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Jo Ann Banks - One of the best experts on this subject based on the ideXlab platform.
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sex determination in ceratopteris richardii is accompanied by transcriptome changes that drive epigenetic reprogramming of the young Gametophyte
G3: Genes Genomes Genetics, 2018Co-Authors: Nadia M Atallah, Olga Vitek, Federico Gaiti, Milos Tanurdzic, Jo Ann BanksAbstract:The fern Ceratopteris richardii is an important model for studies of sex determination and gamete differentiation in homosporous plants. Here we use RNA-seq to de novo assemble a transcriptome and identify genes differentially expressed in young Gametophytes as their sex is determined by the presence or absence of the male-inducing pheromone called antheridiogen. Of the 1,163 consensus differentially expressed genes identified, the vast majority (1,030) are up-regulated in Gametophytes treated with antheridiogen. GO term enrichment analyses of these DEGs reveals that a large number of genes involved in epigenetic reprogramming of the Gametophyte genome are up-regulated by the pheromone. Additional hormone response and development genes are also up-regulated by the pheromone. This C. richardii Gametophyte transcriptome and gene expression dataset will prove useful for studies focusing on sex determination and differentiation in plants.
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arsenic hyperaccumulation in Gametophytes of pteris vittata a new model system for analysis of arsenic hyperaccumulation
Plant Physiology, 2004Co-Authors: Luke Gumaelius, Brett Lahner, David E Salt, Jo Ann BanksAbstract:The sporophyte of the fern Pteris vittata is known to hyperaccumulate arsenic (As) in its fronds to .1% of its dry weight. Hyperaccumulation of As by plants has been identified as a valuable trait for the development of a practical phytoremediation processes for removal of this potentially toxic trace element from the environment. However, because the sporophyte of P. vittata is a slow growing perennial plant, with a large genome and no developed genetics tools, it is not ideal for investigations into the basic mechanisms underlying As hyperaccumulation in plants. However, like other homosporous ferns, P. vittata produces and releases abundant haploid spores from the parent sporophyte plant which upon germination develop as free-living, autotrophic haploid Gametophyte consisting of a small (,1 mm) single-layered sheet of cells. Its small size, rapid growth rate, ease of culture, and haploid genome make the Gametophyte a potentially ideal system for the application of both forward and reverse genetics for the study of As hyperaccumulation. Here we report that Gametophytes of P. vittata hyperaccumulate As in a similar manner to that previously observed in the sporophyte. Gametophytes are able to grow normally in medium containing 20 mM arsenate and accumulate .2.5% of their dry weight as As. This contrasts with Gametophytes of the related nonaccumulating fern Ceratopteris richardii, which die at even low (0.1 mM) As concentrations. Interestingly, Gametophytes of the related As accumulator Pityrogramma calomelanos appear to tolerate and accumulate As to intermediate levels compared to P. vittata and C. richardii. Analysis of Gametophyte populations from 40 different P. vittata sporophyte plants collected at different sites in Florida also revealed the existence of natural variability in As tolerance but not accumulation. Such observations should open the door to the application of new and powerful genetic tools for the dissection of the molecular mechanisms involved in As hyperaccumulation in P. vittata using Gametophytes as an easily manipulated model system.
Stephen S Mulkey - One of the best experts on this subject based on the ideXlab platform.
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ecological and evolutionary consequences of desiccation tolerance in tropical fern Gametophytes
New Phytologist, 2007Co-Authors: James E Watkins, Michelle C Mack, Thomas R Sinclair, Stephen S MulkeyAbstract:Summary • Ferns have radiated into the same diverse environments as spermatophytes, and have done so with an independent Gametophyte that is not protected by the parent plant. The degree and extent of desiccation tolerance (DT) in the Gametophytes of tropical fern species was assessed to understand mechanisms that have allowed ferns to radiate into a diversity of habitats. • Species from several functional groups were subjected to a series of desiccation events, including varying degrees of intensity and multiple desiccation cycles. Measurements of chlorophyll fluorescence were used to assess recovery ability and compared with species ecology and Gametophyte morphology. • It is shown that vegetative DT (rare in vascular plants) is widely exhibited in fern Gametophytes and the degree of tolerance is linked to species habitat preference. It is proposed that Gametophyte morphology influences water-holding capacity, a novel mechanism that may help to explain how ferns have radiated into drought-prone habitats. • Fern Gametophytes have often been portrayed as extreme mesophytes with little tolerance for desiccation. The discovery of DT in Gametophytes holds potential for improving our understanding of both the controls on fern species distribution and their evolution. It also advances a new system with which to study the evolution of DT in vascular plants.
