Rodriguez-Saona, Cesar; Parra, Leonardo; Quiroz, Andrés; Isaacs, Rufus
Studies of the effects of pollination on floral scent and bee visitation remain rare, particularly in agricultural crops. To fill this gap, the hypothesis that bee visitation to flowers decreases after pollination through reduced floral volatile emissions in highbush blueberries, Vaccinium corymbosum, was tested. Other sources of variation in floral emissions and the role of floral volatiles in bee attraction were also examined. Pollinator visitation to blueberry flowers was manipulated by bagging all flowers within a bush (pollinator excluded) or leaving them unbagged (open pollinated), and then the effect on floral volatile emissions and future bee visitation were measured. Floral volatiles were also measured from different blueberry cultivars, times of the day and flower parts, and a study was conducted to test the attraction of bees to floral volatiles. Open-pollinated blueberry flowers had 32 % lower volatile emissions than pollinator-excluded flowers. In particular, cinnamyl alcohol, a major component of the floral blend that is emitted exclusively from petals, was emitted in lower quantities from open-pollinated flowers. Although, no differences in cinnamyl alcohol emissions were detected among three blueberry cultivars or at different times of day, some components of the blueberry floral blend were emitted in higher amounts from certain cultivars and at mid-day. Field observations showed that more bees visited bushes with pollinator-excluded flowers. Also, more honey bees were caught in traps baited with a synthetic blueberry floral blend than in unbaited traps. Greater volatile emissions may help guide bees to unpollinated flowers, and thus increase plant fitness and bee energetic return when foraging in blueberries. Furthermore, the variation in volatile emissions from blueberry flowers depending on pollination status, plant cultivar and time of day suggests an adaptive role of floral signals in increasing pollination of flowers.
Rodriguez-Saona, Cesar; Parra, Leonardo; Quiroz, Andrés; Isaacs, Rufus
Background and Aims Studies of the effects of pollination on floral scent and bee visitation remain rare, particularly in agricultural crops. To fill this gap, the hypothesis that bee visitation to flowers decreases after pollination through reduced floral volatile emissions in highbush blueberries, Vaccinium corymbosum, was tested. Other sources of variation in floral emissions and the role of floral volatiles in bee attraction were also examined. Methods Pollinator visitation to blueberry flowers was manipulated by bagging all flowers within a bush (pollinator excluded) or leaving them unbagged (open pollinated), and then the effect on floral volatile emissions and future bee visitation were measured. Floral volatiles were also measured from different blueberry cultivars, times of the day and flower parts, and a study was conducted to test the attraction of bees to floral volatiles. Key Results Open-pollinated blueberry flowers had 32 % lower volatile emissions than pollinator-excluded flowers. In particular, cinnamyl alcohol, a major component of the floral blend that is emitted exclusively from petals, was emitted in lower quantities from open-pollinated flowers. Although, no differences in cinnamyl alcohol emissions were detected among three blueberry cultivars or at different times of day, some components of the blueberry floral blend were emitted in higher amounts from certain cultivars and at mid-day. Field observations showed that more bees visited bushes with pollinator-excluded flowers. Also, more honey bees were caught in traps baited with a synthetic blueberry floral blend than in unbaited traps. Conclusions Greater volatile emissions may help guide bees to unpollinated flowers, and thus increase plant fitness and bee energetic return when foraging in blueberries. Furthermore, the variation in volatile emissions from blueberry flowers depending on pollination status, plant cultivar and time of day suggests an adaptive role of floral signals in
Full Text Available Mediator is a conserved multi-protein complex that plays an important role in regulating transcription by mediating interactions between transcriptional activator proteins and RNA polymerase II. Much evidence exists that Mediator plays a constitutive role in the transcription of all genes transcribed by RNA polymerase II. However, evidence is mounting that specific Mediator subunits may control the developmental regulation of specific subsets of RNA polymerase II-dependent genes. Although the Mediator complex has been extensively studied in yeast and mammals, only a few reports on Mediator function in flowering time control of plants, little is known about Mediator function in floral organ identity. Here we show that in Arabidopsis thaliana, MEDIATOR SUBUNIT 18 (MED18 affects flowering time and floral organ formation through FLOWERING LOCUS C (FLC and AGAMOUS (AG. A MED18 loss-of-function mutant showed a remarkable syndrome of later flowering and altered floral organ number. We show that FLC and AG mRNA levels and AG expression patterns are altered in the mutant. Our results support parallels between the regulation of FLC and AG and demonstrate a developmental role for Mediator in plants.
Full Text Available Angiosperm flowers are usually determinate structures that may produce seeds. In some species, flowers can revert from committed flower development back to an earlier developmental phase in a process called floral reversion. The allopolyploid Arabidopsis suecica displays photoperiod-dependent floral reversion in a subset of its flowers, yet little is known about the environmental conditions enhancing this phenotype, or the morphological processes leading to reversion. We have used light and electron microscopy to further describe this phenomenon. Additionally, we have further studied the phenology of flowering and floral reversion in A. suecica. In this study we confirm and expand upon our previous findings that floral reversion in the allopolyploid A. suecica is photoperiod-dependent, and show that its frequency is correlated with the timing for the onset of flowering. Our results also suggest that floral reversion in A. suecica displays natural variation in its penetrance between geographic populations of A. suecica.
Yan-Wen ZHANG; Xing-Nan ZHAO; Sheng-Jun HUANG; Li-Hui ZHANG; Ji-Min ZHAO
Floral color changes are common in Weigela and the retention of post-change flowers has been interpreted as a mechanism to increase attractiveness from a long distance and shorten pollinators' lingering time on the inflorescence(s) of individual plants.In the present study,we investigated the temporal pattern of floral color change and time required for pollen tube growth in the shrub Weigela japonica var.sinica.Over the 4-day anthesis,the color of the corolla in this species changes from white to red and the color cue changes from yellow to purple.The duration of both the white phase and the intermediate phase is approximately 1 day and the duration of the red phase is approximately 2 days.Our studies showed that color change in Weigela japonica var.sinica is age-dependent but independent of pollinator visits and flower pollination.Post-change flowers lost most of both the male and female residual reproductive ability and retained no rewards for pollinators.It took at least 3 days for a pollen tube to grow to the ovules and achieve fertilization.Thus,retention of post-change flowers is necessary for the completion of pollen tube growth.Our results indicate that the temporal pattern of color change and time requirement for pollen tube growth are most likely related events.
Vinícius Lourenço Garcia Brito
Full Text Available Floral color changes and retention of old flowers are frequently combined phenomena restricted to the floral guide or single flowers in few-flowered inflorescences. They are thought to increase the attractiveness over long distances and to direct nearby pollinators towards the rewarding flowers. In Tibouchina pulchra, a massively flowering tree, the whole flower changes its color during anthesis. On the first day, the flowers are white and on the next three days, they change to pink. This creates a new large-scale color pattern in which the white pre-changed flowers contrast against the pink post-changed ones over the entire tree. We describe the spectral characteristics of floral colors of T. pulchra and test bumblebees´ response to this color pattern when viewed at different angles (simulating long and short distances. The results indicated the role of different color components in bumblebee attraction and the possible scenario in which this flower color pattern has evolved. We tested bumblebees´ preference for simulated trees with 75% pink and 25% white flowers resembling the color patterns of T. pulchra, and trees with green leaves and pink flowers (control in long-distance approach. We also compared an artificial setting with three pink flowers and one white flower (T. pulchra model against four pink flowers with white floral guides (control in short-distance approach. Bumblebees spontaneously preferred the simulated T. pulchra patterns in both approaches despite similar rewards. Moreover, in short distances, pollinator visits to peripheral, non-rewarding flowers occurred only half as frequently in the simulated T. pulchra when compared to the control. Thefore, this exceptional floral color change and the retention of old flowers in T. pulchra favors the attraction of pollinators over long distances in a deception process while it honestly directs them towards the rewarding flowers at short distances possibly exploring their innate color
Fuentes, Jose D.; Chamecki, Marcelo; Roulston, T.'ai; Chen, Bicheng; Pratt, Kenneth R.
Flowers emit mixtures of scents that mediate plant-insect interactions such as attracting insect pollinators. Because of their volatile nature, however, floral scents readily react with ozone, nitrate radical, and hydroxyl radical. The result of such reactions is the degradation and the chemical modification of scent plumes downwind of floral sources. Large Eddy Simulations (LES) are developed to investigate dispersion and chemical degradation and modification of floral scents due to reactions with ozone, hydroxyl radical, and nitrate radical within the atmospheric surface layer. Impacts on foraging insects are investigated by utilizing a random walk model to simulate insect search behavior. Results indicate that even moderate air pollutant levels (e.g., ozone mixing ratios greater than 60 parts per billion on a per volume basis, ppbv) substantially degrade floral volatiles and alter the chemical composition of released floral scents. As a result, insect success rates of locating plumes of floral scents were reduced and foraging times increased in polluted air masses due to considerable degradation and changes in the composition of floral scents. Results also indicate that plant-pollinator interactions could be sensitive to changes in floral scent composition, especially if insects are unable to adapt to the modified scentscape. The increase in foraging time could have severe cascading and pernicious impacts on the fitness of foraging insects by reducing the time devoted to other necessary tasks.
By employing TCLs (thin cell layers) culture, the floral gradient in flowering tobacco of different developmental stages was confirmed. The TCLs from early flowering tobacco regenerated more floral buds than those from the tobacco plants in full blooming or fruiting stages. Analysis of free amino acid levels revealed the acropetal gradient of Pro in flowering tobacco stem. L-Pro. L-Trp. D,L-Met and L-Arg were respectively added into the culture medium for testing their influence on floral bud formation from tobacco pedicel segments. Only L-Trp evidently enhanced the floral bud neoformation.
Niwa, Masaki; Daimon, Yasufumi; Kurotani, Ken-ichi; Higo, Asuka; Pruneda-Paz, José L; Breton, Ghislain; Mitsuda, Nobutaka; Kay, Steve A; Ohme-Takagi, Masaru; Endo, Motomu; Araki, Takashi
Plant architecture shows a large degree of developmental plasticity. Some of the key determinants are the timing of the floral transition induced by a systemic flowering signal (florigen) and the branching pattern regulated by key factors such as BRANCHED1 (BRC1). Here, we report that BRC1 interacts with the florigen proteins FLOWERING LOCUS T (FT) and TWIN SISTER OF FT (TSF) but not with TERMINAL FLOWER1, a floral repressor. FT protein induced in leaves moves into the subtended bud, suggesting that FT protein also plays a role in promotion of the floral transition in the axillary meristem (AM). The brc1-2 mutant shows an earlier floral transition in the axillary shoots compared with the wild type, suggesting that BRC1 plays a role in delaying the floral transition of the AMs. Genetic and gene expression analyses suggest that BRC1 interferes with florigen (FT and TSF) function in the AMs. Consistent with this, BRC1 ectopically expressed in the shoot apical meristem delays the floral transition in the main shoot. These results taken together suggest that BRC1 protein interacts with FT and TSF proteins and modulates florigen activity in the axillary buds to prevent premature floral transition of the AMs.
Full Text Available Here, we report on the results of an experimental study that assessed the visitation frequency of wild bees to conspecific flowers with different sized floral guides. UV absorbent floral guides are ubiquitous in Angiosperms, yet surprisingly little is known about conspecific variation in these guides and very few studies have evaluated pollinator response to UV guide manipulation. This is true despite our rich understanding about learning and color preferences in bees. Historical dogma indicates that flower color serves as an important long-range visual signal allowing pollinators to detect the flowers, while floral guides function as close-range signals that direct pollinators to a reward. We initiated the work presented here by first assessing the population level variation in UV absorbent floral guides for conspecific flowers. We assessed two species, Rudbeckia hirta and R. fulgida. We then used several petal cut-and-paste experiments to test whether UV floral guides can also function to attract visitors. We manipulated floral guide size and evaluated visitation frequency. In all experiments, pollinator visitation rates were clearly associated with floral guide size. Diminished floral guides recruited relatively few insect visitors. Exaggerated floral guides recruited more visitors than smaller or average sized guides. Thus, UV floral guides play an important role in pollinator recruitment and in determining the relative attractiveness of conspecific flower heads. Consideration of floral guides is therefore important when evaluating the overall conspicuousness of flower heads relative to background coloration. This work raises the issue of whether floral guides serve as honest indicators of reward, since guide size varies in nature for conspecific flowers at the same developmental stage and since preferences for larger guides were found. To our knowledge, these are the first cut-and-paste experiments conducted to examine whether UV absorbent
Rogers, Hilary J
Flowers have a species-specific, limited life span with an irreversible programme of senescence, which is largely independent of environmental factors, unlike leaf senescence, which is much more closely linked with external stimuli. Life span of the whole flower is regulated for ecological and energetic reasons, but the death of individual tissues and cells within the flower is co-ordinated at many levels to ensure correct timing. Some floral cells die selectively during organ development, whereas others are retained until the whole organ dies. Pollination is an important floral cell death trigger in many species, and its effects are mediated by the plant growth regulator (PGR) ethylene. In some species ethylene is a major regulator of floral senescence, but in others it plays a very minor role and the co-ordinating signals involved remain elusive. Other PGRs such as cytokinin and brassinosteroids are also important but their role is understood only in some specific systems. In two floral cell types (the tapetum and the pollen-tube) there is strong evidence for apoptotic-type cell death, similar to that in animal cells. However, in petals there is stronger evidence for an autophagous type of cell death involving endoplasmic reticulum-derived vesicles and the vacuole. Proteases are important, and homologues to animal caspases, key regulators of animal cell death, exist in plants. However, their role is not yet clear. There are similarities to cell death in other plant organs, and many of the same genes are up-regulated in both leaf and petal senescence; however, there are also important differences for example in the role of PGRs. Understanding gene regulation may help to understand cell death in floral organs better, but alone it cannot provide all the answers.
Full Text Available The mechanism of floral transition in bamboo remains unclear. Dendrocalamus latiflorus (Bambusease, Bambusoideae, Poaceae is an economically and ecologically important clumping bamboo in tropical and subtropical areas. We evaluated morphological characteristics and gene expression profiling to study floral induction and early flower development in D. latiflorus. The detailed morphological studies on vegetative buds and floral organography were completed using paraffin sectioning and scanning electron microscopy. The 3 mm floral buds commence the development of stamen primordia and pistil primordium. Furthermore, homologs of floral transition-related genes, including AP1, TFL1, RFL, PpMADS1, PpMADS2, SPL9, FT, ID1, FCA, and EMF2, were detected and quantified by reverse transcriptase PCR and real-time PCR in vegetative and floral buds, respectively. Distinct expression profiles of ten putative floral initiation homologues that corresponded to the developmental stages defined by bud length were obtained and genes were characterized. Six of the genes (including DlTFL1, DlRFL, DlMADS2, DlID1, DlFCA, DlEMF2 showed statistically significant changes in expression during floral transition. DlAP1 demonstrated a sustained downward trend and could serve as a good molecular marker during floral transition in D. latiflorus. The combined analysis provided key candidate markers to track the transition from the vegetative to reproductive phase.
González-Varo, Juan P.; Ortiz-Sánchez, F. Javier; Vilà, Montserrat
Extreme specialization is a common phenomenon in antagonistic biotic interactions but it is quite rare in mutualistic ones. Indeed, bee specialization on a single flower species (monolecty) is a questioned fact. Here, we provide multiple lines of evidence on true monolecty in a solitary bee (Flavipanurgus venustus, Andrenidae), which is consistent across space (18 sites in SW Iberian Peninsula) and time (three years) despite the presence of closely related congeneric plant species whose flowers are morphologically similar. The host flower (Cistus crispus, Cistaceae) is in turn a supergeneralist, visited by at least 85 insect species. We uncover ultraviolet light reflectance as a distinctive visual cue of the host flower, which can be a key mechanism because bee specialization has an innate basis to recognize specific signals. Moreover, we hypothesized that a total dependence on an ephemeral resource (i.e. one flower species) must lead to spatiotemporal matching with it. Accordingly, we prove that the bee’s flight phenology is synchronized with the blooming period of the host flower, and that the densities of bee populations mirror the local densities of the host flower. This case supports the ‘predictable plethora’ hypothesis, that is, that host-specialization in bees is fostered by plant species providing predictably abundant floral resources. Our findings, along with available phylogenetic information on the genus Cistus, suggest the importance of historical processes and cognitive constraints as drivers of specialization in bee-plant interactions. PMID:27658205
Épocas de indução floral e soma térmica do período do florescimento à colheita de abacaxi 'Smooth Cayenne' Floral induction period and thermal time requirements from the flowering to the harvest period for Smooth Cayenne pineapple
Sergio Luiz Colucci de Carvalho
April treatment were smaller than the fruits from July. Period of floral induction had no effect on titratable acidity, total soluble solids and ratio of the fruits. The thermal time requirement from the flowering to the harvest period was 1,090 degree-days, with no statistical difference among treatments.
Full Text Available In Poland Galanthus nivalis L. is partially protected. The flowers of this species are one of the first sources of nectar and pollen for insects from February to April. The aim of this study was to present the flowering biology as well as the topography, anatomical, and ultrastructural features of the floral nectary. The flower lifespan, the breeding system, and the mass of pollen and nectar produced by the flowers were determined. Examination of the nectary structure was performed using light, fluorescence, scanning and transmission electron microscopy. The flower of G. nivalis lives for about 30 days. The stamens and pistils mature simultaneously and during this time nectar is secreted. The anthers of one flower produced the large amount of pollen (4 mg. The breeding system of G. nivalis was found to be characterized by partial self-compatibility, outcrossing, and xenogamy. The nectary is located at the top of the inferior ovary. The nectary epidermal cells are characterized by striated cuticular ornamentation. Initially, the secreted nectar formed vesicle-like protuberances under the cuticle. The epidermal and parenchymal cells contain numerous plastids, mitochondria, dictyosomes, ER cisterns, and vesicles fused with the plasmalemma, which indicates granulocrine nectar secretion.
Remay, Arnaud; Lalanne, David; Thouroude, Tatiana; Le Couviour, Fabien; Hibrand-Saint Oyant, Laurence; Foucher, Fabrice
Exhaustive studies on flowering control in annual plants have provided a framework for exploring this process in other plant species, especially in perennials for which little molecular data are currently available. Rose is a woody perennial plant with a particular flowering strategy--recurrent blooming, which is controlled by a recessive locus (RB). Gibberellins (GA) inhibit flowering only in non-recurrent roses. Moreover, the GA content varies during the flowering process and between recurrent and non-recurrent rose. Only a few rose genes potentially involved in flowering have been described, i.e. homologues of ABC model genes and floral genes from EST screening. In this study, we gained new information on the molecular basis of rose flowering: date of flowering and recurrent blooming. Based on a candidate gene strategy, we isolated genes that have similarities with genes known to be involved in floral control in Arabidopsis (GA pathway, floral repressors and integrators). Candidate genes were mapped on a segregating population, gene expression was studied in different organs and transcript abundance was monitored in growing shoot apices. Twenty-five genes were studied. RoFT, RoAP1 and RoLFY are proposed to be good floral markers. RoSPY and RB co-localized in our segregating population. GA metabolism genes were found to be regulated during floral transition. Furthermore, GA signalling genes were differentially regulated between a non-recurrent rose and its recurrent mutant. We propose that flowering gene networks are conserved between Arabidopsis and rose. The GA pathway appears to be a key regulator of flowering in rose. We postulate that GA metabolism is involved in floral initiation and GA signalling might be responsible for the recurrent flowering character.
The study of flower structure is essential in plant identification and in understanding sexual reproduction in plants, pollination syndromes, plant breeding, and fruit structure. Thus, study of flower structure and construction of floral formulae are standard parts of first-year university botany and biology courses. These activities involve…
Meulen-Muisers, van der J.J.M.; Oeveren, van J.C.; Sandbrink, J.M.; Tuyl, van J.M.
Floral bud abortion was found to be an undesirable source of non-genetic variation in breeding trials directed on the improvement of individual flower longevity in Asiatic hybrid lilies. It increased the longevity of the remaining flowers of the inflorescence. A similar response was found after elim
The study of flower structure is essential in plant identification and in understanding sexual reproduction in plants, pollination syndromes, plant breeding, and fruit structure. Thus, study of flower structure and construction of floral formulae are standard parts of first-year university botany and biology courses. These activities involve…
Funamoto, D; Ohashi, K
The discrepancy between observed flower visitors and those predicted based on floral phenotype has often cast doubt on the pollination syndrome concept. Here we show that this paradox may be alleviated by gaining better knowledge of the contributions of different flower visitors to pollination and the effects of floral traits that cannot be readily perceived by humans in Adenophora triphylla var. japonica. The blue, bell-shaped and pendant flowers of A. triphylla appear to fit a bee pollination syndrome. In contrast to this expectation, recent studies show that these flowers are frequented by nocturnal moths. We compared the flower visitor fauna, their visitation frequency and their relative contributions to seed set between day and night in two field populations of A. triphylla in Japan. We also determined the floral traits associated with temporal changes in the visitor assemblage, i.e. the timing of anthesis, the timing of changes in the sexual phase and the diel pattern of nectar production. While A. triphylla flowers were visited by both diurnal and nocturnal insects, the results from pollination experiments demonstrate that their primary pollinators are nocturnal settling-moths. Moreover, the flowers opened just after sunset, changed from staminate to pistillate phase in successive evenings and produced nectar only during the night, which all conform to the activity of nocturnal/crepuscular moths. Our study illustrates that the tradition of stereotyping the pollinators of a flower based on its appearance can be misleading and that it should be improved with empirical evidence of pollination performance and sufficient trait matching. © 2017 German Botanical Society and The Royal Botanical Society of the Netherlands.
Full Text Available El propósito de este trabajo fue caracterizar las fases fenológicas florales y determinar los visitantes florales en una población natural de Drimys granadensis (nombre común: canelo; Winteraceae ubicada en Altos de Yerbabuena ( 2.850 m , cerros orientales de la Sabana de Bogotá, (Colombia. El desarrollo fenológico floral duró 9,5 días cuando la floración ocurrió en época soleada, 12,5 días en época lluviosa y 16 días cuando se excluyeron a los visitantes florales mediante embolsado. Se realizaron observaciones del recurso utilizado, fase fenólogica de la flor visitada y cargas polínicas en los visitante florales, los cuales correspondieron a seis órdenes, 21 familias y 29 morfoespecies de insectos. Cuatro especies de coleópteros y dos de dípteros fueron considerados posibles polinizadores por su abundancia y carga de polen. Los resultados obtenidos se discuten en relación con aquellos reportados en otras especies del género Drimys y de la familia Winteraceae.The purpose of this research was to characterize the flowering phenological phases and to determine the flower visitors in a natural population of Drimys granadensis (common name: canelo; Winteraceae in Altos de Yerbabuena, eastern mountains of Sabana de Bogotá ( Colombia . Floral phenology development lasted 9.5 days when flowering occurred under sunny conditions, 12.5 days under rainy conditions and 16 days when flower visitors were excluded using cloth bags. It was done observations related with the resources used, the phenological phases of visited flowers and the pollen load on the flower visitors. Visitors corresponded with 29 morphospecies, 6 orders y 21 families of insects. Four species of coleoptera and two species of diptera were considered as possible pollinators taking in account abundance and pollen load. The results are analyzed in relation with those reported for other species in the genus Drimys and in the family Winteraceae.
Erin Jo Tiedeken
Full Text Available Invasive alien plants can compete with native plants for resources, and may ultimately decrease native plant diversity and/or abundance in invaded sites. This could have consequences for native mutualistic interactions, such as pollination. Although invasive plants often become highly connected in plant-pollinator interaction networks, in temperate climates they usually only flower for part of the season. Unless sufficient alternative plants flower outside this period, whole-season floral resources may be reduced by invasion. We hypothesized that the cessation of flowering of a dominant invasive plant would lead to dramatic, seasonal compositional changes in plant-pollinator communities, and subsequent changes in network structure. We investigated variation in floral resources, flower-visiting insect communities, and interaction networks during and after the flowering of invasive Rhododendron ponticum in four invaded Irish woodland sites. Floral resources decreased significantly after R. ponticum flowering, but the magnitude of the decrease varied among sites. Neither insect abundance nor richness varied between the two periods (during and after R. ponticum flowering, yet insect community composition was distinct, mostly due to a significant reduction in Bombus abundance after flowering. During flowering R. ponticum was frequently visited by Bombus; after flowering, these highly mobile pollinators presumably left to find alternative floral resources. Despite compositional changes, however, network structural properties remained stable after R. ponticum flowering ceased: generality increased, but quantitative connectance, interaction evenness, vulnerability, H'2 and network size did not change. This is likely because after R. ponticum flowering, two to three alternative plant species became prominent in networks and insects increased their diet breadth, as indicated by the increase in network-level generality. We conclude that network structure
Andrew V. Novikoff
Full Text Available Species of the tribe Delphinieae have dorsoventralized flowers; their pentamerous calyx and reduced corolla are dorsally spurred and inner spurs are nectariferous. Based on this common floral scheme, Delphinieae species exhibit a wide diversity of floral structures and morphologies. We present here the first investigation of the floral anatomy in Delphinieae. The organization of the floral vascular system has been studied in species representative of the floral morphological diversity of Delphinieae: Aconitum lasiocarpum, Delphinium elatum, and Consolida regalis. The three species show a similar vascularization of the calyx and of the reproductive organs, but exhibit distinct anatomical features in the corolla where the nectaries are borne. The sepals and the stamens have a trilacunar three-traced and a unilacunar one-traced vascularization, respectively. Three free carpels in D. elatum and A. lasiocarpum are basically supplied by six vascular bundles – three independent dorsal bundles and three fused lateral bundles. In C. regalis the single carpel is supplied by three independent vascular bundles (one dorsal and two ventral. Staminodes are not vascularized. The basic type of petal vascularization is unilacunar one-traced, but in the case of C. regalis the derived bilacunar two-traced type has been observed. This latter state arose as a result of the fusion of the two dorsal petal primordia. The results of this first comparative study of the floral anatomy of Delphinieae are discussed with the recent phylogenetic, morphological, and evo-devo findings concerning the tribe.
Poyatos-Pertíñez, Sandra; Quinet, Muriel; Ortíz-Atienza, Ana; Yuste-Lisbona, Fernando J; Pons, Clara; Giménez, Estela; Angosto, Trinidad; Granell, Antonio; Capel, Juan; Lozano, Rafael
Floral organogenesis requires coordinated interactions between genes specifying floral organ identity and those regulating growth and size of developing floral organs. With the aim to isolate regulatory genes linking both developmental processes (i.e., floral organ identity and growth) in the tomato model species, a novel mutant altered in the formation of floral organs was further characterized. Under normal growth conditions, floral organ primordia of mutant plants were correctly initiated, however, they were unable to complete their development impeding the formation of mature and fertile flowers. Thus, the growth of floral buds was blocked at an early stage of development; therefore, we named this mutant as unfinished flower development (ufd). Genetic analysis performed in a segregating population of 543 plants showed that the abnormal phenotype was controlled by a single recessive mutation. Global gene expression analysis confirmed that several MADS-box genes regulating floral identity as well as other genes participating in cell division and different hormonal pathways were affected in their expression patterns in ufd mutant plants. Moreover, ufd mutant inflorescences showed higher hormone contents, particularly ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC) and strigol compared to wild type. Such results indicate that UFD may have a key function as positive regulator of the development of floral primordia once they have been initiated in the four floral whorls. This function should be performed by affecting the expression of floral organ identity and growth genes, together with hormonal signaling pathways.
Full Text Available Floral organogenesis requires coordinated interactions between genes specifying floral organ identity and those regulating growth and size of developing floral organs. With the aim to isolate regulatory genes linking both developmental processes (i.e. floral organ identity and growth in the tomato model species, a novel mutant altered in the formation of floral organs was further characterized. Under normal growth conditions, floral organ primordia of mutant plants were correctly initiated, however, they were unable to complete their development impeding the formation of mature and fertile flowers. Thus, the growth of floral buds was blocked at an early stage of development; therefore, we named this mutant as unfinished flower development (ufd. Genetic analysis performed in a segregating population of 543 plants showed that the abnormal phenotype was controlled by a single recessive mutation. Global gene expression analysis confirmed that several MADS-box genes regulating floral identity as well as other genes participating in cell division and different hormonal pathways were affected in their expression patterns in ufd mutant plants. Moreover, ufd mutant inflorescences showed higher hormone contents, particularly ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC and strigol compared to wild type. Such results indicate that UFD may have a key function as positive regulator of the development of floral primordia once they have been initiated in the four floral whorls. This function should be performed by affecting the expression of floral organ identity and growth genes, together with hormonal signalling pathways.
Bunya-atichart, K.; Ketsa, S.; Doorn, van W.G.
We studied the abscission of floral buds and open flowers in cut Dendrobium inflorescences. Abscission of floral buds was high and sensitive to ethylene in all cultivars studied. Many open flowers abscised in most cultivars, but cv. Willie exhibited only small amount of floral fall and cv. Miss Teen
Insect-pollinated plants have developed showy flowers and floral displays that attract pollinators. Pollinators, in turn, show preferences for specific floral traits and their foraging behavior is influenced by floral traits. In this study, we examined the preference of bumble bees for flower size, ...
Ionescu, Irina Alexandra; Møller, Birger Lindberg; Sánchez Pérez, Raquel
the transition to flowering as well as flower opening. Increased emphasis on research within this area has the potential to counteract the negative effects of global warming on flowering time, especially in perennial crop plants. Perennial crops have a requirement for winter chill, but winters become...... increasingly warm in temperate regions. This has dramatic effects on crop yield. Different strategies are therefore being developed to engineer flowering time to match local growing conditions. The majority of these efforts are within plant breeding, which benefits from a substantial amount of knowledge...... on the genetic aspects of flowering time regulation in annuals, but less so in perennials. An alternative to plant breeding approaches is to engineer flowering time chemically via the external application of flower-inducing compounds. This review discusses a variety of exogenously applied compounds used in fruit...
Soil salinity is one of the most serious agricultural problems that significantly reduce crop yields in the aridand semi-arid regions. It influences various phases of plant growth and developmental processes, such as seed germina-tion, leaf and stem growth, and reproductive propagation. Salt stress delays the onset of flowering in many plant spe-cies. We have previously reported that the Arabidopsis BROTHER OF FT AND TFL1 （BFT） acts as a floral repressor undersalt stress. However, the molecular mechanisms underlying the BFT function in the salt regulation of flowering inductionis unknown. In this work, we found that BFT delays flowering under high salinity by competing with FLOWERING LOCUST （FT） for binding to the FD transcription factor. The flowering time of FD-deficient fd-2 mutant was insensitive to highsalinity. BFT interacts with FD in the nucleus via the C-terminal domain of FD, which is also required for the interactionof FD with FT, and interferes with the FT-FD interaction. These observations indicate that BFT constitutes a distinct saltstress signaling pathway that modulates the function of the FT-FD module and possibly provides an adaptation strategythat fine-tunes photoperiodic flowering under high salinity.
Berrached, Rachda; Kadik, Leila; Ait Mouheb, Hocine; Prinzing, Andreas
Strong seasonality in abiotic harshness and pollinator availability shape the reproductive success of plants. Plant species can avoid or can tolerate harsh abiotic conditions and can attract different pollinators, but it remains unknown (i) which of these capacities is most important for flowering phenology, (ii) whether tolerance/avoidance of abiotic harshness reinforces or relaxes the phenological differentiation of species attracting different pollinators. We assembled possibly the first functional trait database for a North African steppe covering 104 species. We inferred avoidance of harshness (drought) from dormancy, i.e. annual life-span and seed size. We inferred tolerance or resistance to harshness from small specific leaf area, small stature, deep roots and high dry matter content. We inferred the type of pollinators attracted from floral colour, shape and depth. We found that avoidance traits did not affect flowering phenology, and among tolerance traits only deep roots had an effect by delaying flowering. Flower colour (red or purple), and occasionally flower depth, delayed flowering. Dish, gullet and flag shape accelerated flowering. Interactive effects however were at least as important, inversing the mentioned relationship between floral characters and flowering phenology. Specifically, among drought-tolerant deep-rooted species, flowering phenologies converged among floral types attracting different pollinators, without becoming less variable overall. Direct and interactive effects of root depth and floral traits explained at least 45% of the variance in flowering phenology. Also, conclusions on interactive effects were highly consistent with and without including information on family identity or outliers. Overall, roots and floral syndromes strongly control flowering phenology, while many other traits do not. Surprisingly, floral syndromes and the related pollinators appear to constrain phenology mainly in shallow-rooted, abiotically little
Riboni, Matteo; Robustelli Test, Alice; Galbiati, Massimo; Tonelli, Chiara; Conti, Lucio
Plants maximize their chances to survive adversities by reprogramming their development according to environmental conditions. Adaptive variations in the timing to flowering reflect the need for plants to set seeds under the most favorable conditions. A complex network of genetic pathways allows plants to detect and integrate external (e.g., photoperiod and temperature) and/or internal (e.g., age) information to initiate the floral transition. Furthermore different types of environmental stresses play an important role in the floral transition. The emerging picture is that stress conditions often affect flowering through modulation of the photoperiodic pathway. In this review we will discuss different modes of cross talk between stress signaling and photoperiodic flowering, highlighting the central role of the florigen genes in this process.
Khan, Muhammad Rehman Gul; Ai, Xiao-Yan; Zhang, Jin-Zhi
Flowering time plays a significant role in the reproductive success of plants. So far, five major pathways to flowering have been characterized in Arabidopsis, including environmental induction through photoperiod, vernalization, and gibberellins and autonomous floral iation, and aging by sequentially operating miRNAs (typically miR156 and miR172) responding to endogenous cues. The balance of signals from these pathways is integrated by a common set of genes (FLOWERING LOCUS C, FLOWERING LOCUS T, LEAFY, and SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1) that determine the flowering time. Recent studies have indicated that epigenetic modification, alternative splicing, antisense RNA and chromatin silencing regulatory mechanisms play an important role in this process by regulating related flowering gene expression. In this review, we discuss the current understanding in genetic regulation of the phase transition from vegetative to reproductive growth by using Arabidopsis as a model. We also describe how this knowledge has been successfully applied for identifying homologous genes from perennial crops. Furthermore, detailed analysis of the similarities and differences between annual and perennial plants flowering will help elucidate the mechanisms of perennial plant maturation and regulation of floral initiation.
Full Text Available The transition from vegetative growth to floral meristems in higher plants is regulated through the integration of internal cues and environmental signals. We were interested to examine the molecular mechanism of flowering in the day-neutral plant tomato (Solanum lycopersicum L. and the effect of environmental conditions on tomato flowering. Analysis of the tomato genome uncovered 13 PEBP (phosphatidylethanolamine-binding protein genes, and found six of them were FT-like genes which named as SlSP3D, SlSP6A, SlSP5G, SlSP5G1, SlSP5G2 and SlSP5G3. 6 FT-like genes were analyzed to clarify their functional roles in flowering using transgenic and expression analyses. We found that SlSP5G, SlSP5G2 and SlSP5G3 proteins were floral inhibitors whereas only SlSP3D/SFT (SINGLE FLOWER TRUSS was a floral inducer. SlSP5G was expressed at higher levels in long day (LD conditions compared to short day (SD conditions while SlSP5G2 and SlSP5G3 showed the opposite expression patterns. The silencing of SlSP5G by VIGS (Virus induced gene silencing resulted in tomato plants that flowered early under LD conditions and the silencing of SlSP5G2 and SlSP5G3 led to early flowering under SD conditions. The higher expression levels of SlSP5G under LD conditions were not seen in phyB1 mutants, and the expression levels of SlSP5G2 and SlSP5G3 were increased in phyB1 mutants under both SD and LD conditions compared to wild type plants. These data suggest that SlSP5G, SlSP5G2 and SlSP5G3 are controlled by photoperiod, and the different expression patterns of FT-like genes under different photoperiod may contribute to tomato being a day neutral plant. In addition, PHYB1 mediate the expression of SlSP5G, SlSP5G2 and SlSP5G3 to regulate flowering in tomato.
Higuchi, Yohei; Hisamatsu, Tamotsu
Chrysanthemums require repeated cycles of short-day (SD) photoperiod for successful anthesis, but their vegetative state is strictly maintained under long-day (LD) or night-break (NB) conditions. We have previously demonstrated that photoperiodic flowering of a wild diploid chrysanthemum (Chrysanthemum seticuspe f. boreale) is controlled by a pair of systemic floral regulators, florigen (CsFTL3) and anti-florigen (CsAFT), produced in the leaves. Here, we report the functional characterisation of a local floral regulator, CsTFL1, a chrysanthemum orthologue of TERMINAL FLOWER 1 gene in Arabidopsis. Constitutive expression of CsTFL1 in C. seticuspe (CsTFL1-ox) resulted in extremely late flowering under SD and prevented up-regulation of floral meristem identity genes in shoot tips and leaves. Bimolecular fluorescence complementation assay showed that both CsTFL1 and CsFTL3 interacted with CsFDL1, a bZIP transcription factor FD homologue, in the nucleus. The transient gene expression assay indicated that CsTFL1 suppresses flowering by directly antagonising the flower inductive activity of the CsFTL3-CsFDL1 complex. Our results suggest that strict maintenance of vegetative state under non-inductive photoperiod is achieved by the coordinated action of both the systemic floral inhibitor and local floral inhibitor CsTFL1, which is constitutively expressed in shoot tips.
Seymour, Roger S
Effect of size of inflorescences, flowers and cones on maximum rate of heat production is analysed allometrically in 23 species of thermogenic plants having diverse structures and ranging between 1.8 and 600 g. Total respiration rate (, micromol s(-1)) varies with spadix mass (M, g) according to in 15 species of Araceae. Thermal conductance (C, mW degrees C(-1)) for spadices scales according to C = 18.5M(0.73). Mass does not significantly affect the difference between floral and air temperature. Aroids with exposed appendices with high surface area have high thermal conductance, consistent with the need to vaporize attractive scents. True flowers have significantly lower heat production and thermal conductance, because closed petals retain heat that benefits resident insects. The florets on aroid spadices, either within a floral chamber or spathe, have intermediate thermal conductance, consistent with mixed roles. Mass-specific rates of respiration are variable between species, but reach 900 nmol s(-1) g(-1) in aroid male florets, exceeding rates of all other plants and even most animals. Maximum mass-specific respiration appears to be limited by oxygen delivery through individual cells. Reducing mass-specific respiration may be one selective influence on the evolution of large size of thermogenic flowers.
de Vere, Natasha; Jones, Laura E; Gilmore, Tegan; Moscrop, Jake; Lowe, Abigail; Smith, Dan; Hegarty, Matthew J; Creer, Simon; Ford, Col R
Understanding which flowers honey bees (Apis mellifera) use for forage can help us to provide suitable plants for healthy honey bee colonies. Accordingly, honey DNA metabarcoding provides a valuable tool for investigating pollen and nectar collection. We investigated early season (April and May) floral choice by honey bees provided with a very high diversity of flowering plants within the National Botanic Garden of Wales. There was a close correspondence between the phenology of flowering and the detection of plants within the honey. Within the study area there were 437 genera of plants in flower during April and May, but only 11% of these were used. Thirty-nine plant taxa were recorded from three hives but only ten at greater than 1%. All three colonies used the same core set of native or near-native plants, typically found in hedgerows and woodlands. The major plants were supplemented with a range of horticultural species, with more variation in plant choice between the honey bee colonies. We conclude that during the spring, honey bees need access to native hedgerows and woodlands to provide major plants for foraging. Gardens provide supplementary flowers that may increase the nutritional diversity of the honey bee diet.
de Vere, Natasha; Jones, Laura E.; Gilmore, Tegan; Moscrop, Jake; Lowe, Abigail; Smith, Dan; Hegarty, Matthew J.; Creer, Simon; Ford, Col R.
Understanding which flowers honey bees (Apis mellifera) use for forage can help us to provide suitable plants for healthy honey bee colonies. Accordingly, honey DNA metabarcoding provides a valuable tool for investigating pollen and nectar collection. We investigated early season (April and May) floral choice by honey bees provided with a very high diversity of flowering plants within the National Botanic Garden of Wales. There was a close correspondence between the phenology of flowering and the detection of plants within the honey. Within the study area there were 437 genera of plants in flower during April and May, but only 11% of these were used. Thirty-nine plant taxa were recorded from three hives but only ten at greater than 1%. All three colonies used the same core set of native or near-native plants, typically found in hedgerows and woodlands. The major plants were supplemented with a range of horticultural species, with more variation in plant choice between the honey bee colonies. We conclude that during the spring, honey bees need access to native hedgerows and woodlands to provide major plants for foraging. Gardens provide supplementary flowers that may increase the nutritional diversity of the honey bee diet. PMID:28205632
Full Text Available BACKGROUND: As an arborescent and perennial plant, Moso bamboo (Phyllostachys edulis (Carrière J. Houzeau, synonym Phyllostachys heterocycla Carrière is characterized by its infrequent sexual reproduction with flowering intervals ranging from several to more than a hundred years. However, little bamboo genomic research has been conducted on this due to a variety of reasons. Here, for the first time, we investigated the transcriptome of developing flowers in Moso bamboo by using high-throughput Illumina GAII sequencing and mapping short reads to the Moso bamboo genome and reference genes. We performed RNA-seq analysis on four important stages of flower development, and obtained extensive gene and transcript abundance data for the floral transcriptome of this key bamboo species. RESULTS: We constructed a cDNA library using equal amounts of RNA from Moso bamboo leaf samples from non-flowering plants (CK and mixed flower samples (F of four flower development stages. We generated more than 67 million reads from each of the CK and F samples. About 70% of the reads could be uniquely mapped to the Moso bamboo genome and the reference genes. Genes detected at each stage were categorized to putative functional categories based on their expression patterns. The analysis of RNA-seq data of bamboo flowering tissues at different developmental stages reveals key gene expression properties during the flower development of bamboo. CONCLUSION: We showed that a combination of transcriptome sequencing and RNA-seq analysis was a powerful approach to identifying candidate genes related to floral transition and flower development in bamboo species. The results give a better insight into the mechanisms of Moso bamboo flowering and ageing. This transcriptomic data also provides an important gene resource for improving breeding for Moso bamboo.
flowering rates were identified using the model coefficients. Flower abortion among hybrids ranged from 10.53 to 45.96% and was correlated with temperature and hydric demand of the atmosphere. Genotypes with larger thermal times between the peak and the end of flowering generally had higher percentages of flower abortion. The adjustment of data from flower emission to those of the thermal sum of the flowering period, using a logistic model, allows simulating floral dynamics of hybrids of canola and Indian mustard.
Zhang, Songwen; Zhang, Dong; Fan, Sheng; Du, Lisha; Shen, Yawen; Xing, Libo; Li, Youmei; Ma, Juanjuan; Han, Mingyu
Gibberellins (GAs) reduce apple (Malus domestica) flowering rates; however, the mechanism of their action is not fully understood. To gain a better insight into gibberellin-regulated flowering, here, 5 year-old 'Fuji' apple trees were used to explore the responses of hormones [GA1+3, GA4+7, indole-3-acetic acid (IAA), zeatin-riboside (ZR), and abscisic acid (ABA)], and gibberellin- and flowering-associated genes, to applications of gibberellin acid (GA3) and paclobutrazol (PAC). Results showed that GA3 relatively stimulated vegetative growth and delayed floral induction. Moreover, GA3 spraying significantly affected contents of all endogenous hormones and all the genes tested in at least one time points: the content of endogenous GAs was increased instantly and that of ZR was reduced at 44 days after fullbloom (DAF), which might constitute an unfavorable factor for flower formation; MdKO (ent-kaurene oxidase gene) and MdGA20ox (GA20 oxidase gene) were significantly repressed by a high level of GAs through the negative feedback regulation of GA; additionally, the MdSPLs (SQUAMOSA-PROMOTER BINDING PROTEIN-LIKE) in this study were all significantly repressed by GA3 but promoted by PAC; the expression of MdFT1/2 (FLOWERING LOCUS T), MdSOC1 (SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1) and MdAP1 (APETALA1) in GA3-treated buds changed in the same way, and they were repressed at 44 DAF. We suppose that GA3 spraying disrupts the balance between ZR and GAs, and inhibits floral induction, probably by suppressing MdSPLs and the floral integrators in flower induction, which ultimately contributed to inhibiting flower formation. Copyright © 2016 Elsevier Masson SAS. All rights reserved.
Zhao, Yafei; Zhang, Teng; Broholm, Suvi K; Tähtiharju, Sari; Mouhu, Katriina; Albert, Victor A; Teeri, Teemu H; Elomaa, Paula
The evolutionary success of Asteraceae, the largest family of flowering plants, has been attributed to the unique inflorescence architecture of the family, which superficially resembles an individual flower. Here, we show that Asteraceae inflorescences (flower heads, or capitula) resemble solitary flowers not only morphologically but also at the molecular level. By conducting functional analyses for orthologs of the flower meristem identity genes LEAFY (LFY) and UNUSUAL FLORAL ORGANS (UFO) in Gerbera hybrida, we show that GhUFO is the master regulator of flower meristem identity, while GhLFY has evolved a novel, homeotic function during the evolution of head-like inflorescences. Resembling LFY expression in a single flower meristem, uniform expression of GhLFY in the inflorescence meristem defines the capitulum as a determinate structure that can assume floral fate upon ectopic GhUFO expression. We also show that GhLFY uniquely regulates the ontogeny of outer, expanded ray flowers but not inner, compact disc flowers, indicating that the distinction of different flower types in Asteraceae is connected with their independent evolutionary origins from separate branching systems. © 2016 American Society of Plant Biologists. All rights reserved.
Johansson, Mikael; Staiger, Dorothee
Plants precisely time the onset of flowering to ensure reproductive success. A major factor in seasonal control of flowering time is the photoperiod. The length of the daily light period is measured by the circadian clock in leaves, and a signal is conveyed to the shoot apex to initiate floral transition accordingly. In the last two decades, the molecular players in the photoperiodic pathway have been identified in Arabidopsis thaliana. Moreover, the intricate connections between the circadian clockwork and components of the photoperiodic pathway have been unravelled. In particular, the molecular basis of time-of-day-dependent sensitivity to floral stimuli, as predicted by Bünning and Pittendrigh, has been elucidated. This review covers recent insights into the molecular mechanisms underlying clock regulation of photoperiodic responses and the integration of the photoperiodic pathway into the flowering time network in Arabidopsis. Furthermore, examples of conservation and divergence in photoperiodic flower induction in other plant species are discussed. © The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: email@example.com.
Abel Augusto Conceição
Full Text Available The species Vellozia sincorana L.B.Sm. & Ayensu is key to biodiversity conservation in the tropical mountain region of Brazil. The massive post-fire flowering of this endemic species provides a large, episodic supply of floral resources, mostly nectar, to animals.
Matteson, K.C.; Grace, James B.; Minor, E.S.
Although urban areas are often considered to have uniformly negative effects on biodiversity, cities are most accurately characterized as heterogeneous mosaics of buildings, streets, parks, and gardens that include both ‘good’ and ‘bad’ areas for wildlife. However, to date, few studies have evaluated how human impacts vary in direction and magnitude across a heterogeneous urban landscape. In this study, we assessed the distribution of floral resources and flower-visiting insects across a variety of land uses in New York City. We visited both green spaces (e.g. parks, cemeteries) and heavily developed neighborhood blocks (e.g. with high or low density residential zoning) and used structural equation modeling (SEM) to evaluate the direct and indirect effects of median income, vegetation, and development intensity on floral resources and insects in both settings. Abundance and taxonomic richness of flower-visiting insects was significantly greater in green spaces than neighborhood blocks. The SEM results indicated that heavily-developed neighborhoods generally had fewer flower-visiting insects consistent with reductions in floral resources. However, some low-density residential neighborhoods maintained high levels of floral resources and flower-visiting insects. We found that the effects of surrounding vegetation on floral resources, and thus indirect effects on insects, varied considerably between green spaces and neighborhood blocks. Along neighborhood blocks, vegetation consisted of a mosaic of open gardens and sparsely distributed trees and had a positive indirect effect on flower-visiting insects. In contrast, vegetation in urban green spaces was associated with increased canopy cover and thus had a negative indirect effect on flower-visiting insects through reductions in floral resources. In both neighborhood blocks and green spaces, vegetation had a positive direct effect on flower-visiting insects independent of the influence of vegetation on floral
Hardy, C R; Stevenson, D W; Kiss, H G
The flowers of Dichorisandra thyrsiflora (Commelinaceae) are monosymmetric and composed of three sepals, three petals, six stamens, and three connate carpels. The anthers are poricidal and possess a wall of five cell layers (tapetum included). This type of anther wall, not previously observed in the Commelinaceae, is developmentally derived from the monocotyledonous type via an additional periclinal division and the persistence of the middle layers through anther dehiscence. Secondary endothecial thickenings develop in the cells of the two middle layers only. The tapetum is periplasmodial and contains raphides. Microsporogenesis is successive and yields both decussate and isobilateral tetrads. Pollen is shed as single binucleate grains. The gynoecium is differentiated into a globose ovary, hollow elongate style, and trilobed papillate stigma. Each locule contains six to eight hemianatropous to slightly campylotropous crassinucellar ovules with axile (submarginal) placentation. The ovules are bitegmic with a slightly zig-zag micropyle. Megagametophyte development is of the Polygonum type. The mature megagametophyte consists of an egg apparatus and fusion nucleus; the antipodals having degenerated. The floral vasculature is organized into an outer and inner system of bundles in the pedicel. The outer system becomes ventral carpellary bundles. All other floral vascular traces originate from the inner system.
Ingram, G C; Goodrich, J; Wilkinson, M D; Simon, R; Haughn, G W; Coen, E S
The unusual floral organs (ufo) mutant of Arabidopsis has flowers with variable homeotic organ transformations and inflorescence-like characteristics. To determine the relationship between UFO and previously characterized meristem and organ identity genes, we cloned UFO and determined its expression pattern. The UFO gene shows extensive homology with FIMBRIATA (FIM), a gene mediating between meristem and organ identity genes in Antirrhinum. All three UFO mutant alleles that we sequenced are predicted to produce truncated proteins. UFO transcripts were first detected in early floral meristems, before organ identity genes had been activated. At later developmental stages, UFO expression is restricted to the junction between sepal and petal primordia. Phenotypic, genetic, and expression pattern comparisons between UFO and FIM suggest that they are cognate homologs and play a similar role in mediating between meristem and organ identity genes. However, some differences in the functions and genetic interactions of UFO and FIM were apparent, indicating that changes in partially redundant pathways have occurred during the evolutionary divergence of Arabidopsis and Antirrhinum.
Full Text Available Sugar apple (Annona squamosa L. is a semi-deciduous subtropical tree that progressively sheds its leaves in the spring. However, little information is available on the mechanism involved in flower developmental pattern. To gain a global perspective on the floral transition and flower development of sugar apple, cDNA libraries were prepared independently from inflorescent meristem and three flowering stages. Illumina sequencing generated 107,197,488 high quality reads that were assembled into 71,948 unigenes, with an average sequence length of 825.40 bp. Among the unigenes, various transcription factor families involved in floral transition and flower development were elucidated. Furthermore, a Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis revealed that unigenes exhibiting differential expressions were involved in various phytohormone signal transduction events and circadian rhythms. In addition, 147 unigenes exhibiting sequence similarities to known flowering-related genes from other plants were differentially expressed during flower development. The expression patterns of 20 selected genes were validated using quantitative-PCR. The expression data presented in our study is the most comprehensive dataset available for sugar apple so far and will serve as a resource for investigating the genetics of the flowering process in sugar apple and other Annona species.
Ryu, Jae Yong; Park, Chung-Mo; Seo, Pil Joon
Floral transition is coordinately regulated by both endogenous and exogenous cues to ensure reproductive success under fluctuating environmental conditions. Abiotic stress conditions, including drought and high salinity, also have considerable influence on this developmental process. However, the signaling components and molecular mechanisms underlying the regulation of floral transition by environmental factors have not yet been defined. In this work, we show that the Arabidopsis BROTHER OF FT AND TFL1 (BFT) gene, which encodes a member of the FLOWERING LOCUS T (FT)/TERMINAL FLOWER 1 (TFL1) family, regulates floral transition under conditions of high salinity. The BFT gene was transcriptionally induced by high salinity in an abscisic acid (ABA)-dependent manner. Transgenic plants overexpressing the BFT gene (35S:BFT) and BFT-deficient mutant (bft-2) plants were phenotypically indistinguishable from Col-0 plants in seed germination and seedling growth under high salinity. In contrast, although the floral transition was delayed significantly in Col-0 plants under high salinity, that of the bft-2 mutant was not affected by high salinity. We also observed that expression of the APETALA1 (AP1) gene was suppressed to a lesser degree in the bft-2 mutant than in Col-0 plants. Taken together, our observations suggest that BFT mediates salt stress-responsive flowering, providing an adaptive strategy that ensures reproductive success under unfavorable stress conditions.
Collier, Matthew H; Rogstad, Steven H
We investigated the hypothesis that dandelion clones (Taraxacum officinale Weber, sensu lato; Asteraceae) differ in their floral stage timing characteristics under a constant set of environmental conditions. To test this hypothesis, plants representing nine different dandelion clones (identified by DNA fingerprinting) were grown in groups of five (N = 45) in a growth chamber for a period of 8 mo, with chamber settings similar to environmental conditions at peak dandelion flowering time for their population sites. Five flowering phenology parameters were monitored daily for a total of 301 buds developing during this time: (1) time to bud; (2) time to full opening and inflorescence maturation (i.e., first anthesis); (3) time to re-closure of an inflorescence; (4) time to fruit (full re-opening of the inflorescence); and (5) total flowering time. Scape length at the appearance of a fully expanded infructescence was also measured for each individual. Significant differences in mean time to inflorescence, mean time to re-closure, mean time to fruit, and mean total flowering time were revealed among some dandelion clones (Kruskal-Wallis, P ≤ 0.0005). No differences in mean number of inflorescence buds per plant (P = 0.2217), mean time to bud (P = 0.2396), or mean scape length (P = 0.3688) were detected among the nine clones. These results suggest that differences in floral stage timing may in part involve varying genotypic environmental response characteristics and that these differences may have potential fitness effects. Further research is needed to determine if such clonal differences are observed under a broader range of uniform environmental conditions.
Jagadish, S V Krishna; Bahuguna, Rajeev N; Djanaguiraman, Maduraimuthu; Gamuyao, Rico; Prasad, P V Vara; Craufurd, Peter Q
Flowering is a crucial determinant for plant reproductive success and seed-set. Increasing temperature and elevated carbon-dioxide (e[CO2]) are key climate change factors that could affect plant fitness and flowering related events. Addressing the effect of these environmental factors on flowering events such as time of day of anthesis (TOA) and flowering time (duration from germination till flowering) is critical to understand the adaptation of plants/crops to changing climate and is the major aim of this review. Increasing ambient temperature is the major climatic factor that advances flowering time in crops and other plants, with a modest effect of e[CO2].Integrated environmental stimuli such as photoperiod, temperature and e[CO2] regulating flowering time is discussed. The critical role of plant tissue temperature influencing TOA is highlighted and crop models need to substitute ambient air temperature with canopy or floral tissue temperature to improve predictions. A complex signaling network of flowering regulation with change in ambient temperature involving different transcription factors (PIF4, PIF5), flowering suppressors (HvODDSOC2, SVP, FLC) and autonomous pathway (FCA, FVE) genes, mainly from Arabidopsis, provides a promising avenue to improve our understanding of the dynamics of flowering time under changing climate. Elevated CO2 mediated changes in tissue sugar status and a direct [CO2]-driven regulatory pathway involving a key flowering gene, MOTHER OF FT AND TFL1 (MFT), are emerging evidence for the role of e[CO2] in flowering time regulation.
Full Text Available The quantification of floral shape variations is difficult because flower structures are both diverse and complex. Traditionally, floral shape variations are quantified using the qualitative and linear measurements of two-dimensional (2D images. The 2D images cannot adequately describe flower structures, and thus lead to unsatisfactory discrimination of the flower shape. This study aimed to acquire three-dimensional (3D images by using microcomputed tomography (μCT and to examine the floral shape variations by using geometric morphometrics (GM. To demonstrate the advantages of the 3D-µCT-GM approach, we applied the approach to a second-generation population of florist’s gloxinia (Sinningia speciosa crossed from parents of zygomorphic and actinomorphic flowers. The flowers in the population considerably vary in size and shape, thereby served as good materials to test the applicability of the proposed phenotyping approach. Procedures were developed to acquire 3D volumetric flower images using a μCT scanner, to segment the flower regions from the background, and to select homologous characteristic points (i.e., landmarks from the flower images for the subsequent GM analysis. The procedures identified 95 landmarks for each flower and thus improved the capability of describing and illustrating the flower shapes, compared with typically lower number of landmarks in 2D analyses. The GM analysis demonstrated that flower opening and dorsoventral symmetry were the principal shape variations of the flowers. The degrees of flower opening and corolla asymmetry were then subsequently quantified directly from the 3D flower images. The 3D-µCT-GM approach revealed shape variations that could not be identified using typical 2D approaches and accurately quantified the flower traits that presented a challenge in 2D images. The approach opens new avenues to investigate floral shape variations.
Steinbach, Yvonne; Hennig, Lars
Appropriate timing of flowering is crucial for crop yield and the reproductive success of plants. Flowering can be induced by a number of molecular pathways that respond to internal and external signals such as photoperiod, vernalization or light quality, ambient temperature and biotic as well as abiotic stresses. The key florigenic signal FLOWERING LOCUS T (FT) is regulated by several flowering activators, such as CONSTANS (CO), and repressors, such as FLOWERING LOCUS C (FLC). Chromatin modifications are essential for regulated gene expression, which often involves the well conserved MULTICOPY SUPRESSOR OF IRA 1 (MSI1)-like protein family. MSI1-like proteins are ubiquitous partners of various complexes, such as POLYCOMB REPRESSIVE COMPLEX2 or CHROMATIN ASSEMBLY FACTOR 1. In Arabidopsis, one of the functions of MSI1 is to control the switch to flowering. Arabidopsis MSI1 is needed for the correct expression of the floral integrator gene SUPPRESSOR OF CO 1 (SOC1). Here, we show that the histone-binding protein MSI1 acts in the photoperiod pathway to regulate normal expression of CO in long day (LD) photoperiods. Reduced expression of CO in msi1-mutants leads to failure of FT and SOC1 activation and to delayed flowering. MSI1 is needed for normal sensitivity of Arabidopsis to photoperiod, because msi1-mutants responded less than wild type to an intermittent LD treatment of plants grown in short days. Finally, genetic analysis demonstrated that MSI1 acts upstream of the CO-FT pathway to enable an efficient photoperiodic response and to induce flowering.
An Arabidopsis blue-light receptor, Cry2, has been found to play a critical role in the photoperiodic control of flowering time; and genes have been identified that may control the production of a transmissible flower-inducing signal, which may turn out to be the long-elusive putative flowering hormone 'florigen'.
Lyons, Rebecca; Rusu, Anca; Stiller, Jiri; Powell, Jonathan; Manners, John M; Kazan, Kemal
Plants respond to pathogens either by investing more resources into immunity which is costly to development, or by accelerating reproductive processes such as flowering time to ensure reproduction occurs before the plant succumbs to disease. In this study we explored the link between flowering time and pathogen defense using the interaction between Arabidopsis thaliana and the root infecting fungal pathogen Fusarium oxysporum. We report that F. oxysporum infection accelerates flowering time and regulates transcription of a number of floral integrator genes, including FLOWERING LOCUS C (FLC), FLOWERING LOCUS T (FT) and GIGANTEA (GI). Furthermore, we observed a positive correlation between late flowering and resistance to F. oxysporum in A. thaliana natural ecotypes. Late-flowering gi and autonomous pathway mutants also exhibited enhanced resistance to F. oxysporum, supporting the association between flowering time and defense. However, epistasis analysis showed that accelerating flowering time by deletion of FLC in fve-3 or fpa-7 mutants did not alter disease resistance, suggesting that the effect of autonomous pathway on disease resistance occurs independently from flowering time. Indeed, RNA-seq analyses suggest that fve-3 mediated resistance to F. oxysporum is most likely a result of altered defense-associated gene transcription. Together, our results indicate that the association between flowering time and pathogen defense is complex and can involve both pleiotropic and direct effects.
Denay, Grégoire; Chahtane, Hicham; Tichtinsky, Gabrielle; Parcy, François
In Arabidopsis, floral meristems appear on the flanks of the inflorescence meristem. Their stereotypic development, ultimately producing the four whorls of floral organs, is essentially controlled by a network coordinating growth and cell-fate determination. This network integrates hormonal signals, transcriptional regulators, and mechanical constraints. Mechanisms regulating floral meristem formation have been studied at many different scales, from protein structure to tissue modeling. In this paper, we review recent findings related to the emergence of the floral meristem and floral fate determination and examine how this field has been impacted by recent technological developments. Copyright © 2016 Elsevier Ltd. All rights reserved.
Kirchoff, Bruce K; Lagomarsino, Laura P; Newman, Winnell H; Bartlett, Madelaine E; Specht, Chelsea D
We present new comparative data on early floral development of Heliconia latispatha, an ecologically and horticulturally important tropical plant within the order Zingiberales. Modification of the six members of two androecial whorls is characteristic of Zingiberales, with a reduction in number of fertile stamen from five or six in the banana families (Musaceae, Strelitziaceae, Lowiaceae, and Heliconiaceae) to one in Costaceae and Zingiberaceae and one-half in Marantaceae and Cannaceae. The remaining five infertile stamens in these later four families (the ginger families) are petaloid, and in Costaceae and Zingiberaceae fuse together to form a novel structure, the labellum. Within this developmental sequence, Heliconiaceae share with the ginger families the possession of an antisepalous staminode, a synapomorphy that has been used to place Heliconiaceae as sister to the ginger family clade. Here, we use epi-illumination light microscopy and reconstruction of serial sections to investigate the ontogeny of the Heliconia flower with emphasis on the ontogeny of the staminode. We compare floral development in Heliconia with that previously described for other species of Zingiberales. A comparison of floral structure and development across Zingiberales is presented to better understand the evolution of the flower in this charismatic group of tropical plants.
