect of the gamma radiation in the metabolic activity of the apical meristem of turions of asparagus during the postharvest. Turions of asparagus variety Brock of standard quality was treated with gamma radiation to absorbed dose of 1.0, 1.5, 2.0, 2.5 and 3.0 kGy using an irradiator of {sup 60}Co and stored in one controlled temperature camera maintained at 2 C during 8 days. During the experiment, the camera stayed in darkness and under conditions of high relative humidity by means of the water aspersion. Immediately before the one treatment and after 1, 2, 4 and 8 days of storage, the asparagus were sampled to evaluate the breathing speed (VRCG) by means of gas chromatography and scanning differential calorimetry (VRCDB), ethylene production (PE) by means of gas chromatography and production of metabolic heat of the apical meristem of the asparagus by means of scanning differential calorimetry (Q). Its were not found effects due to the gamma radiation in the variables of VRCG, VRCDB and Q. However, for the PE case, it was found that the doses of 1.5 and 2.5 reduced the PE from the first day of storage, while the 3 kGy dose achievement to eliminate completely the ethylene production from the first day of storage. It was concluded that the gamma radiation at the used levels in the present experiment doesn't reduce the metabolic activity of the apical meristem of the turion of asparagus although it can to improve the postharvest quality from the asparagus when reducing the ethylene

  7. lAA and BAP affect protein phosphorylation-dependent processes during sucrose-mediated G1 to S and G2 to M transitions in root meristem cells of Vicia faba

    Directory of Open Access Journals (Sweden)

    Justyna Teresa Polit

    2011-01-01

    Full Text Available In carbohydrate-starved root meristems of Vicia faba subsp. minor, the expression of two Principal Control Points located at the final stages of the G1 (PCP1 and G2 (PCP2 phases has been found to be correlated with a marked decrease of protein phosphorylation within cell nuclei, nucleoli and cytoplasm. Adopting the same experimental model in our present studies, monoclonal FITC conjugated antibodies that recognize phosphorylated form of threonine (αTPab-FITC were used to obtain an insight about how the indole-3-acetic acid (IAA, benzyl-6-aminopurine (BAP, and the mixture of both phytohormones influence the time-course changes in an overall protein phosphorylation during sucrose-mediated PCP1→S and PCP2→M transitions. Unsuspectedly, neither IAA, BAP, nor the mixture of both phytohormones supplied in combination with sucrose did up-regulate protein phosphorylation. However using the block-and-release method, it was shown that root meristems of Vicia provided with sucrose alone indicated higher levels of αTPab-FITC. Contrarily, phytohormones supplied in combination with sucrose induced apparent decline in phosphorylation of cell proteins, which - when compared with the influence of sucrose alone - became increasingly evident in time. Thus, it seems probable, that a general decline in the amount of αTPab-FITC labeled epitopes may overlay specific phosphorylations and dephosphorylations governed by the main cell cycle kinases and phosphatases.

  8. Propagación in vitro de Carica papaya var. PTM-331 a partir de meristemos apicales In vitro propagation of Carica papaya var. PTM-331 from apical meristem

    Directory of Open Access Journals (Sweden)

    Reynaldo Solis L.

    2012-02-01

    Full Text Available El trabajo consistió en desarrollar un protocolo de propagación in vitro de la variedad de papaya PTM-331 a partir de meristemos apicales, con la finalidad de obtener plántulas vigorosas y libres de enfermedades, empleando la técnica del cultivo de tejidos. Las yemas apicales empleadas fueron obtenidas de plantas cultivadas en invernadero, los cuales fueron usados como explantes para la extracción de meristemos. La mejor diferenciación de meristemos se logró en el medio basal MS suplementado con 0,5 mg.L-1 de BAP, 0,5 mg.L-1 de AIA y 10 mg.L-1 de adenina. La mejor multiplicación se logró con el medio MS suplementado con 0,5 mg.L-1 de BAP, 0,5 mg.L-1 de AIA y 0,3 mg.L-1 de AG3, con un coeficiente de multiplicación de 3,42; mientras que el mejor medio para el enraizamiento fue la combinación del medio MS, 3 mg.L-1 de AIB y 5 mg.L-1 de adenina, donde se obtuvo 83,33% de plantas enraizadas.An in vitro protocol was develop to propagate variety of papaya PTM-331 from apical meristems, with the objective of obtaining vigorous and disease-free seedlings, using tissue culture techniques. Apical buds were obtained from seedlings cultivated in greenhouse and used as explants for meristem dissection. Meristems were cultured on MS basal medium supplemented with 0,5 mg.L-1 of BAP, 0,5 mg.L-1 of AIA and 10 mg.L-1 of adenine for their differentiation. The best multiplication of explants was achieved with the combination of MS medium supplemented with 0,5 mg.L-1 of BAP, 0,5 mg.L-1 of AIA and 0,3 mg.L-1 of AG3, where largest seedlings, with more shoots were obtained. The best medium for rooting was the combination of MS, 3 mg.L-1 of AIB and 5 mg.L-1 of adenine, where 83,33% of rooted plants were obtained.

  9. Determination of the cause of the symptoms on yellow yam (Dioscorea cayenensis Lam.) leaf tissue and their eradication, enriching the culture medium and using techniques of meristem culture, thermo and chemotherapy on in vitro conditions

    International Nuclear Information System (INIS)

    Brenes Huertas, Mauricio

    2010-01-01

    Yams (Dioscorea spp) has been cultivated for exportation in Costa Rica, in North Huetar region. In vitro culture technique has been used for multiplying planting material for many advantages. However, cleaning of viruses that affect has been ineffective. Viruses such as: the potyvirus, potexvirus, cucumovirus . Methods like meristem culture, chemotherapy, thermotherapy and combinations of these have been used for the elimination of virus in plant species. The plants were evaluated in indexing assays, observing symptoms, serological methods and electron microscopy, among others. Other problems that have been affecting in vitro plant are deficient culture media in some nutrient. The presence of some abnormal characteristics in leaf tissue was determined whether have been caused by a virus or a nutritional deficiency in the culture medium. The presence of the virus has tried to find using ELISA and electron microscopy. Tests meristem culture, thermotherapy and chemotherapy have been made for the eradication of a possible virus; which have been assessed by observation of symptomatology and ELISA. The efficiency of the culture medium was evaluated to enrich it with nitrogen or excess iron. None of the suspected virus found in ELISA tests. Filaments are presumably viral particles were found through analysis of ultrastructure, as well as alterations in chloroplasts which indicated the presence of a pathogen or toxicity. Thermotherapy and chemotherapy with the concentration of 40 mg/L of ribavirin have been the most effective for the elimination of symptoms in virus eradication treatments. Assessments nutrient concentrations have shown that the differences between the various treatments used were undetectable. The symptoms presented were caused, according to the conclusions, by a virus which should preferably deal with thermotherapy. (author) [es

  10. An approach towards genetically engineered cell fate mapping in maize using the Lc gene as a visible marker: transactivation capacity of Lc vectors in differentiated maize cells and microinjection of Lc vectors into somatic embryos and shoot apical meristems.

    Science.gov (United States)

    Lusardi, M C; Neuhaus-Url, G; Potrykus, I; Neuhaus, G

    1994-04-01

    To establish a system for genetically engineered cell fate mapping, different vectors carrying the Lc gene, a member of the R gene family, were delivered into embryonic and meristematic cells of maize by the microinjection technique. Vectors in which the Lc cDNA is driven either by a constitutive promoter (CaMV 35S), with or without the Adh1 intron 1 of maize, or a tissue-specific promoter (phosphoenolpyruvate carboxylase, PEPC) as well as self-replicating wheat dwarf virus (WDV) vectors carrying a Lc-expression-cassette, have been tested. The ability of these vectors to transactivate was evaluated in mesophyll-derived protoplasts of the maize genotype appropriate for these microinjection experiments. The expression product of the introduced Lc gene can substitute for mutated R and B loci, resulting in anthocyanin production. Analogous results were obtained by microinjection into organized tissues, where transactivation of anthocyanin biosynthesis resulted in pigmented sectors in somatic embryos (B79) and in the leaves of plants regenerated from the cultivated shoot apical meristems (K55, r-g, b). The tissue-specific appearance of pigmented sectors in leaves, using the mesophyll-specific PEPC promoter suggests the possibility of using this approach for layer-specific cell fate studies. The presence of the introduced plasmids in leaves showing red sectors 20-30 days after injection was proven by PCR analysis.

  11. Conservação in vitro do germoplasma de capim-elefante por meio da micropropagação de meristemas axilares In vitro conservation of elephantgrass germplasm of micropropagation of axillary meristems

    Directory of Open Access Journals (Sweden)

    Maria Coletta Vidigal

    1998-09-01

    Full Text Available Na conservação m vitro do capim-elefante foi observado que, ao longo dos subcultivos sucessivos de meristemas picais, ocorre gradual perda de vigor nas plântulas. Essa limitação torna necessária a reintrodução de acessos na coleção, comprometendo a eficiência do processo. Visando solucionar o problema, foi conduzido um estudo com 51 cultivares de capimelefante, onde, na repicagem efetuada a cada 4 a 6 meses, foram inoculados meristemas axilares da plântula, dispostos horizontalmente sobre meio MS, adicionado ou não de ácido naftalenoacético (ANA. Neste ciclo, que durou 45 dias, foram avaliadas as seguintes variáveis: número e comprimento dos explantes, gemas brotadas por explante, início e vigor da brotação, número de brotos desenvolvidos e percentagem de morte. Os resultados sugerem que esse método melhorou o vigor acentuadamente; embora as respostas, com e sem adição de ANA ao meio, tenham sido muito variadas entre cultivares. Apenas a cv. Mercker Comum Pinda não apresentou resposta satisfatória, devendo ser futuramente submetida a outras alternativas para propagação. Com base na produção de brotos, as cvs. Napier e Sem Pêlo apresentaram o melhor desempenho, na presença de ANA. O método mostrou-se promissor também pelo uso mínimo de reguladores do crescimento, reduzindo custos e a possibilidade de mutações.The continuous utiliwtion of explants obtainedfrom cultured apical meristems limits elephantgrass in vitro conservation because of gradual loss of vigor. Such a restriction makes it necessary to periodícally replace accessions in the coilection, reducing the efficiency of the technique. To overcome this problem, a study was carried out with 51 elephantgrass cultivars, where reculturing was conducted every 4 to 6 months using in vitro seediing axiliary meristems, with or without the addition of naphtaleneacetic acid (NAA to the MS culture médium. During this reculturing cycle, which lasted 45 days, the

  12. A 3D digital atlas of the Nicotiana tabacum root tip and its use to investigate changes in the root apical meristem induced by the Agrobacterium 6b oncogene.

    Science.gov (United States)

    Pasternak, Taras; Haser, Thomas; Falk, Thorsten; Ronneberger, Olaf; Palme, Klaus; Otten, Léon

    2017-10-01

    Using the intrinsic Root Coordinate System (iRoCS) Toolbox, a digital atlas at cellular resolution has been constructed for Nicotiana tabacum roots. Mitotic cells and cells labeled for DNA replication with 5-ethynyl-2'-deoxyuridine (EdU) were mapped. The results demonstrate that iRoCS analysis can be applied to roots that are thicker than those of Arabidopsis thaliana without histological sectioning. A three-dimensional (3-D) analysis of the root tip showed that tobacco roots undergo several irregular periclinal and tangential divisions. Irrespective of cell type, rapid cell elongation starts at the same distance from the quiescent center, however, boundaries between cell proliferation and transition domains are cell-type specific. The data support the existence of a transition domain in tobacco roots. Cell endoreduplication starts in the transition domain and continues into the elongation zone. The tobacco root map was subsequently used to analyse root organization changes caused by the inducible expression of the Agrobacterium 6b oncogene. In tobacco roots that express the 6b gene, the root apical meristem was shorter and radial cell growth was reduced, but the mitotic and DNA replication indexes were not affected. The epidermis of 6b-expressing roots produced less files and underwent abnormal periclinal divisions. The periclinal division leading to mature endodermis and cortex3 cell files was delayed. These findings define additional targets for future studies on the mode of action of the Agrobacterium 6b oncogene. © 2017 The Authors The Plant Journal © 2017 John Wiley & Sons Ltd.

  13. The effects of anti-DNA topoisomerase II drugs, etoposide and ellipticine, are modified in root meristem cells of Allium cepa by MG132, an inhibitor of 26S proteasomes.

    Science.gov (United States)

    Żabka, Aneta; Winnicki, Konrad; Polit, Justyna Teresa; Maszewski, Janusz

    2015-11-01

    DNA topoisomerase II (Topo II), a highly specialized nuclear enzyme, resolves various entanglement problems concerning DNA that arise during chromatin remodeling, transcription, S-phase replication, meiotic recombination, chromosome condensation and segregation during mitosis. The genotoxic effects of two Topo II inhibitors known as potent anti-cancer drugs, etoposide (ETO) and ellipticine (EPC), were assayed in root apical meristem cells of Allium cepa. Despite various types of molecular interactions between these drugs and DNA-Topo II complexes at the chromatin level, which have a profound negative impact on the genome integrity (production of double-strand breaks, chromosomal bridges and constrictions, lagging fragments of chromosomes and their uneven segregation to daughter cell nuclei), most of the elicited changes were apparently similar, regarding both their intensity and time characteristics. No essential changes between ETO- and EPC-treated onion roots were noticed in the frequency of G1-, S-, G2-and M-phase cells, nuclear morphology, chromosome structures, tubulin-microtubule systems, extended distribution of mitosis-specific phosphorylation sites of histone H3, and the induction of apoptosis-like programmed cell death (AL-PCD). However, the important difference between the effects induced by the ETO and EPC concerns their catalytic activities in the presence of MG132 (proteasome inhibitor engaged in Topo II-mediated formation of cleavage complexes) and relates to the time-variable changes in chromosomal aberrations and AL-PCD rates. This result implies that proteasome-dependent mechanisms may contribute to the course of physiological effects generated by DNA lesions under conditions that affect the ability of plant cells to resolve topological problems that associated with the nuclear metabolic activities. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

  14. Meristem Culture of Aloe vera L

    International Nuclear Information System (INIS)

    Kay Thi Mya; Thida Myint; Myo Han; Khin Maung Sein

    2005-10-01

    Shoot tips of Aloe vera L were excised and inoculated in basal and modified MS (Murashige and Skoog, 1962) medium. Growth regulators and growth factors were supplemented to the basal medium. Development of explants, initiation of callus and multiplication of shoots in culture were recorded.

  15. Evolutionary, interaction and expression analysis of floral meristem

    Indian Academy of Sciences (India)

    Administrator

    2 Guangxi Crop Genetic Improvement and Biotechnology Laboratory, Nanning 530007, China. 3 Agricultural .... μM CCC (Solarbio, Beijing, China, the purity is 98%), at 10 and 1 d before full bloom. Control plants were ... MEGA 5.0 software using the neighbor-joining (NJ) method, and the bootstrap test was replicated 1000 ...

  16. Comparison of meristem culture and heat therapy to clean garlic ...

    African Journals Online (AJOL)

    Experiment to detect garlic-infecting virus for three improved garlic varieties and to clean the virus were conducted in Ethiopia. Garlic cloves were planted in screen house at Biosciences Eastern and Central Africa-International Livestock Research Institute Hub Nairobi, Kenya in 2014. Reverse Transcription polymerase ...

  17. Comparison of Meristem Culture and Heat Therapy to Clean Garlic ...

    African Journals Online (AJOL)

    to Clean Garlic (Allium sativum L.) Infecting Virus in Ethiopia. Abel Debebe. Ethiopian Institute of Agricultural Research, Melkassa Agriculture Research Center. P.O. Box 436, Adama, Ethiopia, E-mail aabbeelldebebe@gmail.com. አህፅርኦት. የዚህ ጥናት ዓሊማ ሶስት የተሻሻለ የነጭ ሽንኩርት ዝርያዎችን የሚያጠቃ የቫይረስ ዓይነትን ...

  18. optimization of protocol for m apical meristem of embryonic axes

    African Journals Online (AJOL)

    userpc

    source of dietary protein with both its dry gra and vegetative parts containing 23 and other important food .... percentage of total embryonic axes cultured) were taken at regular intervals. Number of elongated shoots per ... or de novoorganogenesis has earlier bee reported from various explants (for a review se. Saniet al.

  19. Evolutionary, interaction and expression analysis of floral meristem

    Indian Academy of Sciences (India)

    Administrator

    Rongrong Guo 1,2, Bo Wang 3, Ling Lin 4, Guo Cheng4, Sihong Zhou 2, Shuyu Xie 4,. Xiaofang Shi 4, Muming Cao 4, Ying Zhang 4, Xianjin Bai 1*. 1 Guangxi Academy of Agricultural Sciences, Nanning 530007, China. 2 Guangxi Crop Genetic Improvement and Biotechnology Laboratory, Nanning 530007, China.

  20. Shoot apical meristem and plant body organization: a cross-species comparative study

    Czech Academy of Sciences Publication Activity Database

    Schnablová, Renáta; Herben, Tomáš; Klimešová, Jitka

    2017-01-01

    Roč. 120, č. 5 (2017), s. 833-843 ISSN 0305-7364 R&D Projects: GA ČR GB14-36079G Institutional support: RVO:67985939 Keywords : Corner's rule * cell number * cell size Subject RIV: EF - Botanics OBOR OECD: Plant sciences, botany Impact factor: 4.041, year: 2016

  1. Converging Light, Energy and Hormonal Signaling Control Meristem Activity, Leaf Initiation, and Growth.

    Science.gov (United States)

    Mohammed, Binish; Bilooei, Sara Farahi; Dóczi, Róbert; Grove, Elliot; Railo, Saana; Palme, Klaus; Ditengou, Franck Anicet; Bögre, László; López-Juez, Enrique

    2018-02-01

    The development of leaf primordia is subject to light control of meristematic activity. Light regulates the expression of thousands of genes with roles in cell proliferation, organ development, and differentiation of photosynthetic cells. Previous work has highlighted roles for hormone homeostasis and the energy-dependent Target of Rapamycin (TOR) kinase in meristematic activity, yet a picture of how these two regulatory mechanisms depend on light perception and interact with each other has yet to emerge. Their relevance beyond leaf initiation also is unclear. Here, we report the discovery that the dark-arrested meristematic region of Arabidopsis ( Arabidopsis thaliana ) experiences a local energy deprivation state and confirm previous findings that the PIN1 auxin transporter is diffusely localized in the dark. Light triggers a rapid removal of the starvation state and the establishment of PIN1 polar membrane localization consistent with auxin export, both preceding the induction of cell cycle- and cytoplasmic growth-associated genes. We demonstrate that shoot meristematic activity can occur in the dark through the manipulation of auxin and cytokinin activity as well as through the activation of energy signaling, both targets of photomorphogenesis action, but the organ developmental outcomes differ: while TOR-dependent energy signals alone stimulate cell proliferation, the development of a normal leaf lamina requires photomorphogenesis-like hormonal responses. We further show that energy signaling adjusts the extent of cell cycle activity and growth of young leaves non-cellautonomously to available photosynthates and leads to organs constituted of a greater number of cells developing under higher irradiance. This makes energy signaling perhaps the most important biomass growth determinant under natural, unstressed conditions. © 2018 American Society of Plant Biologists. All Rights Reserved.

  2. Esau's Plant anatomy: meristems, cells, and tissues of the plant body : their structure, function, and development

    National Research Council Canada - National Science Library

    Evert, Ray Franklin; Esau, Katherine; Eichhorn, Susan E

    2006-01-01

    ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xix Chapter 1 Structure and Development of the Plant Body- An Overview . . . . . . . . . . . . . . . . . . . . . . . . 1 Internal Organization of the Plant Body...

  3. JACKDAW controls epidermal patterning in the Arabidopsis root meristem through a non-cell-autonomous mechanism.

    Science.gov (United States)

    Hassan, Hala; Scheres, Ben; Blilou, Ikram

    2010-05-01

    In Arabidopsis, specification of the hair and non-hair epidermal cell types is position dependent, in that hair cells arise over clefts in the underlying cortical cell layer. Epidermal patterning is determined by a network of transcriptional regulators that respond to an as yet unknown cue from underlying tissues. Previously, we showed that JACKDAW (JKD), a zinc finger protein, localizes in the quiescent centre and the ground tissue, and regulates tissue boundaries and asymmetric cell division by delimiting SHORT-ROOT movement. Here, we provide evidence that JKD controls position-dependent signals that regulate epidermal-cell-type patterning. JKD is required for appropriately patterned expression of the epidermal cell fate regulators GLABRA2, CAPRICE and WEREWOLF. Genetic interaction studies indicate that JKD operates upstream of the epidermal patterning network in a SCRAMBLED (SCM)-dependent fashion after embryogenesis, but acts independent of SCM in embryogenesis. Tissue-specific induction experiments indicate non-cell-autonomous action of JKD from the underlying cortex cell layer to specify epidermal cell fate. Our findings are consistent with a model where JKD induces a signal in every cortex cell that is more abundant in the hair cell position owing to the larger surface contact of cells located over a cleft.

  4. Regulation of cell fate and meristem maintenance in Arabidopsis root development

    NARCIS (Netherlands)

    ten Hove, C.A.

    2010-01-01

    Asymmetric cell division is an essential and universal mechanism for generating diversity and pattern in multicellular organisms. Divisions generating daughter cells different in size, shape, identity and function are fundamental to many developmental processes including fate specification, tissue

  5. THE SYNTHESES OF DEOXYRIBONUCLEIC ACID AND HISTONE IN THE ONION ROOT MERISTEM

    Science.gov (United States)

    Bloch, David P.; MacQuigg, Robert A.; Brack, Sheilah D.; Wu, Jung-Rung

    1967-01-01

    A comparison of the times necessary to incorporate tritium-labeled lysine and arginine into histones and tritium-labeled thymidine into DNA indicates that the periods of DNA and histone synthesis prior to division closely coincide. (The comparison was made by determining the times necessary, after pulse labeling, for cells with marked chromosomes to enter and then leave the division stages.) An additional period of chromosomal protein synthesis, of short duration, occurs late in interphase. Most of the chromosomal proteins appear either to be synthesized in the nucleus or to migrate there shortly after synthesis. Much of this protein is conserved from one division to the next. Studies of the effects of puromycin and fluorodeoxyuridine on the syntheses of DNA and histone suggest that continuation of DNA synthesis is dependent on a concurrent protein synthesis. Histone synthesis, on the other hand, can proceed at a normal rate under conditions in which DNA synthesis is inhibited. PMID:4226960

  6. Analysis of nodule meristem persistence and ENOD40 functioning in Medicago truncatula nodule formation

    NARCIS (Netherlands)

    Wan Xi,

    2007-01-01

    Medicago root nodules are formed as a result of the interaction of the plant with the soil-borne bacterium Sinorhizobium meliloti. Several plant genes are induced during nodule formation and MtENOD40 is one of the earliest genes activated. The precise function as well as the molecule

  7. PHABULOSA Controls the Quiescent Center-Independent Root Meristem Activities in Arabidopsis thaliana

    Czech Academy of Sciences Publication Activity Database

    Sebastian, J.; Ryu, K.H.; Zhou, J.; Tarkowská, Danuše; Tarkowski, P.; Cho, Y.H.; Yoo, S.D.; Kim, E.S.; Lee, J.Y.

    2015-01-01

    Roč. 11, č. 3 (2015) ISSN 1553-7390 Grant - others:GA MŠk(CZ) ED0007/01/01 Program:ED Institutional support: RVO:61389030 Keywords : STEM-CELL NICHE * POSTTRANSCRIPTIONAL REGULATION * GENE-EXPRESSION Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 7.528, year: 2014

  8. Analysis of nodule meristem persistence and ENOD40 functioning in Medicago truncatula nodule formation

    NARCIS (Netherlands)

    Wan Xi,

    2007-01-01

    Medicago root nodules are formed as a result of the interaction of the plant with the soil-borne bacterium Sinorhizobium meliloti. Several plant genes are induced during nodule formation and MtENOD40 is one of the earliest genes activated. The precise function as well as the molecule harboring the

  9. Clonal multiplication of Cymbidiums through tissue culture of the shoot meristem

    Energy Technology Data Exchange (ETDEWEB)

    Wimber, Donald E.

    1963-09-01

    The propagation of clonal varieties of some orchids is at times exasperatingly slow and occasionally an almost futile effort. Clonal multiplication is generally confined to dlvidlng mature plants and to starting plants from pseudobulbs. There is, of course, the specialized technique for obtaining Phalaenopsis plantlets from the aseptic culture of inflorescence nodes, but this is basically the same thing as propagating plants from pseudobulbs. In certain cases it is highly desirable to rapidly multiply certain clones of orchids. Awarded varieties could thereby be dispersed with great rapidity where now it may take decades for some clones to became fairly common. Commercial flower production would be very much enhanced if certain desirable clones could be multiplied ad infinitum within a short time. Orchid flower production could then be placed more on a par with many of the other cut flowers and the clonal peculiarities of some fo the current hybrids could be pampered instead of ignored. This paper describes a tissue culture method for the rapid propagation of Cymbidium clones.

  10. Mitochondrial type-I prohibitins of Arabidopsis thaliana are required for supporting proficient meristem development

    Czech Academy of Sciences Publication Activity Database

    Van Aken, O.; Pečenková, Tamara; van de Cotte, B.; De Rycke, R.; Eeckhout, D.; Fromm, H.; De Jaeger, G.; Witters, E.; Beemster, G.T.S.; Inzé, D.; Van Breusegem, F.

    2007-01-01

    Roč. 52, č. 5 (2007), s. 850-864 ISSN 0960-7412 Institutional research plan: CEZ:AV0Z50380511 Keywords : Arabidopsis * prohibitins * mitochondria Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 6.751, year: 2007

  11. Root-sprouting in myco-heterotrophic plants: prepackaged symbioses or overcoming meristem limitation?

    Czech Academy of Sciences Publication Activity Database

    Klimešová, Jitka

    2007-01-01

    Roč. 173, - (2007), s. 8-10 ISSN 0028-646X Institutional research plan: CEZ:AV0Z60050516 Keywords : root sprouting * bud bank * Myco-heterotrophic plants Subject RIV: EF - Botanics Impact factor: 5.249, year: 2007

  12. Esau's Plant anatomy: meristems, cells, and tissues of the plant body : their structure, function, and development

    National Research Council Canada - National Science Library

    Evert, Ray Franklin; Esau, Katherine; Eichhorn, Susan E

    2006-01-01

    ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The Body of a Vascular Plant Is Composed of Three Tissue Systems . . . . . . . . . . . . . . . . . . . . . Structurally Stem, Leaf, and Root Differ Primarily...

  13. [cDNA library construction from panicle meristem of finger millet].

    Science.gov (United States)

    Radchuk, V; Pirko, Ia V; Isaenkov, S V; Emets, A I; Blium, Ia B

    2014-01-01

    The protocol for production of full-size cDNA using SuperScript Full-Length cDNA Library Construction Kit II (Invitrogen) was tested and high quality cDNA library from meristematic tissue of finger millet panicle (Eleusine coracana (L.) Gaertn) was created. The titer of obtained cDNA library comprised 3.01 x 10(5) CFU/ml in avarage. In average the length of cDNA insertion consisted about 1070 base pairs, the effectivity of cDNA fragment insertions--99.5%. The selective sequencing of cDNA clones from created library was performed. The sequences of cDNA clones were identified with usage of BLAST-search. The results of cDNA library analysis and selective sequencing represents prove good functionality and full length character of inserted cDNA clones. Obtained cDNA library from meristematic tissue of finger millet panicle represents good and valuable source for isolation and identification of key genes regulating metabolism and meristematic development and for mining of new molecular markers to conduct out high quality genetic investigations and molecular breeding as well.

  14. Cirrosporium novae-zelandiae, an enigmatic coelomycete with meristem arthroconidia, with ancestors in the Eurotiomycetes

    Czech Academy of Sciences Publication Activity Database

    Réblová, Martina; Seifert, K. A.

    2012-01-01

    Roč. 104, č. 6 (2012), s. 1315-1324 ISSN 0027-5514 R&D Projects: GA ČR GAP506/12/0038 Institutional support: RVO:67985939 Keywords : conidium ontogeny * multigene phylogeny * Mycocaliciomycetidae Subject RIV: EF - Botanics Impact factor: 2.110, year: 2012

  15. Plant Aurora kinases play a role in maintenance of primary meristems and control of endoreduplication

    Czech Academy of Sciences Publication Activity Database

    Petrovská, Beáta; Cenklová, Věra; Pochylová, Žaneta; Kourová, Hana; Doskočilová, Anna; Plíhal, Ondřej; Binarová, Lenka; Binarová, Pavla

    2012-01-01

    Roč. 193, č. 3 (2012), s. 590-604 ISSN 0028-646X R&D Projects: GA ČR(CZ) GA204/07/1169; GA ČR GP204/09/P155; GA ČR(CZ) GD204/09/H084; GA MŠk(CZ) LC06034; GA MŠk LC545; GA AV ČR IAA500200719 Grant - others:GA MŠk(CZ) ED0007/01/01 Program:ED Institutional research plan: CEZ:AV0Z50380511; CEZ:AV0Z50200510 Keywords : Arabidopsis thaliana * AtTPX2 (targeting protein for Xklp2) * Aurora kinases Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 6.736, year: 2012

  16. Chromosome aberrations induced by curcumin and aloin in Allium cepa L. root meristem cells

    OpenAIRE

    PALANIKUMAR, Loganathan; RAGUNATHAN, Irulappan; PANNEERSELVAM, Natarajan

    2014-01-01

    To date, a variety of plant compounds have been studied extensively with regard to anti-mutagenic, anti-carcinogenic, and anti-genotoxic activity. Nevertheless, very few of them have been studied in terms of clastogenicity. In the present study the clastogenic activity of curcumin (the active component of turmeric) and aloin (the active component of aloe) was evaluated at doses of 5, 10, 20, 30, 50, and 100 µg/mL for 4, 8, and 12 h. Both curcumin and aloin had significant dose- and time-depen...

  17. Chromosomal aberrations induced by Glycidol in Allium cepa L root meristem cells

    OpenAIRE

    N.Panneerselvam; L.Palanikumar; S.Gopinathan

    2012-01-01

    Glycidol is used as a stabilizer in the manufacture of vinyl polymers and natural oils and as an intermediate in the synthesis of glycerol, glycidyl ethers, and amines. It is also used as an alkylating agent,demulsifier, and dye-leveling agent and for sterilizing milk of magnesia. Glycidol is an alkylating agent which reacts readily with glutathione; it causes a decrease in glutathione content in rat liver, probably reflecting its binding to glutathione. It is a suspected reproductive toxican...

  18. Dichlorophen and Dichlorovos mediated genotoxic and cytotoxic assessment on root meristem cells of Allium cepa

    Directory of Open Access Journals (Sweden)

    Sibhghatulla Shaikh

    2012-06-01

    Full Text Available Plants are direct recipients of agro – toxics and therefore important materials for assessing environmental chemicals for genotoxicity. The meristematic mitotic cell of Allium cepa is an efficient cytogenetic material for chromosome aberration assay on environmental pollutants. Onion root tips were grown on moistened filter paper in petri dish at room temperature. Germinated root tips were then exposed to three concentrations of each pesticide for 24 h. About 1 – 2 mm length of root tip was cut, fixed in cornoy’s fixative, hydrolyzed in warm 1 N HCL, stained with acetocarmine and squashed on glass slide. About 3000 cells were scored and classified into interphase and normal or aberrant division stage. Cytotoxicity was determined by comparing the mitotic index (MI of treated cells with that of the negative control. The MI of cells treated with Dichlorophen and Dichlorovos at one or more concentration was half or less than that of control are said to be cytotoxic. Genotoxicity was measured by comparing the number of cells/1000 in aberrant division stages at each dose with the negative control using Mann – Whitney U test. Both Dichlorophen and Dichlorovos are genotoxic at higher concentrations i.e. 0.001%, 0.002% and 0.028%, 0.056% inducing chromosome fragment, chromosome lagging and bridges, stick chromosome and multipolar anaphase.

  19. Gamma induced chromosomal aberrations in meristem cells of cotton hybrids and their parental forms

    International Nuclear Information System (INIS)

    Kraevoj, S.Ya.; Akhmedova, M.M.; Amirkulov, D.

    1977-01-01

    The effect of gamma quanta on the first mitoses in the small roots of cotton hybrids and their parents results in different frequency of chromosome rearrangements in them. It has been proved that the frequency of chromosome aberrations is different in hybrids and different varieties of cotton. With increase in irradiation doses (from 10 to 30 kR) the frequency of chromosome aberrations goes up in all varieties and hybrids studies. The type of chromosome rearrangements in hybrids and their parents depends on the irradiation dose

  20. Converging Light, Energy and Hormonal Signaling Control Meristem Activity, Leaf Initiation, and Growth1[OPEN

    Science.gov (United States)

    Mohammed, Binish; Bilooei, Sara Farahi; Grove, Elliot; Railo, Saana; Palme, Klaus

    2018-01-01

    The development of leaf primordia is subject to light control of meristematic activity. Light regulates the expression of thousands of genes with roles in cell proliferation, organ development, and differentiation of photosynthetic cells. Previous work has highlighted roles for hormone homeostasis and the energy-dependent Target of Rapamycin (TOR) kinase in meristematic activity, yet a picture of how these two regulatory mechanisms depend on light perception and interact with each other has yet to emerge. Their relevance beyond leaf initiation also is unclear. Here, we report the discovery that the dark-arrested meristematic region of Arabidopsis (Arabidopsis thaliana) experiences a local energy deprivation state and confirm previous findings that the PIN1 auxin transporter is diffusely localized in the dark. Light triggers a rapid removal of the starvation state and the establishment of PIN1 polar membrane localization consistent with auxin export, both preceding the induction of cell cycle- and cytoplasmic growth-associated genes. We demonstrate that shoot meristematic activity can occur in the dark through the manipulation of auxin and cytokinin activity as well as through the activation of energy signaling, both targets of photomorphogenesis action, but the organ developmental outcomes differ: while TOR-dependent energy signals alone stimulate cell proliferation, the development of a normal leaf lamina requires photomorphogenesis-like hormonal responses. We further show that energy signaling adjusts the extent of cell cycle activity and growth of young leaves non-cellautonomously to available photosynthates and leads to organs constituted of a greater number of cells developing under higher irradiance. This makes energy signaling perhaps the most important biomass growth determinant under natural, unstressed conditions. PMID:29284741

  1. Cell cycle arrest induced by theophylline in root meristem of Haplopappus gracilis.

    Science.gov (United States)

    Levi, M; Chiatante, D; Sparvoli, E

    1983-10-01

    Theophylline, an inhibitor of cyclic nucleotide phosphodiesterase, induced a block of the cell cycle in G1, a temporary arrest in G2 and 70% decrease in the uptake of labelled thymidine in roots of Haplopappus. These effects are compared to those previously found with aminophylline and discussed in view of the possible involvement of cAMP in the regulation of the cell cycle in plants.

  2. The effects of low doses of different radiation qualities on Vicia faba bean root meristems

    International Nuclear Information System (INIS)

    Marshall, I.

    1982-01-01

    The effects of low doses of different radiation qualities have been investigated using the micronuclei induction in Vicia faba bean roots as an indicator. The radiation qualities used were: 60 Co-gamma rays, high energy neutrons (maximum energy 600 MeV), low energy neutrons (mean energy 2.35 MeV), negative pions in the plateau region and negative pions in the stopping region. It was found that the best fit to the gamma ray data was obtained by using a linear+quadratic relationship, while in the case of the other radiation qualities a linear equation, represented the best fit, implying the non-existence of a threshold dose. No dose-rate, fractionation or oxygen effect was found for gamma radiation in the low dose region (below 20cGy) where the linear dependence between effect and dose is dominant. In contrast, in the high dose region these effects were present as normally expected. Fractionation experiments were carried out using high energy neutrons and pion radiation. No recovery was observed after neutron radiation while some recovery was found for the pion radiation. The RBE values found for the two neutron energies were in the high dose region 4.7 +- 0.4 and 11.8 +- 1.3. In the low dose region the RBE value approached a constant value of 25.4 +- 4.4 for the high energy neutrons and 63.7 +- 12.0 for the low energy neutrons. (orig./MG) [de

  3. Abnormal mitosis in root meristem cells of Allium cepa L. induced by ...

    African Journals Online (AJOL)

    This investigation was aimed to find mitotic abnormalities as cytological evidence induced by the dye in root tip cells of onion (Allium cepa L.) grown in different concentrations: 0.01, 0.05, 0.1, 0.5 and 1.0% (weight per volume) prepared in distilled water in separate treatment schedules for 24 and 48 h. Mitotic aberrations ...

  4. Cytogenetic effects of combined impact caused by 232Th and ions of alkali and heavy metals to plant meristem

    International Nuclear Information System (INIS)

    Evseeva, T.I.; Khramova, E.S.; Geras'kin, S.A.

    2001-01-01

    The cytogenetic effects of complex and separate action of K, Cd and 232 Th on plant - Tradescantia (clone 02) and Allium cepa - meristematic root tip cells were investigated. It was shown that cytogenetic effects of 232 Th result mainly in its ability to induce genome damages. Cd in concentration studied (it was equal to 60 mg/l) was not induce vagrants increasing and this effect does not intensified by the combined action with 232 Th. Cd induced the essential increase (1.5 times more than in control group) of the chromosome type aberration frequency and the fragments frequency, while the mitotic index was decreased. It was shown that the difference in plant cell responses to K and Cd complex action with one and the same agent - 232 Th - is due to the differences in the chemical element characteristics and their significance for biological objects. The element vital for biological objects - K -protect plant cells from 232 Th effect, but the two highly toxic metals - 232 Th and Cd - complex action results in the synergic increasing of their effects on plant cells. (author)

  5. A Protocol for Rapid, Measurable Plant Tissue Culture Using Stem Disc Meristem Micropropagation of Garlic ("Allium Sativum L.")

    Science.gov (United States)

    Peat, Gerry; Jones, Meriel

    2012-01-01

    Plant tissue culture is becoming an important technique for the mass propagation of plants. Problems with existing techniques, such as slow growth and contamination, have restricted the practical work in plant tissue culture carried out in schools. The new protocol using garlic meristematic stem discs explained in this article addresses many of…

  6. Effects of long-term pruning, meristem origin, and branch order on the rooting of Douglas-fir stem cuttings.

    Science.gov (United States)

    D.L. Copes

    1992-01-01

    The rooting percentages of 14 Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) clones were examined annually from 1974 to 1988. The trees were 10 and 13 years old in 1974 and were pruned to 2.0 m in 1978 and 1979 and then recut annually to 0.5, 1.0, or 1.5 m, starting in 1983. The pruned trees showed no evidence of decreased rooting percentage...

  7. Biolistic-mediated transient gene expression in shoot apical meristems of the prickly-pear (Opuntia ficus-indica

    Directory of Open Access Journals (Sweden)

    Romulo Marino Llamoca-Zárate

    1999-01-01

    Full Text Available We have demonstrated the transient expression of the GUS gene in cells of the meristematic apical dome of Opuntia ficus-indica. DNA delivery into the cells was achieved using a biolistic PDS-1000He instrument from Bio-Rad Laboratories. The transforming DNA was coated in tungsten particles with diameter of 1.3 m m and the distance between the flying disk and the target tissue was 7.5cm and the shooting pressure was adjusted to 1200 psi. This is the first demonstration that the biolistic transformation system can be used to express a transgene in a member of the Cactaceae.Nós demonstramos a expressão transiente do gene GUS nas células do meristema apical de Opuntia ficus-indica. A introdução do DNA nas células foi realizada através de um sistema de biolística PDS-1000He da Bio-Rad Laboratories. Para transformação, partículas de tungstenio com diâmetro de 1,3 µm foram cobertas com DNA e a distância entre o disco das partículas e o tecido alvo foi de 7,5cm, a pressão de tiro foi 1200 psi. Esta é a primeira demonstração que o sistema de biolística de transformação pode ser usado para a expressão de transgenes nas cactáceas.

  8. Genotoxicity test of Maytenus rigida and Aristolochia birostris in the radicular meristem of the onion, Allium cepa

    Directory of Open Access Journals (Sweden)

    Sandra S. Mendes

    2011-09-01

    Full Text Available Medicinal plants are an important source of treatment for many ailments, although little is known of the potential genotoxic effects of most species. In the present study, two species from diverse and medicinally important genera - Maytenus rigida Mart., Celastraceae, and Aristolochia birostris Ducht, Aristolochiaceae - were analyzed to identify potentially significant secondary metabolites and the possible effects of their aqueous and alcoholic extracts on cell division in the onion root stem (genotoxicity test. The phytochemical testing revealed the presence of a number of potentially important secondary compounds in both species, including phenols, flavonoids, triterpenoids, steroids, and saponins. In the genotoxicity tests, no chromosomal abnormalities of any kind were observed in either species. In the case of M. rigida, a significant increase in mitotic activity was observed at the highest concentration. No significant tendency was recorded in A. birostris, although a considerable increase in the prophase was observed at all concentrations of the alcoholic extract. The triterpenoid content of both species may be especially important from a medicinal viewpoint, although recent findings on the carcinogenic potential of Aristolochia extracts demands caution in the interpretation of the results, and the need for further research.

  9. Genotoxicity test of Maytenus rigida and Aristolochia birostris in the radicular meristem of the onion, Allium cepa

    Directory of Open Access Journals (Sweden)

    Sandra S. Mendes

    2012-02-01

    Full Text Available Medicinal plants are an important source of treatment for many ailments, although little is known of the potential genotoxic effects of most species. In the present study, two species from diverse and medicinally important genera - Maytenus rigida Mart., Celastraceae, and Aristolochia birostris Ducht, Aristolochiaceae - were analyzed to identify potentially significant secondary metabolites and the possible effects of their aqueous and alcoholic extracts on cell division in the onion root stem (genotoxicity test. The phytochemical testing revealed the presence of a number of potentially important secondary compounds in both species, including phenols, flavonoids, triterpenoids, steroids, and saponins. In the genotoxicity tests, no chromosomal abnormalities of any kind were observed in either species. In the case of M. rigida, a significant increase in mitotic activity was observed at the highest concentration. No significant tendency was recorded in A. birostris, although a considerable increase in the prophase was observed at all concentrations of the alcoholic extract. The triterpenoid content of both species may be especially important from a medicinal viewpoint, although recent findings on the carcinogenic potential of Aristolochia extracts demands caution in the interpretation of the results, and the need for further research.

