The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Candace H Haigler - One of the best experts on this subject based on the ideXlab platform.
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cultures of gossypium barbadense Cotton ovules offer insights into the microtubule mediated control of Fiber cell expansion
Planta, 2019Co-Authors: Ethan T Pierce, Benjamin P Graham, Michael R Stiff, Jason A Osborne, Candace H HaiglerAbstract:A novel method for culturing ovules of Gossypium barbadense allowed in vitro comparisons with Gossypium hirsutum and revealed variable roles of microtubules in controlling Cotton Fiber cell expansion. Cotton Fibers undergo extensive elongation and secondary wall thickening as they develop into our most important renewable textile material. These single cells elongate at the apex as well as elongating and expanding in diameter behind the apex. These multiple growth modes represent an interesting difference compared to classical tip-growing cells that needs to be explored further. In vitro ovule culture enables experimental analysis of the controls of Cotton Fiber development in commonly grown Gossypium hirsutum Cotton, but, previously, there was no equivalent system for G. barbadense, which produces higher quality Cotton Fiber. Here, we describe: (a) how to culture the ovules of G. barbadense successfully, and (b) the results of an in vitro experiment comparing the role of microtubules in controlling cell expansion in different zones near the apex of three types of Cotton Fiber tips. Adding the common herbicide fluridone, 1-Methyl-3-phenyl-5-[3-(trifluoromethyl)phenyl]-4(1H)-pyridinone, to the medium supported G. barbadense ovule culture, with positive impacts on the number of useful ovules and Fiber length. The effect is potentially mediated through inhibited synthesis of abscisic acid, which antagonized the positive effects of fluridone. Fiber development was perturbed by adding colchicine, a microtubule antagonist, to ovules of G. barbadense and G. hirsutum cultured 2 days after flowering. The results supported the zonal control of cell expansion in one type of G. hirsutum Fiber tip and highlighted differences in the role of microtubules in modulating cell expansion between three types of Cotton Fiber tips.
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metabolomic and transcriptomic insights into how Cotton Fiber transitions to secondary wall synthesis represses lignification and prolongs elongation
BMC Genomics, 2015Co-Authors: John R Tuttle, Gyoungju Nah, Mary V Duke, Danny C Alexander, Xueying Guan, Qingxin Song, Jeffrey Z Chen, Brian E Scheffler, Candace H HaiglerAbstract:The morphogenesis of single-celled Cotton Fiber includes extreme elongation and staged cell wall differentiation. Designing strategies for improving Cotton Fiber for textiles and other uses relies on uncovering the related regulatory mechanisms. In this research we compared the transcriptomes and metabolomes of two Gossypium genotypes, Gossypium barbadense cv Phytogen 800 and G. hirsutum cv Deltapine 90. When grown in parallel, the two types of Fiber developed similarly except for prolonged Fiber elongation in the G. barbadense cultivar. The data were collected from isolated Fibers between 10 to 28 days post anthesis (DPA) representing: primary wall synthesis to support elongation; transitional cell wall remodeling; and secondary wall cellulose synthesis, which was accompanied by continuing elongation only in G. barbadense Fiber. Of 206 identified Fiber metabolites, 205 were held in common between the two genotypes. Approximately 38,000 transcripts were expressed in the Fiber of each genotype, and these were mapped to the reference set and interpreted by homology to known genes. The developmental changes in the transcriptomes and the metabolomes were compared within and across genotypes with several novel implications. Transitional cell wall remodeling is a distinct stable developmental stage lasting at least four days (18 to 21 DPA). Expression of selected cell wall related transcripts was similar between genotypes, but cellulose synthase gene expression patterns were more complex than expected. Lignification was transcriptionally repressed in both genotypes. Oxidative stress was lower in the Fiber of G. barbadense cv Phytogen 800 as compared to G. hirsutum cv Deltapine 90. Correspondingly, the G. barbadense cultivar had enhanced capacity for management of reactive oxygen species during its prolonged elongation period, as indicated by a 138-fold increase in ascorbate concentration at 28 DPA. The parallel data on deep-sequencing transcriptomics and non-targeted metabolomics for two genotypes of single-celled Cotton Fiber showed that a discrete developmental stage of transitional cell wall remodeling occurs before secondary wall cellulose synthesis begins. The data showed how lignification can be transcriptionally repressed during secondary cell wall synthesis, and they implicated enhanced capacity to manage reactive oxygen species through the ascorbate-glutathione cycle as a positive contributor to Fiber length.