Levin, J Z; Fletcher, J C; Chen, X; Meyerowitz, E M
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.
Deyong Ren; Li Zhu; Zhenyu Gao; Guojun Dong; Guangheng Zhang; Longbiao Guo; Dali Zeng; and Qian Qian; Yuchun Rao; Liwen Wu; Qiankun Xu; Zizhuang Li; Haiping Yu; Yu Zhang; Yujia Leng; Jiang Hu
Moderate plant height and successful establish-ment of reproductive organs play pivotal roles in rice grain production. The molecular mechanism that controls the two aspects remains unclear in rice. In the present study, we characterized a rice gene, ABNORMAL FLOWER AND DWARF1 (AFD1) that determined plant height, floral development and grain yield. The afd1 mutant showed variable defects including the dwarfism, long panicle, low seed setting and reduced grain yield. In addition, abnormal floral organs were also observed in the afd1 mutant including slender and thick hulls, and hull-like lodicules. AFD1 encoded a DUF640 domain protein and was ex-pressed in all tested tissues and organs. Subcellular localization showed AFD1-green fluorescent fusion protein (GFP) was localized in the nucleus. Meantime, our results suggested that AFD1 regulated the expression of cell division and expansion related genes.
Ren, Deyong; Rao, Yuchun; Wu, Liwen; Xu, Qiankun; Li, Zizhuang; Yu, Haiping; Zhang, Yu; Leng, Yujia; Hu, Jiang; Zhu, Li; Gao, Zhenyu; Dong, Guojun; Zhang, Guangheng; Guo, Longbiao
Abstract Moderate plant height and successful establishment of reproductive organs play pivotal roles in rice grain production. The molecular mechanism that controls the two aspects remains unclear in rice. In the present study, we characterized a rice gene, ABNORMAL FLOWER AND DWARF1 (AFD1) that determined plant height, floral development and grain yield. The afd1 mutant showed variable defects including the dwarfism, long panicle, low seed setting and reduced grain yield. In addition, abnormal floral organs were also observed in the afd1 mutant including slender and thick hulls, and hull‐like lodicules. AFD1 encoded a DUF640 domain protein and was expressed in all tested tissues and organs. Subcellular localization showed AFD1‐green fluorescent fusion protein (GFP) was localized in the nucleus. Meantime, our results suggested that AFD1 regulated the expression of cell division and expansion related genes. PMID:26486996
Teor e composição do óleo essencial de inflorescências e folhas de Lavandula dentata L. em diferentes estádios de desenvolvimento floral e épocas de colheita Yield and composition of essential oil from inflorescences and leaves of lavender (Lavandula dentata L. in different flower development stages and harvest times
, cosmetic and personal care industries. The aim of this study was to evaluate the yield and composition of essential oil from lavender inflorescences and leaves in different development stages. The experimental design was completely randomized in 2 x 3 factorial arrangement, with three flower development stages (bud, pre-anthesis/anthesis and senescence and two harvest periods (January and April, and 5 replicates. The essential oil samples were obtained by hydrodistillation, and the compounds were analyzed by gas chromatography coupled to mass spectrometry (GC/MS. There was an interaction between the factors harvest time and flower development on essential oil yield of inflorescences, and a superior average was observed for flower buds harvested in January. The development stages did not alter the essential oil yield of leaves. The development stages influenced the levels of compounds of the essential oil from inflorescences and leaves. For essential oil in senescent flower stage harvested in April, there was a high level of 1,8-cineol, whereas in the remaining development stages, the levels were lower in both harvest times. The levels of camphor increased in the pre-anthesis/anthesis and senescence in January harvest. The essential oil from leaves presented higher levels of 1,8-cineol in branches with flowers in pre-anthesis/anthesis. Camphor and fenchone levels were higher in branches with buds. The essential oil from leaves of branches with buds and senescent flowers showed higher levels of linalool than that from inflorescences.
Coelho, Carla P; Minow, Mark A A; Chalfun-Júnior, Antonio; Colasanti, Joseph
Agriculturally important grasses such as rice, maize, and sugarcane are evolutionarily distant from Arabidopsis, yet some components of the floral induction process are highly conserved. Flowering in sugarcane is an important factor that negatively affects cane yield and reduces sugar/ethanol production from this important perennial bioenergy crop. Comparative studies have facilitated the identification and characterization of putative orthologs of key flowering time genes in sugarcane, a complex polyploid plant whose genome has yet to be sequenced completely. Using this approach we identified phosphatidylethanolamine-binding protein (PEBP) gene family members in sugarcane that are similar to the archetypical FT and TFL1 genes of Arabidopsis that play an essential role in controlling the transition from vegetative to reproductive growth. Expression analysis of ScTFL1, which falls into the TFL1-clade of floral repressors, showed transcripts in developing leaves surrounding the shoot apex but not at the apex itself. ScFT1 was detected in immature leaves and apical regions of vegetatively growing plants and, after the floral transition, expression also occurred in mature leaves. Ectopic over-expression of ScTFL1 in Arabidopsis caused delayed flowering in Arabidopsis, as might be expected for a gene related to TFL1. In addition, lines with the latest flowering phenotype exhibited aerial rosette formation. Unexpectedly, over-expression of ScFT1, which has greatest similarity to the florigen-encoding FT, also caused a delay in flowering. This preliminary analysis of divergent sugarcane FT and TFL1 gene family members from Saccharum spp. suggests that their expression patterns and roles in the floral transition has diverged from the predicted role of similar PEBP family members.
Carla P. Coelho
Full Text Available Agriculturally important grasses such as rice, maize and sugarcane are evolutionarily distant from Arabidopsis, yet some components of the floral induction process are highly conserved. Flowering in sugarcane is an important factor that negatively affects cane yield and reduces sugar/ethanol production from this important perennial bioenergy crop. Comparative studies have facilitated the identification and characterization of putative orthologs of key flowering time genes in sugarcane, a complex polyploid plant whose genome has yet to be sequenced completely. Using this approach we identified phosphatidylethanolamine-binding protein (PEBP gene family members in sugarcane that are similar to the archetypical FT and TFL1 genes of Arabidopsis that play an essential role in controlling the transition from vegetative to reproductive growth. Expression analysis of ScTFL1, which falls into the TFL1-clade of floral repressors, showed transcripts in developing leaves surrounding the shoot apex but not at the apex itself. ScFT1 was detected in immature leaves and apical regions of vegetatively growing plants and, after the floral transition, expression also occurred in mature leaves. Ectopic over-expression of ScTFL1 in Arabidopsis caused delayed flowering in Arabidopsis, as might be expected for a gene related to TFL1. In addition, lines with the latest flowering phenotype exhibited aerial rosette formation. Unexpectedly, over-expression of ScFT1, which has greatest similarity to the florigen-encoding FT, also caused a delay in flowering. This preliminary analysis of divergent sugarcane FT and TFL1 gene family members from Saccharum spp. suggests that their expression patterns and roles in the floral transition has diverged from the predicted role of similar PEBP family members.
Coelho, Carla P.; Minow, Mark A. A.; Chalfun-Júnior, Antonio; Colasanti, Joseph
Agriculturally important grasses such as rice, maize, and sugarcane are evolutionarily distant from Arabidopsis, yet some components of the floral induction process are highly conserved. Flowering in sugarcane is an important factor that negatively affects cane yield and reduces sugar/ethanol production from this important perennial bioenergy crop. Comparative studies have facilitated the identification and characterization of putative orthologs of key flowering time genes in sugarcane, a complex polyploid plant whose genome has yet to be sequenced completely. Using this approach we identified phosphatidylethanolamine-binding protein (PEBP) gene family members in sugarcane that are similar to the archetypical FT and TFL1 genes of Arabidopsis that play an essential role in controlling the transition from vegetative to reproductive growth. Expression analysis of ScTFL1, which falls into the TFL1-clade of floral repressors, showed transcripts in developing leaves surrounding the shoot apex but not at the apex itself. ScFT1 was detected in immature leaves and apical regions of vegetatively growing plants and, after the floral transition, expression also occurred in mature leaves. Ectopic over-expression of ScTFL1 in Arabidopsis caused delayed flowering in Arabidopsis, as might be expected for a gene related to TFL1. In addition, lines with the latest flowering phenotype exhibited aerial rosette formation. Unexpectedly, over-expression of ScFT1, which has greatest similarity to the florigen-encoding FT, also caused a delay in flowering. This preliminary analysis of divergent sugarcane FT and TFL1 gene family members from Saccharum spp. suggests that their expression patterns and roles in the floral transition has diverged from the predicted role of similar PEBP family members. PMID:24904616
Malgorzata A Domagalska
Full Text Available BACKGROUND: Genetic interactions between phytohormones in the control of flowering time in Arabidopsis thaliana have not been extensively studied. Three phytohormones have been individually connected to the floral-timing program. The inductive function of gibberellins (GAs is the most documented. Abscisic acid (ABA has been demonstrated to delay flowering. Finally, the promotive role of brassinosteroids (BRs has been established. It has been reported that for many physiological processes, hormone pathways interact to ensure an appropriate biological response. METHODOLOGY: We tested possible genetic interactions between GA-, ABA-, and BR-dependent pathways in the control of the transition to flowering. For this, single and double mutants deficient in the biosynthesis of GAs, ABA, and BRs were used to assess the effect of hormone deficiency on the timing of floral transition. Also, plants that over-express genes encoding rate-limiting enzymes in each biosynthetic pathway were generated and the flowering time of these lines was investigated. CONCLUSIONS: Loss-of-function studies revealed a complex relationship between GAs and ABA, and between ABA and BRs, and suggested a cross-regulatory relation between GAs to BRs. Gain-of-function studies revealed that GAs were clearly limiting in their sufficiency of action, whereas increases in BRs and ABA led to a more modest phenotypic effect on floral timing. We conclude from our genetic tests that the effects of GA, ABA, and BR on timing of floral induction are only in partially coordinated action.
Mourik, van S.; Kaufmann, K.; Dijk, van A.D.J.; Angenent, G.C.; Merks, R.M.H.; Molenaar, J.
Spatial organ arrangement plays an important role in flower development. The position and the identity of floral organs is influenced by various processes, in particular the expression of MADS-box transcription factors for identity and dynamics of the plant hormone auxin for positioning. We are curr
Luo, Xiao; Sun, Xiaoli; Liu, Baohui; Zhu, Dan; Bai, Xi; Cai, Hua; Ji, Wei; Cao, Lei; Wu, Jing; Wang, Mingchao; Ding, Xiaodong; Zhu, Yanming
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.
Full Text Available 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.
Li, Chao; Wang, Yan; Xu, Liang; Nie, Shanshan; Chen, Yinglong; Liang, Dongyi; Sun, Xiaochuan; Karanja, Benard K.; Luo, Xiaobo; Liu, Liwang
The MADS-box gene family is an important transcription factor (TF) family that is involved in various aspects of plant growth and development, especially flowering time and floral organogenesis. Although it has been reported in many plant species, the systematic identification and characterization of MADS-box TF family is still limited in radish (Raphanus sativus L.). In the present study, a comprehensive analysis of MADS-box genes was performed, and a total of 144 MADS-box family members were identified from the whole radish genome. Meanwhile, a detailed list of MADS-box genes from other 28 plant species was also investigated. Through the phylogenetic analysis between radish and Arabidopsis thaliana, all the RsMADS genes were classified into two groups including 68 type I (31 Mα, 12 Mβ and 25Mγ) and 76 type II (70 MIKCC and 6 MIKC∗). Among them, 41 (28.47%) RsMADS genes were located in nine linkage groups of radish from R1 to R9. Moreover, the homologous MADS-box gene pairs were identified among radish, A. thaliana, Chinese cabbage and rice. Additionally, the expression profiles of RsMADS genes were systematically investigated in different tissues and growth stages. Furthermore, quantitative real-time PCR analysis was employed to validate expression patterns of some crucial RsMADS genes. These results could provide a valuable resource to explore the potential functions of RsMADS genes in radish, and facilitate dissecting MADS-box gene-mediated molecular mechanisms underlying flowering and floral organogenesis in root vegetable crops. PMID:27703461
Full Text Available The MADS-box gene family is an important transcription factor (TF family that is involved in various aspects of plant growth and development, especially flowering time and floral organogenesis. Although it has been reported in many plant species, the systematic identification and characterization of MADS-box TF family is still limited in radish (Raphanus sativus L.. In the present study, a comprehensive analysis of MADS-box genes was performed, and a total of 144 MADS-box family members were identified from the whole radish genome. Meanwhile, a detailed list of MADS-box genes from other 28 plant species was also investigated. Through the phylogenetic analysis between radish and Arabidopsis thaliana, all the RsMADS genes were classified into two groups including 68 type I (31 Mα, 12 Mβ and 25Mγ and 76 type II (70 MIKCC and 6 MIKC*. Among them, 41 (28.47% RsMADS genes were located in nine linkage groups of radish from R1 to R9. Moreover, the homologous MADS-box gene pairs were identified among radish, A. thaliana, Chinese cabbage and rice. Additionally, the expression profiles of RsMADS genes were systematically investigated in different tissues and growth stages. Furthermore, quantitative real-time PCR analysis was employed to validate expression patterns of some crucial RsMADS genes. These results could provide a valuable resource to explore the potential functions of RsMADS genes in radish, and facilitate dissecting MADS-box gene-mediated molecular mechanisms underlying flowering and floral organogenesis in root vegetable crops.
Full Text Available O objetivo do estudo foi avaliar o efeito do local, cultivar e época em parâmetros físicos, morfológicos e fisiológicos de gemas florais de pereira e o possível envolvimento com a ocorrência de abortamento de gemas florais no Sul do Brasil. Para isso, conduziram-se dois experimentos durante o ano de 2000. Foram coletadas gemas florais de três cultivares (cvs., em três regiões no Sul do Brasil. Analisaram-se o volume, peso, comprimento e diâmetro de gema, peso seco de escamas, comprimento e peso seco da inflorescência, número de primórdios florais por gema e índice de necrose. Verificaram-se a ocorrência de duplicação de inflorescências e a formação de grande número de primórdios florais por gema nos locais onde os índices de abortamento foram maiores. As cvs. asiáticas apresentaram maior número de primórdios comparado à cv. Kieffer (híbrido. Na região de São Joaquim-SC, a pereira apresenta melhor adaptação, caracterizada por melhor formação da estrutura floral. As cvs. asiáticas, especialmente em Pelotas, apresentaram alterações em nível de primórdios florais, tais como: deformações, necrose de pistilo, abscisão, escurecimento de anteras e feixes vasculares. O comprimento da inflorescência permitiu diferenciar as cultivares, quanto à época de retomada do desenvolvimento floral final, sendo a cv. Kieffer mais precoce que as cvs. Nijisseiki e Housui.The objective of this study was to evaluate the effect of location, cultivar and time on the physical, morphological and physiological characteristics of pear flower bud, and possible envolvement with flower bud abortion, in the Southern of Brazil. Two experiments were conducted in the year 2000, in three locations and three cultivars. Volume, weight, length and bud diameter, dry weight of scales, inflorescence length, number of flower primordia per bud, inflorescence dry weight and internal necrosis degree of buds were evaluated. The occurrence of
Full Text Available Phalaenopsis is one of the world’s most popular and important epiphytic monopodial orchids. The extraordinary floral diversity of Phalaenopsis is a reflection of its evolutionary success. As a consequence of this diversity, and of the complexity of flower color development in Phalaenopsis, this species is a valuable research material for developmental biology studies. Nevertheless, research on the molecular mechanisms underlying flower color and floral organ formation in Phalaenopsis is still in the early phases. In this study, we generated large amounts of data from Phalaenopsis flowers by combining Illumina sequencing with differentially expressed gene (DEG analysis. We obtained 37 723 and 34 020 unigenes from petals and labella, respectively. A total of 2736 DEGs were identified, and the functions of many DEGs were annotated by BLAST-searching against several public databases. We mapped 837 up-regulated DEGs (432 from petals and 405 from labella to 102 Kyoto Encyclopedia of Genes and Genomes pathways. Almost all pathways were represented in both petals (102 pathways and labella (99 pathways. DEGs involved in energy metabolism were significantly differentially distributed between labella and petals, and various DEGs related to flower color and floral differentiation were found in the two organs. Interestingly, we also identified genes encoding several key enzymes involved in carotenoid synthesis. These genes were differentially expressed between petals and labella, suggesting that carotenoids may influence Phalaenopsis flower color. We thus conclude that a combination of anthocyanins and/or carotenoids determine flower color formation in Phalaenopsis. These results broaden our understanding of the mechanisms controlling flower color and floral organ differentiation in Phalaenopsis and other orchids.
Jensen, C.S.; Salchert, K.; Nielsen, K.K.
. To investigate the regulation of meristem identity and the control of floral transition in perennial ryegrass (Lolium perenne) we isolated a ryegrass TERMINAL FLOWER1-like gene, LpTFL1, and characterized it for its function in ryegrass flower development. Perennial ryegrass requires a cold treatment of at least...... spikelets. Arabidopsis plants overexpressing LpTFL1 were significantly delayed in flowering and exhibited dramatic changes in architecture such as extensive lateral branching, increased growth of all vegetative organs, and a highly increased trichome production. Furthermore, overexpression of LpTFL1...... and a controller of axillary meristem identity in ryegrass....
Víctor Manuel Pardo Cardona
Full Text Available Treinta especies de Uredinales (royas se han registrado en Colombia parasitando a veintiseis especies de plantas cultivadas de interés floral comprendidas en 21 géneros y 15 familias botánicas. Se registra para Colombia y la zona andina de Sudamérica a Puccinia hemerocallidis Thuemen. Se confirma la presencia en Colombia de Puccinia antirrhini Dietel & Holway y Uromyces gladioli P. Hennings.Thirty species of Uredinales (rust fungi are registered in Colombia parasitizing 26 species of cultivated flowers belonging to 21 genera and 15 botanical families. Puccinia hemerocallidis Thuemen is a new record for Colombia and the Andean zone of South America. Puccinia antirrhini Dietel & Holway and Uromyces gladioli P. Hennings are first records for Colombia.
Full Text Available Timing of flowering is a reproductive trait that has significant impact on fitness in plants. In contrast to recent advances in understanding the molecular basis of floral transition, few empirical studies have addressed questions concerning population processes of flowering time diversification within species. We analyzed chloroplast DNA genealogical structure of flowering time variation in central Eurasian wild wheat Aegilops tauschii Coss. using 200 accessions that represent the entire species range. Flowering time measured as days from germination to flowering varied from 144.0 to 190.0 days (average 161.3 days among accessions in a common garden/greenhouse experiment. Subsequent genealogical and statistical analyses showed that (1 there exist significant longitudinal and latitudinal clines in flowering time at the species level, (2 the early-flowering phenotype evolved in two intraspecific lineages, (3 in Asia, winter temperature was an environmental factor that affected the longitudinal clinal pattern of flowering time variation, and (4 in Transcaucasus-Middle East, some latitudinal factors affected the geographic pattern of flowering time variation. On the basis of palaeoclimatic, biogeographic, and genetic evidence, the northern part of current species' range [which was within the temperate desert vegetation (TDV zone at the Last Glacial Maximum] is hypothesized to have harbored species refugia. Postglacial southward dispersal from the TDV zone seems to have been driven by lineages that evolved short-flowering-time phenotypes through different genetic mechanisms in Transcaucasus-Middle East and Asia.
Full Text Available The perianth of the double-flowered morph of Nigella damascena L. consists of spirally inserted petaloid sepals and sepal-like organs, similar in shape and colour to the petaloid sepals of the wild-type flower. It is devoid of petals. We compare the vascularization of each organ category of the double flower with that of the wild-type. We show that the vascular patterns of the sepal-like organs and of the petals are identical, and found an inverse relationship between the number of bracts and the number of sepals in the double-flowered morph. These two surprising findings will influence the future evo-devo studies on this plant model.
Vallejo-Marín, M; Manson, J S; Thomson, J D; Barrett, S C H
In many nectarless flowering plants, pollen serves as both the carrier of male gametes and as food for pollinators. This can generate an evolutionary conflict if the use of pollen as food by pollinators reduces the number of gametes available for cross-fertilization. Heteranthery, the production of two or more stamen types by individual flowers reduces this conflict by allowing different stamens to specialize in 'pollinating' and 'feeding' functions. We used experimental studies of Solanum rostratum (Solanaceae) and theoretical models to investigate this 'division of labour' hypothesis. Flight cage experiments with pollinating bumble bees (Bombus impatiens) demonstrated that although feeding anthers are preferentially manipulated by bees, pollinating anthers export more pollen to other flowers. Evolutionary stability analysis of a model of pollination by pollen consumers indicated that heteranthery evolves when bees consume more pollen than should optimally be exchanged for visitation services, particularly when pollinators adjust their visitation according to the amount of pollen collected.
The initiation of flowering is tightly regulated by the endogenous and environment signals, which is crucial for the reproductive success of flowering plants. It is well known that autonomous and vernalization pathways repress transcription of FLOWERING LOCUS C (FLC), a focal floral repressor, but how its protein stability is regulated remains largely unknown. Here, we found that mutations in a novel Arabidopsis SUMO protease 1 (ASP1) resulted in a strong late-flowering phenotype under long-days, but to a lesser extent under short-days. ASP1 localizes in the nucleus and exhibited a SUMO protease activity in vitro and in vivo. The conserved Cys-577 in ASP1 is critical for its enzymatic activity, as well as its physiological function in the regulation of flowering time. Genetic and gene expression analyses demonstrated that ASP1 promotes transcription of positive regulators of flowering, such as FT, SOC1 and FD, and may function in both CO-dependent photoperiod pathway and FLC-dependent pathways. Although the transcription level of FLC was not affected in the loss-of-function asp1 mutant, the protein stability of FLC was increased in the asp1 mutant. Taken together, this study identified a novel bona fide SUMO protease, ASP1, which positively regulates transition to flowering at least partly by repressing FLC protein stability.
Sun, Jing; Wang, Heng; Ren, Liping; Chen, Sumei; Chen, Fadi; Jiang, Jiafu
The chrysanthemum genome harbors three FT-like genes: CmFTL1 and CmFTL3 are thought to act as regulators of floral induction under long-day (LD) and short-day (SD) conditions, respectively, whereas the function of CmFTL2 is currently unclear. The objective of the present research was to explore the function of CmFTL2 in the determination of flowering time of the photo-insensitive chrysanthemum cultivar 'Floral Yuuka', both in response to variation in the photoperiod and to the exogenous provision of sucrose. Spraying leaves of 'Floral Yuuka' plants with 50 mM sucrose accelerated flowering and increased the level of CmFTL2 transcription in the leaf more strongly than either CmFTL1 or FTL3 under both long and SD conditions. Transcription profiling indicated that all three CmFTL genes were upregulated during floral induction. The relationship of the CmFTL2 sequence with that of other members of the PEBP family suggested that its product contributes to the florigen rather than to the anti-florigen complex. The heterologous expression of CmFTL2 in the Arabidopsis thaliana ft-10 mutant rescued the mutant phenotype, showing that CmFTL2 could compensate for the absence of FT. These results suggest that CmFTL2 acts as a regulator of floral transition and responds to both the photoperiod and sucrose.
Jun Hyung Lee; Paula M. Pijut
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...
Danilevskaya, Olga N; Meng, Xin; McGonigle, Brian; Muszynski, Michael G
The transition from vegetative to reproductive development is a critical turning point in a plant’s life cycle. It is now widely accepted that a leaf-borne signal, florigen, moves via the phloem from leaves to the shoot apical meristem to trigger its reprogramming to produce flowers. In part, the florigenic signal comprises a protein that belongs to the phosphatidylethanolamine-binding protein (PEBP) family that is present in all living organisms but displays diverse functions. The founding floral-promoting PEBP gene in Arabidopsis is FLOWERING LOCUS T (FT) whose functional homologs have been indentified in many flowering plants. We recently accumulated sufficient evidence to demonstrate the maize FT homolog ZCN8 has florigenic function. This task was particularly challenging due to the large number of FT-homologous genes in the maize genome. Here we show that ZCN8 function is more complex than simply regulating the floral transition. ZCN8 appears to play a pleiotropic role in the regulation of generalized growth of vegetative and reproductive tissues.
Song, Young Hun; Shim, Jae Sung; Kinmonth-Schultz, Hannah A; Imaizumi, Takato
Many plants use information about changing day length (photoperiod) to align their flowering time with seasonal changes to increase reproductive success. A mechanism for photoperiodic time measurement is present in leaves, and the day-length-specific induction of the FLOWERING LOCUS T (FT) gene, which encodes florigen, is a major final output of the pathway. Here, we summarize the current understanding of the molecular mechanisms by which photoperiodic information is perceived in order to trigger FT expression in Arabidopsis as well as in the primary cereals wheat, barley, and rice. In these plants, the differences in photoperiod are measured by interactions between circadian-clock-regulated components, such as CONSTANS (CO), and light signaling. The interactions happen under certain day-length conditions, as previously predicted by the external coincidence model. In these plants, the coincidence mechanisms are governed by multilayered regulation with numerous conserved as well as unique regulatory components, highlighting the breadth of photoperiodic regulation across plant species.
Ou, C-G; Mao, J-H; Liu, L-J; Li, C-J; Ren, H-F; Zhao, Z-W; Zhuang, F-Y
Carrot is generally regarded as a biennial plant with an obligatory vernalization requirement. Early spring cultivation makes plants vulnerable to premature bolting, which results in a loss of commercial value. However, our knowledge of flowering time genes and flowering mechanisms in carrot remain limited. Bolting behavior of D. carota ssp. carota 'Songzi', a wild species sensitive to flower induction by vernalization and photoperiod, and orange cultivar 'Amsterdam forcing', and their offspring were investigated in different growing conditions. We performed RNA-seq to identify the flowering time genes, and digital gene expression (DGE) analysis to examine their expression levels. The circadian patterns of related genes were identified by qPCR. The results showed bolting behavior of carrot was influenced by low temperature, illumination intensity and photoperiod. A total of 45 flowering time-related unigenes were identified, which were classified into five categories including photoperiod, vernalization, autonomous and gibberellin pathway, and floral integrators. Homologs of LATE ELONGATED HYPOCOTYL (LHY) and CONSTANS-LIKE 2 (COL2) were more highly expressed under short day condition than under long day condition. Homologs of COL2, CONSTANS-LIKE 5 (COL5), SUPPRESSION OF OVEREXPRESSION OF CONSTANS 1 (SOC1), FLOWERING LOCUS C (FLC) and GIBBERELLIC ACID INSENSITIVE (GAI) were differentially expressed between 'Songzi' and 'Amsterdam forcing'. The homolog of COL2 (Dct43207) was repressed by light, but that of COL5 (Dct20940) was induced. A preliminary model of genetic network controlling flowering time was constructed by associating the results of DGE analysis with correlation coefficients between genes. This study provides useful information for further investigating the genetic mechanism of flowering in carrot.
Pandey, Dhananjay K; Chaudhary, Bhupendra
Plant profilin genes encode core cell-wall structural proteins and are evidenced for their up-regulation under cotton domestication. Notwithstanding striking discoveries in the genetics of cell-wall organization in plants, little is explicit about the manner in which profilin-mediated molecular interplay and corresponding networks are altered, especially during cellular signalling of apical meristem determinacy and flower development. Here we show that the ectopic expression of GhPRF1 gene in tobacco resulted in the hyperactivation of apical meristem and early flowering phenotype with increased flower number in comparison to the control plants. Spatial expression alteration in CLV1, a key meristem-determinacy gene, is induced by the GhPRF1 overexpression in a WUS-dependent manner and mediates cell signalling to promote flowering. But no such expression alterations are recorded in the GhPRF1-RNAi lines. The GhPRF1 transduces key positive flowering regulator AP1 gene via coordinated expression of FT4, SOC1, FLC1 and FT1 genes involved in the apical-to-floral meristem signalling cascade which is consistent with our in silico profilin interaction data. Remarkably, these positive and negative flowering regulators are spatially controlled by the Actin-Related Protein (ARP) genes, specifically ARP4 and ARP6 in proximate association with profilins. This study provides a novel and systematic link between GhPRF1 gene expression and the flower primordium initiation via up-regulation of the ARP genes, and an insight into the functional characterization of GhPRF1 gene acting upstream to the flowering mechanism. Also, the transgenic plants expressing GhPRF1 gene show an increase in the plant height, internode length, leaf size and plant vigor. Overexpression of GhPRF1 gene induced early and increased flowering in tobacco with enhanced plant vigor. During apical meristem determinacy and flower development, the GhPRF1 gene directly influences key flowering regulators through ARP
Many plants synchronize their flowering times with changing seasons to maximize reproductive success. A key seasonal cue is the change in day length (photoperiod), that induces the production of a systemic flowering signaling molecule called florigen. A major florigen component is FLOWERING LOCUS T (FT) or its orthologs. In the long-day plant Arabidopsis thaliana, FT expression is well known to be activated by the photoperiod pathway output specifically near dusk in long days; however, underappreciated is the importance of FT silencing at other times of the day, in enabling Arabidopsis to respond only to long days in flowering. We have recently reported that a plant-specific chromatin-silencing complex called EMF1c represses FT expression at times other than around dusk in long days to prevent its temporal ectopic expression from "spoiling" the long-day floral induction in Arabidopsis. Here I further discuss in other day-length sensitive plants the potential involvement of a chromatin mechanism similar to the Arabidopsis EMF1c-mediated silencing, in repressing the expression of FT orthologs to enable diverse photoperiodic control of flowering.
Celesnik, Helena; Ali, Gul S; Robison, Faith M; Reddy, Anireddy S N
Transition to flowering in plants is tightly controlled by environmental cues, which regulate the photoperiod and vernalization pathways, and endogenous signals, which mediate the autonomous and gibberellin pathways. In this work, we investigated the role of two Zn(2+)-finger transcription factors, the paralogues AtVOZ1 and AtVOZ2, in Arabidopsis thaliana flowering. Single atvoz1-1 and atvoz2-1 mutants showed no significant phenotypes as compared to wild type. However, atvoz1-1 atvoz2-1 double mutant plants exhibited several phenotypes characteristic of flowering-time mutants. The double mutant displayed a severe delay in flowering, together with additional pleiotropic phenotypes. Late flowering correlated with elevated expression of FLOWERING LOCUS C (FLC), which encodes a potent floral repressor, and decreased expression of its target, the floral promoter FD. Vernalization rescued delayed flowering of atvoz1-1 atvoz2-1 and reversed elevated FLC levels. Accumulation of FLC transcripts in atvoz1-1 atvoz2-1 correlated with increased expression of several FLC activators, including components of the PAF1 and SWR1 chromatin-modifying complexes. Additionally, AtVOZs were shown to bind the promoter of MOS3/SAR3 and directly regulate expression of this nuclear pore protein, which is known to participate in the regulation of flowering time, suggesting that AtVOZs exert at least some of their flowering regulation by influencing the nuclear pore function. Complementation of atvoz1-1 atvoz2-1 with AtVOZ2 reversed all double mutant phenotypes, confirming that the observed morphological and molecular changes arise from the absence of functional AtVOZ proteins, and validating the functional redundancy between AtVOZ1 and AtVOZ2.
Jordano Dorval Tavares de Carvalho
Full Text Available ABSTRACT This paper presents a morphological analysis of the flower and floral trichomes of three rare species of Dyckia: Dyckia ibicuiensis, D. polyclada and D. racinae. Flowers at anthesis were collected from natural populations and subjected to morphometric and microscopic analysis. Among the most representative features for Dyckia are: morphometrics of individual floral parts; the general configuration of the androecium and gynoecium; the degree of fusion of the stigmatic lobes; the morphology of the ovules, especially in relation to the chalazal appendix; and the presence and constitution of peltate trichomes in the perianth, which exhibited a polymorphism not previously reported for Dyckia. The characters were effective at describing each species, proposing phylogenetic inferences and recognizing infrageneric groupings. We propose two species groups, which are consistent with previous hypotheses about the relationships among the species of the genus. The objective of this study was to provide floral morphological data useful for characterizing these three rare species, delimiting the genus and forming phylogenetic hypotheses.
Full Text Available Orobanche alsatica Kirschl. is a very rare perennial plant included in the Polish Red Data Book. The hosts of this European-West Asian parasite are representatives of the family Apiaceae, primarily from the genera Peucedanum and Seseli. The species prefers alkaline substrates and sun-exposed slopes and hills. In Poland, it occurs most frequently in xerothermic grasslands and xerothermic fringe. The morphology of O. alsatica flowers, with special emphasis on the structure of the nectaries, was studied using light microscopy and scanning electron microscopy (SEM. The analysed plants originated from the Lublin Upland. The flowers of the species are characterised by the presence of a double perianth. The sepals are richly glandular, free; the outer sepals are dark red and the inner ones are yellow-green. Fused petals (5 form a bilabiate, dirty yellow corolla with dark red secretory trichomes on the abaxial surface. The stamens (4 with long, white S-shaped filaments are attached at the base to the corolla. There are glandular and non-glandular trichomes at the basal part of the filaments. Brown, oval anthers are characterised by the presence of a beak-like apex. The upper pistil is composed of an oval ovary and an arched style with a bipartite, fleshy, yellow stigma bearing numerous papillae. The O. alsatica nectary is formed by the basal part of the ovary at the corolla tube base. The secretory gland is intensively yellow and asymmetrical – on one side of the ovary it is higher and forms different height and size 4-5 protuberances, while on the other side it is very low. Nectar is secreted through modified stomata located primarily in the central part of the nectary. Stomatal cells are surrounded by 6-8 other epidermal cells and are located below these. The stomata are very regularly (linearly arranged forming a ring across the apical part of the protuberances. The stomata function asynchronously, as evidenced by the presence of both open and
Niu, Lifang; Fu, Chunxiang; Lin, Hao; Wolabu, Tezera W; Wu, Yanqi; Wang, Zeng-Yu; Tadege, Million
Switchgrass (Panicum virgatum L.), a perennial warm season bunchgrass native to North America, has been a target in the U.S. as a renewable bioenergy crop because of its ability to produce moderate to high biomass yield on marginal soils. Delaying flowering can increase vegetative biomass production by allowing prolonged growth before switching to the reproductive phase. Despite the identification of flowering time as a biomass trait in switchgrass, the molecular regulatory factors involved in controlling floral transition are poorly understood. Here we identified PvFT1, PvAPL1-3 and PvSL1, 2 as key flowering regulators required from floral transition initiation to development of floral organs. PvFT1 expression in leaves is developmentally regulated peaking at the time of floral transition, and diurnally regulated with peak at approximately 2 h into the dark period. Ectopic expression of PvFT1 in Arabidopsis, Brachypodium and switchgrass led to extremely early flowering, and activation of FT downstream target genes, confirming that it is a strong activator of flowering in switchgrass. Ectopic expression of PvAPL1-3 and PvSL1, 2 in Arabidopsis also activated early flowering with distinct floral organ phenotypes. Our results suggest that switchgrass has conserved flowering pathway regulators similar to Arabidopsis and rice.
Torti, Stefano; Fornara, Fabio; Vincent, Coral; Andrés, Fernando; Nordström, Karl; Göbel, Ulrike; Knoll, Daniela; Schoof, Heiko; Coupland, George
Flowering of Arabidopsis thaliana is induced by exposure to long days (LDs). During this process, the shoot apical meristem is converted to an inflorescence meristem that forms flowers, and this transition is maintained even if plants are returned to short days (SDs). We show that exposure to five LDs is sufficient to commit the meristem of SD-grown plants to flower as if they were exposed to continuous LDs. The MADS box proteins SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 (SOC1) and FRUITFULL (FUL) play essential roles in this commitment process and in the induction of flowering downstream of the transmissible FLOWERING LOCUS T (FT) signal. We exploited laser microdissection and Solexa sequencing to identify 202 genes whose transcripts increase in the meristem during floral commitment. Expression of six of these transcripts was tested in different mutants, allowing them to be assigned to FT-dependent or FT-independent pathways. Most, but not all, of those dependent on FT and its paralog TWIN SISTER OF FT (TSF) also relied on SOC1 and FUL. However, this dependency on FT and TSF or SOC1 and FUL was often bypassed in the presence of the short vegetative phase mutation. FLOR1, which encodes a leucine-rich repeat protein, was induced in the early inflorescence meristem, and flor1 mutations delayed flowering. Our data contribute to the definition of LD-dependent pathways downstream and in parallel to FT.
Torti, Stefano; Fornara, Fabio; Vincent, Coral; Andrés, Fernando; Nordström, Karl; Göbel, Ulrike; Knoll, Daniela; Schoof, Heiko; Coupland, George
Flowering of Arabidopsis thaliana is induced by exposure to long days (LDs). During this process, the shoot apical meristem is converted to an inflorescence meristem that forms flowers, and this transition is maintained even if plants are returned to short days (SDs). We show that exposure to five LDs is sufficient to commit the meristem of SD-grown plants to flower as if they were exposed to continuous LDs. The MADS box proteins SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 (SOC1) and FRUITFULL (FUL) play essential roles in this commitment process and in the induction of flowering downstream of the transmissible FLOWERING LOCUS T (FT) signal. We exploited laser microdissection and Solexa sequencing to identify 202 genes whose transcripts increase in the meristem during floral commitment. Expression of six of these transcripts was tested in different mutants, allowing them to be assigned to FT-dependent or FT-independent pathways. Most, but not all, of those dependent on FT and its paralog TWIN SISTER OF FT (TSF) also relied on SOC1 and FUL. However, this dependency on FT and TSF or SOC1 and FUL was often bypassed in the presence of the short vegetative phase mutation. FLOR1, which encodes a leucine-rich repeat protein, was induced in the early inflorescence meristem, and flor1 mutations delayed flowering. Our data contribute to the definition of LD-dependent pathways downstream and in parallel to FT. PMID:22319055
Vijayraghavan, Usha; Prasad, Kalika; Meyerowitz, Elliot
A combination of environmental factors and endogenous cues trigger floral meristem. initiation on the flanks of the shoot meristem. A plethora of regulatory genes have been implicated in this process. They function either as activators or as repressors of floral initiation. This review describes the mode of their action in a regulatory network that ensures the correct temporal and spatial control of floral meristem specification, its maintenance and determinate development.
Liu, Yongping; Yang, Jing; Yang, Mingfeng
Flowering, the floral transition from vegetative growth to reproductive growth, is induced by diverse endogenous and exogenous cues, such as photoperiod, temperature, hormones and age. Precise flowering time is critical to plant growth and evolution of species. The numerous renewal molecular and genetic results have revealed five flowering time pathways, including classical photoperiod pathway, vernalization pathway, autonomous pathway, gibberellins (GA) pathway and newly identified age pathway. These pathways take on relatively independent role, and involve extensive crosstalks and feedback loops. This review describes the complicated regulatory network of this floral transition to understand the molecular mechanism of flowering and provide references for further research in more plants.
He, Chaoying; Tian, Ying; Saedler, Rainer; Efremova, Nadia; Riss, Simone; Khan, Muhammad Ramzan; Yephremov, Alexander; Saedler, Heinz
Floral and vegetative development of plants is dependent on the combinatorial action of MADS-domain transcription factors. Members of the STMADS11 subclade, such as MPF1 of Physalis, are abundantly expressed in leaves as well as in floral organs, but their function is not yet clear. Our studies with transgenic Arabidopsis that over-express MPF1 suggest that MPF1 interacts with SOC1 to determine flowering time. However, MPF1 RNAi-mediated knockdown Physalis plants revealed a complex phenotype with changes in flowering time, plant architecture and seed size. Flowering of these plants was delayed by about 20% as compared to wild type. Expression of PFLFY is upregulated in the MPF1 RNAi lines, while PFFT and MPF3 genes are strongly repressed. MPF1 interacts with a subset of MADS-domain factors, namely with PFSOC1 in planta, and with PFSEP3 and PFFUL in yeast, supporting a regulatory role for this protein in flowering. The average size of seeds produced by the transgenic MPF1 RNAi plants is increased almost twofold. The height of these plants is also increased about twofold, but most axillary buds are stunted when compared to controls. Taken together, this suggests that members of the STMADS11 subclade act as positive regulators of flowering but have diverse functions in plant growth.
Fiil, Alice; Lenk, Ingo; Petersen, Klaus
Optimization of flowering is an important breeding goal in forage and turf grasses, such as perennial ryegrass (Lolium perenne L.). Nine floral control genes including Lolium perenne CONSTANS (LpCO), SISTER OF FLOWERING LOCUS T (LpSFT), TERMINAL FLOWER1 (LpTFL1), VERNALIZATION1 (LpVRN1, identical......, one single nucleotide polymorphism (SNP) was present per 127 bp between two randomly sampled sequences for the nine genes (π = 0.00790). Two MADS-box genes, LpMADS1 and LpMADS10, involved in timing of flowering showed high nucleotide diversity and rapid LD decay, whereas MADS-box genes involved...
Yasui, Yukiko; Tanaka, Wakana; Sakamoto, Tomoaki; Kurata, Tetsuya; Hirano, Hiro-Yuki
Meristems such as the shoot apical meristem and flower meristem (FM) act as a reservoir of stem cells, which reproduce themselves and supply daughter cells for the differentiation of lateral organs. In Oryza sativa (rice), the FLORAL ORGAN NUMBER2 (FON2) gene, which is similar to Arabidopsis CLAVATA3, is involved in meristem maintenance. In fon2 mutants, the numbers of floral organs are increased due to an enlargement of the FM. To identify new factors regulating meristem maintenance in rice, we performed a genetic screening of mutants that enhanced the fon2 mutation, and found a mutant line (2B-424) in which pistil number was dramatically increased. By using a map-based approach and next-generation sequencing, we found that the line 2B-424 had a complete loss-of-function mutation (a large deletion) in OsMADS3, a class C MADS-box gene that is known to be involved in stamen specification. Disruption of OsMADS3 in the fon2 mutant by CRISPR-Cas9 (clustered regularly interspaced short palindromic repeats-CRISPR-associated protein 9) technology caused a flower phenotype similar to that of 2B-424, confirming that the gene responsible for enhancement of fon2 was OsMADS3. Morphological analysis showed that the fon2 and osmads3 mutations synergistically affected pistil development and FM determinacy. We also found that whorl 3 was duplicated in mature flowers and the FM was enlarged at an early developmental stage in severe osmads3 single mutants. These findings suggest that OsMADS3 is involved not only in FM determinacy in late flower development but also in FM activity in early flower development. © The Author 2017. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: firstname.lastname@example.org.
Full Text Available Extensive studies on floral transition in model species have revealed a network of regulatory interactions between proteins that transduce and integrate developmental and environmental signals to promote or inhibit the transition to flowering. Previous studies indicated FLOWERING PROMOTING FACTOR 1 (FPF1 gene was involved in the promotion of flowering, but the molecular mechanism was still unclear. Here, FPF1 homologous sequences were screened from diploid Gossypium raimondii L. (D-genome, n = 13 and Gossypium arboreum L. genome (A-genome, n = 13 databases. Orthologous genes from the two species were compared, suggesting that distinctions at nucleic acid and amino acid levels were not equivalent because of codon degeneracy. Six FPF1 homologous genes were identified from the cultivated allotetraploid Gossypium hirsutum L. (AD-genome, n = 26. Analysis of relative transcripts of the six genes in different tissues revealed that this gene family displayed strong tissue-specific expression. GhFPF1, encoding a 12.0-kDa protein (Accession No: KC832319 exerted more transcripts in floral apices of short-season cotton, hinting that it could be involved in floral regulation. Significantly activated APETALA 1 and suppressed FLOWERING LOCUS C expression were induced by over-expression of GhFPF1 in the Arabidopsis Columbia-0 ecotype. In addition, transgenic Arabidopsis displayed a constitutive shade-avoiding phenotype that is characterized by long hypocotyls and petioles, reduced chlorophyll content, and early flowering. We propose that GhFPF1 may be involved in flowering time control and shade-avoidance responses.
Full Text Available In Arabidopsis, floral stem cells are maintained only at the initial stages of flower development, and they are terminated at a specific time to ensure proper development of the reproductive organs. Floral stem cell termination is a dynamic and multi-step process involving many transcription factors, chromatin remodeling factors and signaling pathways. In this review, we discuss the mechanisms involved in floral stem cell maintenance and termination, highlighting the interplay between transcriptional regulation and epigenetic machinery in the control of specific floral developmental genes. In addition, we discuss additional factors involved in floral stem cell regulation, with the goal of untangling the complexity of the floral stem cell regulatory network.
Iara Alvarenga Mesquita Pereira
Full Text Available A produção do estímulo floral (indução e emissão das primeiras sépalas, na gema floralmente determinada (evocação floral em Citrus sinensis (L. Osbeck cv. Pêra Rio pôde ser acompanhada pelas variações anatômicas nos meristemas apicais e axilares. Com objetivo de determinar a época na qual ocorre a indução e evocação floral, cortes longitudinais de gemas apicais e axilares, corados com pironina Y-methylgreen foram efetuados em períodos regulares de maio a agosto. Através das mudanças no formato da gema, principalmente diâmetro, que aumentou com a indução, foi possível determinar a época do ano na qual gemas vegetativas são induzidas a florescerem. Foram detectadas variações nos diâmetros das gemas no período de início da morfogênese floral (meados até o final de julho. A medição do diâmetro das gemas mostra-se um procedimento eficiente para acompanhar os fenômenos decorrentes da indução, evocação e morfogênese florais. Gemas vegetativas apresentam diâmetro médio de 100µm, com túnica composta por três camadas, de formato cônico, recobrindo o corpo, ao passo que a reprodutiva é mais achatada, após a iniciação do primeiro primórdio de sépala, exibindo diâmetro médio de 200µm. Coloração com pironina Y-methylgreen proporciona a captação do fenômeno da evocação floral, pela detecção de regiões mais concentradas em RNA, nas zonas periféricas das gemas; alteração bioquímica esta que precede a emissão das sépalas.The research aims to determine the time in which the inflorescence induction and evocation occurs. The production of inflorescence stimulus (induction and emission of first sepals in a bud determined as a flower bud (floral evocation in Citrus sinensis (L. Osbeck cv. Pêra Rio could be observed through the anatomic variations of the apical and lateral meristems. Longitudinal sections, stained with pironina Y-methylgreen were done in regular periods from May to August. The
Full Text Available Because of the long and unpredictable flowering period in bamboo, the molecular mechanism of bamboo flowering is unclear. Recent study showed that Arabidopsis PIN1-type parvulin 1 (Pin1At is an important floral activator and regulates floral transition by facilitating the cis/trans isomerization of the phosphorylated Ser/Thr residues preceding proline motifs in suppressor of overexpression of CO 1 (SOC1 and agamous-like 24 (AGL24. Whether bamboo has a Pin1 homolog and whether it works in bamboo flowering are still unknown. In this study, we cloned PvPin1, a homolog of Pin1At, from Phyllostachys violascens (Bambusoideae. Bioinformatics analysis showed that PvPin1 is closely related to Pin1-like proteins in monocots. PvPin1 was widely expressed in all tested bamboo tissues, with the highest expression in young leaf and lowest in floral bud. Moreover, PvPin1 expression was high in leaves before bamboo flowering then declined during flower development. Overexpression of PvPin1 significantly delayed flowering time by downregulating SOC1 and AGL24 expression in Arabidopsis under greenhouse conditions and conferred a significantly late flowering phenotype by upregulating OsMADS56 in rice under field conditions. PvPin1 showed subcellular localization in both the nucleus and cytolemma. The 1500-bp sequence of the PvPin1 promoter was cloned, and cis-acting element prediction showed that ABRE and TGACG-motif elements, which responded to abscisic acid (ABA and methyl jasmonate (MeJA, respectively, were characteristic of P. violascens in comparison with Arabidopsis. On promoter activity analysis, exogenous ABA and MeJA could significantly inhibit PvPin1 expression. These findings suggested that PvPin1 may be a repressor in flowering, and its delay of flowering time could be regulated by ABA and MeJA in bamboo.
Full Text Available The developmental transition from a vegetative to a reproductive phase (i.e., flowering is timed by the seasonal cue day length or photoperiod in many plant species. Through the photoperiod pathway, inductive day lengths trigger the production of a systemic flowering signal, florigen, to provoke the floral transition. FLOWERING LOCUS T (FT, widely conserved in angiosperms, is a major component of the mobile florigen. In the long-day plant Arabidopsis, FT expression is rhythmically activated by the output of the photoperiod pathway CONSTANS (CO, specifically at the end of long days. How FT expression is modulated at an adequate level in response to the long-day cue to set a proper flowering time remains unknown. Here, we report a periodic histone deacetylation mechanism for the photoperiodic modulation of FT expression. We have identified a plant-unique core structural component of an Arabidopsis histone deacetylase (HDAC complex. In long days, this component accumulates at dusk, and is recruited by a MADS-domain transcription factor to the FT locus specifically at the end of the day, leading to periodic histone deacetylation of FT chromatin at dusk. Furthermore, we found that at the end of long days CO activity not only activates FT expression but also enables HDAC-activity recruitment to FT chromatin to dampen the level of FT expression, and so prevent precocious flowering in response to the inductive long-day cue. These results collectively reveal a periodic histone deacetylation mechanism for the day-length control of flowering time in higher plants.
Gu, Xiaofeng; Wang, Yizhong; He, Yuehui
The developmental transition from a vegetative to a reproductive phase (i.e., flowering) is timed by the seasonal cue day length or photoperiod in many plant species. Through the photoperiod pathway, inductive day lengths trigger the production of a systemic flowering signal, florigen, to provoke the floral transition. FLOWERING LOCUS T (FT), widely conserved in angiosperms, is a major component of the mobile florigen. In the long-day plant Arabidopsis, FT expression is rhythmically activated by the output of the photoperiod pathway CONSTANS (CO), specifically at the end of long days. How FT expression is modulated at an adequate level in response to the long-day cue to set a proper flowering time remains unknown. Here, we report a periodic histone deacetylation mechanism for the photoperiodic modulation of FT expression. We have identified a plant-unique core structural component of an Arabidopsis histone deacetylase (HDAC) complex. In long days, this component accumulates at dusk, and is recruited by a MADS-domain transcription factor to the FT locus specifically at the end of the day, leading to periodic histone deacetylation of FT chromatin at dusk. Furthermore, we found that at the end of long days CO activity not only activates FT expression but also enables HDAC-activity recruitment to FT chromatin to dampen the level of FT expression, and so prevent precocious flowering in response to the inductive long-day cue. These results collectively reveal a periodic histone deacetylation mechanism for the day-length control of flowering time in higher plants.
Yan-Fei Zeng; Wei-Ning Bai; Yu Zhou; Da-Yong Zhang
In hermaphroditic plants, female reproductive success often varies among different positions within an inflorescence.However, few studies have evaluated the relative importance of underlying causes such as pollen limitation, resource limitation or architectural effect, and few have compared male allocation. During a 2-year investigation, we found that female reproductive success of an acropetally flowering species, Corydalis remota Fisch. ex Maxim. var. Iineariloba Maxim. was significantly lower in the upper late developing flowers when compared with the lower early flowers. Supplementation with outcross pollen did not improve female reproductive success of the upper flowers, while removal of the lower developing fruits significantly increased female reproductive success of the upper flowers in both years, evidencing resource limitation of the upper flowers. Female production in upper flowers was greatly improved by simultaneous pollen supplementation of the upper flowers and removal of the lower fruits, suggesting that, when resources are abundant, pollen may limit the female reproductive success of the upper flowers. The less seed mass in the upper flowers didn't increase in all treatments due to architecture. In the upper flowers, ovule production was significantly lower and the pollen : ovule ratio was significantly higher. These results suggest that male-biased sex allocation in the upper flowers may lead to increased male reproductive success, whereas the lower flowers have higher female reproductive success.
Concepción Gómez-Mena; Manuel Piñeiro; José M. Franco-Zorrilla; Julio Salinas; George Coupland; José M. Martínez-Zapater
.... Some of these signals promote the onset of flowering, whereas others repress it. We describe here the isolation and characterization of two allelic mutations that cause early flowering and define a new locus, EARLY BOLTING IN SHORT DAYS (EBS...
Kalivas, Apostolos; Pasentsis, Konstantinos; Polidoros, Alexios N; Tsaftaris, Athanasios S
For uncovering and understanding the molecular mechanisms controlling flower development in cultivated Crocus sativus and particularly the transformation of sepals in outer whorl (whorl 1) tepals, we have cloned and characterized the expression of a family of five PISTILLATA/GLOBOSA-like (PI/GLO-like) MADS-box genes expressed in the C. sativus flower. The deduced amino acid sequences of the coded proteins indicated high homology with members of the MADS-box family of transcription factors, and particularly with other members of the PI/GLO family of MADS-box proteins that control floral organ identity. PI/GLO expression studies in cultivated C. sativus uncover the presence of PI/GLO transcripts not only in the second and third whorls of flower organs as expected, but also in the outer whorl tepals that are the sepals in most typical flowers. This heterotopic expression of both B-class genes: PI/GLO and AP3/DEF, known to form heterodimers for stamens and petals (petaloid inner whor l-whorl 2-tepals in C. sativus), explains the homeotic transformation of sepals into outer whorl tepals in this species. Analysis of PI/GLO sequences from C. sativus for putative targets to known micro-RNAs (miRNAs) showed that the target site for ath-miRNA167 found in Arabidopsis thaliana PI is not present in C. sativus, however, the PI/GLO sequences may be regulated by an ath-miRNA163.
Lulu Tang; Bing Han
Complete understanding of floral function requires the recognition of floral traits at two aspects: floral design and floral display. Floral display, the fundamental unit of plant mating, refers to the number, type and arrangement of the open flowers on the plant in a certain period. Interactions between the flowers on a plant could influence pollinator behaviors on the plant and consequently may govern the mating outcomes. Pollinators prefer large floral displays, which often receive more vi...
Serrano-Mislata, Antonio; Fernández-Nohales, Pedro; Doménech, María J; Hanzawa, Yoshie; Bradley, Desmond; Madueño, Francisco
TERMINAL FLOWER 1 (TFL1) is a key regulator of Arabidopsis plant architecture that responds to developmental and environmental signals to control flowering time and the fate of shoot meristems. TFL1 expression is dynamic, being found in all shoot meristems, but not in floral meristems, with the level and distribution changing throughout development. Using a variety of experimental approaches we have analysed the TFL1 promoter to elucidate its functional structure. TFL1 expression is based on distinct cis-regulatory regions, the most important being located 3' of the coding sequence. Our results indicate that TFL1 expression in the shoot apical versus lateral inflorescence meristems is controlled through distinct cis-regulatory elements, suggesting that different signals control expression in these meristem types. Moreover, we identified a cis-regulatory region necessary for TFL1 expression in the vegetative shoot and required for a wild-type flowering time, supporting that TFL1 expression in the vegetative meristem controls flowering time. Our study provides a model for the functional organisation of TFL1 cis-regulatory regions, contributing to our understanding of how developmental pathways are integrated at the genomic level of a key regulator to control plant architecture. © 2016. Published by The Company of Biologists Ltd.
Pabón-Mora, Natalia; Ambrose, Barbara A; Litt, Amy
Several MADS box gene lineages involved in flower development have undergone duplications that correlate with the diversification of large groups of flowering plants. In the APETALA1 gene lineage, a major duplication coincides with the origin of the core eudicots, resulting in the euFUL and the euAP1 clades. Arabidopsis FRUITFULL (FUL) and APETALA1 (AP1) function redundantly in specifying floral meristem identity but function independently in sepal and petal identity (AP1) and in proper fruit development and determinacy (FUL). Many of these functions are largely conserved in other core eudicot euAP1 and euFUL genes, but notably, the role of APETALA1 as an "A-function" (sepal and petal identity) gene is thought to be Brassicaceae specific. Understanding how functional divergence of the core eudicot duplicates occurred requires a careful examination of the function of preduplication (FUL-like) genes. Using virus-induced gene silencing, we show that FUL-like genes in opium poppy (Papaver somniferum) and California poppy (Eschscholzia californica) function in axillary meristem growth and in floral meristem and sepal identity and that they also play a key role in fruit development. Interestingly, in opium poppy, these genes also control flowering time and petal identity, suggesting that AP1/FUL homologs might have been independently recruited in petal identity. Because the FUL-like gene functional repertoire encompasses all roles previously described for the core eudicot euAP1 and euFUL genes, we postulate subfunctionalization as the functional outcome after the major AP1/FUL gene lineage duplication event.
Zhang, Tiejun; Chao, Yuehui; Kang, Junmei; Ding, Wang; Yang, Qingchuan
Genes that regulate flowering time play crucial roles in plant development and biomass formation. Based on the cDNA sequence of Medicago truncatula (accession no. AY690425), the LFY gene of alfalfa was cloned. Sequence similarity analysis revealed high homology with FLO/LFY family genes of other plants. When fused to the green fluorescent protein, MsLFY protein was localized in the nucleus of onion (Allium cepa L.) epidermal cells. The RT-qPCR analysis of MsLFY expression patterns showed that the expression of MsLFY gene was at a low level in roots, stems, leaves and pods, and the expression level in floral buds was the highest. The expression of MsLFY was induced by GA3 and long photoperiod. Plant expression vector was constructed and transformed into Arabidopsis by the agrobacterium-mediated methods. PCR amplification with the transgenic Arabidopsis genome DNA indicated that MsLFY gene had integrated in Arabidopsis genome. Overexpression of MsLFY specifically caused early flowering under long day conditions compared with non-transgenic plants. These results indicated MsLFY played roles in promoting flowering time.
Marcelo Carnier Dornelas
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.
Peñuelas, Josep; Farré-Armengol, Gerard; Llusia, Joan; Gargallo-Garriga, Albert; Rico, Laura; Sardans, Jordi; Terradas, Jaume; Filella, Iolanda
The emission of floral terpenes plays a key role in pollination in many plant species. We hypothesized that the floral phyllospheric microbiota could significantly influence these floral terpene emissions because microorganisms also produce and emit terpenes. We tested this hypothesis by analyzing the effect of removing the microbiota from flowers. We fumigated Sambucus nigra L. plants, including their flowers, with a combination of three broad-spectrum antibiotics and measured the floral emissions and tissular concentrations in both antibiotic-fumigated and non-fumigated plants. Floral terpene emissions decreased by ca. two thirds after fumigation. The concentration of terpenes in floral tissues did not decrease, and floral respiration rates did not change, indicating an absence of damage to the floral tissues. The suppression of the phyllospheric microbial communities also changed the composition and proportion of terpenes in the volatile blend. One week after fumigation, the flowers were not emitting β-ocimene, linalool, epoxylinalool, and linalool oxide. These results show a key role of the floral phyllospheric microbiota in the quantity and quality of floral terpene emissions and therefore a possible key role in pollination.
Kudo, Gaku; Ishii, Hiroshi S; Hirabayashi, Yuimi; Ida, Takashi Y
Floral color change has been recognized as a pollination strategy, but its relative effectiveness has been evaluated insufficiently with respect to other floral traits. In this study, effects of floral color change on the visitation pattern of bumblebees were empirically assessed using artificial flowers. Four inflorescence types were postulated as strategies of flowering behavior: type 1 has no retention of old flowers, resulting in a small display size; type 2 retains old flowers without nectar production; type 3 retains old flowers with nectar; and type 4 retains color-changed old flowers without nectar. Effects of these treatments varied depending on both the total display size (single versus multiple inflorescences) and the pattern of flower-opening. In the single inflorescence experiment, a large floral display due to the retention of old flowers (types 2-4) enhanced pollinator attraction, and the number of flower visits per stay decreased with color change (type 4), suggesting a decrease in geitonogamous pollination. Type-4 plants also reduced the foraging time of bees in comparison with type-2 plants. In the multiple inflorescence experiment, the retention of old flowers did not contribute to pollinator attraction. When flowering occurred sequentially within inflorescences, type-4 plants successfully decreased the number of visits and the foraging time in comparison with type-2 plants. In contrast, floral color change did not influence the number of visits, and it extended the foraging time when flowering occurred simultaneously within inflorescences but the opening of inflorescences progressed sequentially within a plant. Therefore, the effectiveness of floral color change is highly susceptible to the display size and flowering pattern within plants, and this may limit the versatility of the color change strategy in nature.
Nilma Oliveira Dias
Full Text Available O presente estudo foi desenvolvido com o objetivo de avaliar a incidência e a severidade da malformação floral em diferentes cultivares de mangueira (Mangifera indica L., em condições de clima semi-árido, no município de Santa Maria da Vitória, Estado da Bahia. O experimento foi conduzido no mês de julho de 2001, em um cultivo comercial formado por diversas cultivares divididas em talhões. Os tratamentos foram compostos por seis cultivares assim distribuídas: T1- Rosa; T2- Haden; T3- Bourbon; T4- Palmer; T5- Tommy Atkins; T6-Van Dyke. Nas condições em que o trabalho foi desenvolvido, os menores índices de incidência e severidade da malformação floral foram obtidos pela cultivar Rosa que não apresentou sintomas, seguida pela 'Bourbon'. A cultivar Haden apresentou os maiores índices da doença.The present work was developed with the objective to evaluate the incidence and the severity of mango flower malformation in different cultivars, in conditions of semi-arid region, in Santa Maria da Vitória, Bahia State, Brazil. The experiment was carried out in july, 2001, in a mango orchard composed of different cultivars. The used treatments cultivars were: T1- Rosa; T2- Haden; T3 Bourbon; T4- Palmer; T5- Tommy Atkins; T6- Van Dyke. In the conditions that this work was carried out, the highest percentage of incidence and severity of flower malformation was gotten by Haden variety. Rosa and Bourbon cultivars presented minimum occurrence of the disease.