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Gametophyte ecology and demography of epiphytic and terrestrial tropical ferns
American Journal of Botany, 2007Co-Authors: James E Watkins, Michelle K Mack, Stephen S MulkeyAbstract:Factors that influence the distribution of ferns are poorly understood and likely reflect the ecology of both the sporophyte and the Gametophyte generation. Little study has been done on the ecology of the Gametophyte generation, especially in regard to tropical species. The goal of this study was to examine demography and the influence of light and disturbance on the distribution of the Gametophytes of several tropical epiphytic, hemiepiphytic, and terrestrial fern species. Through a series of observational and experimental studies, we found that increased terrestrial Gametophyte density and richness were related to both increased light and disturbance. By contrast, increased light had no influence, and increased disturbance negatively affected epiphytic density. Over a 25-mo demographic study, epiphytic and hemiepiphytic species had significantly greater longevities and lower recruitment rates than terrestrial species. Such unique strategies may have evolved in response to different disturbance regimens between the two habitats. Terrestrial species encounter and are adapted to more frequent disturbance and have invested in rapid Gametophyte growth and recruitment. Epiphytic species may be more influenced by bryophyte competition, and in habitats of relatively low disturbance, they have invested in greater size and longevities. In such systems, Gametophytes are able to survive for years waiting for favorable recruitment conditions. Though the study of ferns has been fundamental to our understanding of vascular plant biology, even the most basic aspects of fern ecology have only begun to be examined. Because ferns have both independent Gametophytes and sporophytes, ferns can reveal important aspects of the ecology of organisms with two free-living and fundamentally different generations. With the retention of the independent Gametophyte, ferns also hold tremendous potential to teach us about the evolutionary ecology of early vascular plants. The paucity of ecological information on the ferns is surprising given that they play important roles at the ecosystem level in both temperate and tropical forests. For example, ferns have been shown to control the regeneration potential of forests throughout the world (George and Bazzaz, 1999; Coomes et al., 2005). In tropical forests, basket-forming ferns can harbor more arthropod diversity in a single individual than occurs in the entire canopy of the fern’s host tree (Ellwood and Foster, 2004). Ferns can also be critical players in ecosystem establishment (Russell and Vitousek, 1997). While we have some knowledge of the role of ferns in forests, our knowledge of the organismal ecology of ferns is phenomenally limited. This is especially true of the Gametophyte generation where
James E Watkins - One of the best experts on this subject based on the ideXlab platform.
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A new protocol for psychrometric pressure–volume curves of fern Gametophytes
Wiley, 2019Co-Authors: Christopher P. Krieg, James E Watkins, Katherine A. MccullohAbstract:Premise Pressure–volume curves are a widely used analytical framework to derive several key physiological traits related to plant–water relations, including a species’ turgor loss point, osmotic potential at full turgor, and the elasticity of cell walls. We developed a novel protocol, including the preparation and treatment of fern Gametophytes, to generate data for pressure–volume curve analyses using thermocouple psychrometry. Methods and Results Gametophytes of the fern species Polystichum lemmonii were grown from spore, harvested, and subjected to a series of drying intervals. We constructed pressure–volume curves using thermocouple psychrometers to calculate Gametophyte water potential and a balance to measure relative water loss. Conclusions We present the first protocol for fern Gametophyte pressure–volume curves that can accurately determine key physiological traits in fern Gametophytes such as the turgor loss point and osmotic potential at full turgor
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ecological and evolutionary consequences of desiccation tolerance in tropical fern Gametophytes
New Phytologist, 2007Co-Authors: James E Watkins, Michelle C Mack, Thomas R Sinclair, Stephen S MulkeyAbstract:Summary • Ferns have radiated into the same diverse environments as spermatophytes, and have done so with an independent Gametophyte that is not protected by the parent plant. The degree and extent of desiccation tolerance (DT) in the Gametophytes of tropical fern species was assessed to understand mechanisms that have allowed ferns to radiate into a diversity of habitats. • Species from several functional groups were subjected to a series of desiccation events, including varying degrees of intensity and multiple desiccation cycles. Measurements of chlorophyll fluorescence were used to assess recovery ability and compared with species ecology and Gametophyte morphology. • It is shown that vegetative DT (rare in vascular plants) is widely exhibited in fern Gametophytes and the degree of tolerance is linked to species habitat preference. It is proposed that Gametophyte morphology influences water-holding capacity, a novel mechanism that may help to explain how ferns have radiated into drought-prone habitats. • Fern Gametophytes have often been portrayed as extreme mesophytes with little tolerance for desiccation. The discovery of DT in Gametophytes holds potential for improving our understanding of both the controls on fern species distribution and their evolution. It also advances a new system with which to study the evolution of DT in vascular plants.