  10. Dichlorvos’un (DDVP Allium cepa L. Kök Ucu Meristem Hücrelerinde Mitoz Bölünme ve Kromozomlar Üzerine Etkileri

    Directory of Open Access Journals (Sweden)

    Hatice Soykan

    2014-06-01

    Full Text Available Özet. Çalışmamızda, DDVP’nin A. cepa’da kök uzunluğu, kök sayısı, mitoz bölünme ve kromozomlar üzerine olan etkileri araştırılmıştır. DDVP’nin 2ml/L, 4ml/L, 6 ml/L dozları 12, 24 ve 48 saat olmak üzere üç farklı süre ile A. cepa bitkisinin köklerine uygulanmıştır. Uygulama sonucu her soğandaki kökler sayılmış ve kök uzunlukları ölçülmüştür. Yapılan değerlendirmeler sonucu kontrol gruplarına göre uygulama gruplarının kök sayısının süreye bağlı olarak azalma gösterdiği görülmüştür. Uygulama gruplarının kök uzunlukları kontrol grupları ile karşılaştırıldıklarında uzunluğun genellikle doz ve süreye bağlı olarak azalma gösterdiği belirlenmiştir. Mikroskobik gözlemler sonucu elde edilen veriler tablolara aktarılmış ve SPSS 12.0 programında yapılan istatistiksel analizler ile sonuçlar değerlendirilmiştir. Elde edilen verilere göre DDVP’nin A.cepa bitkisinin köklerinde mitotik indeksi azalttığı saptanmıştır. Mitotik indeksin azalması süre artışına bağlı bir paralellik gösterirken, doz artışına bağlı bir paralellik göstermemektedir. İnsektisitin A.cepa bitkisinin köklerine uygulanması sonucu kromozomlarda hasarlar meydana gelmiştir. En fazla gözlenen kromozom hasarları yapışkanlık, yanlış kutuplaşma ve fragment oluşumudur. Bundan başka anafaz köprüsü ve mikronükleus oluşumları da görülmüştür. Abstract. In our study, effects of DDVP on A.cepa root length, root number, mitosis and chromosomes are determined.  Different doses of DDVP (2ml/L, 4 ml/L, 6 ml/L were applied to A. cepar oots with three different application periods (12h, 24h, 48h. Roots of tubers were counted and root lengths were measured after applications. Our results show that root numbers of application groups are decreased correlated with application time. When root length of application groups with control group is compared, root length decrease is generally seems to be correlated with application dosage and time. The data of microscobical observations were put in tables and evaluated with statistical analysis using SPSS 12.0. DDVP is determined to have a decreasing effect on mitoticindex of A. cepa .Decrease of mitotic index is correlated within crease of application time but not cerrelated with increase in appplication dosage. Chromosme aberrations were occured in A. cepa roots, after application of insecticide. Most observed chromosome defects are stickiness, pole deviation and fragmentation. Anaphase bridges and micro nuclei are also observed.

  11. Effects of water soluble oncostatic fraction from Rheum officinale Baill. rhizomes on Allium cepa root meristem. III. Morphological changes in cytoplasm

    Directory of Open Access Journals (Sweden)

    A. Dawidowicz-Grzegorzewska

    2015-01-01

    Full Text Available Spiral concentric and linear configurations of membraneous structures were observed in the cytoplasm of fixed meristematic cells from the root apex of Allium cepa under the light microscope. They appeared after incubation in sublethal and lethal conditions in Rheum ofiicinale rhizome extracts. During postincubation these structures disappeared. They were interpreted as ER membranes. On the basis of literature data the physiological significance of these structures is discussed. It would seem that they are an indication of enhanced metabolic activity evoked either exogenously by various injuries as a form of defence reaction of the protoplast or endogenously during cytodifferentiation. Prolonged treatment in ,noxious conditions causes the ER membranes to transform into inactive myelin structures

  12. A ¤Terminal Flower-1¤-like gene from perennial ryegrass involved in floral transition and axillary meristem identity

    DEFF Research Database (Denmark)

    Jensen, C.S.; Salchert, K.; Nielsen, K.K.

    2001-01-01

    Control of flowering and the regulation of plant architecture have been thoroughly investigated in a number of well-studied dicot plants such as Arabidopsis, Antirrhinum, and tobacco. However, in many important monocot seen crops, molecular information on plant reproduction is still limited. To i...

  13. Mitosis delay in cells of the root meristem of pea seedlings in S and G2-phases when irradiated with gamma-rays

    International Nuclear Information System (INIS)

    Gudkov, I.N.; Zezina, N.V.

    1976-01-01

    Irradiation (800 rads) of pea seedlings, synchronized by a 24-hr treatment with 0.03% hydroxyurea, at the stage of G 1 →S, induced a 12-hr delay of mitosis peak; an 8-hr delay, in the early S-phase; a 4-hr delay, in the middle of S-phase; a 10-hr delay in the late S- and a 14-16-hr delay, in G 2 -phase. The number of cells having chromosome aberrations at the mitosis peak was similar in all the phases under study

  14. Studies on the mode of action of auxin in plant development:analysis of the PIN6 gene in meristem function and cell differentiation

    OpenAIRE

    Medeiros, Violante de Faria e Maia Pacheco de, 1979-

    2007-01-01

    Tese de doutoramento em Biologia (Biologia Molecular), apresentada à Universidade de Lisboa através da Faculdade de Ciências, 2008 A proteína PIN6 é um dos membros menos caracterizados da família de proteínas PIN, associadas ao transporte de auxina em Arabidopsis thaliana. Nesta planta modelo, o transporte polar auxínico tem sido associado a diversos processos fisiológicos. Por exemplo, o movimento acropetal de IAA, do caule para a raíz, tem sido implicado no desenvolvimento de raízes late...

  15. Influence of histones and calcium and magnesium ions on the ultrastructure of chromatin in isolated nuclei of Pinus silvestris L. root meristem

    Directory of Open Access Journals (Sweden)

    Halina Michniewicz

    2015-01-01

    Full Text Available The width of chromatin fibrils in nuclei fixed in situ is about 10 nm. In nuclei isolated in the presence of Ca+2 and Mg+2 ions the fibrils coalesce, and thus their width secondarily increases, whereas in nuclei isolated without the presence of the cations the diameter of fibrils increases somewhat as compared with that in nuclei in situ, probably owing to absorption of nonchromatin nuclear proteins. Lysine histone extraction caused dispersion of condensed chromatin, and reintroduction of these proteins - its reconstruction. On the other hand, extraction and reintroduction of the arginine histone did not cause chromatin dispersion, but rather coalescence of the chromatin mass. Lysine histone extraction from material isolated in the presence of Ca+2 and Mg+2 ions caused the appearance of a large number of 10-nm fibrils, only sporadically seen in the control material, and disappearance of the 30-nm forms. Reintroduction of the lysine histone reduced the number of single fibrils and enhanced the appearance of coalescent form with 30 nm diameter. Removal of arginine histones did not produce disappearance of single fibrils, but reduced their diameter. Reintroduction of this fraction caused coalescence of chromatin threads, owing to which 90 per cent of the population consisted of fibrils with diameter around 30 nm.

  16. [Abnormal floral meristem development in transgenic tomato plants do not depend on the expression of genes encoding defense-related PR-proteins and antimicrobial peptides].

    Science.gov (United States)

    Khaliluev, M R; Chaban, I A; Kononenko, N V; Baranova, E N; Dolgov, S V; Kharchenko, P N; Poliakov, V Iu

    2014-01-01

    In this study, the morphological and cytoembryological analyses of the tomato plants transformed with the genes encoding chitin-binding proteins (ac and RS-intron-Shir) from Amaranthus caudatus L. andA. retroflexus L., respectively, as well as the gene amp2 encoding hevein-like antimicrobial peptides from Stellaria media L., have been performed. The transgenic lines were adapted to soil and grown the greenhouse. The analysis of putative transgenic tomato plants revealed several lines that did not differ phenotypically from the wild type plants and three lines with disruption in differentiation of the inflorescence shoot and the flower, as well as the fruit formation (modified plants of each line were transformed with a single gene as noted before). Abnormalities in the development of the generative organs were maintained for at least six vegetative generations. These transgenic plants were shown to be defective in the mail gametophyte formation, fertilization, and, consequently, led to parthenocarpic fruits. The detailed analysis of growing ovules in the abnormal transgenic plants showed that the replacement tissue was formed and proliferated instead of unfertilized embryo sac. The structure of the replacement tissue differed from both embryonic and endosperm tissue of the normal ovule. The formation of the replacement tissue occurred due to continuing proliferation of the endothelial cells that lost their ability for differentiation. The final step in the development of the replacement tissue was its death, which resulted in the cell lysis. The expression of the genes used was confirmed by RT-PCR in all three lines with abnormal phenotype, as well as in several lines that did not phenotypically differ from the untransformed control. This suggests that abnormalities in the organs of the generative sphere in the transgenic plants do not depend on the expression of the foreign genes that were introduced in the tomato genome. Here, we argue that agrobacterial transformation affects, directly or indirectly, expression of genes encoding for transcription factors that can activate a gene cascade responsible for the normal plant development.

  17. Indirect semiquantitative determination of p34cdc2 levels in G1 and G2 cells of the carbohydrate-starved root meristems in Vicia faba var. minor

    Directory of Open Access Journals (Sweden)

    Justyna Polit

    2014-01-01

    Full Text Available In eukaryotes, the 34kDa kinase (p34 encoded by the cdc2 gene is a key regulator of both the onset of DNA synthesis (G1 to S phase transition and the onset of mitosis (G1 to M phase transition. Using mouse anti-human PSTAIRE and FITClabelled goat antibodies, indirect semiquantitative determination of p34cdc2 levels was performed in meristematic cells from the control (intact and excised, carbohydrate-starved main roots of Vicia faba var. minor. No evident differences in the intensity of fluorescence was found either between the G1 and G2 cells or between the control cells and the cells arrested at both Principal Control Points by carbohydrate starvation. It seems thus, that the cell cycle block induced in meristematic cells of V. faba var. minor is not correlated with the absolute level of the key cell cycle enzyme responsible for phosphory-lution of cellular proteins, but primarily with the altered activity of p34cdc2.

  18. Arabidopsis CDS blastp result: AK242268 [KOME

    Lifescience Database Archive (English)

    Full Text Available n contains Pfam PF02365: No apical meristem (NAM) domain; No apical meristem gene (NAM), required for pattern formation in embryos and flowers-Petunia hybrida, PATCHX:E205713 1e-40 ...

  19. Arabidopsis CDS blastp result: AK288271 [KOME

    Lifescience Database Archive (English)

    Full Text Available n contains Pfam PF02365: No apical meristem (NAM) domain; No apical meristem gene (NAM), required for pattern formation in embryos and flowers-Petunia hybrida, PATCHX:E205713 5e-25 ...

  20. Arabidopsis CDS blastp result: AK243514 [KOME

    Lifescience Database Archive (English)

    Full Text Available n contains Pfam PF02365: No apical meristem (NAM) domain; No apical meristem gene (NAM), required for pattern formation in embryos and flowers-Petunia hybrida, PATCHX:E205713 2e-36 ...

  1. Arabidopsis CDS blastp result: AK243585 [KOME

    Lifescience Database Archive (English)

    Full Text Available n contains Pfam PF02365: No apical meristem (NAM) domain; No apical meristem gene (NAM), required for pattern formation in embryos and flowers-Petunia hybrida, PATCHX:E205713 6e-18 ...

  2. Arabidopsis CDS blastp result: AK287666 [KOME

    Lifescience Database Archive (English)

    Full Text Available n contains Pfam PF02365: No apical meristem (NAM) domain; No apical meristem gene (NAM), required for pattern formation in embryos and flowers-Petunia hybrida, PATCHX:E205713 1e-40 ...

  3. Arabidopsis CDS blastp result: AK287632 [KOME

    Lifescience Database Archive (English)

    Full Text Available n contains Pfam PF02365: No apical meristem (NAM) domain; No apical meristem gene (NAM), required for pattern formation in embryos and flowers-Petunia hybrida, PATCHX:E205713 5e-11 ...

  4. Arabidopsis CDS blastp result: AK243244 [KOME

    Lifescience Database Archive (English)

    Full Text Available n contains Pfam PF02365: No apical meristem (NAM) domain; No apical meristem gene (NAM), required for pattern formation in embryos and flowers-Petunia hybrida, PATCHX:E205713 2e-26 ...

  5. Reference: 623 [Arabidopsis Phenome Database[Archive

    Lifescience Database Archive (English)

    Full Text Available the molecular mechanisms that control growth of apical meristems have been widely studied (reviewed in). In contrast, much less atte...ntion has been paid to vascular meristems, such as the c

  6. Fulltext PDF

    Indian Academy of Sciences (India)

    Unknown

    meristem from a primordium have been identified, but a discussion of these floral meristem identity genes is beyond the scope ... between the floral induction pathways and the regulation of floral meristem identity genes are not well understood. 3. ... dopsis ecotypes from ancestral late-flowering types. FLC is a second gene ...

  7. Embryo-patterning genes and reinforcement cues determine cell fate in the Arabidopsis thaliana root

    NARCIS (Netherlands)

    Scheres, B.J.G.

    1996-01-01

    The majority of plant organs arise from groups of continuously dividing cells, the meristems. Little is known about mechanisms of cell specification in meristems. Within the Arabidopsis root meristem, the fate of every cell can be predicted accurately, and the origin of these cells during the

  8. Linking leaf initiation to the aerial environment: when air temperature is not the whole story

    NARCIS (Netherlands)

    Savvides, A.

    2014-01-01

    The initiation of new leaves, which takes place at the shoot apical meristem, is essential for plant growth and development. Leaf initiation rate (LIR) is very sensitive to meristem temperature. However, in practice meristem temperature is hardly ever monitored and air temperature is often used

  9. VFL, the Grapevine FLORICAULA/LEAFY Ortholog, Is Expressed in Meristematic Regions Independently of Their Fate1

    Science.gov (United States)

    Carmona, María José; Cubas, Pilar; Martínez-Zapater, José M.

    2002-01-01

    The flowering process in grapevine (Vitis vinifera) takes place in buds and extends for two consecutive growing seasons. To understand the genetic and molecular mechanisms underlying this process, we have characterized grapevine bud development, cloned the grapevine FLORICAULA/LEAFY (FLO/LFY) ortholog, VFL, and analyzed its expression patterns during vegetative and reproductive development. Flowering induction takes place during the first season. Upon induction, the shoot apical meristem begins to produce lateral meristems that will give rise to either inflorescences or tendrils. During the second season, after a winter dormancy period, buds reactivate and inflorescence meristems give rise to flower meristems. VFL is expressed in lateral meristems that give rise to inflorescence and flower meristems, consistent with a role in reproductive development. Furthermore, VFL is also detected in other meristematic regions such as the vegetative shoot apical meristem and the lateral meristems that will give rise to tendrils. VFL is also expressed in leaf primordia and in growing leaf margins until later stages of development. Accumulation of VFL transcripts in cell-proliferating regions suggests a role for VFL not only in flower meristem specification, but also in the maintenance of indeterminacy before the differentiation of derivatives of the apical meristem: flowers, leaves, or tendrils. PMID:12226487

  10. Irradiation damage and recovery in shoot apices of sweet cherry (Prunus avium L.)

    International Nuclear Information System (INIS)

    Saamin, S.; Thompson, M.M.

    1990-01-01

    Full text: Dormant scions of 'Bing' were exposed to fractionated 6kR gamma rays and then grafted. Irradiated and unirradiated main buds were sampled at 3 day intervals for one month. Buds were fixed in FAA, longitudinally sectioned, and stained with hematoxylin. Both random and localised cell damage was observed in irradiated apices. There was evidence of radiosensitivity gradient in the shoot apex. Recovery from irradiation damage was via flank meristem, central meristem, or leaf primordia and axillary meristems. (author)

  11. The Mutation Frequency in Different Spike Categories in Barley

    DEFF Research Database (Denmark)

    Frydenberg, O.; Doll, Hans; Sandfær, J.

    1964-01-01

    After gamma irradiation of barley seeds, a comparison has been made between the chlorophyll-mutant frequencies in X1 spikes that had multicellular bud meristems in the seeds at the time of treatment (denoted as pre-formed spikes) and X1 spikes having no recognizable meristems at the time...

  12. Roots redefined: anatomical and genetic analysis of root development

    NARCIS (Netherlands)

    Scheres, B.J.G.; McKahnn, H.; Berg, C. van den

    1996-01-01

    The postembryonic development of plants is fueled by apical meristems, which are the local production sites of new cells that form a pattern of different cell types within an organ. The regularity of this pattern in the root yielded ideas on its formation from the meristem well before critical

  13. Restorative Commons: Creating Health and Well-Being Through Urban Landscapes

    Science.gov (United States)

    Lindsay Campbell; Anne Wiesen

    2009-01-01

    A collection of 18 articles inspired by the Meristem 2007 Forum, "Restorative Commons for Community Health." The articles include interviews, case studies, thought pieces, and interdisciplinary theoretical works that explore the relationship between human health and the urban environment. This volume is a joint endeavor of Meristem and the U.S. Forest Service...

  14. Repression of AGAMOUS-LIKE 24 is a crucial step in promoting flower development.

    Science.gov (United States)

    Yu, Hao; Ito, Toshiro; Wellmer, Frank; Meyerowitz, Elliot M

    2004-02-01

    Flower development begins as floral meristems arise in succession on the flank of the inflorescence meristem. Floral meristem identity genes LEAFY (LFY) and APETALA1 (AP1) promote establishment and maintenance of floral identity in newly formed floral primordia. Without their activity, the floral primordia develop with inflorescence characteristics. The underlying molecular-genetic mechanism is unknown. Here we show that these phenotypes are due in large part to the ectopic expression of AGAMOUS-LIKE 24 (AGL24), a central regulator of floral meristem identity. We present evidence that AGL24 is an early target of transcriptional repression by LFY and AP1. Without such repression, continued AGL24 expression in floral meristems is sufficient to cause floral reversion regardless of the activation of floral organ identity genes. This indicates that LFY and AP1 promote floral development not only by positively regulating genes activated in flower development, but also by repressing AGL24, a promoter of inflorescence fate.

  15. Transition zone cells reach G2 phase before initiating elongation in maize root apex

    Directory of Open Access Journals (Sweden)

    M. Victoria Alarcón

    2017-06-01

    Full Text Available Root elongation requires cell divisions in the meristematic zone and cell elongation in the elongation zone. The boundary between dividing and elongating cells is called the transition zone. In the meristem zone, initial cells are continuously dividing, but on the basal side of the meristem cells exit the meristem through the transition zone and enter in the elongation zone, where they stop division and rapidly elongate. Throughout this journey cells are accompanied by changes in cell cycle progression. Flow cytometry analysis showed that meristematic cells are in cycle, but exit when they enter the elongation zone. In addition, the percentage of cells in G2 phase (4C strongly increased from the meristem to the elongation zone. However, we did not observe remarkable changes in the percentage of cells in cell cycle phases along the entire elongation zone. These results suggest that meristematic cells in maize root apex stop the cell cycle in G2 phase after leaving the meristem.

  16. Citotoxicity of food dyes sunset yellow (E-110, bordeaux red (E-123, and tatrazine yellow (E-102 on Allium cepa L. root meristematic cells Citotoxicidade dos corantes alimentares amarelo crepúsculo (E-110, vermelho bordeaux (E-123 e amarelo tartrazina (E-102 em células meristemáticas de raízes de Allium cepa L.

    Directory of Open Access Journals (Sweden)

    Keiva Maria Silva Gomes

    2013-03-01

    Full Text Available The objective of this study was to evaluate the cytotoxic effect of the food dyes sunset yellow, bordeaux red, and tartrazine yellow on the cellular cycle of Allium cepa L. Each dye was evaluated at the doses of 0.4 and 4.0 mL, at the exposure times of 24 and 48 hours in root tip cells of Allium cepa L. Slides were prepared and cells were analyzed during the whole cell cycle for cellular aberrations totaling 5,000 total cells for each dose evaluated. The mitotic index was calculated, and statistical analysis was performed using the Chi-squared test (p Este estudo teve por objetivo avaliar o efeito citotóxico dos corantes alimentares amarelo crepúsculo, vermelho bordeaux e amarelo tartrazina sobre o ciclo celular de Allium cepa L. Cada corante foi avaliado nas doses de 0,4 e 4,0 mL, nos tempos de exposição de 24 e 48 horas, em células de pontas de raízes de Allium cepa L. Prepararam-se lâminas e analisaram-se células, em todo o ciclo celular, e a presença de aberrações celulares, totalizando 5.000 células para cada dose avaliada. Foi calculado o índice mitótico e a análise estatística foi feita por meio do teste quiquadrado (p < 0,05. Os resultados mostraram que os três corantes, nas doses e tempos de exposição avaliados, foram citotóxicos às células do sistema-teste utilizado. Estudos adicionais de citotoxicidade devem ser conduzidos para se somar a estes resultados e, assim, avaliar, com propriedade, a ação destes três corantes em nível celular.

  17. Primary root protophloem differentiation requires balanced phosphatidylinositol-4,5-biphosphate levels and systemically affects root branching.

    NARCIS (Netherlands)

    Rodriguez-Villalon, A.; Gujas, B.; van Wijk, R.; Munnik, T.; Hardtke, C.S.

    2015-01-01

    Protophloem is a specialized vascular tissue in growing plant organs, such as root meristems. In Arabidopsis mutants with impaired primary root protophloem differentiation, brevis radix (brx) and octopus (ops), meristematic activity and consequently overall root growth are strongly reduced. Second

  18. From front yards to street corners: revitalizing neighborhoods through community-based land stewardship

    Science.gov (United States)

    Colleen Murphy-Dunning

    2009-01-01

    One of 18 articles inspired by the Meristem 2007 Forum, "Restorative Commons for Community Health." The articles include interviews, case studies, thought pieces, and interdisciplinary theoretical works that explore the relationship between human health and the urban...

  19. Re-naturing the city: a role for sustainable infrastructure and buildings

    Science.gov (United States)

    Hillary Brown

    2009-01-01

    One of 18 articles inspired by the Meristem 2007 Forum, "Restorative Commons for Community Health." The articles include interviews, case studies, thought pieces, and interdisciplinary theoretical works that explore the relationship between human health and the urban...

  20. Plantlet regeneration potential from seedling explants of vitegnus (Vitex agnus castus).

    Science.gov (United States)

    Chamandoosti, F

    2007-11-15

    In this research a simple and repeatable method for regeneration of a important medicinal plant (Vitex agnus castus) described. Different seedling explants such as hypocotyl, cotyledon, root and apical meristem were cultured in MS basal media with different kinds and concentrations of PGRs. Root and apical meristem explants were the only explants that have regeneration whole plantlets potential. It was interesting that regeneration whole plantlets from root and apical meristem explants have different developmental pathways. Whole plantlets from apical meristem explants regenerated by passing phase callusing whereas regeneration whole plantlets from root was direct and without phase callusing. This subject implies that we can have many manipulation possibilities in order to different objects of tissue culture by selecting different explants in vitegnus.

  1. Combined impact of water column oxygen and temperature on internal oxygen status and growth of Zostera marina seedlings and adult shoots

    DEFF Research Database (Denmark)

    Raun, Ane-Marie Løvendahl; Borum, Jens

    2013-01-01

    at temperatures of ≥25°C. In the present study we experimentally examine the impact of combined water column oxygen and temperature on oxygen dynamics in leaf meristems of seedlings and adult shoots to better understand how stressful environmental conditions affect eelgrass oxygen dynamics and subsequent growth...... and mortality. There was a strong interaction between water column oxygen and temperature on meristem pO implying that eelgrass is rather resistant to unfavorable oxygen conditions in winter but becomes increasingly vulnerable in summer, especially at high temperatures. At 25°C meristems became anoxic...... were less prone to meristem anoxia than adult shoots suggesting that seedlings would better tolerate unfavorable combinations of water column oxygen conditions and temperature. The results suggest that eelgrass die-offs will occur more frequently in eutrophied coastal areas with the more frequent...

  2. Environmental and community health: a reciprocal relationship

    Science.gov (United States)

    Jeffery Sugarman

    2009-01-01

    One of 18 articles inspired by the Meristem 2007 Forum, "Restorative Commons for Community Health." The articles include interviews, case studies, thought pieces, and interdisciplinary theoretical works that explore the relationship between human health and the urban...

  3. Adapting the botanical garden into a sustainable, multicultural resource

    Science.gov (United States)

    Susan Lacerte

    2009-01-01

    One of 18 articles inspired by the Meristem 2007 Forum, "Restorative Commons for Community Health." The articles include interviews, case studies, thought pieces, and interdisciplinary theoretical works that explore the relationship between human health and the urban...

  4. Creative uncertainty

    Science.gov (United States)

    Victoria Marshall; Dil Hoda

    2009-01-01

    One of 18 articles inspired by the Meristem 2007 Forum, "Restorative Commons for Community Health." The articles include interviews, case studies, thought pieces, and interdisciplinary theoretical works that explore the relationship between human health and the urban...

  5. Cytokinin response factors regulate PIN-FORMED auxin transporters

    Czech Academy of Sciences Publication Activity Database

    Šimášková, M.; O'Brien, J.A.; Khan, M.; Van Noorden, G.; Ötvös, K.; Vieten, A.; De Clercq, E.; Van Haperen, J.M.A.; Cuesta, C.; Hoyerová, Klára; Vanneste, S.; Marhavý, P.; Wabnik, K.; Van Breusegem, F.; Nowack, M.; Murphy, A.; Friml, J.; Weijers, D.; Beeckman, T.; Benková, E.

    2015-01-01

    Roč. 6, NOV (2015), s. 8717 ISSN 2041-1723 Institutional support: RVO:61389030 Keywords : ARABIDOPSIS -THALIANA * ROOT-MERISTEM * TRANSCRIPTION FACTORS Subject RIV: ED - Physiology Impact factor: 11.329, year: 2015

  6. The benefits of community-managed open space: community gardening in New York City

    Science.gov (United States)

    Edie Stone

    2009-01-01

    One of 18 articles inspired by the Meristem 2007 Forum, "Restorative Commons for Community Health." The articles include interviews, case studies, thought pieces, and interdisciplinary theoretical works that explore the relationship between human health and the urban...

  7. Urban gardens: catalysts for restorative commons infrastructure

    Science.gov (United States)

    John Seitz

    2009-01-01

    One of 18 articles inspired by the Meristem 2007 Forum, "Restorative Commons for Community Health." The articles include interviews, case studies, thought pieces, and interdisciplinary theoretical works that explore the relationship between human health and the urban...

  8. Reference: 164 [Arabidopsis Phenome Database[Archive

    Lifescience Database Archive (English)

    Full Text Available cture continuously producing cells that become incorporated into new leaves, stems and flowers. The maintena...largement of inflorescence and floral meristems, the production of supernumerary flowers and floral organs,

  9. Biophilia, health, and well-being

    Science.gov (United States)

    Judith Heerwagen

    2009-01-01

    One of 18 articles inspired by the Meristem 2007 Forum, "Restorative Commons for Community Health." The articles include interviews, case studies, thought pieces, and interdisciplinary theoretical works that explore the relationship between human health and the urban...

  10. Landscape designers, doctors, and the making of healthy urban spaces in 19th century America

    Science.gov (United States)

    Robert Martensen

    2009-01-01

    One of 18 articles inspired by the Meristem 2007 Forum, "Restorative Commons for Community Health." The articles include interviews, case studies, thought pieces, and interdisciplinary theoretical works that explore the relationship between human health and the urban...

  11. Youth empowerment through urban agriculture: Red Hook Community Farm

    Science.gov (United States)

    Ian Marvy

    2009-01-01

    One of 18 articles inspired by the Meristem 2007 Forum, "Restorative Commons for Community Health." The articles include interviews, case studies, thought pieces, and interdisciplinary theoretical works that explore the relationship between human health and the urban...

  12. Micropropagation of Plectranthus edulis (Vatke) Agnew from ...

    African Journals Online (AJOL)

    SAM

    2014-09-03

    Bryan, 1983). The application of plant tissue culture offers valuable ways to overcome many of the problems that are encountered in natural propagation. Meristem culture can be used alone or in combination with thermotherapy ...

  13. Creating restorative settings: inclusive design considerations

    Science.gov (United States)

    David Kamp

    2009-01-01

    One of 18 articles inspired by the Meristem 2007 Forum, "Restorative Commons for Community Health." The articles include interviews, case studies, thought pieces, and interdisciplinary theoretical works that explore the relationship between human health and the urban...

  14. Reference: 292 [Arabidopsis Phenome Database[Archive

    Lifescience Database Archive (English)

    Full Text Available ular and hormonal phenotype, we propose a role for WOX5 in the root apical meristem as a negative trigger of IAA homeostatic mechanis...ms allowing the maintenance of a restricted area of auxi

  15. CLE/RLK regulated vascular signalling pathways in plants

    OpenAIRE

    Kücükoglu, Melis

    2009-01-01

    Entire postembryonic production of plant tissues are maintained by meristems. These specialized structures provide a pool of undifferentiated stem cells and a limited population of proliferating cells which are destined for differentiation in order to generate a variety of tissues in the plant body. For the forest trees, a large part of the biomass is produced by a secondary meristem called vascular cambium. Vascular cambium forms a continuous cylinder of meristematic cells in the stem, produ...

  16. The sweet cherry (Prunus avium) FLOWERING LOCUS T gene is expressed during floral bud determination and can promote flowering in a winter-annual Arabidopsis accession.

    Science.gov (United States)

    Yarur, Antonia; Soto, Esteban; León, Gabriel; Almeida, Andrea Miyasaka

    2016-12-01

    FT gene is expressed in leaves and buds and is involved in floral meristem determination and bud development in sweet cherry. In woody fruit perennial trees, floral determination, dormancy and bloom, depends on perception of different environmental and endogenous cues which converge to a systemic signaling gene known as FLOWERING LOCUS T (FT). In long-day flowering plants, FT is expressed in the leaves on long days. The protein travels through the phloem to the shoot apical meristem, where it induces flower determination. In perennial plants, meristem determination and flowering are separated by a dormancy period. Meristem determination takes place in summer, but flowering occurs only after a dormancy period and cold accumulation during winter. The roles of FT are not completely clear in meristem determination, dormancy release, and flowering in perennial plants. We cloned FT from sweet cherry (Prunus avium) and analyzed its expression pattern in leaves and floral buds during spring and summer. Phylogenetic analysis shows high identity of the FT cloned sequence with orthologous genes from other Rosaceae species. Our results show that FT is expressed in both leaves and floral buds and increases when the daylight reached 12 h. The peak in FT expression was coincident with floral meristem identity genes expression and morphological changes typical of floral meristem determination. The Edi-0 Arabidopsis ecotype, which requires vernalization to flower, was transformed with a construct for overexpression of PavFT. These transgenic plants showed an early-flowering phenotype without cold treatment. Our results suggest that FT is involved in floral meristem determination and bud development in sweet cherry. Moreover, we show that FT is expressed in both leaves and floral buds in this species, in contrast to annual plants.

  17. Effects of Osmolytic Agents on Somatic Embryogenesis of Saffron (Crocus sativus L.

    Directory of Open Access Journals (Sweden)

    Maryam VAHEDI

    2015-03-01

    Full Text Available A protocol for callus induction from meristem tissues and subsequent somatic embryo formation were established in this study. Explants were taken from apical and lateral meristems of saffron and these explants were cultured on MS medium supplemented with combinations of 2.4-dichlorophenoxyacetic acid (2.4-D and Kinetin (Kn. The effects of osmotic agents such as abscisic acid (ABA, polyethylene glycol (PEG and Gelrite on somatic embryogenesis were also investigated. After 45 and 60 days of culture, calli were induced from apical and lateral meristems, respectively. The apical meristems yielded higher quality calli when compared to the lateral meristems. The highest frequency of callogenesis and the growth rate of callus were achieved from apical meristems on Murashige and Skoogs (MS medium supplemented with 2.4-D (2 mg/l and Kinetin (0.5 mg/l. After 45 days of subculture, the segments of nodular calli were transferred to plant growth regulator (PGR- free media for induction of pre-embryogenesis embryo formation. Pre-matured embryos were cultured on MS medium supplemented with different osmotic agents such as Gelrite, ABA and PEG to study their effects on embryo maturation. Both PEG and ABA proved more effective for somatic embryo maturation as compared to Gelrite.

  18. Effects of Osmolytic Agents on Somatic Embryogenesis of Saffron (Crocus sativus L.

    Directory of Open Access Journals (Sweden)

    Maryam VAHEDI

    2015-03-01

    Full Text Available A protocol for callus induction from meristem tissues and subsequent somatic embryo formation were established in this study. Explants were taken from apical and lateral meristems of saffron and these explants were cultured on MS medium supplemented with combinations of 2.4-dichlorophenoxyacetic acid (2.4-D and Kinetin (Kn. The effects of osmotic agents such as abscisic acid (ABA, polyethylene glycol (PEG and Gelrite on somatic embryogenesis were also investigated. After 45 and 60 days of culture, calli were induced from apical and lateral meristems, respectively. The apical meristems yielded higher quality calli when compared to the lateral meristems. The highest frequency of callogenesis and the growth rate of callus were achieved from apical meristems on Murashige and Skoogs (MS medium supplemented with 2.4-D (2 mg/l and Kinetin (0.5 mg/l. After 45 days of subculture, the segments of nodular calli were transferred to plant growth regulator (PGR- free media for induction of pre-embryogenesis embryo formation. Pre-matured embryos were cultured on MS medium supplemented with different osmotic agents such as Gelrite, ABA and PEG to study their effects on embryo maturation. Both PEG and ABA proved more effective for somatic embryo maturation as compared to Gelrite.

  19. RESERVAS ORGÂNICAS, RELAÇÃO PARTE AÉREA–RAIZ E C–N E ELIMINAÇÃO DO MERISTEMA APICAL NO CAPIM-XARAÉS SOB DOSES DE NITROGÊNIO E POTÁSSIO ORGANIC RESERVES, AEREAL PART:ROOT AND C:N RATIO AND ELIMINATION OF THE APICAL MERISTEM IN XARAÉS – GRASS UNDER NITROGEN AND POTASSIUM DOSIS

    Directory of Open Access Journals (Sweden)

    Amaury Camilo Valinote

    2007-09-01

    Full Text Available

    como a capacidade de recuperação das plantas for-rageiras após desfolha depende, dentre outros fatores, das reservas orgânicas e da área foliar remanescente, objetivou-se com este estudo quantificar os teores de carboidratos totais não-estruturais (cTnE e de n total, nas raízes, base do caule e coroa, determinar a relação parte aérea–raiz e c–n e eliminação do meristema apical no capim-Xaraés (Brachiaria brizantha cv. Xaraés, submetido a doses de nitrogênio e potássio. O experimento foi desenvolvido em casa-de-vegetação, empregando-se um esquema fatorial 4 x 3, perfazendo doze combinações. Utilizaram-se quatro doses de nitrogênio (0, 75, 150 e 225 mg dm-3 e três do-ses de potássio (0, 50 e 100 mg dm-3. Observou-se efeito (P<0,05 das doses de nitrogênio no aumento dos teores de n total e da produção de MS da base do caule e raiz e redução dos teores de cTnE, sendo as raízes o órgão de armazenamento. Houve interação (P<0,05 para as doses de n x K na relação c–n para todos os órgãos, reduzindo com o aumento das doses dos nutrientes e com a elevação nos teores de n total na coroa com o aumento das doses. A relação parte aérea–raiz e eliminação do meristema apical não sofreu efeito (P>0,05 de nenhum nutriente.

    PALAVRAS-CHAVES: Base do caule, Brachiaria brizantha, coroa, n-total, carboidratos totais não-estruturais, raiz.

    The capacity of recovery of plants after takes away the leaves, depends amongst other factors, of the organic reserves and the remaining foliar area. It was objectified with this study, to quantify meaning of non-structural total carbohydrates (Tnc and of total n, in the roots, base of stem and crown, to determine the relation has broken ae-rial/root and c/n and elimination of meristema apical in the Xaraés Grass (Brachiaria brizantha cv. Xaraés, submitted the rates of nitrogen and potassium. The experiment was lead in a greenhouse. The experimental treatments have consisted on a 4X3 combination. The nitrogen rates were 0; 75; 150 and 225 mg dm-3, whereas potassium rates were 0; 50 and 100 mg dm-3. Effect (P<0,05 of the rates of nitrogen in the increase of meaning of total n and the production of DM of the base of stem and root and reduction of Tnc meaning was observed, in the same ones, being the roots the storage organ. It had interaction (P<0.05 for the doses of n x K in relation c/n for all the organs reducing with the increase of the rates of the nutrients and rise in meaning of total n in the crown with the increase of the doses. The relation has broken aerial/root and elimination of meristema apical did not suffer effect (P>0.05 from no nutrient.

    KEY-WORDS: Brachiaria brizantha, crown, total n, total nonstructural carbohydrates, roots, stem base.

  20. Induced mutation and radiation sensitivity in vitro culture of soybean (Glycine Max L. Merrill)

    International Nuclear Information System (INIS)

    Atak, C.; Alikamanoglu, S.; Yalcin, S.

    1999-01-01

    In our research, the seeds of J-357 soybean variety were irradiated with 50, 100, 200, 300 and 500 Gy of gamma rays. Callus and meristem cultures were established from the primary leaves and apical meristem of 5-day-old seeding from the irradiation seeds. The average callus fresh weight formed at the cultures were determined on the 30th day and GR 50 dose which reduces the callus fresh weight at the rate 50% in accordance with control was found as 250 Gy. The regenerated plants from meristem cultures were determined on the 28th day and LD 50 dose which decreases the regenerated plant percentage at the 50% in accordance with control was found as 220 Gy. Cytological investigation was done at the callus and meristem cultures obtained from both irradiated seeds and explants. At the seed and explant irradiations, gamma radiation dose between the ranges 50 to 200 Gy and 5 to 25 Gy; respectively were used. Observations were done at mitotic anaphase in the samples taken from meristem and callus cultures. In anaphase, two types of cytological aberrations, bridge and fragments were determined. The regenerated plants were grown in the climate chamber and the seeds were taken from each M1 plant and chlorophyll mutants were determined in M2 generation. The radiosensitivity of the meristem cultures established by irradiated seeds from view of plant regenerations and plant number which is taken seed was evaluated by comparing with the results of meristem cultures established from the irradiated explant from the point of in vitro mutation studies

  1. Characterization and expression analysis of TERMINAL FLOWER1 homologs from cultivated alloteraploid cotton (Gossypium hirsutum) and its diploid progenitors.

    Science.gov (United States)

    Argiriou, Anagnostis; Michailidis, Georgios; Tsaftaris, Athanasios S

    2008-10-09

    The seasonal cycle and persistence of a plant is governed by a combination of the determinate or indeterminate status of shoot and root apical meristems. A perennial plant is one in which the apical meristem of at least one of its shoot axes remains indeterminate beyond the first growth season. TERMINAL FLOWER1 (TFL1) genes play important roles in regulating flowering time, the fate of inflorescence meristem and perenniality. To investigate the role of TFL1-like genes in the determination of the apical meristems in an industrially important crop cultivated for its fibers, we isolated and characterized two TFL1 homologs (TFL1a and TFL1b) from tetraploid cultivated cotton (Gossypium hirsutum) and its diploid progenitors (Gossypium arboreum and Gossypium raimondii). All isolated genes maintain the same exon-intron organization. Their phylogenetic analysis at the amino acid level confirmed that the isolated sequences are TFL1-like genes and collocate in the TFL1 clade of the PEBP protein family. Expression analysis revealed that the genes TFL1a and TFL1b have slightly different expression patterns, suggesting different functional roles in the determination of the meristems. Additionally, promoter analysis by computational methods revealed the presence of common binding motifs in TFL1-like promoters. These are the first reported TFL1-like genes isolated from cotton, the most important crop for the textile industry.

  2. Leaf ontogeny of Schinus molle L. plants under cadmium contamination: the meristematic origin of leaf structural changes.

    Science.gov (United States)

    Pereira, Marcio Paulo; Corrêa, Felipe Fogaroli; de Castro, Evaristo Mauro; de Oliveira, Jean Paulo Vitor; Pereira, Fabricio José

    2017-11-01

    Previous works show the development of thicker leaves on tolerant plants growing under cadmium (Cd 2+ ) contamination. The aim of this study was to evaluate the Cd 2+ effects on the leaf meristems of the tolerant species Schinus molle. Plants were grown in nutrient solution containing 0, 10, and 50 μM of Cd 2+ . Anatomical analysis was performed on leaf primordia sampled at regular time intervals. Under the lowest Cd 2+ level (10 μM), increased ground meristem thickness, diameter of the cells, cell elongation rate, and leaf dry mass were found. However, 50 μM of Cd 2+ reduced all these variables. In addition, the ground meristem cells became larger when exposed to any Cd 2+ level. The epidermis, palisade parenchyma, and vascular tissues developed earlier in Cd 2+ -exposed leaves. The modifications found on the ground meristem may be related to the development of thicker leaves on S. molle plants exposed to low Cd 2+ levels. Furthermore, older leaves showed higher Cd 2+ content when compared to the younger ones, preventing the Cd 2+ toxicity to these leaves. Thus, low Cd 2+ concentrations change the ground meristem structure and function reflecting on the development of thicker and enhanced leaves.

  3. Low temperature treatment affects concentration and distribution of chrysanthemum stunt viroid in Argyranthemum

    Directory of Open Access Journals (Sweden)

    Zhibo eZhang

    2016-03-01

    Full Text Available Chrysanthemum stunt viroid (CSVd can infect Argyranthemum and cause serious economic loss. Low temperature treatment combined with meristem culture has been applied to eradicate viroids from their hosts, but without success in eliminating CSVd from diseased Argyranthemum. The objectives of this work were to investigate 1 the effect of low temperature treatment combined with meristem culture on elimination of CSVd, 2 the effect of low temperature treatment on CSVd distribution pattern in shoot apical meristem (SAM, and 3 CSVd distribution in flowers and stems of two infected Argyranthemum cultivars. After treatment with low temperature combined with meristem tip culture, two CSVd-free plants were found in ‘Border Dark Red’, but none in ‘Yellow Empire’. With the help of in situ hybridization, we found that CSVd distribution patterns in the SAM showed no changes in diseased ‘Yellow Empire’ following 5oC treatment, compared with non-treated plants. However, the CSVd-free area in SAM was enlarged in diseased ‘Border Dark Red’ following prolonged 5oC treatment. Localization of CSVd in the flowers and stems of infected ‘Border Dark Red’ and ‘Yellow Empire’ indicated that seeds could not transmit CSVd in these two cultivars, and CSVd existed in phloem. Results obtained in the study contributed to better understanding of the distribution of CSVd in systemically infected plants and the combination of low temperature treatment and meristem tip culture for production of viroid-free plants.

  4. Response to auxin changes during maturation-related loss of adventitious rooting competence in loblolly pine (Pinus taeda) stem cuttings.

    Science.gov (United States)

    Greenwood, Michael S.; Cui, Xiuyu; Xu, Fuyu

    2001-03-01

    Hypocotyl cuttings (from 20- and 50-day-old Pinus taeda L. seedlings) rooted readily within 30 days in response to exogenous auxin, while epicotyl cuttings (from 50-day-old seedlings) rarely formed roots within 60 days. Responses to auxin during adventitious rooting included the induction of cell reorganization and cell division, followed by the organization of the root meristem. Explants from the bases of both epicotyl and hypocotyl cuttings readily formed callus tissue in response to a variety of auxins, but did not organize root meristems. Auxin-induced cell division was observed in the cambial region within 4 days, and later spread to the outer cortex at the same rate in both tissues. Cells at locations that would normally form roots in foliated hypocotyl cuttings did not produce callus any differently than those in other parts of the cortex. Therefore, auxin-induced root meristem organization appeared to occur independently of auxin-induced cell reorganization/division. The observation that N-(1-naphthyl)phthalamic acid (NPA) promoted cellular reorganization and callus formation but delayed rooting implies the existence of an auxin signal transduction pathway that is specific to root meristem organization. Attempts to induce root formation in callus or explants without foliage were unsuccessful. Both the cotyledon and epicotyl foliage provided a light-dependent product other than auxin that promoted root meristem formation in hypocotyl cuttings.