Full Text Available In rice (Oryza sativa L., there is a diversity in flowering time that is strictly genetically regulated. Some indica cultivars show extremely late flowering under long-day conditions, but little is known about the gene(s involved. Here, we demonstrate that functional defects in the florigen gene RFT1 are the main cause of late flowering in an indica cultivar, Nona Bokra. Mapping and complementation studies revealed that sequence polymorphisms in the RFT1 regulatory and coding regions are likely to cause late flowering under long-day conditions. We detected polymorphisms in the promoter region that lead to reduced expression levels of RFT1. We also identified an amino acid substitution (E105K that leads to a functional defect in Nona Bokra RFT1. Sequencing of the RFT1 region in rice accessions from a global collection showed that the E105K mutation is found only in indica, and indicated a strong association between the RFT1 haplotype and extremely late flowering in a functional Hd1 background. Furthermore, SNPs in the regulatory region of RFT1 and the E105K substitution in 1,397 accessions show strong linkage disequilibrium with a flowering time-associated SNP. Although the defective E105K allele of RFT1 (but not of another florigen gene, Hd3a is found in many cultivars, relative rate tests revealed no evidence for differential rate of evolution of these genes. The ratios of nonsynonymous to synonymous substitutions suggest that the E105K mutation resulting in the defect in RFT1 occurred relatively recently. These findings indicate that natural mutations in RFT1 provide flowering time divergence under long-day conditions.
Rafael Hansen Madail
Full Text Available This study examines the relationship between floral structure and bud quality with the productivity and fruit shape of Gala, Fuji and Daiane apple cultivars under the mild winter conditions in Southern Brazil. Six different types of floral structures were characterized in field growing plants, according to their nature and bud size: spurs, short and long twigs with weak and vigorous buds. Variables related to the phenology and the productivity for these different structures were evaluated. Gala and Fuji cvs. showed earlier phenological development in the twigs, and cv. Daiane in the spurs. For the three cvs. the highest percentage of buds in each phenological phase was observed in the long twigs. The long twigs also showed the highest sprout and fruit set index, floral number per cluster, and leaf area in the three cvs., while the bud abortion was higher in the spurs than in the twigs. No difference was observed among the structures in cvs. Gala and Fuji regarding to the fruit shape. In the cv. Daiane, however, a tendency to higher length diameter ratio of the fruits produced by the long twigs was observed.
Desenvolvimento de gemas florais, florada, fotossíntese e produtividade de cafeeiros em condições de sombreamento Floral buds development, flowering, photosynthesis and yield of coffee plants under shading conditions
Full Text Available O objetivo deste trabalho foi avaliar a influência do sombreamento, durante o período de desenvolvimento floral, sobre as gemas florais, florada, fotossíntese e produtividade de cafeeiros. Cafeeiros adultos IAPAR 59 cultivados em Londrina, PR, foram sombreados em diferentes épocas, com malhas de sombrite com 50% de porosidade, e comparados com cafeeiros cultivados a pleno sol. As coberturas foram colocadas sobre as plantas em intervalos mensais, de abril a agosto, e retiradas no início de outubro. A densidade e o período de sombreamento não tiveram influência sobre a quantidade de nós, em cada estádio de desenvolvimento da gema floral, época e intensidade da florada, fotossíntese e produtividade dos cafeeiros, o que indica que a interceptação de até 50% da radiação, incidente no período de abril a agosto, época de desenvolvimento floral, não afeta o potencial produtivo desta cultura.The objective of this paper was to evaluate the influence of shading, during the period of floral development, on floral bud, flowering, photosynthesis and grain yield of coffee plants. Adult plants IAPAR 59, grown in Londrina, Paraná State, Brazil, were shaded in different periods, with shading screens with 50% porosity, and compared to open-grown plants. The shading screens were placed in monthly intervals, from April to August, and were all removed in the beginning of October. Shading density and period did not influence the amount of nodes in each event of development on floral bud, period and intensity of flowering, photosynthesis and grain yield of the coffee plants, which indicates that the interception of until 50% incident radiation, during the period of floral development, does not affect the yield potential of this crop.
Flowering involves a transition process from vegetative growth to reproductive development, in which a series of routine changes take place in the shoot apical meristems from metabolic pathway to external phenotype. Expression of the genes related to flowering is the foundation for achieving the transition. Environmental factors (such as vernalization and photoperiod) and the growth status of cell itself induce the expression of the specific genes. A lot of achievements have been made recently in gene control for the determination of flowering time. The article reviews some new advances of such researches related to our work and the interesting field.
Kumar, J; van Rheenen, H A
A major gene for the number of days from sowing to appearance of the first flower (time of flowering) was identified in a cross between an extrashort duration chickpea (Cicer arietinum L.) variety, ICCV 2, and a medium duration variety, JG 62. The F2 population was advanced through the single-seed-descent method to develop random recombinant inbred lines (RILs). Time of flowering was recorded for the parents and 66 F(6) RILs from this cross that were grown in a Vertisol field in the post-rainy season of 1996-1997. Similarly the parents, F(1) and F(10) RILs were evaluated in 1997-1998. The F(1) flowered along with JG 62. The time of flowering for the two sets of RILs showed bimodal distributions with nearly equal peaks. One peak corresponded with ICCV 2 and the other with JG 62. This suggests that a single gene controls the difference for the time of flowering between ICCV 2 and JG 62 and the allele carried by the latter parent is dominant. To our knowledge no gene has been identified for the time of flowering in chickpea. Therefore the allele carried by JG 62 is designated as Efl-1 and that by ICCV 2 as efl-1. The proposed genotype for ICCV 2 is efl-1 efl-1 and for JG 62 is Efl-1 Efl-1. The genotype efl-1 efl-1 reduces the time of flowering at ICRISAT by nearly 3 weeks. The significance of this gene for breeding for early maturity and genome mapping has been discussed.
Wolabu, Tezera W; Tadege, Million
Sorghum is a short day plant with strong photoperiod response and its cultivation for grain in temperate regions necessitated the development of photoperiod insensitive mutants that can flower rapidly in the long days of summer. Wild type genotypes grow vegetatively in summer accumulating significant biomass before floral transition ensues during the shorter days of fall. Thus, photoperiod insensitive mutants are grown for grain production while photoperiod sensitive wild type genotypes are grown for forage and biomass feedstock production in the United States. However, the molecular mechanism of photoperiod response and floral transition is poorly understood in sorghum. We have previously reported 3 FLOWERING LOCUS T homologues (SbFT1, SbFT8 and SbFT10) that serve as the ultimate mediators of photoperiod response and floral transition, but more work remains to be done to clearly define the molecular function of the upstream regulatory factors. One of the major QTL that accounts for 85% of the flowering time variation, which was reported to be encoding the PRR37 protein is now debated to be encoding the SbFT12 protein, raising further questions as to how SbFT12 may regulate sorghum florigens. Further molecular analyses will uncover the true nature of the day length sensors in sorghum and the mechanisms of their interactions with florigens to modulate photoperiod dependent vegetative growth and floral transition.
Su, Lei; Shan, Jun-Xiang; Gao, Ji-Ping; Lin, Hong-Xuan
In flowering plants, photoperiodic flowering is controlled by a complicated network. Light is one of the most important environmental stimuli that control the timing of the transition from vegetative growth to reproductive development. Several photoreceptors, including PHYA, PHYB, CRY2, and FKF1 in Arabidopsis and their homologs (OsPHYA, OsPHYB, OsPHYC, and OsCRY2) in rice, have been identified to be related to flowering. Our previous study suggests that OsHAL3, a flavin mononucleotide-binding protein, may function as a blue-light sensor. Here, we report the identification of OsHAL3 as a positive regulator of flowering in rice. OsHAL3 overexpression lines exhibited an early flowering phenotype, whereas downregulation of OsHAL3 expression by RNA interference delayed flowering under an inductive photoperiod (short-day conditions). The change in flowering time was not accompanied by altered Hd1 expression but rather by reduced accumulation of Hd3a and MADS14 transcripts. OsHAL3 and Hd1 colocalized in the nucleus and physically interacted in vivo under the dark, whereas their interaction was inhibited by white or blue light. Moreover, OsHAL3 directly bound to the promoter of Hd3a, especially before dawn. We conclude that OsHAL3, a novel light-responsive protein, plays an essential role in photoperiodic control of flowering time in rice, which is probably mediated by forming a complex with Hd1. Our findings open up new perspectives on the photoperiodic flowering pathway.
Yun Zhou; Xiao-Dong Sun; Min Ni
Flowering symbolizes the transition of a plant from vegetative phase to reproductive phase and is controlled by fairly complex and highly coordinated regulatory pathways. Over the last decade, genetic studies in Arabidopsis have aided the discovery of many signaling components involved in these pathways. In this review, we discuss how the timing of flowering is regulated by photoperiod and the involvement of light perception and the circadian clock in this process. The specific regulatory mechanisms on CONSTANS expression and CONSTANS stability by the circadian clock and photoreceptors are described in detail. In addition, the roles of CONSTANS, FLOWERING LOCUS T, and several other light signaling and circadiandependent components in photoperiodic flowering are also highlighted.
Wagner, Maggie R; Lundberg, Derek S; Coleman-Derr, Devin; Tringe, Susannah G; Dangl, Jeffery L; Mitchell-Olds, Thomas
Plant phenology is known to depend on many different environmental variables, but soil microbial communities have rarely been acknowledged as possible drivers of flowering time. Here, we tested separately the effects of four naturally occurring soil microbiomes and their constituent soil chemistries on flowering phenology and reproductive fitness of Boechera stricta, a wild relative of Arabidopsis. Flowering time was sensitive to both microbes and the abiotic properties of different soils; varying soil microbiota also altered patterns of selection on flowering time. Thus, soil microbes potentially contribute to phenotypic plasticity of flowering time and to differential selection observed between habitats. We also describe a method to dissect the microbiome into single axes of variation that can help identify candidate organisms whose abundance in soil correlates with flowering time. This approach is broadly applicable to search for microbial community members that alter biological characteristics of interest.
Grob, Valentin; Moline, Philip; Pfeifer, Evelin; Novelo, Alejandro R; Rutishauser, Rolf
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.
Corrinne E. Grover
Full Text Available Flowering time control is critically important to all sexually reproducing angiosperms in both natural ecological and agronomic settings. Accordingly, there is much interest in defining the genes involved in the complex flowering-time network and how these respond to natural and artificial selection, the latter often entailing transitions in day-length responses. Here we describe a candidate gene analysis in the cotton genus , which uses homologs from the well-described flowering network to bioinformatically and phylogenetically identify orthologs in the published genome sequence from Ulbr., one of the two model diploid progenitors of the commercially important allopolyploid cottons, L. and L. Presence and patterns of expression were evaluated from 13 aboveground tissues related to flowering for each of the candidate genes using allopolyploid as a model. Furthermore, we use a comparative context to determine copy number variability of each key gene family across 10 published angiosperm genomes. Data suggest a pattern of repeated loss of duplicates following ancient whole-genome doubling events in diverse lineages. The data presented here provide a foundation for understanding both the parallel evolution of day-length neutrality in domesticated cottons and the flowering-time network, in general, in this important crop plant.
Boachon, Benoît; Junker, Robert R; Miesch, Laurence; Bassard, Jean-Etienne; Höfer, René; Caillieaudeaux, Robin; Seidel, Dana E; Lesot, Agnès; Heinrich, Clément; Ginglinger, Jean-François; Allouche, Lionel; Vincent, Bruno; Wahyuni, Dinar S C; Paetz, Christian; Beran, Franziska; Miesch, Michel; Schneider, Bernd; Leiss, Kirsten; Werck-Reichhart, Danièle
The acyclic monoterpene alcohol linalool is one of the most frequently encountered volatile compounds in floral scents. Various linalool oxides are usually emitted along with linalool, some of which are cyclic, such as the furanoid lilac compounds. Recent work has revealed the coexistence of two flower-expressed linalool synthases that produce the (S)- or (R)-linalool enantiomers and the involvement of two P450 enzymes in the linalool oxidation in the flowers of Arabidopsis thaliana. Partially redundant enzymes may also contribute to floral linalool metabolism. Here, we provide evidence that CYP76C1 is a multifunctional enzyme that catalyzes a cascade of oxidation reactions and is the major linalool metabolizing oxygenase in Arabidopsis flowers. Based on the activity of the recombinant enzyme and mutant analyses, we demonstrate its prominent role in the formation of most of the linalool oxides identified in vivo, both as volatiles and soluble conjugated compounds, including 8-hydroxy, 8-oxo, and 8-COOH-linalool, as well as lilac aldehydes and alcohols. Analysis of insect behavior on CYP76C1 mutants and in response to linalool and its oxygenated derivatives demonstrates that CYP76C1-dependent modulation of linalool emission and production of linalool oxides contribute to reduced floral attraction and favor protection against visitors and pests. © 2015 American Society of Plant Biologists. All rights reserved.
Weigel, Detlef; Alvarez, John; Smyth, David R.; Yanofsky, Martin F.; Meyerowitz, Elliot M.
The first step in flower development is the generation of a floral meristem by the inflorescence meristem. We have analyzed how this process is affected by mutant alleles of the Arabidopsis gene LEAFY. We show that LEAFY interacts with another floral control gene, APETALA1, to promote the transition from inflorescence to floral meristem. We have cloned the LEAFY gene, and, consistent with the mutant phenotype, we find that LEAFY RNA is expressed strongly in young flower primordia. LEAFY expre...
Elzinga, J.A.; Atlan, A.; Biere, A.; Gigord, L.; Weis, A.E.; Bernasconi, G.
The role of biotic interactions in shaping plant flowering phenology has long been controversial; plastic responses to the abiotic environment, limited precision of biological clocks and inconsistency of selection pressures have generally been emphasized to explain phenological variation. However, p
The transition to reproductive development is a crucial step of a plant’s life cycle, and the timing of this transition is an important factor in crop yields. Here, we report new insights into the genetic control of natural variation in flowering time in Brachypodium distachyon, a non-domesticated c...
LI Guisheng; MENG Zheng; KONG Hongzhi; CHEN Zhiduan; LU Anming
The paper introduces the classical ABC model of floral development and thereafter ABCD, ABCDE and quartet models, and presents achievements in the studies on floral evolution such as the improved understanding on the relationship of reproductive organs between gnetophytes and angiosperms, new results in perianth evolution and identified homology of floral organs between dicots and monocots. The evo-devo studies on plant taxa at different evolutionary levels are useful to better understanding the homology of floral organs, and to clarifying the mysteries of the origin and subsequent diversification of flowers.
Spigler, Rachel B
Plasticity of floral traits in response to pollination can enable plants to maximize opportunities for pollen import and export under poor pollination conditions, while minimizing costs under favourable ones. Both floral longevity and display are key traits influencing pollination. While pollination-induced flower wilting is widely documented, we lack an understanding of the multifactorial complexity of this response, including the influence of other pollination components, costs of extended longevity and subsequent impacts on floral display. Plasticity of floral longevity was experimentally evaluated in Sabatia angularis in response to multiple pollination factors: pollen addition, removal, and source (self, single-donor outcross, multiple-donor outcross) and timing of pollination. Effects of pollen quantity were further evaluated by exploiting variation in autonomous self-pollen deposition. Delayed pollination costs were tested comparing seed set from early versus late pollinations. Finally, I compared floral display metrics (peak floral display, time to peak flower, flowering duration, mean flowering rate) between experimentally pollinated and control plants. Floral longevity was highly plastic in response to pollen addition and its timing, and the response was dose-dependent but insensitive to pollen source. Pollen removal tended to extend floral longevity, but only insofar as it precluded pollination-induced wilting via autonomous self-pollination. Under delayed pollination, the wilting response was faster and no cost was detected. Pollination further led to reduced peak floral displays and condensed flowering periods. Floral longevity and display plasticity could optimize fitness in S. angularis, a species prone to pollen limitation and high inbreeding depression. Under pollinator scarcity, extended floral longevities offer greater opportunities for pollen receipt and export at no cost to seed set, reproductive assurance via autonomous self-pollination and
Léia fortes Salles
Full Text Available OBJETIVO: Investigar os efeitos dos florais Impatiens, Cherry Plum, White Chestnut e Beech em pessoas ansiosas. MÉTODOS: Estudo de natureza quantitativa, ensaio clínico randomizado, duplo cego. Os dados foram coletados entre maio e agosto de 2010 com 34 trabalhadores do Centro de Aperfeiçoamento em Ciências da Saúde da Fundação Zerbini. A ansiedade foi avaliada por meio do Inventário de Diagnóstico da Ansiedade Traço - Estado em dois momentos diferentes, no início e final da intervenção. RESULTADOS: Como resultado observou-se que o grupo que fez uso das essências florais teve uma diminuição maior e estatisticamente significativa no nível de ansiedade em comparação ao grupo placebo. CONCLUSÃO: Concluiu-se que as essências florais tiveram efeito positivo na diminuição da ansiedade.OBJETIVO: Investigar los efectos de los florales Impatiens, Cherry Plum, White Chestnut y Beech en personas ansiosas. MÉTODOS: Estudio de naturaleza cuantitativa, ensayo clínico randomizado, doble ciego. Los datos fueron recolectados entre mayo y agosto del 2010 con 34 trabajadores del Centro de Perfeccionamiento en Ciencias de la Salud de la Fundación Zerbini. La ansiedad fue evaluada por medio del Inventario de Diagnóstico de la Ansiedad Traço - Estado en dos momentos diferentes, al inicio y final de la intervención. RESULTADOS: Como resultado se observó que el grupo que hizo uso de las esencias florales tuvo una disminución mayor y estadísticamente significativa en el nivel de ansiedad en comparación al grupo placebo. CONCLUSIÓN: Se concluyó que las esencias florales tuvieron efecto positivo en la disminución de la ansiedad.OBJECTIVE: To investigate the effects of the flower essences impatiens, cherry plum, white chestnut and beech in anxious people. METHODS: A quantitative, randomized, double blinded study. Data were collected between May and August, 2010, with 34 employees of the Center for Improvement of Health Sciences of the
Wessinger, Carolyn A; Hileman, Lena C; Rausher, Mark D
Distinct floral pollination syndromes have emerged multiple times during the diversification of flowering plants. For example, in western North America, a hummingbird pollination syndrome has evolved more than 100 times, generally from within insect-pollinated lineages. The hummingbird syndrome is characterized by a suite of floral traits that attracts and facilitates pollen movement by hummingbirds, while at the same time discourages bee visitation. These floral traits generally include large nectar volume, red flower colour, elongated and narrow corolla tubes and reproductive organs that are exerted from the corolla. A handful of studies have examined the genetic architecture of hummingbird pollination syndrome evolution. These studies find that mutations of relatively large effect often explain increased nectar volume and transition to red flower colour. In addition, they suggest that adaptive suites of floral traits may often exhibit a high degree of genetic linkage, which could facilitate their fixation during pollination syndrome evolution. Here, we explore these emerging generalities by investigating the genetic basis of floral pollination syndrome divergence between two related Penstemon species with different pollination syndromes--bee-pollinated P. neomexicanus and closely related hummingbird-pollinated P. barbatus. In an F2 mapping population derived from a cross between these two species, we characterized the effect size of genetic loci underlying floral trait divergence associated with the transition to bird pollination, as well as correlation structure of floral trait variation. We find the effect sizes of quantitative trait loci for adaptive floral traits are in line with patterns observed in previous studies, and find strong evidence that suites of floral traits are genetically linked. This linkage may be due to genetic proximity or pleiotropic effects of single causative loci. Interestingly, our data suggest that the evolution of floral traits
Dally, Nadine; Xiao, Ke; Holtgräwe, Daniela; Jung, Christian
Sugar beet (Beta vulgaris) is a biennial root crop that grows vegetatively in the first year and starts shoot elongation (bolting) and flowering after exposure to cold temperatures over winter. Early bolting before winter is controlled by the dominant allele of the B locus. Recently, the BOLTING TIME CONTROL 1 (BTC1) gene has been cloned from this locus. BTC1 promotes early bolting through repression of the downstream bolting repressor B. vulgaris FLOWERING LOCUS T1 (BvFT1) and activation of the downstream floral activator BvFT2. We have identified a new bolting locus B2 acting epistatically to B. B2 houses a transcription factor which is diurnally regulated and acts like BTC1 upstream of BvFT1 and BvFT2. It was termed BvBBX19 according to its closest homolog from Arabidopsis thaliana. The encoded protein has two conserved domains with homology to zinc finger B-boxes. Ethyl methanesulfonate-induced mutations within the second B-box caused up-regulation of BvFT1 and complete down-regulation of BvFT2. In Arabidopsis, the expression of FT is promoted by the B-box containing protein CONSTANS (CO). We performed a phylogenetic analysis with B-box genes from beet and A. thaliana but only BvCOL1 clustered with CO. However, BvCOL1 had been excluded as a CO ortholog by previous studies. Therefore, a new model for flowering induction in beet is proposed in which BTC1 and BvBBX19 complement each other and thus acquire a CO function to regulate their downstream targets BvFT1 and BvFT2. PMID:24965366
de Viana, M L; Ortega Baes, P; Saravia, M; Badano, E I; Schlumpberger, B
Many columnar cacti are bat pollinated. It has been suggested that this kind of pollination would be more important in tropical than in temperate regions where flowers are open only one night. Thrichocereus pasacana produces big and resistant white flowers. We analyzed flower characteristics, floral cycle, stigmatic receptivity, nectar production, pollen presence and floral visitors in a T. pasacana population at National Park Los Cardones (Salta, Argentina) in November 1997. Flower features were constant between individuals of the population. Flowers start opening at evening and anthesis time is from 18 to 40 hs. The estigma was receptive throughout the floral cycle. Anther dehiscence occurs with flower opening. Nectar production was highest between 18 to 24 hs. Although T. pasacana are open during the night, floral visitors are diurnal. The most frequent was Xylocopa sp. In the study area, nectarivorous bats were not detected. The morphological features of T. pasacana flowers were similar but bigger compared to other columnar cacti. Anthesis time was also longer while nectar production was lower. T. pasacana pollination at National Park Los Cardones is done by bees.
Efeito do Paclobutrazol no controle da diferenciação floral natural do abacaxizeiro cv. Smooth Cayenne Effect of Paclobutrazol in the control of the natural flowering difference of 'Smooth Cayenne' pineapple plant
Andréa Maria Antunes
Full Text Available O abacaxizeiro é uma planta de grande importância econômica, porém seu florescimento natural causa sérios problemas, tornando seu manejo difícil devido à desuniformidade de frutos e colheitas, elevando o custo de produção. O objetivo deste trabalho foi manipular o florescimento do abacaxizeiro, contribuindo para uma produção uniforme colocada no mercado, nos meses de menor oferta. Utilizou-se o Paclobutrazol (PBZ nas concentrações de 100; 150 e 200 mg L-1, em 2; 3 ou 4 aplicações via foliar, em plantas de abacaxi cv. Smooth Cayenne, no município de Presidente Alves-SP. O delineamento empregado foi em blocos ao acaso, com 10 tratamentos e três repetições, com 40 plantas por parcela experimental. No período de 100 a 150 dias após a primeira aplicação dos tratamentos, efetuaram-se as contagens de inflorescências presentes no centro da roseta foliar das plantas. Todos os tratamentos com Paclobutrazol inibiram a diferenciação floral natural do abacaxizeiro, recomendando-se a concentração de 150 mg L-1 em duas aplicações, com início em abril, a intervalo de 15 dias.The pineapple plant is a plant of great economical importance, however, its natural flowering causes serious problems, turning it difficult to manage it due to the fruit and harvest irregularity, elevating the production's cost. The objective of this work was to manipulate the pineapple flowering contributing indeed for a more uniform production on the market, during the months of lower offer. The Paclobutrazol was used in pineapple plants cv. Smooth Cayenne at concentrations of 100; 150 and 200 mg L-1 and applied in 2, 3 or 4 times, in Presidente Alves-SP. The experimental design was randomized blocks with 10 treatments and three replications, each experimental portion of 40 plants. In the period of 100 to 150 days after the first application of the treatments, the number of inflorescences present in the center of the plants were counted each week. All of the
Mullet, John E.; Rooney, William L.
Methods and composition for the production of sorghum hybrids with selected and different flowering times are provided. In accordance with the invention, a substantially continual and high-yield harvest of sorghum is provided. Improved methods of seed production are also provided.
Mullet, John E.; Rooney, William L.
Methods and composition for the production of sorghum hybrids with selected and different flowering times are provided. In accordance with the invention, a substantially continual and high-yield harvest of sorghum is provided. Improved methods of seed production are also provided.
Zhong-Lai LUO; Shi CHEN; Dian-Xiang ZHANG
Animal-pollinated plant species modulate the presentation of pollinator rewards to maximize reproductive success.In plants providing pollen as the only reward for pollinators,it is usually difficult to unravel the dual roles of reward presentation and the realization of male and female functions (pollen removal and deposition).Exploiting the two types of anther in the androecia of Melastoma malabathricum L.,we examined whether the removal of pollen for reward is regulated primarily to favor male function or female function.Pollen removal by carpenter bees from the feeding and pollination anthers,as well as pollen deposition on the stigmas,were quantified during anthesis of M.malabathricum.There was no significant difference in pollen removal rates from the feeding and pollination anthers of M.malabathricum between the onset of anthesis and flower wilting.The stigmatic pollen loads exceeded the ovule number after three sonication bouts,and female function was satisfied earlier than male function.The results support the hypothesis that the presentation of pollination reward in this species is regulated primarily to favor the expression of male function,rather than female function,in agreement with the pollen-donation hypothesis.A cooperative relationship between the feeding and pollination anthers was demonstrated in heterantherous flowers,which optimizes the balance in investments between pollinator rewards and "functional pollen" for gene transfer.
Kusters, E.; Della Pina, S.; Castel, R.; Souer, E.; Koes, R.
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
Kusters, E.; Della Pina, S.; Castel, R.; Souer, E.; Koes, R.
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 ch
Hammad, I.; Van Tienderen, P.H.
Genetic variation in flowering time was studied in four natural populations of Arabidopsis thaliana, using greenhouse experiments. Two populations from ruderal sites flowered early, two others from river dykes late. However, the late flowering plants flowered almost as early as the others after cold
Levin, J Z; Meyerowitz, E M
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.
pistil. In the other severe pruning dates, the floral differentiation was reduced, decreasing the flower-buds quantity. In the control peach trees, without severe pruning, the floral organogenesis normally occurred from January to March. The floral induction began, probably, in early summer (December and persisted until fall (April.
Van Tienderen, P.H.; Hammad, I.; Zwaal, F.C.
Variation in flowering time of Arabidopsis thaliana was studied in an experiment with mutant lines. The pleiotropic effects of flowering time genes on morphology and reproductive yield were assessed under three levels of nutrient supply. At all nutrient levels flowering time and number of rosette le
Jung, Won Yong; Park, Hyun Ji; Lee, Areum; Lee, Sang Sook; Kim, Youn-Sung; Cho, Hye Sun
Late bolting after cold exposure is an economically important characteristic of radish (Raphanus sativus L.), an important Brassicaceae root vegetable crop. However, little information is available regarding the genes and pathways that govern flowering time in this species. We performed high-throughput RNA sequencing analysis to elucidate the molecular mechanisms that determine the differences in flowering times between two radish lines, NH-JS1 (late bolting) and NH-JS2 (early bolting). In total, 71,188 unigenes were identified by reference-guided assembly, of which 309, 788, and 980 genes were differentially expressed between the two inbred lines after 0, 15, and 35 days of vernalization, respectively. Among these genes, 218 homologs of Arabidopsis flowering-time (Ft) genes were identified in the radish, and 49 of these genes were differentially expressed between the two radish lines in the presence or absence of vernalization treatment. Most of the Ft genes up-regulated in NH-JS1 vs. NH-JS2 were repressors of flowering, such as RsFLC, consistent with the late-bolting phenotype of NH-JS1. Although, the functions of genes down-regulated in NH-JS1 were less consistent with late-bolting characteristics than the up-regulated Ft genes, several Ft enhancer genes, including RsSOC1, a key floral integrator, showed an appropriate expression to the late-bolting phenotype. In addition, the patterns of gene expression related to the vernalization pathway closely corresponded with the different bolting times of the two inbred lines. These results suggest that the vernalization pathway is conserved between radish and Arabidopsis. PMID:28018383
Hye Sun Cho
Full Text Available Late bolting after cold exposure is an economically important characteristic of radish (Raphanus sativus L., an important Brassicaceae root vegetable crop. However, little information is available regarding the genes and pathways that govern flowering time in this species. We performed high-throughput RNA sequencing analysis to elucidate the molecular mechanisms that determine the differences in flowering times between two radish lines, NH-JS1 (late bolting and NH-JS2 (early bolting. In total, 71,188 unigenes were identified by reference-guided assembly, of which 309, 788, and 980 genes were differentially expressed between the two inbred lines after 0, 15, and 35 days of vernalization, respectively. Among these genes, 218 homologs of Arabidopsis flowering-time (Ft genes were identified in the radish, and 49 of these genes were differentially expressed between the two radish lines in the presence or absence of vernalization treatment. Most of the Ft genes up-regulated in NH-JS1 vs NH-JS2 were repressors of flowering, such as RsFLC, consistent with the late-bolting phenotype of NH-JS1. Although the functions of genes down-regulated in NH-JS1 were less consistent with late-bolting characteristics than the up-regulated Ft genes, several Ft enhancer genes, including RsSOC1, a key floral integrator, showed an appropriate expression to the late-bolting phenotype. In addition, the patterns of gene expression related to the vernalization pathway closely corresponded with the different bolting times of the two inbred lines. These results suggest that the vernalization pathway is conserved between radish and Arabidopsis.
Thiboutot, D M; Hamory, B H; Marks, J G
Concern about the increasing incidence of hand dermatitis in floral shop workers in the United States and its possible association to the plant Alstroemeria, a flower that has become popular since its introduction in 1981, prompted investigation of the prevalence and cause of hand dermatitis in a sample of floral workers. Fifty-seven floral workers were surveyed, and 15 (26%) reported hand dermatitis within the previous 12 months. Sixteen floral workers (eight with dermatitis) volunteered to be patch tested to the North American Contact Dermatitis Group Standard and Perfume Trays, a series of eight pesticides and 20 plant allergens. Of four of seven floral designers and arrangers who reported hand dermatitis, three reacted positively to patch tests to tuliposide A, the allergen in Alstroemeria. Patch test readings for all other plant extracts were negative. A positive reading for a test to one pesticide, difolatan (Captafol), was noted, the relevance of which is unknown.
Liew, Lim Chee; Singh, Mohan B; Bhalla, Prem L
Legumes, with their unique ability to fix atmospheric nitrogen, play a vital role in ensuring future food security and mitigating the effects of climate change because they use less fossil energy and produce less greenhouse gases compared with N-fertilized systems. Grain legumes are second only to cereal crops as a source of human and animal food, and they contribute approximately one third of the protein consumed by the human population. The productivity of seed crops, such as grain legumes, is dependent on flowering. Despite the genetic variation and importance of flowering in legume production, studies of the molecular pathways that control flowering in legumes are limited. Recent advances in genomics have revealed that legume flowering pathways are divergent from those of such model species as Arabidopsis thaliana. Here, we discuss the current understanding of flowering time regulation in legumes and highlight the unique and conserved features of floral evocation in legumes.
Lim Chee Liew; Mohan B.Singh; Prem L.Bhalla
Legumes, with their unique ability to fix atmo-spheric nitrogen, play a vital role in ensuring future food security and mitigating the effects of climate change because they use less fossil energy and produce less greenhouse gases compared with N-fertilized systems. Grain legumes are second only to cereal crops as a source of human and animal food, and they contribute approximately one third of the protein consumed by the human population. The productivity of seed crops, such as grain legumes, is dependent on flowering. Despite the genetic variation and importance of flowering in legume production, studies of the molecular pathways that control flowering in legumes are limited. Recent advances in genomics have revealed that legume flowering pathways are divergent from those of such model species as Arabidopsis thaliana. Here, we discuss the current understanding of flowering time regulation in legumes and highlight the unique and conserved features of floral evocation in legumes.
Acosta M., Emma M.; Salud Pública. Facultad de Farmacia y Bioquímica de la Universidad Nacional Mayor de San Marcos, Lima, Perú.; Villarán, Jhon Eddowes; Facultad de Psicología. Universidad Garcilaso de la Vega.
The work is a style of research: "Research in Action," which is the small-scale intervention in the functioning of the real world and a clase examination of the effects of such intervention, the ultimate goal being to improve practice. How to improve the practice af floral therapy in our country? Have the input for the preparation of flower remedies and therefore at this stage I had to get 21 flower essences Peruvian natural resources, in order to access and availability of floral therapy. Wh...
Segarra, Silvia; Mir, Ricardo; Martínez, Cristina; León, José
Salicylic acid (SA) has been characterized as an activator of pathogen-triggered resistance of plants. SA also regulates developmental processes such as thermogenesis in floral organs and stress-induced flowering. To deepen our knowledge of the mechanism underlying SA regulation of flowering time in Arabidopsis, we compared the transcriptomes of SA-deficient late flowering genotypes with wild-type plants. Down- or up-regulated genes in SA-deficient plants were screened for responsiveness to ultraviolet (UV)-C light, which accelerates flowering in Arabidopsis. Among them, only Pathogen and Circadian Controlled 1 (PCC1) was up-regulated by UV-C light through a SA-dependent process. Moreover, UV-C light-activated expression of PCC1 was also dependent on the flowering activator CONSTANS (CO). PCC1 gene has a circadian-regulated developmental pattern of expression with low transcript levels after germination that increased abruptly by day 10. RNAi plants with very low expression of PCC1 gene were late flowering, defective in UV-C light acceleration of flowering and contained FLOWERING LOCUS T (FT) transcript levels below 5% of that detected in wild-type plants. Although PCC1 seems to function between CO and FT in the photoperiod-dependent flowering pathway, transgenic plants overexpressing a Glucocorticoid Receptor (GR)-fused version of CO strongly activated FT but not PCC1 after dexamethasone treatment.
Yasui, Yukiko; Kohchi, Takayuki
Floral transition is regulated by environmental and endogenous signals. Previously, we identified VASCULAR PLANT ONE-ZINC FINGER1 (VOZ1) and VOZ2 as phytochrome B-interacting factors. VOZ1 and VOZ2 redundantly promote flowering and have pivotal roles in the downregulation of FLOWERING LOCUS C (FLC), a central repressor of flowering in Arabidopsis. Here, we showed that the late-flowering phenotypes of the voz1 voz2 mutant were suppressed by vernalization in the Columbia and FRIGIDA (FRI)-containing accessions, which indicates that the late-flowering phenotype of voz1 voz2 mutants was caused by upregulation of FLC. We also showed that the other FLC clade members, MADS AFFECTING FLOWERING (MAF) genes, were also a downstream target of VOZ1 and VOZ2 as their expression levels were also increased in the voz1 voz2 mutant. Our results suggest that the FLC clade genes integrate signals from VOZ1/VOZ2 and vernalization to regulate flowering.
Roberts, Wade R; Roalson, Eric H
Flowers have an amazingly diverse display of colors and shapes, and these characteristics often vary significantly among closely related species. The evolution of diverse floral form can be thought of as an adaptive response to pollination and reproduction, but it can also be seen through the lens of morphological and developmental constraints. To explore these interactions, we use RNA-seq across species and development to investigate gene expression and sequence evolution as they relate to the evolution of the diverse flowers in a group of Neotropical plants native to Mexico-magic flowers (Achimenes, Gesneriaceae). The assembled transcriptomes contain between 29,000 and 42,000 genes expressed during development. We combine sequence orthology and coexpression clustering with analyses of protein evolution to identify candidate genes for roles in floral form evolution. Over 25% of transcripts captured were distinctive to Achimenes and overrepresented by genes involved in transcription factor activity. Using a model-based clustering approach we find dynamic, temporal patterns of gene expression among species. Selection tests provide evidence of positive selection in several genes with roles in pigment production, flowering time, and morphology. Combining these approaches to explore genes related to flower color and flower shape, we find distinct patterns that correspond to transitions of floral form among Achimenes species. The floral transcriptomes developed from four species of Achimenes provide insight into the mechanisms involved in the evolution of diverse floral form among closely related species with different pollinators. We identified several candidate genes that will serve as an important and useful resource for future research. High conservation of sequence structure, patterns of gene coexpression, and detection of positive selection acting on few genes suggests that large phenotypic differences in floral form may be caused by genetic differences in a small
Full Text Available Abstract Background We are studying the regulation of flowering in perennial plants by using diploid wild strawberry (Fragaria vesca L. as a model. Wild strawberry is a facultative short-day plant with an obligatory short-day requirement at temperatures above 15°C. At lower temperatures, however, flowering induction occurs irrespective of photoperiod. In addition to short-day genotypes, everbearing forms of wild strawberry are known. In 'Baron Solemacher' recessive alleles of an unknown repressor, SEASONAL FLOWERING LOCUS (SFL, are responsible for continuous flowering habit. Although flower induction has a central effect on the cropping potential, the molecular control of flowering in strawberries has not been studied and the genetic flowering pathways are still poorly understood. The comparison of everbearing and short-day genotypes of wild strawberry could facilitate our understanding of fundamental molecular mechanisms regulating perennial growth cycle in plants. Results We have searched homologs for 118 Arabidopsis flowering time genes from Fragaria by EST sequencing and bioinformatics analysis and identified 66 gene homologs that by sequence similarity, putatively correspond to genes of all known genetic flowering pathways. The expression analysis of 25 selected genes representing various flowering pathways did not reveal large differences between the everbearing and the short-day genotypes. However, putative floral identity and floral integrator genes AP1 and LFY were co-regulated during early floral development. AP1 mRNA was specifically accumulating in the shoot apices of the everbearing genotype, indicating its usability as a marker for floral initiation. Moreover, we showed that flowering induction in everbearing 'Baron Solemacher' and 'Hawaii-4' was inhibited by short-day and low temperature, in contrast to short-day genotypes. Conclusion We have shown that many central genetic components of the flowering pathways in Arabidopsis can
XIANG Chao; QU Li-jun; GAO Yong-ming; SHI Ying-yao
Floral transition,which is referred to as a plant's transition from vegetative stage to reproductive stage,is considered to be a critical developmental switch in higher plants,for a timely flowering is a major factor of reproductive success.Endogenous and environmental cues,such as photoperiod,light quality,plant hormones concentrations and temperature,provide information to the plants whether the environment is favorable for flowering.These cues promote,or prevent,flowering through a complex genetic network,mediated by a careful orchestration of temporal and spatial gene expression.One of such cues is photoperiod.Rice (Oryza sativa L.) serves as a powerful model species for the understanding of flowering in higher plants,including flower development and photoperiodic control of flowering.In this review,we overviewed and discussed the flower development and its model.We also overviewed the photoperiodic pathways in rice flowering control,and summarized the pathways at molecular level.
Petanidou, T.; Van Laere, A.; Ellis, W.; Smets, E.
We studied the amino acid (AA) composition of the floral nectars of 73 plant species occurring in a phryganic (East Mediterranean garrigue) community and investigated whether AA and sugar composition is shaped by evolutionary (plant phylogeny), ecological (flowering time as a direct effect of summer
Tal, Lior; Friedlander, Gilgi; Gilboa, Netta Segal; Unger, Tamar; Gilad, Shlomit; Eshed, Yuval
Enlargement and doming of the shoot apical meristem (SAM) is a hallmark of the transition from vegetative growth to flowering. While this change is widespread, its role in the flowering process is unknown. The late termination (ltm) tomato (Solanum lycopersicum) mutant shows severely delayed flowering and precocious doming of the vegetative SAM LTM encodes a kelch domain-containing protein, with no link to known meristem maintenance or flowering time pathways. LTM interacts with the TOPLESS corepressor and with several transcription factors that can provide specificity for its functions. A subgroup of flowering-associated genes is precociously upregulated in vegetative stages of ltm SAMs, among them, the antiflorigen gene SELF PRUNING (SP). A mutation in SP restored the structure of vegetative SAMs in ltm sp double mutants, and late flowering was partially suppressed, suggesting that LTM functions to suppress SP in the vegetative SAM In agreement, SP-overexpressing wild-type plants exhibited precocious doming of vegetative SAMs combined with late flowering, as found in ltm plants. Strong flowering signals can result in termination of the SAM, usually by its differentiation into a flower. We propose that activation of a floral antagonist that promotes SAM growth in concert with floral transition protects it from such terminating effects. © 2017 American Society of Plant Biologists. All rights reserved.
Guilbaud, Camille S E; Dalchau, Neil; Purves, Drew W; Turnbull, Lindsay A
Flowering time in annual plants has large fitness consequences and has been the focus of theoretical and empirical study. Previous theory has concluded that flowering time has evolved over evolutionary time to maximize fitness over a particular season length. We introduce a new model where flowering is cued by a growth-rate rule (peak nitrogen (N)). Flowering is therefore sensitive to physiological parameters and to current environmental conditions, including N availability and the presence of competitors. The model predicts that, when overall conditions are suitable for flowering, plants should never flower after 'peak N', the point during development when the whole-plant N uptake rate reaches its maximum. Our model further predicts correlations between flowering time and vegetative growth rates, and that the response to increased N depends heavily on how this extra N is made available. We compare our predictions to observations in the literature. We suggest that annual plants may have evolved to use growth-rate rules as part of the cue for flowering, allowing them to smoothly and optimally adjust their flowering time to a wide range of local conditions. If so, there are widespread implications for the study of the molecular biology behind flowering pathways.
Hicks, D.M.; Ouvrard, P.; Baldock, K.C.R.; Baude, M.; Goddard, M. A.; Kunin, W.E.; Mitschunas, N.; Memmott, J; Morse, H; Nikolitsi, M; Osgathorpe, L.M.; Potts, S. G.; Robertson, K. M.; Scott, A.V.; Sinclair, F.
Planted meadows are increasingly used to improve the biodiversity and aesthetic amenity value of urban areas. Although many ‘pollinator-friendly’ seed mixes are available, the floral resources these provide to flower-visiting insects, and how these change through time, are largely unknown. Such data are necessary to compare the resources provided by alternative meadow seed mixes to each other and to other flowering habitats. We used quantitative surveys of over 2 million flowers to estimate t...
Mario Augusto Gonçalves Jardim
floral bud phase to senescence stage in male flowers and fruit formation in female flowers. Biochemical tests were carried out to verify odor, pigment, osmophore pigments and stigma receptivity. Floral visitors were observed during the diurnal period and visiting time, flower permanence time and frequency were recorded. Some individuals were collected with entomological net and identified by the Zoology Department of the Emílio Goeldi Paranaense Museum. Anthesis occurred between 06:00 a.m. and 4:00 p.m. in the staminate flowers, and between 8:00 a.m. and 4:00 p.m. for the pistilate flowers. Odor was reported only in the staminate flowers and osmophore pigments in both flowers types. The stigma showed to be receptive between 12:00 and 2:00 p.m. Diptera order insects were the most frequent visitors on the staminate and pistilate flowers. The Copestylum sp. and Erystalys sp. were responsible for pollination.
Wysocki, William P; Ruiz-Sanchez, Eduardo; Yin, Yanbin; Duvall, Melvin R
Next-generation sequencing now allows for total RNA extracts to be sequenced in non-model organisms such as bamboos, an economically and ecologically important group of grasses. Bamboos are divided into three lineages, two of which are woody perennials with bisexual flowers, which undergo gregarious monocarpy. The third lineage, which are herbaceous perennials, possesses unisexual flowers that undergo annual flowering events. Transcriptomes were assembled using both reference-based and de novo methods. These two methods were tested by characterizing transcriptome content using sequence alignment to previously characterized reference proteomes and by identifying Pfam domains. Because of the striking differences in floral morphology and phenology between the herbaceous and woody bamboo lineages, MADS-box genes, transcription factors that control floral development and timing, were characterized and analyzed in this study. Transcripts were identified using phylogenetic methods and categorized as A, B, C, D or E-class genes, which control floral development, or SOC or SVP-like genes, which control the timing of flowering events. Putative nuclear orthologues were also identified in bamboos to use as phylogenetic markers. Instances of gene copies exhibiting topological patterns that correspond to shared phenotypes were observed in several gene families including floral development and timing genes. Alignments and phylogenetic trees were generated for 3,878 genes and for all genes in a concatenated analysis. Both the concatenated analysis and those of 2,412 separate gene trees supported monophyly among the woody bamboos, which is incongruent with previous phylogenetic studies using plastid markers.
Víctor Julio Flórez Roncancio
SD. In this work new indications of the relationship between phytohormones present in the acid fraction and flowering process were explored. In the first assay, leaf extracts of plants under long days (LD (characterized by slower time of floral anthesis, were applied in flower buds of plants under short days (characterized by speeding up floral anthesis. On the whole, eight applications were carried out with different frequencies summarizing a treatment period of 25 days. The results showed that the substances present in the extracts of the acid fraction do not alter the time of floral anthesis in the flower buds of plants kept in SD; likewise, was confirmed a longer time for floral anthesis in plants control under LD. In the second assay, the ELISA quantification allowed to establish higher concentrations of ABA in leaf and flower buds extracts of plants under SD and in flower buds at the beginning of the treatments. These results confirm the relation of ABA with speeding up floral anthesis in Solidago x luteus plants kept in SD conditions.
Yu, Qin; Jia, Dong-Rui; Tian, Bin; Yang, Yong-Ping; Duan, Yuan-Wen
Responses of plant traits to climate changes are complex, which could be mirrored by the investigations of herbarium specimens. By examining specimens of Rosa and Cotoneaster species collected since 1920s in Hengduan Mountains, we analyzed the changes of flowering phenology and flower size in the past century when climate changes were considered to be intensified. We found that flowering phenology of Rosa showed no significant change, but flowering phenology of Cotoneaster was delayed in recent years. Flower size of Rosa species showed a marginally significant decrease over the past century. The results suggested that responses of flowering time to global changes and pollinator mediated selection on floral traits might be more complex than what were expected. Our results indicated that future researches based on investigations of herbarium specimens should be carried out on multiple plant species with different flower structures and life histories to better understand the effects of climate changes on plant traits.
Schiestl, Florian P; Johnson, Steven D
Because most plants rely on animals for pollination, insights from animal sensory ecology and behavior are essential for understanding the evolution of flowers. In this review, we compare and contrast three main types of pollinator responses to floral signals--receiver bias, 'adaptive' innate preferences, and associative learning--and discuss how they can shape selection on floral signals. We show that pollinator-mediated selection on floral signals can be strong and that the molecular bases of floral signal variation are often surprisingly simple. These new empirical and conceptual insights into pollinator-mediated evolution provide a framework for understanding patterns of both convergent (pollination syndromes) and advergent (floral mimicry) floral signal evolution. Copyright © 2013 Elsevier Ltd. All rights reserved.
Maria de Jesus Vitali
Full Text Available A study of the reproductive biology of B. chinensis (L. DC. (Iridaceae was realized comprising floral biology and breeding systems. The floral biology studies included analyses of nectar production, occurence of osmophores, corolla pigments, ultraviolet reflexion and absortion patterns, viability of pollen, pollinators and flower visitors. The breeding systems were studied taking into account the results of manual pollinators tests. B. chinensis is self-compatible bul cross-pollination is more frequent. The effective pollinators are Plebeia droryana (Friese, 1906 (45,7%, Trigona spinipes (Fabricius, 1793 (27,3%, Tetragonisca angustula (Latreille, 1811 (9,3%. Others insects visitors are considered nectar and pollen thieves. The flowering begins generally in January and February. The complete reproductive cicle, as here considered, begining with floral bud production ending with development of mature fruits, lasts January to June. Seed dispersion is ornitocoric.
Full Text Available Esse estudo teve por objetivo caracterizar variações na arquitetura floral da Feijoa sellowiana e determinar sua influência sobre a polinização. Foram avaliados o comprimento do pistilo, a distância entre estigma e estames, o diâmetro de abertura e a distribuição dos estames na flor, com base em 7 flores de 15 acessos do Banco de Germoplasma da espécie. Distinguiram-se 3 classes de distâncias médias entre estigma e estames: 0,2 (C1, 0,7 (C2 e 1,2 cm (C3, e duas classes de distribuição de estames na flor (radial e aleatória. Sorteou-se uma planta por classe de distância entre estigma e estames, a qual teve 50 flores marcadas para cada um dos seguintes tratamentos: T1-polinização aberta; T2-tela contra pássaros e T3-tela contra pássaros e insetos. A frutificação foi de 47% em T1 para C2 e de 22% para C3, diferença que pode ser devida ao genótipo e/ou alternância de produção. No T2, a frutificação foi 31% em C2, 15,4% em C1 e 3% em C3. A superioridade de T1 sobre T2 pode ser devida à polinização por pássaros. Essa superioridade foi mais expressiva em C3 do que em C2, o que sugere que C3 é mais dependente de pássaros. A frutificação em T2 pode ainda evidenciar a polinização por insetos e foi menor para C3, o que pode estar sendo causado pelo maior afastamento do estigma. A frutificação em T3 para C1 (7% e C2 (15% sugere que o vento ou a autopolinização também possam efetuar a polinização.The objective of our research was to evaluate distance between the stigma and the stamens, opening diameter and stamens distribution on the flower. We evaluated these variables on 7 flowers of each one of the 15 plant accessions from the Germplasm Bank. The flowers were classified according to distance between the stigma and the stamens into three classes: 0.2 (C1, 0.7 (C2 and 1,2 (C3 cm, in which 2, 9, and 4 accessions were included, respectively. The radial and random stamens distributions were verified in 6 and 9
Hayes, Felicity; Williamson, Jennifer; Mills, Gina
Mesocosms representing the BAP Priority habitat 'Calcareous Grassland' were exposed to eight ozone profiles for twelve-weeks in two consecutive years. Half of the mesocosms received a reduced watering regime during the exposure periods. Numbers and timing of flowering in the second exposure period were related to ozone concentration and phytotoxic ozone dose (accumulated stomatal flux). For Lotus corniculatus, ozone accelerated the timing of the maximum number of flowers. An increase in mean ozone concentration from 30ppb to 70ppb corresponded with an advance in the timing of maximum flowering by six days. A significant reduction in flower numbers with increasing ozone was found for Campanula rotundifolia and Scabiosa columbaria and the relationship with ozone was stronger for those that were well-watered than for those with reduced watering. These changes in flowering timing and numbers could have large ecological impacts, affecting plant pollination and the food supply of nectar feeding insects.
Chang-Qiu LIU; Shuang-Quan HUANG
Variation in floral allocation within inflorescences has been attributed to resource competition and/or architectural effect.The two hypotheses were extensively studied and both hypotheses were partly supported by previous studies.However,the relative importance of resource competition and architectural effect may vary with stages of floral ontogeny in a species.To detect the effects ofontogenetic stages on floral variation,we manipulated the 6-flowered inflorescences ofAdenophorajasionifolia (Campanulaceae) by early,late,and non-thinning flowers.Our results indicated that pollen and ovule production of the remaining flowers were not significantly different between early and late thinning manipulations,suggesting that floral sex allocation was determined far before flowering,in support of the architectural effect hypothesis.Under hand-pollination treatments,early thinning but not late thinning resulted in a significant increase in seed number and seed set of the remaining flowers.Therefore,the increase in seed production of the remaining flowers related to the floral ontogeny.The resource competition for floral allocation was significant under early thinning rather than late thinning manipulation.Our results suggest that studies on floral variation within inflorescences should take into account the stages of floral ontogeny.
Srivastava, Rishi; Upadhyaya, Hari D.; Kumar, Rajendra; Daware, Anurag; Basu, Udita; Shimray, Philanim W.; Tripathi, Shailesh; Bharadwaj, Chellapilla; Tyagi, Akhilesh K.; Parida, Swarup K.
Identification of functionally relevant potential genomic loci using an economical, simpler and user-friendly genomics-assisted breeding strategy is vital for rapid genetic dissection of complex flowering time quantitative trait in chickpea. A high-throughput multiple QTL-seq strategy was employed in two inter (Cicer arietinum desi accession ICC 4958 × C reticulatum wild accession ICC 17160)- and intra (ICC 4958 × C. arietinum kabuli accession ICC 8261)-specific RIL mapping populations to identify the major QTL genomic regions governing flowering time in chickpea. The whole genome resequencing discovered 1635117 and 592486 SNPs exhibiting differentiation between early- and late-flowering mapping parents and bulks, constituted by pooling the homozygous individuals of extreme flowering time phenotypic trait from each of two aforesaid RIL populations. The multiple QTL-seq analysis using these mined SNPs in two RIL mapping populations narrowed-down two longer (907.1 kb and 1.99 Mb) major flowering time QTL genomic regions into the high-resolution shorter (757.7 kb and 1.39 Mb) QTL intervals on chickpea chromosome 4. This essentially identified regulatory as well as coding (non-synonymous/synonymous) novel SNP allelic variants from two efl1 (early flowering 1) and GI (GIGANTEA) genes regulating flowering time in chickpea. Interestingly, strong natural allelic diversity reduction (88–91%) of two known flowering genes especially mapped at major QTL intervals as compared to that of background genomic regions (where no flowering time QTLs were mapped; 61.8%) in cultivated vis-à-vis wild Cicer gene pools was evident inferring the significant impact of evolutionary bottlenecks on these loci during chickpea domestication. Higher association potential of coding non-synonymous and regulatory SNP alleles mined from efl1 (36–49%) and GI (33–42%) flowering genes for early and late flowering time differentiation among chickpea accessions was evident. The robustness and
Shu, Kai; Chen, Qian; Wu, Yaorong; Liu, Ruijun; Zhang, Huawei; Wang, Shengfu; Tang, Sanyuan; Yang, Wenyu; Xie, Qi
During the life cycle of a plant, one of the major biological processes is the transition from the vegetative to the reproductive stage. In Arabidopsis, flowering time is precisely controlled by extensive environmental and internal cues. Gibberellins (GAs) promote flowering, while abscisic acid (ABA) is considered as a flowering suppressor. However, the detailed mechanism through which ABA inhibits the floral transition is poorly understood. Here, we report that ABSCISIC ACID-INSENSITIVE 4 (ABI4), a key component in the ABA signalling pathway, negatively regulates floral transition by directly promoting FLOWERING LOCUS C (FLC) transcription. The abi4 mutant showed the early flowering phenotype whereas ABI4-overexpressing (OE-ABI4) plants had delayed floral transition. Consistently, quantitative reverse transcription–PCR (qRT–PCR) assay revealed that the FLC transcription level was down-regulated in abi4, but up-regulated in OE-ABI4. The change in FT level was consistent with the pattern of FLC expression. Chromatin immunoprecipitation-qPCR (ChIP-qPCR), electrophoretic mobility shift assay (EMSA), and tobacco transient expression analysis showed that ABI4 promotes FLC expression by directly binding to its promoter. Genetic analysis demonstrated that OE-ABI4::flc-3 could not alter the flc-3 phenotype. OE-FLC::abi4 showed a markedly delayed flowering phenotype, which mimicked OE-FLC::WT, and suggested that ABI4 acts upstream of FLC in the same genetic pathway. Taken together, these findings suggest that ABA inhibits the floral transition by activating FLC transcription through ABI4. PMID:26507894
Dierlei dos Santos
plant per plot. From 02/01/2008 until 04/30/2008, four plants were taken from each growth chamber (CC (temperatures: 16/12°C (day/night; air humidity: 70%; photoperiod: 10 hours; photosynthetic photon flux density: 100µmol m-2 s-1 to 15 days and taken to a greenhouse (CV without environmental control, totaling seven dates of transfer. Exposure of plants to low temperatures, under controlled conditions, does not cause significant changes in the characteristics of chlorophyll a fluorescence, but caused 80% of reduction in gas exchange. This reduction does not hurt the flowering plants. Plants exposed to no-induced conditions only issued vegetative shoots, while those submitted to lower temperatures, the greater was the exposure time, the greater was the number of flowers sent.
Banday, Zeeshan Z; Nandi, Ashis K
The ability to avoid or neutralize pathogens is inherent to all higher organisms including plants. Plants recognize pathogens through receptors, and mount resistance against the intruders, with the help of well-elaborated defense arsenal. In response to some localinfections, plants develop systemic acquired resistance (SAR), which provides heightened resistance during subsequent infections. Infected tissues generate mobile signaling molecules that travel to the systemic tissues, where they epigenetically modify expression o a set of genes to initiate the manifestation of SAR in distant tissues. Immune responses are largely regulated at transcriptional level. Flowering is a developmental transition that occurs as a result of the coordinated action of large numbers of transcription factors that respond to intrinsic signals and environmental conditions. The plant hormone salicylic acid (SA) which is required for SAR activation positively regulates flowering. Certain components of chromatin remodeling complexes that are recruited for suppression of precocious flowering are also involved in suppression of SAR in healthy plants. FLOWERING LOCUS D, a putative histone demethylase positively regulates SAR manifestation and flowering transition in Arabidopsis. Similarly, incorporation of histone variant H2A.Z in nucleosomes mediated by PHOTOPERIOD-INDEPENDENT EARLY FLOWERING 1, an ortholog of yeast chromatin remodeling complex SWR1, concomitantly influences SAR and flowering time. SUMO conjugation and deconjugation mechanisms also similarly affect SAR and flowering in an SA-dependent manner. The evidences suggest a common underlying regulatory mechanism for activation of SAR and flowering in plants.
Full Text Available Plants have developed sophisticated systems to adapt to local conditions during evolution, domestication and natural or artificial selection. The selective pressures of these different growing conditions have caused significant genomic divergence within species. The flowering time trait is the most crucial factor because it helps plants to maintain sustainable development. Controlling flowering at appropriate times can also prevent plants from suffering from adverse growth conditions, such as drought, winter hardness, and disease. Hence, discovering the genome-wide genetic mechanisms that influence flowering time variations and understanding their contributions to adaptation should be a central goal of plant genetics and genomics. A global core collection panel with 448 inbred rapeseed lines was first planted in four independent environments, and their flowering time traits were evaluated. We then performed a genome-wide association mapping of flowering times with a 60 K SNP array for this core collection. With quality control and filtration, 20,342 SNP markers were ultimately used for further analyses. In total, 312 SNPs showed marker-trait associations in all four environments, and they were based on a threshold p value of 4.06x10-4; the 40 QTLs showed significant association with flowering time variations. To explore flowering time QTLs and genes related to growth habits in rapeseed, selection signals related to divergent habits were screened at the genome-wide level and 117 genomic regions were found. Comparing locations of flowering time QTLs and genes with these selection regions revealed that 20 flowering time QTLs and 224 flowering time genes overlapped with 24 and 81 selected regions, respectively. Based on this study, a number of marker-trait associations and candidate genes for flowering time variations in rapeseed were revealed. Moreover, we also showed that both flowering time QTLs and genes play important roles in rapeseed growth
Song, Young Hun; Ito, Shogo; Imaizumi, Takato
Plants monitor changes in photoperiod and temperature to synchronize their flowering with seasonal changes to maximize fitness. In the Arabidopsis photoperiodic flowering pathway, the circadian clock-regulated components, such as FLAVIN-BINDING, KELCH REPEAT, F-BOX 1 and CONSTANS, both of which have light-controlled functions, are crucial to induce the day-length specific expression of the FLOWERING LOCUS T (FT) gene in leaves. Recent advances indicate that FT transcriptional regulation is central for integrating the information derived from other important internal and external factors, such as developmental age, amount of gibberellic acid, and the ambient temperature. In this review, we describe how these factors interactively regulate the expression of FT, the main component of florigen, in leaves.
Elroy R. Cober
Full Text Available Soybean isolines with different combinations of photoperiod sensitivity alleles were planted in a greenhouse at different times during the year resulting in natural variation in daily incident irradiance and duration. The time from planting to first flower were observed. Mathematical models, using additive and multiplicative modes, were developed to quantify the effect of photoperiod, temperature, photoperiod-temperature interactions, rate of photoperiod change, and daily solar irradiance on flowering time. Observed flowering times correlated with predicted times (R2 = 0.92, Standard Error of the Estimate (SSE = 2.84 d, multiplicative mode; R2 = 0.91, SSE = 2.88 d, additive mode. The addition of a rate of photoperiod change function and an irradiance function to the temperature and photoperiod functions improved the accuracy of flowering time prediction. The addition of a modified photoperiod function, which allowed for photoperiod sensitivity at shorter photoperiods, improved prediction of flowering time. Both increasing and decreasing rate of photoperiod change, as well as low levels of daily irradiance delayed flowering in soybean. The complete model, which included terms for the rate of photoperiod change, photoperiod, temperature and irradiance, predicted time to first flower in soybean across a range of environmental conditions with an SEE of 3.6 days when tested with independent data.
Ionescu, Irina Alexandra
The timing of flowering is a well-researched but at the same time incredibly complex process in angiosperms. Although we are in possession of detailed knowledge on the genetic level of flowering time regulation in the model plant Arabidopsis thaliana, it is often difficult to transfer this knowle...... and its amide coincided with flowering time in both species. Taken together, these results contribute to elucidating parts of the complex network regulating flowering time in perennial plants.......The timing of flowering is a well-researched but at the same time incredibly complex process in angiosperms. Although we are in possession of detailed knowledge on the genetic level of flowering time regulation in the model plant Arabidopsis thaliana, it is often difficult to transfer...... this knowledge to other plants, like perennial woody plants growing in temperate regions. The main reason for this is a process called bud dormancy, which enables these plants to survive the harsh environmental conditions of winter. Accordingly a certain amount of cold is required for them to flower properly...