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Gametophyte ecology and demography of epiphytic and terrestrial tropical ferns
American Journal of Botany, 2007Co-Authors: James E Watkins, Michelle K Mack, Stephen S MulkeyAbstract:Factors that influence the distribution of ferns are poorly understood and likely reflect the ecology of both the sporophyte and the Gametophyte generation. Little study has been done on the ecology of the Gametophyte generation, especially in regard to tropical species. The goal of this study was to examine demography and the influence of light and disturbance on the distribution of the Gametophytes of several tropical epiphytic, hemiepiphytic, and terrestrial fern species. Through a series of observational and experimental studies, we found that increased terrestrial Gametophyte density and richness were related to both increased light and disturbance. By contrast, increased light had no influence, and increased disturbance negatively affected epiphytic density. Over a 25-mo demographic study, epiphytic and hemiepiphytic species had significantly greater longevities and lower recruitment rates than terrestrial species. Such unique strategies may have evolved in response to different disturbance regimens between the two habitats. Terrestrial species encounter and are adapted to more frequent disturbance and have invested in rapid Gametophyte growth and recruitment. Epiphytic species may be more influenced by bryophyte competition, and in habitats of relatively low disturbance, they have invested in greater size and longevities. In such systems, Gametophytes are able to survive for years waiting for favorable recruitment conditions. Though the study of ferns has been fundamental to our understanding of vascular plant biology, even the most basic aspects of fern ecology have only begun to be examined. Because ferns have both independent Gametophytes and sporophytes, ferns can reveal important aspects of the ecology of organisms with two free-living and fundamentally different generations. With the retention of the independent Gametophyte, ferns also hold tremendous potential to teach us about the evolutionary ecology of early vascular plants. The paucity of ecological information on the ferns is surprising given that they play important roles at the ecosystem level in both temperate and tropical forests. For example, ferns have been shown to control the regeneration potential of forests throughout the world (George and Bazzaz, 1999; Coomes et al., 2005). In tropical forests, basket-forming ferns can harbor more arthropod diversity in a single individual than occurs in the entire canopy of the fern’s host tree (Ellwood and Foster, 2004). Ferns can also be critical players in ecosystem establishment (Russell and Vitousek, 1997). While we have some knowledge of the role of ferns in forests, our knowledge of the organismal ecology of ferns is phenomenally limited. This is especially true of the Gametophyte generation where
Tetsuya Higashiyama - One of the best experts on this subject based on the ideXlab platform.
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live imaging and laser disruption reveal the dynamics and cell cell communication during torenia fournieri female Gametophyte development
Plant and Cell Physiology, 2015Co-Authors: Daichi Susaki, Hidenori Takeuchi, Hiroki Tsutsui, Daisuke Kurihara, Tetsuya HigashiyamaAbstract:: The female Gametophytes of many flowering plants contain one egg cell, one central cell, two synergid cells and three antipodal cells with respective morphological characteristics and functions. These cells are formed by cellularization of a multinuclear female Gametophyte. However, the dynamics and mechanisms of female Gametophyte development remain largely unknown due to the lack of a system to visualize directly and manipulate female Gametophytes in living material. Here, we established an in vitro ovule culture system to examine female Gametophyte development in Torenia fournieri, a unique plant species with a protruding female Gametophyte. The four-nucleate female Gametophyte became eight nucleate by the final (third) mitosis and successively cellularized and matured to attract a pollen tube. The duration of final mitosis was 28 ± 6.5 min, and cellularization was completed in 54 ± 20 min after the end of the third mitosis. Fusion of polar nuclei in the central cell occurred in 13.1 ± 1.1 h, and onset of expression of LURE2, a pollen tube attractant gene, was visualized by a green fluorescent protein reporter 10.7 ± 2.3 h after cellularization. Laser disruption analysis demonstrated that the egg and central cells were required for synergid cells to acquire the pollen tube attraction function. Moreover, aberrant nuclear positioning and down-regulation of LURE2 were observed in one of the two synergid cells after disrupting an immature egg cell, suggesting that cell specification was affected. Our system provides insights into the precise dynamics and mechanisms of female Gametophyte development in T. fournieri.