  5. Developmental morphology of branching flowers in Nymphaea prolifera.

    Science.gov (United States)

    Grob, Valentin; Moline, Philip; Pfeifer, Evelin; Novelo, Alejandro R; Rutishauser, Rolf

    2006-11-01

    Nymphaea and Nuphar (Nymphaeaceae) share an extra-axillary mode of floral inception in the shoot apical meristem (SAM). Some leaf sites along the ontogenetic spiral are occupied by floral primordia lacking a subtending bract. This pattern of flower initiation in leaf sites is repeated inside branching flowers of Nymphaea prolifera (Central and South America). Instead of fertile flowers this species usually produces sterile tuberiferous flowers that act as vegetative propagules. N. prolifera changes the meristem identity from reproductive to vegetative or vice versa repeatedly. Each branching flower first produces some perianth-like leaves, then it switches back to the vegetative meristem identity of the SAM with the formation of foliage leaves and another set of branching flowers. This process is repeated up to three times giving rise to more than 100 vegetative propagules. The developmental morphology of the branching flowers of N. prolifera is described using both microtome sections and scanning electron microscopy.

  6. Radiation damage and induced tetraploidy in mulberry (Morus alba L.)

    International Nuclear Information System (INIS)

    Katagiri, K.

    1976-01-01

    Vigorously growing mulberry shoots were exposed to 5 kR of gamma rays at the rate of 0.2 kR/hr and 5.0 kR/hr and successively pruned three times in two growing seasons. The most radiosensitive part of both the apical and axillary meristems was the second cell layer. The younger axillary bud primordia were more sensitive to radiation then the older ones. Recovery from radiation damage was assumed to be from the flank meristem in the shoot apex. The frequency of mutations was much lower than that of tetraploidy. Among the tetraploids 50% were 2-4-4 chimeras. (author)

  7. Exploring the African cassava (Manihot esculenta Crantz ...

    African Journals Online (AJOL)

    Somatic-embryogenic competence of eleven cassava genotypes was determined in induction media containing 8 and 12 mg/l of the auxin picloram, using axillary meristems and leaf lobes as explants. There were significant differences (p<0.01) among the cassava genotypes for ability to form somatic embryos. Proembryo ...

  8. Micropropagation of Plectranthus edulis (Vatke) Agnew from ...

    African Journals Online (AJOL)

    Plectranthus edulis (Vatke) Agnew is a tuber-bearing food crop in Ethiopia. However, its productivity is hampered by shortage of pathogen-free planting materials. Therefore, the objective of this study was to develop micropropagation protocol for this plant using meristem to produce clean planting materials. Mersitems were ...

  9. Detection of somaclonal variation in micropropagated Hibiscus ...

    African Journals Online (AJOL)

    The main objective of micropropagation is to produce clones i.e. plants which are phenotypically and genetically identical to the mother plants. The culture of organized meristems usually guarantees the production of true-to-type plants but variations in the progenies have been widely reported. Hibiscus sabdariffa L. plants ...

  10. Transcriptional control of secondary growth and wood formation.

    Science.gov (United States)

    Juan Du; Andrew Groover

    2010-01-01

    Secondary growth and wood formation are products of the vascular cambium, a lateral meristem. Although the mechanisms have only recently begun to be uncovered, transcriptional regulation appears increasingly central to the regulation of secondary growth. The importance of transcriptional regulation is illustrated by the correlation of expression of specific classes of...

  11. Caulimoviral sequences in Dahlia variabilis in Egypt

    African Journals Online (AJOL)

    Jane

    NZ (isolated from New Zealand dahlia cultivars), D10-DC (isolated from D. coccinea) and D10-Egypt. (isolated from Egyptian dahlia cultivars) in one clade. Key words: Dahlia variabilis, .... Additionally, tools such as meristem tip culture used for virus elimination are ineffective in virally- integrated genomes such as BSV ...

  12. Herbivory OF hydrilla verticillata by Cichlid fish in Lake Bisina, Uganda

    African Journals Online (AJOL)

    The aquatic macrophyte, Hydrilla verticillata is a serious invasive plant in many countries. In East and Central Africa, H. verticillata is present in some water bodies, but not considered a weed. Hydrilla verticillata leaves collected in this region often appear to be chewed, and many stems are missing their apical meristems.

  13. Phyllotaxis

    NARCIS (Netherlands)

    Weijers, Dolf

    2016-01-01

    Local auxin concentration maxima promote organ initiation in the plant shoot meristem, but how auxin peaks are formed has remained unclear. A new study proposes a cellular Matthew effect, where auxin is pumped into those cells that have higher concentrations.

  14. Characterization and fine mapping of a female fertility associated ...

    Indian Academy of Sciences (India)

    2015-03-12

    Mar 12, 2015 ... loid biosynthesis, including synthesis of nicotine, nornico- tine, anabasine, and anatabine (Häkkinen et al. 2007). In addition, LOG, annotated as LDC, was verified to be required to maintain meristem activity. Also, LOG did not exhibit lysine decarboxylase activity (Kurakawa et al. 2007). Rice ovary consists ...

  15. Patterning of Inflorescences and Flowers by the F-Box Protein DOUBLE TOP and the LEAFY Homolog ABERRANT LEAF AND FLOWER of Petunia.

    NARCIS (Netherlands)

    Souer, E.J.; Bliek, M.; Koes, R.E.; Kusters, E.; Bruin de, R.A.

    2008-01-01

    Angiosperms display a wide variety of inflorescence architectures differing in the positions where flowers or branches arise. The expression of floral meristem identity (FMI) genes determines when and where flowers are formed. In Arabidopsis thaliana, this is regulated via transcription of LEAFY

  16. Changes in cis-regulatory elements of a key floral regulator are associated with divergence of inflorescence architectures

    NARCIS (Netherlands)

    Kusters, E.; Della Pina, S.; Castel, R.; Souer, E.; Koes, R.

    2015-01-01

    Higher plant species diverged extensively with regard to the moment (flowering time) and position (inflorescence architecture) at which flowers are formed. This seems largely caused by variation in the expression patterns of conserved genes that specify floral meristem identity (FMI), rather than

  17. Changes in cis-regulatory elements of a key floral regulator are associated with divergence of inflorescence architectures.

    NARCIS (Netherlands)

    Kusters, E.; Della Pina, S.; Castel, R.; Souer, E.J.; Koes, R.E.

    2015-01-01

    Higher plant species diverged extensively with regard to the moment (flowering time) and position (inflorescence architecture) at which flowers are formed. This seems largely caused by variation in the expression patterns of conserved genes that specify floral meristem identity (FMI), rather than

  18. Electric current affects the rate of development in isolated apical parts of rape in vitro

    Czech Academy of Sciences Publication Activity Database

    Filek, M.; Koscielniak, J.; Marcińska, I.; Krekule, Jan; Macháčková, Ivana; Dubert, F.

    2006-01-01

    Roč. 50, č. 3 (2006), s. 465-468 ISSN 0006-3134 Institutional research plan: CEZ:AV0Z5038910 Keywords : apical meristem differentiation * flowering factors * vernalization Subject RIV: EF - Botanics Impact factor: 1.198, year: 2006

  19. USE OF CELL ENGINEERING FOR DEVELOPMENT OF THE CONSTANT INITIAL BREEDING MATERIAL OF WHITE HEAD CABBAGE CV. NADZEJA AND CMS SAMPLES

    Directory of Open Access Journals (Sweden)

    A. V. Yakimovich

    2013-01-01

    Full Text Available The anther derived androgenic plants of white head cabbage cv. Nadzeja and CMS samples were obtained. The cytological analysis of ploidy level of regenerated plants and doubled haploids obtained by treatment of meristems with colchicine was performed. On the basis of androgenic doubled hap loids of white head cabbage genotypes the seed plants were developed.

  20. SHORT-ROOT and SCARECROW regulate leaf growth in Arabidopsis by stimulating S-phase progression of the cell cycle.

    NARCIS (Netherlands)

    S. Dhondt; F. Coppens; F. de Winter; K. Swarup; R.M.H. Merks (Roeland); D. Inze; M.J. Bennett; G.T.S. Beemster

    2010-01-01

    htmlabstractSHORT-ROOT (SHR) and SCARECROW (SCR) are required for stem cell maintenance in the Arabidopsis (Arabidopsis thaliana) root meristem, ensuring its indeterminate growth. Mutation of SHR and SCR genes results in disorganization of the quiescent center and loss of stem cell activity,

  1. Control of plant virus diseases in sub-Saharan Africa: the possibility ...

    African Journals Online (AJOL)

    Plant viruses and virus diseases have been studied for more than 100 years and much attention has been given to their control. However, this has been difficult to achieve because of the lack of any effective means of curing virus-infected plants. Chemotherapy, thermotherapy and meristem-tip culture can be successful, but ...

  2. Dt2 is a gain-of-function MADS-Domain factor gene that controls semi-determinacy in soybean

    Science.gov (United States)

    Similar to Arabidopsis, the wild soybean (Glycine soja) and many soybean (Glycine max) cultivars exhibit indeterminate stem growth controlled by a gene Dt1 – the functional counterpart of the Arabidopsis TFL1. Mutations in TFL1 and Dt1 both result in the shoot apical meristem (SAM) switching from ve...

  3. CALLUS INDUCTION AND MORPHOGENESIS IN DIOSCOREA ...

    African Journals Online (AJOL)

    Diosgenin is characteristic of the genus Dioscorea (Dioscoreaceae), which is used in partial synthesis of steroid drugs. It was not detected in the crude sapogenin extract of Dioscorea dumetorum and in the calluses. Callus was induced from the meristem of the two genotypes and maintained successfully on Murashige and ...

  4. Proteome Analysis in Arabidopsis Reveals Shoot- and Root-Specific Targets of Cytokinin Action and Differential Regulation of Hormonal Homeostasis

    Czech Academy of Sciences Publication Activity Database

    Žďárská, M.; Zatloukalová, P.; Benítez, M.; Šedo, O.; Potěšil, D.; Novák, Ondřej; Svačinová, Jana; Pešek, Bedřich; Malbeck, Jiří; Vašíčková, J.; Zdráhal, Z.; Hejátko, J.

    2013-01-01

    Roč. 161, č. 2 (2013), s. 918-930 ISSN 0032-0889 Grant - others:GA ČR(CZ) GAP501/11/1150 Program:GA Institutional research plan: CEZ:AV0Z50380511 Keywords : ABSCISIC-ACID * CIS-ZEATIN * MERISTEM ACTIVITY Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 7.394, year: 2013

  5. In planta transformation of sorghum (Sorghum bicolor (L.) Moench)

    Indian Academy of Sciences (India)

    An in planta transformation protocol for sorghum (Sorghum bicolor (L.) Moench) using shoot apical meristem of germinating seedlings is reported in this study. Agrobacterium tumefaciens strain, LBA4404 with pCAMBIA1303 vector and construct pCAMBIA1303TPS1 were individually used for transformation. Since, the ...

  6. The effect of plant growth regulators, cultivars and substrate ...

    African Journals Online (AJOL)

    STORAGESEVER

    2009-10-05

    Oct 5, 2009 ... Therefore, evaluation of commercial varieties in production of virus free potato minitubers is critical. In this study virus free plantlets of 4 potato cultivars of Agria, Marfona, Sante and Burren were achieved with meristem culture ... crop after wheat, rice and maize (Anonymous, 2000). It originates from the ...

  7. Somatic embryogenesis in date palm (Phoenix dactylifera L.) from ...

    African Journals Online (AJOL)

    The shoot apical meristem from young suckers were used as sources of explants for initiation of culture using MS basal medium which contained 2,4-D. This was incubated at 27oC in the dark. Callogenesis was observed as early as the second subculture. Continuous subculture of the callus in the establishment medium at ...

  8. Agrobacterium-mediated transformation of Easter lily (Lilium longiflorum cv. Nellie White)

    Science.gov (United States)

    Conditions were optimized for transient transformation of Lilium longiflorum cv. Nellie White using Agrobacterium tumefaciens. Bulb scale and basal meristem explants were inoculated with A. tumefaciens strain AGL1 containing the binary vector pCAMBIA 2301 which has the uidA gene that codes for ß-gl...

  9. Regulation of plant cells, cell walls and development by mechanical signals

    Energy Technology Data Exchange (ETDEWEB)

    Meyerowitz, Elliot M. [California Inst. of Technology (CalTech), Pasadena, CA (United States)

    2016-06-14

    The overall goal of the revised scope of work for the final year of funding was to characterize cell wall biosynthesis in developing cotyledons and in the shoot apical meristem of Arabidopsis thaliana, as a way of learning about developmental control of cell wall biosynthesis in plants, and interactions between cell wall biosynthesis and the microtubule cytoskeleton. The proposed work had two parts – to look at the effect of mutation in the SPIRAL2 gene on microtubule organization and reorganization, and to thoroughly characterize the glycosyltransferase genes expressed in shoot apical meristems by RNA-seq experiments, by in situ hybridization of the RNAs expressed in the meristem, and by antibody staining of the products of the glycosyltransferases in meristems. Both parts were completed; the spiral2 mutant was found to speed microtubule reorientation after ablation of adjacent cells, supporting our hypothesis that reorganization correlates with microtubule severing, the rate of which is increased by the mutation. The glycosyltransferase characterization was completed and published as Yang et al. (2016). Among the new things learned was that primary cell wall biosynthesis is strongly controlled both by cell type, and by stage of cell cycle, implying not only that different, even adjacent, cells can have different sugar linkages in their (nonshared) walls, but also that a surprisingly large proportion of glycosyltransferases is regulated in the cell cycle, and therefore that the cell cycle regulates wall maturation to a degree previously unrecognized.

  10. 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.

  11. Primary root growth in Arabidopsis thaliana is inhibited by the miR159 mediated repression of MYB33, MYB65 and MYB101.

    Science.gov (United States)

    Xue, Tao; Liu, Zhenhua; Dai, Xuehuan; Xiang, Fengning

    2017-09-01

    Organ growth is a fundamental developmental process basing on cell proliferation and differentiation. The growth of the plant root is sustained by the activity of the root meristem, a process controlled in part by various transcription factors. Here, the miR159 has been identified as a post transcriptional repressor of root growth, on the basis that the mir159ab double mutant developed a larger meristem than did the wild type, and that it formed longer roots. In the mutant, the abundance of MYB33, MYB65 and MYB101 transcript was substantially increased. When MYB33, MYB65 and MYB101 were replaced by the miR159-resistant forms mMYB33, mMYB65 and mMYB101 respectively, the root meristem was similarly enlarged and the growth of the primary root enhanced. MYB65 activity promoted cell division in the root meristem by accelerating the cell cycle. The data suggest that miR159 acts as a key repressor of the primary root's growth, acting through its repression of MYB65 and consequent blocking of the cell cycle. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Phyllotactic pattern and stem cell fate are determined by the Arabidopsis homeobox gene BELLRINGER

    Science.gov (United States)

    Mary E. Byrne; Andrew T. Groover; Joseph R. Fontana; Robert A. Martienssen

    2003-01-01

    Lateral organs in plants arise from the meristem in a stereotypical pattern known as phyllotaxy. Spiral patterns result from initiation of successive organs at a fixed angle of divergence but variable patterns of physical contact. Such patterns ultimately give rise to individual leaves and flowers at positions related to each other by consecutive terms in the...

  13. Isolation and characterization of a floral homeotic gene in Fraxinus nigra causing earlier flowering and homeotic alterations in transgenic Arabidopsis

    Science.gov (United States)

    Jun Hyung Lee; Paula M. Pijut

    2017-01-01

    Reproductive sterility, which can be obtained by manipulating floral organ identity genes, is an important tool for gene containment of genetically engineered trees. In Arabidopsis, AGAMOUS (AG) is the only C-class gene responsible for both floral meristem determinacy and floral organ identity, and its mutations produce...

  14. in vitro production of virus-free sweet potato [ipomoea batatas (l ...

    African Journals Online (AJOL)

    Preferred Customer

    ABSTRACT: Viral disease is the major factor causing significant yield loss in sweet potato. Production of disease-free clones by tissue culture technique increases yield and income of farmers. Meristems from three varieties of sweet potato were cultured at different combinations of BAP, GA3 and NAA in MS basal medium.

  15. Comparative study of the sensitivities of onion and broad bean root ...

    African Journals Online (AJOL)

    ONOS

    2010-07-05

    Jul 5, 2010 ... Chemicals which cause chromosomal aberration (CA) in plant cells frequently produce identical CA in cultured animal cells. Plant species however, differ in sensitivities. Onion and broad bean (BB) root meristem cells were compared for sensitivity to chlorpyrifos (CPF), mercury chloride (HgCl2), ethyl.

  16. Coordination of growth in root and shoot apices by AIL/PLT transcription factors

    NARCIS (Netherlands)

    Scheres, Ben; Krizek, Beth A.

    2018-01-01

    Growth at the root tip and organ generation at the shoot tip depend on the proper functioning of apical meristems and the transitioning of meristematic cell descendants from a proliferating state to cell elongation and differentiation. Members of the AINTEGUMENTA-LIKE/PLETHORA (AIL/PLT)

  17. Arabidopsis ABCG14 protein controls the acropetal translocation of root-synthesized cytokinins

    Czech Academy of Sciences Publication Activity Database

    Zhang, K.; Novák, Ondřej; Wei, Z.; Gou, M.; Zhang, X.; Yu, Y.; Yang, H.; Cai, Y.; Strnad, Miroslav; Liu, Ch.-J.

    2014-01-01

    Roč. 5, FEB 2014 (2014) ISSN 2041-1723 R&D Projects: GA MŠk(CZ) LO1204 Grant - others:GA MŠk(CZ) ED0007/01/01 Program:ED Institutional support: RVO:61389030 Keywords : EQUILIBRATIVE NUCLEOSIDE TRANSPORTER * EXPRESSION ANALYSIS * MERISTEM ACTIVITY Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 11.470, year: 2014

  18. Isolation of a novel MYB transcription factor OsMyb1R from rice and ...

    African Journals Online (AJOL)

    Yomi

    2012-02-23

    Feb 23, 2012 ... Rice Research Institute of Sichuan Agricultural University, Chengdu, Sichuan 611130, China. Accepted 14 February, 2012 ... 1999, 2001; Higginson et al., 2003), regulation of meristem formation, floral and ..... A, Pruss D, Reid J, Tavtigian S, Mitchell J, Eldredge G, Scholl T, Miller. RM, Bhatnagar S, Adey N, ...

  19. Prescribed fire, soil inorganic nitrogen dynamics, and plant responses in a semiarid grassland

    Science.gov (United States)

    David J. Augustine; Paul Brewer; Dana M. Blumenthal; Justin D. Derner; Joseph C. von Fischer

    2014-01-01

    In arid and semiarid ecosystems, fire can potentially affect ecosystem dynamics through changes in soil moisture, temperature, and nitrogen cycling, as well as through direct effects on plant meristem mortality. We examined effects of annual and triennial prescribed fires conducted in early spring on soil moisture, temperature, and N, plant growth, and plant N content...

  20. Modulation of the hormone setting by Rhodococcus fascians results in ectopic KNOX activation in Arabidopsis

    Czech Academy of Sciences Publication Activity Database

    Depuydt, S.; Doležal, Karel; Van Lijsebettens, M.; Moritz, T.; Holsters, M.; Vereecke, D.

    2008-01-01

    Roč. 146, č. 3 (2008), s. 1267-1281 ISSN 0032-0889 Institutional research plan: CEZ:AV0Z50380511 Keywords : KNOTTED1-LIKE HOMEOBOX GENE * CYTOKININ BIOSYNTHESIS * MERISTEM ACTIVITY Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 6.110, year: 2008

  1. A mutually inhibitory interaction between auxin and cytokinin specifies vascular pattern in roots.

    NARCIS (Netherlands)

    Bishopp, A.; Help, H.; El-Showk, S.; Weijers, D.; Scheres, B.J.G.; Friml, J.; Benkova, E.; Pekka Mahonen, A.; Helariutta, Y.

    2011-01-01

    Background Whereas the majority of animals develop toward a predetermined body plan, plants show iterative growth and continually produce new organs and structures from actively dividing meristems. This raises an intriguing question: How are these newly developed organs patterned? In Arabidopsis

  2. Effect of Sunn Hemp (Crotalaria juncea L.) Cutting Date and Planting Density on Weed Suppression in Georgia, USA

    Science.gov (United States)

    A field study was conducted in 2008 and 2009 at the USDA, ARS, Plant Genetic Resources Conservation Unit in Griffin, GA to investigate weed suppression by sunn hemp (Crotalaria juncea L). The objectives were to: 1) evaluate the effects of apical meristem removal (AMR) at three dates [5, 6, and 7 wks...

  3. T.he Mystery Behind Flowering

    Indian Academy of Sciences (India)

    GENERAL. I ARTICLE tion of florigen (flowering hormone) in the leaves, and the florigen is thus translocated to the apical meristem and helps in its conversion into a floral ... 3) Mammalian serum response factor is found to induce the transcription of proto-oncogenes. .... also through his scholarly personality he was a.

  4. The SHORT-ROOT-like gene PtSHR2B is involved in Populus phellogen activity

    Czech Academy of Sciences Publication Activity Database

    Miguel, A.; Milhinhos, A.; Novák, Ondřej; Jones, B.; Miguel, C.M.

    2016-01-01

    Roč. 67, č. 5 (2016), s. 1545-1555 ISSN 0022-0957 R&D Projects: GA MŠk(CZ) LO1204; GA MŠk LK21306 Institutional support: RVO:61389030 Keywords : Cytokinin * lateral meristem * phellogen Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 5.830, year: 2016

  5. Bud banks and their role in vegetative regeneration - a literature review and proposal for simple classification and assessment

    Czech Academy of Sciences Publication Activity Database

    Klimešová, Jitka; Klimeš, Leoš

    2007-01-01

    Roč. 8, - (2007), s. 115-129 ISSN 1433-8319 R&D Projects: GA ČR GA206/01/1039; GA ČR(CZ) GA206/01/1037 Institutional research plan: CEZ:AV0Z60050516 Keywords : bud bank * vegetative regeneration * reserve meristems Subject RIV: EF - Botanics Impact factor: 3.043, year: 2007

  6. Radiobiological researches on Dianthus caryophyllus L. carnation chimeras

    International Nuclear Information System (INIS)

    Pereau-Leroy, Pierre

    1975-01-01

    This research thesis reports a radiobiological study of Dianthus periclinal chimeras performed by submitting plants and plant cuttings at different physiological stages to cobalt-60 gamma irradiation under different dose conditions and rates. The effects of these treatments are studied while growing the so-processed plants and by microscopic examination of sections of irradiated meristems [fr

  7. Effect of different combinations of 6-benzyl amino purine and ...

    African Journals Online (AJOL)

    SNAP CUSTOMER

    2013-02-13

    Feb 13, 2013 ... All sorts of varieties (dessert, cooking, brewing) are grown throughout Ethiopia. These materials are not ... the use of in vitro tissue culture technique. Through meristem micro propagation, pathogen ..... Micro propagation techniques were developed during the past two decades and are now well established ...

  8. Genetic transformation of peanut (Arachis hypogaea L.) using ...

    Indian Academy of Sciences (India)

    Madhu

    tissue culture response and plant regeneration has driven researchers to develop alternate transformation systems that target axillary meristem in the cotyledonary nodes (Somers et al 2003). We report here for the first time the mode of genetic transformation using cotyledonary node (CN) as an explant in peanut mediated ...

  9. The effect of plant growth regulators, cultivars and substrate ...

    African Journals Online (AJOL)

    Nowadays large amounts of potato seed in the world is produced by in vitro virus free minitubers. Therefore, evaluation of commercial varieties in production of virus free potato minitubers is critical. In this study virus free plantlets of 4 potato cultivars of Agria, Marfona, Sante and Burren were achieved with meristem culture ...

  10. Gain-of-function mutants of the cytokinin receptors AHK2 and AHK3 regulate plant organ size, flowering time and plant longevity

    Czech Academy of Sciences Publication Activity Database

    Bartrina, I.; Jensen, H.; Novák, Ondřej; Strnad, Miroslav; Werner, T.; Schmülling, T.

    2017-01-01

    Roč. 173, č. 3 (2017), s. 1783-1797 ISSN 0032-0889 R&D Projects: GA ČR GA15-22322S Institutional support: RVO:61389030 Keywords : SHOOT APICAL MERISTEM * ARABIDOPSIS-THALIANA * HISTIDINE KINASE Subject RIV: CE - Biochemistry OBOR OECD: Plant sciences, botany Impact factor: 6.456, year: 2016

  11. In vitro Production of Virus-Free Sweet Potato [ Ipomoea batatas (L ...

    African Journals Online (AJOL)

    There was 100% sweet potato virus elimination from all the three varieties by meristem culture as observed by using NCM-ELISA technique. Shoot thermotherapy was done for Awassa-83 and Awassa local at 37°C for 31 days and 88.89% and 100% SPFMV and SPCSV virus elimination was achieved for the two varieties, ...

  12. Download this PDF file

    African Journals Online (AJOL)

    Prof. Adipala Ekwamu

    Meristem-tip culture combined with thermotherapy allowed elimination of SPFMV and SPMMV in 77% of plants that were previously infected with the respective viruses. However, elimination of SPCSV was unsuccessful. Key Words: Multiplex RT-PCR, thermotherapy, tissue culture. RÉSUMÉ. En Afrique sub saharienne, ...

  13. SINET: Ethiopian Journal of Science - Vol 34, No 1 (2011)

    African Journals Online (AJOL)

    In vitro Production of Virus-Free Sweet Potato [Ipomoea batatas (L.) Lam] by Meristem Culture and Thermotherapy · EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT. T Feyissa, G Dugassa, 17-28 ...

  14. Root pattern: Shooting in the dark?

    NARCIS (Netherlands)

    Scheres, B.J.G.; Dolan, L.

    1998-01-01

    Root pattern formation takes place in the embryo and is propagated through subsequent growth and development of the seedling root meristem. Pattern is maintained by positional cues and in some cases by local cell interactions. Such interactions are involved in the balance between cell division and

  15. Potential of aeroponics system in the production of quality potato ...

    African Journals Online (AJOL)

    Plants once cleaned through meristem culture and induction of tuberization under aeroponics system, produce high quality potato seed tubers rapidly that are free from contamination of pathogens. Further multiplication of potato seed tubers under aeroponics also compliments tissue culture (micropropagation), as it clones ...

  16. A commercial micropropagation protocol for virupakshi (AAB ...

    African Journals Online (AJOL)

    A commercial micropropagation protocol for virupakshi (AAB) banana via apical meristem. P Karule, V Dalvi, A Kadu, R Chaudhari, VR Subramaniam, AB Patil ... which revealed the existence of genetic uniformity in micro- propagated plants. Keywords: Micropropagation, Virupakshi, hill banana, banana bunchy top virus ...

  17. Treatment of young spruce shoots with SO2 and H2S : Effects on fine root chromosomes in relation to changes in the thiol content and redox state

    NARCIS (Netherlands)

    Wonisch, A; Tausz, M; Muller, M; Weidner, W; De Kok, LJ; Grill, D

    1999-01-01

    Three year old spruce trees (Picea omorika) were exposed to 100 and 225 nl l(-1) SO2 and H2S for three weeks. The number of chromosomal aberrations and the mitotic index in the root tip meristems, and glutathione and cysteine contents in fine roots were determined twice weekly. An increase in

  18. Developmental Anatomy of the Root Cortex of the Basal Monocotyledon, Acorus calamus (Acorales, Acoraceae)

    Science.gov (United States)

    SOUKUP, ALEŠ; SEAGO, JAMES L.; VOTRUBOVÁ, OLGA

    2005-01-01

    • Background and Aims The anatomical structure and development of adventitious roots were analysed in the basal monocotyledon, Acorus calamus, to determine to what extent those features are related to phylogenetic position. • Methods Root specimens were harvested and sectioned, either with a hand microtome or freehand, at varying distances from the root tip and examined under the microscope using a variety of staining techniques. • Key Results Roots of Acorus calamus possess a unique set of developmental characteristics that produce some traits similar to those of another basal angiosperm group, Nymphaeales. The root apical meristem organization seems to be intermediate between that of a closed and an open monocotyledonous root apical meristem organization. The open-type root apical meristem consists of a curved zone of cortical initials and epidermal initials overlying the vascular cylinder initials; the epidermal part of the meristem varies in its association with the cortical initials and columellar initials of the promeristem. The cortex develops an endodermis with only Casparian bands, a dimorphic exodermis with Casparian bands and suberin lamellae, and a polygonal aerenchyma by differential expansion, as also observed in the Nymphaeales and some dicotyledonous species. The stele has characteristics like those of members of the Nymphaeaceae. • Conclusions Specific anatomical and developmental attributes of Acorus roots seem to be related to the phylogenetic position of this genus. PMID:15965268

  19. Histochemical localization and probable functions of calcium oxalate ...

    African Journals Online (AJOL)

    Dr. Julian O. Osuji

    The most remarkable aspect of the histochemistry of this ergastic substance in the edible aroids is the high concentration of the raphide bundles around the root apical meristems. This suggests that the crystals of calcium oxalate serve a protective function in the root of these taxa. Their occurrence in starch granules imply.

  20. PLANT DEVELOPMENT Integration of growth and patterning during vascular tissue formation in Arabidopsis

    Czech Academy of Sciences Publication Activity Database

    De Rybel, B.; Adibi, M.; Breda, A.S.; Wendrich, J.R.; Smit, M.E.; Novák, Ondřej; Yamaguchi, N.; Weijers, D.

    2014-01-01

    Roč. 345, č. 6197 (2014) ISSN 0036-8075 R&D Projects: GA MŠk LK21306; GA MŠk(CZ) LO1204; GA ČR GA14-34792S Institutional support: RVO:61389030 Keywords : DEPENDENT AUXIN GRADIENTS * SOLID-PHASE EXTRACTION * SHOOT APICAL MERISTEM Subject RIV: EF - Botanics Impact factor: 33.611, year: 2014

  1. HDG1 transcription factor targets

    NARCIS (Netherlands)

    Horstman, A.; Boutilier, K.A.; Sanchez Perez, Gabino

    2015-01-01

    The AIL transcription factor BABY BOOM (BBM) is required together with the related PLETHORA proteins for embryo and root meristem development and its expression is sufficient to confer pluripotency and totipotency to somatic tissues. We show that BBM and other AIL proteins interact with multiple

  2. AIL and HDG proteins act antagonistically to control cell proliferation

    NARCIS (Netherlands)

    Horstman, A.; Fukuoka, H.; Muino Acuna, J.M.; Nitsch, L.M.C.; Guo, Changhao; Passarinho, P.A.; Sanchez Perez, G.F.; Immink, R.G.H.; Angenent, G.C.; Boutilier, K.A.

    2015-01-01

    AINTEGUMENTA-LIKE (AIL) transcription factors are key regulators of cell proliferation and meristem identity. Although AIL functions have been well described, the direct signalling components of this pathway are largely unknown.We show that BABY BOOM(BBM) and other AIL proteins physically interact

  3. AINTEGUMENTA-LIKE proteins: hubs in a plethora of networks

    NARCIS (Netherlands)

    Horstman, A.; Willemsen, V.; Boutilier, K.A.; Heidstra, R.

    2014-01-01

    Members of the AINTEGUMENTA-LIKE (AIL) family of APETALA 2/ETHYLENE RESPONSE FACTOR (AP2/ERF) domain transcription factors are expressed in all dividing tissues in the plant, where they have central roles in developmental processes such as embryogenesis, stem cell niche specification, meristem

  4. African Journal of Biotechnology - Vol 13, No 38 (2014)

    African Journals Online (AJOL)

    Abnormal mitosis in root meristem cells of Allium cepa L. induced by a fabric dye reactive turquoise blue (Procion MX) · EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT. SK Tripathy, S Patel ...

  5. A Simplified Experimental Scheme for the Study of Mitosis.

    Science.gov (United States)

    Gill, John

    1980-01-01

    A procedure is described for providing preparations of dividing cells from root apical meristems, requiring only inexpensive equipment and minimal experimental skill, and using 8-Hydroxyquinoline and Toluidene-blue as a chromosome stain. The method has been sucessfully tested in schools and yields permanent preparations of adequate quality for…

  6. Rice zinc finger protein DST enhances grain production through controlling Gn1a/OsCKX2 expression.

    Science.gov (United States)

    Li, Shuyu; Zhao, Bingran; Yuan, Dingyang; Duan, Meijuan; Qian, Qian; Tang, Li; Wang, Bao; Liu, Xiaoqiang; Zhang, Jie; Wang, Jun; Sun, Jiaqiang; Liu, Zhao; Feng, Yu-Qi; Yuan, Longping; Li, Chuanyou

    2013-02-19

    The phytohormone cytokinin (CK) positively regulates the activity and function of the shoot apical meristem (SAM), which is a major parameter determining seed production. The rice (Oryza sativa L.) Gn1a/OsCKX2 (Grain number 1a/Cytokinin oxidase 2) gene, which encodes a cytokinin oxidase, has been identified as a major quantitative trait locus contributing to grain number improvement in rice breeding practice. However, the molecular mechanism of how the expression of OsCKX2 is regulated in planta remains elusive. Here, we report that the zinc finger transcription factor DROUGHT AND SALT TOLERANCE (DST) directly regulates OsCKX2 expression in the reproductive meristem. DST-directed expression of OsCKX2 regulates CK accumulation in the SAM and, therefore, controls the number of the reproductive organs. We identify that DST(reg1), a semidominant allele of the DST gene, perturbs DST-directed regulation of OsCKX2 expression and elevates CK levels in the reproductive SAM, leading to increased meristem activity, enhanced panicle branching, and a consequent increase of grain number. Importantly, the DST(reg1) allele provides an approach to pyramid the Gn1a-dependent and Gn1a-independent effects on grain production. Our study reveals that, as a unique regulator of reproductive meristem activity, DST may be explored to facilitate the genetic enhancement of grain production in rice and other small grain cereals.

  7. Genotoxic effects of industrial wastewater on Allium cepa L.

    African Journals Online (AJOL)

    STORAGESEVER

    2009-05-04

    May 4, 2009 ... The aim of this research is to study the effects of different concentrations of water on both incoming and outgoing in central biological and chemical wastewater treatment plant in Manisa (Turkey) organized industrial zone (MOIZ) on the Allium cepa L. root meristems, having been rooted in distilled water for ...

  8. Dissection of genetic regulation of compound inflorescence development inMedicago truncatula.

    Science.gov (United States)

    Cheng, Xiaofei; Li, Guifen; Tang, Yuhong; Wen, Jiangqi

    2018-02-08

    Development of inflorescence architecture is controlled by genetic regulatory networks. TERMINAL FLOWER1 ( TFL1 ), APETALA1 ( AP1 ), LEAFY ( LFY ) and FRUITFULL ( FUL ) are core regulators for inflorescence development. To understand the regulation of compound inflorescence development, we characterized mutants of corresponding orthologous genes, MtTFL1 , MtAP1 , SINGLE LEAFLET1 ( SGL1 ) and MtFULc , in Medicago truncatula , and analyzed expression patterns of these genes. Results indicate that MtTFL1 , MtFULc , MtAP1 and SGL1 play specific roles in identity determination of primary inflorescence meristems, secondary inflorescence meristems, floral meristems and common primordia, respectively. Double mutation of MtTFL1 and MtFULc transforms compound inflorescences to simple flowers, whereas single mutation of MtTFL1 changes the inflorescence branching pattern from monopodial to sympodial. Double mutant mtap1sgl1 completely loses floral meristem identity. We conclude that inflorescence architecture in M. truncatula is controlled by spatiotemporal expression of MtTFL1 , MtFULc , MtAP1 and SGL1 through reciprocal repression. Although this regulatory network shares similarity with the pea model, it has specificity in regulating inflorescence architecture in M truncatula This study establishes M. truncatula as an excellent genetic model for understanding compound inflorescence development in related legume crops. © 2018. Published by The Company of Biologists Ltd.

  9. Retinoblastoma-like RRB gene of arabidopsis thaliana

    Science.gov (United States)

    Durfee, Tim; Feiler, Heidi; Gruissem, Wilhelm; Jenkins, Susan; Roe, Judith; Zambryski, Patricia

    2004-02-24

    This invention provides methods and compositions for altering the growth, organization, and differentiation of plant tissues. The invention is based on the discovery that, in plants, genetically altering the levels of Retinoblastoma-related gene (RRB) activity produces dramatic effects on the growth, proliferation, organization, and differentiation of plant meristem.

  10. Effects of different media concentartions on callogensis in sugar ...

    African Journals Online (AJOL)

    SAM

    2014-03-12

    Mar 12, 2014 ... technique were made on sugarcane by Naz (2003). Standardization of protocols for in vitro multiplication of sugarcane through callus culture, axillary bud and shoot tip culture have been reported by many authors (Devi and. Srinivasan, 2006). However, reports are few on young meristem callus culture in ...

  11. Rozwój Narcissus poeticus L. [Development of Narcissus poeticus L.

    Directory of Open Access Journals (Sweden)

    B. Jamiołowska

    2015-06-01

    Full Text Available One generation of Narcissus poeticus develops during three seasons. The vegetative stage of the meristem lasts 11 months. It changes to a floral apex in the second year and initiates all the flower elements from the first days of June to mid August. The plants bloom in the third year.

  12. Tsaeda embaba

    African Journals Online (AJOL)

    SERVER

    2008-02-19

    Feb 19, 2008 ... The culture tubes were covered with plastic caps and kept in a growth chamber for 3 to 4 weeks at. 20/18oC day/night ... to 4 weeks using single node cuttings to build up the stock plants necessary for the experiment. .... meristems to attain a size large enough for microcutting and transferring to regular CMS ...

  13. Effect of thidiazuron on in vivo shoot proliferation of popular banana ...

    African Journals Online (AJOL)

    Moistened sawdust was steam-sterilized for 45 minutes and then filled for cooling in wooden propagators. Banana suckers were cleaned to remove roots and surface-sterilized for 15 seconds. The sterilized corms were deshealthed to expose axillary buds and decorticated to suppress the apical meristems. These corns ...

  14. Transcription Factors Expressed in Lateral Organ Boundaries: Identification of Downstream Targets

    Energy Technology Data Exchange (ETDEWEB)

    Springer, Patricia S

    2010-07-12

    The processes of lateral organ initiation and patterning are central to the generation of mature plant form. Characterization of the molecular mechanisms underlying these processes is essential to our understanding of plant development. Communication between the shoot apical meristem and initiating organ primordia is important both for functioning of the meristem and for proper organ patterning, and very little is known about this process. In particular, the boundary between meristem and leaf is emerging as a critical region that is important for SAM maintenance and regulation of organogenesis. The goal of this project was to characterize three boundary-expressed genes that encode predicted transcription factors. Specifically, we have studied LATERAL ORGAN BOUNDARIES (LOB), LATERAL ORGAN FUSION1 (LOF1), and LATERAL ORGAN FUSION2 (LOF2). LOB encodes the founding member of the LOB-DOMAIN (LBD) plant-specific DNA binding transcription factor family and LOF1 and LOF2 encode paralogous MYB-domain transcription factors. We characterized the genetic relationship between these three genes and other boundary and meristem genes. We also used an ectopic inducible expression system to identify direct targets of LOB.

  15. The Effect of 2, 4-Dichlorophenoxy Acetic Acid (2, 4-D ...

    African Journals Online (AJOL)

    Experiment was designed and conducted to determine the most appropriate concentration of 2, 4-Dichlorophenoxy Acetic Acid suitable for callus induction in sugarcane. Explants were obtained from apical meristems of two sugarcane cultivars (SP726180 and CO-001) and cultured in a modified MS medium supplemented ...

  16. Cytogenice Studies on Bambara groundnut ( Vigna subterranea (L ...

    African Journals Online (AJOL)

    The study reports the result of analysis of chromosomes of Vigna subterranea performed in the mitotic prometaphase and metaphase stages using conventional techniques. The somatic chromosome study was done using the shoot meristem as the root tips persistently showed very low mitotic indices. The result revealed ...

  17. Variation of Growth and Disease Characters Between Clones of Potato (Solanum tuberosum L.)

    DEFF Research Database (Denmark)

    Nielsen, Steen Lykke; Bång, H; Kotkas, K

    2007-01-01

    The occurrence and magnitude of variation of selected characters in clones derived from meristem tips of four potato cultivars in field trials in three countries was assessed. Recorded were: the number of plants per plot; maturity of plants; skin and flesh colour; tuber deformity; time of emergence...

  18. Role of LLD, a new locus for leaflet/pinna morphogenesis in Pisum ...

    Indian Academy of Sciences (India)

    Unknown

    that of leaves in later stages of plant life respectively. (Laux and Jurgans 1997) and serve as the progenitor of lateral organs. A SAM has a population of stem cells distributed in its central (CZ), peripheral (PZ) and rib. (RZ) zones. The descendants of PZ cells generate the primordial meristems for the leaf and flower organs ...

  19. Apical bud toughness tests and tree sway movements to examine crown abrasion: preliminary results

    Science.gov (United States)

    Tyler Brannon; Wayne Clatterbuck

    2012-01-01

    Apical bud toughness differences were examined for several species to determine if crown abrasion affects shoot growth of determinate and indeterminate species during stand development. Determinate buds will set and harden after initial shoot elongation in the spring, while the indeterminate shoots form leaves from the apical meristem continuously based on the...

  20. Comparative study of the sensitivities of onion and broad bean root ...

    African Journals Online (AJOL)

    Chemicals which cause chromosomal aberration (CA) in plant cells frequently produce identical CA in cultured animal cells. Plant species however, differ in sensitivities. Onion and broad bean (BB) root meristem cells were compared for sensitivity to chlorpyrifos (CPF), mercury chloride (HgCl2), ethyl methanesulphonate ...

  1. Karyological investigations on Erigeron canadensis L. and E. annuus (L. Pers. from natural stands in Poland

    Directory of Open Access Journals (Sweden)

    K. Bijok

    2015-01-01

    Full Text Available The number of chromosomes in metaphases root meristems of Erigeron canadensis L. (2n= 18 and E. annuus (L. Pers. (2n=27 was determined. The chromosomes of both species showed a morphological differentiation - they were heterobrachial or isobrachial; E. annuus had an additional unpaired isobrachial chromosome.

  2. Effects of gamma-irradiation and granozan on the proliferative activity of plant tissue and its modification by peroxidase

    Energy Technology Data Exchange (ETDEWEB)

    Agabeili, R.A.; Melikova, N.K. (AN Azerbajdzhanskoj SSR, Baku. Biologicheskij Tsentr)

    1984-01-01

    Mitotic activity of meristem cells of seedlings of welsh onion Allium fistulesum L. under the effect of gamma-rays, granosane fungicide is studied as well as its modification by peroxidase. Antimitotic granosane activity is established, as well as peroxidase ability to stimulate proliferative ability of cells in the case of its inhibition by gamma-rays and granosane.

  3. Differences in proleptic and epicormic shoot structures in relation to water deficit and growth rate in almond trees (Prunus dulcis).