Terfa, Meseret Tesema; Solhaug, Knut Asbjørn; Gislerød, Hans Ragnar; Olsen, Jorunn Elisabeth; Torre, Sissel
Alterations in light quality affect plant morphogenesis and photosynthetic responses but the effects vary significantly between species. Roses exhibit an irradiance-dependent flowering control but knowledge on light quality responses is scarce. In this study we analyzed, the responses in morphology, photosynthesis and flowering of Rosa × hybrida to different blue (B) light proportions provided by light-emitting diodes (LED, high B 20%) and high pressure sodium (HPS, low B 5%) lamps. There was a strong morphological and growth effect of the light sources but no significant difference in total dry matter production and flowering. HPS-grown plants had significantly higher leaf area and plant height, yet a higher dry weight proportion was allocated to leaves than stems under LED. LED plants showed 20% higher photosynthetic capacity (Amax ) and higher levels of soluble carbohydrates. The increase in Amax correlated with an increase in leaf mass per unit leaf area, higher stomata conductance and CO2 exchange, total chlorophyll (Chl) content per area and Chl a/b ratio. LED-grown leaves also displayed a more sun-type leaf anatomy with more and longer palisade cells and a higher stomata frequency. Although floral initiation occurred at a higher leaf number in LED, the time to open flowers was the same under both light conditions. Thereby the study shows that a higher portion of B light is efficient in increasing photosynthesis performance per unit leaf area, enhancing growth and morphological changes in roses but does not affect the total Dry Matter (DM) production or time to open flower.
Johansson, Jacob; Bolmgren, Kjell; Jonzén, Niclas
Long-term phenology monitoring has documented numerous examples of changing flowering dates during the last century. A pivotal question is whether these phenological responses are adaptive or not under directionally changing climatic conditions. We use a classic dynamic growth model for annual plants, based on optimal control theory, to find the fitness-maximizing flowering time, defined as the switching time from vegetative to reproductive growth. In a typical scenario of global warming, with advanced growing season and increased productivity, optimal flowering time advances less than the start of the growing season. Interestingly, increased temporal spread in production over the season may either advance or delay the optimal flowering time depending on overall productivity or season length. We identify situations where large phenological changes are necessary for flowering time to remain optimal. Such changes also indicate changed selection pressures. In other situations, the model predicts advanced phenology on a calendar scale, but no selection for early flowering in relation to the start of the season. We also show that the optimum is more sensitive to increased productivity when productivity is low than when productivity is high. All our results are derived using a general, graphical method to calculate the optimal flowering time applicable for a large range of shapes of the seasonal production curve. The model can thus explain apparent maladaptation in phenological responses in a multitude of scenarios of climate change. We conclude that taking energy allocation trade-offs and appropriate time scales into account is critical when interpreting phenological patterns.
Full Text Available Flowering time is a key life-history trait in the plant life cycle. Most studies to unravel the genetics of flowering time in Arabidopsis thaliana have been performed under greenhouse conditions. Here, we describe a study about the genetics of flowering time that differs from previous studies in two important ways: first, we measure flowering time in a more complex and ecologically realistic environment; and, second, we combine the advantages of genome-wide association (GWA and traditional linkage (QTL mapping. Our experiments involved phenotyping nearly 20,000 plants over 2 winters under field conditions, including 184 worldwide natural accessions genotyped for 216,509 SNPs and 4,366 RILs derived from 13 independent crosses chosen to maximize genetic and phenotypic diversity. Based on a photothermal time model, the flowering time variation scored in our field experiment was poorly correlated with the flowering time variation previously obtained under greenhouse conditions, reinforcing previous demonstrations of the importance of genotype by environment interactions in A. thaliana and the need to study adaptive variation under natural conditions. The use of 4,366 RILs provides great power for dissecting the genetic architecture of flowering time in A. thaliana under our specific field conditions. We describe more than 60 additive QTLs, all with relatively small to medium effects and organized in 5 major clusters. We show that QTL mapping increases our power to distinguish true from false associations in GWA mapping. QTL mapping also permits the identification of false negatives, that is, causative SNPs that are lost when applying GWA methods that control for population structure. Major genes underpinning flowering time in the greenhouse were not associated with flowering time in this study. Instead, we found a prevalence of genes involved in the regulation of the plant circadian clock. Furthermore, we identified new genomic regions lacking
Full Text Available The paper presents results of eight-year study (1999-2006 of flowering phenophase in 21 introduced sweet cherry cultivars grown under the agro-environmental conditions of West Serbia. Flowering time, as well as progress and abundance of flowering were studied, and classification of the studied cultivars according to flowering time was derived. On the basis of mean several-year overlap in phenophase of full flowering and on the grounds of so far known data on classification of these cultivars among incompatibility groups, we have offered a recommendation for their cultivation in orchards whereby the most effective pollination and fertilization can be ensured as well as good fruit-set and satisfactory fruit yields.
Carbognani, Michele; Bernareggi, Giulietta; Perucco, Francesco; Tomaselli, Marcello; Petraglia, Alessandro
Alpine snowbed communities are among the habitats most threatened by climate change. The warmer temperature predicted, coupled with advanced snowmelt time, will influence flowering phenology, which is a key process in species adaptation to changing environmental conditions and plant population dynamics. However, we know little about the effects of changing micro-climate on flowering time in snowbeds and the mechanisms underlying such phenological responses. The flowering phenology of species inhabiting alpine snowbeds was assessed with weekly observations over five growing seasons. We analysed flowering time in relation to micro-climatic variation in snowmelt date, soil and air temperature, and experimental warming during the snow-free period. This approach allowed us to test hypotheses concerning the processes driving flowering phenology. The plants were finely tuned with inter-annual and intra-seasonal variations of their micro-climate, but species did not track the same micro-climatic feature to flower. At the growing-season time-scale, the air surrounding the plants was the most common trigger of the blooming period. However, at the annual time-scale, the snowmelt date was the main controlling factor for flowering time, even in warmer climate. Moreover, spatial patterns of the snowmelt influenced the developmental rate of the species because in later snowmelt sites the plants needed a lower level of heat accumulation to enter anthesis. Phenological responses to experimental warming differed among species, were proportional to the pre-flowering time-span of plants, and did not show consistent trends of change over time. Finally, warmer temperature produced an overall increase of flowering synchrony both within and among plant species.
Song, Kitae; Kim, Hyo Chul; Shin, Seungho; Kim, Kyung-Hee; Moon, Jun-Cheol; Kim, Jae Yoon; Lee, Byung-Moo
Flowering time is an important factor determining yield and seed quality in maize. A change in flowering time is a strategy used to survive abiotic stresses. Among abiotic stresses, drought can increase anthesis-silking intervals (ASI), resulting in negative effects on maize yield. We have analyzed the correlation between flowering time and drought stress using RNA-seq and bioinformatics tools. Our results identified a total of 619 genes and 126 transcripts whose expression was altered by drought stress in the maize B73 leaves under short-day condition. Among drought responsive genes, we also identified 20 genes involved in flowering times. Gene Ontology (GO) enrichment analysis was used to predict the functions of the drought-responsive genes and transcripts. GO categories related to flowering time included reproduction, flower development, pollen–pistil interaction, and post-embryonic development. Transcript levels of several genes that have previously been shown to affect flowering time, such as PRR37, transcription factor HY5, and CONSTANS, were significantly altered by drought conditions. Furthermore, we also identified several drought-responsive transcripts containing C2H2 zinc finger, CCCH, and NAC domains, which are frequently involved in transcriptional regulation and may thus have potential to alter gene expression programs to change maize flowering time. Overall, our results provide a genome-wide analysis of differentially expressed genes (DEGs), novel transcripts, and isoform variants expressed during the reproductive stage of maize plants subjected to drought stress and short-day condition. Further characterization of the drought-responsive transcripts identified in this study has the potential to advance our understanding of the mechanisms that regulate flowering time under drought stress.
Hori, Kiyosumi; Matsubara, Kazuki; Yano, Masahiro
Integration of previous Mendelian genetic analyses and recent molecular genomics approaches, such as linkage mapping and QTL cloning, dramatically strengthened our current understanding of genetic control of rice flowering time. Flowering time is one of the most important agronomic traits for seed production in rice (Oryza sativa L.). It is controlled mainly by genes associated with photoperiod sensitivity, particularly in short-day plants such as rice. Since the early twentieth century, rice breeders and researchers have been interested in elucidating the genetic basis of flowering time because its modification is important for regional adaptation and yield optimization. Although flowering time is a complex trait controlled by many quantitative trait loci (QTLs), classical genetic studies have shown that many associated genes are inherited in accordance with Mendelian laws. Decoding the rice genome sequence opened a new era in understanding the genetic control of flowering time on the basis of genome-wide mapping and gene cloning. Heading date 1 (Hd1) was the first flowering time QTL to be isolated using natural variation in rice. Recent accumulation of information on rice genome has facilitated the cloning of other QTLs, including those with minor effects on flowering time. This information has allowed us to rediscover some of the flowering genes that were identified by classical Mendelian genetics. The genes characterized so far, including Hd1, have been assigned to specific photoperiod pathways. In this review, we provide an overview of the studies that led to an in-depth understanding of the genetic control of flowering time in rice, and of the current state of improving and fine-tuning this trait for rice breeding.
Flowering time is one of the major adaptive traits in domestication of maize and an important selection criterion in breeding. To detect more maize flowering time variants we evaluated flowering time traits using an extremely large multi- genetic background population that contained more than 8000 l...
Xiao-Ming Zheng; Li Feng; Junrui Wang; Weihua Qiao; Lifang Zhang; Yunlian Cheng; Qingwen Yang
Due to the remarkable adaptability to various environments, rice varieties with diverse flowering times have been domesticated or improved from Oryza rufipogon. Detailed knowledge of the genetic factors controlling flower-ing time will facilitate understanding the adaptation mecha-nism in cultivated rice and enable breeders to design appropriate genotypes for distinct preferences. In this study, four genes (Hd1, DTH8, Ghd7 and OsPRR37) in a rice long-day suppression pathway were collected and sequenced in 154, 74, 69 and 62 varieties of cultivated rice (Oryza sativa) respectively. Under long-day conditions, varieties with non-functional alleles flowered significantly earlier than those with functional alleles. However, the four genes have different genetic effects in the regulation of flowering time: Hd1 and OsPRR37 are major genes that generally regulate rice flowering time for all varieties, while DTH8 and Ghd7 only regulate regional rice varieties. Geographic analysis and network studies suggested that the nonfunctional alleles of these suppression loci with regional adaptability were derived recently and independently. Alleles with regional adaptability should be taken into consideration for genetic improvement. The rich genetic variations in these four genes, which adapt rice to different environments, provide the flexi-bility needed for breeding rice varieties with diverse flowering times.
Deyan, Kong; Shoujun, Chen; Liguo, Zhou; Huan, Gao; Lijun, Luo; Zaochang, Liu
Rice flowering regulation is an extremely complex process, which is controlled by genetic factors and external environment. Photoperiodic regulatory pathway is pivotal to control flowering in rice, in which florigen genes Hd3a and RTF1 are at the core and they are regulated by upstream Hd1-dependent, Ehd1-dependent, as well as both Hd1- and Ehd1-independent pathways. The three pathways bring a variety of light signal information together to Hd3a and RTF1 for further integration, and then transmit the signals in the form of florigen to the downstream flowering related genes. In this review, we summarize the research progress of photoperiod regulated genes on flowering time in rice, including the photoreceptors and circadian rhythm genes, the florigens, its upstream, downstream and interacting genes. We hope to provide a reference for in-depth study of rice flowering regulation.
Engelhorn, Julia; Moreau, Fanny; Fletcher, Jennifer C; Carles, Cristel C
The morphological variability of the flower in angiosperms, combined with its relatively simple structure, makes it an excellent model to study cell specification and the establishment of morphogenetic patterns. Flowers are the products of floral meristems, which are determinate structures that generate four different types of floral organs before terminating. The precise organization of the flower in whorls, each defined by the identity and number of organs it contains, is controlled by a multi-layered network involving numerous transcriptional regulators. In particular, the AGAMOUS (AG) MADS domain-containing transcription factor plays a major role in controlling floral determinacy in Arabidopsis thaliana in addition to specifying reproductive organ identity. This study aims to characterize the genetic interactions between the ULTRAPETALA1 (ULT1) and LEAFY (LFY) transcriptional regulators during flower morphogenesis, with a focus on AG regulation. Genetic and molecular approaches were used to address the question of redundancy and reciprocal interdependency for the establishment of flower meristem initiation, identity and termination. In particular, the effects of loss of both ULT1 and LFY function were determined by analysing flower developmental phenotypes of double-mutant plants. The dependency of each factor on the other for activating developmental genes was also investigated in gain-of-function experiments. The ULT1 and LFY pathways, while both activating AG expression in the centre of the flower meristem, functioned independently in floral meristem determinacy. Ectopic transcriptional activation by ULT1 of AG and AP3, another gene encoding a MADS domain-containing flower architect, did not depend on LFY function. Similarly, LFY did not require ULT1 function to ectopically determine floral fate. The results indicate that the ULT1 and LFY pathways act separately in regulating identity and determinacy at the floral meristem. In particular, they independently
Fernández-Lozano, Antonia; Yuste-Lisbona, Fernando J; Pérez-Martín, Fernando; Pineda, Benito; Moreno, Vicente; Lozano, Rafael; Angosto, Trinidad
A novel tomato (Solanum lycopersicum L.) mutant affected in reproductive development, excessive number of floral organs (eno), is described in this study. The eno plants yielded flowers with a higher number of floral organs in the three innermost floral whorls and larger fruits than those found in wild-type plants. Scanning-electron microscopy study indicated that the rise in floral organ number and fruit size correlates with an increased size of floral meristem at early developmental stages. It has been reported that mutation at the FASCIATED (FAS) gene causes the development of flowers with supernumerary organs; however, complementation test and genetic mapping analyses proved that ENO is not an allele of the FAS locus. Furthermore, expression of WUSCHEL (SlWUS) and INHIBITOR OF MERISTEM ACTIVITY (IMA), the two main regulators of floral meristem activity in tomato, is altered in eno but not in fas flowers indicating that ENO could exert its function in the floral meristem independently of FAS. Interestingly, the eno mutation delayed the expression of IMA leading to a prolonged expression of SlWUS, which would explain the greater size of floral meristem. Taken together, results showed that ENO plays a significant role in the genetic pathway regulating tomato floral meristem development. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.
Guixia Xu; Hongzhi Kong
The process of flowering is controlled by a hierarchy of floral genes that act as flowering time genes, inflorescence/floral meristem identity genes, and/or floral organ-identity genes. The most important and well-characterized floral genes are those that belong to the MADS-box family of transcription factors. Compelling evidence suggests that floral MADS-box genes have experienced a few large-scale duplication events. In particular, the pre-core eudicot duplication events have been considered to correlate with the emergence and diversification of core eudicots. Duplication of floral MADS-box genes has also been documented in monocots, particularly in grasses, although a systematic study is lacking. In the present study, by conducting extensive phylogenetic analyses, we identified pre-Poaceae gene duplication events in each of the AP1, PI, AG, AGL11, AGL2/3/4, and AGL9gene lineages. Comparative genomic studies further indicated that some of these duplications actually resulted from the genome doubling event that occurred 66-70 million years ago (MYA). In addition, we found that after gene duplication, exonization (of intron sequences) and pseudoexonization (of exon sequences) have contributed to the divergence of duplicate genes in sequence structure and, possibly, gene function.
Marta Leonor Marulanda-ángel
Full Text Available Se desarrolló un protocolo de propagación in vitro a partir de meristemos florales para Heliconia bihai cv. Lobster Salmón. Para el efecto se establecieron 250 yemas florales en diferentes tiempos utilizando NaClO al 1% durante 20 min. El medio de establecimiento Murashige y Skoog con mejores resultados fue BAP (2 mg/lt, AIA (1 mg/lt y 0.1 g/lt de L-cisteína. La mayor produccion de brotes en multiplicación se obtuvo con 6 mg/lt de BAP y con un subcultivo posterior en medio con 2 mg/lt de BAP y 0.5 mg/lt de AIA, alcanzando una tasa de multiplicación de tres nuevas yemas. El enraizamiento de las plántulas in vitro se logró con 1.3 mg/lt de AIA. La aclimatación en vivero fue 92% de supervivencia. Se realizó un análisis de varianza (Anova y un test de Tukey para las variables evaluadas las cuales mostraron diferencias estadísticas en cada fase. La propagación in vitro de heliconias a partir de yemas florales requiere mayor tiempo en la fase de establecimiento y multiplicación, no obstante permite mayores porcentajes de supervivencia y una menor contaminación, ofreciendo material de siembra de diferentes especies de esta planta de interés comercial.A protocol for in vitro propagation of Heliconia bihai cv. Lobster Salmón was developed using flowering buds as initial explants. 250 flowering buds were established in different assays with NaClO at 1% during 20 minutes. The establishment in Murashige & Skoog's medium with BAP (2mg/L, AIA (1 mg/L and L-cystein (0.1 g/L showed the best results. Shoot multiplication was obtained with BAP (6 mg/L with a subsequent subculture in a medium with BAP (2 mg/L and AIA (0.5 mg/L, reaching multiplication rates of 3.0 new shoots. Rooting was achieved with AIA 1.3 mg/L. The survival rate during greenhouse acclimatization was 92%. Analysis of variance (ANOVA and Turkey's test were realized for each of the variables evaluated that showed statistical differences in all stages. The in vitro propagation of
Full Text Available A definição da época de semeadura é importante para culturas agrícolas de sequeiro. Em regiões tropicais há uma relação direta entre época de semeadura e desempenho do cultivo de mamona. O objetivo deste estudo foi avaliar a qualidade e o tamanho de sementes de mamona em função da época de semeadura e ordem floral. O experimento foi conduzido na Embrapa Clima Temperado em Pelotas, Rio Grande do Sul. Os materiais foram semeados em duas épocas: a primeira em novembro (entre os dias um e cinco e a segunda em dezembro (entre os dias um e cinco. Cada época teve 12 unidades experimentais em três blocos casualizados e o experimento constou de 72 parcelas, considerando-se as quatro cultivares, duas épocas de semeadura, três ordens florais e três repetições (4 x 2 x 3 x 3. A época de semeadura e a ordem floral influenciaram tanto a qualidade como o tamanho das sementes de mamona. A primeira época de semeadura proporcionou produção de sementes de melhor qualidade para as cultivares IAC 226, Al Guarany 2002 e BRS 188 Paraguaçu, enquanto a segunda época foi melhor para a IAC 80.The definition of sowing time is important for agricultural crops because it presents direct relationship with performance of these plants. The purpose of this study was to evaluate size and quality of castor seeds as function of sowing time and floral order, in the "EMBRAPA Clima Temperado" in Pelotas, Rio Grande do Sul State, Brazil. The materials were seeded in two times: the first in November (between days one and five and the second in December (between days one and five. Each sowing time had 12 units in a block randomized design with three blocks and 72 parcels, considering four cultivars, two periods of sowing, three floral orders and three replications (4 x 2 x 3 x 3. The time of sowing and the floral order influenced the quality and size of castor beans. The period of sowing allowed the production of seeds of better quality of the cultivars IAC Al
Dombrowski, Nina; Schlaeppi, Klaus; Agler, Matthew T; Hacquard, Stéphane; Kemen, Eric; Garrido-Oter, Ruben; Wunder, Jörg; Coupland, George; Schulze-Lefert, Paul
Recent field and laboratory experiments with perennial Boechera stricta and annual Arabidopsis thaliana suggest that the root microbiota influences flowering time. Here we examined in long-term time-course experiments the bacterial root microbiota of the arctic-alpine perennial Arabis alpina in natural and controlled environments by 16S rRNA gene profiling. We identified soil type and residence time of plants in soil as major determinants explaining up to 15% of root microbiota variation, whereas environmental conditions and host genotype explain maximally 11% of variation. When grown in the same soil, the root microbiota composition of perennial A. alpina is largely similar to those of its annual relatives A. thaliana and Cardamine hirsuta. Non-flowering wild-type A. alpina and flowering pep1 mutant plants assemble an essentially indistinguishable root microbiota, thereby uncoupling flowering time from plant residence time-dependent microbiota changes. This reveals the robustness of the root microbiota against the onset and perpetual flowering of A. alpina. Together with previous studies, this implies a model in which parts of the root microbiota modulate flowering time, whereas, after microbiota acquisition during vegetative growth, the established root-associated bacterial assemblage is structurally robust to perturbations caused by flowering and drastic changes in plant stature.
Full Text Available Cymbidium ensifolium belongs to the genus Cymbidium of the orchid family. Owing to its spectacular flower morphology, C. ensifolium has considerable ecological and cultural value. However, limited genetic data is available for this non-model plant, and the molecular mechanism underlying floral organ identity is still poorly understood. In this study, we characterize the floral transcriptome of C. ensifolium and present, for the first time, extensive sequence and transcript abundance data of individual floral organs. After sequencing, over 10 Gb clean sequence data were generated and assembled into 111,892 unigenes with an average length of 932.03 base pairs, including 1,227 clusters and 110,665 singletons. Assembled sequences were annotated with gene descriptions, gene ontology, clusters of orthologous group terms, the Kyoto Encyclopedia of Genes and Genomes, and the plant transcription factor database. From these annotations, 131 flowering-associated unigenes, 61 CONSTANS-LIKE (COL unigenes and 90 floral homeotic genes were identified. In addition, four digital gene expression libraries were constructed for the sepal, petal, labellum and gynostemium, and 1,058 genes corresponding to individual floral organ development were identified. Among them, eight MADS-box genes were further investigated by full-length cDNA sequence analysis and expression validation, which revealed two APETALA1/AGL9-like MADS-box genes preferentially expressed in the sepal and petal, two AGAMOUS-like genes particularly restricted to the gynostemium, and four DEF-like genes distinctively expressed in different floral organs. The spatial expression of these genes varied distinctly in different floral mutant corresponding to different floral morphogenesis, which validated the specialized roles of them in floral patterning and further supported the effectiveness of our in silico analysis. This dataset generated in our study provides new insights into the molecular mechanisms
Behdani, M. A.; Koocheki, A.; Nassiri, M.; Rezvani, P.
The objective of this study was to develop a thermal model that can be used for prediction of saffron flowering time. For this purpose, existing data on saffron flower emergence time were collected in a wide range of temperature regimes over the saffron production regions of Khorasan province, Iran. Linear second-order polynomial and 5-parameter beta models were used and statistically compared for their ability in predicting saffron flowering time as a function of temperature. The results showed a significant delay in flowering date across the temperature gradient. While beta model had a better statistical performance but the simple linear model also showed a good predicting ability and therefore, can be used as a reliable model.
Karunakaran, Gopalu; Jagathambal, Matheswaran; Kolesnikov, Evgeny; Dmitry, Arkhipov; Ishteev, Artur; Gusev, Alexander; Kuznetsov, Denis
Manganese oxide (Mn3O4) and iron oxide (Fe2O3) nanoparticles were successfully synthesized with the flower extracts of Chaenomeles sp. This is the first ever approach to synthesize nanoparticles from Chaenomeles sp. flower extracts. The organic molecules present in the flower extracts actively converted the nitrate precursor into its corresponding nanoparticles. The organic molecules that are involved in the synthesis of nanoparticles are identified using different phytochemical and gas chromatography-mass spectrometry analyses. The identified components are glycosides, alkaloids, terpenoids, saponins, flavonoids, quinines, and steroids. The structural and chemical compositions of the synthesized powder were also analyzed. The x-ray powder diffraction analysis revealed that the particles show tetragonal and rhombohedral crystalline phases. The Fourier transform infrared spectroscopy analysis showed the functional groups that are involved in the reduction of nitrates into the corresponding nanoparticles. Energy-dispersive x-ray spectroscopy analysis confirmed the presence of the elements in the synthesized nanoparticles. Transmission electron microscopy images showed the formation of spherical nanoparticles with an average size of 30-100 nm. Antioxidant analysis showed that the synthesized nanoparticles had excellent antioxidant potential. The antibacterial study showed that they inhibit the growth of harmful bacteria such as Pseudomonas aeruginosa and Streptococcus pyogenes. Thus, this study proposes a new eco-friendly and nontoxic method to synthesize nanoparticles for medicinal applications.
Endress, Peter K
In basal angiosperms (including ANITA grade, magnoliids, Choranthaceae, Ceratophyllaceae) almost all bisexual flowers are dichogamous (with male and female functions more or less separated in time), and nearly 100 per cent of those are protogynous (with female function before male function). Movements of floral parts and differential early abscission of stamens in the male phase are variously associated with protogyny. Evolution of synchronous dichogamy based on the day/night rhythm and anthesis lasting 2 days is common. In a few clades in Magnoliales and Laurales heterodichogamy has also evolved. Beetles, flies and thrips are the major pollinators, with various degrees of specialization up to large beetles and special flies in some large-flowered Nymphaeaceae, Magnoliaceae, Annonaceae and Aristolochiaceae. Unusual structural specializations are involved in floral biological adaptations (calyptras, inner staminodes, synandria and food bodies, and secretory structures on tepals, stamens and staminodes). Numerous specializations that are common in monocots and eudicots are absent in basal angiosperms. Several families are poorly known in their floral biology.
Endress, Peter K.
In basal angiosperms (including ANITA grade, magnoliids, Choranthaceae, Ceratophyllaceae) almost all bisexual flowers are dichogamous (with male and female functions more or less separated in time), and nearly 100 per cent of those are protogynous (with female function before male function). Movements of floral parts and differential early abscission of stamens in the male phase are variously associated with protogyny. Evolution of synchronous dichogamy based on the day/night rhythm and anthesis lasting 2 days is common. In a few clades in Magnoliales and Laurales heterodichogamy has also evolved. Beetles, flies and thrips are the major pollinators, with various degrees of specialization up to large beetles and special flies in some large-flowered Nymphaeaceae, Magnoliaceae, Annonaceae and Aristolochiaceae. Unusual structural specializations are involved in floral biological adaptations (calyptras, inner staminodes, synandria and food bodies, and secretory structures on tepals, stamens and staminodes). Numerous specializations that are common in monocots and eudicots are absent in basal angiosperms. Several families are poorly known in their floral biology. PMID:20047868
@@ Floral nectar, which is mainly composed of sugar, plays a major role in attracting pollinators. However, many studies show that most of the nectar also contains antiherbivore secondary compounds, such as phenolics, which could keep away some flower visitors.
Full Text Available the development and only the epidermis of the inner and outer integuments develops into a seed coat. A brief description of the vascularisation of the flower and its floral ontogeny is also given...
Trivellini, Alice; Cocetta, Giacomo; Hunter, Donald A.; Vernieri, Paolo; Ferrante, Antonio
Flowers are complex systems whose vegetative and sexual structures initiate and die in a synchronous manner. The rapidity of this process varies widely in flowers, with some lasting for months while others such as Hibiscus rosa-sinensis survive for only a day. The genetic regulation underlying these differences is unclear. To identify key genes and pathways that coordinate floral organ senescence of ephemeral flowers, we identified transcripts in H. rosa-sinensis floral organs by 454 sequencing. During development, 2053 transcripts increased and 2135 decreased significantly in abundance. The senescence of the flower was associated with increased abundance of many hydrolytic genes, including aspartic and cysteine proteases, vacuolar processing enzymes, and nucleases. Pathway analysis suggested that transcripts altering significantly in abundance were enriched in functions related to cell wall-, aquaporin-, light/circadian clock-, autophagy-, and calcium-related genes. Finding enrichment in light/circadian clock-related genes fits well with the observation that hibiscus floral development is highly synchronized with light and the hypothesis that ageing/senescence of the flower is orchestrated by a molecular clock. Further study of these genes will provide novel insight into how the molecular clock is able to regulate the timing of programmed cell death in tissues. PMID:27591432
Lohmann, J. U., and Weigel, D.
OAK-B135 Floral organ identity is controlled by combinatorial action of homeotic genes expressed in different territories within the emerging flower. This review discusses recent progress in our understanding of floral homeotic genes, with an emphasis on how their region-specific expression is regulated.
MUNIR Muhammad; JAMIL Muhammad; BALOCH Jalal-ud-din; KHATTAK Khalid Rehman
Shades of different light intensities (29%, 43%, 54%, 60% or 68%) along with control (no shade) were studied to observe their effects on the flowering time and plant quality. A hyperbolic relationship was observed between different light intensities under shade, and time to flowering. The total number of flower buds showed a curvilinear relationship with light intensities. Growth parameters related to the plant characteristics such as plant height, leaf area and plant fresh weight were improved under shading treatments at the expense of flowering time and number of flower buds. However, both linear and polynomial models applied assumed that cultivar Chimes White was equally sensitive to light intensity throughout development.
Full Text Available Chrysanthemum morifolium is an important floral crop that is cultivated worldwide. However, due to a lack of genomic resources, very little information is available concerning the molecular mechanisms of flower development in chrysanthemum.The transcriptomes of chrysanthemum vegetative buds, floral buds and buds were sequenced using Illumina paired-end sequencing technology. A total of 15.4 Gb of reads were assembled into 91,367 unigenes with an average length of 739 bp. A total of 43,137 unigenes showed similarity to known proteins in the Swissprot or NCBI non-redundant protein databases. Additionally, 25,424, 24,321 and 13,704 unigenes were assigned to 56 gene ontology (GO categories, 25 EuKaryotic Orthologous Groups (KOG categories, and 285 Kyoto Encyclopedia of Genes and Genomes (KEGG pathways, respectively. A total of 1,876 differentially expressed genes (DEGs (1,516 up-regulated, 360 down-regulated were identified between vegetative buds and floral buds, and 3,300 DEGs (1,277 up-regulated, 1,706 down-regulated were identified between floral buds and buds. Many genes encoding important transcription factors (e.g., AP2, MYB, MYC, WRKY, NAC and CRT as well as proteins involved in carbohydrate metabolism, protein kinase activity, plant hormone signal transduction, and the defense responses, among others, were considerably up-regulated in floral buds. Genes involved in the photoperiod pathway and flower organ determination were also identified. These genes represent important candidate genes for molecular cloning and functional analysis to study flowering regulation in chrysanthemum.This comparative transcriptome analysis revealed significant differences in gene expression and signaling pathway components between the vegetative buds, floral buds and buds of Chrysanthemum morifolium. A wide range of genes was implicated in regulating the phase transition from vegetative to reproductive growth. These results should aid researchers in the study of
Su, Yi-Ting; Chen, Jen-Chih; Lin, Chan-Pin
Floral symptoms caused by phytoplasma largely resemble floral reversion in other plants. Periwinkle leaf yellowing (PLY) phytoplasma and peanut witches'-broom (PnWB) phytoplasma caused different degrees of floral abnormalities on infected periwinkle plants. The PLY phytoplasma-infected plants exhibited floral discoloration, virescence, small flowers, and only occasionally full floral reversion. In contrast, PnWB phytoplasma frequently induced complete floral reversion and resulted in a witches'-broom symptom from the floral reversion. Although different degrees of floral symptoms were induced by these two phytoplasmas, the morphological disorders were similar to those of other plants carrying SEPALLATA mutations or gene silencing. Here, we compared expression levels of organ-identity-related genes and pigmentation genes during floral symptom development. Accumulation of phytoplasmas in malformed flowers and their closely surrounding leaves was also compared. In infected plants, transcript abundance of all examined organ identity genes and pigmentation genes was suppressed. Indeed, CrSEP3, a SEPALLALA3 ortholog, showed the greatest suppression among genes examined. Of the pigmentation genes, transcript reduction of chalcone synthase was most highly correlated with the loss in floral pigmentation. Floral symptom severities were associated with the accumulation of either phytoplasmas. Interestingly, both phytoplasmas accumulated to higher levels in malformed flowers than in their surrounding leaves. Many plant pathogens manipulate host plant development to their advantage. It is intriguing to see whether phytoplasmas alter floral development to increase their population.
Shibaya, Taeko; Hori, Kiyosumi; Ogiso-Tanaka, Eri; Yamanouchi, Utako; Shu, Koka; Kitazawa, Noriyuki; Shomura, Ayahiko; Ando, Tsuyu; Ebana, Kaworu; Wu, Jianzhong; Yamazaki, Toshimasa; Yano, Masahiro
Flowering time is one of the most important agronomic traits in rice (Oryza sativa L.), because it defines harvest seasons and cultivation areas, and affects yields. We used a map-based strategy to clone Heading date 18 (Hd18). The difference in flowering time between the Japanese rice cultivars Koshihikari and Hayamasari was due to a single nucleotide polymorphism within the Hd18 gene, which encodes an amine oxidase domain-containing protein and is homologous to Arabidopsis FLOWERING LOCUS D (FLD). The Hayamasari Hd18 allele and knockdown of Hd18 gene expression delayed the flowering time of rice plants regardless of the day-length condition. Structural modeling of the Hd18 protein suggested that the non-synonymous substitution changed protein stability and function due to differences in interdomain hydrogen bond formation. Compared with those in Koshihikari, the expression levels of the flowering-time genes Early heading date 1 (Ehd1), Heading date 3a (Hd3a) and Rice flowering locus T1 (RFT1) were lower in a near-isogenic line with the Hayamasari Hd18 allele in a Koshihikari genetic background. We revealed that Hd18 acts as an accelerator in the rice flowering pathway under both short- and long-day conditions by elevating transcription levels of Ehd1 Gene expression analysis also suggested the involvement of MADS-box genes such as OsMADS50, OsMADS51 and OsMADS56 in the Hd18-associated regulation of Ehd1 These results suggest that, like FLD, its rice homolog accelerates flowering time but is involved in rice flowering pathways that differ from the autonomous pathways in Arabidopsis.
Simon van Mourik
Full Text Available An intriguing phenomenon in plant development is the timing and positioning of lateral organ initiation, which is a fundamental aspect of plant architecture. Although important progress has been made in elucidating the role of auxin transport in the vegetative shoot to explain the phyllotaxis of leaf formation in a spiral fashion, a model study of the role of auxin transport in whorled organ patterning in the expanding floral meristem is not available yet. We present an initial simulation approach to study the mechanisms that are expected to play an important role. Starting point is a confocal imaging study of Arabidopsis floral meristems at consecutive time points during flower development. These images reveal auxin accumulation patterns at the positions of the organs, which strongly suggests that the role of auxin in the floral meristem is similar to the role it plays in the shoot apical meristem. This is the basis for a simulation study of auxin transport through a growing floral meristem, which may answer the question whether auxin transport can in itself be responsible for the typical whorled floral pattern. We combined a cellular growth model for the meristem with a polar auxin transport model. The model predicts that sepals are initiated by auxin maxima arising early during meristem outgrowth. These form a pre-pattern relative to which a series of smaller auxin maxima are positioned, which partially overlap with the anlagen of petals, stamens, and carpels. We adjusted the model parameters corresponding to properties of floral mutants and found that the model predictions agree with the observed mutant patterns. The predicted timing of the primordia outgrowth and the timing and positioning of the sepal primordia show remarkable similarities with a developing flower in nature.
Bera, Paramita; Mukherjee, Chiranjit; Mitra, Adinpunya
Floral scent composed of low molecular weight volatile organic compounds. The sweet fragrance of any evening blooming flower is dominated by benzenoid and terpenoid volatile compounds. Floral scent of Jasminum sambac (Oleaceae) includes three major benzenoid esters - benzylacetate, methylbenzoate, and methylsalicylate and three major terpene compounds viz. (E)-β-ocimene, linalool and α-farnesene. We analyzed concentrations and emission rates of benzenoids and terpenoids during the developmental stages of J. sambac flower. In addition to spatial emission from different floral parts, we studied the time-course mRNA accumulations of phenylalanine ammonia-lyase (PAL) and the two representative genes of terpenoid pathway, namely 1-deoxy-d-xylulose 5-phosphate reductoisomerase (DXR) and terpene synthase (TPS). Further, in vitro activities of several enzymes of phenylpropanoid/benzenoid pathway viz., PAL and acetyl-coenzyme A: benzylalcohol acetyltransferase (BEAT), S-adenosyl-l-methionine: benzoic acid carboxyl methyl transferase (BAMT) and S-adenosyl-l-methionine: salicylic acid carboxyl methyltransferase (SAMT) were studied. All the above enzyme activities along with the in vitro activities of DXR and TPS were found to follow a certain rhythm as observed in the emission of different benzenoid and terpenoid compounds. Linalool emission peaked after petal opening and coincided with maximal expression of JsTPS gene as evidenced from RT-PCR analyses (semi-quantitative). The maximum transcript accumulation of this gene was observed in flower petals, indicating that the petals of J. sambac flower play an important role as a major contributor of volatile precursors. The transcripts accumulation of JsDXR and JsTPS in different developmental stages and in different floral part showed that emissions of terpenoid volatiles in J. sambac flower are partially regulated at transcription levels. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.
Castède, Sophie; Campoy, José Antonio; Le Dantec, Loïck; Quero-García, José; Barreneche, Teresa; Wenden, Bénédicte; Dirlewanger, Elisabeth
The timing of flowering in perennial plants is crucial for their survival in temperate climates and is regulated by the duration of bud dormancy. Bud dormancy release and bud break depend on the perception of cumulative chilling during endodormancy and heat during the bud development. The objectives of this work were to identify candidate genes involved in dormancy and flowering processes in sweet cherry, their mapping in two mapping progenies 'Regina' × 'Garnet' and 'Regina' × 'Lapins', and to select those candidate genes which co-localized with quantitative trait loci (QTLs) associated with temperature requirements for bud dormancy release and flowering. Based on available data on flowering processes in various species, a list of 79 candidate genes was established. The peach and sweet cherry orthologs were identified and primers were designed to amplify sweet cherry candidate gene fragments. Based on the amplified sequences of the three parents of the mapping progenies, SNPs segregations in the progenies were identified. Thirty five candidate genes were genetically mapped in at least one of the two progenies and all were in silico mapped. Co-localization between candidate genes and QTLs associated with temperature requirements and flowering date were identified for the first time in sweet cherry. The allelic composition of the candidate genes located in the major QTL for heat requirements and flowering date located on linkage group 4 have a significant effect on these two traits indicating their potential use for breeding programs in sweet cherry to select new varieties adapted to putative future climatic conditions.
Endress, Peter K; Armstrong, Joseph E
Background and Aims Anaxagorea is the phylogenetically basalmost genus in the large tropical Annonaceae (custard apple family) of Magnoliales, but its floral structure is unknown in many respects. The aim of this study is to analyse evolutionarily interesting floral features in comparison with other genera of the Annonaceae and the sister family Eupomatiaceae. Methods Live flowers of Anaxagorea crassipetala were examined in the field with vital staining, liquid-fixed material was studied with scanning electron microscopy, and microtome section series were studied with light microscopy. In addition, herbarium material of two other Anaxagorea species was cursorily studied with the dissecting microscope. Key Results Floral phyllotaxis in Anaxagorea is regularly whorled (with complex whorls) as in all other Annonaceae with a low or medium number of floral organs studied so far (in those with numerous stamens and carpels, phyllotaxis becoming irregular in the androecium and gynoecium). The carpels are completely plicate as in almost all other Annonaceae. In these features Anaxagorea differs sharply from the sister family Eupomatiaceae, which has spiral floral phyllotaxis and ascidiate carpels. Flat stamens and the presence of inner staminodes differ from most other Annonaceae and may be plesiomorphic in Anaxagorea. However, the inner staminodes appear to be non-secretory in most Anaxagorea species, which differs from inner staminodes in other families of Magnoliales (Eupomatiaceae, Degeneriacae, Himantandraceae), which are secretory. Conclusions Floral phyllotaxis in Anaxagorea shows that there is no signature of a basal spiral pattern in Annonaceae and that complex whorls are an apomorphy not just for a part of the family but for the family in its entirety, and irregular phyllotaxis is derived. This and the presence of completely plicate carpels in Anaxagorea makes the family homogeneous and distinguishes it from the closest relatives in Magnoliales.
Full Text Available Floral reward is important in ecological and evolutionary perspectives and essential in pollination biology. For example, floral traits, nectar and pollen features are essential for understanding the functional ecology, the dynamics of pollen transport, competition for pollinator services, and patterns of specialization and generalization in plant–pollinator interactions. We believe to present a synthetic description in the field of floral reward in Ranunculaceae family important in pollination biology and indicating connections between ecological and evolutionary approaches. The links between insect visitors’ behaviour and floral reward type and characteristics exist. Ranunculaceae is a family of aboot 1700 species (aboot 60 genera, distributed worldwide, however the most abundant representatives are in temperate and cool regions of the northern and southern hemispheres. The flowers are usually radially symmetric (zygomorphic and bisexual, but in Aconitum, Aquilegia are bilaterally symmetric (zygomorphic. Most Ranunculaceae flowers offer no nectar, only pollen (e.g., Ranunculus, Adonis vernalis, Thalictrum, but numerous species create trophic niches for different wild pollinators (e.g. Osmia, Megachile, Bombus, Andrena (Denisow et al. 2008. Pollen is a source of protein, vitamins, mineral salts, organic acids and hormones, but the nutritional value varies greatly between different plant species. The pollen production can differ significantly between Ranunculacea species. The mass of pollen produced in anthers differ due to variations in the number of developed anthers. For example, interspecies differences are considerable, 49 anthers are noted in Aquilegia vulgaris, 70 anthers in Ranunculus lanuginosus, 120 in Adonis vernalis. A significant intra-species differences’ in the number of anthers are also noted (e.g. 41 to 61 in Aquilegia vulgaris, 23-45 in Ranunculus cassubicus. Pollen production can be up to 62 kg per ha for Ranunculus acer
Genetics of flowering time in bread wheat Triticum aestivum: complementary interaction between vernalization-insensitive and photoperiod-insensitive mutations imparts very early flowering habit to spring wheat
Sushil Kumar; Vishakha Sharma; Swati Chaudhary; Anshika Tyagi; Poonam Mishra; Anupama Priyadarshini; Anupam Singh
Time to flowering in the winter growth habit bread wheat is dependent on vernalization (exposure to cold conditions) and exposure to long days (photoperiod). Dominant Vrn-1 (Vrn-A1, Vrn-B1 and Vrn-D1) alleles are associated with vernalization-independent spring growth habit. The semidominant Ppd-D1a mutation confers photoperiod-insensitivity or rapid flowering in wheat under short day and long day conditions. The objective of this study was to reveal the nature of interaction between Vrn-1 and Ppd-D1a mutations (active alleles of the respective genes vrn-1 and Ppd-D1b). Twelve Indian spring wheat cultivars and the spring wheat landrace Chinese Spring were characterized for their flowering times by seeding them every month for five years under natural field conditions in New Delhi. Near isogenic Vrn-1 Ppd-D1 and Vrn-1 Ppd-D1a lines constructed in two genetic backgrounds were also phenotyped for flowering time by seeding in two different seasons. The wheat lines of Vrn-A1a Vrn-B1 Vrn-D1 Ppd-D1a, Vrn-A1a Vrn-B1 Ppd-D1a and Vrn-A1a Vrn-D1 Ppd-D1a (or Vrn-1 Ppd-D1a) genotypes flowered several weeks earlier than that of Vrn-A1a Vrn-B1 Vrn-D1 Ppd-D1b, Vrn-A1b Ppd-D1b and Vrn-D1 Ppd-D1b (or Vrn-1 Ppd-D1b) genotypes. The flowering time phenotypes of the isogenic vernalization-insensitive lines confirmed that Ppd-D1a hastened flowering by several weeks. It was concluded that complementary interaction between Vrn-1 and Ppd-D1a active alleles imparted super/very-early flowering habit to spring wheats. The early and late flowering wheat varieties showed differences in flowering time between short day and long day conditions. The flowering time in Vrn-1 Ppd-D1a genotypes was hastened by higher temperatures under long day conditions. The ambient air temperature and photoperiod parameters for flowering in spring wheat were estimated at 25°C and 12 h, respectively.
Baghi, R.; Helmig, D.; Guenther, A.; Duhl, T.; Daly, R.
order as isoprene emissions from oak trees, which are among the highest BVOC flowering period floral emissions observed from plants to date. These findings illustrate that during the relatively brief springtime flowering period, floral emissions constitute by far the most significant contribution to the BVOC flux from these tree species, some of which are leafless at this time. Experimental results were integrated into the MEGAN biogenic emission model and simulations were performed to estimate the contribution of floral BVOC emissions to the total urban BVOC flux during the spring flowering period. The floral BVOC emitted during this three-month simulation are equivalent to 11% of the integrated monoterpene flux for the Boulder urban area.
"Teaching Flowers" reflects on humanity's deep connections to horticulture by gathering varied thoughts from seminal writers in the field. In addition, this visual article draws attention to labor issues within the U.S. floral industry by documenting the author's exploration of flowers as social sculpture in New York City.
Perpetual flowering strawberries have great economic value to the fresh market industry. Floral initiation in strawberry is largely determined by photoperiod, temperature, and genetics. Commercially grown strawberries are generally classified as remontant (repeated or perpetual flowering, day neutr...
Du, Yiwei; He, Wei; Deng, Changwang; Chen, Xi; Gou, Lanming; Zhu, Fugui; Guo, Wei; Zhang, Jianfu; Wang, Tao
Flowering time is a critical trait for crops cultivated under various temperature/photoperiod conditions around the world. To understand better the flowering time of rice, we used the vector pTCK303 to produce several lines of RNAi knockdown transgenic rice and investigated their flowering times and other agronomic traits. Among them, the heading date of FRRP1-RNAi knockdown transgenic rice was 23-26 days earlier than that of wild-type plants. FRRP1 is a novel rice gene that encodes a C3HC4-type Really Interesting Novel Gene (RING) finger domain protein. In addition to the early flowering time, FRRP1-RNAi knockdown transgenic rice caused changes on an array of agronomic traits, including plant height, panicle length and grain length. We analyzed the expression of some key genes associated with the flowering time and other agronomic traits in the FRRP1-RNAi knockdown lines and compared with that in wild-type lines. The expression of Hd3a increased significantly, which was the key factor in the early flowering time. Further experiments showed that the level of histone H2B monoubiquitination (H2Bub1) was noticeably reduced in the FRRP1-RNAi knockdown transgenic rice lines compared with wild-type plants and MBP-FRRP1-F1 was capable of self-ubiquitination. The results indicate that Flowering Related RING Protein 1 (FRRP1) is involved in histone H2B monoubiquitination and suggest that FRRP1 functions as an E3 ligase in vivo and in vitro. In conclusion, FRRP1 probably regulates flowering time and yield potential in rice by affecting histone H2B monoubiquitination, which leads to changes in gene expression in multiple processes.
Pollination by deceit in Myristica insipida, a beetle-pollinated nutmeg, was hypothesized to operate on intersexual differences in flower production and longevity, producing a daily fluctuation between floral display maxima and minima. Sticky traps were used to continuously monitor beetle activity. Flower production and naturally occurring intersexual differences in display were recorded. Male and female trees flowered in synchrony producing daily display maxima at 1800-0600 and display minima at 1400-1800. Rewarding male trees produced three times the number of flowers of female trees, but the greater longevity of female flowers reduced the intersexual difference in display maxima to a factor of two. There was no intersexual difference in display minima. Beetles were demonstrated to be sensitive to differences in both maximum and minimum displays on rewarding male trees, a necessary prerequisite for directional selection on display size. Beetle captures were significantly higher at male trees during floral display maxima, and no intersexual differences in capture rate occurred during floral display minima. However, capture rates at male trees did not decline as predicted, and the pattern of captures was consistent with crepuscular activity. Beetle captures at male and female trees were lower from 1800 to 0600 and 1000 to 1400, and higher from 0600 to 1000 and 1400 to 1800, but the differences were only significant at female trees. These data suggests that foraging errors are numerous, frequent, and the result of overall foraging activity.
Cao, Dong; Li, Ying; Wang, Jialin; Nan, Haiyang; Wang, Youning; Lu, Sijia; Jiang, Qiong; Li, Xiaoming; Shi, Danning; Fang, Chao; Yuan, Xiaohui; Zhao, Xiaohui; Li, Xia; Liu, Baohui; Kong, Fanjiang
Soybean [Glycine max (L.) Merr.] is an important crop used for human consumption, animal feed and biodiesel fuel. Wering time and maturity significantly affect soybean grain yield. In Arabidopsis thaliana, miR156 has been proposed to regulate the transition from the juvenile to the adult phase of shoot development, which is accompanied by changes in vegetative morphology and an increase in reproductive potential. However, the molecular mechanisms underlying miR156 function in soybean flowering remain unknown. Here, we report that the overexpression of GmmiR156b delays flowering time in soybean. GmmiR156b may target SPL orthologs and negatively regulate GmSPLs, thereby delaying flowering in soybean under LD and natural conditions. GmmiR156b down-regulates several known flowering time regulators in soybean, such as GmAP1 (a, b, c), GmLFY2, GmLFY2, GmFULs, GmSOC1s, GmFT5a, and GmmiR172. These data show that a similar miR156-SPL regulatory module was conserved in the soybean flowering pathway. However, GmFULs, GmSOC1a and GmSOC1b were significantly suppressed under LD conditions but not under SD conditions, which is different in Arabidopsis that these genes were down-regulated irrespective of photoperiod. In addition, GmmiR156b was up-regulated by E1, E2 (GmGI), E3 and E4, which control flowering time and maturity in soybean, and suppressed E1 (E1-Like) and E2 (E2-Like) genes under LD conditions. These data indicated that the miR156-SPL regulatory module was also with some degree of divergent in soybean flowering pathway.
Zeevaart, Jan A D
Florigen is the hypothetical leaf-produced signal that induces floral initiation at the shoot apex. The nature of florigen has remained elusive for more than 70 years. But recent progress toward understanding the regulatory network for flowering in Arabidopsis has led to the suggestion that FLOWERING LOCUS T (FT) or its product is the mobile flower-inducing signal that moves from an induced leaf through the phloem to the shoot apex. In the past year, physical and chemical evidence has shown that it is FT protein, and not FT mRNA, that moves from induced leaves to the apical meristem. These results have established that FT is the main, if not the only, component of the universal florigen.
S. G. Kashikar
Full Text Available Floral heteromorphism induced in Petunia hybrida with several chemical mutagens and gamma-radiation is discussed. Potentials of these mutagens in inducing various forms are described. The effect of heteromorphism on flower production, pollen sterility and seed set besides cross and self compatibilities between different heteromorphic forms have also been reported.
Full Text Available Most flowers display distinct colour patterns comprising two different areas. The peripheral large-area component of floral colour patterns attracts flower visitors from some distance and the central small-area component guides flower visitors towards landing sites. Whereas the peripheral colour is largely variable among species, the central colour, produced mostly by anthers and pollen or pollen mimicking floral guides, is predominantly yellow and UV-absorbing. This holds also for yellow flowers that regularly display a UV bull's eye pattern. Here we show that yellow-flowering Crocus species are a noticeable exception, since yellow-flowering Crocus species-being entirely UV-absorbing-exhibit low colour contrast between yellow reproductive organs and yellow tepals. The elongated yellow or orange-yellow style of Crocus flowers is a stamen-mimicking structure promoting cross-pollination by facilitating flower visitors' contact with the apical stigma before the flower visitors are touching the anthers. Since Crocus species possess either yellow, violet or white tepals, the colour contrast between the stamen-mimicking style and the tepals varies among species. In this study comprising 106 Crocus species, it was tested whether the style length of Crocus flowers is dependent on the corolla colour. The results show that members of the genus Crocus with yellow tepals have evolved independently up to twelve times in the genus Crocus and that yellow-flowering Crocus species possess shorter styles as compared to violet- and white-flowering ones. The manipulation of flower visitors by anther-mimicking elongated styles in Crocus flowers is discussed.
Lunau, Klaus; Konzmann, Sabine; Bossems, Jessica; Harpke, Doerte
Most flowers display distinct colour patterns comprising two different areas. The peripheral large-area component of floral colour patterns attracts flower visitors from some distance and the central small-area component guides flower visitors towards landing sites. Whereas the peripheral colour is largely variable among species, the central colour, produced mostly by anthers and pollen or pollen mimicking floral guides, is predominantly yellow and UV-absorbing. This holds also for yellow flowers that regularly display a UV bull's eye pattern. Here we show that yellow-flowering Crocus species are a noticeable exception, since yellow-flowering Crocus species-being entirely UV-absorbing-exhibit low colour contrast between yellow reproductive organs and yellow tepals. The elongated yellow or orange-yellow style of Crocus flowers is a stamen-mimicking structure promoting cross-pollination by facilitating flower visitors' contact with the apical stigma before the flower visitors are touching the anthers. Since Crocus species possess either yellow, violet or white tepals, the colour contrast between the stamen-mimicking style and the tepals varies among species. In this study comprising 106 Crocus species, it was tested whether the style length of Crocus flowers is dependent on the corolla colour. The results show that members of the genus Crocus with yellow tepals have evolved independently up to twelve times in the genus Crocus and that yellow-flowering Crocus species possess shorter styles as compared to violet- and white-flowering ones. The manipulation of flower visitors by anther-mimicking elongated styles in Crocus flowers is discussed.
Andargie, Mebeasealassie; Pasquet, Remy S; Muluvi, Geoffrey M; Timko, Michael P
Flowering time is a major adaptive trait in plants and an important selection criterion in the breeding for genetic improvement of crop species. QTLs for the time of flower opening and days to flower were identified in a cross between a short duration domesticated cowpea (Vigna unguiculata (L.) Walp.) variety, 524B, and a relatively long duration wild accession, 219-01. A set of 159 F7 lines was grown under greenhouse conditions and scored for the flowering time associated phenotypes of time of flower opening and days to flower. Using a LOD threshold of 2.0, putative QTLs were identified and placed on a linkage map consisting of 202 SSR markers and four morphological loci. A total of five QTLs related to the time of flower opening were identified, accounting for 8.8%-29.8% of the phenotypic variation. Three QTLs for days to flower were detected, accounting for 5.7%-18.5% of the phenotypic variation. The major QTL of days to flower and time of flower opening were both mapped on linkage group 1. The QTLs identified in this study provide a strong foundation for further validation and fine mapping for developing an efficient way to restrain the gene flow between the cultivated and wild plants.
Dyer, Adrian G; Whitney, Heather M; Arnold, Sarah E J; Glover, Beverley J; Chittka, Lars
Floral colour signals are used by pollinators as predictors of nutritional rewards, such as nectar. But as insect pollinators often need to invest energy to maintain their body temperature above the ambient temperature, floral heat might also be perceived as a reward. Here we show that bumblebees (Bombus terrestris) prefer to visit warmer flowers and that they can learn to use colour to predict floral temperature before landing. In what could be a widespread floral adaptation, plants may modulate their temperature to encourage pollinators to visit.
Ballerini Evangeline S
Full Text Available Abstract Background Flowering is a critical transition in plant development, the timing of which can have considerable fitness consequences. Until recently, research into the genetic control of flowering time and its associated developmental changes was focused on core eudicots (for example, Arabidopsis or monocots (for example, Oryza. Here we examine the flowering response of Aquilegia formosa, a member of the eudicot order Ranunculales that is emerging as an important model for the investigation of plant ecology and evolution. Results We have determined that A. formosa has a strong vernalization requirement but little or no photoperiod response, making it a day neutral (DN plant. Consistent with this, the Aquilegia homolog of FLOWERING LOCUS T (AqFT is expressed in both long and short days but surprisingly, the locus is expressed before the transition to flowering. In situ hybridizations with homologs of several Arabidopsis Floral Pathway Integrators (FPIs do not suggest conserved functions relative to Arabidopsis, the potential exceptions being AqLFY and AqAGL24.2. Conclusions In Aquilegia, vernalization is critical to flowering but this signal is not strictly required for the transcriptional activation of AqFT. The expression patterns of AqLFY and AqAGL24.2 suggest a hypothesis for the development of Aquilegia's determinate inflorescence whereby their differential expression controls the progression of each meristem from inflorescence to floral identity. Interestingly, none of the Aquilegia expression patterns are consistent with a function in floral repression which, combined with the lack of a FLC homolog, means that new candidate genes must be identified for the control of vernalization response in Aquilegia.
Full Text Available Plants produce nectar in their flowers as a reward for their pollinators and most of our crops depend on insect pollination, but little is known on the physiological control of nectar secretion. Jasmonates are well-known for their effects on senescence, the development and opening of flowers and on plant defences such as extrafloral nectar. Their role in floral nectar secretion has, however, not been explored so far. We investigated whether jasmonates have an influence on floral nectar secretion in oil-seed rape, Brassica napus. The floral tissues of this plant produced jasmonic acid (JA endogenously, and JA concentrations peaked shortly before nectar secretion was highest. Exogenous application of JA to flowers induced nectar secretion, which was suppressed by treatment with phenidone, an inhibitor of JA synthesis. This effect could be reversed by additional application of JA. Jasmonoyl-isoleucine and its structural mimic coronalon also increased nectar secretion. Herbivory or addition of JA to the leaves did not have an effect on floral nectar secretion, demonstrating a functional separation of systemic defence signalling from reproductive nectar secretion. Jasmonates, which have been intensively studied in the context of herbivore defences and flower development, have a profound effect on floral nectar secretion and, thus, pollination efficiency in B. napus. Our results link floral nectar secretion to jasmonate signalling and thereby integrate the floral nectar secretion into the complex network of oxylipid-mediated developmental processes of plants.
Full Text Available Abstract Background The Floral Genome Project was initiated to bridge the genomic gap between the most broadly studied plant model systems. Arabidopsis and rice, although now completely sequenced and under intensive comparative genomic investigation, are separated by at least 125 million years of evolutionary time, and cannot in isolation provide a comprehensive perspective on structural and functional aspects of flowering plant genome dynamics. Here we discuss new genomic resources available to the scientific community, comprising cDNA libraries and Expressed Sequence Tag (EST sequences for a suite of phylogenetically basal angiosperms specifically selected to bridge the evolutionary gaps between model plants and provide insights into gene content and genome structure in the earliest flowering plants. Results Random sequencing of cDNAs from representatives of phylogenetically important eudicot, non-grass monocot, and gymnosperm lineages has so far (as of 12/1/04 generated 70,514 ESTs and 48,170 assembled unigenes. Efficient sorting of EST sequences into putative gene families based on whole Arabidopsis/rice proteome comparison has permitted ready identification of cDNA clones for finished sequencing. Preliminarily, (i proportions of functional categories among sequenced floral genes seem representative of the entire Arabidopsis transcriptome, (ii many known floral gene homologues have been captured, and (iii phylogenetic analyses of ESTs are providing new insights into the process of gene family evolution in relation to the origin and diversification of the angiosperms. Conclusion Initial comparisons illustrate the utility of the EST data sets toward discovery of the basic floral transcriptome. These first findings also afford the opportunity to address a number of conspicuous evolutionary genomic questions, including reproductive organ transcriptome overlap between angiosperms and gymnosperms, genome-wide duplication history, lineage
Albert, Victor A; Soltis, Douglas E; Carlson, John E; Farmerie, William G; Wall, P Kerr; Ilut, Daniel C; Solow, Teri M; Mueller, Lukas A; Landherr, Lena L; Hu, Yi; Buzgo, Matyas; Kim, Sangtae; Yoo, Mi-Jeong; Frohlich, Michael W; Perl-Treves, Rafael; Schlarbaum, Scott E; Bliss, Barbara J; Zhang, Xiaohong; Tanksley, Steven D; Oppenheimer, David G; Soltis, Pamela S; Ma, Hong; dePamphilis, Claude W; Leebens-Mack, James H
Background The Floral Genome Project was initiated to bridge the genomic gap between the most broadly studied plant model systems. Arabidopsis and rice, although now completely sequenced and under intensive comparative genomic investigation, are separated by at least 125 million years of evolutionary time, and cannot in isolation provide a comprehensive perspective on structural and functional aspects of flowering plant genome dynamics. Here we discuss new genomic resources available to the scientific community, comprising cDNA libraries and Expressed Sequence Tag (EST) sequences for a suite of phylogenetically basal angiosperms specifically selected to bridge the evolutionary gaps between model plants and provide insights into gene content and genome structure in the earliest flowering plants. Results Random sequencing of cDNAs from representatives of phylogenetically important eudicot, non-grass monocot, and gymnosperm lineages has so far (as of 12/1/04) generated 70,514 ESTs and 48,170 assembled unigenes. Efficient sorting of EST sequences into putative gene families based on whole Arabidopsis/rice proteome comparison has permitted ready identification of cDNA clones for finished sequencing. Preliminarily, (i) proportions of functional categories among sequenced floral genes seem representative of the entire Arabidopsis transcriptome, (ii) many known floral gene homologues have been captured, and (iii) phylogenetic analyses of ESTs are providing new insights into the process of gene family evolution in relation to the origin and diversification of the angiosperms. Conclusion Initial comparisons illustrate the utility of the EST data sets toward discovery of the basic floral transcriptome. These first findings also afford the opportunity to address a number of conspicuous evolutionary genomic questions, including reproductive organ transcriptome overlap between angiosperms and gymnosperms, genome-wide duplication history, lineage-specific gene duplication and
Wong, Chui E; Singh, Mohan B; Bhalla, Prem L
Flowering process governs seed set and thus affects agricultural productivity. Soybean, a major legume crop, requires short-day photoperiod conditions for flowering. While leaf-derived signal(s) are essential for the photoperiod-induced floral initiation process at the shoot apical meristem, molecular events associated with early floral transition stages in either leaves or shoot apical meristems are not well understood. To provide novel insights into the molecular basis of floral initiation, RNA-Seq was used to characterize the soybean transcriptome of leaf and micro-dissected shoot apical meristem at different time points after short-day treatment. Shoot apical meristem expressed a higher number of transcripts in comparison to that of leaf highlighting greater diversity and abundance of transcripts expressed in the shoot apical meristem. A total of 2951 shoot apical meristem and 13,609 leaf sequences with significant profile changes during the time course examined were identified. Most changes in mRNA level occurred after 1short-day treatment. Transcripts involved in mediating responses to stimulus including hormones or in various metabolic processes represent the top enriched GO functional category for the SAM and leaf dataset, respectively. Transcripts associated with protein degradation were also significantly changing in leaf and SAM implicating their involvement in triggering the developmental switch. RNA-Seq analysis of shoot apical meristem and leaf from soybean undergoing floral transition reveal major reprogramming events in leaves and the SAM that point toward hormones gibberellins (GA) and cytokinin as key regulators in the production of systemic flowering signal(s) in leaves. These hormones may form part of the systemic signals in addition to the established florigen, FLOWERING LOCUS T (FT). Further, evidence is emerging that the conversion of shoot apical meristem to inflorescence meristem is linked with the interplay of auxin, cytokinin and GA
Chui E Wong
Full Text Available Flowering process governs seed set and thus affects agricultural productivity. Soybean, a major legume crop, requires short-day photoperiod conditions for flowering. While leaf-derived signal(s are essential for the photoperiod-induced floral initiation process at the shoot apical meristem, molecular events associated with early floral transition stages in either leaves or shoot apical meristems are not well understood. To provide novel insights into the molecular basis of floral initiation, RNA-Seq was used to characterize the soybean transcriptome of leaf and micro-dissected shoot apical meristem at different time points after short-day treatment. Shoot apical meristem expressed a higher number of transcripts in comparison to that of leaf highlighting greater diversity and abundance of transcripts expressed in the shoot apical meristem. A total of 2951 shoot apical meristem and 13,609 leaf sequences with significant profile changes during the time course examined were identified. Most changes in mRNA level occurred after 1short-day treatment. Transcripts involved in mediating responses to stimulus including hormones or in various metabolic processes represent the top enriched GO functional category for the SAM and leaf dataset, respectively. Transcripts associated with protein degradation were also significantly changing in leaf and SAM implicating their involvement in triggering the developmental switch. RNA-Seq analysis of shoot apical meristem and leaf from soybean undergoing floral transition reveal major reprogramming events in leaves and the SAM that point toward hormones gibberellins (GA and cytokinin as key regulators in the production of systemic flowering signal(s in leaves. These hormones may form part of the systemic signals in addition to the established florigen, FLOWERING LOCUS T (FT. Further, evidence is emerging that the conversion of shoot apical meristem to inflorescence meristem is linked with the interplay of auxin
Andersen, D.C.; Nelson, S.M.