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changes in the cell wall and cellulose content of developing Cotton Fibers investigated by ftir spectroscopy
Carbohydrate Polymers, 2014Co-Authors: Noureddine Abidi, Luis Cabrales, Candace H HaiglerAbstract:Abstract Fourier transform infrared (FTIR) spectra of Cotton Fibers harvested at different stages of development were acquired using Universal Attenuated Total Reflectance FTIR (UATR-FTIR). The main goal of the study was to monitor cell wall changes occurring during different phases of Cotton Fiber development. Two cultivars of Gossypium hirsutum L. were planted in a greenhouse (Texas Marker-1 and TX55). On the day of flowering, individual flowers were tagged and bolls were harvested. From Fibers harvested on numerous days between 10 and 56 dpa, the FTIR spectra were acquired using UATR (ZnSe-Diamond crystal) with no special sample preparation. The changes in the FTIR spectra were used to document the timing of the transition between primary and secondary cell wall synthesis. Changes in cellulose during Cotton Fiber growth and development were identified through changes in numerous vibrations within the spectra. The intensity of the vibration bands at 667 and 897 cm −1 correlated with percentage of cellulose analyzed chemically.
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Cotton Fiber cell walls of gossypium hirsutum and gossypium barbadense have differences related to loosely bound xyloglucan
PLOS ONE, 2013Co-Authors: Utku Avci, Bir Singh, Sivakumar Pattathil, Virginia Brown, Michael G Hahn, Candace H HaiglerAbstract:Cotton Fiber is an important natural textile Fiber due to its exceptional length and thickness. These properties arise largely through primary and secondary cell wall synthesis. The Cotton Fiber of commerce is a cellulosic secondary wall surrounded by a thin cuticulated primary wall, but there were only sparse details available about the polysaccharides in the Fiber cell wall of any Cotton species. In addition, Gossypium hirsutum (Gh) Fiber was known to have an adhesive Cotton Fiber middle lamella (CFML) that joins adjacent Fibers into tissue-like bundles, but it was unknown whether a CFML existed in other commercially important Cotton Fibers. We compared the cell wall chemistry over the time course of Fiber development in Gh and Gossypium barbadense (Gb), the two most important commercial Cotton species, when plants were grown in parallel in a highly controlled greenhouse. Under these growing conditions, the rate of early Fiber elongation and the time of onset of secondary wall deposition were similar in Fibers of the two species, but as expected the Gb Fiber had a prolonged elongation period and developed higher quality compared to Gh Fiber. The Gb Fibers had a CFML, but it was not directly required for Fiber elongation because Gb Fiber continued to elongate rapidly after CFML hydrolysis. For both species, Fiber at seven ages was extracted with four increasingly strong solvents, followed by analysis of cell wall matrix polysaccharide epitopes using antibody-based Glycome Profiling. Together with immunohistochemistry of Fiber cross-sections, the data show that the CFML of Gb Fiber contained lower levels of xyloglucan compared to Gh Fiber. Xyloglucan endo-hydrolase activity was also higher in Gb Fiber. In general, the data provide a rich picture of the similarities and differences in the cell wall structure of the two most important commercial Cotton species.
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Cotton Fiber a powerful single cell model for cell wall and cellulose research
Frontiers in Plant Science, 2012Co-Authors: Candace H Haigler, Lissete Betancur, Michael R Stiff, John R TuttleAbstract:Cotton Fibers are single-celled extensions of the seed epidermis. They can be isolated in pure form as they undergo staged differentiation including primary cell wall synthesis during elongation and nearly pure cellulose synthesis during secondary wall thickening. This combination of features supports clear interpretation of data about cell walls and cellulose synthesis in the context of high throughput modern experimental technologies. Prior contributions of Cotton Fiber to building fundamental knowledge about cell walls will be summarized and the dynamic changes in cell wall polymers throughout Cotton Fiber differentiation will be described. Recent successes in using stable Cotton transformation to alter Cotton Fiber cell wall properties as well as Cotton Fiber quality will be discussed. Future prospects to perform experiments more rapidly through altering Cotton Fiber wall properties via virus induced gene silencing will be evaluated.