    Science.gov (United States)

    Negrón, Claudia; Contador, Loreto; Lampinen, Bruce D; Metcalf, Samuel G; Guédon, Yann; Costes, Evelyne; DeJong, Theodore M

    2014-02-01

    Shoot characteristics differ depending on the meristem tissue that they originate from and environmental conditions during their development. This study focused on the effects of plant water status on axillary meristem fate and flowering patterns along proleptic and epicormic shoots, as well as on shoot growth rates on 'Nonpareil' almond trees (Prunus dulcis). The aims were (1) to characterize the structural differences between proleptic and epicormic shoots, (2) to determine whether water deficits modify shoot structures differently depending on shoot type, and (3) to determine whether shoot structures are related to shoot growth rates. A hidden semi-Markov model of the axillary meristem fate and number of flower buds per node was built for two shoot types growing on trees exposed to three plant water status treatments. The models segmented observed shoots into successive homogeneous zones, which were compared between treatments. Shoot growth rates were calculated from shoot extension measurements made during the growing season. Proleptic shoots had seven successive homogeneous zones while epicormic shoots had five zones. Shoot structures were associated with changes in growth rate over the season. Water deficit (1) affected the occurrence and lengths of the first zones of proleptic shoots, but only the occurrence of the third zone was reduced in epicormic shoots; (2) had a minor effect on zone flowering patterns and did not modify shoot or zone composition of axillary meristem fates; and (3) reduced growth rates, although patterns over the season were similar among treatments. Two meristem types, with different latency durations, produced shoots with different growth rates and distinct structures. Differences between shoot type structure responses to water deficit appeared to reflect their ontogenetic characteristics and/or resource availability for their development. Tree water deficit appeared to stimulate a more rapid progression through ontogenetic states.

  4. OsRAMOSA2 Shapes Panicle Architecture through Regulating Pedicel Length

    Directory of Open Access Journals (Sweden)

    Huan Lu

    2017-09-01

    Full Text Available The panicle architecture of rice is an important characteristic that influences reproductive success and yield. It is largely determined by the number and length of the primary and secondary branches. The number of panicle branches is defined by the inflorescence meristem state between determinacy and indeterminacy; for example, the maize ramosa2 (ra2 mutant has more branches in its tassel through loss of spikelet determinacy. Some genes and factors influencing the number of primary and secondary branches have been studied, but little is known about the molecular mechanism underlying pedicel development, which also influences panicle architecture. We report here that rice OsRAMOSA2 (OsRA2 gene modifies panicle architecture through regulating pedicel length. Ectopic expression of OsRA2 resulted in a shortened pedicel while inhibition of OsRA2 through RNA interference produced elongated pedicel. In addition, OsRA2 influenced seed morphology. The OsRA2 protein localized to the nucleus and showed transcriptional activation in yeast; in accordance with its function in pedicel development, OsRA2 mRNA was enriched in the anlagen of axillary meristems, such as primary and secondary branch meristems and the spikelet meristems of young panicles. This indicates a conserved role of OsRA2 for shaping the initial steps of inflorescence architecture. Genetic analysis revealed that OsRA2 may control panicle architecture using the same pathway as that of the axillary meristem gene LAX1 (LAX PANICLE1. Moreover, OsRA2 acted downstream of RCN2 in regulating pedicel and branch lengths, but upstream of RCN2 for control of the number of secondary branches, indicating that branch number and length development in the panicle were respectively regulated using parallel pathway. Functional conservation between OsRA2 and AtLOB, and the conservation and diversification of RA2 in maize and rice are also discussed.

  5. Fall nitrogen enhances spring nitrogen enhanced flowering in the long day strawberry cultivar ‘Elan’

    Directory of Open Access Journals (Sweden)

    Edward F. Durner

    2017-04-01

    Full Text Available Architectural analysis describes the position and fate (vegetative or floral of plant meristems to account for differences in their sensitivity to stimuli depending on developmental stage and position on the plant. To provide further insight into the flowering responses of long day strawberries to nitrogen, ‘Elan’ seedlings were fertilized in mid-October, overwintered in a greenhouse, then dissected the following March and their floral architecture evaluated. Additional plants from fall N treatments were placed under ND and fertilized weekly for four weeks with 100, 400, 800 or 1200 ppm N during greenhouse-forcing under ND and growth monitored until June. Plants were dissected after forcing and their floral architecture evaluated. Fall fertilized plants were significantly more floral than non-fertilized controls before forcing. Some axillary buds of fertilized plants formed floral branch crowns but there were no floral branch crowns on non-fertilized plants. Precocity was not affected by fall N and 400, 800 or 1200 ppm spring N were equally effective in accelerating flowering (+1 week compared to 100 ppm spring N. Fall N enhanced the number of inflorescences and flowers produced by the primary crown. Spring N enhanced flowering of branch crowns and the total numbers of inflorescences and flowers per plant. Inflorescence production was a qualitative response to N while flower production was quantitative. Architectural models of post-forcing dissected plants provided additional insight. All 100 ppm spring N terminal meristems were floral while 400 and 800 ppm spring N meristems were less floral. All terminal meristems of plants receiving 100 ppm fall N before 1200 ppm spring N were floral but meristems from plants that did not receive fall N before 1200 ppm spring N were much less floral. Branch crown formation was enhanced with elevated (400, 800 or 1200 ppm spring N and prior fall N enhanced their floral nature.

  6. The origin of the sporophyte shoot in land plants: a bryological perspective

    Science.gov (United States)

    Ligrone, Roberto; Duckett, Jeffrey G.; Renzaglia, Karen S.

    2012-01-01

    Background Land plants (embryophytes) are monophyletic and encompass four major clades: liverworts, mosses, hornworts and polysporangiophytes. The liverworts are resolved as the earliest divergent lineage and the mosses as sister to a crown clade formed by the hornworts and polysporangiophytes (lycophytes, monilophytes and seed plants). Alternative topologies resolving the hornworts as sister to mosses plus polysporangiophytes are less well supported. Sporophyte development in liverworts depends only on embryonic formative cell divisions. A transient basal meristem contributes part of the sporophyte in mosses. The sporophyte body in hornworts and polysporangiophytes develops predominantly by post-embryonic meristematic activity. Scope This paper explores the origin of the sporophyte shoot in terms of changes in embryo organization. Pressure towards amplification of the sporangium-associated photosynthetic apparatus was a major driver of sporophyte evolution. Starting from a putative ancestral condition in which a transient basal meristem produced a sporangium-supporting seta, we postulate that in the hornwort–polysporangiophyte lineage the basal meristem acquired indeterminate meristematic activity and ectopically expressed the sporangium morphogenetic programme. The resulting sporophyte body plan remained substantially unaltered in hornworts, whereas in polysporangiophytes the persistent meristem shifted from a mid-embryo to a superficial position and was converted into an ancestral shoot apical meristem with the evolution of sequential vegetative and reproductive growth. Conclusions The sporophyte shoot is interpreted as a sterilized sporangial axis interpolated between the embryo and the fertile sporangium. With reference to the putatively ancestral condition found in mosses, the sporophyte body plans in hornworts and polysporangiophytes are viewed as the product of opposite heterochronic events, i.e. an anticipation and a delay, respectively, in the

  7. Inhibition of cell proliferation, cell expansion and differentiation by the Arabidopsis SUPERMAN gene in transgenic tobacco plants.

    Science.gov (United States)

    Bereterbide, A; Hernould, M; Castera, S; Mouras, A

    2001-11-01

    Plant development depends upon the control of growth, organization and differentiation of cells derived from shoot and root meristems. Among the genes involved in flower organ determination, the cadastral gene SUPERMAN controls the boundary between whorls 3 and 4 and the growth of the adaxial outer ovule integument by down-regulating cell divisions. To determine the precise function of this gene we overexpressed ectopically the Arabidopsis thaliana (L.) Heynh. SUPERMAN gene in tobacco (Nicotiana tabacum L.). The transgenic plants exhibited a dwarf phenotype. Histologically and cytologically detailed analyses showed that dwarfism is correlated with a reduction in cell number, which is in agreement with the SUPERMAN function in Arabidopsis. Furthermore, a reduction in cell expansion and an impairment of cell differentiation were observed in tobacco organs. These traits were observed in differentiated vegetative and floral organs but not in meristem structures. A potential effect of the SUPERMAN transcription factor in the control of gibberellin biosynthesis is discussed.

  8. PHB3 Maintains Root Stem Cell Niche Identity through ROS-Responsive AP2/ERF Transcription Factors in Arabidopsis

    Directory of Open Access Journals (Sweden)

    Xiangpei Kong

    2018-01-01

    Full Text Available The root stem cell niche, which is composed of four mitotically inactive quiescent center (QC cells and the surrounding actively divided stem cells in Arabidopsis, is critical for growth and root development. Here, we demonstrate that the Arabidopsis prohibitin protein PHB3 is required for the maintenance of root stem cell niche identity by both inhibiting proliferative processes in the QC and stimulating cell division in the proximal meristem (PM. PHB3 coordinates cell division and differentiation in the root apical meristem by restricting the spatial expression of ethylene response factor (ERF transcription factors 115, 114, and 109. ERF115, ERF114, and ERF109 mediate ROS signaling, in a PLT-independent manner, to control root stem cell niche maintenance and root growth through phytosulfokine (PSK peptide hormones in Arabidopsis.

  9. EMF1, a novel protein involved in the control of shoot architecture and flowering in Arabidopsis

    DEFF Research Database (Denmark)

    Aubert, D.; Chen, L.; Moon, Y.-H.

    2001-01-01

    shares common motifs that include nuclear localization signals, P-loop, and LXXLL elements. Alteration of EMF1 expression in transgenic plants caused progressive changes in flowering time, shoot determinacy, and inflorescence architecture. EMF1 and its related sequence may belong to a new class......Shoot architecture and flowering time in angiosperms depend on the balanced expression of a large number of flowering time and flower meristem identity genes. Loss-of-function mutations in the Arabidopsis EMBRYONIC FLOWER (EMF) genes cause Arabidopsis to eliminate rosette shoot growth and transform...... the apical meristem from indeterminate to determinate growth by producing a single terminal flower on all nodes. We have identified the EMF1 gene by positional cloning. The deduced polypeptide has no homology with any protein of known function except a putative protein in the rice genome with which EMF1...

  10. Diploidization of cucumber (Cucumis sativus L. haploids by colchicine treatment

    Directory of Open Access Journals (Sweden)

    Vesselina Nikolova

    2014-01-01

    Full Text Available Haploid cucumber plants are totally infertile and do not undergo spontaneous diploidization. The use of haploids depends on the possibility of doubling the chromosome number and the obtaining of stable doubled haploids (DH. Four haploids of different genotypes propagated vegetatively were treated with colchicine in order to obtain DH. The following procedures were used: 1 apical shoot meristem treatment, 2 soaking of shoot explants, 3 placing of shoot explants on medium with colchicine. Plants of the C1 generation were evaluated in respect to morphological and cytological characters and fertility. The best result of 20.9% DH was obtained after repeated treatment of the meristem with colchicine. A large group of chimeras (28.5% was also distinguished as were haploids and tetraploids. DH plants were fertile and gave uniform progeny. Chimeras had a decreased fertility and showed disturbances in meiotic divisions.

  11. Demarcation of mutant-carrying regions in barley plants after ethylmethane-sulfonate seed treatment

    DEFF Research Database (Denmark)

    Jacobsen, P.

    1966-01-01

    The branching pattern of the barley plant is analyzed and the anatomical structure of the resting barley embryo studied in longitudinal and cross-sections as well as by dissection techniques. The frequency and distribution of ethylmethane-sulfonate induced chloroplast and morphological seedling...... was obtained.The absence of cluster sharing allows the recognition in the barley plant of 8 mutually exclusive mutant sectors which never had a mutant cluster in common. The anatomical analysis proves that the barley embryo contains at least 6 separate shoot meristems or prospective shoot meristems, which...... in the embryo of the seed. These will, however, not appear in plants under normal development.There are, according to the present analysis, 6 spikes for which 1 or 2 functional initial cells for their sporogenous tissue are already established in the embryo, i.e. at the time of mutagenic treatment. Except...

  12. Estimation of paddy water temperature during crop development

    International Nuclear Information System (INIS)

    Centeno, H.G.S.; Horie, T.

    1996-01-01

    The crop meristem is in direct contact with paddy water during crop's vegetative stage. Ambient air temperature becomes an important factor in crop development only when internodes elongate sufficiently for the meristem to rise above the water surface. This does not occur until after panicle initiation. Crop growth at vegetative stage is affected more by water temperature than the most commonly measured air temperature. During transplanting in 1992 dry season, the maximum paddy water temperature was 10 deg C higher than the maximum air temperature. For rice crop models, the development of a submodel to estimate water temperature is important to account the effect of paddy water temperature on plant growth. Paddy water temperature is estimated from mean air temperature, solar radiation, and crop canopy. The parameters of the model were derived using the simplex method on data from the 1993 wet- and dry-season field experiments at IRRI

  13. Primary root protophloem differentiation requires balanced phosphatidylinositol-4,5-biphosphate levels and systemically affects root branching.

    OpenAIRE

    Rodriguez-Villalon Antia; Gujas Bojan; van Wijk Ringo; Munnik Teun; Hardtke Christian S

    2015-01-01

    Protophloem is a specialized vascular tissue in growing plant organs, such as root meristems. In Arabidopsis mutants with impaired primary root protophloem differentiation, brevis radix (brx) and octopus (ops), meristematic activity and consequently overall root growth are strongly reduced. Second site mutation in the protophloem-specific presumed phosphoinositide 5-phosphatase cotyledon vascular pattern 2 (CVP2), but not in its homolog CVP2-like 1 (CVL1), partially rescues brx defects. Consi...

  14. MAIL1 is essential for development of the primary root but not of anchor roots

    OpenAIRE

    Ühlken, Christine; Hoth, Stefan; Weingartner, Magdalena

    2014-01-01

    MAIN-LIKE1 (MAIL1) is a ubiquitously expressed nuclear protein, which has a crucial function during root development. We have recently described loss of function mutants for MAIL1, in which the organization and function of the primary root meristem is lost soon after germination. Moreover cell differentiation is impaired resulting in primary root growth arrest soon after emergence. Here we show that mail1 mutants form several anchor roots from the hypocotyl to root junction. These anchor root...

  15. Development of carpels and ovules in Dialypetalanthus fuscescens Kuhlm. (Rubiaceae): an enigmatic taxon

    OpenAIRE

    Figueiredo, Rogério da Costa; Vieira, Ricardo Cardoso; Mariath, Jorge Ernesto de Araújo; Moço, Maria Cecilia de Chiara; Toni, Karen L. G. De

    2017-01-01

    ABSTRACT Dialypetalanthus is a monospecific genus that occurs in the Amazon Basin of Brazil, Bolivia and Peru and occupies a controversial position among the Rubiaceae. We continue this taxonomic discussion with the overall aim of clarifying the systematic position of D. fuscescens within the Rubiaceae. To accomplish this, we analyzed the ontogeny of its gynoecium, in particular the floral meristem, as well as the development of the carpels and cauline placentation. Gynosporogenesis and the d...

  16. Flowering pathway is regulated by bulb size in Lilium longiflorum (Easter lily).

    Science.gov (United States)

    Lazare, S; Zaccai, M

    2016-07-01

    Lilium longiflorum (Easter lily) vegetative propagation occurs through production of underground bulbs containing apical and axillary meristems. In addition, sexual reproduction is achieved by flowering of elongated shoots above the bulb. It is generally accepted that L. longiflorum has an obligatory requirement for vernalisation and that long day (LD) regime hastens flowering. However, the effect of bulb size and origin, with respect to axillary or apical meristems on flowering, as well as the interactions between these meristems are largely unknown. The aim of this study was to explore the effect of bulb size, vernalisation and photoperiod on L. longiflorum flowering. To this end, we applied vernalisation and photoperiod treatments to the different bulb sizes and used a system of constant ambient temperature of 25 °C, above vernalisation spectrum, to avoid cold-dependent floral induction during plant growth. Vernalisation and LD hasten flowering in all bulbs. Large, non-vernalised bulbs invariably remained at a vegetative stage. However, small non-vernalised bulbs flowered under LD conditions. These results demonstrate for the first time that cold exposure is not an obligatory prerequisite for L. longiflorum flowering, and that an alternative flowering pathway can bypass vernalisation in small bulbs. We suggest that apical dominance interactions determine the distinct flowering pathways of the apical and axillary meristems. Similar floral induction is achieved in propagated bulblets from scaling. These innovative findings in the field of geophyte floral induction represent valuable applicative knowledge for lily production. © 2016 German Botanical Society and The Royal Botanical Society of the Netherlands.

  17. Remote effetc of chronic irradiation of plants within the zone of Eastern-Ural radioactive track

    International Nuclear Information System (INIS)

    Pozolotina, V.N.; Molchanova, I.V.; Karavaeva, E.N.; Sergeev, A.M.; Kulikov, N.V.

    1992-01-01

    In studying the living soil cover on the territory of the Sverdlov region within the zone of the Eastern-Ural radioactive track, it has been found that 33 years after the accident at the Southern Urals a population of Taraxacum officinale Wigg. has been developed on soils conatninated with 90 Sr which displayes a high level of cytogenetic damages to meristem cells and high growth rate, and which is resistant to repeated radiation effects

  18. Over-expressing Salicornia europaea (SeNHX1) gene in tobacco ...

    African Journals Online (AJOL)

    An increase of salt tolerance in transgenics was observed both in vitro and in pot culture. When exposed to either 138 mM or 172 mM NaCl in vitro, the transgenic apical meristem and stem segments with buds exhibited stronger salt-tolerance than their wild-type counterparts. In pot soil with 10.2 mg g-1 DW Na+ stress, ...

  19. Spatio-temporal relief from hypoxia and production of reactive oxygen species during bud burst in grapevine (Vitis vinifera).

    Science.gov (United States)

    Meitha, Karlia; Konnerup, Dennis; Colmer, Timothy D; Considine, John A; Foyer, Christine H; Considine, Michael J

    2015-09-01

    Plants regulate cellular oxygen partial pressures (pO2), together with reduction/oxidation (redox) state in order to manage rapid developmental transitions such as bud burst after a period of quiescence. However, our understanding of pO2 regulation in complex meristematic organs such as buds is incomplete and, in particular, lacks spatial resolution. The gradients in pO2 from the outer scales to the primary meristem complex were measured in grapevine (Vitis vinifera) buds, together with respiratory CO2 production rates and the accumulation of superoxide and hydrogen peroxide, from ecodormancy through the first 72 h preceding bud burst, triggered by the transition from low to ambient temperatures. Steep internal pO2 gradients were measured in dormant buds with values as low as 2·5 kPa found in the core of the bud prior to bud burst. Respiratory CO2 production rates increased soon after the transition from low to ambient temperatures and the bud tissues gradually became oxygenated in a patterned process. Within 3 h of the transition to ambient temperatures, superoxide accumulation was observed in the cambial meristem, co-localizing with lignified cellulose associated with pro-vascular tissues. Thereafter, superoxide accumulated in other areas subtending the apical meristem complex, in the absence of significant hydrogen peroxide accumulation, except in the cambial meristem. By 72 h, the internal pO2 gradient showed a biphasic profile, where the minimum pO2 was external to the core of the bud complex. Spatial and temporal control of the tissue oxygen environment occurs within quiescent buds, and the transition from quiescence to bud burst is accompanied by a regulated relaxation of the hypoxic state and accumulation of reactive oxygen species within the developing cambium and vascular tissues of the heterotrophic grapevine buds. © The Author 2015. Published by Oxford University Press on behalf of the Annals of Botany Company.

  20. INDUÇÃO E IDENTIFICACAO DE POLIPLOIDIA EM Hymenaea courbaril L. var. stilbocarpa (Hayne Lee et Lang.

    Directory of Open Access Journals (Sweden)

    Diego Antonio Ottonelli Bona

    2016-01-01

    Full Text Available The Hymenaea courbaril var. stilbocarpa wood has a high density being employed in construction, carpentry and laminate. The stem exudes a rich terpene resin which can be used in the varnish industry. The endocarp of the fruit is edible and can be eaten raw. The chromosomal duplication of forest species aims to maximize economic interest features, such as those related to the development and forest gain. This study aimed to induce and verify polyploidy in root meristem cells of Hymenaea courbaril through morphological and cytological features. To induce polyploidy, the root meristems were exposed to the trifluralin herbicide at a concentration of 3 μM at 4 ºC for 14 (control, 24, 48, 72 and 96 h. Then, the rootlets were stored for 24 h in a closed flask and refrigerated in methanol: acetic acid solution (high purity in the ratio 3:1, at -4 ºC. Root meristems were digested in pectinase enzyme (SigmaTM. Mitotic cells were obtained by cell dissociation, air drying and hotplate. 30 cells in metaphase were colored with Giemsa 5% and analyzed. The stomata were obtained from young plantlets of each treatment under the same physical and chemical conditions. For stomata analysis, was used epidermal print of adaxial leaf, with universal instant adhesive (Super BonderTM. 200 stomata were analyzed of each treatment. Among the four treatments evaluated, the exposure of root meristem for 96 h in 3 μM trifluralin, at 4 ºC, induced genome duplication in Hymenaea courbaril L. var. stilbocarpa with 2n = 4x = 48 chromosomes and stomata average size of 0.215 mm, being superior to the other treatments.

  1. Induction of callogenesis in Ipomoea obscura (L.) Ker- Gawl, a little ...

    African Journals Online (AJOL)

    Maximum number of root meristems and microroots were formed in 1.25 mg/L NAA with the combination of 0.5 mg/L BAP (1:4 v/v). Leaf, nodal and internodal segments as explants were cultured on MS media containing 2,4 D at 0.5, 1.25, 2.50, 5.0 and 10.0 mg/L, for callus induction. Only leaf tips initiated callogenesis with ...

  2. Effects of polyamines and polyamine biosynthetic inhibitors on mitotic activity of Allium cepa root tips.

    Science.gov (United States)

    Unal, Meral; Palavan-Unsal, Narcin; Tufekci, M A

    2008-03-01

    The genotoxic and cytotoxic effects of exogenous polyamines (PAs), putrescine (Put), spermidine (Spd), spermine (Spm) and PA biosynthetic inhibitors, alpha-difluoromethylornithine (DFMO), cyclohexilamine (CHA), methylglioxal bis-(guanylhydrazone) (MGBG) were investigated in the root meristems of Allium cepa L. The reduction of mitotic index and the induction of chromosomal aberrations such as bridges, stickiness, c-mitotic anaphases, micronuclei, endoredupliction by PAs and PA biosynthetic inhibitors were observed and these were used as evidence of genotoxicity and cytotoxicity.

  3. The shady side of leaf development

    DEFF Research Database (Denmark)

    Merelo, Paz; Botterweg Paredes, Esther; Heisler, Marcus G.

    2017-01-01

    Leaves are present in all land plants and are specialized organs for light harvesting. They arise at the flanks of the shoot apical meristem (SAM), and develop into lamina structures that exhibit adaxial/abaxial (upper/lower side of the leaf) polarity. At the molecular level, an intricate regulat...... differentiation. The REV/KAN1 module directly and antagonistically regulates the expression of several genes involved in shade-induced growth and auxin biosynthetic enzymes....

  4. Effect of 2 MHz ultrasound irradiation on Pisum sativum roots

    International Nuclear Information System (INIS)

    Miller, M.W.; Voorhees, S.M.; Carstensen, E.L.; Kaufman, G.E.

    1976-01-01

    The effect of 2 MHz ultrasound at intensity levels from 2.5 to 22 W/cm 2 on the growth rate and mitotic index of Pisum sativum roots was studied. The ultrasound produced an immediate reduction in the growth rate on the first postexposure day, followed by a gradual recovery to the control value. Ultrasound reduced the root meristem mitotic index. Intensity- and time-dependent relations were found for the growth rate and mitotic index reductions

  5. Efficacy of Tissue Culture in Virus Elimination from Caprifig and Female Fig Varieties (Ficus carica L.

    Directory of Open Access Journals (Sweden)

    Chokri Bayoudh

    2017-06-01

    Full Text Available Fig mosaic disease (FMD is a viral disease that spreads in all Tunisian fig (Ficus carica L. orchards. RT-PCR technique was applied to leaf samples of 29 fig accessions of 15 fig varieties from the fig germplasm collection of High Agronomic Institute (I.S.A of Chatt-Mariem, to detect viruses associated to FMD. Analysis results show that 65.5% of the accessions (19/29 and 80.0% (12/15 of the fig varieties are infected by FMD-associated viruses. From all fig accessions, 41.4% of them are with single infection (one virus and 24.1% are with multi-infections (2 virus and more. Viruses infecting fig leaf samples are Fig mosaic virus (FMV (20.7%, Fig milde-mottle-associated virus (FMMaV (17.25%, Fig fleck associated virus (FFkaV (3.45%, and Fig cryptic virus (FCV (55.17%. A reliable protocol for FCV and FMMaV elimination from 4 local fig varieties Zidi (ZDI, Soltani (SNI, Bither Abiadh (BA, and Assafri (ASF via in vitro culture of 3 meristem sizes was established and optimized. With this protocol, global sanitation rates of 79.46%, 65.55%, 68.75%, and 70.83% respectively for ZDI, SNI, BA, and ASF are achieved. For all sanitized varieties, the effectiveness of meristem culture for the elimination of FCV and FMMaV viruses was related to meristem size. Meristem size 0.5 mm provides the highest sanitation rates ranging from 70% to 90%.

  6. Efficacy of Tissue Culture in Virus Elimination from Caprifig and Female Fig Varieties (Ficus caricaL.).

    Science.gov (United States)

    Bayoudh, Chokri; Elair, Manel; Labidi, Rahma; Majdoub, Afifa; Mahfoudhi, Naima; Mars, Messaoud

    2017-06-01

    Fig mosaic disease (FMD) is a viral disease that spreads in all Tunisian fig ( Ficus carica L.) orchards. RT-PCR technique was applied to leaf samples of 29 fig accessions of 15 fig varieties from the fig germplasm collection of High Agronomic Institute (I.S.A) of Chatt-Mariem, to detect viruses associated to FMD. Analysis results show that 65.5% of the accessions (19/29) and 80.0% (12/15) of the fig varieties are infected by FMD-associated viruses. From all fig accessions, 41.4% of them are with single infection (one virus) and 24.1% are with multi-infections (2 virus and more). Viruses infecting fig leaf samples are Fig mosaic virus (FMV) (20.7%), Fig milde-mottle-associated virus (FMMaV) (17.25%), Fig fleck associated virus (FFkaV) (3.45%), and Fig cryptic virus (FCV) (55.17%). A reliable protocol for FCV and FMMaV elimination from 4 local fig varieties Zidi (ZDI), Soltani (SNI), Bither Abiadh (BA), and Assafri (ASF) via in vitro culture of 3 meristem sizes was established and optimized. With this protocol, global sanitation rates of 79.46%, 65.55%, 68.75%, and 70.83% respectively for ZDI, SNI, BA, and ASF are achieved. For all sanitized varieties, the effectiveness of meristem culture for the elimination of FCV and FMMaV viruses was related to meristem size. Meristem size 0.5 mm provides the highest sanitation rates ranging from 70% to 90%.

  7. Intronic sequences are required for AINTEGUMENTA-LIKE6 expression in Arabidopsis flowers

    OpenAIRE

    Krizek, Beth A.

    2015-01-01

    Background The AINTEGUMENTA-LIKE6/PLETHORA3 (AIL6/PLT3) gene of Arabidopsis thaliana is a key regulator of growth and patterning in both shoots and roots. AIL6 encodes an AINTEGUMENTA-LIKE/PLETHORA (AIL/PLT) transcription factor that is expressed in the root stem cell niche, the peripheral region of the shoot apical meristem and young lateral organ primordia. In flowers, AIL6 acts redundantly with AINTEGUMENTA (ANT) to regulate floral organ positioning, growth, identity and patterning. Experi...

  8. Cytokinins Are Initial Targets of Light in the Control of Bud Outgrowth(1[OPEN])

    Czech Academy of Sciences Publication Activity Database

    Roman, H.; Girault, T.; Barbier, F.; Peron, T.; Brouard, N.; Pěnčík, Aleš; Novák, Ondřej; Vian, A.; Sakr, S.; Lothier, J.; Le Gourrierec, J.; Leduc, N.

    2016-01-01

    Roč. 172, č. 1 (2016), s. 489-509 ISSN 0032-0889 R&D Projects: GA MŠk(CZ) LO1204; GA MŠk LK21306 Institutional support: RVO:61389030 Keywords : cell-cycle regulation * pea axillary buds * oryza-sativa l. * apical dominance * rosa sp * arabidopsis-thaliana * lateral buds * meristem activity * plant-responses * acts downstream Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 6.456, year: 2016

  9. Cell-Type-Specific Cytokinin Distribution within the Arabidopsis Primary Root Apex

    Czech Academy of Sciences Publication Activity Database

    Antoniadi, I.; Plačková, Lenka; Simonovik, B.; Doležal, Karel; Turnbull, C.; Ljung, K.; Novák, Ondřej

    2015-01-01

    Roč. 27, č. 7 (2015), s. 1955-1967 ISSN 1040-4651 R&D Projects: GA ČR GA14-34792S; GA MŠk(CZ) LO1204; GA MŠk LK21306 Institutional support: RVO:61389030 Keywords : SOLID-PHASE EXTRACTION * ENDOPLASMIC-RETICULUM * MERISTEM ACTIVITY Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 8.538, year: 2015

  10. [Genetic regulation of plant shoot stem cells].

    Science.gov (United States)

    Al'bert, E V; Ezhova, T A

    2013-02-01

    This article describes the main features of plant stem cells and summarizes the results of studies of the genetic control of stem cell maintenance in the apical meristem of the shoot. It is demonstrated that the WUS-CLV gene system plays a key role in the maintenance of shoot apical stem cells and the formation of adventitious buds and somatic embryos. Unconventional concepts of plant stem cells are considered.

  11. Description des embryons de Phaseolus vulgaris en cours d'avortement issus de plantes mutagénisées au méthanesulfonate d'éthyle (EMS)

    OpenAIRE

    Silué, Souleymane; Diarrasouba, Nafan; Fofana, Inza Jesus; Muhovski, Yordan; Toussaint, André; Mergeai, Guy; Jacquemin, Jean-Marie; Baudoin, Jean-Pierre

    2013-01-01

    The aim of this study was to describe the embryos abortion process and the inheritance of the embryos abortion trait in Phaseolus vulgaris plants deficient in seed development. These plants were isolated within the second generation of an ethyl methanesulfonate (EMS) TILLING population of P. vulgaris cv. 'BAT93'. Mutant embryos show abnormalities mainly in suspensors, shoot apical meristem (SAM) and cotylédons from the globular to the cotyledon stages and abort before maturity compared to tho...

  12. Sample preparation method for induced mutation on orchid

    International Nuclear Information System (INIS)

    Suhaimi Musa; Sakinah Ariffin

    2005-01-01

    Studies on the induction of mutation in Dendrobium orchid at MINT has produced a number of new orchid mutant cultivars. Tissue culture techniques on orchid seeds and meristem cloning are employed in preparing the samples for the mutation induction. Solid medium based on the Murashige and Skoog (1962) and liquid medium based on Vacin and Went (1949) were found to be suitable in producing protocorm like bodies (PLBs) that are required for the irradiation treatment. (Author)

  13. Development of cycad ovules and seeds. 2. Histological and ultrastructural aspects of ontogeny of the embryo in Encephalartos natalensis (Zamiaceae).

    Science.gov (United States)

    Woodenberg, Wynston Ray; Berjak, Patricia; Pammenter, N W; Farrant, Jill M

    2014-07-01

    Development of the embryo of Encephalartos natalensis from a rudimentary meristematic structure approximately 700 μm in length extends over 6 months after the seed is shed from the strobilus. Throughout its development, the embryo remains attached to a long suspensor. Differentiation of the shoot meristem flanked by two cotyledonary protuberances occurs over the first 2 months, during which peripheral tannin channels become apparent. Tannins, apparently elaborated by the endoplasmic reticulum, first accumulate in the large central vacuole and ultimately fill the channel. By the fourth month of development, the root meristem is apparent and procambial tissue forming discrete vascular bundles can be discerned in the elongating cotyledons. Between 4 and 6 months, mucilage ducts differentiate; after 6 months, when the seed becomes germinable, the embryo is characterised by cotyledons far longer than the axis. Shoot and root meristem cells remain ultrastructurally similar throughout embryo ontogeny, containing small vacuoles, many well-differentiated mitochondria and endoplasmic reticulum (ER) profiles, abundant polysomes, plastids containing small starch deposits and Golgi bodies. Unusually, however, Golgi bodies are infrequent in other cells including those elaborating mucilage which is accumulated in distended ER and apparently secreted into the duct lumen directly by ER-derived vesicles. The non-meristematic cells accumulate massive starch deposits to the exclusion of any protein bodies and only very sparse lipid, features which are considered in terms of the prolonged period of embryo development and the high atmospheric oxygen content of the Carboniferous Period, when cycads are suggested to have originated.

  14. [Meristematic characteristics of tumors initiated by Agrobacterium tumefaciens in pea plants].

    Science.gov (United States)

    Vinogradova, A P; Lebedeva, M A; Lutova, L A

    2015-01-01

    It is known that two key groups of plant hormones--auxins and cytokinins--play an important role in plant tumor development. The formation of Agrobacterium-induced tumors results from the horizontal transfer of bacterial oncogenes involved in the biosynthesis of these hormones in the plant genome. The role of transcriptional factors in plant tumor development is poorly investigated. It can be assumed that tumor development associated with abnormal cell proliferation can be controlled by the same set of transcription factors that control normal cell proliferation and, in particular, transcription factors that regulate meristem activity. In the present study, we analyzed the histological organization and distribution of proliferating cells in tumors induced by Agrobacterium tumefaciens on pea hypocotyls. In addition, the expression of a set of meristem-specific genes with Agrobacterium tumefaciens-induced tumor development was analyzed. In general, our results indicate that meristematic structures are present in A. tumefaciens-induced tumors and that the development of such tumors is associated with increased expression of a key gene regulating the root apical meristem--the WOX5 gene.

  15. Pectin-induced changes in cell wall mechanics underlie organ initiation in Arabidopsis.

    Science.gov (United States)

    Peaucelle, Alexis; Braybrook, Siobhan A; Le Guillou, Laurent; Bron, Emeric; Kuhlemeier, Cris; Höfte, Herman

    2011-10-25

    Tissue mechanics have been shown to play a key role in the regulation of morphogenesis in animals [1-4] and may have an equally important role in plants [5-9]. The aerial organs of plants are formed at the shoot apical meristem following a specific phyllotactic pattern [10]. The initiation of an organ from the meristem requires a highly localized irreversible surface deformation, which depends on the demethylesterification of cell wall pectins [11]. Here, we used atomic force microscopy (AFM) to investigate whether these chemical changes lead to changes in tissue mechanics. By mapping the viscoelasticity and elasticity in living meristems, we observed increases in tissue elasticity, correlated with pectin demethylesterification, in primordia and at the site of incipient organs. Measurements of tissue elasticity at various depths showed that, at the site of incipient primordia, the first increases occurred in subepidermal tissues. The results support the following causal sequence of events: (1) demethylesterification of pectin is triggered in subepidermal tissue layers, (2) this contributes to an increase in elasticity of these layers-the first observable mechanical event in organ initiation, and (3) the process propagates to the epidermis during the outgrowth of the organ. Copyright © 2011 Elsevier Ltd. All rights reserved.

  16. Antiproliferative and genotoxic effects of nature identical and artificial synthetic food additives of aroma and flavor

    Directory of Open Access Journals (Sweden)

    R. D. M. Nunes

    Full Text Available Abstract This study aimed to analyze the antiproliferative and genotoxic potential of synthetic food flavorings, nature identical passion fruit and artificial vanilla. This assessment used root meristem cells of Allium cepa L., in exposure times of 24 and 48 hours and using doses of 0.2; 0.4 and 0.6 mL. Roots were fixed in Carnoy’s solution, hydrolyzed in hydrochloric acid, stained with acetic orcein and analyzed with optical microscope at 400× magnification, 5,000 cells for each treatment. For data analysis, it was used Chi-square test at 5%. Doses of 0.2 mL at ET 48 h; 0.4 and 0.6 mL at ET 24 and 48 h of passion fruit flavor, and the three doses of the vanilla flavor at ET 24 and 48 h significantly reduced the cell division rate in the meristems of roots, proving to be cytotoxic. Doses of 0.2; 0.4 and 0.6 mL of the passion fruit additive, and the three doses of vanilla tested, in the two exposure times, induced mitotic spindle changes and micronuclei formation in the cells of the test organism used, proving to be genotoxic. Therefore, under the studied conditions, flavoring solutions of vanilla and passion fruit, marketed nationally and internationally, significantly altered the functioning of the cell cycle in root meristem cells of A. cepa.

  17. Genomic Approach to Study Floral Development Genes in Rosa sp.

    Science.gov (United States)

    Chauvet, Aurélie; Maene, Marion; Pécrix, Yann; Yang, Shu-Hua; Jeauffre, Julien; Thouroude, Tatiana; Boltz, Véronique; Martin-Magniette, Marie-Laure; Janczarski, Stéphane; Legeai, Fabrice; Renou, Jean-Pierre; Vergne, Philippe; Le Bris, Manuel; Foucher, Fabrice; Bendahmane, Mohammed

    2011-01-01

    Cultivated for centuries, the varieties of rose have been selected based on a number of flower traits. Understanding the genetic and molecular basis that contributes to these traits will impact on future improvements for this economically important ornamental plant. In this study, we used scanning electron microscopy and sections of meristems and flowers to establish a precise morphological calendar from early rose flower development stages to senescing flowers. Global gene expression was investigated from floral meristem initiation up to flower senescence in three rose genotypes exhibiting contrasted floral traits including continuous versus once flowering and simple versus double flower architecture, using a newly developed Affymetrix microarray (Rosa1_Affyarray) tool containing sequences representing 4765 unigenes expressed during flower development. Data analyses permitted the identification of genes associated with floral transition, floral organs initiation up to flower senescence. Quantitative real time PCR analyses validated the mRNA accumulation changes observed in microarray hybridizations for a selection of 24 genes expressed at either high or low levels. Our data describe the early flower development stages in Rosa sp, the production of a rose microarray and demonstrate its usefulness and reliability to study gene expression during extensive development phases, from the vegetative meristem to the senescent flower. PMID:22194838

  18. Effects of PEG-Induced Water Deficit in Solanum nigrum on Zn and Ni Uptake and Translocation in Split Root Systems

    Directory of Open Access Journals (Sweden)

    Urs Feller

    2015-06-01

    Full Text Available Drought strongly influences root activities in crop plants and weeds. This paper is focused on the performance of the heavy metal accumulator Solanum nigrum, a plant which might be helpful for phytoremediation. The water potential in a split root system was decreased by the addition of polyethylene glycol (PEG 6000. Rubidium, strontium and radionuclides of heavy metals were used as markers to investigate the uptake into roots, the release to the shoot via the xylem, and finally the basipetal transport via the phloem to unlabeled roots. The uptake into the roots (total contents in the plant was for most makers more severely decreased than the transport to the shoot or the export from the shoot to the unlabeled roots via the phloem. Regardless of the water potential in the labeling solution, 63Ni and 65Zn were selectively redistributed within the plant. From autoradiographs, it became evident that 65Zn accumulated in root tips, in the apical shoot meristem and in axillary buds, while 63Ni accumulated in young expanded leaves and roots but not in the meristems. Since both radionuclides are mobile in the phloem and are, therefore, well redistributed within the plant, the unequal transfer to shoot and root apical meristems is most likely caused by differences in the cell-to-cell transport in differentiation zones without functional phloem (immature sieve tubes.

  19. Use of Tissue Culture Techniques for Producing Virus-Free Plant in Garlic and Their Identification through Real-Time PCR

    Directory of Open Access Journals (Sweden)

    Hatıra Taşkın

    2013-01-01

    Full Text Available This study was performed for comparison of meristem culture technique with shoot tip culture technique for obtaining virus-free plant, comparison of micropropagation success of two different nutrient media, and determination of effectiveness of real-time PCR assay for the detection of viruses. Two different garlic species (Allium sativum and Allium tuncelianum and two different nutrient media were used in this experiment. Results showed that Medium 2 was more successful compared to Medium 1 for both A. tuncelianum and A. sativum (Kastamonu garlic clone. In vitro plants obtained via meristem and shoot tip cultures were tested for determination of onion yellow dwarf virus (OYDV and leek yellow stripe virus (LYSV through real-time PCR assay. In garlic plants propagated via meristem culture, we could not detect any virus. OYDV and LYSV viruses were detected in plants obtained via shoot tip culture. OYDV virus was observed in amount of 80% and 73% of tested plants for A. tuncelianum and A. sativum, respectively. LYSV virus was found in amount of 67% of tested plants of A. tuncelianum and in amount of 87% of tested plants of A. sativum in this study.

  20. Cytotoxic, genotoxic and mutagenic potential of UHT whole milk

    Directory of Open Access Journals (Sweden)

    Brenda de Lima CARVALHO

    Full Text Available Abstract This study evaluated the action at the cellular level of long life whole milk, full type of six renowned companies operating in the Brazilian market, as well as in other South American countries. The evaluation was performed using root meristem cells of Allium cepa L., at exposure times 24 and 48 hours, directly in milk products marketed. The results indicated that all the milk samples reduced root meristem cell proliferation, proving, in this study, a significant cytotoxic effect. Still, exposure to milk resulted in a significant frequency of mitotic spindle changes in meristem cells, characterizing these foods as genotoxic and mutagenic under the study conditions. It can be concluded that the long life milk samples caused significant genetic instability to cells of the examined tissue. The results obtained for cytotoxic, mutagenic and genotoxic action of these long life milks are of great relevance because, to date, there are no published toxicity studies on such foods and food additives present in the composition.

  1. Final Scientific/Technical report for "ABI8: Prototype of a novel signaling factor"

    Energy Technology Data Exchange (ETDEWEB)

    Finkelstein, Ruth R. [Univ. of California, Santa Barbara, CA (United States)

    2013-02-21

    The Arabidopsis thaliana ABSCISIC ACID-INSENSITIVE8 locus encodes a highly conserved plant-specific protein that mediates abscisic acid (ABA) and sugar responses essential for growth. Although initial database comparisons revealed no domains of predictable function, it has recently been re-annotated as a member of the Glycosyltransferase family A. However, this function has not been demonstrated experimentally and no specific substrates have been identified. Mutations affecting ABI8 are near-lethal due to pleiotropic yet specific effects including altered ABA signaling, sugar transport, cell wall synthesis, root meristem maintenance, vascular patterning, and male sterility. Because the predicted sequence initially provided no clues, we used a guilt by association strategy to address function of this protein by determining its subcellular localization and identifying interacting proteins. Our studies showed that ABI8 is localized to the endomembrane system and may interact with proteins implicated in Golgi trafficking, lignification, and stress signaling. We found that the root meristem arrest reflects decreased auxin accumulation and resulting decreases in regulators required for meristem identity, all of which can be rescued by added glucose. Further studies showed that this glucose-dependence reflects reduced glucose uptake as well as the decreased expression of sugar-mobilizing enzymes. This work suggests that ABI8 may regulate trafficking of membrane proteins such as auxin transporters and cellulose synthase, but this hypothesis has not yet been tested. The altered gene expression is likely to be a secondary or later effect of this pleiotropic mutation.