Climate change projections for semiarid and arid North America include reductions in stream discharge that could adversely affect riparian plant species dependent on stream-derived ground water. In order to better understand this potential impact, we used a space-for-time substitution to test the hypotheses that increasing depth-to-groundwater (DGW) is inversely related to Tamarix sp. (saltcedar) flower abundance (F) and nectar production per flower (N). We also assessed whether DGW affected the richness or abundance of insects visiting flowers. We examined Tamarix floral attributes and insect visitation patterns during 2010 and 2011 at three locations along a deep DWG gradient (3.2–4.1 m) on a floodplain terrace adjacent to Las Vegas Wash, an effluent-dominated Mojave Desert stream. Flower abundance and insect visitation patterns differed between years, but no effect from DGW on either F or N was detected. An eruption of a novel non-native herbivore, the splendid tamarisk weevil (Coniatus splendidulus), likely reduced flower production in 2011.
Effect of nectar pillaging by native stingless bees (Hymenoptera: Apidae in the abscission of flowers of Bougainvillea spectabilis Willd. (Nyctaginaceae =Efeito da pilhagem de néctar por abelhas nativas sem ferrão (Hymenoptera: Apidae na abscisão floral de Bougainvillea spectabilis Willd. (Nyctaginaceae
Full Text Available This study had as objective to evaluate whether the pillaging activity by native bees influences floral abscission. Samples were collected in ten individuals of Bougainvillea spectabilis. In the period between May 4 and June 1st, 2009, 2,874 flowers were collected on the ground and 2,895 from the plants, with three-day intervals between each collection and a total of 10 repetitions in each plant. We measured the total of closed flowers, open flowers, robbed flowers, normal flowers, open robbed flowers and nonrobber open flowers, in both soil and plant. For the statistical analysis, the T-test was used to see whether there was a difference between the averages obtained from the evaluated characteristics between the soil flowers and plant flowers. Simple linear regression was used to see whether there was a relationship between the closed flowers and robbed closed flowers found on the ground and open flowers and non-robbed open flowers in the plant. There were significant differences regarding all variables measured between soil and plant.A correlation was found at both closed flowers and robbed closed flowers found on the ground and open flowers and non-robbed open flowers in the plant.O presente trabalho teve como objetivo avaliar a atividade de pilhagemde abelhas nativas influenciando a abscisão floral de Bougainvillea spectabilis. As coletas foram realizadas em dez indivíduos de B. spectabilis. Foram coletadas 2.874 flores no solo e 2.895 na planta no período de 4/5/2009 a 1/6/2009 com intervalo de três dias entre cada coleta, totalizando 10 repetições em cada indivíduo. Foram mensuradas as flores fechadas, flores abertas, flores fechadas pilhadas, flores fechadas não pilhadas, flores abertas pilhadas e flores abertas não pilhadas tanto no solo como na planta. Para as análises estatísticas foi utilizado o Teste-T para verificar se houve diferença entre as médias obtidas das características avaliadas entre as flores do solo e as
CaraDonna, Paul J; Iler, Amy M; Inouye, David W
Phenology--the timing of biological events--is highly sensitive to climate change. However, our general understanding of how phenology responds to climate change is based almost solely on incomplete assessments of phenology (such as first date of flowering) rather than on entire phenological distributions. Using a uniquely comprehensive 39-y flowering phenology dataset from the Colorado Rocky Mountains that contains more than 2 million flower counts, we reveal a diversity of species-level phenological shifts that bring into question the accuracy of previous estimates of long-term phenological change. For 60 species, we show that first, peak, and last flowering rarely shift uniformly and instead usually shift independently of one another, resulting in a diversity of phenological changes through time. Shifts in the timing of first flowering on average overestimate the magnitude of shifts in the timing of peak flowering, fail to predict shifts in the timing of last flowering, and underrepresent the number of species changing phenology in this plant community. Ultimately, this diversity of species-level phenological shifts contributes to altered coflowering patterns within the community, a redistribution of floral abundance across the season, and an expansion of the flowering season by more than I mo during the course of our study period. These results demonstrate the substantial reshaping of ecological communities that can be attributed to shifts in phenology.
Teixido, Alberto L.; Méndez, Marcos; Valladares, Fernando
Plants with larger and longer-lived flowers receive more pollinator visits and increase reproductive success, though may also suffer more from antagonistic interactions with animals. Florivores can reduce fruit and seed production, so selection on flower size, floral longevity and/or number of flowers may thus be determined by the relative effects of both pollinators and florivores. In this study flowers of Cistus ladanifer, a large-flowered Mediterranean shrub, were monitored to evaluate the effects of flower size, floral longevity and number of flowers on levels of florivory in four populations. Number of flowers was variable but did not differ among populations. Both flower size and floral longevity of C. ladanifer showed broad variation and significantly differed among populations. Overall, 7% of flowers suffered attack by florivores, which were mainly ants picking the stamens and beetles consuming petals and pollen. Within-populations, larger and longer-lived flowers tended to be affected by florivores more frequently. The low overall incidence of florivores and its lack of between-population variation suggest that florivory may not influence intraspecific variation of these floral traits. However, moderate florivory levels on the largest and longest-lived flowers open the possibility of exerting selection towards smaller and shorter-lived flowers in some of the populations studied.
Rantanen, Marja; Kurokura, Takeshi; Jiang, Panpan; Mouhu, Katriina; Hytönen, Timo
Photoperiod and temperature are major environmental signals affecting flowering in plants. Although molecular pathways mediating these signals have been well characterized in the annual model plant Arabidopsis, much less information is known in perennials. Many perennials including the woodland strawberry (Fragaria vesca L.) are induced to flower in response to decreasing photoperiod and temperature in autumn and they flower following spring. We showed earlier that, in contrast with Arabidopsis, the photoperiodic induction of flowering in strawberry occurs in short days (SD) when the decrease in FvFT1 (flowering locus T) and FvSOC1 (suppressor of the overexpression of constans1) expression leads to lower mRNA levels of the floral repressor, FvTFL1 (terminal flower1). By using transgenic lines and gene expression analyses, we show evidence that the temperature-mediated changes in the FvTFL1 mRNA expression set critical temperature limits for the photoperiodic flowering in strawberry. At temperatures below 13 °C, low expression level of FvTFL1 in both SD and long days (LD) allows flower induction to occur independently of the photoperiod. Rising temperature gradually increases FvTFL1 mRNA levels under LD, and at temperatures above 13 °C, SD is required for the flower induction that depends on the deactivation of FvSOC1 and FvTFL1. However, an unknown transcriptional activator, which functions independently of FvSOC1, enhances the expression of FvTFL1 at 23 °C preventing photoperiodic flowering. We suggest that the observed effect of the photoperiod × temperature interaction on FvTFL1 mRNA expression may allow strawberry to induce flowers in correct time in different climates.
Full Text Available The study was conducted during 2010 in marigold (Calendula officinalis L. to determine the effects of three plant densities (plant density A - 65 cm x 35 cm; plant density B - 65 cm x 25 cm; plant density C – 55 cm x 25 cm and harvest time on the number, weight and diameter of marigold flowers. The results showed that the plant density significantly influenced the number of flowers per plant and flower weight. The largest number of flowers per plant was recorded in the plant density B (13.2 and the lowest (9.87 in the plant density C. The lowest flower weight was recorded in the plant density C (1.31 g and was statistically lower than the flower weight in the plant densities A (1.42 g and B (1.38 g. The plant density significantly influenced the number of flowers on side branches, being the highest in the plant density B. The diameter of the marigold flower was not significantly influenced by the plant density. During the experiment, a total of 13 harvests were achieved. The greatest number of flowers per plant was harvested in the eighth, ninth and tenth harvest, while the largest flower weight was measured in the fifth and twelfth harvest. On the average, the number of flowers per plant / harvest was 11.63 and the weight of flowers was 1.38 g. Diameter of marigold flowers ranged from 2.89 cm to 3.59 cm in the thirteenth and the third harvest, respectively. The number of flowers on side branches per plant / harvest was 11.61.
Yulan; KUANG; Qifang; LI; Wangyun; NING
Cut flower production in Yunnan accounts for 80%nationwide.In order to expand the Yunnan Flower sales channels,the promotion of the development of e-commerce is necessary.In 2012 China’s online shopping users reached 247 million people,but e-commerce of fresh flowers lagged behind due to the constraints of preservation facilities and logistics cost.The analysis of the factors restricting the development of floral e-commerce and the proposition of solutions to this problem can promote faster development of Yunnan floral e-commerce.
Full Text Available Abstract Background The ability to control the timing of flowering is a key strategy for planning production in ornamental species such as azalea, however it requires a thorough understanding of floral transition. Floral transition is achieved through a complex genetic network and regulated by multiple environmental and endogenous cues. Dynamic changes between chromatin states facilitating or inhibiting DNA transcription regulate the expression of floral induction pathways in response to environmental and developmental signals. DNA methylation and histone modifications are involved in controlling the functional state of chromatin and gene expression. Results The results of this work indicate that epigenetic mechanisms such as DNA methylation and histone H4 acetylation have opposite and particular dynamics during the transition from vegetative to reproductive development in the apical shoots of azalea. Global levels of DNA methylation and histone H4 acetylation as well as immunodetection of 5-mdC and acetylated H4, in addition to a morphological study have permitted the delimitation of four basic phases in the development of the azalea bud and allowed the identification of a stage of epigenetic reprogramming which showed a sharp decrease of whole DNA methylation similar to that is defined in other developmental processes in plants and in mammals. Conclusion The epigenetic control and reorganization of chromatin seem to be decisive for coordinating floral development in azalea. DNA methylation and H4 deacetylation act simultaneously and co-ordinately, restructuring the chromatin and regulating the gene expression during soot apical meristem development and floral differentiation.
Dobkin, David S
Flowering patterns of four Heliconia (Heliconiaceae) species in Trinidad, West Indies were examined for their predictability and availability to the nectarivores that rely on Heliconia floral nectar. Principal flower visitors are trapling hermit hummingbirds; inflorescences are inhabited by nectarivorous hummingbird flower mites that move between inflorescences by riding in the hummingbirds' nares. Heliconia inflorescences flower for 40-200 days, providing long-term sources of copious nectar (30-60 μl per flower), but each Heliconia flower lasts only a single day. As an inflorescence ages the interval increases between open flowers within a bract; wet-season inflorescences produce open flowers more slowly than dry-season conspecifics.Estimated daily energy expenditures for hermit hummingbirds demonstrate that slow production of short-lived open flowers plus low inflorescence density preclude territorial defense of Heliconia by the hermits. Heliconia flowering patterns are viewed as a means of (i) regulating reproductive investment by the plants through staggered flower production over long periods of time, and (ii) maintaining outcrossing by necessitating a traplining visitation pattern by its hummingbird pollinators. I suggest that Heliconia exhibit a two-tiered pollination system by using hermit hummingbirds primarily for outcrossing and using hummingbird flower mites primarily for self-pollination.
Full Text Available The timing of flowering in perennial plants is crucial for their survival in temperate climates and is regulated by the duration of bud dormancy. Bud dormancy release and bud break depend on the perception of cumulative chilling during endodormancy and heat during the bud development. The objectives of this work were to identify candidate genes involved in dormancy and flowering processes in sweet cherry, their mapping in two mapping progenies 'Regina' × 'Garnet' and 'Regina' × 'Lapins', and to select those candidate genes which co-localized with quantitative trait loci (QTLs associated with temperature requirements for bud dormancy release and flowering. Based on available data on flowering processes in various species, a list of 79 candidate genes was established. The peach and sweet cherry orthologs were identified and primers were designed to amplify sweet cherry candidate gene fragments. Based on the amplified sequences of the three parents of the mapping progenies, SNPs segregations in the progenies were identified. Thirty five candidate genes were genetically mapped in at least one of the two progenies and all were in silico mapped. Co-localization between candidate genes and QTLs associated with temperature requirements and flowering date were identified for the first time in sweet cherry. The allelic composition of the candidate genes located in the major QTL for heat requirements and flowering date located on linkage group 4 have a significant effect on these two traits indicating their potential use for breeding programs in sweet cherry to select new varieties adapted to putative future climatic conditions.
Lou, P.; Jianjun Zhao, Jianjun; Kim, J.S.; Shen, Shuxing; Pino del Carpio, D.; Song, Xiaofei; Jin, M.; Vreugdenhil, D.; Wang, Xiaowu; Koornneef, M.; Bonnema, A.B.
Wide variation for morphological traits exists in Brassica rapa and the genetic basis of this morphological variation is largely unknown. Here is a report on quantitative trait loci (QTL) analysis of flowering time, seed and pod traits, growth-related traits, leaf morphology, and turnip formation in
Lou, P.; Jianjun Zhao, Jianjun; Kim, J.S.; Shen, Shuxing; Pino del Carpio, D.; Song, Xiaofei; Jin, M.; Vreugdenhil, D.; Wang, Xiaowu; Koornneef, M.; Bonnema, A.B.
Wide variation for morphological traits exists in Brassica rapa and the genetic basis of this morphological variation is largely unknown. Here is a report on quantitative trait loci (QTL) analysis of flowering time, seed and pod traits, growth-related traits, leaf morphology, and turnip formation in
Dewi Ayu Lestari
Full Text Available Annona is a genus belongs to Annonaceae family, consisting of numerous species that produce edible fruit. Four species namely A. glabra, A. montana, A. muricata and A. squamosa collections of Purwodadi Botanic Garden were recorded for its flowering and fruiting times, since November 2010 to April 2013. The data were scored and complemented with climate data (temperature, rainfall intensity, humidity then analyzed using multiple linear regression analysis. The result showed that humidity was the most affected climate factors on the flowering and fruiting times of those species. Specifically, rainfall intensity (0-550 mm affected to Annona muricata, temperature (25,56-28,33°C and humidity (66,83-85,02% to Annona squamosa, and humidity to A. glabra (71,62-85,02% and A. montana (71,62 to 82,94 % as well. Flowering time of A. glabra occurs three times a year in wet and dry, and fruiting occurs twice a year in the same month. Annona muricata is flowering throughout the year and fruiting twice a year in wet. A. montana and A. squamosa recorded one a year during the wet month.
Function of protein ubiquitination and SUMOylation in regulating flowering time of plants:A Function of protein ubiquitination and SUMOylation in regulating flowering time of plants:A review%蛋白泛素化和类泛素化修饰在植物开花时间调控中的作用
张孝廉; 张吉顺; 邹颉; 赵杰宏; 任学良
Summary Flowering is an important process in the life cycle of plants to complete the transition from vegetative growth to reproductive growth and to ensure the yield and production of next generation . Therefore , flowering time is a considerable agronomic trait in plants . There are many factors influencing flowering time , including internal factors , such as hormone and carbohydrate , and environmental factors , such as light and temperature . Different plant species have evolved complicated networks to modulate the flowering time accurately in response to environmental cues and endogenous signals . Studies in A rabidopsis have led to the identification of the major flowering pathways: the photoperiod pathway , the vernalization pathway , the ambient temperature pathway , the autonomous pathway , the gibberellic acid (GA) pathway and the age pathway . Multiple flowering regulatory pathways converge to control the activation of floral integrator genes , such as FT and SOC1 . The flowering time genes and their regulation pathways are highly conserved in A rabidopsis , rice and other higher plants . The key regulators of floral transition have been studied extensively in plants . As aspects of protein post‐translational modifications , the ubiquitin/26S proteasome pathway and SUMOylation play key roles in almost every aspect of growth and development for plants ,including the regulation of plant flowering time . Protein stability , degradation , location , and interaction with other proteins were also regulated under these pathways . The ubiquitination pathway usually contains three steps . First , the E1 ( ubiquitin activating enzyme) forms a thioester bond with the C terminus of the 76‐amino acid ubiquitin protein . Second , the activated ubiquitin is transferred to an E2 ( ubiquitin conjugating enzyme) . Third , with the help of the E3 ligase , ubiquitin is transferred to the substrate by E2 , and at last forms a ubiquitinated substrate protein . These
Goodrich, Katherine R; Raguso, Robert A
Floral scent is a key component of floral display, and probably one of the first floral attractants linking insect pollinators to the radiation of Angiosperms. In this article, we investigate floral scent in two extra-tropical genera of Annonaceae. We discuss floral scent in the context of differing pollination strategies in these genera, and compare their scent to that of a close tropical relative. Floral volatiles were collected for Annona glabra, Asimina and Deeringothamnus whole flowers and dissected floral organs, using a standardized static-headspace solid phase microextraction method. Scents were analyzed using gas chromatography-mass spectrometry, and identified using known standards. The floral scents of these species are highly dynamic, varying between floral organs, sexual stages and species. Maroon-flowered species of Asimina produce 'yeasty' odors, dominated by fermentation volatiles and occasionally containing sulfurous or nitrogenous compounds. White-flowered species of Asimina and Deeringothamnus produce pleasant odors characterized by lilac compounds, benzenoids and hydrocarbons. Annona glabra produces a strong, fruity-acetonic scent dominated by 3-pentanyl acetate and 1,8-cineole. The fermented/decaying scents of maroon-flowered species of Asimina suggest mimicry-based pollination strategies similar to aroids and stapeliads, whereas the pleasant scents of white-flowered species of Asimina suggest honest, reward-based pollination strategies. The scent of Annona glabra is typical of specialized beetle pollination systems common to tropical Annonaceae.
Heusden, van E.C.H.
The present paper describes the diversity in floral characters of Annonaceae and their distribution over the family, and discusses their value for classification and generic delimitation. Flower morphology predominated historical classifications of this family since Hooker & Thomson (1855)
Guzmán, B; Gómez, J M; Vargas, P
The association between plants and flower visitors has been historically proposed as a main factor driving the evolutionary change of both flower and pollinator phenotypes. The considerable diversity in floral morphology within the tribe Antirrhineae has been traditionally related to pollinator types. We used empirical data on the flower visitors from 59 Antirrhineae taxa from the literature and our own field surveys, which provide an opportunity to test whether flower phenotypes are reliable predictors of visitors and pollinator niches. The degree of adjustment between eight key floral traits and actual visitors was explored by testing the predictive value of inferred pollinator syndromes (i.e. suites of floral traits that characterise groups of plant species related to pollination). Actual visitors and inferred pollinator niches (categorisation of visitors' association using a modularity algorithm) were also explored using Linear Discriminant Analysis (LDA). The bee pollinator niche is correctly classified for flowers with dull corolla colour, without nectar guides, as the most important predictor. Both predictive value and statistical classification prove useful in classifying Antirrhineae taxa and the bee pollinator niche, mostly as a consequence of the high proportion of genera and taxa with occluded corollas primarily visited by bees. Our predictive approach rendered a high Positive Predictive Value (PPV) of floral traits in the diagnosis of visitors/pollinator niches. In particular, a high PPV was found for bees as both visitors and forming pollinator niches. In addition, LDA showed that four pollinator niches are well defined based on floral traits. The large number of species visited by bees irrespective of pollinator syndromes leads us to hypothesise their generalist pollinator role, despite the phenotypically specialised flowers of Antirrhineae. © 2017 German Botanical Society and The Royal Botanical Society of the Netherlands.
Youfa Cheng; Yunde Zhao
Auxin has long been implicated in many aspects of plant growth and development including flower development. However, the exact roles of auxin in flower development have not been well defined until the recent identification of auxin biosynthesis mutants. Auxin is necessary for the initiation of floral primordia,and the disruption of auxin biosynthesis, polar auxin transport or auxin signaling leads to the failure of flower formation. Auxin also plays an essential role in specifying the number and identity of floral organs.Further analysis of the relationship between the auxin pathways and the known flower development genes will provide critical information regarding mechanisms of organogenesis and pattern formation in plants.
Bowman, John L.; Sakai, Hajime; Jack, Thomas; Weigel, Detlef; Mayer, Ulrike; Meyerowitz, Elliot M.
We describe a locus, SUPERMAN, mutations in which result in extra stamens developing at the expense of the central carpels in the Arabidopsis thaliana flower. The development of superman flowers, from initial primordium to mature flower, is described by scanning electron microscopy. The development of doubly and triply mutant strains, constructed with superman alleles and previously identified homeotic mutations that cause alterations in floral organ identity, is also described. Essentially a...
Moyers, Brook T; Owens, Gregory L; Baute, Gregory J; Rieseberg, Loren H
The patterning of floral ultraviolet (UV) pigmentation varies both intra- and interspecifically in sunflowers and many other plant species, impacts pollinator attraction, and can be critical to reproductive success and crop yields. However, the genetic basis for variation in UV patterning is largely unknown. This study examines the genetic architecture for proportional and absolute size of the UV bullseye in Helianthus argophyllus , a close relative of the domesticated sunflower. A camera modified to capture UV light (320-380 nm) was used to phenotype floral UV patterning in an F 2 mapping population, then quantitative trait loci (QTL) were identified using genotyping-by-sequencing and linkage mapping. The ability of these QTL to predict the UV patterning of natural population individuals was also assessed. Proportional UV pigmentation is additively controlled by six moderate effect QTL that are predictive of this phenotype in natural populations. In contrast, UV bullseye size is controlled by a single large effect QTL that also controls flowerhead size and co-localizes with a major flowering time QTL in Helianthus . The co-localization of the UV bullseye size QTL, flowerhead size QTL and a previously known flowering time QTL may indicate a single highly pleiotropic locus or several closely linked loci, which could inhibit UV bullseye size from responding to selection without change in correlated characters. The genetic architecture of proportional UV pigmentation is relatively simple and different from that of UV bullseye size, and so should be able to respond to natural or artificial selection independently.
Hameister, Steffen; Neuffer, Barbara; Bleeker, Walter
Apart from the common floral architecture in Brassicaceae, variation in flower morphology occurs in several genera within the family and is considered to affect speciation processes. We analysed genetic differentiation and flowering time variation of two floral variants of Capsella bursa-pastoris, the Spe variant and the wild-type, which occur sympatrically in a vineyard in southwest Germany. The Spe variant is characterized by an additional whorl of stamens instead of petals and was formerly classified as an independent taxon 'Capsella apetala' Opiz. Amplified fragment length polymorphism and allozyme analysis revealed a substantial genetic differentiation of the two floral variants and a higher genetic variation within the wild-type subpopulation compared with the Spe subpopulation. The low genetic variation in the mutant provided evidence of a recent local origin or recent introduction. Flowering time analysis indicated that, within the analysed population, the Spe variant flowers significantly later than the wild-type (P < 0.001). We conclude that the evolution and persistence of Spe within a wild-type population is facilitated by high selfing rates and been enhanced by a shift in flowering phenology. Hence, our data provide substantial evidence that the Spe phenotype has established itself as an isolated entity within a wild-type population and may thus serve as a model for the analysis of the evolutionary significance of homeotic mutants in wild populations.
Hainsworth, F Reed; Mercier, Theresa; Wolf, Larry L
The influence of simulated inflorescence design on feeding behavior of 3 male Eugenes fulgens (Rivoli's hummingbird) and one female Lampornis clemenciae (Bluethroated hummingbird) was studied in the laboratory using artificial flowers. Five two-dimensional and three three-dimensional arrangements provided constant rewards per artificial flower. Visits to two-dimensional arrangements had more flower visits per feeding bout, proportionally more flower revisits, and shorter time between flowers than visits to three-dimensional arrangements. This suggests inflorescence design may influence pollen movement by hummingbirds.
Cenci, C. A.; Ceschia, M.
It is well known that forecasting the flowering time of wild vegetation is useful for various sectors of human activity, particularly for all agricultural practices. Therefore, continuing previous work by Cenci et al., we will present here three new phenoclimatic models of the flowering time for a set of wild species, based on an original data sample of flowering dates for more than 500 species, observed at Guidonia (42° N in central Italy) by Montelucci in the period 1960-1982. However, on applying the bootstrap technique to each species sample to check its basic statistical parameters, we found only about 200 to have data samples with an approximately Gaussian distribution. Eventually only 57 species (subdivided into eight monthly subsets from February to September) were used to formulate the models satisfactorily. The flowering date (represented by the z variable), is expressed in terms of two variables x and y by a nonlinear equation of the form z=αxβ+γy. The x variable represents either the degree-day sum (in model 1), or the daily-maximum-temperature sum (in model 2), or the daily-global-insolation sum (in model 3), while y for all three models corresponds to the rainy-day sum. Note that all summations involved in the computation of the variables x and y take place over a certain period of time (preceding the flowering phase), which is a parameter to be determined by the fitting procedure. This parameter, together with the threshold temperature (needed to compute the degree-days in model 1), represents the two implicit parameters of the process, thus the total number of parameters (including these last two) becomes respectively, five for model 1, and four for the other two models. The preliminary results of this work were reported at the XVI International Botanical Congress (1-7 August 1999, St. Louis, Missouri USA).
蔄胜军; 王志英; 苏晓华; 刘巍; 王胜东; 杨志岩
Species such as Populus deltoides Bartr. which are difficult to root and have a long period of seed maturation are not amenable to controlled crossing using floral cuttings in water culture. A controlled breeding technique were studies involving accelerating rooting of floral cuttings by warming the flowerpot using a constant water temperature and at the same time keeping flower buds in dormancy by low temperature environment. The floral cuttings were planted in flowerpots with soil and grown in a cool (3℃) room, the pots being soaked in water at 3 different temperatures. After 25 days, the pots with the floral cuttings were moved to the greenhouse for controlled crossing. The floral cuttings of P. deltoides with internal soil temperature of 22℃ were much superior to the others. Not only did it ease maintaining the vigor of floral cuttings, but also result in more and better seeds, which had 25. 5 root hairs, root length of 31. 8 cm and root weight of 16. 9 g on average. The ones with 18℃ treatment had 12 root hairs, 10. 4 cm root length and 2. 7 g root weight on average, and the ones with 14℃ treatment had 2. 2 root hairs, 4. 2 cm root length and 0. 4 g root weight on average. Efforts to improve rooting of P. deltoids by warming the flowerpot proved to be successful in controlled crossing with species of sections Aigeiros and Tacamahaca. All the floral cuttings in soils at 22℃ produced seeds (100% ) , with an average of 1 800 seeds per floral cutting. 60% floral cuttings at 18 X treatment survived, but the flowers fell because the cuttings had so weak root hairs that they were not enough to support blooming, with an average of 1 000 seeds per fruited cutting. Of those at 14℃ treatment, 20% of cuttings produced seeds, with an average of 500 seeds per fruited cutting, and 80% of the floral cuttings were infected by canker. Other female parents such as P. x canadensis showed similar results to P. deltoides, but floral cuttings of section Tacamahaca have
Yan-Xia Mai; Long Wang; Hong-Quan Yang
Floral initiation is a major step in the life cycle of plants, which is influenced by photoperiod, temperature,and phytohormones, such as gibberellins (GAs). It is known that GAs promote floral initiation under short-day light conditions (SDs) by regulating the floral meristem-identity gene LEAFY (LFY) and the flowering-time gene SUPPRESSOR OF OVEREXPRESSlON OF CO 1 (SOC1). We have defined the role of the auxin signaling component INDOLE-3-ACETIC ACID 7 (IAA7)/AUXIN RESISTANT 2 (AXR2) in the regulation of flowering time in Arabidopsis thaliana. We demonstrate that the gain-of-function mutant of IAA7/AXR2, axr2-1, flowers late under SDs. The exogenous application of GAs rescued the late flowering phenotype of axr2-1 plants. The expression of the GA20 oxidase (GA20ox) genes, GA20ox1 and GA20ox2,was reduced in axr2-1 plants, and the levels of both LFY and SOC1 transcripts were reduced in axr2-1 mutants under SDs. Furthermore, the overexpression of SOC1 or LFY in axr2-1 mutants rescued the late flowering phenotype under SDs. Our results suggest that IAA7/AXR2 might act to inhibit the timing of floral transition under SDs, at least in part, by negatively regulating the expressions of the GA20ox1 and GA20ox2 genes.
Guevara, Lorena I; Jáuregui, Damelis J; Stauffer, Fred W
Copernicia and Washingtonia are two genera of the Trachycarpeae for which no subtribal classification has been proposed, mainly because of the lack of resolution in phylogenetic studies. Morphology and anatomy of flowers whithin Coryphoideae have proven useful for taxa delimitation and supporting relationships among their members. A description of the morphological and anatomical structure of flowers of C. tectorum and W. filifera is presented in order to explore reproductive characters that may clarify their classification within the subfamily and to contribute with floral biology studies. Flowers of cultivated specimens of both taxa and developing fruits of C. tectorum were fixed in FAA, dissected for morphological analysis, and parafin-embedded flowers and fruits were serially sectioned for obtaining permanent slides, using conventional techniques and safranin-fast green staining. All procedures were carried out in the Laboratory of Morpho-Anatomy, Agronomy Faculty of the Universidad Central de Venezuela (UCV). Both species have hermaphroditic flowers. C. tectorum flowers have a thick and pubescent perianth, six stamens with filaments forming a tube fused to the corolla, with rounded projections and an acute apex where the anthers are inserted. W. filifera flowers have an irregularly dentate calyx, and a shortly acuminate corolla, six stamens united by their filaments to the corolla which at the same time are briefly fused to the gynoecium. Cells with druse crystals in the staminal tube are reported for C. tectorum. Only one of the carpels of the gynoecium of C. tectorum develops at fruit stage, and a layer of abundant raphide cells forming a crustaceous endocarp in mature fruits, was found. W. filifera presents the perianth mesophyll with few layers of thick walled cells and schlerenchymatic tissue, gynoecium with apically fused carpels in the ventral region of ovary, free at the base and the apex of the style, where the ventral sutures are opened. C. tectorum
高用顺; 汪以; 朱云美; 林顺权
The rose family (Rosaceae),consists of numerous horticultural plants that have significant economic value.The family includes strawberry,raspberry and rose in the Rosoideae subfamily;fruit trees of apple,pear and loquat in the Maloideae subfamily;and peach,plum and apricot in the Prunoideae subfamily.Consisting of herbaceous plants and woody fruits,the rosaceous plants present various modes of flowering,and the different flowering modes directly influence the flowering ornamental period and/or the fruit harvest period,which are both very important in the horticulture industry.Flowering is the vital physiological process for fruiting,and it is the mark for the transitio n from vegetative to reproductive growth,which is also known as floral transition.In Arabidopsis,a genus in the Brassicaceae family,FLOWERINGLOCUS T (FT) is a key florigen,which integrates the signals regulated by the internal and external environmental cues,and it works at the shoot apical meristem (SAM) to activate the downstream signals for floral transition.TERMINAL FLOWER1 (TFL1) is a homologous gene of FT,which is originally reported in Arabidopsis,the function of TFL1 is opposite to FT,as it plays a role in delaying flowering time.TFL1 suppresses the expression of the downstream genes like LEAFY (LFY),flower meristem identity genes APETALA1 (AP1) and CAULIFLOWER (CAL),and thereby consequently inhibits flowering.The till mutant shows determinate inflorescence and early flowering phenotype.FT can bind with another flowering transcription factor FLOWERING LOCUS D (FD) and form a strong activator to promote the expression of downstream genes,however,when FD binds with TFL1,they form to become a powerful suppressor and inhibit flowering.In the process of vegetative growth,TFL1 strongly expresses in the central area of the inflorescence meristem,and suppresses the translation of AP1 and LFY,in order to keep the meristem at an undifferentiated status.In wild strawberry Fragaria vesca,FvTFL1 highly
Gegear, Robert J; Burns, Rebecca; Swoboda-Bhattarai, Katharine A
Pollination syndromes are suites of floral traits presumed to reflect adaptations to attract and utilize a "primary" type of animal pollinator. However, syndrome traits may also function to deter "secondary" flower visitors that reduce plant fitness through their foraging activities. Here we use the hummingbird-pollinated plant species Mimulus cardinalis as a model to investigate the potential deterrent effects of classic bird syndrome traits on bumble bee foragers. To establish that M. cardinalis flowers elicit an avoidance response in bees, we assessed the choice behavior of individual foragers on a mixed experimental array of M. cardinalis and its bee-pollinated sister species M. lewisii. As expected, bees showed a strong preference against M. cardinalis flowers (only 22% of total bee visits were to M. cardinalis), but surprisingly also showed a high degree of individual specialization (95.2% of total plant transitions were between conspecifics). To determine M. cardinalis floral traits that discourage bee visitation, we then assessed foraging responses of individuals to M. cardinalis-like and M. lewisii-like floral models differing in color, orientation, reward, and combinations thereof. Across experiments, M. cardinalis-like trait combinations consistently produced a higher degree of flower avoidance behavior and individual specialization than expected based on bee responses to each trait in isolation. We then conducted a series of flower discrimination experiments to assess the ability of bees to utilize traits and trait combinations associated with each species. Relative to M. lewisii-like alternatives, M. cardinalis-like traits alone had a minimal effect on bee foraging proficiency but together increased the time bees spent searching for rewarding flowers from 1.49 to 2.65 s per visit. Collectively, our results show that M. cardinalis flowers impose foraging costs on bumble bees sufficient to discourage visitation and remarkably, generate such
Moore, Matthew Robert; Jameson, Mary Liz
The scarab beetle tribe Cyclocephalini (Coleoptera: Scarabaeidae: Dynastinae) is the second largest tribe of rhinoceros beetles, with nearly 500 described species. This diverse group is most closely associated with early diverging angiosperm groups (the family Nymphaeaceae, magnoliid clade, and monocots), where they feed, mate, and receive the benefit of thermal rewards from the host plant. Cyclocephaline floral association data have never been synthesized, and a comprehensive review of this ecological interaction was necessary to promote research by updating nomenclature, identifying inconsistencies in the data, and reporting previously unpublished data. Based on the most specific data, at least 97 cyclocephaline beetle species have been reported from the flowers of 58 plant genera representing 17 families and 15 orders. Thirteen new cyclocephaline floral associations are reported herein. Six cyclocephaline and 25 plant synonyms were reported in the literature and on beetle voucher specimen labels, and these were updated to reflect current nomenclature. The valid names of three unavailable plant host names were identified. We review the cyclocephaline floral associations with respect to inferred relationships of angiosperm orders. Ten genera of cyclocephaline beetles have been recorded from flowers of early diverging angiosperm groups. In contrast, only one genus, Cyclocephala, has been recorded from dicot flowers. Cyclocephaline visitation of dicot flowers is limited to the New World, and it is unknown whether this is evolutionary meaningful or the result of sampling bias and incomplete data. The most important areas for future research include: (1) elucidating the factors that attract cyclocephalines to flowers including floral scent chemistry and thermogenesis, (2) determining whether cyclocephaline dicot visitation is truly limited to the New World, and (3) inferring evolutionary relationships within the Cyclocephalini to rigorously test vicarance hypotheses
Gandolfo, M A; Nixon, K C; Crepet, W L
Based on recent molecular systematics studies, the water lily lineage (Nymphaeales) provides an important key to understanding ancestral angiosperm morphology and is of considerable interest in the context of angiosperm origins. Therefore, the fossil record of Nymphaeales potentially provides evidence on both the timing and nature of diversification of one of the earliest clades of flowering plants. Recent fossil evidence of Turonian age (approximately 90 million years B.P.) includes fossil flowers with characters that, upon rigorous analysis, firmly place them within Nymphaeaceae. Unequivocally the oldest floral record of the Nymphaeales, these fossils are closely related to the modern Nymphaealean genera Victoria (the giant Amazon water lily) and Euryale. Although the fossils are much smaller than their modern relatives, the precise and dramatic correspondence between the fossil floral morphology and that of modern Victoria flowers suggests that beetle entrapment pollination was present in the earliest part of the Late Cretaceous.
Ahmed, Sheaza; Ariyaratne, Menaka; Patel, Jigar; Howard, Alexander E; Kalinoski, Andrea; Phuntumart, Vipaporn; Morris, Paul F
Changes in the levels of polyamines are correlated with the activation or repression of developmental response pathways, but the role of polyamine transporters in the regulation of polyamine homeostasis and thus indirectly gene expression, has not been previously addressed. Here we show that the A. thaliana and rice transporters AtPUT5 and OsPUT1 were localized to the ER, while the AtPUT2, AtPUT3, and OsPUT3 were localized to the chloroplast by transient expression in N. benthamiana. A. thaliana plants that were transformed with OsPUT1 under the control the PUT5 promoter were delayed in flowering by 16days. In contrast, put5 mutants flowered four days earlier than WT plants. The delay of flowering was associated with significantly higher levels of spermidine and spermidine conjugates in the leaves prior to flowering. A similar delay in flowering was also noted in transgenic lines with constitutive expression of either OsPUT1 or OsPUT3. All three transgenic lines had larger rosette leaves, thicker flowering stems, and produced more siliques than wild type plants. In contrast, put5 plants had smaller leaves, thinner flowering stems, and produced fewer siliques. Constitutive expression of PUTs was also associated with an extreme delay in both plant senescence and maturation rate of siliques. These experiments provide the first genetic evidence of polyamine transport in the timing of flowering, and indicate the importance of polyamine transporters in the regulation of flowering and senescence pathways.
Carrie A Eberle
Full Text Available Echium (Echium plantagineum L. is an alternative oilseed crop in summer-wet temperate regions that provides floral resources to pollinators. Its seed oil is rich in omega-3 fatty acids, such as stearidonic acid, which is desired highly by the cosmetic industry. Seeds were sown in field plots over three years in western Minnesota in spring (early-sown or early summer (late-sown, and flower abundance, pollinator visitation, and seed yields were studied. Initial flowering commenced 41 to 55 d after sowing, and anthesis duration (first flowering to harvest was 34 to 70 d. Late sowing dates delayed anthesis, but increased the intensity of visitation by pollinators. Cumulative flower densities ranged from 1 to 4.5 billion ha-1. Flowers attracted numerous honey bees (Apis mellifera L., as many as 35 per minute of observation, which represented about 50% of all insect visitors. Early-sown echium produced seed yields up to 750 kg ha-1, which were 2-29 times higher than those of late-sown echium. Early sowing of echium in Minnesota provides abundant floral resources for pollinators for up to two months and simultaneously produces seed yields whose profits rival those of corn (Zea mays L..
MUNIRMuhammad; JAMILMuhammad[; BALOCHJalal-ud-din; KHATTAKKhalidRehman
Shades of different light intensities (29%, 43%, 54%,60% or 68%) along with control (no shade) were studied to observe their effects on the flowering time and plant quality. A hyperbolic relationship was observed between different light intensities under shade,and time to flowering.The total number of flower buds showed a curvilinear relationship with light intensities. Growth parameters related to the plant characteristics such as plant height,leaf area and plant fresh weight were improved under shading treatments at the expense of flowering time and number of flower buds.However,both linear and polynomial models applied assumed that cultivar Chimes White was equally sensitive to light intensity throughout development.
Internicola, Antonina I; Harder, Lawrence D
Most rewardless orchids engage in generalized food-deception, exhibiting floral traits typical of rewarding species and exploiting the instinctive foraging of pollinators. Generalized food-deceptive (GFD) orchids compete poorly with rewarding species for pollinator services, which may be overcome by flowering early in the growing season when relatively more pollinators are naive and fewer competing plant species are flowering, and/or flowering for extended periods to enhance the chance of pollinator visits. We tested these hypotheses by manipulating flowering time and duration in a natural population of Calypso bulbosa and quantifying pollinator visitation based on pollen removal. Both early and long flowering increased bumble-bee visitation compared with late and brief flowering, respectively. To identify the cause of reduced visitation during late flowering, we tested whether negative experience with C. bulbosa (avoidance learning) and positive experience with a rewarding species, Arctostaphylos uva-ursi, (associative learning) by captive bumble-bees could reduce C. bulbosa's competitiveness. Avoidance learning explained the higher visitation of early- compared with late-flowering C. bulbosa. The resulting pollinator-mediated selection for early flowering may commonly affect GFD orchids, explaining their tendency to flower earlier than rewarding orchids. For dissimilar deceptive and rewarding sympatric species, associative learning may additionally favour early flowering by GFD species.
Skøt, Leif; Sanderson, Ruth; Thomas, Ann
The Arabidopsis (Arabidopsis thaliana) FLOWERING LOCUS T (FT) gene and its orthologs in other plant species (e.g. rice [Oryza sativa] OsFTL2/Hd3a) have an established role in the photoperiodic induction of flowering response. The genomic and phenotypic variations associated with the perennial...... ryegrass (Lolium perenne) ortholog of FT, designated LpFT3, was assessed in a diverse collection of nine European germplasm populations, which together constituted an association panel of 864 plants. Sequencing and genotyping of a series of amplicons derived from the nine populations, containing...... or structured association with further correction using genomic control indicated significant associations between LpFT3 and variation in flowering time. These associations were corroborated in a validation population segregating for the same major alleles. The most "diagnostic" region of genomic variation...
Full Text Available Wintersweet (Chimonanthus praecox is familiar as a garden plant and woody ornamental flower. On account of its unique flowering time and strong fragrance, it has a high ornamental and economic value. Despite a long history of human cultivation, our understanding of wintersweet genetics and molecular biology remains scant, reflecting a lack of basic genomic and transcriptomic data. In this study, we assembled three cDNA libraries, from three successive stages in flower development, designated as the flower bud with displayed petal, open flower and senescing flower stages. Using the Illumina RNA-Seq method, we obtained 21,412,928, 26,950,404, 24,912,954 qualified Illumina reads, respectively, for the three successive stages. The pooled reads from all three libraries were then assembled into 106,995 transcripts, 51,793 of which were annotated in the NCBI non-redundant protein database. Of these annotated sequences, 32,649 and 21,893 transcripts were assigned to gene ontology categories and clusters of orthologous groups, respectively. We could map 15,587 transcripts onto 312 pathways using the Kyoto Encyclopedia of Genes and Genomes pathway database. Based on these transcriptomic data, we obtained a large number of candidate genes that were differentially expressed at the open flower and senescing flower stages. An analysis of differentially expressed genes involved in plant hormone signal transduction pathways indicated that although flower opening and senescence may be independent of the ethylene signaling pathway in wintersweet, salicylic acid may be involved in the regulation of flower senescence. We also succeeded in isolating key genes of floral scent biosynthesis and proposed a biosynthetic pathway for monoterpenes and sesquiterpenes in wintersweet flowers, based on the annotated sequences. This comprehensive transcriptomic analysis presents fundamental information on the genes and pathways which are involved in flower development in
Sedonia D Sipes
Full Text Available Floral scent is likely important to the pollination of parasitic plants, despite that it has not been well-studied. We studied the pollination ecology of the North American stem holoparasite Pilostyles thurberi (Apodanthaceae at two field sites in Texas. To identify effective pollinators, we collected floral visitors to P. thurberi flowers, observed their foraging behavior, and looked for P. thurberi pollen on their bodies. Augochloropsis metallica bees (Halictidae and eumenine potter wasps (Vespidae were pollinators. P. thurberi flowers are visually inconspicuous but produce a strong fruity fragrance. GC/MS analysis of whole floral extracts and dynamic headspace samples revealed the fragrance to be an unusually simple bouquet of raspberry ketone and several eugenols. Comparison of scent profiles to those from uninfected host plants (Dalea formosa allowed putative separation of parasite and host volatiles. This is the first report of the constituents of floral fragrance in Apodanthaceae.
Yu, Yanchong; Liu, Zhenhua; Wang, Long; Kim, Sang-Gyu; Seo, Pil J; Qiao, Meng; Wang, Nan; Li, Shuo; Cao, Xiaofeng; Park, Chung-Mo; Xiang, Fengning
Flowering is crucial for achieving reproductive success. A large number of well-delineated factors affecting flowering are involved in complex genetic networks in Arabidopsis thaliana. However, the underlying part played by the WRKY transcription factors in this process is not yet clear. Here, we report that WRKY71 is able to accelerate flowering in Arabidopsis. An activation-tagged mutant WRKY71-1D and a constitutive over-expresser of WRKY71 both flowered earlier than the wild type (WT). In contrast, both the RNA interference-based multiple WRKY knock-out mutant (w71w8 + 28RNAi) and the dominant repression line (W71-SRDX) flowered later. Gene expression analysis showed that the transcript abundance of the flowering time integrator gene FLOWERING LOCUS T (FT) and the floral meristem identity genes LEAFY (LFY), APETALA1 (AP1) and FRUITFULL (FUL) were greater in WRKY71-1D than in the WT, but lower in w71w8 + 28RNAi and W71-SRDX. Further, WRKY71 was shown to bind to the W-boxes in the FT and LFY promoters in vitro and in vivo. The suggestion is that WRKY71 activity hastens flowering via the direct activation of FT and LFY.
Glycine max is a photoperiodic short-day plant and the practical consequence of the response is latitude and sowing period limitations to commercial crops.Genetic and physiological studies using the model plants Arabidopsis thaliana and rice (Oryza sativa)have uncovered several genes and genetic pathways controlling the process,however information about the corresponding pathways in legumes is scarce.Data mining prediction methodologies,Including multiple sequence alignment,phylogenetic analysis,bioinformatics expression and sequence motif pattern identification were used to identify soybean genes involved In day length perception and photoperiodic flowering induction.We have investigated approximately 330 000 sequences from open-access databases and have identified all bona fide central oscillator genes and circadian photoreceptors from A.thaliana in soybean sequence databases.We propose e working model for the photoperiodic control of flowering time in G.max,based on the identified key components.These results demonstrate the power of comparative genomics between model systems and crop species to elucidate the several aspects of plant physiology and metabolism.
Friis, Else Marie; Crane, P.R.; Pedersen, Kaj Raunsgaard
The recent discovery of diverse fossil flowers and floral organs in Cretaceous strata has revealed astonishing details about the structural and systematic diversity of early angiosperms. Exploring the rich fossil record that has accumulated over the last three decades, this is a unique study...... based on research into Early and Late Cretaceous fossil floras from Europe and North America, the authors draw on direct palaeontological evidence of the pattern of angiosperm evolution through time. Synthesising palaeobotanical data with information from living plants, this unique book explores...... the latest research in the field, highlighting connections with phylogenetic systematics, structure and the biology of extant angiosperms....
Olesen, Jørgen E; Børgesen, Christen Duus; Elsgaard, Lars
The phenological development of cereal crops from emergence through flowering to maturity is largely controlled by temperature, but also affected by day length and potential physiological stresses. Responses may vary between species and varieties. Climate change will affect the timing of cereal...... crop development, but exact changes will also depend on changes in varieties as affected by plant breeding and variety choices. This study aimed to assess changes in timing of major phenological stages of cereal crops in Northern and Central Europe under climate change. Records on dates of sowing......, flowering, and maturity of wheat, oats and maize were collected from field experiments conducted during the period 1985–2009. Data for spring wheat and spring oats covered latitudes from 46 to 64°N, winter wheat from 46 to 61°N, and maize from 47 to 58°N. The number of observations (site...
Li-Min CAO; Nian-He XIA
The floral organogenesis and development of Delavaya toxocarpa Franch. (Sapindaceae) were studied under scanning electron microscope and light microscope to determine its systematic position within Sapindaceae. Flowers arise in terminal thyrses. The sepal primordia initiate in a spiral (2/5) sequence, which are not synchronous. The five petal primordia initiate almost synchronously and alternate with sepal primordia. Eight stamens initiate almost simultaneously and their differentiation precedes that of the petals. The last formed petal and one stamen initiate from a common primordium. Mature stamens curve inwards and cover the ovary in bud. The gynoecium begins as a hemispheric primordium on which two carpellary lobes arise simultaneously. Later in development a single gynocium is formed with two locules and two ovules per locule. Floral morphology suggests a closer affinity with Sapindaceae, although certain features of floral ontogenesis are similar to those observed in certain members of the former Hippocastanaceae, such as Handeliodendron.
Athayde, Eduardo Anversa; Morellato, Leonor Patrícia Cerdeira
Fragmentation exposes plants to extreme environmental conditions with implications for species phenology and reproduction.We investigated whether isolation and edge effects influence size, flowering time, fruit set, and seedling establishment of Anadenanthera peregrina var. falcata. We compared trees in the interior (n =85), and on the edge (n =74) of a cerrado savanna fragment as well as in a pasture (n =26) with respect to size, flowering phenology, flower and fruit production, fruit and seed set, predispersal seed predation, and seedling establishment. Trees in the pasture were larger and produced a higher number of flowers and fruits than trees on the edge and interior, yet seed set did not differ across environments. The plant size structure explained the flower and fruit production, and the self-compatibility breeding system caused a similar seed set regardless of the environment. First flowering was later and fruit set higher in the interior. We argue that time of first flower influenced the fruit set of Anadenathera. Edge and isolated trees started to flower earlier as a response to microclimatic conditions--mainly temperature--reducing the fruit set. Predispersal seed predation was lower among pasture trees. Conversely, we found seedlings only on the edge and in the interior of cerrado, suggesting that the pasture was of poor quality habitat for Anadenanthera recruitment. Isolation affected the plant size structure and reproduction of Anadenanthera trees. Studies comparing plant phenology under contrasting environmental conditions may offer clues on how global change may affect plant reproduction in the tropics.
Athayde, Eduardo Anversa; Morellato, Leonor Patrícia Cerdeira
Fragmentation exposes plants to extreme environmental conditions with implications for species phenology and reproduction. We investigated whether isolation and edge effects influence size, flowering time, fruit set, and seedling establishment of Anadenanthera peregrina var. falcata. We compared trees in the interior ( n = 85), and on the edge ( n = 74) of a cerrado savanna fragment as well as in a pasture ( n = 26) with respect to size, flowering phenology, flower and fruit production, fruit and seed set, predispersal seed predation, and seedling establishment. Trees in the pasture were larger and produced a higher number of flowers and fruits than trees on the edge and interior, yet seed set did not differ across environments. The plant size structure explained the flower and fruit production, and the self-compatibility breeding system caused a similar seed set regardless of the environment. First flowering was later and fruit set higher in the interior. We argue that time of first flower influenced the fruit set of Anadenathera. Edge and isolated trees started to flower earlier as a response to microclimatic conditions—mainly temperature—reducing the fruit set. Predispersal seed predation was lower among pasture trees. Conversely, we found seedlings only on the edge and in the interior of cerrado, suggesting that the pasture was of poor quality habitat for Anadenanthera recruitment. Isolation affected the plant size structure and reproduction of Anadenanthera trees. Studies comparing plant phenology under contrasting environmental conditions may offer clues on how global change may affect plant reproduction in the tropics.
Prajakta V Belsare; Balasubramanian Sriram; Milind G Watve
In most insect-pollinated flowers, pollinators cannot detect the presence of nectar without entering the flower. Therefore, flowers may cheat by not producing nectar and may still get pollinated. Earlier studies supported this ‘cheater flower’ hypothesis and suggested that the cost saving by cheater flowers could be the most predominant selective force in the evolution of nectarless flowers. Previous models as well as empirical studies have addressed the problem of optimizing the proportion of nectarless and nectarful flowers. However, there has been no attempt to optimize the investment in nectar production along with that in floral display. One of the key questions that arises is whether the floral display will evolve to be an honest indicator of nectar reward. We use a mathematical model to cooptimize the investments in nectar and floral display in order to achieve maximum reproductive success. The model assumes that pollinators rely on a relative rather than an absolute judgement of reward. A conspicuous floral display attracts naïve pollinators on the one hand and enhances pollinator learning on the other. We show that under these assumptions, plant–pollinator co-evolution leads to honest signalling, i.e. a positive correlation between display and reward.
Okada, Ryo; Nemoto, Yasue; Endo-Higashi, Naokuni; Izawa, Takeshi
For genetically homogeneous crops, the timing of flowering is determined largely by the cultivation environment and is strongly associated with the yield and quality of the harvest(1). Flowering time and other agronomical traits are often tightly correlated, which can lead to difficulty excluding the effects of flowering time when evaluating the characteristics of different genetic varieties(2). Here, we describe the development of transgenic rice plants whose flowering time can be controlled by specific agrochemicals. We first developed non-flowering rice plants by overexpressing a floral repressor gene, Grain number, plant height and heading date 7 (Ghd7)(3,4), to inhibit any environmentally induced spontaneous flowering. We then co-transformed plants with a rice florigen gene, Heading date 3a (Hd3a)(5), which is induced by the application of specific agrochemicals. This permitted the flowering time to be experimentally controlled regardless of the cultivation environment: some transgenic plants flowered only after agrochemical treatment. Furthermore, plant size and yield-related traits could, in some cases, be increased owing to both a longer duration of vegetative growth and an increased panicle size. This ability to control flowering time experimentally, independently of environmental variables, may lead to production of crops suitable for growth in different climates and facilitate breeding for various agronomical traits.
Sara L Martin
Full Text Available Whole genome duplications have occurred recurrently throughout the evolutionary history of eukaryotes. The resulting genetic and phenotypic changes can influence physiological and ecological responses to the environment; however, the impact of genome copy number on evolvability has rarely been examined experimentally. Here, we evaluate the effect of genome duplication on the ability to respond to selection for early flowering time in lines drawn from naturally occurring diploid and autotetraploid populations of the plant Chamerion angustifolium (fireweed. We contrast this with the result of four generations of selection on synthesized neoautotetraploids, whose genic variability is similar to diploids but genome copy number is similar to autotetraploids. In addition, we examine correlated responses to selection in all three groups. Diploid and both extant tetraploid and neoautotetraploid lines responded to selection with significant reductions in time to flowering. Evolvability, measured as realized heritability, was significantly lower in extant tetraploids (^b(T = 0.31 than diploids (^b(T = 0.40. Neotetraploids exhibited the highest evolutionary response (^b(T = 0.55. The rapid shift in flowering time in neotetraploids was associated with an increase in phenotypic variability across generations, but not with change in genome size or phenotypic correlations among traits. Our results suggest that whole genome duplications, without hybridization, may initially alter evolutionary rate, and that the dynamic nature of neoautopolyploids may contribute to the prevalence of polyploidy throughout eukaryotes.
Ivaničová, Zuzana; Jakobson, Irena; Reis, Diana; Šafář, Jan; Milec, Zbyněk; Abrouk, Michael; Doležel, Jaroslav; Järve, Kadri; Valárik, Miroslav
Flowering time variation was identified within a mapping population of doubled haploid lines developed from a cross between the introgressive line 8.1 and spring bread wheat cv. Tähti. The line 8.1 carried introgressions from tetraploid Triticum militinae in the cv. Tähti genetic background on chromosomes 1A, 2A, 4A, 5A, 7A, 1B and 5B. The most significant QTL for the flowering time variation was identified within the introgressed region on chromosome 5A and its largest effect was associated with the VRN-A1 locus, accounting for up to 70% of phenotypic variance. The allele of T. militinae origin was designated as VRN-A1f-like. The effect of the VRN-A1f-like allele was verified in two other mapping populations. QTL analysis identified that in cv. Tähti and cv. Mooni genetic background, VRN-A1f-like allele incurred a delay of 1.9-18.6 days in flowering time, depending on growing conditions. Sequence comparison of the VRN-A1f-like and VRN-A1a alleles from the parental lines of the mapping populations revealed major mutations in the promoter region as well as in the first intron, including insertion of a MITE element and a large deletion. The sequence variation allowed construction of specific diagnostic PCR markers for VRN-A1f-like allele determination. Identification and quantification of the effect of the VRN-A1f-like allele offers a useful tool for wheat breeding and for studying fine-scale regulation of flowering pathways in wheat. Copyright © 2016 Elsevier B.V. All rights reserved.
Modulating days to flowering is a key mechanism in plants for adapting to new environments, and variation in days to flowering drives population structure by limiting mating. To elucidate the genetic architecture of flowering across maize, a quantitative trait, we mapped flowering in five global pop...
Whitney, Heather M; Kolle, Mathias; Alvarez-Fernandez, Ruben; Steiner, Ullrich; Glover, Beverley J
The Hibiscus trionum flower is distinctly patterned, with white petals each with a patch of red pigment at the base, producing a 'bulls-eye' pattern on the whole flower. The red pigmented patches are also iridescent, due to the presence of a series of overlying cuticular striations that act as a diffraction grating. We have previously reported that scanning electron microscopy revealed a sharply defined difference between the surface structure overlying the pigmented patch and that over the rest of the petal, with the diffraction grating only present over the pigmented region. Here we show that differences in petal surface structure overlie differences in pigment color in three other species, in a range of different patterns. Floral patterns have previously been shown to be advantageous in pollinator attraction, and we discuss whether emphasis of pigment patterns by structural color may increase floral recognition by pollinators.
Mao, Tingting; Li, Jinyu; Wen, Zixiang; Wu, Tingting; Wu, Cunxiang; Sun, Shi; Jiang, Bingjun; Hou, Wensheng; Li, Wenbin; Song, Qijian; Wang, Dechun; Han, Tianfu
Soybean (Glycine max (L.) Merr.) is a short day plant. Its flowering and maturity time are controlled by genetic and environmental factors, as well the interaction between the two factors. Previous studies have shown that both genetic and environmental factors, mainly photoperiod and temperature, control flowering time of soybean. Additionally, these studies have reported gene × gene and gene × environment interactions on flowering time. However, the effects of quantitative trait loci (QTL) in response to photoperiod and temperature have not been well evaluated. The objectives of the current study were to identify the effects of loci associated with flowering time under different photo-thermal conditions and to understand the effects of interaction between loci and environment on soybean flowering. Different photoperiod and temperature combinations were obtained by adjusting sowing dates (spring sowing and summer sowing) or day-length (12 h, 16 h). Association mapping was performed on 91 soybean cultivars from different maturity groups (MG000-VIII) using 172 SSR markers and 5107 SNPs from the Illumina SoySNP6K iSelectBeadChip. The effects of the interaction between QTL and environments on flowering time were also analysed using the QTXNetwork. Large-effect loci were detected on Gm 11, Gm 16 and Gm 20 as in previous reports. Most loci associated with flowering time are sensitive to photo-thermal conditions. Number of loci associated with flowering time was more under the long day (LD) than under the short day (SD) condition. The variation of flowering time among the soybean cultivars mostly resulted from the epistasis × environment and additive × environment interactions. Among the three candidate loci, i.e. Gm04_4497001 (near GmCOL3a), Gm16_30766209 (near GmFT2a and GmFT2b) and Gm19_47514601 (E3 or GmPhyA3), the Gm04_4497001 may be the key locus interacting with other loci for controlling soybean flowering time. The effects of loci associated
Full Text Available Floral syndromes are traditionally thought to be associated with particular pollinator groups. Ornithophilous flowers tend to have traits that facilitate bird pollination such as having long, narrow, tubular corollas, often vivid coloration and diluted, sucrose-rich nectar. However, recent studies have shown that flowers attract a broader spectrum of visitors than might be expected. Furthermore, the classification of floral visitors as ‘robbers’ or ‘pollinators’ often is not as simple as it seems, as pollinators can at times act as robbers and vice versa. We studied the species composition, behaviour and ecology of floral visitors, including potential pollinators and robbers, of Heliconia angusta (Heliconiaceae, an endemic understorey herb of the Atlantic Rainforest of Brazil. In addition, the impact of the plant inflorescence attractiveness and of weather and light conditions on visitor abundance and frequency was investigated. Flower visitors were found to be scarce with a total of only 151 visits being observed during 120 h of field observations. A stingless bee species (Trigona sp. appeared to be the most abundant visitor to the ornithophilous flowers of H. angusta, along with four different species of hummingbirds and two species of butterflies. We consider Trigona sp. rather as pollen robber, but which still has the potential to be a secondary pollinator, whereas the hummingbirds were the principle legitimate visitors. Most flower visitors were recorded between 9.00 am and 1.00 pm with a higher number visiting under semi-shaded conditions than in full shade. Hummingbird numbers increased with flower abundance while the other visitor group numbers were not affected.