John R Tuttle - One of the best experts on this subject based on the ideXlab platform.
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metabolomic and transcriptomic insights into how Cotton Fiber transitions to secondary wall synthesis represses lignification and prolongs elongation
BMC Genomics, 2015Co-Authors: John R Tuttle, Gyoungju Nah, Mary V Duke, Danny C Alexander, Xueying Guan, Qingxin Song, Jeffrey Z Chen, Brian E Scheffler, Candace H HaiglerAbstract:The morphogenesis of single-celled Cotton Fiber includes extreme elongation and staged cell wall differentiation. Designing strategies for improving Cotton Fiber for textiles and other uses relies on uncovering the related regulatory mechanisms. In this research we compared the transcriptomes and metabolomes of two Gossypium genotypes, Gossypium barbadense cv Phytogen 800 and G. hirsutum cv Deltapine 90. When grown in parallel, the two types of Fiber developed similarly except for prolonged Fiber elongation in the G. barbadense cultivar. The data were collected from isolated Fibers between 10 to 28 days post anthesis (DPA) representing: primary wall synthesis to support elongation; transitional cell wall remodeling; and secondary wall cellulose synthesis, which was accompanied by continuing elongation only in G. barbadense Fiber. Of 206 identified Fiber metabolites, 205 were held in common between the two genotypes. Approximately 38,000 transcripts were expressed in the Fiber of each genotype, and these were mapped to the reference set and interpreted by homology to known genes. The developmental changes in the transcriptomes and the metabolomes were compared within and across genotypes with several novel implications. Transitional cell wall remodeling is a distinct stable developmental stage lasting at least four days (18 to 21 DPA). Expression of selected cell wall related transcripts was similar between genotypes, but cellulose synthase gene expression patterns were more complex than expected. Lignification was transcriptionally repressed in both genotypes. Oxidative stress was lower in the Fiber of G. barbadense cv Phytogen 800 as compared to G. hirsutum cv Deltapine 90. Correspondingly, the G. barbadense cultivar had enhanced capacity for management of reactive oxygen species during its prolonged elongation period, as indicated by a 138-fold increase in ascorbate concentration at 28 DPA. The parallel data on deep-sequencing transcriptomics and non-targeted metabolomics for two genotypes of single-celled Cotton Fiber showed that a discrete developmental stage of transitional cell wall remodeling occurs before secondary wall cellulose synthesis begins. The data showed how lignification can be transcriptionally repressed during secondary cell wall synthesis, and they implicated enhanced capacity to manage reactive oxygen species through the ascorbate-glutathione cycle as a positive contributor to Fiber length.
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Cotton Fiber a powerful single cell model for cell wall and cellulose research
Frontiers in Plant Science, 2012Co-Authors: Candace H Haigler, Lissete Betancur, Michael R Stiff, John R TuttleAbstract:Cotton Fibers are single-celled extensions of the seed epidermis. They can be isolated in pure form as they undergo staged differentiation including primary cell wall synthesis during elongation and nearly pure cellulose synthesis during secondary wall thickening. This combination of features supports clear interpretation of data about cell walls and cellulose synthesis in the context of high throughput modern experimental technologies. Prior contributions of Cotton Fiber to building fundamental knowledge about cell walls will be summarized and the dynamic changes in cell wall polymers throughout Cotton Fiber differentiation will be described. Recent successes in using stable Cotton transformation to alter Cotton Fiber cell wall properties as well as Cotton Fiber quality will be discussed. Future prospects to perform experiments more rapidly through altering Cotton Fiber wall properties via virus induced gene silencing will be evaluated.
Xiaoya Chen - One of the best experts on this subject based on the ideXlab platform.