  2. The milkweed pod1 Gene Encodes a KANADI Protein That Is Required for Abaxial/Adaxial Patterning in Maize Leaves[W

    Science.gov (United States)

    Candela, Héctor; Johnston, Robyn; Gerhold, Abigail; Foster, Toshi; Hake, Sarah

    2008-01-01

    Leaf primordia initiate from the shoot apical meristem with inherent polarity; the adaxial side faces the meristem, while the abaxial side faces away from the meristem. Adaxial/abaxial polarity is thought to be necessary for laminar growth of leaves, as mutants lacking either adaxial or abaxial cell types often develop radially symmetric lateral organs. The milkweed pod1 (mwp1) mutant of maize (Zea mays) has adaxialized sectors in the sheath, the proximal part of the leaf. Ectopic leaf flaps develop where adaxial and abaxial cell types juxtapose. Ectopic expression of the HD-ZIPIII gene rolled leaf1 (rld1) correlates with the adaxialized regions. Cloning of mwp1 showed that it encodes a KANADI transcription factor. Double mutants of mwp1-R with a microRNA-resistant allele of rld1, Rld1-N1990, show a synergistic phenotype with polarity defects in sheath and blade and a failure to differentiate vascular and photosynthetic cell types in the adaxialized sectors. The sectored phenotype and timing of the defect suggest that mwp1 is required late in leaf development to maintain abaxial cell fate. The phenotype of mwp1; Rld1 double mutants shows that both genes are also required early in leaf development to delineate leaf margins as well as to initiate vascular and photosynthetic tissues. PMID:18757553

  3. The milkweed pod1 gene encodes a KANADI protein that is required for abaxial/adaxial patterning in maize leaves.

    Science.gov (United States)

    Candela, Héctor; Johnston, Robyn; Gerhold, Abigail; Foster, Toshi; Hake, Sarah

    2008-08-01

    Leaf primordia initiate from the shoot apical meristem with inherent polarity; the adaxial side faces the meristem, while the abaxial side faces away from the meristem. Adaxial/abaxial polarity is thought to be necessary for laminar growth of leaves, as mutants lacking either adaxial or abaxial cell types often develop radially symmetric lateral organs. The milkweed pod1 (mwp1) mutant of maize (Zea mays) has adaxialized sectors in the sheath, the proximal part of the leaf. Ectopic leaf flaps develop where adaxial and abaxial cell types juxtapose. Ectopic expression of the HD-ZIPIII gene rolled leaf1 (rld1) correlates with the adaxialized regions. Cloning of mwp1 showed that it encodes a KANADI transcription factor. Double mutants of mwp1-R with a microRNA-resistant allele of rld1, Rld1-N1990, show a synergistic phenotype with polarity defects in sheath and blade and a failure to differentiate vascular and photosynthetic cell types in the adaxialized sectors. The sectored phenotype and timing of the defect suggest that mwp1 is required late in leaf development to maintain abaxial cell fate. The phenotype of mwp1; Rld1 double mutants shows that both genes are also required early in leaf development to delineate leaf margins as well as to initiate vascular and photosynthetic tissues.

  4. A genetic framework for flowering-time pathways in Citrus spp.

    Directory of Open Access Journals (Sweden)

    Marcelo Carnier Dornelas

    2007-01-01

    Full Text Available Floral transition is one the most drastic changes occurring during the life cycle of a plant. The shoot apical meristem switches from the production of leaves with associated secondary shoot meristems to the production of flower meristems. This transition is abrupt and generally irreversible, suggesting it is regulated by a robust gene regulatory network capable of driving sharp transitions. The moment at which this transition occurs is precisely determined by environmental and endogenous signals. A large number of genes acting within these pathways have been cloned in model herbaceous plants such as Arabidopsis thaliana. In this paper, we report the results of our search in the Citrus expressed sequence tag (CitEST database for expressed sequence tags (ESTs showing sequence homology with known elements of flowering-time pathways. We have searched all sequence clusters in the CitEST database and identified more than one hundred Citrus spp sequences that codify putative conserved elements of the autonomous, vernalization, photoperiod response and gibberelic acid-controlled flowering-time pathways. Additionally, we have characterized in silico putative members of the Citrus spp homologs to the Arabidopsis CONSTANS family of transcription factors.

  5. Mixoploidy and cytotypes: a study of possible vegetative species differentiation in stapeliads (Asclepiadaceae

    Directory of Open Access Journals (Sweden)

    F. Albers

    1991-09-01

    Full Text Available Mixoploidy is common in proembryos and embryos as well as in meristems of radicles, primary, secondary and adventitious roots and in innovation shoots of stapeliad species (Asclepiadaceae. The proportion of polyploid cells in the meristem of single adventitious roots is significantly higher than in meristems of primary and secondary roots. This may lead to a complete polyploidisation of adventitious roots. Innovation shoots display a low percentage of polyploid cells, comparable to the condition found in primary and secondary roots. Nevertheless cells of different euploid levels are frequently found. During field studies, however, individuals of a given population were always found to have the same chromosome number: infraspecific polyploidy was found in only three out of 305 investigated stapeliad species. Genera with an orthotropic growth form were found to be diploid throughout, whereas the genera of which the members spread vegetatively by means of innovation shoots, comprise di-, tetra- and polyploid species. This phenomenon can be ascribed to ecological rather than morphological factors. The often proposed hypothesis that new cytotypes can have a vegetative origin is not found to be acceptable.

  6. Adaptation to the local environment by modifications of the photoperiod response in crops.

    Science.gov (United States)

    Nakamichi, Norihito

    2015-04-01

    Flowering plants produce a meristem at the shoot tip where specialized tissue generates shoot apical meristems at the appropriate time to differentiate into reproductive structures, pollinate and efficiently generate seeds. The complex set of molecular and phenological events culminating in development of a flowering meristem is referred to as 'flowering time'. Flowering time affects plant productivity because plants dedicate energy to produce flowers and seeds rather than vegetative tissue once the molecular decision to initiate flowering has been taken. Thus, initiation of flowering time is an important decision in plants, especially in annual plants including crops. Humans have introduced crops into latitudes and climate areas far from their origin or natural ecosystem, requiring in many cases modification of native flowering times. Recent molecular-genetic studies shed light on the genetic basis related to such introductions. In this review, recent progress regarding crop introductions and their genetic bases are summarized, as well as the potential of other agricultural plants to be introduced into different climatic zones. © The Author 2014. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists.

  7. Cortical development in roots of the aquatic plant Pontederia cordata (Pontederiaceae).

    Science.gov (United States)

    Seago, J L; Peterson, C A; Enstone, D E

    2000-08-01

    Adventitious roots of marsh-grown Pontederia cordata were examined to determine cortical development and structure. The innermost layer of the ground meristem forms the endodermis and aerenchymatous cortex. The outermost layer of the early ground meristem undergoes a precise pattern of oblique and periclinal cell divisions to produce a single or double layer of prohypodermis with an anchor cell for each radial file of aerenchyma cells. At maturity, endodermal cell walls are modified only by narrow Casparian bands. The central regions of the ground meristem become proaerenchyma and exhibit asymmetric cell division and expansion. They produce an aerenchymatous zone with barrel-shaped large cells and irregularly shaped small cells traversing the aerenchyma horizontally along radii; some crystalliferous cells with raphides are present in the aerenchyma. The walls of the hypodermis are modified early by polyphenols. The outermost layer of the hypodermis later matures into an exodermis with Casparian bands that are impermeable to berberine, an apoplastic tracer dye. The nonexodermal layer(s) of the hypodermis has suberin-modified walls. Radial files of aerenchyma are usually connected by narrow protuberances near their midpoints, the aerenchyma lacunae having been produced by expansion of cells along walls lining intercellular spaces. We are terming this type of aerenchyma development, which is neither schizogenous nor lysigenous, "differential expansion."

  8. AIL and HDG proteins act antagonistically to control cell proliferation.

    Science.gov (United States)

    Horstman, Anneke; Fukuoka, Hiroyuki; Muino, Jose M; Nitsch, Lisette; Guo, Changhua; Passarinho, Paul; Sanchez-Perez, Gabino; Immink, Richard; Angenent, Gerco; Boutilier, Kim

    2015-02-01

    Aintegumenta-like (AIL) transcription factors are key regulators of cell proliferation and meristem identity. Although AIL functions have been well described, the direct signalling components of this pathway are largely unknown. We show that baby boom (BBM) and other AIL proteins physically interact with multiple members of the L1-expressed homeodomain glabrous (HDG) transcription factor family, including HDG1, HDG11 and HDG12. Overexpression of HDG1, HDG11 and HDG12 restricts growth due to root and shoot meristem arrest, which is associated with reduced expression of genes involved in meristem development and cell proliferation pathways, whereas downregulation of multiple HDG genes promotes cell overproliferation. These results suggest a role for HDG proteins in promoting cell differentiation. We also reveal a transcriptional network in which BBM and HDG1 regulate several common target genes, and where BBM/AIL and HDG regulate the expression of each other. Taken together, these results suggest opposite roles for AIL and HDG proteins, with AILs promoting cell proliferation and HDGs stimulating cell differentiation, and that these functions are mediated at both the protein-protein interaction and transcriptional level. © 2015. Published by The Company of Biologists Ltd.

  9. Comparative anatomy and morphology of Vitis vinifera (Vitaceae) somatic embryos from solid- and liquid-culture-derived proembryogenic masses.

    Science.gov (United States)

    Jayasankar, S; Bondada, Bhaskar R; Li, Zhijian; Gray, D J

    2003-07-01

    Ontogeny of somatic embryos of grapevine (Vitis vinifera) produced from solid- and liquid-culture-derived proembryogenic masses (PEM) was compared using light and scanning electron microscopy. Somatic embryos produced from solid-medium-derived PEM (SPEM) had large cotyledons, little or no visible suspensor structure, and a relatively undeveloped concave shoot apical meristem, whereas those from liquid-medium-derived PEM (LPEM) had smaller cotyledons, a distinct suspensor, and a flat-to-convex shoot apical meristem. The convex shoot apical meristem in LPEM-derived somatic embryos formed as early as the heart stage of development; it was 4-6 cell layers deep and rich in protein. Suspensors persisted in fully developed and mature LPEM-derived somatic embryos. The SPEM-derived somatic embryos exhibited dormancy, as do mature zygotic embryos, which also have a rudimentary suspensor, whereas LPEM-derived embryos were not dormant. We hypothesize that the presence of a persistent suspensor in LPEM-derived somatic embryos modulates development, ultimately resulting in rapid germination and a high plant-regeneration rate.

  10. Use of tissue culture techniques for producing virus-free plant in garlic and their identification through real-time PCR.

    Science.gov (United States)

    Taşkın, Hatıra; Baktemur, Gökhan; Kurul, Mehmet; Büyükalaca, Saadet

    2013-01-01

    This study was performed for comparison of meristem culture technique with shoot tip culture technique for obtaining virus-free plant, comparison of micropropagation success of two different nutrient media, and determination of effectiveness of real-time PCR assay for the detection of viruses. Two different garlic species (Allium sativum and Allium tuncelianum) and two different nutrient media were used in this experiment. Results showed that Medium 2 was more successful compared to Medium 1 for both A. tuncelianum and A. sativum (Kastamonu garlic clone). In vitro plants obtained via meristem and shoot tip cultures were tested for determination of onion yellow dwarf virus (OYDV) and leek yellow stripe virus (LYSV) through real-time PCR assay. In garlic plants propagated via meristem culture, we could not detect any virus. OYDV and LYSV viruses were detected in plants obtained via shoot tip culture. OYDV virus was observed in amount of 80% and 73% of tested plants for A. tuncelianum and A. sativum, respectively. LYSV virus was found in amount of 67% of tested plants of A. tuncelianum and in amount of 87% of tested plants of A. sativum in this study.

  11. EARLY BUD-BREAK 1 (EBB1) is a regulator of release from seasonal dormancy in poplar trees

    Science.gov (United States)

    Yordanov, Yordan S.; Ma, Cathleen; Strauss, Steven H.; Busov, Victor B.

    2014-01-01

    Trees from temperate latitudes transition between growth and dormancy to survive dehydration and freezing stress during winter months. We used activation tagging to isolate a dominant mutation affecting release from dormancy and identified the corresponding gene EARLY BUD-BREAK 1 (EBB1). We demonstrate through positioning of the tag, expression analysis, and retransformation experiments that EBB1 encodes a putative APETALA2/Ethylene responsive factor transcription factor. Transgenic up-regulation of the gene caused early bud-flush, whereas down-regulation delayed bud-break. Native EBB1 expression was highest in actively growing apices, undetectable during the dormancy period, but rapidly increased before bud-break. The EBB1 transcript was localized in the L1/L2 layers of the shoot meristem and leaf primordia. EBB1-overexpressing transgenic plants displayed enlarged shoot meristems, open and poorly differentiated buds, and a higher rate of cell division in the apex. Transcriptome analyses of the EBB1 transgenics identified 971 differentially expressed genes whose expression correlated with the EBB1 expression changes in the transgenic plants. Promoter analysis among the differentially expressed genes for the presence of a canonical EBB1-binding site identified 65 putative target genes, indicative of a broad regulatory context of EBB1 function. Our results suggest that EBB1 has a major and integrative role in reactivation of meristem activity after winter dormancy. PMID:24951507

  12. Radiobiological research on carnation chimerae Dianthus Caryophyllus L

    International Nuclear Information System (INIS)

    Pereau-Leroy, Pierre.

    1975-01-01

    A radiobiological study of periclinal carnation chimerae is carried out by subjecting whole plants and cuttings at different physiological stages to cobalt 60 gamma radiation under different dose and dose rate conditions. The effects of these treatments are observed during cultivation of the treated plants and by microscopic examination of irradiated meristem sections. The destruction of meristem cells in proportions varying with the irradiation conditions leads to structural changes in the chimerae; the more frequent change is the formation of genetically homogeneous stalks from different genotypes existing in the irradiated plant. Treatment by ionizing radiations is thus a practical means of detecting periclinical chimerae which, as in the case of carnations, are very common in plants grown by vegetative propagation. However since more than two independent meristem cell groups are usually present it is not possible by this method alone to define the distribution of the differentent genotypes in these groups; additional genetic studies or cell labelling such as chlorophyll or genoma mutations are then necessary [fr

  13. Processed fruit juice ready to drink: screening acute toxicity at the cellular level

    Directory of Open Access Journals (Sweden)

    Erick Leal da Silva

    2017-06-01

    Full Text Available The present study evaluated the acute toxicity at the cellular level of processed juice ready for consumption Orange and Grape flavors, produced by five companies with significant influence on the food market of South American countries, especially in Brazil. This evaluation was performed in root meristem cells of Allium cepa L., at the exposure times of 24 and 48 hours, directly with marketed liquid preparations. Based on the results, it was found that fruit juices, of all companies considered, promoted significant antiproliferative effect to root meristems at the exposure time of 24 hours and resulted in at both exposure times, statistically significant number of mitotic spindle changes and chromosomal breaks. Therefore, under the study conditions, all juice samples analyzed were cytotoxic, genotoxic and mutagenic to root meristem cells. These results indicate that such beverages have relevant potential to cause cellular disorders and, thus, need to be evaluated more fully in more complex test systems, as those in rodents, and then establish specific toxicity at the cellular level of these juices and ensure the well-being of those who consume them.

  14. DNA damage in Cicer plant grown on soil polluted with heavy metals

    Directory of Open Access Journals (Sweden)

    Sazada Siddiqui

    2015-07-01

    Full Text Available In recent years industrialization is growing rapidly due to which the pollution load in water, air and soil is increasing day by day. Heavy metal pollution of the soil has raised concern in recent years due to its possible impact not only on human health but also on the plant system. To understand the consequences on plant systems, in the present study we cultivated the Cicer plant in soil polluted with heavy metals (Cd, Pb, Cr and Zn collected from the Jhansi City of Uttar Pradesh, India with a geographical area of 502.75 thousand hectares. Seeds of Cicer were germinated in polluted soil sites such as T1 (Garden Soil, Control; T2 (Bharat Heavy Electrical Limited (BHEL-Industrial; T3 (BHEL-Agricultural; T4 (Bijouli-Industrial; T5 (Bijouli-Agricultural. The effect of soil polluted with the heavy metals was analyzed by studying the percentage of seed germination, radicle length (RL, mitotic index (MI and chromosomal aberrations (CAs in root tip meristems. The results revealed that polluted soil with heavy metals T2 (BHEL-Industrial site and T4 (Bijouli-Industrial site had a significant impeding effect on the root meristem activity in Cicer as noticed by the reduction in seed germination percentage and RL compared to the control. Additionally, the variation in the percentage of mitotic abnormalities was observed. In general, increased percentage of chromosomal aberrations was observed in root tip cells of seedlings grown in polluted soil. Among these abnormalities laggards, bridges, stickiness, precocious separation and fragments were the most common. The obtained results demonstrated that heavy metal polluted soils led to a significant MI reduction and CA increase in root tip meristems of Cicer.

  15. A novel Filamentous Flower mutant suppresses brevipedicellus developmental defects and modulates glucosinolate and auxin levels.

    Directory of Open Access Journals (Sweden)

    Scott J Douglas

    Full Text Available BREVIPEDICELLUS (BP encodes a class-I KNOTTED1-like homeobox (KNOX transcription factor that plays a critical role in conditioning a replication competent state in the apical meristem, and it also governs growth and cellular differentiation in internodes and pedicels. To search for factors that modify BP signaling, we conducted a suppressor screen on bp er (erecta plants and identified a mutant that ameliorates many of the pleiotropic defects of the parent line. Map based cloning and complementation studies revealed that the defect lies in the FILAMENTOUS FLOWER (FIL gene, a member of the YABBY family of transcriptional regulators that contribute to meristem organization and function, phyllotaxy, leaf and floral organ growth and polarity, and are also known to repress KNOX gene expression. Genetic and cytological analyses of the fil-10 suppressor line indicate that the role of FIL in promoting growth is independent of its previously characterized influences on meristem identity and lateral organ polarity, and likely occurs non-cell-autonomously from superior floral organs. Transcription profiling of inflorescences revealed that FIL downregulates numerous transcription factors which in turn may subordinately regulate inflorescence architecture. In addition, FIL, directly or indirectly, activates over a dozen genes involved in glucosinolate production in part by activating MYB28, a known activator of many aliphatic glucosinolate biosynthesis genes. In the bp er fil-10 suppressor mutant background, enhanced expression of CYP71A13, AMIDASE1 (AMI and NITRILASE genes suggest that auxin levels can be modulated by shunting glucosinolate metabolites into the IAA biosynthetic pathway, and increased IAA levels in the bp er fil-10 suppressor accompany enhanced internode and pedicel elongation. We propose that FIL acts to oppose KNOX1 gene function through a complex regulatory network that involves changes in secondary metabolites and auxin.

  16. Expression Studies of Gibberellin Oxidases in Developing Pumpkin Seeds1

    Science.gov (United States)

    Frisse, Andrea; Pimenta, Maria João; Lange, Theo

    2003-01-01

    Two cDNA clones, 3-ox and 2-ox, have been isolated from developing pumpkin (Cucurbita maxima) embryos that show significant amino acid homology to gibberellin (GA) 3-oxidases and 2-oxidases, respectively. Recombinant fusion protein of clone 3-ox converted GA12-aldehyde, GA12, GA15, GA24, GA25, and GA9 to GA14-aldehyde, GA14, GA37, GA36, GA13, and GA4, respectively. Recombinant 2-ox protein oxidized GA9, GA4, and GA1 to GA51, GA34, and GA8, respectively. Previously cloned GA 7-oxidase revealed additional 3β-hydroxylation activity of GA12. Transcripts of this gene were identified in endosperm and embryo of the developing seed by quantitative reverse transcriptase-polymerase chain reaction and localized in protoderm, root apical meristem, and quiescent center by in situ hybridization. mRNA of the previously cloned GA 20-oxidase from pumpkin seeds was localized in endosperm and in tissues of protoderm, ground meristem, and cotyledons of the embryo. However, transcripts of the recently cloned GA 20-oxidase from pumpkin seedlings were found all over the embryo, and in tissues of the inner seed coat at the micropylar end. Previously cloned GA 2β,3β-hydroxylase mRNA molecules were specifically identified in endosperm tissue. Finally, mRNA molecules of the 3-ox and 2-ox genes were found in the embryo only. 3-ox transcripts were localized in tissues of cotyledons, protoderm, and inner cell layers of the root apical meristem, and 2-ox transcripts were found in all tissues of the embryo except the root tips. These results indicate tissue-specific GA-biosynthetic pathways operating within the developing seed. PMID:12644672

  17. The effect of CuO NPs on reactive oxygen species and cell cycle gene expression in roots of rice.

    Science.gov (United States)

    Wang, Shuling; Liu, Hanzhu; Zhang, Yuxi; Xin, Hua

    2015-03-01

    To evaluate the effect of CuO nanoparticles (NPs) on root growth, root reactive oxygen species (ROS) production, and the expression of 2 genes (OsCDC2 and OsCYCD) associated with root growth of Oryza sativa (rice), rice roots were treated with 5 mg/L CuO NP suspension, 5 mg/L CuO bulk particle suspension, and 0.27 mg/L CuSO4  · 5H2 O solution, with distilled water as control. The results indicated that CuO NPs and Cu(2+) severely inhibited the elongation and biomass of rice roots after 72-h exposure. Dyeing with 7'-dichlorodihydrofluorescein-diacetate (DCFH-DA) showed that in all 3 treatment groups, the fluorescence was primarily located in the meristem zone, demonstrating that the meristem zone was where ROS were primarily generated. In addition, a significant increase in ROS was detected in the meristem zone of roots treated with the CuO NP suspension and the CuSO4  · 5H2 O solution, both of which greatly influenced the expression level of OsCDC2 and OsCYCD. The impact of Cu(2+) on these 2 genes was smaller than that of CuO NPs. The Cu content in roots of rice after treatment with CuO NPs was much higher than that found after the other treatments, which indicated that CuO NPs may have been absorbed into root tissue. Collectively, these data suggest that growth inhibition, higher ROS production, and gene expression inhibition may be caused not only by the ions themselves, but also the NPs. © 2014 SETAC.

  18. Short day-mediated cessation of growth requires the downregulation of AINTEGUMENTALIKE1 transcription factor in hybrid aspen.

    Directory of Open Access Journals (Sweden)

    Anna Karlberg

    2011-11-01

    Full Text Available Day length is a key environmental cue regulating the timing of major developmental transitions in plants. For example, in perennial plants such as the long-lived trees of the boreal forest, exposure to short days (SD leads to the termination of meristem activity and bud set (referred to as growth cessation. The mechanism underlying SD-mediated induction of growth cessation is poorly understood. Here we show that the AIL1-AIL4 (AINTEGUMENTALIKE transcription factors of the AP2 family are the downstream targets of the SD signal in the regulation of growth cessation response in hybrid aspen trees. AIL1 is expressed in the shoot apical meristem and leaf primordia, and exposure to SD signal downregulates AIL1 expression. Downregulation of AIL gene expression by SDs is altered in transgenic hybrid aspen plants that are defective in SD perception and/or response, e.g. PHYA or FT overexpressors. Importantly, SD-mediated regulation of growth cessation response is also affected by overexpression or downregulation of AIL gene expression. AIL1 protein can interact with the promoter of the key cell cycle genes, e.g. CYCD3.2, and downregulation of the expression of D-type cyclins after SD treatment is prevented by AIL1 overexpression. These data reveal that execution of SD-mediated growth cessation response requires the downregulation of AIL gene expression. Thus, while early acting components like PHYA and the CO/FT regulon are conserved in day-length regulation of flowering time and growth cessation between annual and perennial plants, signaling pathways downstream of SD perception diverge, with AIL transcription factors being novel targets of the CO/FT regulon connecting the perception of SD signal to the regulation of meristem activity.

  19. Evidence that a herbivore tolerance response affects selection on floral traits and inflorescence architecture in purple loosestrife (Lythrum salicaria).

    Science.gov (United States)

    Thomsen, Christina J M; Sargent, Risa D

    2017-06-01

    The study of the evolution of floral traits has generally focused on pollination as the primary driver of selection. However, herbivores can also impose selection on floral traits through a variety of mechanisms, including florivory and parasitism. Less well understood is whether floral and inflorescence architecture traits that influence a plant's tolerance to herbivory, such as compensatory regrowth, alter pollinator-mediated selection. Because herbivore damage to Lythrum salicaria meristems typically leads to an increase in the number of inflorescences and the size of the floral display, an experiment was conducted to test whether simulated herbivory (i.e. clipping the developing meristem) could alter the magnitude or direction of pollinator-mediated selection on a suite of floral and inflorescence architecture traits. Using a pollen supplementation protocol, pollen limitation was compared in the presence and absence of meristem damage in order to quantify any interaction between pollinator and herbivore-mediated selection on floral traits. Surprisingly, in spite of an obvious impact on floral display and architecture, with clipped plants producing more inflorescences and more flowers, there was no difference in pollen limitation between clipped and unclipped plants. Correspondingly, there was no evidence that imposing herbivore damage altered pollinator-mediated selection in this system. Rather, the herbivory treatment alone was found to alter direct selection on floral display, with clipped plants experiencing greater selection for earlier flowering and weaker selection for number of inflorescences when compared with unclipped plants. These findings imply that herbivory on its own can drive selection on plant floral traits and inflorescence architecture in this species, even more so than pollinators. Specifically, herbivory can impose selection on floral traits if such traits influence a plant's tolerance to herbivory, such as through the timing of flowering

  20. 6-benzyladenine metabolism during reinvigoration of mature Pinus radiata buds in vitro.

    Science.gov (United States)

    Zhang, Huaibi; Horgan, Kathryn J; Reynolds, Paul H S; Jameson, Paula E

    2010-04-01

    Maturation or phase change is a serious challenge in the deployment of superior trees of Pinus radiata D. Don because of the difficulties associated with propagation of cuttings from mature trees. We used an in vitro system to study 6-benzyladenine (BA)-induced reinvigoration of the fascicle meristems of mature buds during in vitro culture. Anatomical examinations revealed that BA inhibited the development of secondary needle primordia and 'rejuvenated' the fascicle meristems of the mature bud to produce primary needles, which are characteristic of the juvenile phase in P. radiata. Without BA supplement in the culture media, fascicle primordia continued developing secondary needles and quiescent fascicle meristems. BA metabolite analysis showed that the novel cytokinin pathway reported previously in P. radiata (H. Zhang, K.J. Horgan, P.H.S. Reynolds, G.E. Norris and P.E. Jameson. 2001. Novel cytokinins: The predominant forms in mature buds of Pinus radiata. Physiol. Plant. 112: 127-134) was mirrored in vitro, with BA converted into a variety of metabolites including 6-benzylamino-9-glucopyranosylribosyl-purine and its novel phosphorylated form, 6-benzylamino-9-glucopyranosylribosyl-purine. The culture of mature buds in the presence of BA caused a reduction in the level of endogenous cytokinins, suggesting a direct action of BA itself. Similar correlations are noted between levels of certain metabolites and the maturation status of buds from field-grown trees and buds in culture, indicating that this in vitro system may be a good model for studying the processes of maturation and reinvigoration.

  1. Role of Tulipa gesneriana TEOSINTE BRANCHED1 (TgTB1) in the control of axillary bud outgrowth in bulbs.

    Science.gov (United States)

    Moreno-Pachon, Natalia M; Mutimawurugo, Marie-Chantal; Heynen, Eveline; Sergeeva, Lidiya; Benders, Anne; Blilou, Ikram; Hilhorst, Henk W M; Immink, Richard G H

    2017-12-07

    Tulip vegetative reproduction. Tulips reproduce asexually by the outgrowth of their axillary meristems located in the axil of each bulb scale. The number of axillary meristems in one bulb is low, and not all of them grow out during the yearly growth cycle of the bulb. Since the degree of axillary bud outgrowth in tulip determines the success of their vegetative propagation, this study aimed at understanding the mechanism controlling the differential axillary bud activity. We used a combined physiological and "bottom-up" molecular approach to shed light on this process and found that first two inner located buds do not seem to experience dormancy during the growth cycle, while mid-located buds enter dormancy by the end of the growing season. Dormancy was assessed by weight increase and TgTB1 expression levels, a conserved TCP transcription factor and well-known master integrator of environmental and endogenous signals influencing axillary meristem outgrowth in plants. We showed that TgTB1 expression in tulip bulbs can be modulated by sucrose, cytokinin and strigolactone, just as it has been reported for other species. However, the limited growth of mid-located buds, even when their TgTB1 expression is downregulated, points at other factors, probably physical, inhibiting their growth. We conclude that the time of axillary bud initiation determines the degree of dormancy and the sink strength of the bud. Thus, development, apical dominance, sink strength, hormonal cross-talk, expression of TgTB1 and other possibly physical but unidentified players, all converge to determine the growth capacity of tulip axillary buds.

  2. ARABIDOPSIS HOMOLOG of TRITHORAX1 (ATX1) is required for cell production, patterning, and morphogenesis in root development

    OpenAIRE

    Napsucialy-Mendivil, Selene; Alvarez-Venegas, Raúl; Shishkova, Svetlana; Dubrovsky, Joseph G.

    2014-01-01

    ARABIDOPSIS HOMOLOG of TRITHORAX1 (ATX1/SDG27), a known regulator of flower development, encodes a H3K4histone methyltransferase that maintains a number of genes in an active state. In this study, the role of ATX1 in root development was evaluated. The loss-of-function mutant atx1-1 was impaired in primary root growth. The data suggest that ATX1 controls root growth by regulating cell cycle duration, cell production, and the transition from cell proliferation in the root apical meristem (RAM)...

  3. Genetic improvement of sweet potato through somatic embyrogenesis and in vitro induction of mutations

    International Nuclear Information System (INIS)

    Sonnino, A.; Thinh, N.T.; Santangelo, E.; Mini, P.

    1997-01-01

    Mutation breeding is a promising option for the genetic improvement of sweet potato. Callus induction, somatic embryogenesis and plant regeneration was investigated in twenty-two sweet potato varieties of different origin. Plant regeneration was found to depend on the genotype and composition of the induction medium. The regeneration through somatic embryogenesis induced morphological and physiological changes among the regenerated plants. The irradiation with 30 to 50 Gy of meristems before culture on induction medium inhibited somatic embryogenesis. A number of accessions were evaluated in field trials and showed wide differences in yield. (author). 6 refs, 6 tabs

  4. Water imaging in living plant by nondestructive neutron beam analysis

    International Nuclear Information System (INIS)

    Nakanishi, M. Tomoko

    1998-01-01

    Analysis of biological activity in intact cells or tissues is essential to understand many life processes. Techniques for these in vivo measurements have not been well developed. We present here a nondestructive method to image water in living plants using a neutron beam. This technique provides the highest resolution for water in tissue yet obtainable. With high specificity to water, this neutron beam technique images water movement in seeds or in roots imbedded in soil, as well as in wood and meristems during development. The resolution of the image attainable now is about 15um. We also describe how this new technique will allow new investigations in the field of plant research. (author)

  5. Imaging of water in living plant using neutron beam and positron emitting nuclides

    International Nuclear Information System (INIS)

    Nakanishi, Tomoko M.

    2001-01-01

    Analysis of biological activity in intact cells or tissues is essential to understand many life processes. Techniques for these in vivo measurements have not been well developed. We present here a nondestructive method to image water in living plants using a neutron beam as well as positron emitting nuclides. With high specificity to water, neutron beam technique images water movement in seeds or in roots imbedded in soil, as well as in wood and meristems during development. To know real-time water movement, positron emitting nuclides, 18 F or 15 O was produced by a cyclotron. We present how water uptake activity was shown using these these nuclides. (author)

  6. Learning To Breathe: Developmental Phase Transitions in Oxygen Status.

    Science.gov (United States)

    Considine, Michael J; Diaz-Vivancos, Pedro; Kerchev, Pavel; Signorelli, Santiago; Agudelo-Romero, Patricia; Gibbs, Daniel J; Foyer, Christine H

    2017-02-01

    Plants are developmentally disposed to significant changes in oxygen availability, but our understanding of the importance of hypoxia is almost entirely limited to stress biology. Differential patterns of the abundance of oxygen, nitric oxide ( • NO), and reactive oxygen species (ROS), as well as of redox potential, occur in organs and meristems, and examples are emerging in the literature of mechanistic relationships of these to development. We describe here the convergence of these cues in meristematic and reproductive tissues, and discuss the evidence for regulated hypoxic niches within which oxygen-, ROS-, • NO-, and redox-dependent signalling curate developmental transitions in plants. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Genetic Transformation of Common Bean (Phaseolus vulgaris L. with the Gus Color Marker, the Bar Herbicide Resistance, and the Barley (Hordeum vulgare HVA1 Drought Tolerance Genes

    Directory of Open Access Journals (Sweden)

    Kingdom Kwapata

    2012-01-01

    Full Text Available Five common bean (Phaseolus vulgaris L. varieties including “Condor,” “Matterhorn,” “Sedona,” “Olathe,” and “Montcalm” were genetically transformed via the Biolistic bombardment of the apical shoot meristem primordium. Transgenes included gus color marker which visually confirmed transgenic events, the bar herbicide resistance selectable marker used for in vitro selection of transgenic cultures and which confirmed Liberty herbicide resistant plants, and the barley (Hordeum vulgare late embryogenesis abundant protein (HVA1 which conferred drought tolerance with a corresponding increase in root length of transgenic plants. Research presented here might assist in production of better P. vulgaris germplasm.

  8. Meristematic activity of the Endodermis and the Pericycle in the primary thickening in monocotyledons: considerations on the "PTM"

    Directory of Open Access Journals (Sweden)

    Nanuza L. de Menezes

    2005-06-01

    Full Text Available This paper proposes a new interpretation for primary thickening in monocotyledons. The anatomy of the vegetative organs of the following species was examined: Cephalostemon riedelianus (Rapataceae, Cyperus papyrus (Cyperaceae, Lagenocarpus rigidus, L. junciformis (Cyperaceae, Echinodorus paniculatus (Alismataceae and Zingiber officinale (Zingiberaceae. The endodermis with meristematic activity was observed in the root of all the species, in the stem of Cyperus, Cephalostemum and Lagenocarpus rigidus, and in the leaf trace of Cyperus and leaf of Echinodorus. Considering the continuity of tissues through the root, stem and leaf, the authors conclude that in the stem the pericycle remains active throughout the life of the plant as the generator of the vascular tissue. The "Primary Thickening Meristem" is in fact the pericycle plus the endodermis and its derivatives (or only the pericycle. Close to the stem apex, the assemblage of seems to be a unique meristem, giving rise to the inner cortex and vascular tissues.A proposta deste trabalho é mostrar uma nova interpretação do meristema de espessamento primário em monocotiledôneas. Anatomia dos órgãos vegetativos das seguintes espécies foi examinada: Cephalostemon riedelianus (Rapataceae, Cyperus papyrus (Cyperaceae, Lagenocarpus rigidus, L. Junciformis (Cyperaceae, Echinodorus paniculatus (Alismataceae and Zingiberofficinale (Zingiberaceae. A atividade meristemática da endoderme foi observada nas raizes de todas as espécies, no caule de Cyperus, Cephalostemum e Lagenocarpus rigidus, e no traço foliar de Cyperus e folha de Echinodorus. Considerando a continuidade dos tecidos através da raiz, caule e folha, as autoras concluem que no caule o periciclo permanece ativo durante a vida da planta, como um gerador de tecidos vasculares. O "Meristema de Espessamento Primário" é o periciclo em fase meristemática, juntamente com a endoderme e suas derivadas (ou apenas o periciclo. Próximo ao

  9. Stem Cell-Triggered Immunity via CLV3p-FLS2 Signalling

    OpenAIRE

    Lee, Horim; Chah, Ok-Kyong; Sheen, Jen

    2011-01-01

    Stem cells in the shoot apical meristem (SAM) of plants are the self-renewable reservoir for leaf, stem and flower organogenesis1,2. In nature, disease-free plants can be regenerated from SAM despite infections elsewhere, which underlies a horticultural practice for decades3. However, the molecular basis of the SAM immunity remains enigmatic. Here we show a surprising discovery that the CLAVATA3 peptide (CLV3p), expressed and secreted from the stem cells and functioning as a key regulator of ...

  10. RUG3 and ATM synergistically regulate the alternative splicing of mitochondrial nad2 and the DNA damage response in Arabidopsis thaliana

    OpenAIRE

    Chao Su; Hongtao Zhao; Yankun Zhao; Hongtao Ji; Youning Wang; Liya Zhi; Xia Li

    2017-01-01

    The root apical meristem (RAM) determines both RAM activity and the growth of roots. Plant roots are constantly exposed to adverse environmental stresses that can cause DNA damage or cell cycle arrest in the RAM; however, the mechanism linking root meristematic activity and RAM size to the DNA damage response (DDR) is unclear. Here, we demonstrate that a loss of function in RCC1/UVR8/GEF-Like 3 (RUG3) substantially augmented the DDR and produced a cell cycle arrest in the RAM in rug3 mutant, ...

  11. Conversão in vitro de raízes e folhas de Miltonia flavescens Lindl. em protocormos e regeneração de plantas

    OpenAIRE

    Stefanello,Suzana; Karsten,Juliane; Müller,Taina Soraia; Tomczak,Ana Paula; Bonett,Lucimar Pereira; Schuelter,Adilson Ricken

    2009-01-01

    Objetivou-se, no presente trabalho, avaliar o efeito do 2,4-D e do BAP na formação de protocormos a partir de regiões meristemáticas da raiz e segmentos foliares de Miltonia flavescens Lindl., bem como testar o efeito de concentrações de sacarose e níveis de pH no crescimento in vitro dos protocormos. Ápices radiculares e segmentos de folhas de plantas germinadas in vitro foram inoculados em meio de cultura MS/2 suplementado com 2,4-D e BAP onde permaneceram por 210 dias no escuro, sendo tran...

  12. Ectopic expression of the HAM59 gene causes homeotic transformations of reproductive organs in sunflower (Helianthus annuus L.).

    Science.gov (United States)

    Shulga, O A; Neskorodov, Ya B; Shchennikova, A V; Gaponenko, A K; Skryabin, K G

    2015-01-01

    The function of the HAM59 MADS-box gene in sunflower (Helianthus annuus L.) was studied to clarify homeotic C activity in the Asteraceae plant family. For the first time, transgenic sunflower plants with a modified pattern of HAM59 expression were obtained. It was shown that the HAM59 MADS-box transcription factor did mediate C activity in sunflower. In particular, it participated in termination of the floral meristem, repression of the cadastral function of A-activity, and together with other C-type sunflower protein HAM45-in the specification of the identity of stamens and pistils.

  13. A salt stress-responsive cytokinin receptor homologue isolated from Medicago sativa nodules.

    Science.gov (United States)

    Coba de la Peña, Teodoro; Cárcamo, Claudia B; Almonacid, Luis; Zaballos, Angel; Lucas, M Mercedes; Balomenos, Dimitrios; Pueyo, José J

    2008-03-01

    A new cytokinin receptor homologue, MsHK1, was isolated from Medicago sativa root nodules. MsHK1 expression was induced in alfalfa seedlings by exogenous application of the cytokinin trans-zeatin. Transcript accumulation was detected in different plant organs. MsHK1 expression was induced by salt stress in alfalfa roots, leaves and nodules, and transcript accumulation in the vascular bundles pointed to a putative role in osmosensing for MsHK1 and/or other close cytokinin receptor homologues. Expression in the meristem and the invasion zone of the nodule suggest a role for cytokinin receptors in cytokinin sensing during nodule cell division and differentiation.

  14. Protein intrinsic disorder in Arabidopsis NAC transcription factors

    DEFF Research Database (Denmark)

    O'Shea, Charlotte; Jensen, Mikael Kryger; Stender, Emil G.P.

    2015-01-01

    because of its simple MoRF pattern and its ability to interact with RCD1 (radical-induced cell death 1). Experiments in yeast and thermodynamic characterization suggest that its single MoRF region is sufficient for both transcriptional activation and interaction with RCD1. The remainder of the large......Protein ID (intrinsic disorder) plays a significant, yet relatively unexplored role in transcription factors (TFs). In the present paper, analysis of the transcription regulatory domains (TRDs) of six phylogenetically representative, plant-specific NAC [no apical meristem, ATAF (Arabidopsis...

  15. Somatic embryogenesis in Malaysian cultivars of sweet potato (Ipomoea batatas L.).

    OpenAIRE

    De Silva, Angela Ee

    2017-01-01

    Three Malaysian sweet potato cultivars, namely Ipomoea batatas (L.) cv. Gendut, Jalomas and Telong, were investigated for their abilities to produce somatic embryos. Shoot meristems were used as the starting materials and cultured on Murashige and Skoog basal media (Murashige and Skoog, 1962) in the presence of auxin 2,4-dichlorophenoxyacetic acid (2,4-D) or 2,4,5-trichlorophenoxyacetic acid (2,4,5-T). Auxin 2,4,5-T at 5 µM was most effective for the initiation of primary embryogenic formati...

  16. Main: 1UT7 [RPSD[Archive

    Lifescience Database Archive (English)

    Full Text Available 1UT7 シロイヌナズナ Arabidopsis Arabidopsis thaliana (L.) Heynh. Nac-Domain Containing Pro... Meristem Protein; Synonym: Nam, Anac, Abscisic Acid Responsive Nac, Dicyanoaurate Derivative; Chain: A, B; ...Fragment: Dna-Binding Nac Domain, Residues 1-168; Engineered: Yes; Other_details:...A.Ernst, A.N.Olsen, K.Skriver, S.Larsen, L.Lo Leggio Structure Of The Conserved Domain Of Anac, A Member Of ... Transcription Factor, Dna Binding, Abscisic Acid Response, Arabidopsis Thaliana, Crystal Structure, Nac Domai

  17. Geno-toxicity assay of sediment and water samples from the Upper Silesia post-mining areas, Poland by means of Allium-test

    Energy Technology Data Exchange (ETDEWEB)

    Geras' kin, S.; Oudalova, A.; Michalik, B.; Dikareva, N.; Dikarev, V. [Russian Institute of Agricultural Radiology & Agroecology RAAS, Obninsk (Russian Federation)

    2011-05-15

    Genotoxic potential of two environmental compartments (water and sediment) from the Upper Silesia Coal Basin (USCB), Poland were evaluated and compared by employing root meristem cells of Allium cepa. The clear genotoxic effect of water and sediment sampled was shown, with an important contribution of severe types of cytogenetic abnormalities. The most biologically relevant pollutants were revealed through multivariate statistical analysis of relationships between biological effects registered and the environment contamination. Overall, results of simultaneous use of conventional monitoring methods and biological tests suggested that contemporary levels of persistent pollutants in post-mining areas of the USCB may enhance the risk both for human health and biological components of natural ecosystems.