Full Text Available Las plantas emplean diversas señales visuales y olfativas con la finalidad de atraer a los polinizadores que en su mayoría son insectos. Algunas plantas han desarrollado mecanismos, basándose en mensajes olfativos que los hacen únicos para sus polinizadores específicos. Estos mecanismos, así como las variaciones intra- e interespecíficas en el perfil de los aromas florales han evolucionado para determinadas especies. Los aromas florales son un conjunto de compuestos volátiles orgánicos y para su estudio hay varios métodos que requieren de técnicas que cada vez son más eficientes. El uso de estos aromas podría ser una opción en determinados sistemas de polinización, utilizándolos como atrayente de polinizadores o de depredadores y/o herbívoro para incrementar la producción y disminuir los daños por plagas. En este trabajo se revisan las distintas interacciones de los insectos y los aromas florales, los sistemas específicos planta-polinizador, los métodos de análisis, así como algunos patrones o tendencias de estas interacciones y su aplicación e importancia.Plants use visual and olfactory cues to attract pollinators and to allow them to detect the presence of flowers, which most of them are insects. Some plants have evolved with their pollinators, based on the olfactory messages, which make them unique for their specific pollinators. These mechanisms have evolved in certain plants in relation to their pollinators, and there are also inter and intra-specific variation in fragrance cues which show specific chemical profile for each plant species, so insects attracted are specific to them. Most of the floral scents are organic compounds identified with techniques and methodologies which become more specific and efficient along the time. The application of floral scent could be used as a tool in pollination and pest management. In these studies, insect interaction with floral scent is reviewed and specificity of plant
Ziermann, Janine; Ritz, Markus S; Hameister, Steffen; Abel, Christian; Hoffmann, Matthias H; Neuffer, Barbara; Theissen, Günter
Homeotic changes played a considerable role during the evolution of flowers, but how floral homeotic mutants initially survive in nature has remained enigmatic. To better understand the evolutionary potential of floral homeotic mutants, we established as a model system Stamenoid petals (Spe), a natural variant of Capsella bursa-pastoris (Brassicaceae). In the flowers of Spe plants, petals are transformed into stamens, whereas all other floral organs are unaffected. In contrast with most other homeotic mutants, the Spe variant occurs in relatively stable populations in the wild. In order to determine how the profound change in floral architecture influences plant performance in the wild, we performed common garden experiments running over 3 years. Here, we show that Spe and wild-type plants attract the same assemblage of floral visitors: mainly hoverflies, wild bees and thrips. However, floral visitation is about twice as frequent in wild-type plants as in Spe plants. Nevertheless, the numbers of seeds per fruit were about the same in both variants. Wild-type plants produced more flowers, fruits and seeds per plant than Spe plants, whereas the germination capacity of Spe seeds was higher than that of the wild-type. Determination of volatile composition revealed monoterpenes and 3,4-dimethylbenzaldehyde, which were detected only in wild-type flowers, presumably because they are produced only by petals. Our data indicate that the similar fitness of Spe and wild-type C. bursa-pastoris in the field results from complex compensation between plant architecture and germination capacity. In contrast, flower structure and floral visitation are only of minor importance, possibly because C. bursa-pastoris is mainly self-pollinating.
Determinação do ponto de colheita e indução à abertura floral do crisântemo cultivar White Polaris em diferentes concentrações de sacarose Stage of harvest and flower opening induction at different sucrose concentrations in spray chrysánthemum cv. White Polaris
Victor Julio Flórez Roncancio
Full Text Available Realizou-se pesquisa objetivando determinar o melhor entre quatro pontos de colheita da haste floral de crisântemos de maço do tipo pompom cv. White Polaris a concentração mais adequada de sacarose para tratamento de "pulsing" dessas hastes: estas foram colhidas em estufa de produção comercial, nos pontos preestabelecidos e transportadas para laboratório, onde foram totalmente imersas em água de torneira, à sombra, durante três horas. Selecionaram-se as hastes pela uniformidade do seu desenvolvimento e cortaram-nas sob água na base do caule, entre 50 e 60 cm, e identificadas, o que permitiu avaliar as mudanças morfológicas associadas às inflorescências individuais. As hastes foram distribuídas e mantidas nos diferentes tratamentos de "pulsing" durante 24 horas, à luz branca contínua de 1.500 lux, 60 a 90% de umidade relativa do ar e temperatura ambiente de 25 ± 2°C. Após o tratamento de "pulsing", as hastes foram transferidas para água destilada, permanecendo por 10 horas sob luz branca contínua, nas mesmas condições de laboratório citadas. A vida floral em vaso começou a ser avaliada na instalação do experimento, após o tratamento de "pulsing", e terminou quando as folhas e pétalas perderam a turgescência e o valor decorativo. As hastes colhidas em estádio de botão (25 e 50% de abertura das inflorescências apicais não alcançaram o ponto de abertura adequado em nenhuma das seis concentrações de sacarose (0 a 146,07 mol/m³; as concentrações de 116,9 146,1 mol/m³, porém, estimularam, em geral, a abertura de botões. Os pontos de colheita 1 e 2 (100 e 75% de abertura das inflorescências apicais respectivamente apresentaram bons resultados em todas as concentrações de sacarose.Flowers of spray chrysanthemum cv. White Polaris were cut at 4 stages and treated in pulsing solutions of distilled water plus 0 to 146.1 mol/m³ sucrose. The flowers were harvested in local commercial greenhouses, at various
In the Netherlands the annual fresh flower consumption is 150 items per person, in France it is 80, in the US it is 30, in Japan the money involved amounts to US$11 billion, but in urban China, this is less than I0. Globally when per capita GDP in a country or region goes up to US$6,000, flower consumption will go up too. As per capita GDP in Shanghai isgoing from US$5,000 to US$7,500, the municipal government should include the construction of floral markets as part of its infrastructural development, just as the construction of urban forests, urban parks, urban greenery, and urban environmental investment. The fostering of local floral markets also require joint efforts from the society at large in terms of finance.
Pragadheesh, V S; Chanotiya, Chandan S; Rastogi, Shubhra; Shasany, Ajit K
Jasminum species are among the most preferred fresh cut flowers in India since ancient times. The plant produces small and fragrant flowers, which are of great demand in the preparation of fragrant garlands and also in perfume industries. Floral volatile of Jasminum grandiflorum L. (Family: Oleaceae) was extracted using solid-phase microextraction and analyzed in enantioselective gas chromatography. Chemical classes of identified volatiles revealed the presence of terpenoids, phenylpropanoids, and fatty acid derivatives. Marker constituent of flower volatiles, linalool was selected for analytical characterization on ethyl- and acetyl-β-cyclodextrin stationary phase. (R)-(-)-Linalool was found as major enantiomer in volatiles of floral buds whereas (S)-(+)-linalool predominated in the volatiles of matured flowers. Simultaneously, a quantitative real-time PCR was performed to find the gene expression of linalool synthase to investigate the mechanism of enantiomeric inversion. The emission pattern of (R)-(-)-linalool at different flower developmental stages was well correlated (P = 0.01) with the gene expression of the cloned linalool synthase from J. grandiflorum. We observed that the successive change in (R)- to (S)-linalool ratio from bud to mature flower was mainly due to the enantio- specific transformation and temporal decline of (R)-linalool producing gene in J. grandiflorum. This enantiomeric change also leads to the difference in flower aroma. Furthermore, this is probably the reason behind consumer's acceptance for jasmine buds rather than bloomed flowers in cut flower segments. Copyright © 2017 Elsevier Ltd. All rights reserved.
Anne S Leonard
Full Text Available Floral displays are under selection to both attract pollinators and deter antagonists. Here we show that a common floral trait, a nectar guide pattern, alters the behavior of bees that can act opportunistically as both pollinators and as antagonists. Generally, bees access nectar via the floral limb, transporting pollen through contact with the plant's reproductive structures; however bees sometimes extract nectar from a hole in the side of the flower that they or other floral visitors create. This behavior is called "nectar robbing" because bees may acquire the nectar without transporting pollen. We asked whether the presence of a symmetric floral nectar guide pattern on artificial flowers affected bumble bees' (Bombus impatiens propensity to rob or access nectar "legitimately." We discovered that nectar guides made legitimate visits more efficient for bees than robbing, and increased the relative frequency of legitimate visits, compared to flowers lacking nectar guides. This study is the first to show that beyond speeding nectar discovery, a nectar guide pattern can influence bees' flower handling in a way that could benefit the plant.
Balanzà, Vicente; Martínez-Fernández, Irene; Ferrándiz, Cristina
The role in flowering time of the MADS-box transcription factor fruitfulL (FUL) has been proposed in many works. FUL has been connected to several flowering pathways as a target of the photoperiod, ambient temperature, and age pathways and it is has been shown to promote flowering in a partially redundant manner with suppressor of overexpression of constans 1 (SOC1). However, the position of FUL in these genetic networks, as well as the functional output of FUL activity during floral transition, remains unclear. In this work, a genetic approach has been undertaken to understand better the functional hierarchies involving FUL and other MADS-box factors with well established roles as floral integrators such as SOC1, short vegetative phase (svp) or flowering locus C (FLC). Our results suggest a prominent role of FUL in promoting reproductive transition when photoinductive signalling is suppressed by short-day conditions or by high levels of FLC expression, as in non-vernalized winter ecotypes. A model is proposed where the sequential formation of FUL-SVP and FUL-SOC1 heterodimers may mediate the vegetative and meristem identity transitions, counteracting the repressive effect of FLC and SVP on flowering.
Jie Xu; Tingzhao Rong; Yaxi Liu; Jian Liu; Moju Cao; Jing Wang; Hai Lan; Yunbi Xu; Yanli Lu; Guangtang Pan
The control of flowering is not only important for reproduction,but also plays a key role in the processes of domestication and adaptation.To reveal the genetic architecture for flowering time and photoperiod sensitivity,a comprehensive evaluation of the relevant literature was performed and followed by meta analysis.A total of 25 synthetic consensus quantitative trait loci (QTL) and four hot-spot genomic regions were identified for photoperiod sensitivity including 11 genes related to photoperiod response or flower morphogenesis and development.Besides,a comparative analysis of the QTL for flowering time and photoperiod sensitivity highlighted the regions containing shared and unique QTL for the two traits.Candidate genes associated with maize flowering were identified through integrated analysis of the homologous genes for flowering time in plants and the consensus QTL regions for photoperiod sensitivity in maize (Zea mays L.).Our results suggest that the combination of literature review,meta-analysis and homologous blast is an efficient approach to identify new candidate genes and create a global view of the genetic architecture for maize photoperiodic flowering.Sequences of candidate genes can be used to develop molecular markers for various models of marker-assisted selection,such as marker-assisted recurrent selection and genomic selection that can contribute significantly to crop environmental adaptation.
Li, Wei; Ahn, Il-Pyung; Ning, Yuese; Park, Chan-Ho; Zeng, Lirong; Whitehill, Justin G A; Lu, Haibin; Zhao, Qingzhen; Ding, Bo; Xie, Qi; Zhou, Jian-Min; Dai, Liangying; Wang, Guo-Liang
The components in plant signal transduction pathways are intertwined and affect each other to coordinate plant growth, development, and defenses to stresses. The role of ubiquitination in connecting these pathways, particularly plant innate immunity and flowering, is largely unknown. Here, we report the dual roles for the Arabidopsis (Arabidopsis thaliana) Plant U-box protein13 (PUB13) in defense and flowering time control. In vitro ubiquitination assays indicated that PUB13 is an active E3 ubiquitin ligase and that the intact U-box domain is required for the E3 ligase activity. Disruption of the PUB13 gene by T-DNA insertion results in spontaneous cell death, the accumulation of hydrogen peroxide and salicylic acid (SA), and elevated resistance to biotrophic pathogens but increased susceptibility to necrotrophic pathogens. The cell death, hydrogen peroxide accumulation, and resistance to necrotrophic pathogens in pub13 are enhanced when plants are pretreated with high humidity. Importantly, pub13 also shows early flowering under middle- and long-day conditions, in which the expression of SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 and FLOWERING LOCUS T is induced while FLOWERING LOCUS C expression is suppressed. Finally, we found that two components involved in the SA-mediated signaling pathway, SID2 and PAD4, are required for the defense and flowering-time phenotypes caused by the loss of function of PUB13. Taken together, our data demonstrate that PUB13 acts as an important node connecting SA-dependent defense signaling and flowering time regulation in Arabidopsis.
Rodrigo C.VERGARA; Alejandra TORRES-ARANEDA; Diego A.VILLAGRA; Robert A.RAGUSO; Mary T.K.ARROYO; Cristian A.BILLAGRA
The study of multi-modal communication has only recently been extended to innate and learned interactions between flowers and their animal visitors,and usually only to pollinators.Here we studied the relevance of floral scent and visual display of a night blooming,putatively hawkmoth-poilinated plant Oenothera acaulis(Onagraceae)in the attraction of non-native cockroaches Blatta orientalis(Blattodea:Blattldae),which function as facultative floral lajrcenists in coastal habitats of central Chile.We experimentally decoupled visual(corolla)and olfactory(fragrance)stimuli by presentlng paper corollas and green mesh bags,with or without a freshly-picked natural flower inside.We then contrasted the behavioral responses of roaches in these treatments with those to the natural combination of traits in actual flowers and their respective control treatments,measuring the roaches'frequency of first visits,mean and total residence time spent in each treatment.The roaches primarily used olfactory cues when approaching O.acaulis flowers at two biologically relevant spatial scaies.In addition,the presence of conspecific roaches bad a strong influence on recruitment to the expenrnental arena,increasing the statlstical differences among treatments.Our results suggest a primacy of floral fragrance over visual stimuli in the foraging responses of B.orientalis.Olfactory cues were necessary and sufficient to attract the roaches,and the visual cues presented in our manipulations only marginally increased their attraction within a 20 cm diameter of the stimulus.The full spectrum of floral visitation behavior was not elicited by the artlficial flowers,suggesting the need for addltional tactile or contact chemosensory stimuli not provided by paper.Although the nitrogenous scent compounds that we found in O.acaulis flowers are almost exclusively found in hawkmoth-pollinated flowers,the attractiveness of these compounds to a non-native,facultative flower-visiting insect indicates that they
Delgado Sandoval, Silvia del Carmen; Abraham Juárez, María Jazmín; Simpson, June
Agave tequilana is a monocarpic perennial species that flowers after 5-8 years of vegetative growth signaling the end of the plant's life cycle. When fertilization is unsuccessful, vegetative bulbils are induced on the umbels of the inflorescence near the bracteoles from newly formed meristems. Although the regulation of inflorescence and flower development has been described in detail for monocarpic annuals and polycarpic species, little is known at the molecular level for these processes in monocarpic perennials, and few studies have been carried out on bulbils. Histological samples revealed the early induction of umbel meristems soon after the initiation of the vegetative to inflorescence transition in A. tequilana. To identify candidate genes involved in the regulation of floral induction, a search for MADS-box transcription factor ESTs was conducted using an A. tequilana transcriptome database. Seven different MIKC MADS genes classified into 6 different types were identified based on previously characterized A. thaliana and O. sativa MADS genes and sequences from non-grass monocotyledons. Quantitative real-time PCR analysis of the seven candidate MADS genes in vegetative, inflorescence, bulbil and floral tissues uncovered novel patterns of expression for some of the genes in comparison with orthologous genes characterized in other species. In situ hybridization studies using two different genes showed expression in specific tissues of vegetative meristems and floral buds. Distinct MADS gene regulatory patterns in A. tequilana may be related to the specific reproductive strategies employed by this species.
Senthil Kumar, Rajendran; Shen, Chin-Hui; Wu, Pei-Yin; Suresh Kumar, Subbiah; Hua, Moda Sang; Yeh, Kai-Wun
In Oncidium, redox homeostasis involved in flowering is mainly due to ascorbic acid (AsA). Here, we discovered that Oncidium floral repression is caused by an increase in AsA-mediated NO levels, which is directed by the enzymatic activities of nitrate reductase (NaR) and nitrite reducatase (NiR). Through Solexa transcriptomic analysis of two libraries, ‘pseudobulb with inflorescent bud’ (PIB) and ‘pseudobulb with axillary bud’ (PAB), we identified differentially expressed genes related to NO metabolism. Subsequently, we showed a significant reduction of NaR enzymatic activities and NO levels during bolting and blooming stage, suggesting that NO controlled the phase transition and flowering process. Applying AsA to Oncidium PLB (protocorm-like bodies) significantly elevated the NO content and enzyme activities. Application of sodium nitroprusside (-NO donor) on Arabidopsis vtc1 mutant caused late flowering and expression level of flowering-associated genes (CO, FT and LFY) were reduced, suggesting NO signaling is vital for flowering repression. Conversely, the flowering time of noa1, an Arabidopsis NO-deficient mutant, was not altered after treatment with L-galacturonate, a precursor of AsA, suggesting AsA is required for NO-biosynthesis involved in the NO-mediated flowering-repression pathway. Altogether, Oncidium bolting is tightly regulated by AsA-mediated NO level and downregulation of transcriptional levels of NO metabolism genes. PMID:27731387
Kuppler, Jonas; Höfers, Maren K; Wiesmann, Lisa; Junker, Robert R
The basic units of ecological and evolutionary processes are individuals. Network studies aiming to infer mechanisms from complex systems, however, usually focus on interactions between species, not individuals. Accordingly, the structure and underlying mechanisms of individual-based interaction networks remain largely unknown. In a common garden, we recorded all interactions on flowers and leaves of 97 Sinapis arvensis individuals from seedling stage to fruit set and related interindividual differences in interactions to the plant individuals' phenotypes. The plant individuals significantly differed in their quantitative and qualitative interactions with arthropods on flowers and leaves. These differences remained stable over the entire season and thus were time-invariant. Variation in interacting arthropod communities could be explained by a pronounced intraspecific variability in flowering phenology, morphology and flower scent, and translated into variation in reproductive success. Interestingly, plant individuals with a similar composition of flower visitors were also visited by a similar assemblage of interaction partners at leaves. Our results show that the nonuniformity of plant species has pronounced effects in community ecology, potentially with implications for the persistence of communities and populations, and their ability to withstand environmental fluctuations.
Chanderbali, André S; Albert, Victor A; Leebens-Mack, Jim; Altman, Naomi S; Soltis, Douglas E; Soltis, Pamela S
The debate on the origin and evolution of flowers has recently entered the field of developmental genetics, with focus on the design of the ancestral floral regulatory program. Flowers can differ dramatically among angiosperm lineages, but in general, male and female reproductive organs surrounded by a sterile perianth of sepals and petals constitute the basic floral structure. However, the basal angiosperm lineages exhibit spectacular diversity in the number, arrangement, and structure of floral organs, whereas the evolutionarily derived monocot and eudicot lineages share a far more uniform floral ground plan. Here we show that broadly overlapping transcriptional programs characterize the floral transcriptome of the basal angiosperm Persea americana (avocado), whereas floral gene expression domains are considerably more organ specific in the model eudicot Arabidopsis thaliana. Our findings therefore support the "fading borders" model for organ identity determination in basal angiosperm flowers and extend it from the action of regulatory genes to downstream transcriptional programs. Furthermore, the declining expression of components of the staminal transcriptome in central and peripheral regions of Persea flowers concurs with elements of a previous hypothesis for developmental regulation in a gymnosperm "floral progenitor." Accordingly, in contrast to the canalized organ-specific regulatory apparatus of Arabidopsis, floral development may have been originally regulated by overlapping transcriptional cascades with fading gradients of influence from focal to bordering organs.
Full Text Available Jatropha curcas is a promising feedstock for biofuel production because Jatropha oil is highly suitable for the production of biodiesel and bio-jet fuels. However, Jatropha exhibits a low seed yield as a result of unreliable and poor flowering. APETALA1 (AP1 is a floral meristem and organ identity gene in higher plants. The flower meristem identity genes of Jatropha have not yet been identified or characterized. To better understand the genetic control of flowering in Jatropha, an AP1 homolog (JcAP1 was isolated from Jatropha. An amino acid sequence analysis of JcAP1 revealed a high similarity to the AP1 proteins of other perennial plants. JcAP1 was expressed in inflorescence buds, flower buds, sepals and petals. The highest expression level was observed during the early developmental stage of the flower buds. The overexpression of JcAP1 using the cauliflower mosaic virus (CaMV 35S promoter resulted in extremely early flowering and abnormal flowers in transgenic Arabidopsis plants. Several flowering genes downstream of AP1 were up-regulated in the JcAP1-overexpressing transgenic plant lines. Furthermore, JcAP1 overexpression rescued the phenotype caused by the Arabidopsis AP1 loss-of-function mutant ap1-11. Therefore, JcAP1 is an ortholog of AtAP1, which plays a similar role in the regulation of flowering in Arabidopsis. However, the overexpression of JcAP1 in Jatropha using the same promoter resulted in little variation in the flowering time and floral organs, indicating that JcAP1 may be insufficient to regulate flowering by itself in Jatropha. This study helps to elucidate the function of JcAP1 and contributes to the understanding of the molecular mechanisms of flower development in Jatropha.
Wang, Yizhong; Gu, Xiaofeng; Yuan, Wenya; Schmitz, Robert J; He, Yuehui
Polycomb group (PcG) complexes such as PRC1 mediate transcriptional repression. Here, we show that the plant-specific EMBRYONIC FLOWER1 (EMF1), LIKE HETEROCHROMATIN PROTEIN1, and a histone H3 lysine-4 demethylase form a distinct PcG complex, termed EMF1c, that plays PRC1-like roles and is crucial for regulation of the florigen gene FLOWERING LOCUS T (FT) in Arabidopsis. Long-day photoperiods promote FT expression activation in leaf veins specifically at dusk through the photoperiod pathway to induce Arabidopsis flowering. We found that before dusk and at night, a vascular EMF1c directly represses FT expression to prevent photoperiod-independent flowering, whereas at dusk EMF1 binding to FT chromatin is disrupted by the photoperiod pathway, leading to proper FT activation. Furthermore, a MADS-domain transcription factor and potent floral repressor binds EMF1 to repress FT expression. Our study reveals that the vascular EMF1c integrates inputs from several flowering-regulatory pathways to synchronize flowering time to environmental cues.
Essências florais: intervenção vibracional de possibilidades diagnósticas e terapêuticas Esencias florales: intervención vibracional de posibilidades diagnósticas y terapéuticas Flower essences: vibrational intervention of diagnostic and therapeutic possibilities
Olympia Maria Piedade Gimenes
Full Text Available Este estudo objetivou conhecer à luz da Teoria do Imaginário de Gilbert Durand, por meio do teste AT.9 e sessões de atendimento com essências florais, a eventual ação diagnóstica e terapêutica das mesmas. Realizado com 30 sujeitos, que se tratavam com as essências florais, num consultório particular na cidade de São Paulo. Os instrumentos de análise foram 60 protocolos de AT.9 preenchidos pelos 30 indivíduos em dois momentos e 60 formulações de essências florais. Analisaram-se os traços comuns, afinados e dissonantes, das relações estabelecidas entre o AT.9 e as formulações florais, trazendo evidências da sua capacidade diagnóstica e da sua ação terapêutica, com redução de oito indivíduos desestruturados para somente um. As duas essências que traduziram o tom característico dessa população foram Califórnia Wild Rose e Evening Primrose.Este estudo tuvo como objetivo conocer a la luz de la Teoría del Imaginario de Gilbert Durand, através del test AT.9, y sesiones de atención con esencias florales, la eventual acción diagnóstica y terapéutica de las mismas. Fue realizado con 30 sujetos, que se trataban con las esencias florales, en un consultorio particular en la ciudad de São Paulo. Los instrumentos de análisis fueron 60 protocolos de AT.9 llenados por los 30 individuos en dos momentos y 60 formulaciones de esencias florales. Se analizó los trazos comunes, afinados y disonantes, de las relaciones establecidas entre el AT.9 y las formulaciones florales, trayendo evidencias de la capacidad diagnóstica y de la acción terapéutica de las mismas, con reducción de 8 individuos desestructurados a sólo uno. Las dos esencias que tradujeron el tono característico de esa población fueron California Wild Rose y Evening Primrose.The purpose of this study was to know the probable diagnosis and therapeutic action of the flower essences under the light of the Theory of the Imaginary by Gilbert Durand, through the
Wilkinson, M. D.; Haughn, G. W.
A novel gene that is involved in regulating flower initiation and development has been identified in Arabidopsis. This gene has been designated UNUSUAL FLORAL ORGANS (UFO), with five corresponding nuclear recessive alleles designated ufo[middot]1 to ufo[middot]5. Under short day-length conditions, ufo homozygotes generate more coflorescences than do the wild type, and coflorescences often appear apical to the first floral shoot, resulting in a period of inflorescence development in which regions of floral and coflorescence shoots are produced alternately. ufo enhances the phenotype of weak leafy alleles, and the double mutant Ufo-1 Apetala1-1 produces only coflorescence-like shoots, suggesting that these two genes control different aspects of floral initiation. Floral development was also altered in Ufo plants. Ufo flowers have an altered organ number in all whorls, and organs in the first, second, and third whorls exhibit variable homeotic transformations. Ufo single and double mutant phenotypes suggest that the floral changes result from reduction in class B floral homeotic gene expression and fluctuations in the expression boundaries of class C function and FLO10. Surprisingly, in situ hybridization analysis revealed no obvious differences in expression pattern or level in developing Ufo flowers compared with that of the wild type for any class B or C gene studied. We propose that UFO acts in concert with known floral initiation genes and regulates the domains of floral homeotic gene function.
Díaz Riquelme, José
The general objective of this work is to analyze the regulatory processes underlying flowering transition and inflorescence and flower development in grapevine. Most of these crucial developmental events take place within buds growing during two seasons in two consecutive years. During the first season, the shoot apical meristem within the bud differentiates all the basic elements of the shoot including flowering transition in lateral primordia and development of inflorescence primordia. Thes...
Celikel, F.G.; Doorn, van W.G.
The floral buds of Iris flowers (Iris x hollandica) are enclosed by two sheath leaves. Flower opening depends on lifting the flower up to a position whereby the tepals can move laterally. This upward movement is carried out by elongation of the subtending pedicel and ovary. In the pedicels and ovari
Full Text Available Flowering, the transition from the vegetative to the generative phase, is a decisive time point in the lifecycle of a plant. Flowering is controlled by a complex network of transcription factors, photoreceptors, enzymes and miRNAs. In recent years, several studies gave rise to the hypothesis that this network is also strongly involved in the regulation of other important lifecycle processes ranging from germination and seed development through to fundamental developmental and yield-related traits. In the allopolyploid crop species Brassica napus, (genome AACC, homoeologous copies of flowering time regulatory genes are implicated in major phenological variation within the species, however the extent and control of intraspecific and intergenomic variation among flowering-time regulators is still unclear. To investigate differences among B. napus morphotypes in relation to flowering-time gene variation, we performed targeted deep sequencing of 29 regulatory flowering-time genes in four genetically and phenologically diverse B. napus accessions. The genotype panel included a winter-type oilseed rape, a winter fodder rape, a spring-type oilseed rape (all B. napus ssp. napus and a swede (B. napus ssp. napobrassica, which show extreme differences in winter-hardiness, vernalization requirement and flowering behaviour. A broad range of genetic variation was detected in the targeted genes for the different morphotypes, including non-synonymous SNPs, copy number variation and presence-absence variation. The results suggest that this broad variation in vernalisation, clock and signaling genes could be a key driver of morphological differentiation for flowering-related traits in this recent allopolyploid crop species.
Li, Wei; Dai, Liangying; Wang, Guo-Liang
The ubiquitination pathway is involved in a variety of cellular processes in plant growth, development, and immune responses. However, the function of this pathway in connecting plant development and innate immunity is still largely unknown. Recently, we characterized the U-box/ARM E3 ubiquitin ligase PUB13, which regulates both immune responses and flowering time in Arabidopsis. Here, we show that the rice Spl11 gene can complement the cell death and flowering functions of PUB13 in the pub13 mutant. In addition, HFR1, which functions mainly in photomorphogenesis, was identified as one of the PUB13-interacting proteins through yeast two-hybrid screening and pull-down assays. Because the flowering phenotype of pub13 depends on photoperiod, we propose that PUB13 may regulate HFR1 to fine-tune photomorphogenesis and flowering time in Arabidopsis.
King, Rod W; Evans, Lloyd T
Comprehensive studies in grasses show that gibberellins (GAs) play a role as a florigen. For Lolium temulentum, which flowers in response to a single long day (LD), GAs are a transmitted signal, their content increasing in the leaf early in the LD and then, hours later, at the shoot apex. There is a continuous trail of evidence of hormonal action of these GAs for L. temulentum and support for a similar role in the flowering of other LD-responsive temperate grasses and cereals. A characteristic of the initial flowering responses of grasses and cereals is their limited stem elongation. Interestingly, it is GAs with low effectiveness for stem elongation, GA5 and GA6, that reach the shoot apex and, structurally, are probably not degraded by 2-oxidase enzymes. By contrast, GA1 and GA4 cause stem elongation, may be inactive for floral evocation, and do not reach the vegetative shoot apex apparently because of susceptibility to degradation. However, GA4 can be florally active if protected against 2-oxidases either structurally or by using a 2-oxidase inhibitor. Later in inflorescence development, GA1 and GA4 can be detected at the shoot apex and are florally active if applied. The 2-oxidase restricting accessibility to the apex has probably declined at this time so there is a second florigenic, LD-regulated GA action. A growing body of molecular evidence supporting these actions of GA may provide a future basis for manipulating flowering of grasses and cereals.
Full Text Available Post-transcriptional control is nowadays considered a main checking point for correct gene regulation during development, and RNA binding proteins actively participate in this process. Arabidopsis thaliana FLOWERING LOCUS WITH KH DOMAINS (FLK and PEPPER (PEP genes encode RNA-binding proteins that contain three K-homology (KH-domain, the typical configuration of Poly(C-binding ribonucleoproteins (PCBPs. We previously demonstrated that FLK and PEP interact to regulate FLOWERING LOCUS C (FLC, a central repressor of flowering time. Now we show that FLK and PEP also play an important role in the maintenance of the C-function during floral organ identity by post-transcriptionally regulating the MADS-box floral homeotic gene AGAMOUS (AG. Previous studies have indicated that the KH-domain containing protein HEN4, in concert with the CCCH-type RNA binding protein HUA1 and the RPR-type protein HUA2, facilitates maturation of the AG pre-mRNA. In this report we show that FLK and PEP genetically interact with HEN4, HUA1, and HUA2, and that the FLK and PEP proteins physically associate with HUA1 and HEN4. Taken together, these data suggest that HUA1, HEN4, PEP and FLK are components of the same post-transcriptional regulatory module that ensures normal processing of the AG pre-mRNA. Our data better delineates the roles of PEP in plant development and, for the first time, links FLK to a morphogenetic process.
Yang Jianchang; Liu Lijun; Wang Zhiqin; Lang Youzhong; Zhu Qingsen
The flowering duration of spikelets within a panicle of the rice cultivars of Wuyujing 3 (Japonica), Yangdao 4 (Indica), Shanyou 63 (Indica hybrid rice) and PC311/Zaoxiandang 18 (Indica/japonica hybrid rice) was 5d, 7d, 7d and 8d, respectively. The spikelets flowered on the 2nd day produced the highest endosperm weight (EW) and the most endosperm cells (ECs), and followed by the spikelets flowered on the 1st day. ECs decreased with the delay of flowering of the spikelets flowered from the 3rd day. Within a variety or a hybrid combination, the difference in endosperm cell weight (ECW) was not significant among the grains flowered on different dates. EW and grain-filled percentage (G-FP) were very significantly correlated with ECs, but not with ECW. The earlier the spikelets flowered (except those flowered on the 1st day), the greater the initial proliferation power (R°), the higher the maximum proliferation rate (Vmax) and the higher the mean proliferation rate (V) of ECs, and the shorter the time reaching Vmax, and vice versa. R°, Vmax,V and ECs were significantly correlated with the physiological activities (ATPase activity and the content of spermidine and spermine) of the grains at early grain filling stage. The physiological activities of the grains, R°,Vmax,V, ECs and EW significantly increased after removing 1/2 plants at booting stage and spraying 6-BA 〔N6(benzyl) adenine〕 at early heading stage, and the results were reversed after cutting 1/2 leaves at booting stage. These results suggest that the difference in ECs results in the difference in the grain weight, while the low physiological activities of late-flowered grains are the important reasons for their poor endosperm development.
Gormsen, A. K.; Hense, A.; Toldam-Andersen, T. B.; Braun, P.
Large-scale climate variability largely affects average climatic conditions and therefore is likely to influence the phenology of plants. In NW-Europe, the North Atlantic Oscillation (NAO) particularly influences winter climate and, through climate interactions on plants, flowering time of all tree species. In Denmark, like in many other NW-European countries, flowering of most tree species has become earlier since the end of the 1980’s. To quantify a possible relation between NAO and flowering time of tree species, two sources of phenological information from the Copenhagen area (Denmark) were analysed, i.e. pollen counts of the genus Betula and observed first bloom dates of Prunus avium. The Winter NAO explained 29 and 37% of the variation of monthly mean temperature for February and March, respectively. The influence of temperature on flowering time was up to 56% to 60% for the February April mean. A direct correlation of Winter NAO-index and flowering time also revealed a clear relation but the time of influence was earlier (December to February). This was shown to be the likely result of a combination of direct and time-lagged effects of the NAO on air and sea surface temperature. The NAO signal is apparently stored in the North Sea and then influences temperature east up to the Baltic States. It is shown that Denmark is right in the centre of direct and time-lagged effects of the NAO. This offers the possibility of using the NAO-index for predicting flowering time of Prunus avium. The beginning of pollen flow appears to be influenced too much by short-term perturbations of the climate system decreasing the value of the NAO-index for prediction. However, it indicates a close relationship between natural climate variability, measured by the NAO index, and flowering time of tree species for Denmark.
Maglianesi, María A; Böhning‐Gaese, Katrin; Schleuning, Matthias; Ings, Thomas
... pollinator communities. In this study, we tested whether morphological floral traits were associated with foraging preferences of hummingbirds for artificial and natural flower types in Costa Rica...
Kharouba, Heather M; Vellend, Mark
1. Variation among species in their phenological responses to temperature change suggests that shifts in the relative timing of key life cycle events between interacting species are likely to occur under climate warming. However, it remains difficult to predict the prevalence and magnitude of these shifts given that there have been few comparisons of phenological sensitivities to temperature across interacting species. 2. Here, we used a broad-scale approach utilizing collection records to compare the temperature sensitivity of the timing of adult flight in butterflies vs. flowering of their potential nectar food plants (days per °C) across space and time in British Columbia, Canada. 3. On average, the phenology of both butterflies and plants advanced in response to warmer temperatures. However, the two taxa were differentially sensitive to temperature across space vs. across time, indicating the additional importance of nontemperature cues and/or local adaptation for many species. 4. Across butterfly-plant associations, flowering time was significantly more sensitive to temperature than the timing of butterfly flight and these sensitivities were not correlated. 5. Our results indicate that warming-driven shifts in the relative timing of life cycle events between butterflies and plants are likely to be prevalent, but that predicting the magnitude and direction of such changes in particular cases is going to require detailed, fine-scale data.
Hong YAO; yi-Bo LUO
Pollination limitation is common in flowering plants and is thought to be a factor driving the evolution of floral traits.The plasticity of floral longevity to pollination may be an adaptation of plants to pollen limitation.However,this adaptation is less critical in short-lived flowers.To evaluate pollen limitation and the plasticity of floral longevity to pollination in Potentilla tanacetifolia,a gynodioecious herb with short-lived flowers,we analyzed its breeding system,tested sex-differential pollen limitation,and compared variations in floral display size in natural populations in Duolun County,Inner Mongolia,China.Hand pollination experiments and pollinator exclusion treatments revealed that P tanacetifolia is self-compatible and non-autonomously apomictic and shows sex-differential pollen limitation.The plasticity of floral longevity to pollination was observed; the floral duration of female plants was prolonged by approximately 3-4 hours with pollination exclusion treatment.Moreover,the percentage of flowers displayed on female plants during pollination exclusion treatment was significantly higher than that during natural pollination.Under natural pollination conditions,the percentage of flowers displayed on female plants was significantly higher than on hermaphrodite plants.Furthermore,approximately 50％ of the pollen grains spread out of the anthers of hermaphrodite flowers within 2 h of anthesis; the number of pollen grains adhering to the stigmas of hermaphrodite flowers was significantly higher than that adhering to female flowers when flowers shed their petals.These results indicate that variation in floral longevity may be an adaptive strategy to pollination conditions for gynodioecious P tanacetifolia.
Wang, Ruohan; Zhang, Zhixiang
Floral thermogenesis plays a crucial role in pollination biology, especially in plant-pollinator interactions. We have recently explored how thermogenesis is related to pollinator activity and odour release in Magnolia sprengeri. By analyzing flower temperatures, emission of volatiles, and insect visitation, we found that floral blends released during pistillate and staminate stages were similar and coincided with sap beetle visitation. Thus, odour mimicry of staminate-stage flowers may occur during the pistillate stage and may be an adaptive strategy of Magnolia species to attract pollinators during both stages, ensuring successful pollination. In addition to the biological significance of floral thermogenesis in Magnolia species, we explored the underlying regulatory mechanisms via profiling miRNA expression in M. denudata flowers during thermogenic and non-thermogenic stages. We identified 17 miRNAs that may play regulatory roles in floral thermogenesis. Functional annotation of their target genes indicated that these miRNAs regulate floral thermogenesis by influencing cellular respiration and light reactions. These findings increase our understanding of plant-pollinator interactions and the regulatory mechanisms in thermogenic plants.
Breno M. Freitas
Full Text Available Honey bees depend on flower resources (nectar and pollen to supply individual and colony needs. Although behavioural studies already assessed optimum foraging patterns of bumblebees, honey bees foraging behavioural patterns have been poorly assessed. We used Sysirinchium palmifolium L. (Iridaceae, a low-growing, abundant and anthophilous grassland flower to test the hypotheses that Apis mellifera workers would i spend more time, ii visit a greater number of flowers, and iii travel greater distances within patches of S. palmifolium which were newly opened or not been visited by other pollinators when compared to foraging on patches that were available to pollinators during its whole blooming period (only one day. In two different sunny days, we measured bee activities in an area opened for visitation during the whole anthesis (OP plot treatment and another opened for visitation only half of anthesis (CL plot treatment. We observed bees spending more time, visiting more flowers and travelling more in S. palmifolium CL treatment than the OP plot treatment. Previous studies already showed bees alter their foraging behaviour in the lack of resources. Honey bees are able to remember the period of the day when resources are usually the higher, they probably detect the most promising period to gather resources on S. palmifolium flowers. Since A. mellifera is a pollinator with a wide-distribution and is considered an important cause of changes on native pollinator communities, we support additional studies evaluating its foraging behaviours to better understand how it explores flower resources.
Full Text Available Numerous CCT domain genes are known to control flowering in plants. They belong to the CONSTANS-like (COL and PREUDORESPONSE REGULATOR (PRR gene families, which in addition to a CCT domain possess B-box or response-regulator domains, respectively. Ghd7 is the most recently identified COL gene to have a proven role in the control of flowering time in the Poaceae. However, as it lacks B-box domains, its inclusion within the COL gene family, technically, is incorrect. Here, we show Ghd7 belongs to a larger family of previously uncharacterized Poaceae genes which possess just a single CCT domain, termed here CCT MOTIF FAMILY (CMF genes. We molecularly describe the CMF (and related COL and PRR gene families in four sequenced Poaceae species, as well as in the draft genome assembly of barley (Hordeum vulgare. Genetic mapping of the ten barley CMF genes identified, as well as twelve previously unmapped HvCOL and HvPRR genes, finds the majority map to colinear positions relative to their Poaceae orthologues. Combined inter-/intra-species comparative and phylogenetic analysis of CMF, COL and PRR gene families indicates they evolved prior to the monocot/dicot divergence ∼200 mya, with Poaceae CMF evolution described as the interplay between whole genome duplication in the ancestral cereal, and subsequent clade-specific mutation, deletion and duplication events. Given the proven role of CMF genes in the modulation of cereals flowering, the molecular, phylogenetic and comparative analysis of the Poaceae CMF, COL and PRR gene families presented here provides the foundation from which functional investigation can be undertaken.
Cockram, James; Thiel, Thomas; Steuernagel, Burkhard; Stein, Nils; Taudien, Stefan; Bailey, Paul C; O'Sullivan, Donal M
Numerous CCT domain genes are known to control flowering in plants. They belong to the CONSTANS-like (COL) and PREUDORESPONSE REGULATOR (PRR) gene families, which in addition to a CCT domain possess B-box or response-regulator domains, respectively. Ghd7 is the most recently identified COL gene to have a proven role in the control of flowering time in the Poaceae. However, as it lacks B-box domains, its inclusion within the COL gene family, technically, is incorrect. Here, we show Ghd7 belongs to a larger family of previously uncharacterized Poaceae genes which possess just a single CCT domain, termed here CCT MOTIF FAMILY (CMF) genes. We molecularly describe the CMF (and related COL and PRR) gene families in four sequenced Poaceae species, as well as in the draft genome assembly of barley (Hordeum vulgare). Genetic mapping of the ten barley CMF genes identified, as well as twelve previously unmapped HvCOL and HvPRR genes, finds the majority map to colinear positions relative to their Poaceae orthologues. Combined inter-/intra-species comparative and phylogenetic analysis of CMF, COL and PRR gene families indicates they evolved prior to the monocot/dicot divergence ∼200 mya, with Poaceae CMF evolution described as the interplay between whole genome duplication in the ancestral cereal, and subsequent clade-specific mutation, deletion and duplication events. Given the proven role of CMF genes in the modulation of cereals flowering, the molecular, phylogenetic and comparative analysis of the Poaceae CMF, COL and PRR gene families presented here provides the foundation from which functional investigation can be undertaken.
Sasaki, Eriko; Zhang, Pei; Atwell, Susanna; Meng, Dazhe; Nordborg, Magnus
Understanding how genetic variation interacts with the environment is essential for understanding adaptation. In particular, the life cycle of plants is tightly coordinated with local environmental signals through complex interactions with the genetic variation (G x E). The mechanistic basis for G x E is almost completely unknown. We collected flowering time data for 173 natural inbred lines of Arabidopsis thaliana from Sweden under two growth temperatures (10°C and 16°C), and observed massive G x E variation. To identify the genetic polymorphisms underlying this variation, we conducted genome-wide scans using both SNPs and local variance components. The SNP-based scan identified several variants that had common effects in both environments, but found no trace of G x E effects, whereas the scan using local variance components found both. Furthermore, the G x E effects appears to be concentrated in a small fraction of the genome (0.5%). Our conclusion is that G x E effects in this study are mostly due to large numbers of allele or haplotypes at a small number of loci, many of which correspond to previously identified flowering time genes.
Cadic, Elena; Coque, Marie; Vear, Felicity; Grezes-Besset, Bruno; Pauquet, Jerôme; Piquemal, Joël; Lippi, Yannick; Blanchard, Philippe; Romestant, Michel; Pouilly, Nicolas; Rengel, David; Gouzy, Jerôme; Langlade, Nicolas; Mangin, Brigitte; Vincourt, Patrick
Association mapping and linkage mapping were used to identify quantitative trait loci (QTL) and/or causative mutations involved in the control of flowering time in cultivated sunflower Helianthus annuus. A panel of 384 inbred lines was phenotyped through testcrosses with two tester inbred lines across 15 location × year combinations. A recombinant inbred line (RIL) population comprising 273 lines was phenotyped both per se and through testcrosses with one or two testers in 16 location × year combinations. In the association mapping approach, kinship estimation using 5,923 single nucleotide polymorphisms was found to be the best covariate to correct for effects of panel structure. Linkage disequilibrium decay ranged from 0.08 to 0.26 cM for a threshold of 0.20, after correcting for structure effects, depending on the linkage group (LG) and the ancestry of inbred lines. A possible hitchhiking effect is hypothesized for LG10 and LG08. A total of 11 regions across 10 LGs were found to be associated with flowering time, and QTLs were mapped on 11 LGs in the RIL population. Whereas eight regions were demonstrated to be common between the two approaches, the linkage disequilibrium approach did not detect a documented QTL that was confirmed using the linkage mapping approach.
Bowman, J L; Sakai, H; Jack, T; Weigel, D; Mayer, U; Meyerowitz, E M
We describe a locus, SUPERMAN, mutations in which result in extra stamens developing at the expense of the central carpels in the Arabidopsis thaliana flower. The development of superman flowers, from initial primordium to mature flower, is described by scanning electron microscopy. The development of doubly and triply mutant strains, constructed with superman alleles and previously identified homeotic mutations that cause alterations in floral organ identity, is also described. Essentially additive phenotypes are observed in superman agamous and superman apetala2 double mutants. The epistatic relationships observed between either apetala3 or pistillata and superman alleles suggest that the SUPERMAN gene product could be a regulator of these floral homeotic genes. To test this, the expression patterns of AGAMOUS and APETALA3 were examined in superman flowers. In wild-type flowers, APETALA3 expression is restricted to the second and third whorls where it is required for the specification of petals and stamens. In contrast, in superman flowers, APETALA3 expression expands to include most of the cells that would normally constitute the fourth whorl. This ectopic APETALA3 expression is proposed to be one of the causes of the development of the extra stamens in superman flowers. The spatial pattern of AGAMOUS expression remains unaltered in superman flowers as compared to wild-type flowers. Taken together these data indicate that one of the functions of the wild-type SUPERMAN gene product is to negatively regulate APETALA3 in the fourth whorl of the flower. In addition, superman mutants exhibit a loss of determinacy of the floral meristem, an effect that appears to be mediated by the APETALA3 and PISTILLATA gene products.
Sapir, Yuval; Shmida, Avi; Ne'eman, Gidi
Relationships between flowering plants and their pollinators are usually affected by the amount of reward, mainly pollen or nectar, offered to pollinators by flowers, with these amounts usually positively correlated with floral display. The large Oncocyclus iris flowers, despite being the largest flowers in the East Mediterranean flora, are nectarless and have hidden pollen. No pollinators visit the flowers during daytime, and these flowers are pollinated only by night-sheltering solitary male bees. These iris flowers are partially or fully dark-colored, suggesting that they gather heat by absorbing solar radiation. Here we test the hypothesis that the dark-colored flowers of the Oncocyclus irises offer heat reward to their male solitary bee pollinators. Floral temperature was higher by 2.5 degrees C than ambient air after sunrise. Solitary male bees emerged earlier after sheltering in Oncocyclus flowers than from other experimental shelter types. Pollination tunnels facing east towards the rising sun hosted more male bees than other aspects. We suggest that floral heat reward can explain the evolution of dark floral colors in Oncocyclus irises, mediated by the pollinators' behavior.
Fisher, Kaleigh; Gonthier, David J; Ennis, Katherine K; Perfecto, Ivette
Patterns of bee abundance and diversity across different spatial scales have received thorough research consideration. However, the impact of short- and long-term temporal resource availability on biodiversity has been less explored. This is highly relevant in tropical agricultural systems for pollinators, as many foraging periods of pollinators extend beyond flowering of any single crop species. In this study, we sought to understand how bee communities in tropical agroecosystems changed between seasons, and if short- and long-term floral resource availability influenced their diversity and abundance. We used a threshold analysis approach in order to explore this relationship at two time scales. This study took place in a region dominated by coffee agroecosystems in Southern Mexico. This was an ideal system because the landscape offers a range of coffee management regimes that maintain heterogeneity in floral resource availability spatially and temporally. We found that the bee community varies significantly between seasons. There were higher abundances of native social, solitary and managed honey bees during the dry season when coffee flowers. Additionally, we found that floral resources from groundcover, but not trees, were associated with bee abundance. Further, the temporal scale of the availability of these resources is important, whereby short-term floral resource availability appears particularly important in maintaining high bee abundance at sites with lower seasonal complementarity. We argue that in addition to spatial resource heterogeneity, temporal resource heterogeneity is critical in explaining bee community patterns, and should thus be considered to promote pollinator conservation. © 2017 by the Ecological Society of America.
Mark A Genung
Full Text Available BACKGROUND: In the emerging field of community and ecosystem genetics, genetic variation and diversity in dominant plant species have been shown to play fundamental roles in maintaining biodiversity and ecosystem function. However, the importance of intraspecific genetic variation and diversity to floral abundance and pollinator visitation has received little attention. METHODOLOGY/PRINCIPAL FINDINGS: Using an experimental common garden that manipulated genotypic diversity (the number of distinct genotypes per plot of Solidago altissima, we document that genotypic diversity of a dominant plant can indirectly influence flower visitor abundance. Across two years, we found that 1 plant genotype explained 45% and 92% of the variation in flower visitor abundance in 2007 and 2008, respectively; and 2 plant genotypic diversity had a positive and non-additive effect on floral abundance and the abundance of flower visitors, as plots established with multiple genotypes produced 25% more flowers and received 45% more flower visits than would be expected under an additive model. CONCLUSIONS/SIGNIFICANCE: These results provide evidence that declines in genotypic diversity may be an important but little considered factor for understanding plant-pollinator dynamics, with implications for the global decline in pollinators due to reduced plant diversity in both agricultural and natural ecosystems.
Full Text Available The aim of the current study was to determine the floral phenology, nectar secretion dynamics, and honey production potentials of two naturally growing lavender species (L. dentata and L. pubescens, in southwestern Saudi Arabia. In both species, flowering is continuous. This means that, when open flowers on a spike are shaded, new flowers emerge. Such a flowering pattern might be advantageous to the plant to minimise competition for pollinators and promote efficient resource allocation. The flowering periods of the two species overlap. Both species secreted increasing amounts of nectar from early morning to late afternoon. The mean maximum volumes of accumulated nectar from bagged flowers occurred at 15:00 for L. pubescens (0.50 ± 0.24 μL/flower and at 18:00 for L. dentata (0.68 ± 0.19 μL/flower. The volume of the nectar that became available between two successive measurements (three-h intervals varied from 0.04 μL/flower to 0.28 μL/flower for L. pubescens and from 0.04 μL/flower to 0.35 μL/ flower for L. dentata, This variation reflects the differences in the dynamics of nectar secretion by these species, and indicates the size of the nectar that may be available for flower visitors at given time intervals. The distribution of nectar secretions appears to be an adaptation of the species to reward pollinators for longer duration. Based on the mean amount of nectar sugar secreted by the plants, the honey production potentials of the species are estimated to be 4973.34 mg and 3463.41 mg honey/plant for L. dentata and L. pubescens, respectively.
Full Text Available Plants of the Glochidion (Phyllanthaceae genus are pollinated exclusively by host-specific Epicephala (Gracillariidae moths. Floral scent has been thought to play key role in the obligate pollination mutualism between Glochidion plants and Epicephala moths, but few studies have been reported about chemical variation in floral volatiles of Glochidion species in China. Floral volatiles of male and female flowers of five Glochidion species in south China were collected by dynamic headspace absorption technique and then were chemically analyzed by using gas chromatography-mass spectrometry. A total of 69 compounds were identified from floral scents of five investigated species. Glochidion hirsutum and G. zeylanicum showed no qualitative differences in floral scent, whereas there were clear variations of floral scent among other species (G. eriocarpum, G. daltonii, and G. sphaerogynum and also they distinctly differed from these two species. Male flowers emitted significantly more scent than female flowers. Glochidion plants exhibited qualitative and quantitative differences in floral scent between two sexes of flowers. The findings suggest that the volatile variation of floral scent among Glochidion species reflects adaptations to specific pollinators. Sexual dimorphism in floral scent has evolved to signal alternative rewards provided by each sex to Epicephala moths.
Yin, Ge; Barrett, Spencer C. H.; Luo, Yi-Bo; Bai, Wei-Ning
Background and Aims Flowering plants display considerable variation in mating system, specifically the relative frequency of cross- and self-fertilization. The majority of estimates of outcrossing rate do not account for temporal variation, particularly during the flowering season. Here, we investigated seasonal variation in mating and fertility in Incarvillea sinensis (Bignoniaceae), an annual with showy, insect-pollinated, ‘one-day’ flowers capable of delayed selfing. We examined the influence of several biotic and abiotic environmental factors on day-to-day variation in fruit set, seed set and patterns of mating. Methods We recorded daily flower number and pollinator abundance in nine 3 × 3-m patches in a population at Mu Us Sand land, Inner Mongolia, China. From marked flowers we collected data on daily fruit and seed set and estimated outcrossing rate and biparental inbreeding using six microsatellite loci and 172 open-pollinated families throughout the flowering period. Key Results Flower density increased significantly over most of the 50-d flowering season, but was associated with a decline in levels of pollinator service by bees, particularly on windy days. Fruit and seed set declined over time, especially during the latter third of the flowering period. Multilocus estimates of outcrossing rate were obtained using two methods (the programs MLTR and BORICE) and both indicated high selfing rates of ∼80 %. There was evidence for a significant increase in levels of selfing as the flowering season progressed and pollinator visitation declined. Biparental inbreeding also declined significantly as the flowering season progressed. Conclusions Temporal variation in outcrossing rates may be a common feature of the mating biology of annual, insect-pollinated plants of harsh environments but our study is the first to examine seasonal mating-system dynamics in this context. Despite having large flowers and showy floral displays, I. sinensis attracted
Meindl, George A; Ashman, Tia-Lynn
Hyperaccumulation is the phenomenon whereby plants take up and sequester in high concentrations elements that generally are excluded from above-ground tissues. It largely is unknown whether the metals taken up by these plants are transferred to floral rewards (i.e., nectar and pollen) and, if so, whether floral visitation is affected. We grew Streptanthus polygaloides, a nickel (Ni) hyperaccumulator, in short-term Ni supplemented soils and control soils to determine whether Ni is accumulated in floral rewards and whether floral visitation is affected by growth in Ni-rich soils. We found that while supplementation of soils with Ni did not alter floral morphology or reward quantity (i.e., anther size or nectar volume), Ni did accumulate in the nectar and pollen-filled anthers-providing the first demonstration that Ni is accumulated in pollinator rewards. Further, S. polygaloides grown in Ni-supplemented soils received fewer visits per flower per hour from both bees and flies (both naïve to Ni-rich floral resources in the study area) relative to plants grown in control soils, although the probability a plant was visited initially was unaffected by Ni treatment. Our findings show that while Ni-rich floral rewards decrease floral visitation, floral visitors are not completely deterred, so some floral visitors may collect and ingest potentially toxic resources from metal-hyperaccumulating plants. In addition to broadening our understanding of the effects of metal accumulation on ecological interactions in natural populations, these results have implications for the use of insect-pollinated plants in phytoremediation.
Kusters, Elske; Della Pina, Serena; Castel, Rob; Souer, Erik; Koes, Ronald
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 changes in the encoded proteins. Here, we report a functional comparison of the promoters of homologous FMI genes from Arabidopsis, petunia, tomato and Antirrhinum. Analysis of promoter-reporter constructs in petunia and Arabidopsis, as well as complementation experiments, showed that the divergent expression of leafy (LFY) and the petunia homolog aberrant leaf and flower (ALF) results from alterations in the upstream regulatory network rather than cis-regulatory changes. The divergent expression of unusual floral organs (UFO) from Arabidopsis, and the petunia homolog double top (DOT), however, is caused by the loss or gain of cis-regulatory promoter elements, which respond to trans-acting factors that are expressed in similar patterns in both species. Introduction of pUFO:UFO causes no obvious defects in Arabidopsis, but in petunia it causes the precocious and ectopic formation of flowers. This provides an example of how a change in a cis-regulatory region can account for a change in the plant body plan.
Dudash, Michele R; Hassler, Cynthia; Stevens, Peter M; Fenster, Charles B
Controversy is ongoing regarding the importance of pollinator-mediated selection as a source of observed patterns of floral diversity. Although increasing evidence exists of pollinator-mediated selection acting on female reproductive success, there is still limited understanding of pollinator-mediated selection on floral traits via male reproductive success. Here we quantify potential selection by the ruby-throated hummingbird, Archilochus colubris, on four floral traits of hermaphroditic Silene exerted through male floral function. In single trait manipulative experiments we quantified hummingbird visitation preference and/or fluorescent dye (a pollen analog) donation as a function of number of flowers displayed (inflorescence size), height of the floral display (inflorescence height), floral color, and corolla tube length. Hummingbirds preferred to visit larger floral displays and floral displays at greater height, likely representing a general pollinator preference for larger, more visible signals and/or greater rewards. In addition, hummingbirds preferred to visit red flowers, and male function was greater in flowers manipulated to have longer corolla tubes. Selection pressures exerted by hummingbirds on S. virginica floral and inflorescence design through male reproductive success are consistent with the contemporary expression of floral traits of S. virginica relative to related Silene species with different pollinators, and they are consistent with the hummingbird syndrome of traits expressed by S. virginica.
emissions constitute by far the most significant contribution to the BVOC flux from these tree species, some of which are leafless at this time. Experimental results were integrated into the MEGAN biogenic emission model and simulations were performed to estimate the contribution of floral BVOC emissions to the total urban BVOC flux during the spring flowering period. The floral BVOC emitted during this three-month simulation are equivalent to 11 % of the cumulative monoterpene flux for the Boulder urban area.
Ashley Rae Smith
Full Text Available Natural floral organ degeneration or abortion results in unisexual or fully sterile flowers, while abiotic stresses lead to sterility after initiation of floral reproductive organs. Since normal flower development is essential for plant sexual reproduction and crop yield, it is imperative to have a better understanding of plant sterility under regular and stress conditions. Here, we review the functions of ABC genes together with their downstream genes in floral organ degeneration and the formation of unisexual flowers in Arabidopsis and several agriculturally significant cereal grains. We further explore the roles of hormones, including auxin, brassinosteroids, jasmonic acid, gibberellic acid, and ethylene, in floral organ formation and fertility. We show that alterations in genes affecting hormone biosynthesis, hormone transport and perception cause loss of stamens/carpels, abnormal floral organ development, poor pollen production, which consequently result in unisexual flowers and male/female sterility. Moreover, abiotic stresses, such as heat, cold, and drought, commonly affect floral organ development and fertility. Sterility is induced by abiotic stresses mostly in male floral organ development, particularly during meiosis, tapetum development, anthesis, dehiscence, and fertilization. A variety of genes including those involved in heat shock, hormone signaling, cold tolerance, metabolisms of starch and sucrose, meiosis, and tapetum development are essential for plants to maintain normal fertility under abiotic stress conditions. Further elucidation of cellular, biochemical and molecular mechanisms about regulation of fertility will improve yield and quality for many agriculturally valuable crops.
Eficacia de la terapia floral de Bach aplicada en niños de primer grado con hábito de succión digital Efficacy of Bach´ s flower therapy in first-grade schoolchildren who have the habit of finger sucking.
Mayra Raquel Martínez Ramos
Full Text Available Se realizó un ensayo clínico controlado fase III en 60 niños con hábito de succión digital, entre 6 y 7 años de edad, que recibieron atención primaria en la Clínica Estomatológica Provincial Docente de Santiago de Cuba desde septiembre 2005 a junio 2006, con el objetivo de demostrar la eficacia del tratamiento con terapia floral de Bach para la eliminación del hábito de succión digital. La muestra se seleccionó aleatoriamente y se conformaron 2 grupos de tratamientos: grupo estudio y grupo control, de 30 pacientes cada uno; el primero tratado con terapia floral de Bach y el segundo con tratamiento convencional. Se evaluó a los 7, 15 y 21 días, al 3er, y 6to, mes. Al finalizar el tratamiento se observó que el 66,6 % de niños había eliminado el hábito en el grupo estudio y solo el 20 % en el grupo control. El tratamiento con terapia floral de Bach resultó ser eficaz en la eliminación del hábito de succión digital, por lo que recomendamos extender la aplicación de esta modalidad a otras instituciones estomatológicas de la provincia.A phase III controlled clinical assay was carried out in 60 children aged 6-7 years, who had the habit of finger sucking and were treated in the Provincial Teaching Dental Clinic of Santiago de Cuba province, from September 2005 to June 2006. The objective was to prove the efficacy of Bach´s flower therapy for eliminating finger sucking. The randomly selected sample was divided into 2 groups under treatment, that is, the study group and the control group with 30 patients each; the first received Bach´s therapy and the other the standard treatment. Both groups were evaluated after 7, 15 and 21 days and also at 3rd and 6th months. After completion of treatment, it was observed that 66.6% of children had dropped that habit in the study group whereas only 20% had succeded in the control group. The application of Bach´s flower therapy proved to be effective to elimitate the habit of finger sucking
Under the environment of an artificial climate chamber, supercooling point (SCP) and freezing point (FP) in flower and young fruit at different development stages and freezing injuries of floral organs were studied. The apricot cultivars tested were Kety, Golden Sun and Honghebao. With the development of flower buds, SCP and FP increased, which indicated that their cold resistance decreased. SCP and FP varied with different floral organs. For different apricot cultivars, it was found that, the lower SCP or FP in floral organs was, the more resistant capacity the cultivar had, and the larger the temperature interval from SCP to FP was. SCP was not a constant value, but a range. Frequency distribution of SCP in petals was more dispersing than that in stamens and pistils. Floral organs could maintain a supercooling state to avoid ice formation, but they were sensitive to freezing. Once floral organs froze, they turned brown after thawing.
Rideout, J. W.; Raper, C. D. Jr; Miner, G. S.; Raper CD, J. r. (Principal Investigator)
Under a modification of the nutrient diversion hypothesis, we propose that an inequality in carbohydrate and nitrogen translocation to the apical meristem may be a controlling factor in floral transition. Experiments were conducted in controlled-environment chambers to determine the associations between microscopic characteristics of the transition from vegetative to floral stages of the apical meristem of flue-cured tobacco and to assimilate concentrations in the plant and apical meristem. Low temperature, nitrogen withdrawal, and restriction of nitrogen uptake were used as treatment variables. In all of these stress treatments, flowering occurred at a lesser number of leaves than in control treatments. Low temperature stress accelerated the time of transition to the floral stage as compared with a high temperature control; however, nitrogen stress did not accelerate the time of transition. All stress treatments affected the levels of nitrogen and carbohydrate in whole plants. Most notable was an increase in the percentage of starch and a decrease in the percentage of total soluble carbohydrate induced by the stress treatments. These data indicate that tobacco plants under stress accumulate excess carbohydrate in the form of starch. An apparent inequality in the relative concentrations of carbohydrate and nitrogen in the apical meristem was observed in all treatments at the time of floral transition and is in support of the nutrient diversion hypothesis.