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gene expression and metabolite profiles of Cotton Fiber during cell elongation and secondary cell wall synthesis
Cell Research, 2007Co-Authors: Jinying Gou, Lingjian Wang, Shuangping Chen, Xiaoya ChenAbstract:Cotton Fibers elongate rapidly after initiation of elongation, eventually leading to the deposit of a large amount of cellulose. To reveal features of Cotton Fiber cells at the fast elongation and the secondary cell wall synthesis stages, we compared the respective transcriptomes and metabolite profiles. Comparative analysis of transcriptomes by cDNA array identified 633 genes that were differentially regulated during Fiber development. Principal component analysis (PCA) using expressed genes as variables divided Fiber samples into four groups, which are diagnostic of developmental stages. Similar grouping results are also found if we use non-polar or polar metabolites as variables for PCA of developing Fibers. Auxin signaling, wall-loosening and lipid metabolism are highly active during Fiber elongation, whereas cellulose biosynthesis is predominant and many other metabolic pathways are downregulated at the secondary cell wall synthesis stage. Transcript and metabolite profiles and enzyme activities are consistent in demonstrating a specialization process of Cotton Fiber development toward cellulose synthesis. These data demonstrate that Cotton Fiber cell at a certain stage has its own unique feature, and developmental stages of Cotton Fiber cells can be distinguished by their transcript and metabolite profiles. During the secondary cell wall synthesis stage, metabolic pathways are streamed into cellulose synthesis.
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control of plant trichome development by a Cotton Fiber myb gene
The Plant Cell, 2004Co-Authors: Shui Wang, Lingjian Wang, Jiawei Wang, Bin Luo, Jinying Gou, Xiaoya ChenAbstract:Cotton (Gossypium spp) plants produce seed trichomes (Cotton Fibers) that are an important commodity worldwide; however, genes controlling Cotton Fiber development have not been characterized. In Arabidopsis thaliana the MYB gene GLABRA1 (GL1) is a central regulator of trichome development. Here, we show that promoter of a Cotton Fiber gene, RD22-like1 (RDL1), contains a homeodomain binding L1 box and a MYB binding motif that confer trichome-specific expression in Arabidopsis. A Cotton MYB protein GaMYB2/Fiber Factor 1 transactivated the RDL1 promoter both in yeast and in planta. Real-time PCR and in situ analysis showed that GaMYB2 is predominantly expressed early in developing Cotton Fibers. After transferring into Arabidopsis, GL1::GaMYB2 rescued trichome formation of a gl1 mutant, and interestingly, 35S::GaMYB2 induced seed-trichome production. We further demonstrate that the first intron of both GL1 and GaMYB2 plays a role in patterning trichomes: it acts as an enhancer in trichome and a repressor in nontrichome cells, generating a trichome-specific pattern of MYB gene expression. Disruption of a MYB motif conserved in intron 1 of GL1, WEREWOLF, and GaMYB2 genes affected trichome production. These results suggest that Cotton and Arabidopsis use similar transcription factors for regulating trichomes and that GaMYB2 may be a key regulator of Cotton Fiber development.
Robert T Furbank - One of the best experts on this subject based on the ideXlab platform.
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genotypic and developmental evidence for the role of plasmodesmatal regulation in Cotton Fiber elongation mediated by callose turnover
Plant Physiology, 2004Co-Authors: Yongling Ruan, Rosemary G White, Robert T FurbankAbstract:Cotton Fibers are single-celled hairs that elongate to several centimeters long from the seed coat epidermis of the tetraploid species (Gossypium hirsutum and Gossypium barbadense). Thus, Cotton Fiber is a unique system to study the mechanisms of rapid cell expansion. Previous work has shown a transient closure of plasmodesmata during Fiber elongation (Y.-L. Ruan, D.J. Llewellyn, R.T. Furbank [2001] Plant Cell 13: 47–60). To examine the importance of this closure in Fiber elongation, we compared the duration of the plasmodesmata closure among different Cotton genotypes differing in Fiber length. Confocal imaging of the membrane-impermeant fluorescent molecule carboxyfluorescein revealed a genotypic difference in the duration of the plasmodesmata closure that positively correlates with Fiber length among three tetraploid genotypes and two diploid progenitors. In all cases, the closure occurred at the rapid phase of elongation. Aniline blue staining and immunolocalization studies showed that callose deposition and degradation at the Fiber base correlates with the timing of plasmodesmata closure and reopening, respectively. Northern analyses showed that the expression of a Fiber-specific β-1,3-glucanase gene, GhGluc1, was undetectable when callose was deposited at the Fiber base but became evident at the time of callose degradation. Genotypically, the level of GhGluc1 expression was high in the short Fiber genotype and weak in the intermediate and long Fiber genotypes. The data provide genotypic and developmental evidence that (1) plasmodesmata closure appears to play an important role in elongating Cotton Fibers, (2) callose deposition and degradation may be involved in the plasmodesmata closure and reopening, respectively, and (3) the expression of GhGluc1 could play a role in this process by degrading callose, thus opening the plasmodesmata.