  18. Influence of Plant Growth Retardants on Quality of Codonopsis Radix

    Directory of Open Access Journals (Sweden)

    Yinyin Liao

    2017-10-01

    Full Text Available Plant growth retardant (PGR refers to organics that can inhibit the cell division of plant stem tip sub-apical meristem cells or primordial meristem cell. They are widely used in the cultivation of rhizomatous functional plants; such as Codonopsis Radix, that is a famous Chinese traditional herb. However, it is still unclear whether PGR affects the medicinal quality of C. Radix. In the present study, amino acid analyses, targeted and non-targeted analyses by ultra-performance liquid chromatography combined with time-of-flight mass spectrometry (UPLC-TOF-MS and gas chromatography-MS were used to analyze and compare the composition of untreated C. Radix and C. Radix treated with PGR. The contents of two key bioactive compounds, lobetyolin and atractylenolide III, were not affected by PGR treatment. The amounts of polysaccharides and some internal volatiles were significantly decreased by PGR treatment; while the free amino acids content was generally increased. Fifteen metabolites whose abundance were affected by PGR treatment were identified by UPLC-TOF-MS. Five of the up-regulated compounds have been reported to show immune activity, which might contribute to the healing efficacy (“buqi” of C. Radix. The results of this study showed that treatment of C. Radix with PGR during cultivation has economic benefits and affected some main bioactive compounds in C. Radix.

  19. Bottlenecks in bog pine multiplication by somatic embryogenesis and their visualization with the environmental scanning electron microscope.

    Science.gov (United States)

    Vlašínová, Helena; Neděla, Vilem; Đorđević, Biljana; Havel, Ladislav

    2017-07-01

    Somatic embryogenesis (SE) is an important biotechnological technique used for the propagation of many pine species in vitro. However, in bog pine, one of the most endangered tree species in the Czech Republic, limitations were observed, which negatively influenced the development and further germination of somatic embryos. Although initiation frequency was very low-0.95 %, all obtained cell lines were subjected to maturation. The best responding cell line (BC1) was used and subjected to six different variants of the maturation media. The media on which the highest number of early-precotyledonary/cotyledonary somatic embryos was formed was supplemented with 121 μM abscisic acid (ABA) and with 6 % maltose. In the end of maturation experiments, different abnormalities in formation of somatic embryos were observed. For visualization and identification of abnormalities in meristem development during proliferation and maturation processes, the environmental scanning electron microscope was used. In comparison to the classical light microscope, the non-commercial environmental scanning electron microscope AQUASEM II has been found as a very useful tool for the quick recognition of apical meristem disruption and abnormal development. To our knowledge, this is the first report discussing somatic embryogenesis in bog pine. Based on this observation, the cultivation procedure could be enhanced and the method for SE of bog pine optimized.

  20. The Populus Class III HD ZIP, popREVOLUTA, Influences Cambium Initiation and Patterning of Woody Stems1[W][OA

    Science.gov (United States)

    Robischon, Marcel; Du, Juan; Miura, Eriko; Groover, Andrew

    2011-01-01

    The secondary growth of a woody stem requires the formation of a vascular cambium at an appropriate position and proper patterning of the vascular tissues derived from the cambium. Class III homeodomain-leucine zipper (HD ZIP) transcription factors have been implicated in polarity determination and patterning in lateral organs and primary vascular tissues and in the initiation and function of shoot apical meristems. We report here the functional characterization of a Populus class III HD ZIP gene, popREVOLUTA (PRE), that demonstrates another role for class III HD ZIPs in regulating the development of cambia and secondary vascular tissues. PRE is orthologous to Arabidopsis (Arabidopsis thaliana) REVOLUTA and is expressed in both the shoot apical meristem and in the cambial zone and secondary vascular tissues. Transgenic Populus expressing a microRNA-resistant form of PRE presents unstable phenotypic abnormalities affecting both primary and secondary growth. Surprisingly, phenotypic changes include abnormal formation of cambia within cortical parenchyma that can produce secondary vascular tissues in reverse polarity. Genes misexpressed in PRE mutants include transcription factors and auxin-related genes previously implicated in class III HD ZIP functions during primary growth. Together, these results suggest that PRE plays a fundamental role in the initiation of the cambium and in regulating the patterning of secondary vascular tissues. PMID:21205615

  1. The Populus class III HD ZIP, popREVOLUTA, influences cambium initiation and patterning of woody stems.

    Science.gov (United States)

    Robischon, Marcel; Du, Juan; Miura, Eriko; Groover, Andrew

    2011-03-01

    The secondary growth of a woody stem requires the formation of a vascular cambium at an appropriate position and proper patterning of the vascular tissues derived from the cambium. Class III homeodomain-leucine zipper (HD ZIP) transcription factors have been implicated in polarity determination and patterning in lateral organs and primary vascular tissues and in the initiation and function of shoot apical meristems. We report here the functional characterization of a Populus class III HD ZIP gene, popREVOLUTA (PRE), that demonstrates another role for class III HD ZIPs in regulating the development of cambia and secondary vascular tissues. PRE is orthologous to Arabidopsis (Arabidopsis thaliana) REVOLUTA and is expressed in both the shoot apical meristem and in the cambial zone and secondary vascular tissues. Transgenic Populus expressing a microRNA-resistant form of PRE presents unstable phenotypic abnormalities affecting both primary and secondary growth. Surprisingly, phenotypic changes include abnormal formation of cambia within cortical parenchyma that can produce secondary vascular tissues in reverse polarity. Genes misexpressed in PRE mutants include transcription factors and auxin-related genes previously implicated in class III HD ZIP functions during primary growth. Together, these results suggest that PRE plays a fundamental role in the initiation of the cambium and in regulating the patterning of secondary vascular tissues.

  2. RNAseq Transcriptional Profiling following Whip Development in Sugarcane Smut Disease

    Science.gov (United States)

    Taniguti, Lucas M.; Peters, Leila P.; Creste, Silvana; Aitken, Karen S.; Van Sluys, Marie-Anne; Kitajima, João P.; Vieira, Maria L. C.; Monteiro-Vitorello, Claudia B.

    2016-01-01

    Sugarcane smut disease is caused by the biotrophic fungus Sporisorium scitamineum. The disease is characterized by the development of a whip-like structure from the primary meristems, where billions of teliospores are produced. Sugarcane smut also causes tillering and low sucrose and high fiber contents, reducing cane productivity. We investigated the biological events contributing to disease symptoms in a smut intermediate-resistant sugarcane genotype by examining the transcriptional profiles (RNAseq) shortly after inoculating the plants and immediately after whip emission. The overall picture of disease progression suggests that premature transcriptional reprogramming of the shoot meristem functions continues until the emergence of the whip. The guidance of this altered pattern is potentially primarily related to auxin mobilization in addition to the involvement of other hormonal imbalances. The consequences associated with whip emission are the modulation of typical meristematic functions toward reproductive organ differentiation, requiring strong changes in carbon partitioning and energy production. These changes include the overexpression of genes coding for invertases and trehalose-6P synthase, as well as other enzymes from key metabolic pathways, such as from lignin biosynthesis. This is the first report describing changes in the transcriptional profiles following whip development, providing a hypothetical model and candidate genes to further study sugarcane smut disease progression. PMID:27583836

  3. [Physiological and structural modifications induced by cadmium-calcium interaction in tomato (Lycopersicon esculentum)].

    Science.gov (United States)

    Boulila Zoghlami, Latifa; Djebali, Wahbi; Chaïbi, Wided; Ghorbel, Mohamed Habib

    2006-09-01

    Tomato seedlings (Lycopersicon esculentum), initially cultivated in a basic nutrient solution during 12 days, were treated with increasing CdCl(2) concentrations for 10 days. The results showed that cadmium inhibited the weight growth depending on the metal concentration and the plant organ. In the presence of 20 microM CdCl(2), the addition of calcium, 0.1 to 10 mM of CaCl(2) in the culture medium, improved especially the biomass production and the mineral composition of the plants in concomitance with an increase in the contents of photosynthetic pigments. Histological study at the hypocotyle level revealed that cadmium (20 microM) induced a restriction of the tissue territories as well as meristem formations differentiating in a root structure. At this concentration, the addition of CaCl(2) (5 microM) was characterized by an opposite effect with absence of meristem structures. The overall results suggest that the alteration of some plant growth process after exposure to cadmium can be attenuated by an adequate calcium contribution in culture medium.

  4. Plant tissue culture independent Agrobacterium tumefaciens mediated In-planta transformation strategy for upland cotton (Gossypium hirsutum

    Directory of Open Access Journals (Sweden)

    Bipinchandra B. Kalbande

    2016-06-01

    Full Text Available A new method of transgenic development called “In-planta” transformation method, where Agrobacterium is used to infect the plantlets but the steps of in vitro regeneration of plants is totally avoided. In this study, we have reported a simple In-planta method for efficient transformation of diploid cotton Gossypium hirsutum cv LRK-516 Anjali using Agrobacterium tumefaciens EHA-105 harbouring recombinant binary vector plasmid pBinAR with Arabidopsis At-NPR1 gene. Four day old plantlets were used for transformation. A vertical cut was made at the junction of cotyledonary leaves, moderately bisecting the shoot tip and exposing meristem cells at apical meristem. This site was infected with Agrobacterium inoculum. The transgenic events obtained were tested positive for the presence of At-NPR1 gene with promoter nptII gene. They are also tested negative for vector backbone integration and Agrobacterium contamination in T0 events. With this method a transformation frequency of 6.89% was reported for the cv LRK-516.

  5. Development of carpels and ovules in Dialypetalanthus fuscescens Kuhlm. (Rubiaceae: an enigmatic taxon

    Directory of Open Access Journals (Sweden)

    Rogério da Costa Figueiredo

    Full Text Available ABSTRACT Dialypetalanthus is a monospecific genus that occurs in the Amazon Basin of Brazil, Bolivia and Peru and occupies a controversial position among the Rubiaceae. We continue this taxonomic discussion with the overall aim of clarifying the systematic position of D. fuscescens within the Rubiaceae. To accomplish this, we analyzed the ontogeny of its gynoecium, in particular the floral meristem, as well as the development of the carpels and cauline placentation. Gynosporogenesis and the differentiation of the carpellary septa and ovules were also described. Dialypetalanthus fuscescens was classified according to evolutionary diagrams found in the literature. The following characteristics were observed in D. fuscescens: 1 permanence of the floral meristem in the central basal part of the early flower bud; 2 dual origin of carpellary septum; 3 trizonate ovular primordia with only one fertile gynospore per ovule; and 4 cellular proliferation in the chalazal region. Embryological results confirm the classification of D. fuscescens in the subfamily Ixoroideae. These results are distinct from any others previously proposed in the evolutionary diagram. Therefore, we conclude that this study has presented evidence strongly suggesting that Dialypetalanthus possesses new morphological-type of ovule we refer to as the Dialypetalanthus-type.

  6. Conservation and divergence of plant LHP1 protein sequences and expression patterns in angiosperms and gymnosperms.

    Science.gov (United States)

    Guan, Hexin; Zheng, Zhengui; Grey, Paris H; Li, Yuhua; Oppenheimer, David G

    2011-05-01

    Floral transition is a critical and strictly regulated developmental process in plants. Mutations in Arabidopsis LIKE HETEROCHROMATIN PROTEIN 1 (AtLHP1)/TERMINAL FLOWER 2 (TFL2) result in early and terminal flowers. Little is known about the gene expression, function and evolution of plant LHP1 homologs, except for Arabidopsis LHP1. In this study, the conservation and divergence of plant LHP1 protein sequences was analyzed by sequence alignments and phylogeny. LHP1 expression patterns were compared among taxa that occupy pivotal phylogenetic positions. Several relatively conserved new motifs/regions were identified among LHP1 homologs. Phylogeny of plant LHP1 proteins agreed with established angiosperm relationships. In situ hybridization unveiled conserved expression of plant LHP1 in the axillary bud/tiller, vascular bundles, developing stamens, and carpels. Unlike AtLHP1, cucumber CsLHP1-2, sugarcane SoLHP1 and maize ZmLHP1, rice OsLHP1 is not expressed in the shoot apical meristem (SAM) and the OsLHP1 transcript level is consistently low in shoots. "Unequal crossover" might have contributed to the divergence in the N-terminal and hinge region lengths of LHP1 homologs. We propose an "insertion-deletion" model for soybean (Glycine max L.) GmLHP1s evolution. Plant LHP1 homologs are more conserved than previously expected, and may favor vegetative meristem identity and primordia formation. OsLHP1 may not function in rice SAM during floral induction.

  7. Influence of caffeine on chromosome lesions induced by chemical mutagens and radiation. 2

    International Nuclear Information System (INIS)

    Dimitrov, B.

    1977-01-01

    The modifying influence of caffeine on γ-ray induced chromosome lesions was studied by chromosome aberration anaysis. Caffeine was applied as a pre- and post-treatment agent following seed (G 1 ) and root meristem (G 2 and S) irradiation of C.capillaris. The frequency of chromosome aberrations induced in G 1 was changed neither by post- nor by pre-treatment with caffeine. This fact proves the lack of caffeine modifying effect. Applied as a post-treatment agent caffeine enhances considerably the frequency of chromosome aberrations induced in root meristem cells. This is especially valid for G 2 irradiated cells, while in S cells no synergistic effect was established between induced chromosome lesions and caffeine. The enhancement of chromosome aberration frequency produced in G 2 shows a clearly manifested dependence on the time (moment) of caffeine application post irradiation. Most considerable enhancement was obtained following post-treatment with caffeine immediately after irradiation. In the following intervals - 15 and 30 min - it decreases progressively, while after 60, 180 and 300 min no enhancing effect is observed. The probable causes for the manifestation and the lack of synergistic effect between chromosome lesions induced in the various mitotic cycle phases and caffeine are discussed. (author)

  8. The tropical cedar tree (Cedrela fissilis Vell., Meliaceae) homolog of the Arabidopsis LEAFY gene is expressed in reproductive tissues and can complement Arabidopsis leafy mutants.

    Science.gov (United States)

    Dornelas, Marcelo Carnier; Rodriguez, Adriana Pinheiro Martinelli

    2006-01-01

    A homolog of FLORICAULA/LEAFY, CfLFY (for Cedrela fissilis LFY), was isolated from tropical cedar. The main stages of the reproductive development in C. fissilis were documented by scanning electron microscopy and the expression patterns of CfLFY were studied during the differentiation of the floral meristems. Furthermore, the biological role of the CfLFY gene was assessed using transgenic Arabidopsis plants. CfLFY showed a high degree of similarity to other plant homologs of FLO/LFY. Southern analysis showed that CfLFY is a single-copy gene in the tropical cedar genome. Northern blot analysis and in situ hybridization results showed that CfLFY was expressed in the reproductive buds during the transition from vegetative to reproductive growth, as well as in floral meristems and floral organs but was excluded from the vegetative apex and leaves. Transgenic Arabidopsis lfy26 mutant lines expressing the CfLFY coding region, under the control of the LFY promoter, showed restored wild-type phenotype. Taken together, our results suggest that CfLFY is a FLO/LFY homolog probably involved in the control of tropical cedar reproductive development.

  9. Characterization of expressed sequence tags from Lilium longiflorum in vernalized and non-vernalized bulbs.

    Science.gov (United States)

    Lugassi-Ben Hamo, Maya; Martin, Carlos Villacorta; Zaccai, Michele

    2015-01-15

    In Lilium longiflorum, vernalization is both an obligatory requirement and the major factor affecting flowering time, however, little is known about the molecular regulation of this mechanism in Lilium and other flowering bulbs. Exposure of L. longiflorum bulbs to 9 weeks at 4°C greatly promoted stem elongation within the bulb, floral transition and flowering. Subtraction libraries of vernalized (V) and non-vernalized (NV) bulb meristems were constructed. 671 and 479 genes were sequenced, from which 72 and 82 proteins were inferred for the NV-V and the V-NV libraries, respectively. Much lower transcription levels and putative gene functions were recorded in the NV-V libraries compared the V-NV libraries. However, a large number of genes annotated to transposable elements (TEs), represented more than 20% of the sequenced cDNA were expressed in the NV-V libraries, as opposed to less than 2% in the V-NV libraries. The expression profile of several genes potentially involved in the vernalization pathway was assessed. Expression of LlSOC1, the lily homologue of SUPPRESSOR OF OVER-EXPRESSION OF CO1 (SOC1), an important flowering gene in several plant species, found in the V-NV library, was highly up-regulated during bulb meristem cold exposure. The subtraction libraries provided a fast tool for relevant gene isolation. Copyright © 2014 Elsevier GmbH. All rights reserved.

  10. EFFECTOR OF TRANSCRIPTION2 is involved in xylem differentiation and includes a functional DNA single strand cutting domain.

    Science.gov (United States)

    Ivanov, Rumen; Tiedemann, Jens; Czihal, Andreas; Schallau, Anna; Diep, Le Hong; Mock, Hans-Peter; Claus, Bernhard; Tewes, Annegret; Bäumlein, Helmut

    2008-01-01

    EFFECTORS OF TRANSCRIPTION2 (ET) are plant-specific regulatory proteins characterized by the presence of two to five C-terminal DNA- and Zn-binding repeats, and a highly conserved cysteine pattern. We describe the structural characterization of the three member Arabidopsis thaliana ET gene family and reveal some allelic sequence polymorphisms. A mutation analysis showed that AtET2 affects the expression of various KNAT genes involved in the maintenance of the undifferentiated state of cambial meristem cells. It also plays a role in the regulation of GA5 (gibberellin 3-beta-dioxygenase) and the cell-cycle-related GASA4. A correlation was established between AtET2 expression and the cellular differentiation state. AtET-GFP fusion proteins shuttle between the cytoplasm and nucleus, with the AtET2 product prevented from entering the nucleus in non-differentiating cells. Within the nucleus, AtET2 probably acts via a single strand cutting domain. A more general regulatory role for ET factors is proposed, governing cell differentiation in cambial meristems, a crucial process for the development of plant vascular tissues.

  11. Control of sweet potato virus diseases.

    Science.gov (United States)

    Loebenstein, Gad

    2015-01-01

    Sweet potato (Ipomoea batatas) is ranked seventh in global food crop production and is the third most important root crop after potato and cassava. Sweet potatoes are vegetative propagated from vines, root slips (sprouts), or tubers. Therefore, virus diseases can be a major constrain, reducing yields markedly, often more than 50%. The main viruses worldwide are Sweet potato feathery mottle virus (SPFMV) and Sweet potato chlorotic stunt virus (SPCSV). Effects on yields by SPFMV or SPCSV alone are minor, or but in complex infection by the two or other viruses yield losses of 50%. The orthodox way of controlling viruses in vegetative propagated crops is by supplying the growers with virus-tested planting material. High-yielding plants are tested for freedom of viruses by PCR, serology, and grafting to sweet potato virus indicator plants. After this, meristem tips are taken from those plants that reacted negative. The meristems were grown into plants which were kept under insect-proof conditions and away from other sweet potato material for distribution to farmers after another cycle of reproduction. © 2015 Elsevier Inc. All rights reserved.

  12. Florigen and anti-florigen - a systemic mechanism for coordinating growth and termination in flowering plants.

    Science.gov (United States)

    Lifschitz, Eliezer; Ayre, Brian G; Eshed, Yuval

    2014-01-01

    Genetic studies in Arabidopsis established FLOWERING LOCUS T (FT) as a key flower-promoting gene in photoperiodic systems. Grafting experiments established unequivocal one-to-one relations between SINGLE FLOWER TRUSS (SFT), a tomato homolog of FT, and the hypothetical florigen, in all flowering plants. Additional studies of SFT and SELF PRUNING (SP, homolog of TFL1), two antagonistic genes regulating the architecture of the sympodial shoot system, have suggested that transition to flowering in the day-neutral and perennial tomato is synonymous with "termination." Dosage manipulation of its endogenous and mobile, graft-transmissible levels demonstrated that florigen regulates termination and transition to flowering in an SP-dependent manner and, by the same token, that high florigen levels induce growth arrest and termination in meristems across the tomato shoot system. It was thus proposed that growth balances, and consequently the patterning of the shoot systems in all plants, are mediated by endogenous, meristem-specific dynamic SFT/SP ratios and that shifts to termination by changing SFT/SP ratios are triggered by the imported florigen, the mobile form of SFT. Florigen is a universal plant growth hormone inherently checked by a complementary antagonistic systemic system. Thus, an examination of the endogenous functions of FT-like genes, or of the systemic roles of the mobile florigen in any plant species, that fails to pay careful attention to the balancing antagonistic systems, or to consider its functions in day-neutral or perennial plants, would be incomplete.

  13. Ectopic expression of a WRKY homolog from Glycine soja alters flowering time in Arabidopsis.

    Science.gov (United States)

    Luo, Xiao; Sun, Xiaoli; Liu, Baohui; Zhu, Dan; Bai, Xi; Cai, Hua; Ji, Wei; Cao, Lei; Wu, Jing; Wang, Mingchao; Ding, Xiaodong; Zhu, Yanming

    2013-01-01

    Flowering is a critical event in the life cycle of plants; the WRKY-type transcription factors are reported to be involved in many developmental processes sunch as trichome development and epicuticular wax loading, but whether they are involved in flowering time regulation is still unknown. Within this study, we provide clear evidence that GsWRKY20, a member of WRKY gene family from wild soybean, is involved in controlling plant flowering time. Expression of GsWRKY20 was abundant in the shoot tips and inflorescence meristems of wild soybean. Phenotypic analysis showed that GsWRKY20 over-expression lines flowered earlier than the wild-type plants under all conditions: long-day and short-day photoperiods, vernalization, or exogenous GA3 application, indicating that GsWRKY20 may mainly be involved in an autonomous flowering pathway. Further analyses by qRT-PCR and microarray suggests that GsWRKY20 accelerating plant flowering might primarily be through the regulation of flowering-related genes (i.e., FLC, FT, SOC1 and CO) and floral meristem identity genes (i.e., AP1, SEP3, AP3, PI and AG). Our results provide the evidence demonstrating the effectiveness of manipulating GsWRKY20 for altering plant flowering time.

  14. The Growth Response of Several Potato Genotypes (Solanum tuberosum L. to Induced Water Stress Using Sorbitol and Polyethylene Glycol

    Directory of Open Access Journals (Sweden)

    Mihaela A. CIOLOCA

    2016-12-01

    Full Text Available The current paper aimed to study the in vitro response of potato genotypes to water stress induced by adding sorbitol and polyethylene glycol in the culture medium. The biological material analysed in the experiment was represented by a Romanian line ‘LP 11-1525/1’ and two isogenic lines ‘LI 101’ and ‘LI 102’. For cultures initiation, the line ‘LP 11-1525/1’ was started from meristems and for the other two genotypes true potato seeds were used. The studied potato genotypes behaved differently depending on the analysed parameters and on the treatment applied for drought tolerance. It was noted that the line ‘LP 11-1525/1’ achieved good results for most of the growth parameters studied, and also the lines derived from true potato seeds behaved well, in some cases even exceeding the line derived from meristems. Of the lines derived from true potato seeds, the best performance was noted for line ‘LI 101-6’ in all the analysed parameters, both on sorbitol and PEG medium. In addition, lines ‘LI 101-7’ and ‘LI 102-4’ achieved good results on both variants of medium used to mediate water stress. Therefore, establishing drought tolerance individuals within populations derived from true potato seeds using sorbitol and polyethylene glycol might be applied.

  15. AtLa1 protein initiates IRES-dependent translation of WUSCHEL mRNA and regulates the stem cell homeostasis of Arabidopsis in response to environmental hazards.

    Science.gov (United States)

    Cui, Yuchao; Rao, Shaofei; Chang, Beibei; Wang, Xiaoshuang; Zhang, Kaidian; Hou, Xueliang; Zhu, Xueyi; Wu, Haijun; Tian, Zhaoxia; Zhao, Zhong; Yang, Chengwei; Huang, Tao

    2015-10-01

    Plant stem cells are hypersensitive to environmental hazards throughout their life cycle, but the mechanism by which plants safeguard stem cell homeostasis in response to environmental hazards is largely unknown. The homeodomain transcription factor WUSCHEL (WUS) protein maintains the stem cell pool in the shoot apical meristem of Arabidopsis. Here, we demonstrate that the translation of WUS mRNA is directed by an internal ribosomal entry site (IRES) located in the 5'-untranslated region. The AtLa1 protein, an RNA-binding factor, binds to the 5'-untranslated region and initiates the IRES-dependent translation of WUS mRNA. Knockdown of AtLa1 expression represses the WUS IRES-dependent translation and leads to the arrest of growth and development. The AtLa1 protein is mainly located in the nucleoplasm. However, environmental hazards promote the nuclear-to-cytoplasmic translocation of the AtLa1 protein, which further enhances the IRES-dependent translation of WUS mRNA. Genetic evidence indicates that the WUS protein increases the tolerance of the shoot apical meristem to environmental hazards. Based on these results, we conclude that the stem cell niche in Arabidopsis copes with environmental hazards by enhancing the IRES-dependent translation of WUS mRNA under the control of the AtLa1 protein. © 2015 John Wiley & Sons Ltd.

  16. Regeneration and genetic transformation of cowpea (Vigna unguiculata Walp.)

    International Nuclear Information System (INIS)

    Filippone, E.; Colucci, G.; Ciardi, F.; Monti, L.

    1997-01-01

    Regeneration of cowpea (Vigna unguiculata Walp.) was achieved through massive bud formation induced in apical and lateral meristems by the herbicide Thidiazuron (TDZ). The effect of TDZ (5, 10, or 20 μM) was tested in vitro on four different cowpea genotypes. Thidiazuron, even at the highest concentration, had no effect on seed germination. After one month of culture, multiple bud cluster formation was observed in all genotypes tested; about 80% of shoot apices regenerated multiple buds, whilst only 34% of cotyledonary nodes behaved in the same way. Histology of regenerating multiple bud clusters revealed that regeneration initiated from pre-existing meristems in the apex and cotyledonary node. Thidiazuron at 10 μM appeared to be the best concentration to produce clusters with high number of buds, ranging from 5 to 10. Shoot elongation occurred only on MS medium without TDZ. On the same medium, 75% of elongated shoots rooted. For genetic transformation of cowpea, a direct DNA transfer methods in plants under in vivo conditions was tested by electroporation of plasmid DNA into the nodal meristematic cells. Some transformed plants were obtained, and produced T 1 transformed progenies; their transgenic nature was confirmed by Southern analysis. (author). 21 refs, 2 figs, 3 tabs

  17. Seasonal changes in the degree of symplasmic continuity between the cells of cambial region of Acer pseudoplatanus and Ulmus minor

    Directory of Open Access Journals (Sweden)

    Katarzyna Sokołowska

    2011-01-01

    Full Text Available The presence of symplasmic isolation and symplasmic continuity which are functional aspects of cell-to-cell communication, had been studied in cambium of Acer pseudoplatanus and Ulmus minor, with hope that uniqueness of this meristem, exemplified by its morphology and seasonal variations in its activity is also manifested in differences in the efficiency of communication between cambial cells during the year. The degree of symplasmic continuity was estimated by loading the fluorescent symplasmic tracer to the stem and following its distribution in a population of cambial cells observed on tangential, transverse and radial sections. In active cambium the tracer did not enter the rays. This suggested that the ray and fusiform cells, growing and dividing intensively at different rates were specifically isolated from each other. In the state of dormancy the tracer was present also in the rays implying continuity between the two types of cambial cells. Temporal restriction in tracer spreading from secondary xylem to cambial region was observed on transverse sections in both physiological states of the meristem. Higher degree of symplasmic isolation in active cambium is, most probably, associated with functional distinctiveness of ray and fusiform cells. We hypothesize further that the symplasmic continuity in dormant cambium results from the open conformation states of plasmodesmata, because the energy costs of these states are low. It is reasonable strategy when cambial cells do not divide and maintenance of their functional individuality is not necessary.

  18. Differential CLE peptide perception by plant receptors implicated from structural and functional analyses of TDIF-TDR interactions

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zhijie; Chakraborty, Sayan; Xu, Guozhou; Kobe, Bostjan

    2017-04-06

    Tracheary Element Differentiation Inhibitory Factor (TDIF) belongs to the family of post-translationally modified CLE (CLAVATA3/embryo surrounding region (ESR)-related) peptide hormones that control root growth and define the delicate balance between stem cell proliferation and differentiation in SAM (shoot apical meristem) or RAM (root apical meristem). In Arabidopsis, Tracheary Element Differentiation Inhibitory Factor Receptor (TDR) and its ligand TDIF signaling pathway is involved in the regulation of procambial cell proliferation and inhibiting its differentiation into xylem cells. Here we present the crystal structures of the extracellular domains (ECD) of TDR alone and in complex with its ligand TDIF resolved at 2.65 Åand 2.75 Å respectively. These structures provide insights about the ligand perception and specific interactions between the CLE peptides and their cognate receptors. Our in vitro biochemical studies indicate that the interactions between the ligands and the receptors at the C-terminal anchoring site provide conserved binding. While the binding interactions occurring at the N-terminal anchoring site dictate differential binding specificities between different ligands and receptors. Our studies will open different unknown avenues of TDR-TDIF signaling pathways that will enhance our knowledge in this field highlighting the receptor ligand interaction, receptor activation, signaling network, modes of action and will serve as a structure function relationship model between the ligand and the receptor for various similar leucine-rich repeat receptor-like kinases (LRR-RLKs).

  19. Root - shoot - signaling in Chenopodium rubrum L. as studied by 15O labeled water uptake

    International Nuclear Information System (INIS)

    Ohya, T.; Hayashi, Y.; Tanoi, K.; Rai, H.; Nakanishi, T.M.; Suzuki, K.; Albrechtova, J.T.P.; Wagner, E.

    2005-01-01

    Full text: It has been demonstrated with C. rubrum that the different organ systems are transmitting surface action potentials which might be the basis for systemic signal transduction. Shoot tip respectively root generated action potentials travel along the stem axis. Shoot tip generated action potentials arriving at the basis can be reflected and travel upwards. The radioactive labeling technique was established at the NIRS in Inage, Japan. About 2 GBq of 15 O labeled Hoagland's solution was supplied to the plant root or cut stem in a phytotron at 25 o C with 45 % of relative humidity and continuous light. By cutting the shoot apical bud and the apices of main side branches the uptake of 15 O labeled water was inhibited in plants with intact roots but not in plants with roots cut. Because of the short half-life of 15 O (2 min), experiments could be repeated in hourly intervals. Cutting the apex probably limits root water uptake via a hydraulic-electrochemical signal. The results are discussed with respect to the significance of a continuous communication between the root system and the shoot apical meristem(s) in the adaptation of plants to their environment. (author)

  20. Energy related germination and survival rates of water-imbibed Arabidopsis seeds irradiated with protons

    International Nuclear Information System (INIS)

    Qin, H.L.; Xue, J.M.; Lai, J.N.; Wang, J.Y.; Zhang, W.M.; Miao, Q.; Yan, S.; Zhao, W.J.; He, F.; Gu, H.Y.; Wang, Y.G.

    2006-01-01

    In order to investigate the influence of ion energy on the germination and survival rates, water-imbibed Arabidopsis seeds were irradiated with protons in atmosphere. The ion fluence used in this experiment was in the range of 4 x 10 9 -1 x 10 14 ions/cm 2 . The ion energy is from 1.1 MeV to 6.5 MeV. According to the structure of the seed and TRIM simulation, the ions with the energy of 6.5 MeV can irradiate the shoot apical meristem directly whereas the ions with the energy of 1.1 MeV cannot. The results showed that both the germination and survival rates decrease while increasing the ion fluence, and the fluence-respond curve for each energy has different character. Besides the shoot apical meristem (SAM), which is generally considered as the main radiobiological target, the existence of a secondary target around SAM is proposed in this paper

  1. Overexpression of Arabidopsis plasmodesmata germin-like proteins disrupts root growth and development.

    Science.gov (United States)

    Ham, Byung-Kook; Li, Gang; Kang, Byung-Ho; Zeng, Fanchang; Lucas, William J

    2012-09-01

    In plants, a population of non-cell-autonomous proteins (NCAPs), including numerous transcription factors, move cell to cell through plasmodesmata (PD). In many cases, the intercellular trafficking of these NCAPs is regulated by their interaction with specific PD components. To gain further insight into the functions of this NCAP pathway, coimmunoprecipitation experiments were performed on a tobacco (Nicotiana tabacum) plasmodesmal-enriched cell wall protein preparation using as bait the NCAP, pumpkin (Cucurbita maxima) PHLOEM PROTEIN16 (Cm-PP16). A Cm-PP16 interaction partner, Nt-PLASMODESMAL GERMIN-LIKE PROTEIN1 (Nt-PDGLP1) was identified and shown to be a PD-located component. Arabidopsis thaliana putative orthologs, PDGLP1 and PDGLP2, were identified; expression studies indicated that, postgermination, these proteins were preferentially expressed in the root system. The PDGLP1 signal peptide was shown to function in localization to the PD by a novel mechanism involving the endoplasmic reticulum-Golgi secretory pathway. Overexpression of various tagged versions altered root meristem function, leading to reduced primary root but enhanced lateral root growth. This effect on root growth was corrected with an inability of these chimeric proteins to form stable PD-localized complexes. PDGLP1 and PDGLP2 appear to be involved in regulating primary root growth by controlling phloem-mediated allocation of resources between the primary and lateral root meristems.

  2. Shortening of the development cycle in winter rape (Brassica napus var. oleifera L. by grafting nonvernalized scions on generative stock

    Directory of Open Access Journals (Sweden)

    Franciszek Dubert

    2013-12-01

    Full Text Available The conditions were investigated under which the development cycle in winter rape could be markedly reduced by grafting. Scions from non vernalized seedlings were grafted onto stock plants beginning their generative phase. Winter rape plants vernalized under natural field conditions and spring rape plants in the initial generative phase were used as stock. Best results were obtained by grafting scions from plants at the stage of 4 leaves, i.e. after 3 weeks of growth, onto winter rape stock. With such scions the effectiveness of graftings was high and seed crops were obtained 170 days earlier than under natural field conditions of growth and 80 days earlier than under artificial conditions. Scions grafted onto winter rape stock produced more siliques than those on spring rape. Grafting of scions after cutting off their apical meristems allowed formation of side shoots and consequently resulted in higher yields of siliques; the formation of siliques, however, was delayed by about 10 days as compared to grafts with apical meristems.

  3. MES buffer affects Arabidopsis root apex zonation and root growth by suppressing superoxide generation in root apex

    Directory of Open Access Journals (Sweden)

    Tomoko eKagenishi

    2016-02-01

    Full Text Available In plants, growth of roots and root hairs is regulated by the fine cellular control of pH and reactive oxygen species. MES, 2-(N-morpholinoethanesulfonic acid as one of the Good’s buffers has broadly been used for buffering medium, and it is thought to suit for plant growth with the concentration at 0.1% (w/v because the buffer capacity of MES ranging pH 5.5-7.0 (for Arabidopsis, pH 5.8. However, many reports have shown that, in nature, roots require different pH values on the surface of specific root apex zones, namely meristem, transition zone and elongation zone. Despite the fact that roots always grow on a media containing buffer molecule, little is known about impact of MES on root growth. Here, we have checked the effects of different concentrations of MES buffer using growing roots of Arabidopsis thaliana. Our results show that 1% of MES significantly inhibited root growth, the number of root hairs and length of meristem, whereas 0.1% promoted root growth and root apex area (region spanning from the root tip up to the transition zone. Furthermore, superoxide generation in root apex disappeared at 1% of MES. These results suggest that MES disturbs normal root morphogenesis by changing the reactive oxygen species (ROS homeostasis in root apex.

  4. MES Buffer Affects Arabidopsis Root Apex Zonation and Root Growth by Suppressing Superoxide Generation in Root Apex.

    Science.gov (United States)

    Kagenishi, Tomoko; Yokawa, Ken; Baluška, František

    2016-01-01

    In plants, growth of roots and root hairs is regulated by the fine cellular control of pH and reactive oxygen species (ROS). MES, 2-(N-morpholino)ethanesulfonic acid as one of the Good's buffers has broadly been used for buffering medium, and it is thought to suit for plant growth with the concentration at 0.1% (w/v) because the buffer capacity of MES ranging pH 5.5-7.0 (for Arabidopsis, pH 5.8). However, many reports have shown that, in nature, roots require different pH values on the surface of specific root apex zones, namely meristem, transition zone, and elongation zone. Despite the fact that roots always grow on a media containing buffer molecule, little is known about impact of MES on root growth. Here, we have checked the effects of different concentrations of MES buffer using growing roots of Arabidopsis thaliana. Our results show that 1% of MES significantly inhibited root growth, the number of root hairs and length of meristem, whereas 0.1% promoted root growth and root apex area (region spanning from the root tip up to the transition zone). Furthermore, superoxide generation in root apex disappeared at 1% of MES. These results suggest that MES disturbs normal root morphogenesis by changing the ROS homeostasis in root apex.

  5. Towards the discovery of novel genetic component involved in stress resistance in Arabidopsis thaliana.

    Science.gov (United States)

    Juraniec, Michal; Lequeux, Hélène; Hermans, Christian; Willems, Glenda; Nordborg, Magnus; Schneeberger, Korbinian; Salis, Pietrino; Vromant, Maud; Lutts, Stanley; Verbruggen, Nathalie

    2014-02-01

    The exposure of plants to high concentrations of trace metallic elements such as copper involves a remodeling of the root system, characterized by a primary root growth inhibition and an increase in the lateral root density. These characteristics constitute easy and suitable markers for screening mutants altered in their response to copper excess. A forward genetic approach was undertaken in order to discover novel genetic factors involved in the response to copper excess. A Cu(2+) -sensitive mutant named copper modified resistance1 (cmr1) was isolated and a causative mutation in the CMR1 gene was identified by using positional cloning and next-generation sequencing. CMR1 encodes a plant-specific protein of unknown function. The analysis of the cmr1 mutant indicates that the CMR1 protein is required for optimal growth under normal conditions and has an essential role in the stress response. Impairment of the CMR1 activity alters root growth through aberrant activity of the root meristem, and modifies potassium concentration and hormonal balance (ethylene production and auxin accumulation). Our data support a putative role for CMR1 in cell division regulation and meristem maintenance. Research on the role of CMR1 will contribute to the understanding of the plasticity of plants in response to changing environments. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

  6. The invention of WUS-like stem cell-promoting functions in plants predates leptosporangiate ferns.

    Science.gov (United States)

    Nardmann, Judith; Werr, Wolfgang

    2012-01-01

    The growth of land plants depends on stem cell-containing meristems which show major differences in their architecture from basal to higher plant species. In Arabidopsis, the stem cell niches in the shoot and root meristems are promoted by WUSCHEL (WUS) and WOX5, respectively. Both genes are members of a non-ancestral clade of the WUS-related homeobox (WOX) gene family, which is absent in extant bryophytes and lycophytes. Our analyses of five fern species suggest that a single WUS orthologue was present in the last common ancestor (LCA) of leptosporangiate ferns and seed plants. In the extant fern Ceratopteris richardii, the WUS pro-orthologue marks the pluripotent cell fate of immediate descendants of the root apical initial, so-called merophytes, which undergo a series of stereotypic cell divisions and give rise to all cell types of the root except the root cap. The invention of a WUS-like function within the WOX gene family in an ancestor of leptosporangiate ferns and seed plants and its amplification and sub-functionalisation to different stem cell niches might relate to the success of seed plants, especially angiosperms.

  7. A dominant mutation of TWISTED DWARF 1 encoding an alpha-tubulin protein causes severe dwarfism and right helical growth in rice.

    Science.gov (United States)

    Sunohara, Hidehiko; Kawai, Takayuki; Shimizu-Sato, Sae; Sato, Yutaka; Sato, Kanna; Kitano, Hidemi

    2009-06-01

    Dwarfism is a common type of mutation in many plant species. The pathways and factors regulating biosynthesis and signaling of several plant growth regulators have been clarified through analyses of dwarf mutants in rice, Arabidopsis, pea, and maize. However, the genetic mechanisms controlling dwarfism are not well characterized, and the causal genes underlying most dwarf mutants are still uncovered. Here, we report a dominant mutant, Twisted dwarf 1-1 (Tid1-1), showing dwarfism and twisted growth in rice. Tid1-1 exhibit right helical growth of the leaves and stem and shortening of the roots. They also show an increased number of cells in the shoot apical meristem. Cells in the leaves of Tid1-1 are often ill-shapen, possibly owing to irregular cell division. Cell elongation in roots is suppressed in the elongation zone, and cells in the root apical meristem are enlarged. Map-based cloning of TID1 revealed that it encodes an alpha-tubulin protein comprising microtubules and is an ortholog of Arabidopsis LEFTY genes. Our analysis of the Tid1-1 mutant revealed that the dynamics of microtubules affects not only anisotropic growth in both dicots and monocots, but also meristematic activity and gross plant morphology.

  8. Differential transcriptome analysis between Populus and its synthesized allotriploids driven by second-division restitution.

    Science.gov (United States)

    Cheng, Shiping; Huang, Zhen; Li, Yun; Liao, Ting; Suo, Yujing; Zhang, Pingdong; Wang, Jun; Kang, Xiangyang

    2015-12-01

    In this report, we compared transcriptomic differences between a synthetic Populus section Tacamahaca triploid driven by second-division restitution and its parents using a high-throughput RNA-seq method. A total of 4,080 genes were differentially expressed between the high-growth vigor allotriploids (SDR-H) and their parents, and 719 genes were non-additively expressed in SDR-H. Differences in gene expression between the allotriploid and male parent were more significant than those between the allotriploid and female parent, which may be caused by maternal effects. We observed 3,559 differentially expressed genes (DEGs) between the SDR-H and male parent. Notably, the genes were mainly involved in metabolic process, cell proliferation, DNA methylation, cell division, and meristem and developmental growth. Among the 1,056 DEGs between SDR-H and female parent, many genes were associated with metabolic process and carbon utilization. In addition, 1,789 DEGs between high- and low-growth vigor allotriploid were mainly associated with metabolic process, auxin poplar transport, and regulation of meristem growth. Our results indicated that the higher poplar ploidy level can generate extensive transcriptomic diversity compared with its parents. Overall, these results increased our understanding of the driving force for phenotypic variation and adaptation in allopolyploids driven by second-division restitution. © 2015 Institute of Botany, Chinese Academy of Sciences.

  9. Morphogenesis of root nodules in white clover. II. The effect of mutation in genes nod IJ of the microsymbiont upon the nodule structure

    Directory of Open Access Journals (Sweden)

    Barbara Łotocka

    2014-01-01

    Full Text Available Morphogenesis of ineffective root nodules initiated on the roots of white clover 'Astra' by the Rhizobium leguminosarum biovar. trifolii strains ANU261 (Tn5 insertion in nod 1 gene and ANU262 (Tn5 insertion in nod J gene was investigated. Following changes were observed, as compared to the wild-type nodulation: the exaggerated, not delayed reaction of root hairs; the delay in nodulation with the number of nodules the same as in plants inoculated with a wild strain; the formation and organization of the nodule primordium not changed in comparison with the wild-type nodules; infection threads abnormally branched and diffusing with bacteria deprived of light zone and enriched with storage material; infected cells of bacteroidal tissue abnormally strongly osmiophilic and only slightly vacuolated; symbiosomes with very narrowed peribacteroidal space, subject to premature degradation; abnormal accumulation of starch in the nodule tissues; nodule development blocked at the stage of laterally situated meristem and single nodule bundle; inhibition of divisions in the meristem and vacuolation of its cells; the appearance of single cells with colonies of saprophytic rhizobia embedded in the fibrillar matrix in the old, degraded regions of the bacteroidal tissue.