Austen, Emily J; Weis, Arthur E
Our understanding of selection through male fitness is limited by the resource demands and indirect nature of the best available genetic techniques. Applying complementary, independent approaches to this problem can help clarify evolution through male function. We applied three methods to estimate selection on flowering time through male fitness in experimental populations of the annual plant Brassica rapa: (i) an analysis of mating opportunity based on flower production schedules, (ii) genetic paternity analysis, and (iii) a novel approach based on principles of experimental evolution. Selection differentials estimated by the first method disagreed with those estimated by the other two, indicating that mating opportunity was not the principal driver of selection on flowering time. The genetic and experimental evolution methods exhibited striking agreement overall, but a slight discrepancy between the two suggested that negative environmental covariance between age at flowering and male fitness may have contributed to phenotypic selection. Together, the three methods enriched our understanding of selection on flowering time, from mating opportunity to phenotypic selection to evolutionary response. The novel experimental evolution method may provide a means of examining selection through male fitness when genetic paternity analysis is not possible.
Bhosale Sankalp U
Full Text Available Abstract Background Photoperiod-sensitive flowering is a key adaptive trait for sorghum (Sorghum bicolor in West and Central Africa. In this study we performed an association analysis to investigate the effect of polymorphisms within the genes putatively related to variation in flowering time on photoperiod-sensitive flowering in sorghum. For this purpose a genetically characterized panel of 219 sorghum accessions from West and Central Africa was evaluated for their photoperiod response index (PRI based on two sowing dates under field conditions. Results Sorghum accessions used in our study were genotyped for single nucleotide polymorphisms (SNPs in six genes putatively involved in the photoperiodic control of flowering time. Applying a mixed model approach and previously-determined population structure parameters to these candidate genes, we found significant associations between several SNPs with PRI for the genes CRYPTOCHROME 1 (CRY1-b1 and GIGANTEA (GI. Conclusions The negative values of Tajima's D, found for the genes of our study, suggested that purifying selection has acted on genes involved in photoperiodic control of flowering time in sorghum. The SNP markers of our study that showed significant associations with PRI can be used to create functional markers to serve as important tools for marker-assisted selection of photoperiod-sensitive cultivars in sorghum.
Huang, Nien-Chen; Jane, Wann-Neng; Chen, Jychian; Yu, Tien-Shin
Floral initiation is orchestrated by systemic floral activators and inhibitors. This remote-control system may integrate environmental cues to modulate floral initiation. Recently, FLOWERING LOCUS T (FT) was found to be a florigen. However, the identity of systemic floral inhibitor or anti-florigen remains to be elucidated. Here we show that Arabidopsis thaliana CENTRORADIALIS homologue (ATC), an Arabidopsis FT homologue, may act in a non-cell autonomous manner to inhibit floral initiation. Analysis of the ATC null mutant revealed that ATC is a short-day-induced floral inhibitor. Cell type-specific expression showed that companion cells and apex that express ATC are sufficient to inhibit floral initiation. Histochemical analysis showed that the promoter activity of ATC was mainly found in vasculature but under the detection limit in apex, a finding that suggests that ATC may move from the vasculature to the apex to influence flowering. Consistent with this notion, Arabidopsis seedling grafting experiments demonstrated that ATC moved over a long distance and that floral inhibition by ATC is graft transmissible. ATC probably antagonizes FT activity, because both ATC and FT interact with FD and affect the same downstream meristem identity genes APETALA1, in an opposite manner. Thus, photoperiodic variations may trigger functionally opposite FT homologues to systemically influence floral initiation.
Gross, Karin; Sun, Mimi; Schiestl, Florian P.
Geographically structured phenotypic selection can lead to adaptive divergence. However, in flowering plants, such divergent selection has rarely been shown, and selection on floral signals is generally little understood. In this study, we measured phenotypic selection on display size, floral color, and floral scent in four lowland and four mountain populations of the nectar-rewarding terrestrial orchid Gymnadenia odoratissima in two years. We also quantified population differences in these traits and pollinator community composition. Our results show positive selection on display size and positive, negative, or absence of selection on different scent compounds and floral color. Selection on the main scent compounds was consistently stronger in the lowlands than in the mountains, and lowland plants emitted higher amounts of most of these compounds. Pollinator community composition also differed between regions, suggesting different pollinators select for differences in floral volatiles. Overall, our study is the first to document consistent regional differences in selection on floral scent, suggesting this pattern of selection is one of the evolutionary forces contributing to regional divergence in floral chemical signaling. PMID:26886766
Itoh, Hironori; Izawa, Takeshi
The photoperiodic control of flowering time is essential for the adaptation of plants to variable environments and for successful reproduction. The identification of genes encoding florigens, which had been elusive but were supposedly synthesized in leaves and then transmitted to shoot apices to induce floral transitions, has greatly advanced our understanding of the photoperiodic regulation of flowering. Studies on the photoperiodism of Arabidopsis, a model long-day plant, revealed the molecular mechanisms regulating the expression of the Arabidopsis florigen gene FT, which is gradually induced in response to increase in day length. By contrast, in rice, a model short-day plant, the expression of the florigen gene Hd3a (an FT ortholog in rice) is regulated in an on/off fashion, with strong induction under short-day conditions and repression under long-day conditions. This critical day length dependence of Hd3a expression enables rice to recognize a slight change in the photoperiod as a trigger to initiate floral induction. Rice possesses a second florigen gene, RFT1, which can be expressed to induce floral transition under non-inductive long-day conditions. The complex transcriptional regulation of florigen genes and the resulting precise control over flowering time provides rice with the adaptability required for a crop species of increasing global importance.
Shi, Y; Zhang, X; Xu, Z-Y; Li, L; Zhang, C; Schläppi, M; Xu, Z-Q
EARLI1 encodes a 14.7 kDa protein in the cell wall, is a member of the PRP (proline-rich protein) family and has multiple functions, including resistance to low temperature and fungal infection. RNA gel blot analyses in the present work indicated that expression of EARLI1-like genes, EARLI1, At4G12470 and At4G12490, was down-regulated in Col-FRI-Sf2 RNAi plants derived from transformation with Agrobacterium strain ABI, which contains a construct encoding a double-strand RNA targeting 8CM of EARLI1. Phenotype analyses revealed that Col-FRI-Sf2 RNAi plants of EARLI1 flowered earlier than Col-FRI-Sf2 wild-type plants. The average bolting time of Col-FRI-Sf2 and Col-FRI-Sf2 RNAi plants was 39.7 and 19.4 days, respectively, under a long-day photoperiod. In addition, there were significant differences in main stem length, internode number and rosette leaf number between Col-FRI-Sf2 and Col-FRI-Sf2 RNAi plants. RT-PCR showed that EARLI1-like genes might delay flowering time through the autonomous and long-day photoperiod pathways by maintaining the abundance of FLC transcripts. In Col-FRI-Sf2 RNAi plants, transcription of FLC was repressed, while expression of SOC1 and FT was activated. Microscopy observations showed that EARLI1-like genes were also associated with morphogenesis of leaf cells in Arabidopsis. Using histochemical staining, EARLI1-like genes were found to be involved in regulation of lignin synthesis in inflorescence stems, and Col-FRI-Sf2 and Col-FRI-Sf2 RNAi plants had 9.67% and 8.76% dry weight lignin, respectively. Expression analysis revealed that cinnamoyl-CoA reductase, a key enzyme in lignin synthesis, was influenced by EARLI1-like genes. These data all suggest that EARLI1-like genes could control the flowering process and lignin synthesis in Arabidopsis.
Lin, Ming-Kuem; Belanger, Helene; Lee, Young-Jin; Varkonyi-Gasic, Erika; Taoka, Ken-Ichiro; Miura, Eriko; Xoconostle-Cázares, Beatriz; Gendler, Karla; Jorgensen, Richard A; Phinney, Brett; Lough, Tony J; Lucas, William J
Cucurbita moschata, a cucurbit species responsive to inductive short-day (SD) photoperiods, and Zucchini yellow mosaic virus (ZYMV) were used to test whether long-distance movement of FLOWERING LOCUS T (FT) mRNA or FT is required for floral induction. Ectopic expression of FT by ZYMV was highly effective in mediating floral induction of long-day (LD)-treated plants. Moreover, the infection zone of ZYMV was far removed from floral meristems, suggesting that FT transcripts do not function as the florigenic signal in this system. Heterografting demonstrated efficient transmission of a florigenic signal from flowering Cucurbita maxima stocks to LD-grown C. moschata scions. Real-time RT-PCR performed on phloem sap collected from C. maxima stocks detected no FT transcripts, whereas mass spectrometry of phloem sap proteins revealed the presence of Cm-FTL1 and Cm-FTL2. Importantly, studies on LD- and SD-treated C. moschata plants established that Cmo-FTL1 and Cmo-FTL2 are regulated by photoperiod at the level of movement into the phloem and not by transcription. Finally, mass spectrometry of florally induced heterografted C. moschata scions revealed that C. maxima FT, but not FT mRNA, crossed the graft union in the phloem translocation stream. Collectively, these studies are consistent with FT functioning as a component of the florigenic signaling system in the cucurbits.
Jaudal, Mauren; Zhang, Lulu; Che, Chong; Hurley, Daniel G; Thomson, Geoffrey; Wen, Jiangqi; Mysore, Kirankumar S; Putterill, Joanna
Optimising the timing of flowering contributes to successful sexual reproduction and yield in agricultural plants. FLOWERING LOCUS T (FT) genes, first identified in Arabidopsis thaliana (Arabidopsis), promote flowering universally, but the upstream flowering regulatory pathways can differ markedly among plants. Flowering in the model legume, Medicago truncatula (Medicago) is accelerated by winter cold (vernalisation) followed by long day (LD) photoperiods leading to elevated expression of the floral activator, FT-like gene FTa1. However, Medicago, like some other plants, lacks the activator CONSTANS (CO) and the repressor FLOWERING LOCUS C (FLC) genes which directly regulate FT and are key to LD and vernalisation responses in Arabidopsis. Conversely, Medicago has a VERNALISATION2-LIKE VEFS-box gene (MtVRN2). In Arabidopsis AtVRN2 is a key member of a Polycomb complex involved in stable repression of Arabidopsis FLC after vernalisation. VRN2-like genes have been identified in other eudicot plants, but their function has never been reported. We show that Mtvrn2 mutants bypass the need for vernalisation for early flowering in LD conditions in Medicago. Investigation of the underlying mechanism by transcriptome analysis reveals that Mtvrn2 mutants precociously express FTa1 and other suites of genes including floral homeotic genes. Double-mutant analysis indicates that early flowering is dependent on functional FTa1. The broad significance of our study is that we have demonstrated a function for a VRN2-like VEFS gene beyond the Brassicaceae. In particular, MtVRN2 represses the transition to flowering in Medicago by regulating the onset of expression of the potent floral activator, FTa1.
Souza Vidigal, de Deborah; Correia Silva Santana Marques, Alexandre; Willems, Leo A.J.; Buijs, Gonda; Méndez-Vigo, Belén; Hilhorst, Henk W.M.; Bentsink, Leónie; Picó, F.X.; Alonso-Blanco, Carlos
The temporal control or timing of the life cycle of annual plants is presumed to provide adaptive strategies to escape harsh environments for survival and reproduction. This is mainly determined by the timing of germination, which is controlled by the level of seed dormancy, and of flowering init
Allard, Alix; Bink, Marco C.A.M.; Martinez, Sebastien; Kelner, Jean Jacques; Legave, Jean Michel; Guardo, Di Mario; Pierro, Di Erica A.; Laurens, François; De Weg, Van Eric W.; Costes, Evelyne
In temperate trees, growth resumption in spring time results from chilling and heat requirements, and is an adaptive trait under global warming. Here, the genetic determinism of budbreak and flowering time was deciphered using five related full-sib apple families. Both traits were observed over 3
Huo, Heqiang; Wei, Shouhui; Bradford, Kent J.
Seed germination and flowering, two critical developmental transitions in plant life cycles, are coordinately regulated by genetic and environmental factors to match plant establishment and reproduction to seasonal cues. The DELAY OF GERMINATION1 (DOG1) gene is involved in regulating seed dormancy in response to temperature and has also been associated genetically with pleiotropic flowering phenotypes across diverse Arabidopsis thaliana accessions and locations. Here we show that DOG1 can regulate seed dormancy and flowering times in lettuce (Lactuca sativa, Ls) and Arabidopsis through an influence on levels of microRNAs (miRNAs) miR156 and miR172. In lettuce, suppression of LsDOG1 expression enabled seed germination at high temperature and promoted early flowering in association with reduced miR156 and increased miR172 levels. In Arabidopsis, higher miR156 levels resulting from overexpression of the MIR156 gene enhanced seed dormancy and delayed flowering. These phenotypic effects, as well as conversion of MIR156 transcripts to miR156, were compromised in DOG1 loss-of-function mutant plants, especially in seeds. Overexpression of MIR172 reduced seed dormancy and promoted early flowering in Arabidopsis, and the effect on flowering required functional DOG1. Transcript levels of several genes associated with miRNA processing were consistently lower in dry seeds of Arabidopsis and lettuce when DOG1 was mutated or its expression was reduced; in contrast, transcript levels of these genes were elevated in a DOG1 gain-of-function mutant. Our results reveal a previously unknown linkage between two critical developmental phase transitions in the plant life cycle through a DOG1–miR156–miR172 interaction. PMID:27035986
Huo, Heqiang; Wei, Shouhui; Bradford, Kent J
Seed germination and flowering, two critical developmental transitions in plant life cycles, are coordinately regulated by genetic and environmental factors to match plant establishment and reproduction to seasonal cues. The DELAY OF GERMINATION1 (DOG1) gene is involved in regulating seed dormancy in response to temperature and has also been associated genetically with pleiotropic flowering phenotypes across diverse Arabidopsis thaliana accessions and locations. Here we show that DOG1 can regulate seed dormancy and flowering times in lettuce (Lactuca sativa, Ls) and Arabidopsis through an influence on levels of microRNAs (miRNAs) miR156 and miR172. In lettuce, suppression of LsDOG1 expression enabled seed germination at high temperature and promoted early flowering in association with reduced miR156 and increased miR172 levels. In Arabidopsis, higher miR156 levels resulting from overexpression of the MIR156 gene enhanced seed dormancy and delayed flowering. These phenotypic effects, as well as conversion of MIR156 transcripts to miR156, were compromised in DOG1 loss-of-function mutant plants, especially in seeds. Overexpression of MIR172 reduced seed dormancy and promoted early flowering in Arabidopsis, and the effect on flowering required functional DOG1 Transcript levels of several genes associated with miRNA processing were consistently lower in dry seeds of Arabidopsis and lettuce when DOG1 was mutated or its expression was reduced; in contrast, transcript levels of these genes were elevated in a DOG1 gain-of-function mutant. Our results reveal a previously unknown linkage between two critical developmental phase transitions in the plant life cycle through a DOG1-miR156-miR172 interaction.
FAN; JinHui; LI; WenQing; DONG; XiuChun; GUO; Wei; SHU; HuaiRui
MADS-box genes are involved in floral organ development. Here we report that an AGL6(Agamous-like 6)-like MADS-box gene, HoAGL6, was isolated from Hyacinthus orientalis L. Expression pattern analysis demonstrated that HoAGL6 transcript was detected in inflorescence buds, tepals, carpels and ovules, but not in stamina, leaves or scales. Transgenic Arabidopsis plants ectopically expressing HoAGL6 exhibited novel phenotypes of significantly reduced plant size, extremely early flowering, and losing inflorescence indeterminacy. In addition, wide homeotic conversion of sepals, petals, and leaves into carpel-like or ovary structures, and disappearance or number reduction of stamens in 35S::HoAGL6 Arabidopsis plants were also observed. RT-PCR analysis indicated that the expressions of flowering time gene SOC1 and flower meristem identity gene LFY were significantly up-regulated in 35S::HoAGL6 transgenic Arabidopsis plants, and the expression levels of floral organ identity genes AG and SEP1 in leaves were also elevated. These results indicated that HoAGL6 was involved in the regulation of flower transition and flower organ formation.
Flowering is an important developmental event in switchgrass (Panicum virgatum) because the onset of flowering causes the cessation of vegetative growth and biomass accumulation. The objective of this study was to generate a linkage map using single nucleotide polymorphism (SNP) markers to identify ...
Robert E. Farmer
Flowering of Populus deItoides Bartr. occurred from early March to early April; differences between trees within stands accounted for 98 percent of the significant variation in dates. High correlation (r = .91 to .96) between 1963 and 1964 dates of individual trees indicated that trees within stands flower in a predictable sequence. Seed dispersal...
Baumann, Kim; Venail, Julien; Berbel, Ana; Domenech, Maria Jose; Money, Tracy; Conti, Lucio; Hanzawa, Yoshie; Madueno, Francisco; Bradley, Desmond
Models for the control of above-ground plant architectures show how meristems can be programmed to be either shoots or flowers. Molecular, genetic, transgenic, and mathematical studies have greatly refined these models, suggesting that the phase of the shoot reflects different genes contributing to its repression of flowering, its vegetativeness ('veg'), before activators promote flower development. Key elements of how the repressor of flowering and shoot meristem gene TFL1 acts have now been tested, by changing its spatiotemporal pattern. It is shown that TFL1 can act outside of its normal expression domain in leaf primordia or floral meristems to repress flower identity. These data show how the timing and spatial pattern of TFL1 expression affect overall plant architecture. This reveals that the underlying pattern of TFL1 interactors is complex and that they may be spatially more widespread than TFL1 itself, which is confined to shoots. However, the data show that while TFL1 and floral genes can both act and compete in the same meristem, it appears that the main shoot meristem is more sensitive to TFL1 rather than floral genes. This spatial analysis therefore reveals how a difference in response helps maintain the 'veg' state of the shoot meristem. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.
Newman, Ethan; Anderson, Bruce; Johnson, Steven D
Although the tremendous variability in floral colour among angiosperms is often attributed to divergent selection by pollinators, it is usually difficult to preclude the possibility that floral colour shifts were driven by non-pollinator processes. Here, we examine the adaptive significance of flower colour in Disa ferruginea, a non-rewarding orchid that is thought to attract its butterfly pollinator by mimicking the flowers of sympatric nectar-producing species. Disa ferruginea has red flowers in the western part of its range and orange flowers in the eastern part--a colour shift that we hypothesized to be the outcome of selection for resemblance to different local nectar-producing plants. Using reciprocal translocations of red and orange phenotypes as well as arrays of artificial flowers, we found that the butterfly Aeropetes tulbaghia, the only pollinator of the orchid, preferred both the red phenotype and red artificial flowers in the west where its main nectar plant also has red flowers, and both the orange phenotype and orange artificial flowers in the east, where its main nectar plant has orange flowers. This phenotype by environment interaction demonstrates that the flower colour shift in D. ferruginea is adaptive and driven by local colour preference in its pollinator.
Hepworth, Shelley R; Klenz, Jennifer E; Haughn, George W
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.
Fornoni, Juan; Ordano, Mariano; Pérez-Ishiwara, Rubén; Boege, Karina; Domínguez, César A
Floral integration is thought to be an adaptation to promote cross-fertilization, and it is often assumed that it increases morphological matching between flowers and pollinators, increasing the efficiency of pollen transfer. However, the evidence for this role of floral integration is limited, and recent studies have suggested a possible positive association between floral integration and selfing. Although a number of explanations exist to account for this inconsistency, to date there has been no attempt to examine the existence of an association between floral integration and mating system. This study hypothesized that if pollinator-mediated pollen movement among plants (outcrossing) is the main factor promoting floral integration, species with a predominantly outcrossing mating system should present higher levels of floral integration than those with a predominantly selfing mating system. A phylogenetically informed meta-analysis of published data was performed in order to evaluate whether mating system (outcrossing vs. selfing) accounts for the variation in floral integration among 64 species of flowering plants. Morphometric floral information was used to compare intra-floral integration among traits describing sexual organs (androecium and gynoecium) and those corresponding to the perianth (calix and corolla). The analysis showed that outcrossing species have lower floral integration than selfing species. This pattern was caused by significantly higher integration of sexual traits than perianth traits, as integration of the latter group remained unchanged across mating categories. The results suggest that the evolution of selfing is associated with concomitant changes in intra-floral integration. Thus, floral integration of sexual traits should be considered as a critical component of the selfing syndrome. © The Author 2015. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email
Jha, Timir Baran; Saha, Partha Sarathi
The North Eastern Himalayan (NEH) regions of India are considered as one of the major repositories of the "Capsicum annuum complex" which comprises of three cultivated species namely C. annuum, C. frutescens, and C. chinense. The interspecific delimitation within this large complex is ill-defined due to poorly developed crossing barriers and lack of discontinuous morphological characters. The present study elucidates the relationship among nine different cultivars of three Capsicum species on the basis of floral morphology and karyological parameters for the first time. Different floral characteristics such as margins and constrictions of calyx, type of pedicel, flower size, and color were found to have paramount importance in the species delimitation within the studied members of "C. annuum complex." The present karyomorphometric study explicitly revealed differences between the observed chromosomal data such as karyotype formulae, ordering of satellite bearing chromosome pairs and total diploid chromatin length which aid in resolving interspecific relationship among the studied cultivars of Capsicum. The present analyses unambiguously distinguished all cultivars of C. annuum from the members of C. frutescens and C. chinense and also proposed that among the five cultivars of C. annuum, Ghee lanka was comparatively distant from the other four cultivars on the basis of their karyomorphological characteristics. For the first time karyotype of hottest Indian chili is included in this paper. Comprehensive knowledge on floral morphology and karyotypes of some Himalayan Capsicums not only help to conserve genetic diversity but also help capsicum breeders for their basic and applied research.
Li, Feng; Sun, Jinjing; Wang, Donghui; Bai, Shunong; Clarke, Adrian K; Holm, Magnus
Flowering at the appropriate time is crucial for reproductive success and is strongly influenced by various pathways such as photoperiod, circadian clock, FRIGIDA and vernalization. Although each separate pathway has been extensively studied, much less is known about the interactions between them. In this study we have investigated the relationship between the photoperiod/circadian clock gene and FRIGIDA/FLC by characterizing the function of the B-box STO gene family. STO has two B-box Zn-finger domains but lacks the CCT domain. Its expression is controlled by circadian rhythm and is affected by environmental factors and phytohormones. Loss and gain of function mutants show diversiform phenotypes from seed germination to flowering. The sto-1 mutant flowers later than the wild type (WT) under short day growth conditions, while over-expression of STO causes early flowering both in long and short days. STO over-expression not only reduces FLC expression level but it also activates FT and SOC1 expression. It also does not rely on the other B-box gene CO or change the circadian clock system to activate FT and SOC1. Furthermore, the STO activation of FT and SOC1 expression is independent of the repression of FLC; rather STO and FLC compete with each other to regulate downstream genes. Our results indicate that photoperiod and the circadian clock pathway gene STO can affect the key flowering time genes FLC and FT/SOC1 separately, and reveals a novel perspective to the mechanism of flowering regulation.
Rosas-Guerrero, Víctor; Quesada, Mauricio; Armbruster, W Scott; Pérez-Barrales, Rocío; Smith, Stacey DeWitt
Natural selection should reduce phenotypic variation and increase integration of floral traits involved in placement of pollen grains on stigmas. In this study, we examine the role of pollinators and breeding system on the evolution of floral traits by comparing the patterns of floral phenotypic variances and covariances in 20 Ipomoea species that differ in their level of pollination specialization and pollinator dependence incorporating phylogenetic relatedness. Plants with specialized pollination (i.e., those pollinated by one functional group or by few morphospecies) displayed less phenotypic variation and greater floral integration than generalist plants. Self-compatible species also displayed greater floral integration than self-incompatible species. Floral traits involved in pollen placement and pick up showed less variation and greater integration than floral traits involved in pollinator attraction. Analytical models indicate that both breeding system and the number of morphospecies had significant effects on floral integration patterns although only differences in the former were significant after accounting for phylogeny. These results suggest that specialist/self-compatible plants experience more consistent selection on floral traits than generalist/self-incompatible plants. Furthermore, pollinators and breeding system promote integration of floral traits involved in pollen placement and pick up rather than integration of the whole flower. © 2010 The Author(s). Evolution© 2010 The Society for the Study of Evolution.
McArt, Scott H; Koch, Hauke; Irwin, Rebecca E; Adler, Lynn S
Several floral microbes are known to be pathogenic to plants or floral visitors such as pollinators. Despite the ecological and economic importance of pathogens deposited in flowers, we often lack a basic understanding of how floral traits influence disease transmission. Here, we provide the first systematic review regarding how floral traits attract vectors (for plant pathogens) or hosts (for animal pathogens), mediate disease establishment and evolve under complex interactions with plant mutualists that can be vectors for microbial antagonists. Attraction of floral visitors is influenced by numerous phenological, morphological and chemical traits, and several plant pathogens manipulate floral traits to attract vectors. There is rapidly growing interest in how floral secondary compounds and antimicrobial enzymes influence disease establishment in plant hosts. Similarly, new research suggests that consumption of floral secondary compounds can reduce pathogen loads in animal pollinators. Given recent concerns about pollinator declines caused in part by pathogens, the role of floral traits in mediating pathogen transmission is a key area for further research. We conclude by discussing important implications of floral transmission of pathogens for agriculture, conservation and human health, suggesting promising avenues for future research in both basic and applied biology. © 2014 John Wiley & Sons Ltd/CNRS.
Ducrocq, Sébastien; Madur, Delphine; Veyrieras, Jean-Baptiste; Camus-Kulandaivelu, Létizia; Kloiber-Maitz, Monika; Presterl, Thomas; Ouzunova, Milena; Manicacci, Domenica; Charcosset, Alain
An association study conducted on 375 maize inbred lines indicates a strong relationship between Vgt1 polymorphisms and flowering time, extending former quantitative trait loci (QTL) mapping results. Analysis of allele frequencies in a landrace collection supports a key role of Vgt1 in maize altilatitudinal adaptation. PMID:18430961
Full Text Available It is estimated that world-wide existing germplasm collections contain about 7.4 million accessions of plant genetic resources. Wheat (Triticum and Aegilops represents the biggest group with about 900,000 accessions. One of the largest ex situ genebanks worldwide is located at the Leibniz Institute of Plant Genetics and Crop Plant Research in Gatersleben, Germany. This collection comprises wild and primitive forms, landraces as well as old and more recent cultivars of mainly cereals but also other crops. As on the global scale wheat is the largest group having almost 30,000 accessions. Beside the long term storage and frequent regeneration of the material phenotypic characterisation and evaluation data are collected as a prerequisite for gene identification and mapping. We report the outcome of an association-based mapping study to elucidate the genetic basis of flowering time in winter wheat. A core collection of 96 cultivars was subjected to a genome-wide scan using diversity array technology markers. The same set of accessions had been earlier evaluated for flowering time over six consecutive seasons. Some of the resulting marker-trait associations (MTAs mapped to chromosomal locations in which known major genes affecting flowering time are known to reside. However, most of the MTAs identified genomic locations where no such genes are known to map, so providing new opportunities to exploit genetic variation for flowering time in wheat breeding programmes.
Full Text Available It is estimated that world-wide existing germplasm collections contain about 7.4 million accessions of plant genetic resources. Wheat (Triticum and Aegilops represents the biggest group with about 900,000 accessions. One of the largest ex situ genebanks worldwide is located at the Leibniz Institute of Plant Genetics and Crop Plant Research in Gatersleben, Germany. This collection comprises wild and primitive forms, landraces as well as old and more recent cultivars of mainly cereals but also other crops. As on the global scale wheat is the largest group having almost 30,000 accessions. Beside the long term storage and frequent regeneration of the material phenotypic characterisation and evaluation data are collected as a prerequisite for gene identification and mapping. We report the outcome of an association-based mapping study to elucidate the genetic basis of flowering time in winter wheat. A core collection of 96 cultivars was subjected to a genome-wide scan using diversity array technology markers. The same set of accessions had been earlier evaluated for flowering time over six consecutive seasons. Some of the resulting marker-trait associations (MTAs mapped to chromosomal locations in which known major genes affecting flowering time are known to reside. However, most of the MTAs identified genomic locations where no such genes are known to map, so providing new opportunities to exploit genetic variation for flowering time in wheat breeding programmes.
emission rate from crabapple (93 μgC g−1 h−1 during the flowering period is of the same order as isoprene emissions from oak trees, which are among the highest BVOC flowering period floral emissions observed from plants to date. These findings illustrate that during the relatively brief springtime flowering period, floral emissions constitute by far the most significant contribution to the BVOC flux from these tree species, some of which are leafless at this time. Experimental results were integrated into the MEGAN biogenic emission model and simulations were performed to estimate the contribution of floral BVOC emissions to the total urban BVOC flux during the spring flowering period. The floral BVOC emitted during this three-month simulation are equivalent to 11% of the integrated monoterpene flux for the Boulder urban area.
Li, Yuying; Ma, Hong; Wan, Youming; Li, Taiqiang; Liu, Xiuxian; Sun, Zhenghai; Li, Zhenghong
Luculia plants are famed ornamental plants with sweetly fragrant flowers, of which L. pinceana Hooker, found primarily in Yunnan Province, China, has the widest distribution. Solid phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) was employed to identify the volatile organic compounds (VOCs) emitted from different flower development stages of L. pinceana for the evaluation of floral volatile polymorphism. Peak areas were normalized as percentages and used to determine the relative amounts of the volatiles. The results showed that a total of 39 compounds were identified at four different stages of L. pinceana flower development, including 26 at the bud stage, 26 at the initial-flowering stage, 32 at the full-flowering stage, and 32 at the end-flowering stage. The most abundant compound was paeonol (51%-83%) followed by (E,E)-α-farnesene, cyclosativene, and δ-cadinene. All these volatile compounds create the unique fragrance of L. pinceana flower. Floral scent emission offered tendency of ascending first and descending in succession, meeting its peak level at the initial-flowering stage. The richest diversity of floral volatile was detected at the third and later periods of flower development. Principal component analysis (PCA) indicated that the composition and its relative content of floral scent differed throughout the whole flower development. The result has important implications for future floral fragrance breeding of Luculia. L. pinceana would be adequate for a beneficial houseplant and has a promising prospect for development as essential oil besides for a fragrant ornamental owing to the main compounds of floral scent with many medicinal properties.
Full Text Available Luculia plants are famed ornamental plants with sweetly fragrant flowers, of which L. pinceana Hooker, found primarily in Yunnan Province, China, has the widest distribution. Solid phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS was employed to identify the volatile organic compounds (VOCs emitted from different flower development stages of L. pinceana for the evaluation of floral volatile polymorphism. Peak areas were normalized as percentages and used to determine the relative amounts of the volatiles. The results showed that a total of 39 compounds were identified at four different stages of L. pinceana flower development, including 26 at the bud stage, 26 at the initial-flowering stage, 32 at the full-flowering stage, and 32 at the end-flowering stage. The most abundant compound was paeonol (51%–83% followed by (E,E-α-farnesene, cyclosativene, and δ-cadinene. All these volatile compounds create the unique fragrance of L. pinceana flower. Floral scent emission offered tendency of ascending first and descending in succession, meeting its peak level at the initial-flowering stage. The richest diversity of floral volatile was detected at the third and later periods of flower development. Principal component analysis (PCA indicated that the composition and its relative content of floral scent differed throughout the whole flower development. The result has important implications for future floral fragrance breeding of Luculia. L. pinceana would be adequate for a beneficial houseplant and has a promising prospect for development as essential oil besides for a fragrant ornamental owing to the main compounds of floral scent with many medicinal properties.
Terapia floral em gatos domésticos (Felis catus, Linnaeus, 1758 portadores do complexo da doença respiratória felina: estudo clínico e hematológico Flower therapy in domestic cats (Felis catus, Linnaeus, 1758 with feline respiratory disease complex: clinical and hematological study
Full Text Available A terapia floral é considerada, atualmente, prática médica alternativa utilizada em diversas situações clínicas, constituindo possibilidade a mais de prevenção e cura de muitas doenças de natureza física e emocional. Este estudo objetivou pesquisar o efeito das essências do Sistema Brasileiro de Florais Compostos de Joel Aleixo num mesmo grupo de gatos domésticos com sinais clínicos sugestivos de Doença Respiratória Felina (DRF, tratados em diferentes momentos (M0, M1, M2, M3. Foram utilizados 20 gatos domésticos, de ambos os sexos, sem raça definida, com idade média de 5,63 ± 3,02 anos criados em gatil na UFRPE. Os animais foram submetidos ao tratamento com os florais por via oral em duas etapas. Na primeira etapa com os florais Desintus Total e Helminthus Total por 14 dias, e na segunda etapa com os florais Antibius e Regius por 28 dias. Os resultados observados, quanto aos aspectos clínicos, foram redução de secreção nasal, secreção ocular e estertores pulmonares; desaparecimento de sinais clínicos como fezes alteradas, úlceras na cavidade oral, pêlos eriçados e permanência da hipertrofia dos linfonodos. Quanto aos aspectos hematológicos houve interferência nas variáveis relacionadas ao hemograma (hemoglobina, VCM, CHCM, leucócitos, linfócitos e monócitos. Conclui-se que a terapia floral mostrou-se eficaz em gatos domésticos com sinais sugestivos de DRF criados nas mesmas condições de manejo.Flower therapy is currently considered an alternative medical practice used in several clinical situations, providing another way to prevent and cure many diseases of physical and emotional nature. This study aimed to investigate the effect of essences of the Brazilian Compound Flower System of Joel Aleixo in one same group of domestic cats showing suggestive clinical signs of Feline Respiratory Disease (FRD, treated in different moments (M0, M1, M2, M3. Twenty domestic cats, males and females, of mixed breed, with
Anselmi, C; Centini, M; Sega, A; Napolitano, E; Pelosi, P; Scesa, C
Synopsis To provide further information on the relationships between chemical structure and floral odour, here we report the synthesis and the odour evaluation of some spirane derivatives, designed as conformational models of our previously described floral odorants. One of the new compounds (5-methyl-benzo[1,3]dioxole-2-spiro-1-cyclohexane), in particular, is endowed with a particularly pleasant odour of white flowers, can be easily prepared from commercial products and is more stable than other odorants of the same class; these characteristics make this odorant suitable for being used as an additive in perfumery and cosmetics.
Hanna, Cause; Naughton, Ida; Boser, Christina; Alarcón, Ruben; Hung, Keng-Lou James; Holway, David
Ants often visit flowers, but have only seldom been documented to provide effective pollination services. Floral visitation by ants can also compromise plant reproduction in situations where ants interfere with more effective pollinators. Introduced ants may be especially likely to reduce plant reproductive success through floral visitation, but existing experimental studies have found little support for this hypothesis. Here, we combine experimental and observational approaches to examine the importance of floral visitation by the nonnative Argentine ant (Linepithema humile) on plant species native to Santa Cruz Island, California, USA. First, we determine how L. humile affects floral visitor diversity, bee visitation rates, and levels of pollen limitation for the common, focal plant species island morning glory (Calystegia macrostegia ssp. macrostegia). Second, we assess the broader ecological consequences of floral visitation by L. humile by comparing floral visitation networks between invaded and uninvaded sites. The Argentine ant and native ants both visited island morning glory flowers, but L. humile was much more likely to behave aggressively towards other floral visitors and to be the sole floral occupant. The presence of L. humile in morning glory flowers reduced floral visitor diversity, decreased rates of bee visitation, and increased levels of pollen limitation. Network comparisons between invaded and uninvaded. sites revealed differences in both network structure and species-level attributes. In. invaded sites, floral visitors were observed on fewer plant species, ants had a higher per-plant interaction strength relative to that of other visitors, and interaction strengths between bees and plants were weaker. These results illustrate that introduced ants can negatively affect plant reproduction and potentially disrupt pollination services at an ecosystem scale.
Herrera, Carlos M; García, Isabel M; Pérez, Ricardo
The ecology of nectarivorous microbial communities remains virtually unknown, which precludes elucidating whether these organisms play some role in plant-pollinator mutualisms beyond minor commensalism. We simultaneously assessed microbial abundance and nectar composition at the individual nectary level in flowers of three southern Spanish bumble bee-pollinated plants (Helleborus foetidus, Aquilegia vulgaris, and Aquilegia pyrenaica cazorlensis). Yeasts were frequent and abundant in nectar of all species, and variation in yeast density was correlated with drastic changes in nectar sugar concentration and composition. Yeast communities built up in nectar from early to late floral stages, at which time all nectaries contained yeasts, often at densities between 10(4) and 10(5) cells/mm3. Total sugar concentration and percentage sucrose declined, and percentage fructose increased, with increasing density of yeast cells in nectar. Among-nectary variation in microbial density accounted for 65% (H. foetidus and A. vulgaris) and 35% (A. p. cazorlensis) of intraspecific variance in nectar sugar composition, and 60% (H. foetidus) and 38% (A. vulgaris) of variance in nectar concentration. Our results provide compelling evidence that nectar microbial communities can have detrimental effects on plants and/or pollinators via extensive nectar degradation and also call for a more careful interpretation of nectar traits in the future, if uncontrolled for yeasts.
Thoma, Rahere; Chandler, John William
The diversity of angiosperm flowers depends on organ meristy and position. However, the signaling pathways that establish polarity and positional information remain largely unelucidated. Use of the founder-cell marker DORNRÖSCHEN-LIKE (DRNL) in Arabidopsis has recently highlighted the importance of the abaxial-adaxial axis for early floral development. We have extended the use of DRNL::GFP to further characterize floral organogenesis in genotypes that are altered in floral organ meristy or position, including ettin (ett-3) and blade-on-petiole (bop)1-11 bop2-4 double mutants. The creation of supernumery sepals by the splitting of sepal founder-cell populations along an ab-/adaxial axis strengthens the importance of the ab-/adaxial developmental axis in early floral meristem development. Furthermore, we confirm the dependency of the wildtype sequence of sepal initiation on bract suppression and demonstrate that supernumery stamens derive from the imprecise resolution of a ring of DRNL expression. Expression of DRNL in apetala1 (ap1-1) and ap2-8 mutants reflect the altered whorl structure and show that these homeotic genes function upstream of DRNL. Analyzing the dynamism of early floral meristem ontogeny at a fine temporal and spatial resolution in Arabidopsis can reveal mechanisms of organogenesis and is applicable to other species with differing floral body plans in a comparative evolutionary context.
Full Text Available The vast diversity of floral colours in many flowering plant families, paired with the observation of preferences among pollinators, suggests that floral colour may be involved in the process of speciation in flowering plants. While transitions in floral colour have been examined in numerous genera, we have very little information on the consequences of floral colour transitions to the evolutionary success of a clade. Overlaid upon these patterns is the possibility that certain floral colours are more prevalent in certain environments, with the causes of differential diversification being more directly determined by geographical distribution. Here we examine transition rates to anthocyanin + carotenoid rich (red/orange/fuschia flowers and examine whether red/orange flowers are associated with differences in speciation and/or extinction rates in Mimulus. Because it has been suggested that reddish flowers are more prevalent at high elevation, we also examine the macroevolutionary evidence for this association and determine if there is evidence for differential diversification at high elevations. We find that, while red/orange clades have equivalent speciation rates, the trait state of reddish flowers reverts more rapidly to the nonreddish trait state. Moreover, there is evidence for high speciation rates at high elevation and no evidence for transition rates in floral colour to differ depending on elevation.
Gross, Karin; Schiestl, Florian P
Polyploidization, the doubling of chromosome sets, is common in angiosperms and has a range of evolutionary consequences. Newly formed polyploid lineages are reproductively isolated from their diploid progenitors due to triploid sterility, but also prone to extinction because compatible mating partners are rare. Models have suggested that assortative mating and increased reproductive fitness play a key role in the successful establishment and persistence of polyploids. However, little is known about these factors in natural mixed-ploidy populations. This study investigated floral traits that can affect pollinator attraction and efficiency, as well as reproductive success in diploid and tetraploid Gymnadenia conopsea (Orchidaceae) plants in two natural, mixed-ploidy populations. Ploidy levels were determined using flow cytometry, and flowering phenology and herbivory were also assessed. Reproductive success was determined by counting fruits and viable seeds of marked plants. Pollinator-mediated floral isolation was measured using experimental arrays, with pollen flow tracked by means of staining pollinia with histological dye. Tetraploids had larger floral displays and different floral scent bouquets than diploids, but cytotypes differed only slightly in floral colour. Significant floral isolation was found between the two cytotypes. Flowering phenology of the two cytotypes greatly overlapped, and herbivory did not differ between cytotypes or was lower in tetraploids. In addition, tetraploids had higher reproductive success compared with diploids. The results suggest that floral isolation and increased reproductive success of polyploids may help to explain their successful persistence in mixed-ploidy populations. These factors might even initiate transformation of populations from pure diploid to pure tetraploid. © The Author 2015. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email
Antoń, Sebastian; Komoń-Janczara, Elwira; Denisow, Bożena
Main conclusion The floral nectars were sucrose-dominant; however, nectar protein and amino acid contents differed, indicating that composition of nitrogenous compounds may vary considerably even between closely related plant species, irrespectively of nectary structure. Numerous zoophilous plants attract their pollinators by offering floral nectar; an aqueous solution produced by specialized secretory tissues, known as floral nectaries. Although many papers on nectaries and nectar already exist, there has been a little research into the structure of nectaries and/or nectar production and composition in species belonging to the same genus. To redress this imbalance, we sought, in the present paper, to describe the floral nectary, nectar production, and nectar composition in five nocturnal Oenothera species with respect to their floral visitors. The structure of nectaries was similar for all the species investigated, and comprised the epidermis (with nectarostomata), numerous layers of nectary parenchyma, and subsecretory parenchyma. Anthesis for a single flower was short (ca. 10-12 h), and flowers lasted only one night. The release of floral nectar commenced at the bud stage (approx. 4 h before anthesis) and nectar was available to pollinators until petal closure. Nectar concentration was relatively low (ca. 27%) and the nectar was sucrose-dominant, and composed mainly of sucrose, glucose and fructose. The protein content of the nectar was also relatively low (on average, 0.31 µg ml(-1)). Nevertheless, a great variety of amino acids, including both protein and non-protein types, was detected in the nectar profile of the investigated taxa. We noted both diurnal and nocturnal generalist, opportunistic floral insect visitors.
Prolonged exposure to elevated temperature induces floral transition via up-regulation of cytosolic ascorbate peroxidase 1 and subsequent reduction of the ascorbate redox ratio in Oncidium hybrid orchid.
Chin, Dan-Chu; Shen, Chin-Hui; SenthilKumar, Rajendran; Yeh, Kai-Wun
The bolting time of the Oncidium hybrid orchid is not season dependent and so it is a useful year-round model system to study thermal-induced flowering mechanisms in planta. Previously, we reported that a low ascorbate (AsA) content is essential for floral transition in Oncidium; however, the environmental factors governing initiation of the flowering process remained to be elucidated. The current study revealed that a prolonged elevated temperature treatment (30°C over a 14 d period) induces floral transition. This floral induction in response to thermal stress was associated with a significantly increased reactive oxygen species (ROS) level and a lowered AsA redox ratio, as well as prominently up-regulated expression of cytosolic ascorbate peroxidase (cytAPX1). Transcriptome analysis confirmed that increased temperature affected the differential expression of genes involved in antioxidant metabolism. Likewise, transgenic Arabidopsis ectopically overexpressing Oncidium cytAPX1 displayed an early-flowering phenotype and low AsA redox ratio under thermal stress, while cytAPX1 mutants, apx1-1 and apx1-2, exhibited a delayed-flowering phenotype and a high AsA redox ratio. Our present data illustrate that the floral transition response to thermal stress is mediated by the AsA redox ratio, and that CytAPX plays a pivotal role in modulating the AsA redox ratio in Oncidium hybrid orchid. Taken together, the results from this investigation of the thermal-induced flowering mechanism indicated that the AsA redox ratio is a master switch to mediate phase transition from the vegetative to reproductive stage.
The timing of floral transition is critical to reproductive success in angiosperms and is genetically controlled by a network of flowering genes.In Arabidopsis,expression of certain flowering genes is regulated by various chromatin modifications,among which are two central regulators of flowering,namely FLOWERING LOCUS C(FLC) and FLOWERING LOCUS T(FT).Recent studies have revealed that a number of chromatin-modifying components are involved in activation or repression of FLC expression.Activation of FLC expression is associated with various 'active' chromatin modifications including acetylation of core histone tails,histone H3 lysine-4 (H3K4) methylation,H2B monoubiquitination,H3 lysine-36 (H3K36) di- and tri-methylation and deposition of the histone variant H2A.Z,whereas various 'repressive' histone modifications are associated with FLC repression,including histone deacetylation,H3K4 demethylation,histone H3 lysine-9(H3Kg) and H3 lysine-27 (H3K27) methylation,and histone arginine methylation.In addition,recent studies have revealed that Polycomb group gene-mediated transcriptional-silencing mechanism not only represses FLC expression,but also directly represses FT expression.Regulation of FLC expression provides a paradigm for control of the expression of other developmental genes in plants through chromatin mechanisms.
Yu, Lifeng; Patibanda, Varun; Smith, Harley M S
Flowers are determinate shoots comprised of perianth and reproductive organs displayed in a whorled phyllotactic pattern. Floral organ identity genes display region-specific expression patterns in the developing flower. In Arabidopsis, floral organ identity genes are activated by LEAFY (LFY), which functions with region-specific co-regulators, UNUSUAL FLORAL ORGANS (UFO) and WUSCHEL (WUS), to up-regulate homeotic genes in specific whorls of the flower. PENNYWISE (PNY) and POUND-FOOLISH (PNF) are redundant functioning BELL1-like homeodomain proteins that are expressed in shoot and floral meristems. During flower development, PNY functions with a co-repressor complex to down-regulate the homeotic gene, AGAMOUS (AG), in the outer whorls of the flower. However, the function of PNY as well as PNF in regulating floral organ identity in the central whorls of the flower is not known. In this report, we show that combining mutations in PNY and PNF enhance the floral patterning phenotypes of weak and strong alleles of lfy, indicating that these BELL1-like homeodomain proteins play a role in the specification of petals, stamens and carpels during flower development. Expression studies show that PNY and PNF positively regulate the homeotic genes, APETALA3 and AG, in the inner whorls of the flower. Moreover, PNY and PNF function in parallel with LFY, UFO and WUS to regulate homeotic gene expression. Since PNY and PNF interact with the KNOTTED1-like homeodomain proteins, SHOOTMERISTEMLESS (STM) and KNOTTED-LIKE from ARABIDOPSIS THALIANA2 (KNAT2) that regulate floral development, we propose that PNY/PNF-STM and PNY/PNF-KNAT2 complexes function in the inner whorls to regulate flower patterning events.
Yan, Juan; Wang, Gang; Sui, Yi; Wang, Menglin; Zhang, Ling
Floral colour change is visual signals for pollinators to avoid old flowers and increase pollination efficiency. Quisqualis indica flowers change colour from white to pink to red may be associated with a shift from moth to butterfly pollination. To test this hypothesis, we investigated Q. indica populations in Southwest China. Flowers secreted nectar continuously from the evening of anthesis until the following morning, then decreased gradually with floral colour change. The scent compounds in the three floral colour stages were similar; however, the scent composition was different, and the scent emission rate decreased from the white to red stage. Dichogamy in Q. indica prevents self-pollination and interference of male and female functions. Controlled pollinations demonstrated that this species is self-incompatible and needs pollinators for seed production. Different pollinators were attracted in each floral colour stage; mainly moths at night and bees and butterflies during the day. Observations of open-pollinated inflorescences showed that white flowers had a higher fruit set than pink or red flowers, indicating the high contribution of moths to reproductive success. We concluded that the nectar and scent secretion are related to floral colour change in Q. indica, in order to attract different pollinators and promote reproductive fitness.
Olson, Mark E
Floral morphology of the 13 species of Moringa ranges from actinomorphic flowers with little hypanthium to highly zygomorphic flowers with well-developed hypanthia. Scanning electron and light microscopy were used to identify ontogenetic differences among two actinomorphic and eight zygomorphic species. All species show traces of zygomorphy between petal organogenesis and anther differentiation. At late organogenesis, zygomorphy is manifest by one petal being larger than the others, slight unidirectional maturation of the anthers, and in many species, some staminodes may be missing. At organ differentiation and beyond, the actinomorphic species show a trend toward increasing actinomorphy, whereas the zygomorphic features of early ontogeny are progressively accentuated throughout the ontogeny of the zygomorphic species. Because of the early traces of zygomorphy throughout the family, ontogeny in Moringa does not resemble that known from the sister taxon Caricaceae, which has flowers that are actinomorphic throughout ontogeny. Great intraspecific variation was found in floral plan in the actinomorphic-flowered species in contrast to the zygomorphic species. Each of the main clades in the family is distinguished by at least one feature of floral ontogeny. In general, ontogenetic differences that are congruent with deeper phylogenetic splits tend to occur earlier in ontogeny than those congruent with more recent divergences.
Full Text Available Rice is a facultative short-day plant (SDP, and the regulatory pathways for flowering time are conserved, but functionally modified, in Arabidopsis and rice. Heading date 1 (Hd1, an ortholog of Arabidopsis CONSTANS (CO, is a key regulator that suppresses flowering under long-day conditions (LDs, but promotes flowering under short-day conditions (SDs by influencing the expression of the florigen gene Heading date 3a (Hd3a. Another key regulator, Early heading date 1 (Ehd1, is an evolutionarily unique gene with no orthologs in Arabidopsis, which acts as a flowering activator under both SD and LD by promoting the rice florigen genes Hd3a and RICE FLOWERING LOCUST 1 (RFT1. Here, we report the isolation and characterization of the flowering regulator Heading Date Repressor1 (HDR1 in rice. The hdr1 mutant exhibits an early flowering phenotype under natural LD in a paddy field in Beijing, China (39°54'N, 116°23'E, as well as under LD but not SD in a growth chamber, indicating that HDR1 may functionally regulate flowering time via the photoperiod-dependent pathway. HDR1 encodes a nuclear protein that is most active in leaves and floral organs and exhibits a typical diurnal expression pattern. We determined that HDR1 is a novel suppressor of flowering that upregulates Hd1 and downregulates Ehd1, leading to the downregulation of Hd3a and RFT1 under LDs. We have further identified an HDR1-interacting kinase, OsK4, another suppressor of rice flowering under LDs. OsK4 acts similarly to HDR1, suppressing flowering by upregulating Hd1 and downregulating Ehd1 under LDs, and OsK4 can phosphorylate HD1 with HDR1 presents. These results collectively reveal the transcriptional regulators of Hd1 for the day-length-dependent control of flowering time in rice.
Sun, Xuehui; Zhang, Zhiguo; Wu, Jinxia; Cui, Xuean; Feng, Dan; Wang, Kai; Xu, Ming; Zhou, Li; Han, Xiao; Gu, Xiaofeng; Lu, Tiegang
Rice is a facultative short-day plant (SDP), and the regulatory pathways for flowering time are conserved, but functionally modified, in Arabidopsis and rice. Heading date 1 (Hd1), an ortholog of Arabidopsis CONSTANS (CO), is a key regulator that suppresses flowering under long-day conditions (LDs), but promotes flowering under short-day conditions (SDs) by influencing the expression of the florigen gene Heading date 3a (Hd3a). Another key regulator, Early heading date 1 (Ehd1), is an evolutionarily unique gene with no orthologs in Arabidopsis, which acts as a flowering activator under both SD and LD by promoting the rice florigen genes Hd3a and RICE FLOWERING LOCUST 1 (RFT1). Here, we report the isolation and characterization of the flowering regulator Heading Date Repressor1 (HDR1) in rice. The hdr1 mutant exhibits an early flowering phenotype under natural LD in a paddy field in Beijing, China (39°54'N, 116°23'E), as well as under LD but not SD in a growth chamber, indicating that HDR1 may functionally regulate flowering time via the photoperiod-dependent pathway. HDR1 encodes a nuclear protein that is most active in leaves and floral organs and exhibits a typical diurnal expression pattern. We determined that HDR1 is a novel suppressor of flowering that upregulates Hd1 and downregulates Ehd1, leading to the downregulation of Hd3a and RFT1 under LDs. We have further identified an HDR1-interacting kinase, OsK4, another suppressor of rice flowering under LDs. OsK4 acts similarly to HDR1, suppressing flowering by upregulating Hd1 and downregulating Ehd1 under LDs, and OsK4 can phosphorylate HD1 with HDR1 presents. These results collectively reveal the transcriptional regulators of Hd1 for the day-length-dependent control of flowering time in rice.
Full Text Available To describe plant phenological patterns and correlate functioning for the quantity and quality of resources available for the pollinator, it is crucial to understand the temporal dynamics of biological communities. In this way, the pollination syndromes of 46 species with different growth habits (trees, shrubs, herbs, and vines were examined in an area of Caatinga vegetation, northeastern Brazil (7° 28′ 45″ S and 36° 54′ 18″ W, during two years. Flowering was monitored monthly in all the species, over two years (from January 2003 to December 2004. Pollination syndromes were characterised based on floral traits such as size, colour, morphology, symmetry, floral resources, as well as on direct visual observation of floral visitors on focal plants and published information. We observed differences among the plant growth habits with respect to floral traits, types of resources offered, and floral syndromes. The flowering periods of the species varied among floral syndrome groups. The majority of the melittophilous species flowered during the rainy season in the two study years, while the species of the other pollination syndroms flowered at the end of the dry season. An asynchrony of flowering was noted among the chiropterophilous species, while the phalenophilous group concentrated during the rainy season. The overall availability of floral resources was different during the rainy and the dry seasons, and also it varied among plants with different growth habits. The availability of oil-flowers coincided with the period of low nectar availability. We observed a relationship between the temporal distribution of the pollination syndromes and the availability of floral resources among each growth habits in this tropical ecosystem. Resource allocation in seasonal environments, such as the Caatinga, can function as a strategy for maintaining pollinators, facilitating therefore the reproductive success of plant species. The availability of
Quirino, Z G M; Machado, I C
To describe plant phenological patterns and correlate functioning for the quantity and quality of resources available for the pollinator, it is crucial to understand the temporal dynamics of biological communities. In this way, the pollination syndromes of 46 species with different growth habits (trees, shrubs, herbs, and vines) were examined in an area of Caatinga vegetation, northeastern Brazil (7° 28' 45″ S and 36° 54' 18″ W), during two years. Flowering was monitored monthly in all the species, over two years (from January 2003 to December 2004). Pollination syndromes were characterised based on floral traits such as size, colour, morphology, symmetry, floral resources, as well as on direct visual observation of floral visitors on focal plants and published information. We observed differences among the plant growth habits with respect to floral traits, types of resources offered, and floral syndromes. The flowering periods of the species varied among floral syndrome groups. The majority of the melittophilous species flowered during the rainy season in the two study years, while the species of the other pollination syndroms flowered at the end of the dry season. An asynchrony of flowering was noted among the chiropterophilous species, while the phalenophilous group concentrated during the rainy season. The overall availability of floral resources was different during the rainy and the dry seasons, and also it varied among plants with different growth habits. The availability of oil-flowers coincided with the period of low nectar availability. We observed a relationship between the temporal distribution of the pollination syndromes and the availability of floral resources among each growth habits in this tropical ecosystem. Resource allocation in seasonal environments, such as the Caatinga, can function as a strategy for maintaining pollinators, facilitating therefore the reproductive success of plant species. The availability of floral resources during
Doorn, van W.G.; Dole, I.; Celikel, F.G.; Harkema, H.
Flower opening in Iris (Iris x hollandica) requires elongation of the pedicel and ovary. This moves the floral bud upwards, thereby allowing the tepals to move laterally. Flower opening is requires with elongation of the pedicel and ovary. In cv. Blue Magic, we investigated the possible role of horm
Chen, Gao; Jürgens, Andreas; Shao, Lidong; Liu, Yang; Sun, Weibang; Xia, Chengfeng
By emitting scent resembling that of organic material suitable for oviposition and/or consumption by flies, sapromyophilous flowers use these flies as pollinators. To date, intensive scent analyses of such flowers have been restricted to Apocynaceae, Annonaceae, and Araceae. Recent studies have suggested that the wide range of volatile organic compounds (VOCs) from sapromyophilous flowers play an important role in attracting saprophagous flies by mimicking different types of decomposing substrates (herbivore and carnivore feces, carrion, and the fruiting bodies of fungi, etc.). In this study, we report the flower visitors and the floral VOCs of Stemona japonica (Blume) Miquel, a species native to China. The flowers do not produce rewards, and pollinators were not observed consuming pollen, thus suggesting a deceptive pollination system. Headspace samples of the floral scent were collected via solid-phase micro-extraction and analysed by gas chromatography coupled with mass spectrometry. Main floral scent compounds were 1-pyrroline (59.2%), 2-methyl-1-butanol (27.2%), and 3-methyl-1-butanol (8.8%), and resulted in a semen-like odor of blooming flowers. The floral constituents of S. japonica were significantly different from those found in previous sapromyophilous plants. An olfaction test indicated that 1-pyrroline is responsible for the semen-like odor in S. japonica flowers. Main flower visitors were shoot flies of the genus Atherigona (Muscidae). Bioassays using a mixture of all identified floral volatiles revealed that the synthetic volatiles can attract Atherigona flies in natural habitats. Our results suggest that the foul-smelling flowers of S. japonica may represent a new type of sapromyophily through scent mimicry.
María José Aranzana
Full Text Available There is currently tremendous interest in the possibility of using genome-wide association mapping to identify genes responsible for natural variation, particularly for human disease susceptibility. The model plant Arabidopsis thaliana is in many ways an ideal candidate for such studies, because it is a highly selfing hermaphrodite. As a result, the species largely exists as a collection of naturally occurring inbred lines, or accessions, which can be genotyped once and phenotyped repeatedly. Furthermore, linkage disequilibrium in such a species will be much more extensive than in a comparable outcrossing species. We tested the feasibility of genome-wide association mapping in A. thaliana by searching for associations with flowering time and pathogen resistance in a sample of 95 accessions for which genome-wide polymorphism data were available. In spite of an extremely high rate of false positives due to population structure, we were able to identify known major genes for all phenotypes tested, thus demonstrating the potential of genome-wide association mapping in A. thaliana and other species with similar patterns of variation. The rate of false positives differed strongly between traits, with more clinal traits showing the highest rate. However, the false positive rates were always substantial regardless of the trait, highlighting the necessity of an appropriate genomic control in association studies.
CHEN Ruiqiang; ZHANG Suzhi; SUN Shulan; CHANG Jianhong; ZUO Jianru
Flowering in higher plants is controlled by both the internal and environmental cues. In Arabidopsis, several major genetic loci have been defined as the key switches to control flowering. The Flowering Locus C (FLC) gene has been shown in the autonomous pathway to inhibit the vegetative-to-reproductive transition. FLC appears to be repressed by Flowering Locus D (FLD), which encodes a component of the histone deacetylase complex. Here we report the identification and characterization of a new mutant allele fld-5. Genetic analysis indicates that fld-5 (in the Wassilewskija background) is allelic to the previously characterized fld-3 and fld-4 (in the Colombia-0 background). Genetic and molecular analyses reveal that fld-5 carries a frame-shift mutation, resulting in a premature termination of the FLD open reading frame. The FLC expression is remarkably increased in fld-5, which presumably attributes to the extremely delayed flowering phenotype of the mutant.
Temeles, Ethan J; Koulouris, Carolyn R; Sander, Sarah E; Kress, W John
Matches between the bills of hummingbirds and the flowers they visit have been interpreted as examples of coadaptation and feeding specialization. Observations of birds feeding at flowers longer or shorter than their bills combined with a lack of experimental evidence for foraging trade-offs, however, fail to support these interpretations. We addressed these inconsistencies by considering a seldom-studied dimension of hummingbird-flower relationships, the shape of bills and flowers, through experiments on the Purple-throated Carib, Eulampis jugularis, and its major food plant, Heliconia, in the eastern Caribbean. Bills of male E. jugularis are considerably shorter and straighter than bills of females. We examined foraging performances and trade-offs during visits to natural heliconias and 34 artificial flowers of differing length and curvature. Supporting predictions based on matches between bill and flower morphology, handling times of females were significantly shorter than those of males at the long, curved flowers of a green morph of H. bihai. Contrary to predictions, handling times of males were not significantly shorter than handling times of females at the short flowers of H. caribaea. At artificial flowers, maximum extraction depths of females were significantly longer than maximum extraction depths of males at all curved flowers, but not at straight flowers. Handling times of females were significantly shorter than handling times of males at the longest artificial flowers for all curvatures, whereas handling times of males were significantly shorter at short, straight, artificial flowers, but only while hover-feeding without a perch. Within each sex, handling times were inversely related to bill length at long flowers for all shapes. Taken together, these performance trade-offs suggest that the long, curved bills of females are adapted for feeding from long, curved flowers, whereas the short bills of males are adapted for hover-feeding from short
Notaguchi, Michitaka; Abe, Mitsutomo; Kimura, Takahiro; Daimon, Yasufumi; Kobayashi, Toshinori; Yamaguchi, Ayako; Tomita, Yuki; Dohi, Koji; Mori, Masashi; Araki, Takashi
Day length perceived by a leaf is a major environmental factor that controls the timing of flowering. It has been believed that a mobile, long-distance signal called florigen is produced in the leaf under inductive day length conditions, and is transported to the shoot apex where it triggers floral morphogenesis. Grafting experiments have shown that florigen is transmissible from a donor plant that has been subjected to inductive day length to an uninduced recipient plant. However, the nature of florigen has long remained elusive. Arabidopsis FLOWERING LOCUS T (FT) is expressed in cotyledons and leaves in response to inductive long days (LDs). FT protein, with a basic region/leucine zipper (bZIP) transcription factor FD, acts in the shoot apex to induce target meristem identity genes such as APETALA1 (AP1) and initiates floral morphogenesis. Recent studies have provided evidence that the FT protein in Arabidopsis and corresponding proteins in other species are an important part of florigen. Our work shows that the FT activity, either from overexpressing or inducible transgenes or from the endogenous gene, to promote flowering is transmissible through a graft junction, and that an FT protein with a T7 tag is transported from a donor scion to the apical region of recipient stock plants and becomes detectable within a day or two. The sequence and structure of mRNA are not of critical importance for the long-distance action of the FT gene. These observations led to the conclusion that the FT protein, but not mRNA, is the essential component of florigen.