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Live Imaging and Laser Disruption Reveal the Dynamics and Cell–Cell Communication During Torenia fournieri Female Gametophyte Development
Plant and Cell Physiology, 2015Co-Authors: Daichi Susaki, Hidenori Takeuchi, Hiroki Tsutsui, Daisuke Kurihara, Tetsuya HigashiyamaAbstract:The female Gametophytes of many flowering plants contain one egg cell, one central cell, two synergid cells and three antipodal cells with respective morphological characteristics and functions. These cells are formed by cellularization of a multinuclear female Gametophyte. However, the dynamics and mechanisms of female Gametophyte development remain largely unknown due to the lack of a system to visualize directly and manipulate female Gametophytes in living material. Here, we established an in vitro ovule culture system to examine female Gametophyte development in Torenia fournieri, a unique plant species with a protruding female Gametophyte. The four-nucleate female Gametophyte became eight nucleate by the final (third) mitosis and successively cellularized and matured to attract a pollen tube. The duration of final mitosis was 28± 6.5 min, and cellularization was completed in 54± 20 min after the end of the third mitosis. Fusion of polar nuclei in the central cell occurred in 13.1± 1.1 h, and onset of expression of LURE2, a pollen tube attractant gene, was visualized by a green fluorescent protein reporter 10.7± 2.3 h after cellularization. Laser disruption analysis demonstrated that the egg and central cells were required for synergid cells to acquire the pollen tube attraction function. Moreover, aberrant nuclear positioning and down-regulation of LURE2 were observed in one of the two synergid cells after disrupting an immature egg cell, suggesting that cell specification was affected. Our system provides insights into the precise dynamics and mechanisms of female Gametophyte development in T. fournieri.
Wei-cai Yang - One of the best experts on this subject based on the ideXlab platform.
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slow walker2 a noc1 mak21 homologue is essential for coordinated cell cycle progression during female Gametophyte development in arabidopsis
Plant Physiology, 2009Co-Authors: Li Yuan, Zuoshun Tang, Venkatesan Sundaresan, Naiyou Liu, Dongqiao Shi, Jie Liu, Wei-cai YangAbstract:Morphogenesis requires the coordination of cell growth, division, and cell differentiation. Female gametogenesis in flowering plants, where a single haploid spore undergoes continuous growth and nuclear division without cytokinesis to form an eight-nucleate coenocytic embryo sac before cellularization, provides a good system to study the genetic control of such processes in multicellular organisms. Here, we report the characterization of an Arabidopsis (Arabidopsis thaliana) female Gametophyte mutant, slow walker2 (swa2), in which the progression of the mitotic cycles and the synchrony of female Gametophyte development were impaired, causing an arrest of female Gametophytes at the two-, four-, or eight-nucleate stage. Delayed pollination test showed that a portion of the mutant ovules were able to develop into functional embryo sacs and could be fertilized. SWA2 encodes a nucleolar protein homologous to yeast NUCLEOLAR COMPLEX ASSOCIATED PROTEIN1 (NOC1)/MAINTENANCE OF KILLER21 that, together with NOC2, is involved in preribosome export from the nucleus to the cytoplasm. Similarly, SWA2 can physically interact with a putative Arabidopsis NOC2 homologue. SWA2 is expressed ubiquitously throughout the plant, at high levels in actively dividing tissues and Gametophytes. Therefore, we conclude that SWA2 most likely plays a role in ribosome biogenesis that is essential for the coordinated mitotic progression of the female Gametophyte.
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SLOW WALKER2, a NOC1/MAK21 Homologue, Is Essential for Coordinated Cell Cycle Progression during Female Gametophyte Development in Arabidopsis
Plant Physiology, 2009Co-Authors: Na Li, Xin-ran Li, Zuoshun Tang, Venkatesan Sundaresan, Li Yuan, Wei-cai YangAbstract:Morphogenesis requires the coordination of cell growth, division, and cell differentiation. Female gametogenesis in flowering plants, where a single haploid spore undergoes continuous growth and nuclear division without cytokinesis to form an eight-nucleate coenocytic embryo sac before cellularization, provides a good system to study the genetic control of such processes in multicellular organisms. Here, we report the characterization of an Arabidopsis (Arabidopsis thaliana) female Gametophyte mutant, slow walker2 (swa2), in which the progression of the mitotic cycles and the synchrony of female Gametophyte development were impaired, causing an arrest of female Gametophytes at the two-, four-, or eight-nucleate stage. Delayed pollination test showed that a portion of the mutant ovules were able to develop into functional embryo sacs and could be fertilized. SWA2 encodes a nucleolar protein homologous to yeast NUCLEOLAR COMPLEX ASSOCIATED PROTEIN1 (NOC1)/MAINTENANCE OF KILLER21 that, together with NOC2, is involved in preribosome export from the nucleus to the cytoplasm. Similarly, SWA2 can physically interact with a putative Arabidopsis NOC2 homologue. SWA2 is expressed ubiquitously throughout the plant, at high levels in actively dividing tissues and Gametophytes. Therefore, we conclude that SWA2 most likely plays a role in ribosome biogenesis that is essential for the coordinated mitotic progression of the female Gametophyte.