  10. Changes in histone H3 and H4 multi-acetylation during natural and forced dormancy break in potato tubers.

    Science.gov (United States)

    David Law, R.; Suttle, Jeffrey C.

    2004-04-01

    The effects of post-harvest storage and dormancy progression on histone acetylation patterns were examined in potato (Solanum tuberosum L. cv. Russet Burbank) tubers. Storage of field-grown tubers at 3 degrees C in the dark resulted in the progressive loss of tuber meristem dormancy, defined as measurable growth after transfer to 20 degrees C for 7 days. Dormancy emergence was concomitant with sustained increases in histone H3.1 and H3.2 multi-acetylation, and with transient increases in H4 multi-acetylation that peaked 4-5 months post-harvest. Treatment of dormant tubers with bromoethane (BE) resulted in rapid loss of dormancy over 9 days. Similar to cold-stored field-grown tubers, dormancy break in BE-treated tubers occurred at the same time as transient rises in H4 and H3.1/3.2 multi-acetylation, peaking at days 1 and 4, respectively. BE treatment also resulted in small increases in RNA synthesis at day 6, and a three-fold, sustained activation of DNA synthesis thereafter. A defined sequence of epigenetic events, beginning with previously characterized transient cytosine demethylation, followed by increased H3 and H4 histone acetylation and ultimately, tuber meristem re-activation, may thus exist in potatoes during dormancy exit and resumption of rapid growth.

  11. Molecule mechanism of stem cells in Arabidopsis thaliana.

    Science.gov (United States)

    Zhang, Wenjin; Yu, Rongming

    2014-07-01

    Plants possess the ability to continually produce new tissues and organs throughout their life. Unlike animals, plants are exposed to extreme variations in environmental conditions over the course of their lives. The vitality of plants is so powerful that they can survive several hundreds of years or even more making it an amazing miracle that comes from plant stem cells. The stem cells continue to divide to renew themselves and provide cells for the formation of leaves, stems, and flowers. Stem cells are not only quiescent but also immortal, pluripotent and homeostatic. Stem cells are the magic cells that repair tissues and regenerate organs. During the past decade, scholars around the world have paid more and more attention toward plant stem cells. At present, the major challenge is in relating molecule action mechanism to root apical meristem, shoot apical meristem and vascular system. The coordination between stem cells maintenance and differentiation is critical for normal plant growth and development. Elements such as phytohormones, transcription factors and some other known or unknown genes cooperate to balance this process. In this review, Arabidopsis thaliana as a pioneer system, we highlight recent developments in molecule modulating, illustrating how plant stem cells generate new mechanistic insights into the regulation of plants growth and development.

  12. Ferns: the missing link in shoot evolution and development

    Directory of Open Access Journals (Sweden)

    Andrew Robert George Plackett

    2015-11-01

    Full Text Available Shoot development in land plants is a remarkably complex process that gives rise to an extreme diversity of forms. Our current understanding of shoot developmental mechanisms comes almost entirely from studies of angiosperms (flowering plants, the most recently diverged plant lineage. Shoot development in angiosperms is based around a layered multicellular apical meristem that produces lateral organs and/or secondary meristems from populations of founder cells at its periphery. In contrast, non-seed plant shoots develop from either single apical initials or from a small population of morphologically distinct apical cells. Although developmental and molecular information is becoming available for non-flowering plants, such as the model moss Physcomitrella patens, making valid comparisons between highly divergent lineages is extremely challenging. As sister group to the seed plants, the monilophytes (ferns and relatives represent an excellent phylogenetic midpoint of comparison for unlocking the evolution of shoot developmental mechanisms, and recent technical advances have finally made transgenic analysis possible in the emerging model fern Ceratopteris richardii. This review compares and contrasts our current understanding of shoot development in different land plant lineages with the aim of highlighting the potential role that the fern C. richardii could play in shedding light on the evolution of underlying genetic regulatory mechanisms.

  13. Dt2 Is a Gain-of-Function MADS-Domain Factor Gene That Specifies Semideterminacy in Soybean[C][W

    Science.gov (United States)

    Ping, Jieqing; Liu, Yunfeng; Sun, Lianjun; Zhao, Meixia; Li, Yinghui; She, Maoyun; Sui, Yi; Lin, Feng; Liu, Xiaodong; Tang, Zongxiang; Nguyen, Hanh; Tian, Zhixi; Qiu, Lijuan; Nelson, Randall L.; Clemente, Thomas E.; Specht, James E.; Ma, Jianxin

    2014-01-01

    Similar to Arabidopsis thaliana, the wild soybeans (Glycine soja) and many cultivars exhibit indeterminate stem growth specified by the shoot identity gene Dt1, the functional counterpart of Arabidopsis TERMINAL FLOWER1 (TFL1). Mutations in TFL1 and Dt1 both result in the shoot apical meristem (SAM) switching from vegetative to reproductive state to initiate terminal flowering and thus produce determinate stems. A second soybean gene (Dt2) regulating stem growth was identified, which, in the presence of Dt1, produces semideterminate plants with terminal racemes similar to those observed in determinate plants. Here, we report positional cloning and characterization of Dt2, a dominant MADS domain factor gene classified into the APETALA1/SQUAMOSA (AP1/SQUA) subfamily that includes floral meristem (FM) identity genes AP1, FUL, and CAL in Arabidopsis. Unlike AP1, whose expression is limited to FMs in which the expression of TFL1 is repressed, Dt2 appears to repress the expression of Dt1 in the SAMs to promote early conversion of the SAMs into reproductive inflorescences. Given that Dt2 is not the gene most closely related to AP1 and that semideterminacy is rarely seen in wild soybeans, Dt2 appears to be a recent gain-of-function mutation, which has modified the genetic pathways determining the stem growth habit in soybean. PMID:25005919

  14. Role of auxin during intercellular infection of Discaria trinervis by Frankia

    Science.gov (United States)

    Imanishi, Leandro; Perrine-Walker, Francine M.; Ndour, Adama; Vayssières, Alice; Conejero, Genevieve; Lucas, Mikaël; Champion, Antony; Laplaze, Laurent; Wall, Luis; Svistoonoff, Sergio

    2014-01-01

    Nitrogen-fixing nodules induced by Frankia in the actinorhizal plant Discaria trinervis result from a primitive intercellular root invasion pathway that does not involve root hair deformation and infection threads. Here, we analyzed the role of auxin in this intercellular infection pathway at the molecular level and compared it with our previous work in the intracellular infected actinorhizal plant Casuarina glauca. Immunolocalisation experiments showed that auxin accumulated in Frankia-infected cells in both systems. We then characterized the expression of auxin transporters in D. trinervis nodules. No activation of the heterologous CgAUX1 promoter was detected in infected cells in D. trinervis. These results were confirmed with the endogenous D. trinervis gene, DtAUX1. However, DtAUX1 was expressed in the nodule meristem. Consistently, transgenic D. trinervis plants containing the auxin response marker DR5:VENUS showed expression of the reporter gene in the meristem. Immunolocalisation experiments using an antibody against the auxin efflux carrier PIN1, revealed the presence of this transporter in the plasma membrane of infected cells. Finally, we used in silico cellular models to analyse auxin fluxes in D. trinervis nodules. Our results point to the existence of divergent roles of auxin in intercellularly- and intracellularly-infected actinorhizal plants, an ancestral infection pathways leading to root nodule symbioses. PMID:25191330

  15. Ectopic Expression of a WRKY Homolog from Glycine soja Alters Flowering Time in Arabidopsis

    Science.gov (United States)

    Liu, Baohui; Zhu, Dan; Bai, Xi; Cai, Hua; Ji, Wei; Cao, Lei; Wu, Jing; Wang, Mingchao; Ding, Xiaodong; Zhu, Yanming

    2013-01-01

    Flowering is a critical event in the life cycle of plants; the WRKY-type transcription factors are reported to be involved in many developmental processes sunch as trichome development and epicuticular wax loading, but whether they are involved in flowering time regulation is still unknown. Within this study, we provide clear evidence that GsWRKY20, a member of WRKY gene family from wild soybean, is involved in controlling plant flowering time. Expression of GsWRKY20 was abundant in the shoot tips and inflorescence meristems of wild soybean. Phenotypic analysis showed that GsWRKY20 over-expression lines flowered earlier than the wild-type plants under all conditions: long-day and short-day photoperiods, vernalization, or exogenous GA3 application, indicating that GsWRKY20 may mainly be involved in an autonomous flowering pathway. Further analyses by qRT-PCR and microarray suggests that GsWRKY20 accelerating plant flowering might primarily be through the regulation of flowering-related genes (i.e., FLC, FT, SOC1 and CO) and floral meristem identity genes (i.e., AP1, SEP3, AP3, PI and AG). Our results provide the evidence demonstrating the effectiveness of manipulating GsWRKY20 for altering plant flowering time. PMID:23991184

  16. Auxin regulation of Arabidopsis flower development involves members of the AINTEGUMENTA-LIKE/PLETHORA (AIL/PLT) family.

    Science.gov (United States)

    Krizek, Beth A

    2011-06-01

    Auxin is an important regulator of many aspects of plant growth and development. During reproductive development, auxin specifies the site of flower initiation and subsequently regulates organ growth and patterning as well as later events that determine reproductive success. Underlying auxin action in plant tissues is its uneven distribution, resulting in groups of cells with high auxin levels (auxin maxima) or graded distributions of the hormone (auxin gradients). Dynamic auxin distribution within the periphery of the inflorescence meristems specifies the site of floral meristem initiation, while auxin maxima present at the tips of developing floral organ primordia probably mediate organ growth and patterning. The molecular means by which auxin accumulation patterns are converted into developmental outputs in flowers is not well understood. Members of the AINTEGUMENTA-LIKE/PLETHORA (AIL/PLT) transcription factor family are important developmental regulators in both roots and shoots. In roots, the expression of two AIL/PLT genes is regulated by auxin and these genes feed back to regulate auxin distribution. Here, several aspects of flower development involving both auxin and AIL/PLT activity are described, and evidence linking AIL/PLT function with auxin distribution in reproductive tissues is presented.

  17. Coordination of growth in root and shoot apices by AIL/PLT transcription factors.

    Science.gov (United States)

    Scheres, Ben; Krizek, Beth A

    2018-02-01

    Growth at the root tip and organ generation at the shoot tip depend on the proper functioning of apical meristems and the transitioning of meristematic cell descendants from a proliferating state to cell elongation and differentiation. Members of the AINTEGUMENTA-LIKE/PLETHORA (AIL/PLT) transcription factor family, a clade of two-AP2 domain proteins, specify both stem cell fate and control cellular progression of stem cell daughter cells toward differentiation. Here we highlight the importance of an AIL/PLT protein gradient in controlling distinct cellular behaviors in the root through the regulation of distinct targets in different parts of the root tip. Within the shoot, AIL/PLT proteins also promote organ growth and inhibit differentiation pointing to conserved roles in meristem function. However, they exhibit unequal genetic redundancy in these functions and do not always act in a purely additive manner. Differences in AIL/PLT regulation and perhaps transcriptional targets in roots and shoots suggest that these growth regulators have adapted to mediate growth control in distinct ways in these organ systems. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  18. Diversity and dynamics of plant genome size: an example of polysomaty from a cytogenetic study of Tahitian vanilla (Vanilla xtahitensis, Orchidaceae).

    Science.gov (United States)

    Lepers-Andrzejewski, Sandra; Siljak-Yakovlev, Sonja; Brown, Spencer C; Wong, Maurice; Dron, Michel

    2011-06-01

    Abnormal mitotic behavior with somatic aneuploidy and partial endoreplication were previously reported for the first time in the plant kingdom in Vanilla planifolia. Because vanilla plants are vegetatively propagated, such abnormalities have been transmitted. This study aimed to determine whether mitotic abnormalities also occur in Vanilla hybrid or are suppressed by sexual reproduction. Twenty-eight accessions of Vanilla ×tahitensis, one V. planifolia, and hybrid V. planifolia × V. ×tahitensis were analyzed by chromosome counts, cytometry, and fluorescent in situ hybridization of 18S-5.8S-26S rDNA. In a single root meristem of V. ×tahitensis, chromosome number varied from 22 to 31 in diploids (mean 2C = 5.23 pg), 31 to 41 in triploids (2C = 7.82 pg) and 43 to 60 in tetraploids (2C = 10.27 pg). Morphological diversity is apparently related to ploidy changes. Aneuploidy and partial (asymmetrical) endoreduplication were observed in root meristems of both V. ×tahitensis and the hybrid V. planifolia × V. ×tahitensis, but pollen grains had the euploid chromosome number (n = 15 in diploids). Genome irregularities may be transmitted not only during vegetative propagation but also by sexual reproduction in Vanilla. However, there must be a complex regulation of genome size and organization between the aneuploidy in somatic tissues and subsequently euploid gametic tissue. This is a novel example of polysomaty with developmentally regulated partial endoreplication.

  19. Arabidopsis thaliana ICE2 gene: phylogeny, structural evolution and functional diversification from ICE1.

    Science.gov (United States)

    Kurbidaeva, Amina; Ezhova, Tatiana; Novokreshchenova, Maria

    2014-12-01

    The ability to tolerate environmental stresses is crucial for all living organisms, and gene duplication is one of the sources for evolutionary novelties. Arabidopsis thaliana INDUCER OF CBF EXPRESSION1 and 2 (ICE1 and ICE2) encode MYC-type bHLH (basic helix-loop-helix) transcription factors. They confer cold stress tolerance by induction of the CBF/DREB1 regulon and regulate stomata formation. Although ICE2 is closely related to ICE1, its origin and role in cold response remains uncertain. Here, we used a bioinformatics/phylogenetic approach to uncover the ICE2 evolutionary history, structural evolution and functional divergence from the putative ancestral gene. Sequence diversification from ICE1 included the gain of cis-acting elements in ICE2 promoter sequence that may provide meristem-specific and defense-related gene expression. By analyzing transgenic Arabidopsis lines with ICE2 over-expression we showed that it contributes to stomata formation, flowering time regulation and cold response. Constitutive ICE2 expression led to induced meristem freezing tolerance, resulting from activation of CBF1 and CBF3 genes and ABA biosynthesis by NCED3 induction. We presume that ICE2 gene has originated from a duplication event about 17.9MYA followed by sub- and neofunctionalization of the ancestral ICE1 gene. Moreover, we predict its role in pathogen resistance and flowering time regulation. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  20. TIVIDADE RESPIRATÓRIA DE MERISTEMAS APICAIS DE RAMOS PLAGIOTRÓPICOS DE Araucaria angustifolia (Bertol. Kuntze

    Directory of Open Access Journals (Sweden)

    Gabriely Pinto Pereira

    2016-01-01

    Full Text Available Araucaria angustifolia decreases its growth ratio during the fall and winter in response to adverse environmental conditions such as in temperate fruits where bud dormancy as a survival startegy. The aim of this study was to evaluate the dynamics of the respiratory activity of apical meristems of plagiotropic branches of Araucaria angustifolia . To determine the respiratory activity, samples with 0.4 g of apical buds of plagiotropic branches of young and adult plants were collected. These buds were maintained during two hours in 5 mL of 2,3,5-triphenyl tetrazolium chloride (1.2% in a growth room at 25 °C. Then, it was maintained during one hour in 4 mL of absolute ethyl alcohol and then the absorbance was determined by reading in spectrophotometer at 560 nm. The respiratory activity of apical meristems of plagiotropic branches of Araucaria angustifolia changed during the year, reducing in mid-spring and become lower in the winter in both young and adult plants. Adult plants remained with lower respiratory activity for a longer period, until the beginning of summer.

  1. Transformation of Oats and Its Application to Improving Osmotic Stress Tolerance

    Science.gov (United States)

    Maqbool, Shahina B.; Zhong, Heng; Oraby, Hesham F.; Sticklen, Mariam B.

    Oat (Avena sativa L.), a worldwide temperate cereal crop, is deficient in tolerance to osmotic stress due to drought and/or salinity. To genetically transform the available commercial oat cultivars, a genotype-independent and efficient regeneration system from shoot apical meristems was developed using four oat cultivars: Prairie, Porter, Ogle, and Pacer. All these oat cultivars generated a genotype-independent in vitro differentiated multiple shoots from shoot apical meristems at a high frequency. Using this system, three oat cultivars were genetically co-transformed with pBY520 (containing hva1 and bar) and pAct1-D (containing gus) using biolistic™ bombardment. Transgenic plants were selected and regenerated using herbicide resistance and GUS as a marker. Molecular and biochemical analyses of putative transgenic plants confirmed the co-integration of hva1 and bar genes with a frequency of 100%, and 61.6% of the transgenic plants carried all three genes (hva1, bar and gus). Further analyses of R0, R1, and R2 progenies confirmed stable integration, expression, and Mendalian inheritance for all transgenes. Histochemical analysis of GUS protein in transgenic plants showed a high level of GUS expression in vascular tissues and in the pollen grains of mature flowers. Immunochemical analysis of transgenic plants indicated a constitutive expression of hva1 at all developmental stages. However, the level of HVA1 was higher during the early seedling stages.

  2. Occurrence of Bacillus amyloliquefaciens as a systemic endophyte of vanilla orchids.

    Science.gov (United States)

    White, James F; Torres, Mónica S; Sullivan, Raymond F; Jabbour, Rabih E; Chen, Qiang; Tadych, Mariusz; Irizarry, Ivelisse; Bergen, Marshall S; Havkin-Frenkel, Daphna; Belanger, Faith C

    2014-11-01

    We report the occurrence of Bacillus amyloliquefaciens in vanilla orchids (Vanilla phaeantha) and cultivated hybrid vanilla (V. planifolia × V. pompona) as a systemic bacterial endophyte. We determined with light microscopy and isolations that tissues of V. phaeantha and the cultivated hybrid were infected by a bacterial endophyte and that shoot meristems and stomatal areas of stems and leaves were densely colonized. We identified the endophyte as B. amyloliquefaciens using DNA sequence data. Since additional endophyte-free plants and seed of this orchid were not available, additional studies were performed on surrogate hosts Amaranthus caudatus, Ipomoea tricolor, and I. purpurea. Plants of A. caudatus inoculated with B. amyloliquefaciens demonstrated intracellular colonization of guard cells and other epidermal cells, confirming the pattern observed in the orchids. Isolations and histological studies suggest that the bacterium may penetrate deeply into developing plant tissues in shoot meristems, forming endospores in maturing tissues. B. amyloliquefaciens produced fungal inhibitors in culture. In controlled experiments using morning glory seedlings we showed that the bacterium promoted seedling growth and reduced seedling necrosis due to pathogens. We detected the gene for phosphopantetheinyl transferase (sfp), an enzyme in the pathway for production of antifungal lipopeptides, and purified the lipopeptide "surfactin" from cultures of the bacterium. We hypothesize that B. amyloliquefaciens is a robust endophyte and defensive mutualist of vanilla orchids. Whether the symbiosis between this bacterium and its hosts can be managed to protect vanilla crops from diseases is a question that should be evaluated in future research. © 2014 Wiley Periodicals, Inc.

  3. Change of mitotic behavior and ultra structure of 'Fuju' (Citrus reticulata Blanco) stem-apex clones after space flight

    International Nuclear Information System (INIS)

    Wu Rujian; Huang Jinghao; Wen Shouxing; Cai Zijian; Luo Tuyan; Chen Liangfeng; Wang Zhouwen

    2011-01-01

    By using conventional squash stain technique and ultrathin sectioning technique, the effects of space flight on mitotic behavior and ultrastructure were studied in the shoot apical meristem of 'Fuju' (Citrus reticulata Blanco), which had been carried by China's seed-breeding satellite, Shijian-8. The results showed that space flight had effect on the mutagenesis of stem-apical meristem. Abnormal mitosis with various degrees had been detected in 13 mutant clones, of which mitotic aberrations in clone '08004' were significantly higher than the others. The aberration rate of numerical abnormalities of chromosomes at metaphase, lagging chromosome, micronucleus, C-spindle, S-spindle and polyarch spindle in the clone '08004' was 0.34%, 0.669%, 0.86%, 0.17%, 1.20% and 1.03%, respectively. The ultrastructure of mesophyll cell in most clones was unchanged, but nucleus chromatin agglutination, chloroplast thylakoid disintegrated, autophagosome appeared, cell vacuolated, plasmolysis and the formation of apoptotic body were found in the clone '08004', suggesting that programmed cell death (PCD) Nevertheless, no change in the mitochondrial structure was observed until terminal phase of PCD. (authors)

  4. Europium Uptake and Partitioning in Oat (Avena sativa) Roots as studied By Laser-Induced Fluorescence Spectroscopy and Confocal Microscopy Profiling Technique

    International Nuclear Information System (INIS)

    Fellows, Robert J.; Wang, Zheming; Ainsworth, Calvin C.

    2003-01-01

    The uptake of Eu3+ by elongating oat plant roots was studied by fluorescence spectroscopy, fluorescence lifetime measurement, as well as laser excitation time-resolved confocal fluorescence profiling technique. The results of this work indicated that the initial uptake of Eu(III) by oat root was most evident within the apical meristem of the root just proximal to the root cap. Distribution of assimilated Eu(III) within the roots differentiation and elongation zone was non-uniform. Higher concentrations were observed within the vascular cylinder, specifically in the phloem and developing xylem parenchyma. Elevated levels of the metal were also observed in the root hairs of the mature root. The concentration of assimilated Eu3+ dropped sharply from the apical meristem to the differentiation and elongation zone and then gradually decreased as the distance from the root cap increased. Fluorescence spectroscopic characteristics of the assimilated Eu3+ suggested that the Eu3+ exists a s inner-sphere mononuclear complexes inside the root. This work has also demonstrated the effectiveness of a time-resolved Eu3+ fluorescence spectroscopy and confocal fluorescence profiling techniques for the in vivo, real-time study of metal[Eu3+] accumulation by a functioning intact plant root. This approach can prove valuable for basic and applied studies in plant nutrition and environmental uptake of actinide radionuclides

  5. Shoot-tip cryopreservation by droplet vitrification of Byrsonima intermedia A. Juss.: a woody tropical and medicinal plant species from Brazilian cerrado.

    Science.gov (United States)

    Silva, L C; Paiva, R; Swennen, R; Andre, E; Panis, B

    2013-01-01

    Cryopreservation of plant species is poorly investigated in Brazil. The aim of this study was to cryopreserve Byrsonima intermedia shoot apical meristems through droplet vitrification. A culture medium for shoot-tips growth was established using the Woody Plant Medium supplemented with 2.22 uM 6-benzylaminopurine. Excised shoot-tips were subjected to pre-culture and/or post-culture treatments on Murashige and Skoog medium with 0.3 M sucrose for 24 h prior dehydration on PVS2 at 0°C for 15, 30 or 45 minutes prior to plunging in liquid nitrogen. The effect of 15 days of shoot pre-growth on a high osmotic medium (0.3 M sucrose or 0.21 M sorbitol + 0.09 M sucrose) prior to meristem excision and cryopreservation was also investigated. Pre-culturing shoot-tips on 0.3 M sucrose for 24 h prior to cryopreservation increased the regrowth level after thawing to 90%. Shoot-tips excised from shoots pre-grown on MS + 0.21 M sorbitol + 0.09 M sucrose for 15 days presented a satisfactory regrowth level (67%).

  6. Characterization and expression of a Pinus radiata putative ortholog to the Arabidopsis SHORT-ROOT gene.

    Science.gov (United States)

    Solé, Alicia; Sánchez, Conchi; Vielba, Jesús M; Valladares, Silvia; Abarca, Dolores; Díaz-Sala, Carmen

    2008-11-01

    We characterized a Pinus radiata D. Don putative ortholog to the Arabidopsis thaliana (L.) Heynh. SHORT--ROOT gene (AtSHR) and analyzed its expression in different organs during vegetative development and in response to exogenous auxin during adventitious rooting. The predicted protein sequence contained domains characteristic of the GRAS protein family and showed a strong similarity to the SHORT--ROOT (SHR) proteins. Quantitative reverse transcriptase--polymerase chain reaction (qRT-PCR) and in situ hybridization showed that the gene is predominantly expressed in roots, root primordia and in the cambial region of hypocotyl cuttings. Increased mRNA levels were observed, independently of the presence or absence of exogenous auxin, in the cambial region and rooting competent cells of hypocotyl cuttings within the first 24 h of adventitious rooting, before the activation of cell divisions and the organization of the adventitious root meristem. The expression pattern in organs and during adventitious rooting was similar to that of a Pinus radiata SCARECROW-LIKE (PrSCL1) gene, except that PrSCL1 is induced in response to exogenous auxin. Results suggest that the Pinus radiata SHORT-ROOT (PrSHR) gene has a role in root meristem formation and maintenance and in the cambial region of hypocotyl cuttings.

  7. RNAseq Transcriptional Profiling following Whip Development in Sugarcane Smut Disease.

    Directory of Open Access Journals (Sweden)

    Patricia D C Schaker

    Full Text Available Sugarcane smut disease is caused by the biotrophic fungus Sporisorium scitamineum. The disease is characterized by the development of a whip-like structure from the primary meristems, where billions of teliospores are produced. Sugarcane smut also causes tillering and low sucrose and high fiber contents, reducing cane productivity. We investigated the biological events contributing to disease symptoms in a smut intermediate-resistant sugarcane genotype by examining the transcriptional profiles (RNAseq shortly after inoculating the plants and immediately after whip emission. The overall picture of disease progression suggests that premature transcriptional reprogramming of the shoot meristem functions continues until the emergence of the whip. The guidance of this altered pattern is potentially primarily related to auxin mobilization in addition to the involvement of other hormonal imbalances. The consequences associated with whip emission are the modulation of typical meristematic functions toward reproductive organ differentiation, requiring strong changes in carbon partitioning and energy production. These changes include the overexpression of genes coding for invertases and trehalose-6P synthase, as well as other enzymes from key metabolic pathways, such as from lignin biosynthesis. This is the first report describing changes in the transcriptional profiles following whip development, providing a hypothetical model and candidate genes to further study sugarcane smut disease progression.

  8. Floral Induction in Arabidopsis by FLOWERING LOCUS T Requires Direct Repression of BLADE-ON-PETIOLE Genes by the Homeodomain Protein PENNYWISE1[OPEN

    Science.gov (United States)

    Andrés, Fernando; Romera-Branchat, Maida; Martínez-Gallegos, Rafael; Patel, Vipul; Schneeberger, Korbinian; Jang, Seonghoe; Altmüller, Janine; Nürnberg, Peter; Coupland, George

    2015-01-01

    Flowers form on the flanks of the shoot apical meristem (SAM) in response to environmental and endogenous cues. In Arabidopsis (Arabidopsis thaliana), the photoperiodic pathway acts through FLOWERING LOCUS T (FT) to promote floral induction in response to day length. A complex between FT and the basic leucine-zipper transcription factor FD is proposed to form in the SAM, leading to activation of APETALA1 and LEAFY and thereby promoting floral meristem identity. We identified mutations that suppress FT function and recovered a new allele of the homeodomain transcription factor PENNYWISE (PNY). Genetic and molecular analyses showed that ectopic expression of BLADE-ON-PETIOLE1 (BOP1) and BOP2, which encode transcriptional coactivators, in the SAM during vegetative development, confers the late flowering of pny mutants. In wild-type plants, BOP1 and BOP2 are expressed in lateral organs close to boundaries of the SAM, whereas in pny mutants, their expression occurs in the SAM. This ectopic expression lowers FD mRNA levels, reducing responsiveness to FT and impairing activation of APETALA1 and LEAFY. We show that PNY binds to the promoters of BOP1 and BOP2, repressing their transcription. These results demonstrate a direct role for PNY in defining the spatial expression patterns of boundary genes and the significance of this process for floral induction by FT. PMID:26417007

  9. An evolutionarily conserved gene, FUWA, plays a role in determining panicle architecture, grain shape and grain weight in rice.

    Science.gov (United States)

    Chen, Jun; Gao, He; Zheng, Xiao-Ming; Jin, Mingna; Weng, Jian-Feng; Ma, Jin; Ren, Yulong; Zhou, Kunneng; Wang, Qi; Wang, Jie; Wang, Jiu-Lin; Zhang, Xin; Cheng, Zhijun; Wu, Chuanyin; Wang, Haiyang; Wan, Jian-Min

    2015-08-01

    Plant breeding relies on creation of novel allelic combinations for desired traits. Identification and utilization of beneficial alleles, rare alleles and evolutionarily conserved genes in the germplasm (referred to as 'hidden' genes) provide an effective approach to achieve this goal. Here we show that a chemically induced null mutation in an evolutionarily conserved gene, FUWA, alters multiple important agronomic traits in rice, including panicle architecture, grain shape and grain weight. FUWA encodes an NHL domain-containing protein, with preferential expression in the root meristem, shoot apical meristem and inflorescences, where it restricts excessive cell division. Sequence analysis revealed that FUWA has undergone a bottleneck effect, and become fixed in landraces and modern cultivars during domestication and breeding. We further confirm a highly conserved role of FUWA homologs in determining panicle architecture and grain development in rice, maize and sorghum through genetic transformation. Strikingly, knockdown of the FUWA transcription level by RNA interference results in an erect panicle and increased grain size in both indica and japonica genetic backgrounds. This study illustrates an approach to create new germplasm with improved agronomic traits for crop breeding by tapping into evolutionary conserved genes. © 2015 The Authors The Plant Journal © 2015 John Wiley & Sons Ltd.

  10. ADP1 Affects Plant Architecture by Regulating Local Auxin Biosynthesis

    Science.gov (United States)

    Li, Shibai; Qin, Genji; Novák, Ondřej; Pěnčík, Aleš; Ljung, Karin; Aoyama, Takashi; Liu, Jingjing; Murphy, Angus; Gu, Hongya; Tsuge, Tomohiko; Qu, Li-Jia

    2014-01-01

    Plant architecture is one of the key factors that affect plant survival and productivity. Plant body structure is established through the iterative initiation and outgrowth of lateral organs, which are derived from the shoot apical meristem and root apical meristem, after embryogenesis. Here we report that ADP1, a putative MATE (multidrug and toxic compound extrusion) transporter, plays an essential role in regulating lateral organ outgrowth, and thus in maintaining normal architecture of Arabidopsis. Elevated expression levels of ADP1 resulted in accelerated plant growth rate, and increased the numbers of axillary branches and flowers. Our molecular and genetic evidence demonstrated that the phenotypes of plants over-expressing ADP1 were caused by reduction of local auxin levels in the meristematic regions. We further discovered that this reduction was probably due to decreased levels of auxin biosynthesis in the local meristematic regions based on the measured reduction in IAA levels and the gene expression data. Simultaneous inactivation of ADP1 and its three closest homologs led to growth retardation, relative reduction of lateral organ number and slightly elevated auxin level. Our results indicated that ADP1-mediated regulation of the local auxin level in meristematic regions is an essential determinant for plant architecture maintenance by restraining the outgrowth of lateral organs. PMID:24391508

  11. The flux-based PIN allocation mechanism can generate either canalyzed or diffuse distribution patterns depending on geometry and boundary conditions.

    Directory of Open Access Journals (Sweden)

    Michael Luke Walker

    Full Text Available Growth and morphogenesis in plants require controlled transport of the plant hormone auxin. An important participant is the auxin effluxing protein PIN, whose polarized subcellular localization allows it to effectively transport auxin large distances through tissues. The flux-based model, in which auxin flux through a wall stimulates PIN allocation to that wall, is a dominant contender among models determining where and in what quantity PIN is allocated to cell walls. In this paper we characterise the behaviour of flux-based PIN allocation models in various tissues of the shoot apical meristem. Arguing from both mathematical analysis and computer simulations, we describe the natural behaviours of this class of models under various circumstances. In particular, we demonstrate the important dichotomy between sink- and source- driven systems, and show that both diffuse and canalized PIN distributions can be generated simultaneously in the same tissue, without model hybridization or variation of PIN-related parameters. This work is performed in the context of the shoot apical and floral meristems and is applicable to the construction of a unified PIN allocation model.

  12. Hormone symphony during root growth and development.

    Science.gov (United States)

    Garay-Arroyo, Adriana; De La Paz Sánchez, María; García-Ponce, Berenice; Azpeitia, Eugenio; Alvarez-Buylla, Elena R

    2012-12-01

    Hormones regulate plant growth and development in response to external environmental stimuli via complex signal transduction pathways, which in turn form complex networks of interaction. Several classes of hormones have been reported, and their activity depends on their biosynthesis, transport, conjugation, accumulation in the vacuole, and degradation. However, the activity of a given hormone is also dependent on its interaction with other hormones. Indeed, there is a complex crosstalk between hormones that regulates their biosynthesis, transport, and/or signaling functionality, although some hormones have overlapping or opposite functions. The plant root is a particularly useful system in which to study the complex role of plant hormones in the plastic control of plant development. Physiological, cellular, and molecular genetic approaches have been used to study the role of plant hormones in root meristem homeostasis. In this review, we discuss recent findings on the synthesis, signaling, transport of hormones and role during root development and examine the role of hormone crosstalk in maintaining homeostasis in the apical root meristem. Copyright © 2012 Wiley Periodicals, Inc.

  13. Assessing duplication and loss of APETALA1/FRUITFULL homologs in Ranunculales

    Directory of Open Access Journals (Sweden)

    Natalia ePabon-Mora

    2013-09-01

    Full Text Available Gene duplication and loss provide raw material for evolutionary change within organismal lineages as functional diversification of gene copies provide a mechanism for phenotypic variation. Here we focus on the APETALA1/FRUITFULL MADS-box gene lineage evolution. AP1/FUL genes are angiosperm-specific and have undergone several duplications. By far the most significant one is the core-eudicot duplication resulting in the euAP1 and euFUL clades. Functional characterization of several euAP1 and euFUL genes has shown that both function in proper floral meristem identity, and axillary meristem repression. Independently, euAP1 genes function in floral meristem and sepal identity, whereas euFUL genes control phase transition, cauline leaf growth, compound leaf morphogenesis and fruit development. Significant functional variation has been detected in the function of pre-duplication basal-eudicot FUL-like genes, but the underlying mechanisms for change have not been identified. FUL-like genes in the Papaveraceae encode all functions reported for euAP1 and euFUL genes, whereas FUL-like genes in Aquilegia (Ranunculaceae function in inflorescence development and leaf complexity, but not in flower or fruit development. Here we isolated FUL-like genes across the Ranunculales and used phylogenetic approaches to analyze their evolutionary history. We identified an early duplication resulting in the RanFL1 and RanFL2 clades. RanFL1 genes were present in all the families sampled and are mostly under strong negative selection in the MADS, I and K domains. RanFL2 genes were only identified from Eupteleaceae, Papaveraceae s.l., Menispermaceae and Ranunculaceae and show relaxed purifying selection at the I and K domains. We discuss how asymmetric sequence diversification, new motifs, differences in codon substitutions and likely protein-protein interactions resulting from this Ranunculiid-specific duplication can help explain the functional differences among basal

  14. Conserved CDC20 cell cycle functions are carried out by two of the five isoforms in Arabidopsis thaliana.

    Directory of Open Access Journals (Sweden)

    Zoltán Kevei

    Full Text Available The CDC20 and Cdh1/CCS52 proteins are substrate determinants and activators of the Anaphase Promoting Complex/Cyclosome (APC/C E3 ubiquitin ligase and as such they control the mitotic cell cycle by targeting the degradation of various cell cycle regulators. In yeasts and animals the main CDC20 function is the destruction of securin and mitotic cyclins. Plants have multiple CDC20 gene copies whose functions have not been explored yet. In Arabidopsis thaliana there are five CDC20 isoforms and here we aimed at defining their contribution to cell cycle regulation, substrate selectivity and plant development.Studying the gene structure and phylogeny of plant CDC20s, the expression of the five AtCDC20 gene copies and their interactions with the APC/C subunit APC10, the CCS52 proteins, components of the mitotic checkpoint complex (MCC and mitotic cyclin substrates, conserved CDC20 functions could be assigned for AtCDC20.1 and AtCDC20.2. The other three intron-less genes were silent and specific for Arabidopsis. We show that AtCDC20.1 and AtCDC20.2 are components of the MCC and interact with mitotic cyclins with unexpected specificity. AtCDC20.1 and AtCDC20.2 are expressed in meristems, organ primordia and AtCDC20.1 also in pollen grains and developing seeds. Knocking down both genes simultaneously by RNAi resulted in severe delay in plant development and male sterility. In these lines, the meristem size was reduced while the cell size and ploidy levels were unaffected indicating that the lower cell number and likely slowdown of the cell cycle are the cause of reduced plant growth.The intron-containing CDC20 gene copies provide conserved and redundant functions for cell cycle progression in plants and are required for meristem maintenance, plant growth and male gametophyte formation. The Arabidopsis-specific intron-less genes are possibly "retrogenes" and have hitherto undefined functions or are pseudogenes.

  15. Expression patterns ofPassiflora edulis APETALA1/FRUITFULLhomologues shed light onto tendril and corona identities.

    Science.gov (United States)

    Scorza, Livia C T; Hernandes-Lopes, Jose; Melo-de-Pinna, Gladys F A; Dornelas, Marcelo C

    2017-01-01

    Passiflora (passionflowers) makes an excellent model for studying plant evolutionary development. They are mostly perennial climbers that display axillary tendrils, which are believed to be modifications of the inflorescence. Passionflowers are also recognized by their unique flower features, such as the extra whorls of floral organs composed of corona filaments and membranes enclosing the nectary. Although some work on Passiflora organ ontogeny has been done, the developmental identity of both Passiflora tendrils and the corona is still controversial. Here, we combined ultrastructural analysis and expression patterns of the flower meristem and floral organ identity genes of the MADS-box AP1 / FUL clade to reveal a possible role for these genes in the generation of evolutionary novelties in Passiflora . We followed the development of structures arising from the axillary meristem from juvenile to adult phase in P. edulis . We further assessed the expression pattern of P. edulis AP1 / FUL homologues ( PeAP1 and PeFUL ), by RT-qPCR and in situ hybridization in several tissues, correlating it with the developmental stages of P. edulis . PeAP1 is expressed only in the reproductive stage, and it is highly expressed in tendrils and in flower meristems from the onset of their development. PeAP1 is also expressed in sepals, petals and in corona filaments, suggesting a novel role for PeAP1 in floral organ diversification. PeFUL presented a broad expression pattern in both vegetative and reproductive tissues, and it is also expressed in fruits. Our results provide new molecular insights into the morphological diversity in the genus Passiflora . Here, we bring new evidence that tendrils are part of the Passiflora inflorescence. This points to the convergence of similar developmental processes involving the recruitment of genes related to flower identity in the origin of tendrils in different plant families. The data obtained also support the hypothesis that the corona

  16. Floral homeotic C function genes repress specific B function genes in the carpel whorl of the basal eudicot California poppy (Eschscholzia californica

    Directory of Open Access Journals (Sweden)

    Yellina Aravinda L

    2010-12-01

    Full Text Available Abstract Background The floral homeotic C function gene AGAMOUS (AG confers stamen and carpel identity and is involved in the regulation of floral meristem termination in Arabidopsis. Arabidopsis ag mutants show complete homeotic conversions of stamens into petals and carpels into sepals as well as indeterminacy of the floral meristem. Gene function analysis in model core eudicots and the monocots rice and maize suggest a conserved function for AG homologs in angiosperms. At the same time gene phylogenies reveal a complex history of gene duplications and repeated subfunctionalization of paralogs. Results EScaAG1 and EScaAG2, duplicate AG homologs in the basal eudicot Eschscholzia californica show a high degree of similarity in sequence and expression, although EScaAG2 expression is lower than EScaAG1 expression. Functional studies employing virus-induced gene silencing (VIGS demonstrate that knock down of EScaAG1 and 2 function leads to homeotic conversion of stamens into petaloid structures and defects in floral meristem termination. However, carpels are transformed into petaloid organs rather than sepaloid structures. We also show that a reduction of EScaAG1 and EScaAG2 expression leads to significantly increased expression of a subset of floral homeotic B genes. Conclusions This work presents expression and functional analysis of the two basal eudicot AG homologs. The reduction of EScaAG1 and 2 functions results in the change of stamen to petal identity and a transformation of the central whorl organ identity from carpel into petal identity. Petal identity requires the presence of the floral homeotic B function and our results show that the expression of a subset of B function genes extends into the central whorl when the C function is reduced. We propose a model for the evolution of B function regulation by C function suggesting that the mode of B function gene regulation found in Eschscholzia is ancestral and the C-independent regulation as

  17. Expression patterns of Passiflora edulis APETALA1/FRUITFULL homologues shed light onto tendril and corona identities

    Directory of Open Access Journals (Sweden)

    Livia C. T. Scorza

    2017-02-01

    Full Text Available Abstract Background Passiflora (passionflowers makes an excellent model for studying plant evolutionary development. They are mostly perennial climbers that display axillary tendrils, which are believed to be modifications of the inflorescence. Passionflowers are also recognized by their unique flower features, such as the extra whorls of floral organs composed of corona filaments and membranes enclosing the nectary. Although some work on Passiflora organ ontogeny has been done, the developmental identity of both Passiflora tendrils and the corona is still controversial. Here, we combined ultrastructural analysis and expression patterns of the flower meristem and floral organ identity genes of the MADS-box AP1/FUL clade to reveal a possible role for these genes in the generation of evolutionary novelties in Passiflora. Results We followed the development of structures arising from the axillary meristem from juvenile to adult phase in P. edulis. We further assessed the expression pattern of P. edulis AP1/FUL homologues (PeAP1 and PeFUL, by RT-qPCR and in situ hybridization in several tissues, correlating it with the developmental stages of P. edulis. PeAP1 is expressed only in the reproductive stage, and it is highly expressed in tendrils and in flower meristems from the onset of their development. PeAP1 is also expressed in sepals, petals and in corona filaments, suggesting a novel role for PeAP1 in floral organ diversification. PeFUL presented a broad expression pattern in both vegetative and reproductive tissues, and it is also expressed in fruits. Conclusions Our results provide new molecular insights into the morphological diversity in the genus Passiflora. Here, we bring new evidence that tendrils are part of the Passiflora inflorescence. This points to the convergence of similar developmental processes involving the recruitment of genes related to flower identity in the origin of tendrils in different plant families. The data obtained also

  18. The Garlic Allelochemical Diallyl Disulfide Affects Tomato Root Growth by Influencing Cell Division, Phytohormone Balance and Expansin Gene Expression.