Milet-Pinheiro, Paulo; Navarro, Daniela Maria do Amaral Ferraz; Dötterl, Stefan; Carvalho, Airton Torres; Pinto, Carlos Eduardo; Ayasse, Manfred; Schlindwein, Clemens
Catasetum is a neotropical orchid genus that comprises about 160 dioecious species with a remarkable sexual dimorphism in floral morphology. Flowers of Catasetum produce perfumes as rewards, which are collected only by male euglossine bees. Currently, floral scents are known to be involved in the selective attraction of specific euglossine species. However, sexual dimorphism in floral scent and its eventual role in the pollination of Catasetum species have never been investigated. Here, we have investigated the pollination of Catasetum uncatum and asked: (1) Is floral scent a sexual dimorphic trait? (2) Does pollinarium removal/deposition affect scent emission? (3) Does sexual dimorphism in floral scent and changed scent emission have implications with regard to the behaviour of the pollinators? The frequency and behaviour of floral visitors were observed in non-manipulated flowers (both flower sexes) and in manipulated flowers (pistillate only) in which pollinaria were deposited. Scents of staminate and pistillate flowers (both manipulated and non-manipulated) were collected by using dynamic headspace methods and analysed chemically. Electrophysiological analyses were performed to detect compounds triggering antennal depolarisation in the euglossine species. C. uncatum is pollinated mainly by males of Euglossa nanomelanotricha. Pollinators were more frequent in pistillate than in staminate inflorescences. Bees approaching staminate flowers frequently flew away without visiting them, a behavioural pattern not observed in pistillate flowers. In the chemical analyses, we recorded 99 compounds, 31 of which triggered antennal depolarisation in pollinators. Multivariate analyses with the electrophysiological-active compounds did not detect differences between the scent composition of staminate and pistillate flowers. Pollinarium removal or deposition resulted in diminished scent emission within 24h in staminate and pistillate flowers, respectively. Surprisingly, bees
Sherwood, J.A.; Debinski, D.M.; Caragea, P.C.; Germino, Matthew
Climate change can have a broad range of effects on ecosystems and organisms, and early responses may include shifts in vegetation phenology and productivity that may not coincide with the energetics and forage timing of higher trophic levels. We evaluated phenology, annual height growth, and foliar frost responses of forbs to a factorial experiment of snow removal (SR) and warming in a high-elevation meadow over two years in the Rocky Mountains, United States. Species included arrowleaf balsamroot (Balsamorhiza sagittata, early-season emergence and flowering) and buckwheat (Eriogonum umbellatum, semi-woody and late-season flowering), key forbs for pollinator and nectar-using animal communities that are widely distributed and locally abundant in western North America. Snow removal exerted stronger effects than did warming, and advanced phenology differently for each species. Specifically, SR advanced green-up by a few days for B. sagittata to >2 wk in E. umbellatum, and led to 5- to 11-d advances in flowering of B. sagittata in one year and advances in bud break in 3 of 4 species/yr combinations. Snow removal increased height of E. umbellatum appreciably (~5 cm added to ~22.8 cm in control), but led to substantial increases in frost damage to flowers of B. sagittata. Whereas warming had no effects on E. umbellatum, it increased heights of B. sagittata by >6 cm (compared to 30.7 cm in control plots) and moreover led to appreciable reductions in frost damage to flowers. These data suggest that timing of snowmelt, which is highly variable from year to year but is advancing in recent decades, has a greater impact on these critical phenological, growth, and floral survival traits and floral/nectar resources than warming per se, although warming mitigated early effects of SR on frost kill of flowers. Given the short growing season of these species, the shifts could cause uncoupling in nectar availability and timing of foraging.
Wilmsen, Saskia; Gottlieb, Robin; Robert R Junker; Lunau, Klaus
Abstract Flower visits are complex encounters, in which animals are attracted by floral signals, guided toward the site of the first physical contact with a flower, land, and finally take up floral rewards. At close range, signals of stamens and pollen play an important role to facilitate flower handling in bees, yet the pollen stimuli eliciting behavioral responses are poorly known. In this study, we test the response of flower?naive bumblebees (Bombus terrestris) toward single and multimoda...
Edward F. Durner
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.
Elena R Alvarez-Buylla
Full Text Available In contrast to the classical view of development as a preprogrammed and deterministic process, recent studies have demonstrated that stochastic perturbations of highly non-linear systems may underlie the emergence and stability of biological patterns. Herein, we address the question of whether noise contributes to the generation of the stereotypical temporal pattern in gene expression during flower development. We modeled the regulatory network of organ identity genes in the Arabidopsis thaliana flower as a stochastic system. This network has previously been shown to converge to ten fixed-point attractors, each with gene expression arrays that characterize inflorescence cells and primordial cells of sepals, petals, stamens, and carpels. The network used is binary, and the logical rules that govern its dynamics are grounded in experimental evidence. We introduced different levels of uncertainty in the updating rules of the network. Interestingly, for a level of noise of around 0.5-10%, the system exhibited a sequence of transitions among attractors that mimics the sequence of gene activation configurations observed in real flowers. We also implemented the gene regulatory network as a continuous system using the Glass model of differential equations, that can be considered as a first approximation of kinetic-reaction equations, but which are not necessarily equivalent to the Boolean model. Interestingly, the Glass dynamics recover a temporal sequence of attractors, that is qualitatively similar, although not identical, to that obtained using the Boolean model. Thus, time ordering in the emergence of cell-fate patterns is not an artifact of synchronous updating in the Boolean model. Therefore, our model provides a novel explanation for the emergence and robustness of the ubiquitous temporal pattern of floral organ specification. It also constitutes a new approach to understanding morphogenesis, providing predictions on the population dynamics of
Plascencia, M; Philpott, S M
In urban landscapes, gardens provide refuges for bee diversity, but conservation potential may depend on local and landscape features. Foraging and population persistence of bee species, as well as overall pollinator community structure, may be supported by the abundance, richness, and spatial distribution of floral resources. Floral resources strongly differ in urban gardens. Using hand netting and pan traps to survey bees, we examined whether abundance, richness, and spatial distribution of floral resources, as well as ground cover and garden landscape surroundings influence bee abundance, species richness, and diversity on the central coast of California. Differences in floral abundance and spatial distribution, as well as urban cover in the landscape, predicted different bee community variables. Abundance of all bees and of honeybees (Apis mellifera) was lower in sites with more urban land cover surrounding the gardens. Honeybee abundance was higher in sites with patchy floral resources, whereas bee species richness and bee diversity was higher in sites with more clustered floral resources. Surprisingly, bee species richness and bee diversity was lower in sites with very high floral abundance, possibly due to interactions with honeybees. Other studies have documented the importance of floral abundance and landscape surroundings for bees in urban gardens, but this study is the first to document that the spatial arrangement of flowers strongly predicts bee abundance and richness. Based on these findings, it is likely that garden managers may promote bee conservation by managing for floral connectivity and abundance within these ubiquitous urban habitats.
Koski, Matthew H; Ashman, Tia-Lynn
Selection driven by biotic interactions can generate variation in floral traits. Abiotic selection, however, also contributes to floral diversity, especially with respect to patterns of pigmentation. Combining comparative studies of floral pigmentation and geography can reveal the bioclimatic factors that may drive macroevolutionary patterns of floral color. We create a molecular phylogeny and measure ultraviolet (UV) floral pattern for 177 species in the Potentilleae tribe (Rosaceae). Species are similar in flower shape and visible color but vary in UV floral pattern. We use comparative approaches to determine whether UV pigmentation variation is associated with geography and/or bioclimatic features (UV-B, precipitation, temperature). Floral UV pattern was present in half of the species, while others were uniformly UV-absorbing. Phylogenetic signal was detected for presence/absence of pattern, but among patterned species, quantitative variation in UV-absorbing area was evolutionarily labile. Uniformly UV-absorbing species tended to experience higher UV-B irradiance. Patterned species occurring at higher altitudes had larger UV-absorbing petal areas, corresponding with low temperature and high UV exposure. This analysis expands our understanding of the covariation of UV-B irradiance and UV floral pigmentation from within species to that among species, and supports the view that abiotic selection is associated with floral diversification among species.
Meng, Jin-Liu; Zhou, Xian-Hui; Zhao, Zhi-Gang; Du, Guo-Zhen
Theory predicts that tighter correlation between floral traits and weaker relationship between floral and vegetative traits more likely occur in specialized flowers than generalized flowers, favoring by precise fit with pollinators. However, traits and trait correlations frequently vary under different environments. Through detecting spatiotemporal variation in phenotypic traits (floral organ size and vegetative size) and trait correlations in four Ranunculaceae species, we examined four predictions. Overall, our results supported these predictions to a certain degree. The mean coefficient of variation (CV) of floral traits in two specialized species (Delphinium kamaonense and Aconitum gymnandrum) was marginally significantly lower than that of another two generalized species (Trollius ranunculoides and Anemone obtusiloba). The two specialized species also showed marginally significantly smaller CV in floral traits than vegetative size across the two species. The absolute mean correlation between floral and vegetative traits, or that between floral traits in species with specialized flowers was not significantly lower, or higher than that in generalized plants, weakly supporting the predictions. Furthermore, we documented a large variation in trait correlations of four species among different seasons and populations. Study of covariance of floral and vegetative traits will benefit from the contrast of results obtained from generalized and specialized pollination systems.
Jin-Liu Meng; Xian-Hui Zhou; Zhi-Gang Zhao; Guo-Zhen Du
Theory predicts that tighter correlation between floral traits and weaker relationship between floral and vegetative traits more likely occur in specialized flowers than generalized flowers,favoring by precise fit with pollinators.However,traits and trait correlations frequently vary under different environments.Through detecting spatiotemporal variation in phenotypic traits (floral organ size and vegetative size) and trait correlations in four Ranunculaceae species,we examined four predictions.Overall,our results supported these predictions to a certain degree.The mean coefficient of variation (CV) of floral traits in two specialized species (Delphinium kamaonense and Aconitum gymnandrum) was marginally significantly lower than that of another two generalized species (Trollius ranunculoides and Anemone obtusiloba).The two specialized species also showed marginally significantly smaller CV in floral traits than vegetative size across the two species.The absolute mean correlation between floral and vegetative traits,or that between floral traits in species with specialized flowers was not significantly lower,or higher than that in generalized plants,weakly supporting the predictions.Furthermore,we documented a large variation in trait correlations of four species among different seasons and populations.Study of covariance of floral and vegetative traits will benefit from the contrast of results obtained from generalized and specialized pollination systems.
Yoo, Mi-Jeong; Chanderbali, André S; Altman, Naomi S; Soltis, Pamela S; Soltis, Douglas E
Current understanding of floral developmental genetics comes primarily from the core eudicot model Arabidopsis thaliana. Here, we explore the floral transcriptome of the basal angiosperm, Nuphar advena (water lily), for insights into the ancestral developmental program of flowers. We identify several thousand Nuphar genes with significantly upregulated floral expression, including homologs of the well-known ABCE floral regulators, deployed in broadly overlapping transcriptional programs across floral organ categories. Strong similarities in the expression profiles of different organ categories in Nuphar flowers are shared with the magnoliid Persea americana (avocado), in contrast to the largely organ-specific transcriptional cascades evident in Arabidopsis, supporting the inference that this is the ancestral condition in angiosperms. In contrast to most eudicots, floral organs are weakly differentiated in Nuphar and Persea, with staminodial intermediates between stamens and perianth in Nuphar, and between stamens and carpels in Persea. Consequently, the predominantly organ-specific transcriptional programs that characterize Arabidopsis flowers (and perhaps other eudicots) are derived, and correlate with a shift towards morphologically distinct floral organs, including differentiated sepals and petals, and a perianth distinct from stamens and carpels. Our findings suggest that the genetic regulation of more spatially discrete transcriptional programs underlies the evolution of floral morphology.
Tiedge, Kira; Lohaus, Gertrud
Floral nectar contains mainly sugars but also amino acids, organic acids, inorganic ions and secondary compounds to attract pollinators. The genus Nicotiana exhibits great diversity among species in floral morphology, flowering time, nectar compositions, and predominant pollinators. We studied nectar samples of 20 Nicotiana species, composed equally of day- and night-flowering plants and attracting different groups of pollinators (e.g. hummingbirds, moths or bats) to investigate whether sugars, amino acids, organic acids and inorganic ions are influenced by pollinator preferences. Glucose, fructose and sucrose were the only sugars found in the nectar of all examined species. Sugar concentration of the nectar of day-flowering species was 20% higher and amino acid concentration was 2-3-fold higher compared to the nectar of night-flowering species. The sucrose-to-hexose ratio was significantly higher in night-flowering species and the relative share of sucrose based on the total sugar correlated with the flower tube length in the nocturnal species. Flowers of different tobacco species contained varying volumes of nectar which led to about 150-fold higher amounts of total sugar per flower in bat- or sunbird-pollinated species than in bee-pollinated or autogamous species. This difference was even higher for total amino acids per flower (up to 1000-fold). As a consequence, some Nicotiana species invest large amounts of organic nitrogen for certain pollinators. Higher concentrations of inorganic ions, predominantly anions, were found in nectar of night-flowering species. Therefore, higher anion concentrations were also associated with pollinator types active at night. Malate, the main organic acid, was present in all nectar samples but the concentration was not correlated with pollinator type. In conclusion, statistical analyses revealed that pollinator types have a stronger effect on nectar composition than phylogenetic relations. In this context, nectar sugars and amino
Tiedge, Kira; Lohaus, Gertrud
Floral nectar contains mainly sugars but also amino acids, organic acids, inorganic ions and secondary compounds to attract pollinators. The genus Nicotiana exhibits great diversity among species in floral morphology, flowering time, nectar compositions, and predominant pollinators. We studied nectar samples of 20 Nicotiana species, composed equally of day- and night-flowering plants and attracting different groups of pollinators (e.g. hummingbirds, moths or bats) to investigate whether sugars, amino acids, organic acids and inorganic ions are influenced by pollinator preferences. Glucose, fructose and sucrose were the only sugars found in the nectar of all examined species. Sugar concentration of the nectar of day-flowering species was 20% higher and amino acid concentration was 2-3-fold higher compared to the nectar of night-flowering species. The sucrose-to-hexose ratio was significantly higher in night-flowering species and the relative share of sucrose based on the total sugar correlated with the flower tube length in the nocturnal species. Flowers of different tobacco species contained varying volumes of nectar which led to about 150-fold higher amounts of total sugar per flower in bat- or sunbird-pollinated species than in bee-pollinated or autogamous species. This difference was even higher for total amino acids per flower (up to 1000-fold). As a consequence, some Nicotiana species invest large amounts of organic nitrogen for certain pollinators. Higher concentrations of inorganic ions, predominantly anions, were found in nectar of night-flowering species. Therefore, higher anion concentrations were also associated with pollinator types active at night. Malate, the main organic acid, was present in all nectar samples but the concentration was not correlated with pollinator type. In conclusion, statistical analyses revealed that pollinator types have a stronger effect on nectar composition than phylogenetic relations. In this context, nectar sugars and amino
Jiang; Hua; Shan; Guilian; Duan; Xinhui; Bi; Yufen; He; Chenggang
Lucerne( Medicago sativa L.) is a plant of strict allogamy,and its pollination relies on bees mainly. Genetic variations of lucerne floral properties,including receptacle diameter,coronary length,number of flowers per raceme,number of racemes per twig,number of flowers per square metre,percentage of tripped flowers,nectar production,sugar concentration in nectar and contents of sucrose,fructose and glucose in nectar,have been studied with morphological markers,and floral properties of ten lucerne cultivars were also investigated to determine their role in number of visiting bees and to provide a basis for the evaluation of mutant flowers for visitation by bees. The results showed CV( coefficient of variation) of floral properties was from 0. 80% to 92. 30%,of which the content of glucose was the most significant one with variation from 0. 01 to 0. 53 μmol /L( P < 0. 05),and the sugar concentration was the most insignificant one( P > 0. 05). The significant order of floral properties affecting the number of visiting bees was that the nectar production per square metre( r = 0. 93,P < 0. 01) was in the first place,followed by the number of flowers per square metre( r = 0. 92,P < 0. 01),sucrose concentration of nectar sugar( r = 0. 82,P < 0. 05),coronary length( r = 0. 77,P < 0. 05) and nectar production per flower( r = 0. 71,P < 0. 05).
Background It is estimated that floral deception has evolved in at least 7500 species of angiosperms, of which two thirds are orchids. Epipactis veratrifolia (Orchidaceae) is a model system of aphid mimicry as aphidophagous hoverflies lay eggs on false brood sites on their flowers. To understand the evolutionary ecology of floral deception, we investigated the pollination biology of E. veratrifolia across 10 populations in the Eastern Himalayas. We reconstructed the phylogeny of Epipactis and...
Christianini, A V; Forzza, R C; Buzato, S
Shifts in pollen vectors favour diversification of floral traits, and differences in pollination strategies between congeneric sympatric species can contribute to reproductive isolation. Divergence in flowering phenology and selfing could also reduce interspecific crossing between self-compatible species. We investigated floral traits and visitation rates of pollinators of two sympatric Encholirium species on rocky outcrops to evaluate whether prior knowledge of floral characters could indicate actual pollinators. Data on flowering phenology, visitation rates and breeding system were used to evaluate reproductive isolation. Flowering phenology overlapped between species, but there were differences in floral characters, nectar volume and concentration. Several hummingbird species visited flowers of both Encholirium spp., but the endemic bat Lonchophylla bokermanni and an unidentified sphingid only visited E. vogelii. Pollination treatments demonstrated that E. heloisae and E. vogelii were partially self-compatible, with weak pollen limitation to seed set. Herbivores feeding on inflorescences decreased reproductive output of both species, but for E. vogelii the damage was higher. Our results indicate that actual pollinators can be known beforehand through floral traits, in agreement with pollination syndromes stating that a set of floral traits can be associated with the attraction of specific groups of pollinators. Divergence on floral traits and pollinator assemblage indicate that shifts in pollination strategies contribute to reproductive isolation between these Encholirium species, not divergence on flowering phenology or selfing. We suggest that hummingbird pollination might be the ancestral condition in Encholirium and that evolution of bat pollination made a substantial contribution to the diversification of this clade. © 2012 German Botanical Society and The Royal Botanical Society of the Netherlands.
Reginato, Marcelo; Michelangeli, Fabián A
Putative processes related to floral diversification and its relation to speciation are still largely unaccounted for in the Melastomataceae. Leandra s.str. is one of the most diverse lineages of the Neotropical Miconieae and ranks among the ten most diverse groups in the Atlantic Forest. Here, we describe the floral diversity of this lineage in a continuous framework and address several questions related to floral evolution and putative developmental and environmental constraints in its morphology. The morphological data set includes individual size measurements and shape scores (from elliptical Fourier analysis) for hypanthia, petals, stamens and styles. We evaluate whether there is evidence of correlation among these floral structures, shifts and convergent patterns, and association of these traits with elevation. Leandra s.str. flower structures present a strong phylogenetic signal and tend to be conserved among close relatives. The extremes in flower regimes seem to be quite distinct, but non-overlapping discrete flower types are not observed. Overall, the morphology of Leandra s.str. floral structures is correlated, and anther colour and inflorescence architecture correlate with flower structures. Additionally, the rates of species diversification and morphological evolution are correlated in most clades. Although some flower regimes tend to occur in different elevational ranges, no significant association is observed. The general idea that hypanthium-ovary fusion is associated with fruit types in the Melastomataceae does not hold for Leandra s.str., where, instead, hypanthium-ovary fusion seems to be associated with anther shape. The lowest rate of flower morphological change, when compared with species diversification rates, is observed in the clade that possesses the most specialized flowers in the group. While stuck on a single general pollination system, Leandra s.str. seems to be greatly wandering around it, given the flower diversity and convergent
LeVan, Katherine E; Hung, Keng-Lou James; McCann, Kyle R; Ludka, John T; Holway, David A
Mounting evidence indicates that trade-offs between plant defense and reproduction arise not only from resource allocation but also from interactions among mutualists. Indirect costs of plant defense by ants, for example, can outweigh benefits if ants deter pollinators. Plants can dissuade ants from occupying flowers, but such arrangements may break down when novel ant partners infiltrate mutualisms. Here, we examine how floral visitation by ants affects pollination services when the invasive Argentine ant (Linepithema humile) replaces a native ant species in a food-for-protection mutualism with the coast barrel cactus (Ferocactus viridescens), which, like certain other barrel cacti, produces extrafloral nectar. We compared the effects of floral visitation by the Argentine ant with those of the most prevalent native ant species (Crematogaster californica). Compared to C. californica, the Argentine ant was present in higher numbers in flowers. Cactus bees (Diadasia spp.), the key pollinators in this system, spent less time in flowers when cacti were occupied by the Argentine ant compared to when cacti were occupied by C. californica. Presumably as a consequence of decreased duration of floral visits by Diadasia, cacti occupied by L. humile set fewer seeds per fruit and produced fewer seeds overall compared to cacti occupied by C. californica. These data illustrate the importance of mutualist identity in cases where plants balance multiple mutualisms. Moreover, as habitats become increasingly infiltrated by introduced species, the loss of native mutualists and their replacement by non-native species may alter the shape of trade-offs between plant defense and reproduction.
Alvarez-Buylla, Elena R; Benítez, Mariana; Corvera-Poiré, Adriana; Chaos Cador, Álvaro; de Folter, Stefan; Gamboa de Buen, Alicia; Garay-Arroyo, Adriana; García-Ponce, Berenice; Jaimes-Miranda, Fabiola; Pérez-Ruiz, Rigoberto V.; Piñeyro-Nelson, Alma; Sánchez-Corrales, Yara E.
Flowers are the most complex structures of plants. Studies of Arabidopsis thaliana, which has typical eudicot flowers, have been fundamental in advancing the structural and molecular understanding of flower development. The main processes and stages of Arabidopsis flower development are summarized to provide a framework in which to interpret the detailed molecular genetic studies of genes assigned functions during flower development and is extended to recent genomics studies uncovering the ke...
Sakai, Shoko; Kawakita, Atsushi; Ooi, Kazuyuki; Inoue, Tamiji
Diversification of floral traits in angiosperms is often attributed to have been driven by adaptations to pollinators. Nevertheless, phylogenetic studies on the relationships among evolutionary changes in floral traits and pollination systems are still limited. We examined the relationships between floral trait changes and pollinator shifts in Bornean gingers (Zingiberaceae). These plants have strongly zygomorphic flowers pollinated by spiderhunter birds, bees of the genus Amegilla, and halictid bees. • We identified pollination systems through field observations and recorded petal color, quantity of floral rewards, and seven measures of flower morphology in 28 ginger species. Phylogenetic trees were constructed from nucleotide sequences of the matK and ITS regions. We examined the correlations between the evolution of pollination systems and floral traits using phylogenetically independent contrasts. • Significant association was found between pink color and spiderhunter pollination, orange and Amegilla pollination, and yellow and white and halictid pollination. Sugar production was higher in spiderhunter-pollinated species and lower in halictid-pollinated. Meanwhile, there was a significant association only for a subset of the floral morphological characters measured. Floral tube length, which is often thought to evolve to match the lengths of pollinator probing apparatuses, did not show any correlation. • There is considerable variation in the strength of association among pollination systems and floral traits. Lack of significant correlation in some traits could partly be explained by floral functions other than pollination, such as adaptations to prevent herbivore damage to the ovules. Further studies on these factors may improve understanding of plant-pollinator interactions.
Leeggangers, Hendrika A.C.F.
The ornamental geophyte Tulipa gesneriana is the most cultivated bulbous species in the Netherlands. It is widely grown in the field for vegetative propagation purposes and in greenhouses for the production of high quality cut flowers. Over the last decade, the tulip bulb industry is affected by the
Karolyi, Florian; Morawetz, Linde; Colville, Jonathan F.; Handschuh, Stephan; Metscher, Brian D.; Krenn, Harald W.
A well-developed suction pump in the head represents an important adaptation for nectar-feeding insects, such as Hymenoptera, Lepidoptera and Diptera. This pumping organ creates a pressure gradient along the proboscis, which is responsible for nectar uptake. The extremely elongated proboscis of the genus Prosoeca (Nemestrinidae) evolved as an adaptation to feeding from long, tubular flowers. According to the functional constraint hypothesis, nectar uptake through a disproportionately elongated, straw-like proboscis increases flower handling time and consequently lowers the energy intake rate. Due to the conspicuous length variation of the proboscis of Prosoeca, individuals with longer proboscides are hypothesised to have longer handling times. To test this hypothesis, we used field video analyses of flower-visiting behaviour, detailed examinations of the suction pump morphology and correlations of proboscis length with body length and suction pump dimensions. Using a biomechanical framework described for nectar-feeding Lepidoptera in relation to proboscis length and suction pump musculature, we describe and contrast the system in long-proboscid flies. Flies with longer proboscides spent significantly more time drinking from flowers. In addition, proboscis length and body length showed a positive allometric relationship. Furthermore, adaptations of the suction pump included an allometric relationship between proboscis length and suction pump muscle volume and a combination of two pumping organs. Overall, the study gives detailed insight into the adaptations required for long-proboscid nectar feeding, and comparisons with other nectar-sucking insects allow further considerations of the evolution of the suction pump in insects with sucking mouthparts.
Full Text Available Insects use several different senses to forage on flowers, and detect floral cues such as color, shape, pattern, humidity and chemical volatiles. This presentation will present our discovery of a previously unappreciated sensory capacity in bumblebees (Bombus terrestris: the detection of floral electric fields. We show that these floral fields act as informational cues, and that they can be affected by the visit of naturally electrically charged bees. Like visual cues, floral electric fields exhibit variations in pattern and structure, which can be discriminated by bumblebees. We also show that such electric field information contributes to the complex array of floral cues that together improve a pollinator’s memory of floral rewards. Floral electric fields arise from complex interactions with the surrounding atmosphere, an interaction between plants and their environment that not well understood. Because floral electric fields can change within seconds, this new sensory modality - electrostatic field detection- may facilitate rapid and dynamic communication between flowers and their pollinators.
Diversity, distribution and floral specificity of tangle-veined flies (Diptera: Nemestrinidae in north west Patagonia, Argentina Diversidad, distribución y especificidad floral de nemestrínidos (Diptera en el noroeste de la Patagonia, Argentina
Full Text Available Tangle-veined flies (Nemestrinidae constitute a primitive and rather widespread family among Diptera. The genus Trichophthalma occurs in Australia and South America and is the only one in the family with a typically Gondwanian, disjoint distribution. The ecology and distribution of most southern South American species of this genus remains virtually unknown. We studied the diversity, distribution and flower specificity of flower-visiting species of the genus Trichophthalma in the temperate forests of southern South America in ten sites along an east-west rainfall gradient (37-40°S on the eastern slope of the Andes. We recorded nine species of Trichophthalma, which showed an overlapped distribution along the gradient and different degrees of floral specificity. Three species are reported for Argentina for the first time and three are first recorded as flower visitors to the local flora. Our results show that while in southern Africa tangle-veined flies are engaged in highly specialized pollination interactions with long-tubed species, the Trichophthalma spp. of Patagonia share their flowers with a diverse and rather unspecialized visitor fauna among which several species of flies, bees and birds are presentLos nemestrínidos constituyen una familia de Dípteros primitiva y de amplia distribución. El género Trichophthalma se encuentra en Australia y Sudamérica y es el único en la familia con una distribución disjunta típicamente gondwánica. La ecología y distribución de la mayoría de las especies sudamericanas permanecen virtualmente desconocidas. Estudiamos la diversidad, distribución y especificidad floral de las especies del género Trichophthalma de los bosques templados del sur de Sudamérica en diez sitios ubicados a lo largo de un gradiente de precipitación este-oeste (37-40°S sobre la vertiente occidental de los Andes. Registramos nueve especies de Trichophthalma, las cuales mostraron una distribución superpuesta a lo largo
Cristian Adrian Martínez-Adriano
Full Text Available We characterized variations in Cordia boissieri flowers and established if these variations occur between plants or between flowering events. Flowering and fruiting was measured for 256 plants. A GLM test was used to determine the relationship between flowering and fruit set processes and rainfall. We performed measurements of floral traits to detect variations within the population and between flowering events. The position of the anthers with respect to the ovary was determined in 1,500 flowers. Three out of four flowering events of >80% C. boissieri plants occurred after rainfall events. Only one flowering event occurred in a drought. Most plants flowered at least twice a year. The overlapping of flowering and fruiting only occurred after rainfall. Anthesis lasted three-to-five days, and there were two flower morphs. Half of the plants had longistylus and half had brevistylus flowers. Anacahuita flower in our study had 1–4 styles; 2–9 stamens; 6.5–41.5 mm long corolla; sepals from 4.5–29.5 mm in length; a total length from 15.5–59 mm; a corolla diameter from 10.5–77 mm. The nectar guide had a diameter from 5–30.5 mm; 4–9 lobes; and 5 distinguishable nectar guide colors. The highest variation of phenotypic expression was observed between plants.
Vahideh Sadat Abbasnia
Full Text Available Background and Aim: In Iranian traditional medicine Citrus Aurantium flower extract is used to treat some neural diseases. Tendency to use medicinal herbs is increasing. The present study was done to determine the effect of Citrus Aurantium flowers on sleeping time and the level of anxiety in mice. Materials and Methods: In this experimental study, 80 male albino mice (25-30 g were randomly divided into 8 equal groups. In order to measure . the sleeping time of the subjects . Angel’s method was applied and the animals were divided into three experimental.groups (200, 400 and 600 mg/kg and one control group. To evaluate their anxiety levels. they were randomly divided into three experimental and one control group;and for their evaluation plus maze (EPM model was used. The evaluation of anxiety indices included number and percent of time spent in open arm. Different doses of the aqueous extract of Citrus Aurantium flowers (200, 400, 600 mg/kg IP; respectively were intraperitoneally injected into the treated groups. But, the controls received 10 ml/kg/BW normal saline intraperitoneally in both of the methods. The obtained data was analyzed by means of SPSS . software (V:17 using one-way ANOVA and Tukey’s test(α=0.05. Results: The extract of Citrus aurantium flowers (200, 400 and 600 mg/kg significantly increased sleeping time (12/2±0/53, (14/4±037, (15/5±1/22, time-spent of open arm entries (64/4±4/01, (75±3/01, (78±2/01 and arm entries into open arms(5/9±021, (6/6±0/41, (6/8±72 compared to the control group (P<0.05. Conclusion: The current study showed that the aqueous extract of Citrus Aurantium flowers incerases the sleeping time and decreases level of anxity in mice.
Notaguchi, Michitaka; Daimon, Yasufumi; Abe, Mitsutomo; Araki, Takashi
Day length perceived by a leaf is a major environmental factor that controls the timing of flowering. It has been believed that a mobile, long-distance signal called florigen is produced in the leaf, and is transported to the shoot apex where it triggers floral morphogenesis. Grafting experiments have shown that florigen is transmissible from a donor plant that has been subjected to inductive day length to an un-induced recipient plant. However, the nature of florigen has long remained elusive. Recent studies have provided evidence that the FLOWERING LOCUS T (FT) protein in Arabidopsis and corresponding proteins in other species are an important part of florigen. Our work showed that the FT activity, either from overexpressing or inducible transgenes or from the endogenous gene, to promote flowering is transmissible through a graft junction, and that an FT protein with a T7 tag (FT-T7) is transported from a donor scion to the apical region of recipient stock plants and becomes detectable within a short period of 24-48 h. That the FT-green fluorescent protein (GFP) fusion protein (FT:GFP) retains limited ability for graft-transmissible action was confirmed.
Roumet, Marie; Cayre, Adeline; Latreille, Muriel; Muller, Marie-Hélène
Flowering time divergence can be a crucial component of reproductive isolation between sympatric populations, but few studies have quantified its actual contribution to the reduction of gene flow. In this study, we aimed at estimating pollen-mediated gene flow between cultivated sunflower and a weedy conspecific sunflower population growing in the same field and at quantifying, how it is affected by the weeds' flowering time. For that purpose, we extended an existing mating model by including a temporal distance (i.e. flowering time difference between potential parents) effect on mating probabilities. Using phenological and genotypic data gathered on the crop and on a sample of the weedy population and its offspring, we estimated an average hybridization rate of approximately 10%. This rate varied strongly from 30% on average for weeds flowering at the crop flowering peak to 0% when the crop finished flowering and was affected by the local density of weeds. Our result also suggested the occurrence of other factors limiting crop-to-weed gene flow. This level of gene flow and its dependence on flowering time might influence the evolutionary fate of weedy sunflower populations sympatric to their crop relative.
Full Text Available Ananas comosus var comosus (L. Merr. is the third most important tropical fruit in the world production and the leading foreign exchange earner among fresh fruits exported from Ghana. A survey was conducted in pineapple farms in the Central region of Ghana to identify floral visitors and their activities on the flowers. Nectar concentration and energetics and effect of floral visitors on fruit production were determined. Fourteen species of butterflies and one ant species were the main insect floral visitors as well as four species of sunbirds. The mean nectar concentration was 23.3% (± 0.39, SE and pollination limitation did not significantly affect fruit yield (weight: p = 0.285; length: p = 0.056; width: p= 0.268. The study showed that butterflies, ants and sunbirds are the main floral visitors on A. comosus. However their visits did not results in pollination and fruit production was not affected in any way by floral visitation. Still, it was found that A. comosus provides an important nectar resource for its foragers. Even if pollination is not crucial in pineapple cultivation, it is still essential in pineapple breeding programs to promote genetic diversity and conservation.
Shrestha, Mani; Dyer, Adrian G; Boyd-Gerny, Skye; Wong, Bob B M; Burd, Martin
Colour signals are a major cue in putative pollination syndromes. There is evidence that the reflectance spectra of many flowers target the distinctive visual discrimination abilities of hymenopteran insects, but far less is known about bird-pollinated flowers. Birds are hypothesized to exert different selective pressures on floral colour compared with hymenopterans because of differences in their visual systems. We measured the floral reflectance spectra of 206 Australian angiosperm species whose floral visitors are known from direct observation rather than inferred from floral characteristics. We quantified the match between these spectra and the hue discrimination abilities of hymenopteran and avian vision, and analysed these metrics in a phylogenetically informed comparison of flowers in different pollination groups. We show that bird-visited flowers and insect-visited flowers differ significantly from each other in the chromatic cues they provide, and that the differences are concentrated near wavelengths of optimal colour discrimination by whichever class of pollinator visits the flowers. Our results indicate that angiosperms have evolved the spectral signals most likely to reinforce their pollinators' floral constancy (the tendency of individual pollinators to visit flowers of the same species) in communities of similarly coloured floral competitors.
YANG Chunfeng; GUO Youhao
Pollination biology provides new insight for understanding the evolutionary mechanism and process of the existing diversity in floral design of angiosperms. Evolutionary biologists have established some rules and models to try to explain the ubiquitous relationship between pollination system and floral evolution. However, as new techniques have been applied and more and more new pollination events found in recent years, the relationship between pollination system and floral evolution has become less clear. Researchers realized that floral evolution is more complicated and idiosyncratic than simple adaptive models. The traditional viewpoints of pollinator mediated floral design urgently need new reevaluation. This paper attempts to make a brief review of such main opinions and introduce their new insights according to recent studies. Finally, we also give some suggestions for future study by reviewing several new viewpoints about floral evolution.
Three Medicago MtFUL genes have distinct and overlapping expression patterns during vegetative and reproductive development and 35S:MtFULb accelerates flowering and causes a terminal flower phenotype in Arabidopsis
Full Text Available The timing of the transition to flowering is carefully controlled by plants in order to optimise sexual reproduction and the ensuing production of seeds, grains and fruits. The genetic networks that regulate floral induction are best characterised in the temperate eudicot Arabidopsis in which the florigen gene FT plays a major role in promoting the transition to flowering. Legumes are an important plant group, but less is known about the regulation of their flowering time. In the model legume Medicago truncatula (Medicago, a temperate annual plant like Arabidopsis, flowering is induced by prolonged cold (vernalisation followed by long day lengths (LD. Recent molecular-genetic experiments have revealed that a FT-like gene, MtFTa1, is a central regulator of flowering time in Medicago. Here, we characterize the three Medicago FRUITFULL (FUL MADS transcription factors, MtFULa, MtFULb and MtFULc using phylogenetic analyses, gene expression profiling through developmental time courses, and functional analyses in transgenic plants. MtFULa and MtFULb have similarity in sequence and expression profiles under inductive environmental conditions during both vegetative and reproductive development while MtFULc is only up regulated in the apex after flowering in LD conditions. Sustained up regulation of MtFULs requires functional MtFTa1 but their transcript levels are not affected during cold treatment. Overexpression of MtFULa and MtFULb promotes flowering in transgenic Arabidopsis plants with an additional terminal flower phenotype on some 35S:MtFULb plants. An increase in transcript levels of the MtFULs was also observed in Medicago plants overexpressing MtFTa1. Our results suggest that the MtFULs are targets of MtFTa1. Overall, this work highlights the conserved functions of FUL-like genes in promoting flowering and other roles in plant development and thus contributes to our understanding of the genetic control of the flowering process in Medicago.
April N. Wynn
Full Text Available The gynoecium is the female reproductive structure of angiosperm flowers. In Arabidopsis thaliana the gynoecium is composed of two carpels fused into a tube-like structure. As the gynoecial primordium arises from the floral meristem, a specialized meristematic structure, the carpel margin meristem (CMM, develops from portions of the medial gynoecial domain. The CMM is critical for reproductive competence because it gives rise to the ovules, the precursors of the seeds. Here we report a functional role for the transcription factor PERIANTHIA (PAN in the development of the gynoecial medial domain and the formation of ovule primordia that is revealed in aintegumenta (ant pan and seuss (seu pan double mutants. Additionally, enhanced disruptions of gynoecial morphology suggest that gynoecial patterning processes are disrupted in the seu pan double mutant. Previously, PAN was identified as a regulator of perianth organ number and as a direct activator of AGAMOUS expression in floral whorl four. However, the seu pan double mutants display enhanced ectopic AG expression in developing sepals and the partial transformation of sepals to petals indicating a novel role for PAN in the repression of AG in floral whorl 1. These results indicate that PAN functions as an activator or repressor of AG expression in a whorl specific fashion. The seu pan double mutants also display enhanced floral indeterminacy, resulting in the formation of fifth whorl structures and disruption of WUS expression patterns revealing a novel role for SEU in floral meristem termination.
The Arboretum in Hørsholm has an extensive collection of woody plant species of known origin. There are approximately 2200 woody plant taxa in the collection, representing 295 genera and 101 plant families. This collection is used to study how plants from different parts of the world thrive...... in response to the Danish environment. In this study of the area within 2 km in all directions from the Arboretum, we found no plant species that were definitely escaping from the Arboretum collection. This was a surprising result, but it became clear that we needed to know if the plants were producing...... flowers (pollen) and fruit (seed) in order to have a clearer understanding of the negative results. As a first step we have begun to record if, and when, the taxa in the collection produce flowers (and thus pollen), and fruits (and thereby seed). In this Working Paper we present and analyse the results...
Full Text Available Abstract Background A controversial topic in evolutionary developmental biology is whether morphological diversification in natural populations can be driven by expansions and contractions of amino acid repeats in proteins. To promote adaptation, selection on protein length variation must overcome deleterious effects of multiple correlated traits (pleiotropy. Thus far, systems that demonstrate this capacity include only ancient or artificial morphological diversifications. The Hawaiian Islands, with their linear geological sequence, present a unique environment to study recent, natural radiations. We have focused our research on the Hawaiian endemic mints (Lamiaceae, a large and diverse lineage with paradoxically low genetic variation, in order to test whether a direct relationship between coding-sequence repeat diversity and morphological change can be observed in an actively evolving system. Results Here we show that in the Hawaiian mints, extensive polyglutamine (CAG codon repeat polymorphism within a homolog of the pleiotropic flowering time protein and abscisic acid receptor FCA tracks the natural environmental cline of the island chain, consequent with island age, across a period of 5 million years. CAG expansions, perhaps following their natural tendency to elongate, are more frequent in colonists of recently-formed, nutrient-rich islands than in their forebears on older, nutrient-poor islands. Values for several quantitative morphological variables related to reproductive investment, known from Arabidopsis fca mutant studies, weakly though positively correlate with increasing glutamine tract length. Together with protein modeling of FCA, which indicates that longer polyglutamine tracts could induce suboptimally mobile functional domains, we suggest that CAG expansions may form slightly deleterious alleles (with respect to protein function that become fixed in founder populations. Conclusion In the Hawaiian mint FCA system, we infer that
Winterhagen, Patrick; Tiyayon, Pimsiri; Samach, Alon; Hegele, Martin; Wünsche, Jens N
Longan (Dimocarpus longan Lour.) is a subtropical evergreen fruit tree, mainly cultivated in Asia. Two putative floral integrator genes, D. longan FLOWERING LOCUS T1 and 2 (DlFT1 and DlFT2) were isolated and both translated sequences revealed a high homology to FT sequences from other plants. Moreover, two APETALA1-like (DlAP1-1 and DlAP1-2) sequences from longan were isolated and characterized. Results indicate that the sequences of these genes are highly conserved, suggesting functions in the longan flowering pathway. Ectopic expression of the longan genes in arabidopsis resulted in different flowering time phenotypes of transgenic plants. Expression experiments reveal a different action of the longan FT genes and indicate that DlFT1 is a flowering promoter, while DlFT2 acts as flowering inhibitor. Overexpression of longan AP1 genes in transgenic arabidopsis results in a range of flowering time phenotypes also including early and late flowering individuals.
Ordas, B; Alvarez, A; Revilla, P; Butron, A; Malvar, R A
In the Mediterranean area, the main corn borer species are Sesamia nonagrioides Lefebvre (Mediterranean corn borer) and Ostrinia nubilalis Hübner (European corn borer). In the overall context of integrated pest control, it is possible to reduce the effect of a pest without having a negative effect on the environment by varying the sowing date. Benefits are possible if the most susceptible stages of the crop no longer coincide with the peak of the pest. We used different cycles of selection (0, 6, 8, 10, and 12) of two populations (Purdue A and Purdue B) of maize selected for early flowering to get a more precise estimation of the relationship between maturity of plant tissues and corn borer damage. We found a relationship between the damage produced by corn borers and the number of days from flowering to infestation. We conclude that, after flowering, a later stage of plant development at the moment of the infestation by corn borers reduces the damage caused by the larvae. Based on our results, we recommend to plant as early as possible so the tissues would be as mature as possible at the moment of insect attack.
Ahmad, I.; Favero, B.T.; Dole, J.M.
Effects of pulsing with different concentrations of gibberellin plus benzyladenine (GA4+7 + BA), a proprietary mixture of GA4+7 plus BA in a commercial floral preservative (GA4+7 + BA + preservative), or a propriety mixture of sugar plus acidifier developed for bulbous flowers (floral bulb...
Chittka, Lars; Thomson, James D.; Waser, Nickolas M.
Individuals of some species of pollinating insects tend to restrict their visits to only a few of the available plant species, in the process bypassing valuable food sources. The question of why this flower constancy exists is a rich and important one with implications for the organization of natural communities of plants, floral evolution, and our understanding of the learning processes involved in finding food. Some scientists have assumed that flower constancy is adaptive per se. Others argued that constancy occurs because memory capacity for floral features in insects is limited, but attempts to identify the limitations often remained rather simplistic. We elucidate now different sensory and motor memories from natural foraging tasks are stored and retrieved, using concepts from modern learning science and visual search, and conclude that flower constancy is likely to have multiple causes. Possible constraints favoring constancy are interference sensitivity of short-term memory, and temporal limitations on retrieving information from long-term memory as rapidly as from short-term memory, but further empirical evidence is needed to substantiate these possibilities. In addition, retrieving memories may be slower and more prone to errors when there are several options than when an insect copes with only a single task. In addition to memory limitations, we also point out alternative explanations for flower constancy. We then consider the way in which floral parameters, such as interplant distances, nectar rewards, flower morphology, and floral color (as seen through bees' eyes) affect constancy. Finally, we discuss the implications of pollinator constancy for plant evolution. To date there is no evidence that flowers have diverged to favor constancy, although the appropriate tests may not have yet been conducted. However, there is good evidence against the notion that pollinator constancy is involved in speciation or maintenance of plant species integrity.
Xie, Zhenghua; Pan, Dongdong; Teichroew, Jonathan; An, Jiandong
Bee species interactions can benefit plant pollination through synergistic effects and complementary effects, or can be of detriment to plant pollination through competition effects by reducing visitation by effective pollinators. Since specific bee interactions influence the foraging performance of bees on flowers, they also act as drivers to regulate the assemblage of flower visitors. We selected squash (Cucurbita pepo L.) and its pollinators as a model system to study the foraging response of honey bees to the occurrence of bumble bees at two types of sites surrounded by a high amount of natural habitats (≥ 58% of land cover) and a low amount of natural habitats (≤ 12% of land cover) in a highland agricultural ecosystem in China. At the individual level, we measured the elapsed time from the departure of prior pollinator(s) to the arrival of another pollinator, the selection of honey bees for flowers occupied by bumble bees, and the length of time used by honey bees to explore floral resources at the two types of sites. At the community level, we explored the effect of bumble bee visitation on the distribution patterns of honey bees on squash flowers. Conclusively, bumble bee visitation caused an increase in elapsed time before flowers were visited again by a honey bee, a behavioral avoidance by a newly-arriving honey bee to select flowers occupied by bumble bees, and a shortened length of time the honey bee takes to examine and collect floral resources. The number of overall bumble bees on squash flowers was the most important factor explaining the difference in the distribution patterns of honey bees at the community level. Furthermore, decline in the number of overall bumble bees on the squash flowers resulted in an increase in the number of overall honey bees. Therefore, our study suggests that bee interactions provide an opportunity to enhance the resilience of ecosystem pollination services against the decline in pollinator diversity.
Full Text Available Bee species interactions can benefit plant pollination through synergistic effects and complementary effects, or can be of detriment to plant pollination through competition effects by reducing visitation by effective pollinators. Since specific bee interactions influence the foraging performance of bees on flowers, they also act as drivers to regulate the assemblage of flower visitors. We selected squash (Cucurbita pepo L. and its pollinators as a model system to study the foraging response of honey bees to the occurrence of bumble bees at two types of sites surrounded by a high amount of natural habitats (≥ 58% of land cover and a low amount of natural habitats (≤ 12% of land cover in a highland agricultural ecosystem in China. At the individual level, we measured the elapsed time from the departure of prior pollinator(s to the arrival of another pollinator, the selection of honey bees for flowers occupied by bumble bees, and the length of time used by honey bees to explore floral resources at the two types of sites. At the community level, we explored the effect of bumble bee visitation on the distribution patterns of honey bees on squash flowers. Conclusively, bumble bee visitation caused an increase in elapsed time before flowers were visited again by a honey bee, a behavioral avoidance by a newly-arriving honey bee to select flowers occupied by bumble bees, and a shortened length of time the honey bee takes to examine and collect floral resources. The number of overall bumble bees on squash flowers was the most important factor explaining the difference in the distribution patterns of honey bees at the community level. Furthermore, decline in the number of overall bumble bees on the squash flowers resulted in an increase in the number of overall honey bees. Therefore, our study suggests that bee interactions provide an opportunity to enhance the resilience of ecosystem pollination services against the decline in pollinator diversity.
Kaufmann, K.; Nagasaki, M.; Jáuregui., R.
We present a dynamical model of the gene network controlling flower development in Arabidopsis thaliana. The network is centered at the regulation of the floral organ identity genes (AP1, AP2, AP3, PI and AG) and ends with the transcription factor complexes responsible for differentiation of floral
The Greek term for flower is Chloris. It is derived from the name of the Chloris, the goddess of vegetation, in Greek mythology, reasonably so, if we consider the great number of mythological tales linked to flowers of the Greek flowers. The use of flowers was widespread in Greece from time immemorial, since flowers are so important to us from the moment we are born. Flowers play an important role in mythology. As they morph from bud to bloom to faded and wilted petals, they assume various meanings linked to youth, life and death. They are associated with goddesses and legends, and are often attributed with certain powers and symbolism.
Hicks, Damien M; Ouvrard, Pierre; Baldock, Katherine C R; Baude, Mathilde; Goddard, Mark A; Kunin, William E; Mitschunas, Nadine; Memmott, Jane; Morse, Helen; Nikolitsi, Maria; Osgathorpe, Lynne M; Potts, Simon G; Robertson, Kirsty M; Scott, Anna V; Sinclair, Frazer; Westbury, Duncan B; Stone, Graham N
Planted meadows are increasingly used to improve the biodiversity and aesthetic amenity value of urban areas. Although many 'pollinator-friendly' seed mixes are available, the floral resources these provide to flower-visiting insects, and how these change through time, are largely unknown. Such data are necessary to compare the resources provided by alternative meadow seed mixes to each other and to other flowering habitats. We used quantitative surveys of over 2 million flowers to estimate the nectar and pollen resources offered by two exemplar commercial seed mixes (one annual, one perennial) and associated weeds grown as 300m2 meadows across four UK cities, sampled at six time points between May and September 2013. Nectar sugar and pollen rewards per flower varied widely across 65 species surveyed, with native British weed species (including dandelion, Taraxacum agg.) contributing the top five nectar producers and two of the top ten pollen producers. Seed mix species yielding the highest rewards per flower included Leontodon hispidus, Centaurea cyanus and C. nigra for nectar, and Papaver rhoeas, Eschscholzia californica and Malva moschata for pollen. Perennial meadows produced up to 20x more nectar and up to 6x more pollen than annual meadows, which in turn produced far more than amenity grassland controls. Perennial meadows produced resources earlier in the year than annual meadows, but both seed mixes delivered very low resource levels early in the year and these were provided almost entirely by native weeds. Pollen volume per flower is well predicted statistically by floral morphology, and nectar sugar mass and pollen volume per unit area are correlated with flower counts, raising the possibility that resource levels can be estimated for species or habitats where they cannot be measured directly. Our approach does not incorporate resource quality information (for example, pollen protein or essential amino acid content), but can easily do so when suitable data
Damien M Hicks
Full Text Available Planted meadows are increasingly used to improve the biodiversity and aesthetic amenity value of urban areas. Although many 'pollinator-friendly' seed mixes are available, the floral resources these provide to flower-visiting insects, and how these change through time, are largely unknown. Such data are necessary to compare the resources provided by alternative meadow seed mixes to each other and to other flowering habitats. We used quantitative surveys of over 2 million flowers to estimate the nectar and pollen resources offered by two exemplar commercial seed mixes (one annual, one perennial and associated weeds grown as 300m2 meadows across four UK cities, sampled at six time points between May and September 2013. Nectar sugar and pollen rewards per flower varied widely across 65 species surveyed, with native British weed species (including dandelion, Taraxacum agg. contributing the top five nectar producers and two of the top ten pollen producers. Seed mix species yielding the highest rewards per flower included Leontodon hispidus, Centaurea cyanus and C. nigra for nectar, and Papaver rhoeas, Eschscholzia californica and Malva moschata for pollen. Perennial meadows produced up to 20x more nectar and up to 6x more pollen than annual meadows, which in turn produced far more than amenity grassland controls. Perennial meadows produced resources earlier in the year than annual meadows, but both seed mixes delivered very low resource levels early in the year and these were provided almost entirely by native weeds. Pollen volume per flower is well predicted statistically by floral morphology, and nectar sugar mass and pollen volume per unit area are correlated with flower counts, raising the possibility that resource levels can be estimated for species or habitats where they cannot be measured directly. Our approach does not incorporate resource quality information (for example, pollen protein or essential amino acid content, but can easily do so
Full Text Available Planning the artificial pollination of agricultural crops requires knowledge of the floral biology and reproductive system of the crop in question. Many studies have shown that rapeseed (Brassica napus Linnaeus is self-compatible and self-pollinated, but its productivity may be increased by insect visitation. In the present study, the floral biology and the response of productivity to insect visitation of two rapeseed cultivars (Hyola 420 and Hyola 61 were analyzed and compared in three regions of Rio Grande do Sul, Brazil. The rapeseed flowers presented three stages during anthesis, with the time periods varying between the cultivars. Both cultivars are self-compatible, but free visitation of insects increased productivity by 17% in the Hyola 420 cultivar and by approximately 30% in the Hyola 61 cultivar. Therefore, it is concluded that the cultivar Hyola 61 is more dependent on insect pollination than Hyola 420.
Neal D. Teaster
Full Text Available N-Acylethanolamines (NAEs are bioactive lipids derived from the hydrolysis of the membrane phospholipid N-acylphosphatidylethanolamine (NAPE. In animal systems this reaction is part of the endocannabinoid signaling pathway, which regulates a variety of physiological processes. The signaling function of NAE is terminated by fatty acid amide hydrolase (FAAH, which hydrolyzes NAE to ethanolamine and free fatty acid. Our previous work in Arabidopsis thaliana showed that overexpression of AtFAAH (At5g64440 lowered endogenous levels of NAEs in seeds, consistent with its role in NAE signal termination. Reduced NAE levels were accompanied by an accelerated growth phenotype, increased sensitivity to abscisic acid (ABA, enhanced susceptibility to bacterial pathogens, and early flowering. Here we investigated the nature of the early flowering phenotype of AtFAAH overexpression. AtFAAH overexpressors flowered several days earlier than wild type and AtFAAH knockouts under both non-inductive short day (SD and inductive long day (LD conditions. Microarray analysis revealed that the FLOWERING LOCUS T (FT gene, which plays a major role in regulating flowering time, and one target MADS box transcription factor, SEPATALLA3 (SEP3, were elevated in AtFAAH overexpressors. Furthermore, AtFAAH overexpressors, with the early flowering phenotype had lower endogenous NAE levels in leaves compared to wild type prior to flowering. Exogenous application of NAE 12:0, which was reduced by up to 30% in AtFAAH overexpressors, delayed the onset of flowering in wild type plants. We conclude that the early flowering phenotype of AtFAAH overexpressors is, in part, explained by elevated FT gene expression resulting from the enhanced NAE hydrolase activity of AtFAAH, suggesting that NAE metabolism may participate in floral signaling pathways.
Amy Marie Iler
Full Text Available Interactions between invasive and native plants for pollinators vary from competition to facilitation of pollination of native plants. Theory predicts that relative floral densities should account for some of this variation in outcomes, with facilitation at low floral densities and competition at high floral densities of the invader. We tested this prediction by quantifying pollination and female reproductive success of a native herb, Geranium maculatum, in three experimental arrays that varied in floral density of the invasive shrub Lonicera maackii: control (no L. maackii, low floral density of L. maackii, and high floral density of L. maackii. A low density of L. maackii flowers was associated with an increase in pollinator visitation rate to G. maculatum flowers and an increase in conspecific pollen deposition compared to controls and high density arrays. Increased visitation rates were not associated with an increase in the number of visitors to low density arrays, suggesting instead that a behavioural switch in visitation within the array accounted for increased pollen deposition. In contrast, the only evidence of competition in high density arrays was a shorter duration of visits to G. maculatum flowers relative to the other treatments. The number of seeds per flower did not vary among treatments, although trends in seeds per flower were consistent with patterns of pollinator foraging behaviour. Given increased pollinator visits and pollen deposition at a low density of the invader, our study indicates that complete eradication of invasives as a management or restoration technique may have unintended negative consequences for pollination of native plants.
Full Text Available Floral transition from the vegetative to the reproductive growth phase is a major change in the plant life cycle and a key factor in reproductive success. In rice (Oryza sativa L., a facultative short-day plant, numerous flowering time and flower formation genes that control floral transition have been identified and their physiological effects and biochemical functions have been clarified. In the present study, we used a Se14-deficient mutant line (HS112 and other flowering mutant lines to investigate the photoperiodic response, chromosomal location and function in the photoperiod sensitivity of the Se14 gene. We also studied the interactive effects of this locus with other crucial flowering time genes. We found that Se14 is independent of the known photoperiod-sensitive genes, such as Hd1 and Ghd7, and is identical to Os03g0151300, which encodes a Jumonji C (JmjC domain-containing protein. Expression analysis revealed that the expressions of RFT1, a floral initiator known as a "florigen-like gene", and Ehd1 were up-regulated in HS112, whereas this up-regulation was not observed in the original variety of 'Gimbozu'. ChIP assays of the methylation states of histone H3 at lysine 4 (H3K4 revealed that the trimethylated H3K4 in the promoter region of the RFT1 chromatin was significantly increased in HS112. We conclude that Se14 is a novel photoperiod-sensitivity gene that has a suppressive effect on floral transition (flowering time under long day-length conditions through the modification of chromatin structure by H3K4me3 demethylation in the promoter region of RFT1.
Evgenia V. Kupriyanova
Full Text Available DNA topoisomerase I alpha (TOP1α plays a specific role in Arabidopsis thaliana development and is required for stem cell regulation in shoot and floral meristems. Recently, a new role independent of meristem functioning has been described for TOP1α, namely flowering time regulation. The same feature had been detected by us earlier for fas5, a mutant allele of TOP1α. In this study we clarify the effects of fas5 on bolting initiation and analyze the molecular basis of its role on flowering time regulation. We show that fas5 mutation leads to a constitutive shade avoidance syndrome, accompanied by leaf hyponasty, petiole elongation, lighter leaf color and early bolting. Other alleles of TOP1α demonstrate the same shade avoidance response. RNA sequencing confirmed the activation of shade avoidance gene pathways in fas5 mutant plants. It also revealed the repression of many genes controlling floral meristem identity and organ morphogenesis. Our research further expands the knowledge of TOP1α function in plant development and reveals that besides stem cell maintenance TOP1α plays an important new role in regulating the adaptive plant response to light stimulus and flower development.
Shi-Guo SUN; Chi-Yuan YAO
Flower orientation has been considered one aspect of floral attraction.Plants growing on slopes should orientate their flowers facing down slope towards greater open space to enhance reproduction by attracting more pollinators.Flower angle and floral symmetry may affect this pattern; for example,this trend would be overshadowed in vertical/pendent flowers with radial symmetry because the flowers can attract pollinators and provide landing platforms from many directions.We investigated this hypothesis in Lilium duchartrei,a herb with pendent and actinomorphic flowers,in the Hengduan Mountains region of China by measuring flower direction for individuals growing on fiat ground and on slopes.We also changed flower direction from facing down to up slope to test the effects on pollinator visitation frequency and subsequent plant reproduction.Plants growing on flat ground orientate their flowers equally towards the four geomagnetic directions,whereas the flowers on individuals growing on slopes preferentially face down slope.This pattern was more pronounced for individuals growing on steeper slopes.There was a positive correlation between slope angle and the seed set of flowers facing down slope (control),but a negative correlation between seed set and flowers facing up slope.The visitation frequency also tended to be higher for control flowers on steeper slopes and lower for those flowers changed to face up slope.Unexpectedly,floral direction was not affected by flower angle or floral symmetry.The results suggest that a down slope orientation of flowers could function to improve pollination in heterogeneous pollination environments.
Welsford, Megan R; Hobbhahn, Nina; Midgley, Jeremy J; Johnson, Steven D
Transitions between animal and wind pollination have occurred in many lineages and have been linked to various floral modifications, but these have seldom been assessed in a phylogenetic framework. In the dioecious genus Leucadendron (Proteaceae), transitions from insect to wind pollination have occurred at least four times. Using analyses that controlled for relatedness among Leucadendron species, we investigated how these transitions shaped the evolution of floral structural and signaling traits, including the degree of sexual dimorphism in these traits. Pollen grains of wind-pollinated species were found to be smaller, more numerous, and dispersed more efficiently in wind than were those of insect-pollinated species. Wind-pollinated species also exhibited a reduction in spectral contrast between showy subtending leaves and background foliage, reduced volatile emissions, and a greater degree of sexual dimorphism in color and scent. Uniovulate flowers and inflorescence condensation are conserved ancestral features in Leucadendron and likely served as exaptations in shifts to wind pollination. These results offer insights into the key modifications of male and female floral traits involved in transitions between insect and wind pollination.
Lazakis, Chloë M; Coneva, Viktoriya; Colasanti, Joseph
Higher plants use multiple perceptive measures to coordinate flowering time with environmental and endogenous cues. Physiological studies show that florigen is a mobile factor that transmits floral inductive signals from the leaf to the shoot apex. Arabidopsis FT protein is widely regarded as the archetype florigen found in diverse plant species, particularly in plants that use inductive photoperiods to flower. Recently, a large family of FT homologues in maize, the Zea CENTRORADIALIS (ZCN) genes, was described, suggesting that maize also contains FT-related proteins that act as a florigen. The product of one member of this large family, ZCN8, has several attributes that make it a good candidate as a maize florigen. Mechanisms underlying the floral transition in maize are less well understood than those of other species, partly because flowering in temperate maize is dependent largely on endogenous signals. The maize indeterminate1 (id1) gene is an important regulator of maize autonomous flowering that acts in leaves to mediate the transmission or production of florigenic signals. This study finds that id1 acts upstream of ZCN8 to control its expression, suggesting a possible new link to flowering in day-neutral maize. Moreover, in teosinte, a tropical progenitor of maize that requires short-day photoperiods to induce flowering, ZCN8 is highly up-regulated in leaves under inductive photoperiods. Finally, vascular-specific expression of ZCN8 in Arabidopsis complements the ft-1 mutation, demonstrating that leaf-specific expression of ZCN8 can induce flowering. These results suggest that ZCN8 may encode a florigen that integrates both endogenous and environmental signals in maize.
Samuel J Anthony; Willow Zuchowski; William N Setzer
The floral essential oils of Brugmansia suaveolens, from Monteverde , Costa Rica , were collected at three different times of the day by hydrodistillation and the oils analyzed by gas chromatography-mass spectrometry (GC-MS...