    Science.gov (United States)

    Cheng, Fang; Cheng, Zhihui; Meng, Huanwen; Tang, Xiangwei

    2016-01-01

    Diallyl disulfide (DADS) is a volatile organosulfur compound derived from garlic (Allium sativum L.), and it is known as an allelochemical responsible for the strong allelopathic potential of garlic. The anticancer properties of DADS have been studied in experimental animals and various types of cancer cells, but to date, little is known about its mode of action as an allelochemical at the cytological level. The current research presents further studies on the effects of DADS on tomato (Solanum lycopersicum L.) seed germination, root growth, mitotic index, and cell size in root meristem, as well as the phytohormone levels and expression profile of auxin biosynthesis genes (FZYs), auxin transport genes (SlPINs), and expansin genes (EXPs) in tomato root. The results showed a biphasic, dose-dependent effect on tomato seed germination and root growth under different DADS concentrations. Lower concentrations (0.01-0.62 mM) of DADS significantly promoted root growth, whereas higher levels (6.20-20.67 mM) showed inhibitory effects. Cytological observations showed that the cell length of root meristem was increased and that the mitotic activity of meristematic cells in seedling root tips was enhanced at lower concentrations of DADS. In contrast, DADS at higher concentrations inhibited root growth by affecting both the length and division activity of meristematic cells. However, the cell width of the root meristem was not affected. Additionally, DADS increased the IAA and ZR contents of seedling roots in a dose-dependent manner. The influence on IAA content may be mediated by the up-regulation of FZYs and PINs. Further investigation into the underlying mechanism revealed that the expression levels of tomato EXPs were significantly affected by DADS. The expression levels of EXPB2 and beta-expansin precursor were increased after 3 d, and those of EXP1, EXPB3 and EXLB1 were increased after 5 d of DADS treatment (0.41 mM). This result suggests that tomato root growth may be

  19. In-vitro regeneration of castor bean (ricinus communis, L) and physic nut (jatropha curcas, L.)

    International Nuclear Information System (INIS)

    Afful, N. T.

    2008-06-01

    Investigations were conducted on in vitro regeneration of physic nut (Jatropha curcas, 1.) and castor bean (Ricinus communis, 1.) using zygotic embryo culture, shoot tip and meristem culture as well as somatic embryogenesis. Zygotic embryos from different stages of fruit maturity cultured on Murashige and Skoog (MS) medium supplemented with benzylaminopurine (BAP), kinetin and 2-isopentyl (2iP) produced vigorous seedlings with roots. However the optimal concentration of cytokinin for seedling development depended on the type cytokinin as well as the maturity stage of the fruit. Embryos from yellow fruits of Jatropha had the highest germination (100%) on an MS medium supplemented with 0.5 mg/L kinetin or 1 mg/L BAP while in Ricinus embryos from black fruits had the highest percentage germination (97%) on an MS medium modified with I mg/L 2iP or 0.5 or I mg/L BAP. Decrease in embryo viability especially in Jatropha as the seed matured may be due to high oil content in matured (black) fruit. Oil content in both Jatropha and Ricinus increased as the fruit matured from green to black and this may have effect on germination of zygotic embryos. In vitro culture response of shoot tip or meristem was significantly influenced by the concentration of growth regulators in the culture medium as well as the plant species. In both plant species, 2iP resulted in highest percentage shoot regeneration. The optimal concentration of 2iP was 0.5 mg/L for Ricinus shoot tip and 1.5 or 2.0 mg/L for Jatropha, indicating genotypic difference between the species. However excessive callus formation and browning in Ricinus led to the loss of all the regenerants. Shoot regeneration from meristem explants was also influenced by growth regulators with 2iP again being the best. Cultures of cotyledon and leaf lobe explants on MS medium supplemented with 2, 4-D and picloram resulted in callus induction with the exception of cotyledons obtained from black fruits. However transfer of calli onto fresh

  20. CLE peptides regulate lateral root development in response to nitrogen nutritional status of plants.

    Science.gov (United States)

    Araya, Takao; von Wirén, Nicolaus; Takahashi, Hideki

    2014-01-01

    CLE (CLAVATA3/embryo surrounding region (ESR)) peptides control meristem functions in plants. Our recent study highlights the critical role of a peptide-receptor signaling module composed of nitrogen (N)-responsive CLE peptides and the CLAVATA1 (CLV1) leucine-rich repeat receptor-like kinase in controlling lateral root development in Arabidopsis thaliana. CLE1, -3, -4 and -7 are expressed in root pericycle cells in Arabidopsis roots under N-limited growth conditions. Overexpression of these CLE genes inhibits lateral root emergence from the primary root. The inhibitory action of N-responsive CLE peptides on lateral root development requires the function of CLV1 expressed in phloem companion cells in roots, suggesting that downstream signals are transferred through phloem for systemic regulation of root system architecture. An additional mechanism downstream of CLV1 feedback-regulates transcript levels of N-responsive CLE genes in roots for fine-tuning the signal amplitude.

  1. MAIL1 is essential for development of the primary root but not of anchor roots.

    Science.gov (United States)

    Ühlken, Christine; Hoth, Stefan; Weingartner, Magdalena

    2014-01-01

    MAIN-LIKE1 (MAIL1) is a ubiquitously expressed nuclear protein, which has a crucial function during root development. We have recently described loss of function mutants for MAIL1, in which the organization and function of the primary root meristem is lost soon after germination. Moreover cell differentiation is impaired resulting in primary root growth arrest soon after emergence. Here we show that mail1 mutants form several anchor roots from the hypocotyl to root junction. These anchor roots show similar defects in the organization of the stem cell niche as the primary root. In contrast, differentiation processes are not impaired and thus anchor roots seem to be able to compensate for the loss of primary root function. Our data show that MAIL1 is essential for specification of cell fate in the primary root but not in anchor roots.

  2. Cytokinin signaling during root development.

    Science.gov (United States)

    Bishopp, Anthony; Help, Hanna; Helariutta, Ykä

    2009-01-01

    The cytokinin class of phytohormones regulates division and differentiation of plant cells. They are perceived and signaled by a phosphorelay mechanism similar to those observed in prokaryotes. Research into the components of phosphorelay had previously been marred by genetic redundancy. However, recent studies have addressed this with the creation of high-order mutants. In addition, several new elements regulating cytokinin signaling have been identified. This has uncovered many roles in diverse developmental and physiological processes. In this review, we look at these processes specifically in the context of root development. We focus on the formation and maintenance of the root apical meristem, primary and secondary vascular development, lateral root emergence and development, and root nodulation. We believe that the root is an ideal organ with which to investigate cytokinin signaling in a wider context.

  3. Root hydrotropism is controlled via a cortex-specific growth mechanism.

    Science.gov (United States)

    Dietrich, Daniela; Pang, Lei; Kobayashi, Akie; Fozard, John A; Boudolf, Véronique; Bhosale, Rahul; Antoni, Regina; Nguyen, Tuan; Hiratsuka, Sotaro; Fujii, Nobuharu; Miyazawa, Yutaka; Bae, Tae-Woong; Wells, Darren M; Owen, Markus R; Band, Leah R; Dyson, Rosemary J; Jensen, Oliver E; King, John R; Tracy, Saoirse R; Sturrock, Craig J; Mooney, Sacha J; Roberts, Jeremy A; Bhalerao, Rishikesh P; Dinneny, José R; Rodriguez, Pedro L; Nagatani, Akira; Hosokawa, Yoichiroh; Baskin, Tobias I; Pridmore, Tony P; De Veylder, Lieven; Takahashi, Hideyuki; Bennett, Malcolm J

    2017-05-08

    Plants can acclimate by using tropisms to link the direction of growth to environmental conditions. Hydrotropism allows roots to forage for water, a process known to depend on abscisic acid (ABA) but whose molecular and cellular basis remains unclear. Here we show that hydrotropism still occurs in roots after laser ablation removed the meristem and root cap. Additionally, targeted expression studies reveal that hydrotropism depends on the ABA signalling kinase SnRK2.2 and the hydrotropism-specific MIZ1, both acting specifically in elongation zone cortical cells. Conversely, hydrotropism, but not gravitropism, is inhibited by preventing differential cell-length increases in the cortex, but not in other cell types. We conclude that root tropic responses to gravity and water are driven by distinct tissue-based mechanisms. In addition, unlike its role in root gravitropism, the elongation zone performs a dual function during a hydrotropic response, both sensing a water potential gradient and subsequently undergoing differential growth.

  4. The influence of clinorotation on root cell differentiation in Brassica Rapa seedlings

    Science.gov (United States)

    Kalinina, Yana

    2005-08-01

    In this work we present the results of anatomical and ultrastructural investigations of root apices of Brassica rapa 6-day old seedlings grown in the stationary conditions and under slow horizontal clinorotation. The main attention was paid to the structural and functional organization of cells non-specialized for gravity perception during their growth and differentiation in a root. It was shown a decrease in length of the root growth zone due to reduction of the cell number in cell files under clinorotation. We conclude that the meristem proliferation activity was depressed under clinorotation. Some ultrastructural rearrangements of mitochondria in the distal elongation zone (DEZ) and increasing of their partial volume per cell were also observed. It is assumed that these changes reflect the intensification of mitochondrium functional activity in a DEZ cortex cells during clinorotation. An analysis of the experimental results supposes plants sense disorientation in the gravitational field as a stress.

  5. Transcriptional regulation of secondary growth and wood formation.

    Science.gov (United States)

    Du, Juan; Groover, Andrew

    2010-01-01

    Secondary growth and wood formation are products of the vascular cambium, a lateral meristem. Although the mechanisms have only recently begun to be uncovered, transcriptional regulation appears increasingly central to the regulation of secondary growth. The importance of transcriptional regulation is illustrated by the correlation of expression of specific classes of genes with related biological processes occurring at specific stages of secondary growth, including cell division, cell expansion, and cell differentiation. At the same time, transcription factors have been characterized that affect specific aspects of secondary growth, including regulation of the cambium and differentiation of cambial daughter cells. In the present review, we summarize evidence pointing to transcription as a major mechanism for regulation of secondary growth, and outline future approaches for comprehensively describing transcriptional networks underlying secondary growth.

  6. Citrus tissue culture employing vegetative explants.

    Science.gov (United States)

    Chaturvedi, H C; Singh, S K; Sharma, A K; Agnihotri, S

    2001-11-01

    Citrus being a number one fruit of the world due to its high nutritional value, huge production of fruits and fruit products, the citrus industry may be considered a major fruit industry. Though citrus orchard area in India is comparable to USA, the produce is far less, while its export is nil. Biotechnology has played an outstanding role in boosting the citrus industry, e.g., in Spain, which is now the biggest exporter of citrus fruit with the application of micrografting. Amongst the fruit trees, perhaps the maximum tissue culture research has been done in citrus during the past four decades, however, the results of practical value are meagre. The shortfalls in citrus tissue culture research and some advancements made in this direction along with bright prospects are highlighted, restricting the review to vegetative explants only. Whilst utilization of nucellar embryogenesis is limited to rootstocks, the other aspects, like, regeneration and proliferation of shoot meristems measuring 200 microm in length--a global breakthrough--of two commercially important scion species, Citrus aurantifolia and C. sinensis and an important rootstock, C. limonia, improvement of micrografting technique, cloning of the same two scion species as well as some Indian rootstock species, employing nodal stem segments of mature trees, of immense practical value have been elaborated. A rare phenomenon of shift in the morphogenetic pattern of differentiation from shoot bud differentiation to embryoid formation occurred during the long-term culture of stem callus of C. grandis. Stem callus-regenerated plants of C. aurantifolia, C. sinensis and C. grandis showed variation in their ploidy levels and a somaclonal variant of C. sinensis, which produced seedless fruits was isolated. Tailoring of rooting in microshoots to a tap root-like system by changing the inorganic salt composition of the rooting medium, resulting in 100% transplant success, and germplasm preservation through normal growth

  7. Radiation doses and possible radiation effects of low-level, chronic radiation in vegetation

    International Nuclear Information System (INIS)

    Rhoads, W.A.; Franks, L.A.

    1975-01-01

    Measurements were made of radiation doses in soil and vegetation in Pu-contaminated areas at the Nevada Test Site with the objective of investigating low-level, low-energy gamma radiation (with some beta radiation) effects at the cytological or morphological level in native shrubs. In this preliminary investigation, the exposure doses to shrubs at the approximate height of stem apical meristems were estimated from 35 to 140 R for a ten-year period. The gamma exposure dose estimated for the same period was 20.7 percent +- 6.4 percent of that recorded by the dosimeters used in several kinds of field instrument surveys. Hence, a survey instrument reading made at about 25 cm in the tops of shrubs should indicate about 1 / 5 the dosimeter-measured exposures. No cytology has yet been undertaken because of the drought since last winter. (auth)

  8. Transient expression of green fluorescent protein in parasitic dodder as a tool for studying of cytoskeleton

    Directory of Open Access Journals (Sweden)

    Kaštier Peter

    2017-06-01

    Full Text Available Dodder (Cuscuta species cause severe agricultural damage in many countries throughout the world. To establish strategies for control of its growth and spreading it is important to study its life cycle and survival strategies. For these efforts genetic modification would represent a powerful tool. Here we report on Agrobacteriummediated transformation of dodder using green fluorescent protein (GFP fused to actin-binding protein as a vital marker. Since the shoot of germinating C. europaea contains a functional apical meristem and grows quickly comparing to the root-like structure, the shoot apex was used here as explant. The transgene expression was only transient, nevertheless it enabled to detect allocation of actin filaments and studying the cytoskeleton organization in dodder shoot apex. Transient expression of GFP appears to be a suitable method for studying Cuscuta development through cytoskeleton organisation that is presently largely unexplored.

  9. A mechanically sensitive cell layer regulates the physical properties of the Arabidopsis seed coat.

    Science.gov (United States)

    Creff, Audrey; Brocard, Lysiane; Ingram, Gwyneth

    2015-02-23

    Endogenous mechanical stresses regulate plant growth and development. Tensile stress in epidermal cells affects microtubule reorientation and anisotropic cell wall deposition, and mechanical stimulus at the meristem regulates trafficking and polar localization of auxin transporters. However, the mechanical regulation of other plant growth regulators has not been demonstrated. Here we propose that during seed growth, mechanical stress exerted by the expanding embryo and endosperm is perceived by a specific mechanosensitive cell layer in the seed coat. We show that the adaxial epidermis of the outer integument thickens its cell wall in a mechanosensitive fashion, demonstrates microtubule dynamics consistent with mechanical stress perception and shows mechanosensitive expression of ELA1, a regulator of seed size and gibberellic acid (GA) metabolism. By exploiting physical and genetic compartmentalization, and combining genetic and surgical techniques, we propose a mechanistic link between mechanical stress and GA accumulation that regulates seed development.

  10. Development and characterization of microsatellite markers for Central American Begonia sect. Gireoudia (Begoniaceae).

    Science.gov (United States)

    Twyford, Alex D; Ennos, Richard A; Kidner, Catherine A

    2013-05-01

    Transcriptome sequence data were used to design microsatellite primers for two widespread Central American Begonia species, B. heracleifolia and B. nelumbiifolia, to investigate population structure and hybridization. • The transcriptome from vegetative meristem tissue from the related B. plebeja was mined for microsatellite loci, and 31 primer pairs amplified in the target species. Fifteen primer pairs were combined in two multiplex PCR reactions, which amplified an average of four alleles per locus. • The markers developed will be a valuable genetic resource for medium-throughput genotyping of Central American species of Begonia sect. Gireoudia. A subset of these markers have perfect sequence matches to Asian B. venusta, and are promising for studies in other Begonia sections.

  11. Phenotype-gene: 82 [Arabidopsis Phenome Database[Archive

    Lifescience Database Archive (English)

    Full Text Available 82 http://metadb.riken.jp/db/SciNetS_ria224i/cria224u3ria224u1081i decreased efficien...cy in organ named portion of meristem tissue during process named cell division for AT5G40770 Van Aken Ol...ivier et al. 2007 Dec. Plant J. 52(5):850-64. http://metadb.riken.jp/db/SciNetS_ria224i/cria224u4ria224u17883375i decreased efficien...ss named cell division http://metadb.riken.jp/db/SciNetS_ria224i/cria224u1ria224u656i AT5G40770

  12. Nondestructive water imaging by neutron beam analysis in living plants

    International Nuclear Information System (INIS)

    Nakanishi, T.M.; Matsubayashi, M.

    1997-01-01

    Analysis of biological activity in intact cells or tissues is essential to understand many life processes. Techniques for these in vivo measurements have not been well developed. We present here a nondestructive method to image water in living plants using a neutron beam. This technique provides the highest resolution for water in tissue yet obtainable. With high specificity to water, this neutron beam technique images water movement in seeds or in roots imbedded in soil, as well as in wood and meristems during development. The resolution of the image attainable now is about 15 μm. We also describe how this new technique will allow new investigations in the field of plant research. (author)

  13. Expression and Maintenance of Embryogenic Potential Is Enhanced through Constitutive Expression of AGAMOUS-Like 151

    Science.gov (United States)

    Harding, Ellen W.; Tang, Weining; Nichols, Karl W.; Fernandez, Donna E.; Perry, Sharyn E.

    2003-01-01

    The MADS domain protein AGL15 (AGAMOUS-Like 15) has been found to preferentially accumulate in angiosperm tissues derived from double fertilization (i.e. the embryo, suspensor, and endosperm) and in apomictic, somatic, and microspore embryos. Localization to the nuclei supports a role in gene regulation during this phase of the life cycle. To test whether AGL15 is involved in the promotion and maintenance of embryo identity, the embryogenic potential of transgenic plants that constitutively express AGL15 was assessed. Expression of AGL15 was found to enhance production of secondary embryos from cultured zygotic embryos, and constitutive expression led to long-term maintenance of development in this mode. Ectopic accumulation of AGL15 also promoted somatic embryo formation after germination from the shoot apical meristem of seedlings in culture. These results indicate that AGL15 is involved in support of development in an embryonic mode. PMID:14512519

  14. Use of radiation for inducing mutants in potatoes through tissue culture technique

    International Nuclear Information System (INIS)

    Sharabash, M.T.

    1997-01-01

    Meristem-tips obtained from sprouts of potato tubers, cv. 'Diamant' (Solanum tuberosum) were cultured on MS-medium and multiplied into plantlets through micropropagation. After 2-3 weeks, the micropropagated plantlets had 5-6 nodes each. The plantlets were irradiated with 20 to 40 Gy gamma rays at 27.7 rad/sec. Irradiated plantlets were cut into single nodes and cultured on MS-medium supplemented with 2 g NaCl. Salt resistant plantlets were transferred to MS-liquid medium supplemented with 2g NaCl/l 5.2, and microtubers were collected after 6 weeks. Minitubers were produced under the same level of salinity. (author). 2 tabs

  15. Building A NGS Genomic Resource: Towards Molecular Breeding In L. Perenne

    DEFF Research Database (Denmark)

    Ruttink, Tom; Roldán-Ruiz, Isabel; Asp, Torben

    of SNP markers in selected candidate genes. In parallel, a germplasm collection of 602 Lolium genotypes was established and is being phenotyped for plant architecture, reproductive characteristics, flowering time, and forage quality traits. We will test through association genetics whether phenotypic......To advance the application of molecular breeding in Lolium perenne, we have generated a sequence resource to facilitate gene discovery and SNP marker development. Illumina GAII transcriptome sequencing was performed on meristem-enriched samples of 14 Lolium genotypes. De novo assemblies...... for individual genotypes was carried out with 12-30M paired-end reads per genotype using the CLCBio Genomics Workbench, yielding around 70,000 contigs per genotype. 54% of these contigs have a significant BLAST hit with a predicted Brachypodium gene. Vice versa, for around 60% of the 26,552 predicted...

  16. Extracellular matrix surface network is associated with non-morphogenic calli of Helianthus tuberosus cv. Albik produced from various explants

    Directory of Open Access Journals (Sweden)

    Maria Pilarska

    2014-03-01

    Full Text Available Helianthus tuberosus is economically important species. To improve characters of this energetic plant via genetic modification, production of callus tissue and plant regeneration are the first steps. A new, potentially energetic cultivar Albik was used in this study to test callus induction and regeneration. Callus was produced on leaves, petioles, apical meristems and stems from field-harvested plants but was totally non-morphogenic. Its induction started in the cortex and vascular bundles as confirmed by histological analysis. The surface of heterogeneous callus was partially covered with a membranous extracellular matrix surface network visible in scanning and transmission electron microscopies. The results clearly indicate that: (i the morphogenic capacity of callus in topinambur is genotype dependent, (ii cv. Albik of H. tuberosus proved recalcitrant in in vitro regeneration, and (iii extracellular matrix surface network is not a morphogenic marker in this cultivar.

  17. Histology of somatic embryos of eurycoma longifolia (simaroubaceae): relevance in agrobacterium rhizogenes-mediated transformation

    International Nuclear Information System (INIS)

    Balakrishnan, B.; Rabiah, S.S.; Keng, C.L.

    2014-01-01

    Histological analysis conducted on somatic embryos of Eurycoma longifolia shows the developmental structures that are remarkably similar to seeds found in the wild. The primary components of a growing somatic embryo are its shoot and root apical meristems indicated by dense layers of rapidly growing cells. The increased understanding of In vitro culture systems and anatomical changes provide information into cellular processes that govern genetic transformation of E. longifolia with Agrobacterium rhizogenes. The presence of meristematic regions on cultured somatic embryos suggests that they are suitable for genetic transformation as genetic elements could be transported to these regions where growth and differentiation are centered. This allows the successful integration and expression of transferred DNA in the host organism, leading the way for an efficient A. rhizogenes-mediated transformation protocol. (author)

  18. Flower development: open questions and future directions.

    Science.gov (United States)

    Wellmer, Frank; Bowman, John L; Davies, Brendan; Ferrándiz, Cristina; Fletcher, Jennifer C; Franks, Robert G; Graciet, Emmanuelle; Gregis, Veronica; Ito, Toshiro; Jack, Thomas P; Jiao, Yuling; Kater, Martin M; Ma, Hong; Meyerowitz, Elliot M; Prunet, Nathanaël; Riechmann, José Luis

    2014-01-01

    Almost three decades of genetic and molecular analyses have resulted in detailed insights into many of the processes that take place during flower development and in the identification of a large number of key regulatory genes that control these processes. Despite this impressive progress, many questions about how flower development is controlled in different angiosperm species remain unanswered. In this chapter, we discuss some of these open questions and the experimental strategies with which they could be addressed. Specifically, we focus on the areas of floral meristem development and patterning, floral organ specification and differentiation, as well as on the molecular mechanisms underlying the evolutionary changes that have led to the astounding variations in flower size and architecture among extant and extinct angiosperms.

  19. Apple latent spherical virus vectors for reliable and effective virus-induced gene silencing among a broad range of plants including tobacco, tomato, Arabidopsis thaliana, cucurbits, and legumes

    International Nuclear Information System (INIS)

    Igarashi, Aki; Yamagata, Kousuke; Sugai, Tomokazu; Takahashi, Yukari; Sugawara, Emiko; Tamura, Akihiro; Yaegashi, Hajime; Yamagishi, Noriko; Takahashi, Tsubasa; Isogai, Masamichi; Takahashi, Hideki; Yoshikawa, Nobuyuki

    2009-01-01

    Apple latent spherical virus (ALSV) vectors were evaluated for virus-induced gene silencing (VIGS) of endogenous genes among a broad range of plant species. ALSV vectors carrying partial sequences of a subunit of magnesium chelatase (SU) and phytoene desaturase (PDS) genes induced highly uniform knockout phenotypes typical of SU and PDS inhibition on model plants such as tobacco and Arabidopsis thaliana, and economically important crops such as tomato, legume, and cucurbit species. The silencing phenotypes persisted throughout plant growth in these plants. In addition, ALSV vectors could be successfully used to silence a meristem gene, proliferating cell nuclear antigen and disease resistant N gene in tobacco and RCY1 gene in A. thaliana. As ALSV infects most host plants symptomlessly and effectively induces stable VIGS for long periods, the ALSV vector is a valuable tool to determine the functions of interested genes among a broad range of plant species.

  20. GOLVEN secretory peptides regulate auxin carrier turnover during plant gravitropic responses.

    Science.gov (United States)

    Whitford, Ryan; Fernandez, Ana; Tejos, Ricardo; Pérez, Amparo Cuéllar; Kleine-Vehn, Jürgen; Vanneste, Steffen; Drozdzecki, Andrzej; Leitner, Johannes; Abas, Lindy; Aerts, Maarten; Hoogewijs, Kurt; Baster, Pawel; De Groodt, Ruth; Lin, Yao-Cheng; Storme, Véronique; Van de Peer, Yves; Beeckman, Tom; Madder, Annemieke; Devreese, Bart; Luschnig, Christian; Friml, Jiří; Hilson, Pierre

    2012-03-13

    Growth and development are coordinated by an array of intercellular communications. Known plant signaling molecules include phytohormones and hormone peptides. Although both classes can be implicated in the same developmental processes, little is known about the interplay between phytohormone action and peptide signaling within the cellular microenvironment. We show that genes coding for small secretory peptides, designated GOLVEN (GLV), modulate the distribution of the phytohormone auxin. The deregulation of the GLV function impairs the formation of auxin gradients and alters the reorientation of shoots and roots after a gravity stimulus. Specifically, the GLV signal modulates the trafficking dynamics of the auxin efflux carrier PIN-FORMED2 involved in root tropic responses and meristem organization. Our work links the local action of secretory peptides with phytohormone transport. Copyright © 2012 Elsevier Inc. All rights reserved.

  1. Cassava (Manihot esculenta Crantz).

    Science.gov (United States)

    Bull, Simon E

    2015-01-01

    Genetic transformation of plants is an indispensable technique used for fundamental research and crop improvement. Recent advances in cassava (Manihot esculenta Crantz) transformation have facilitated the effective generation of stably transformed cassava plants with favorable traits. Agrobacterium-mediated transformation of friable, embryogenic callus has evolved to become the most widely used approach and has been adopted by research laboratories in Africa. This procedure utilizes axillary meristem tissue (buds) to produce primary and secondary somatic embryos and subsequently friable, embryogenic callus. Agrobacterium harboring a binary expression cassette is used to transform this tissue, which is regenerated via cotyledons and shoot organogenesis to produce rooted in vitro plantlets. This chapter details each step of the procedure using the model cultivar 60444 and provides supplementary notes to successfully produce transgenic cassava.

  2. Molecular basis of development in petaloid monocot flowers

    DEFF Research Database (Denmark)

    Johansen, Bo; Frederiksen, Signe; Skipper, Martin

    2006-01-01

    The molecular background of flower development has been intensively studied within core eudicots, and several studies have confirmed the extended ABC model as the molecular background of flower development in this plant group. The core eudicots are characterized as having one copy of each of the B......-class genes apparently are expressed in meristems of both flower and inflorescence. Morphologically petaloid stamens and styles are well known within the petaloid monocots, whereas the phenomenon is rare in core eudicots. A simple model based on the extra copies of B-class genes can explain the molecular...... that A- and C-class gene expression is not mutually exclusive in monocots. The difference in expression of the A-class genes outside the floral organs shows a fundamental difference between monocot and core eudicot flowers....

  3. Automated Tracking of Root for Confocal Time-lapse Imaging of Cellular Processes.

    Science.gov (United States)

    Doumane, Mehdi; Lionnet, Claire; Bayle, Vincent; Jaillais, Yvon; Caillaud, Marie-Cécile

    2017-04-20

    Here we describe a protocol that enables to automatically perform time-lapse imaging of growing root tips for several hours. Plants roots expressing fluorescent proteins or stained with dyes are imaged while they grow using automatic movement of the microscope stage that compensates for root growth and allows to follow a given region of the root over time. The protocol makes possible the image acquisition of multiple growing root tips, therefore increasing the number of recorded mitotic events in a given experiment. The protocol also allows the visualization of more than one fluorescent protein or dye simultaneously, using multiple channel acquisition. We particularly focus on imaging of cytokinesis in Arabidopsis root tip meristem, but this protocol is also suitable to follow root hair growth, pollen tube growth, and other regions of root over time, in various plant species. It may as well be amendable to automatically track non-plant structures with an apical growth.

  4. Biological and chemical investigation of Allium cepa L. response to selenium inorganic compounds.

    Science.gov (United States)

    Michalska-Kacymirow, M; Kurek, E; Smolis, A; Wierzbicka, M; Bulska, E

    2014-06-01

    The aim of this study was to evaluate the biological and chemical response of Allium cepa L. exposed to inorganic selenium compounds. Besides the investigation of the total content of selenium as well as its chemical speciation, the Allium test was used to evaluate the growth of onion roots and mitotic activity in the roots' meristem. The total content of selenium was determined by inductively coupled plasma mass spectrometry (ICP MS). High-performance liquid chromatography (HPLC), coupled to ICP MS, was used for the selenium chemical speciation. Results indicated that A. cepa plants are able to biotransform inorganic selenium compounds into their organic derivatives, e.g., Se-methylselenocysteine from the Se(IV) inorganic precursor. Although the differences in the biotransformation of selenium are due mainly to the oxidation state of selenium, the experiment has also shown a fine effect of counter ions (H(+), Na(+), NH4 (+)) on the response of plants and on the specific metabolism of selenium.

  5. Katanin: A Sword Cutting Microtubules for Cellular, Developmental, and Physiological Purposes

    Directory of Open Access Journals (Sweden)

    Ivan Luptovčiak

    2017-11-01

    Full Text Available KATANIN is a well-studied microtubule severing protein affecting microtubule organization and dynamic properties in higher plants. By regulating mitotic and cytokinetic and cortical microtubule arrays it is involved in the progression of cell division and cell division plane orientation. KATANIN is also involved in cell elongation and morphogenesis during plant growth. In this way KATANIN plays critical roles in diverse plant developmental processes including the development of pollen, embryo, seed, meristem, root, hypocotyl, cotyledon, leaf, shoot, and silique. KATANIN-dependent microtubule regulation seems to be under the control of plant hormones. This minireview provides an overview on available KATANIN mutants and discusses advances in our understanding of KATANIN biological roles in plants.

  6. Mutagenesis for ACMV resistance in a Ghanian cassava cultivar 'Bosom nsia'

    International Nuclear Information System (INIS)

    Ahiabu, R.K.; Lokko, Y.; Danso, K.; Klu, G.Y.P.

    1997-01-01

    Breeding for resistance to the African Cassava Mosaic Virus (ACMV) disease in the Ghanian cassava cultivar 'Bosom nsia' has been on-going for the past four years at the Biotechnology and Nuclear Agricultural Research Institute. Protocols for in vitro culture from shoot meristems and acclimation of plantlets were established. Radiosensitivity tests on the regenerated plantlets indicated LD 50 of 40 Gy, and doses of 25, 30 and 35 Gy were suitable for mutagenesis. These doses were applied to in vivo and in vitro grown plants, and selection was carried out in three propagations. Four variants, selected under field conditions with high viral incidence, were analyzed for virus particles with three virus indexing techniques. Polymerase chain reaction (PCR) product analysis of DNA extracts from Nicotiana benthamiana test plants, inoculated with sap from the leaves of variants, confirmed the presence of virus particles in all variants. Inoculation and ELISA tests suggested ACMV tolerance in selected variants. (author). 24 refs, 3 figs, 1 tab

  7. [Assessment of cyto- and genotoxicity of natural waters in the vicinity of radioactive waste storage facility using Allium-test].

    Science.gov (United States)

    Udalova, A A; Geras'kin, S A; Dikarev, V G; Dikareva, N S

    2014-01-01

    Efficacy of bioassays of "aberrant cells frequency" and "proliferative activity" in root meristem of Allium cepa L. is studied in the present work for a cyto- and genotoxicity assessment of natural waters contaminated with 90Sr and heavy metals in the vicinity of the radioactive waste storage facility in Obninsk, Kaluga region. The Allium-test is shown to be applicable for the diagnostics of environmental media at their combined pollution with chemical and radioactive substances. The analysis of aberration spectrum shows an important role of chemical toxicants in the mutagenic potential of waters collected in the vicinity of the radioactive waste storage facility. Biological effects are not always possible to explain from the knowledge on water contamination levels, which shows limitations of physical-chemical monitoring in providing the adequate risk assessment for human and biota from multicomponent environmental impacts.

  8. Emerging concepts in chromatin-level regulation of plant cell differentiation: timing, counting, sensing and maintaining.

    Science.gov (United States)

    Morao, Ana Karina; Bouyer, Daniel; Roudier, François

    2016-12-01

    Plants are characterized by a remarkable phenotypic plasticity that meets the constraints of a sessile lifestyle and the need to adjust constantly to the environment. Recent studies have begun to reveal how chromatin dynamics participate in coordinating cell proliferation and differentiation in response to developmental cues as well as environmental fluctuations. In this review, we discuss the pivotal function of chromatin-based mechanisms in cell fate acquisition and maintenance, within as well as outside meristems. In particular, we highlight the emerging role of specific epigenomic factors and chromatin pathways in timing the activity of stem cells, counting cell divisions and positioning cell fate transitions by sensing phytohormone gradients. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Push-pull strategy in the regulation of postembryonic root development.

    Science.gov (United States)

    Choe, Goh; Lee, Ji-Young

    2017-02-01

    Unlike animals, plants continue to grow throughout their lives. The stem cell niche, protected in meristems of shoots and roots, enables this process. In the root, stem cells produce precursors for highly organized cell types via asymmetric cell divisions. These precursors, which are "transit-amplifying cells," actively divide for several rounds before entering into differentiation programs. In this review, we highlight positive feedback regulation between shoot- and root-ward signals during the postembryonic root growth, which is reminiscent of a "push-pull strategy" in business parlance. This property of molecular networks underlies the regulation of stem cells and their organizer, the "quiescent center," as well as of the signaling between stem cell niche, transit-amplifying cells, and beyond. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Banana research in the FAO/IAEA agriculture and biotechnology laboratory

    International Nuclear Information System (INIS)

    Morpurgo, R.; Afza, R.; Brunner, H.; Roux, N.; Grasso, G.; Lee, K.S.; Duren, M. Van; Zapata-Arias, F.J.

    1997-01-01

    The primary activity of the Agriculture and Biotechnology Laboratory on banana has been to develop and transfer mutation techniques using nuclear and related biotechnology, provide training and mutagen treatment services and technical advice to the Member States. The complex genetic nature and lack of seed formation do not allow conventional breeding of Musa varieties. The FAO/IAEA laboratory has developed in vitro techniques to induce mutations, minimize chimerisms, and rapid propagation of banana. The most commonly used method of propagation is rapid proliferation of axillary and adventitious buds from meristem tip culture. Somatic embryogenesis has been induced in clones with different genomic constitution; however, the low germination rate of somatic embryos is still a major constraint. Investigations have been carried out on enzymes associated with resistance to Fusarium oxisporum f. sp. cubense. Molecular methods based on DNA oligonucleotide and DNA amplification fingerprinting are being developed for genomic characterization of species, cultivars and mutant clones. (author)

  11. Role of rice PPS in late vegetative and reproductive growth.

    Science.gov (United States)

    Tanaka, Nobuhiro; Itoh, Jun-Ichi; Nagato, Yasuo

    2012-01-01

    The rice peter pan syndrome-1 (pps-1) mutant shows a prolonged juvenile phase and early flowering. Although the early vegetative phase and flowering time of pps-1 have been closely examined, the phenotypes in the late vegetative and reproductive phases are not yet well understood. In the ninth leaf blade of pps-1, the relative length of the midrib was comparable to the sixth leaf blade of wild-type. Moreover, pps-1 had a small inflorescence meristem and small panicles. These phenotypes indicate that in pps-1 the juvenile phase coexists with the late vegetative phase, resulting in small panicles. Gibberellin is known to promote the juvenile-adult phase transition. d18-k is dwarf and has a prolonged juvenile phase. Double mutant (d18-k pps-1) showed the same phenotype as the pps-1, indicating that PPS is upstream of GA biosynthetic genes.

  12. Morphology and anatomy of developing fruits and seeds of Vismia guianensis (Aubl.) Choisy (Clusiaceae).

    Science.gov (United States)

    Mourão, K S; Beltrati, C M

    2001-02-01

    Morphological, structural and developmental features of fruits and seeds of Vismia guianensis (Aubl.) Choisy. are here presented, with the purpose to elucidate their structure and to contribute to taxonomical and ecological studies of the family. The fruit is a berry and the "rind" is constituted by the exocarp and by the subepidermal layers which constitute the mesocarp. The reddish pulp, rich in starch, is constituted by the parenchymatic mesocarp, with branched secretory ducts and vascular bundles, joined with the endocarp, which arises from a ventral meristem. The bitegmic, anatropous ovules, provided by the endothelium, develop into anatropous, bitegmic and exalbuminous seeds. The reddish uniseriate testa shows phenolic contents. The tegmen becomes crushed resting only the uniseriate exotegmen with undulate, thick walled and lignified cells, which contain a number of calcium oxalate prismatic crystals. The embryo, rich in lipids, is straight and shows foliaceous cotyledons.

  13. Morphology and anatomy of the developing fruit and seed of Dalechampia stipulacea Müll. Arg. (Euphorbiaceae - DOI: 10.4025/actascibiolsci.v31i4.4834

    Directory of Open Access Journals (Sweden)

    Luiz Antonio de Souza

    2009-08-01

    Full Text Available In forest remnants of Maringá, Paraná, Brazil, there is abundance of the liana species, with little studied reproductive structures, morphologically and anatomically. Among these species occurs Dalechampia stipulacea Müll. Arg., which is the object of the present study. It is a Euphorbiaceae with pseudanthium and trichomes that cause irritation of the skin. The fruits and seeds were fixed and cut freehand and in a rotation microtome, according to the usual techniques. The fruit is a schizocarp tricocca with loculicidal and septicidal dehiscence. The mature pericarp presents sclerenchymatous middle mesocarp and endocarp that originate from meristems installed in the ovary mesophyll and epidermis. The inner mesocarp is constituted by a layer of macrosclereids of subepidermic origin. The seed originates from anatropous, bitegmic and crassinucelate ovule; it is exotegmic and albuminous. The seed presents structural characteristics verified in Acalyphoideae, except for the mesotegmen vascularization

  14. The stability of induced compact mutant clones of Bramley's Seedling apple

    International Nuclear Information System (INIS)

    Lacey, C.N.D.

    1982-01-01

    Twelve selected, compact, clones of Bramley's Seedling induced by gamma radiation treatment were checked for stability. Representative trees were used as vegetative parents for large scale multiplication, and further buds were treated with gamma radiation to disrupt the structure of their meristems. The results indicate that seven of the clones are as stable as the original cultivar, and therefore probably homohistont, containing only cells with compact mutant genotype. The other five clones proved to be unstable and gave rise to a large proportion of apparently normal trees. It is hypothesized that in these clones the L 1 (epidermis) consists of normal unchanged tissue, while the bulk of the plant tissue layers are of mutant cells, i.e. that they are periclinal chimaeras with the genotypes of the different cell layers coded for different growth forms. (orig.)

  15. Virus Elimination from Ornamental Plants Using in vitro Culture Techniques

    Directory of Open Access Journals (Sweden)

    Snežana Milošević

    2012-01-01

    Full Text Available Viruses are responsible for numerous epidemics in different crops in all parts of the world.As a consequence of their presence great economic losses are being incurred. In addition tothe development of sensitive techniques for detection, identification and characterization ofviruses, substantial attention has also been paid to biotechnological methods for their eliminationfrom plants. In this review article, the following biotechnological in vitro culture techniquesfor virus elimination from ornamental plants are presented: meristem culture, thermotherapy,chemotherapy, cryotherapy or a combination of these methods. The plant species,as well as the type of virus determine the choice of a most suitable method. The state ofthe art in investigation of virus elimination from Impatiens sp. in Serbia is summarized.

  16. Induction of micronuclei by irradiation with neutrons produced from 600 MeV protons

    CERN Document Server

    Diehl-Marshall, I

    1980-01-01

    Chromosome damage can be detected by the observation of micronuclei . Because its sensitivity, the micronuclei induciton in meristems of Vicia faba bean roots has been selected to determine the radiation damage produced by doses ranging from 1 to 82 cGy of neutrons. The average number of miconuclei found between 24 and 48 hours after irradiation was plotted as a funciton of dose. The RBE values, using as reference radiation 60 Co y-rays, ranged from 3.5 for a neutron dose of 82 cGy to 18 for a neutron of 1 cGy. Even higher RBE values were deduced at low doses from the evaluation of cells containing multiple micronuclei.

  17. Multiple shoot cultures of Atropa belladonna: Effect of physico-chemical factors on growth and alkaloid formation

    International Nuclear Information System (INIS)

    Benjamin, B.D.; Roja, P.C.; Heble, M.R.; Chandha, M.S.

    1987-01-01

    Multiple shoot cultures were established from shoot tip and axillary meristem of the plant Atropa belladonna. The cultures were initially raised on agar medium and subsequently maintained on liquid medium of Murashige and Skoog (1962) supplemented with BA. These cultures were subjected to different doses of -y-irradiation. Recovery from the radiation effects was observed in tissues subjected to 29 Gy during four successive passages. Plant growth regulators influenced the growth and morphogenetic events of the tissues. The precursors of tropane alkaloids marginally increased the alkaloid synthesis during the stationary phase of growth. Shoot cultures, established from different field grown plants varying in alkaloid content, were morphologically similar and did not exhibit the parental characteristics with respect to alkaloid formation

  18. The Effect of Laser Treatment as a Weed Control Method

    DEFF Research Database (Denmark)

    Bak, Thomas; Mathiassen, Solvejg K.; Christensen, Svend

    2006-01-01

    was related to wavelength, exposure time, spot size and laser power. The efficacy also varied between the weed species. The results indicate that the efficacy of laser treatments can be improved by a more precise pointing of the laser beam towards the apical meristems and optimisation of the energy density......A laser beam directed towards weeds can be an efficient weed control method as an alternative to herbicides. Lasers may deliver high-density energy to selected plant material, raising the temperature of the water in the plant cells and thereby stop or delay the growth. A commercial use of lasers...... (exposure time and spot size of the laser beam). The experiment also showed a significant difference between two wavelengths. In order to improve the performance and to validate the efficacy on a broader spectrum of weed species, further research and development is needed....

  19. Plant stem cell niches.

    Science.gov (United States)

    Aichinger, Ernst; Kornet, Noortje; Friedrich, Thomas; Laux, Thomas

    2012-01-01

    Multicellular organisms possess pluripotent stem cells to form new organs, replenish the daily loss of cells, or regenerate organs after injury. Stem cells are maintained in specific environments, the stem cell niches, that provide signals to block differentiation. In plants, stem cell niches are situated in the shoot, root, and vascular meristems-self-perpetuating units of organ formation. Plants' lifelong activity-which, as in the case of trees, can extend over more than a thousand years-requires that a robust regulatory network keep the balance between pluripotent stem cells and differentiating descendants. In this review, we focus on current models in plant stem cell research elaborated during the past two decades, mainly in the model plant Arabidopsis thaliana. We address the roles of mobile signals on transcriptional modules involved in balancing cell fates. In addition, we discuss shared features of and differences between the distinct stem cell niches of Arabidopsis.

  20. Ascorbate oxidase is the potential conductor of a symphony of signaling pathways.

    Science.gov (United States)

    De Tullio, Mario C; Guether, Mike; Balestrini, Raffaella

    2013-03-01

    The functional role of ascorbate oxidase (AO; EC 1.10.3.3) has never been fully explained so far, due to the difficulties in understanding the presence of an enzyme specifically oxidizing ascorbate with no obvious advantage, and the apparent disadvantage of lowering plant stress resistance as a consequence of ascorbate consumption. Here we suggest a complete change of perspective, by proposing an essential role of AO as a modulator of both ascorbate and oxygen content, with relevant implications related to signaling. By affecting the overall redox state, AO is actually involved in redox regulation in the extracellular matrix. In addition, AO can contribute to creating a hypoxic microenvironment, especially relevant in the maintenance of meristem identity and the establishment of mutualistic plant-microbe interactions. We also hypothesize the possible involvement of AO in the activation of a signaling cascade analogous to the mechanism of prolyl hydroxylases/Hypoxia Inducible Factors in animals.