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suppression of sucrose synthase gene expression represses Cotton Fiber cell initiation elongation and seed development
The Plant Cell, 2003Co-Authors: Yongling Ruan, Danny J Llewellyn, Robert T FurbankAbstract:Cotton is the most important textile crop as a result of its long cellulose-enriched mature Fibers. These single-celled hairs initiate at anthesis from the ovule epidermis. To date, genes proven to be critical for Fiber development have not been identified. Here, we examined the role of the sucrose synthase gene (Sus) in Cotton Fiber and seed by transforming Cotton with Sus suppression constructs. We focused our analysis on 0 to 3 days after anthesis (DAA) for early Fiber development and 25 DAA, when the Fiber and seed are maximal in size. Suppression of Sus activity by 70% or more in the ovule epidermis led to a Fiberless phenotype. The Fiber initials in those ovules were fewer and shrunken or collapsed. The level of Sus suppression correlated strongly with the degree of inhibition of Fiber initiation and elongation, probably as a result of the reduction of hexoses. By 25 DAA, a portion of the seeds in the fruit showed Sus suppression only in the seed coat Fibers and transfer cells but not in the endosperm and embryo. These transgenic seeds were identical to wild-type seeds except for much reduced Fiber growth. However, the remaining seeds in the fruit showed Sus suppression both in the seed coat and in the endosperm and embryo. These seeds were shrunken with loss of the transfer cells and were <5% of wild-type seed weight. These results demonstrate that Sus plays a rate-limiting role in the initiation and elongation of the single-celled Fibers. These analyses also show that suppression of Sus only in the maternal seed tissue represses Fiber development without affecting embryo development and seed size. Additional suppression in the endosperm and embryo inhibits their own development, which blocks the formation of adjacent seed coat transfer cells and arrests seed development entirely.
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the control of single celled Cotton Fiber elongation by developmentally reversible gating of plasmodesmata and coordinated expression of sucrose and k transporters and expansin
The Plant Cell, 2001Co-Authors: Yongling Ruan, Danny J Llewellyn, Robert T FurbankAbstract:Each Cotton Fiber is a single cell that elongates to 2.5 to 3.0 cm from the seed coat epidermis within ∼16 days after anthesis (DAA). To elucidate the mechanisms controlling this rapid elongation, we studied the gating of Fiber plasmodesmata and the expression of the cell wall–loosening gene expansin and plasma membrane transporters for sucrose and K+, the major osmotic solutes imported into Fibers. Confocal imaging of the membrane-impermeant fluorescent solute carboxyfluorescein (CF) revealed that the Fiber plasmodesmata were initially permeable to CF (0 to 9 DAA), but closed at ∼10 DAA and re-opened at 16 DAA. A developmental switch from simple to branched plasmodesmata was also observed in Fibers at 10 DAA. Coincident with the transient closure of the plasmodesmata, the sucrose and K+ transporter genes were expressed maximally in Fibers at 10 DAA with sucrose transporter proteins predominately localized at the Fiber base. Consequently, Fiber osmotic and turgor potentials were elevated, driving the rapid phase of elongation. The level of expansin mRNA, however, was high at the early phase of elongation (6 to 8 DAA) and decreased rapidly afterwards. The Fiber turgor was similar to the underlying seed coat cells at 6 to 10 DAA and after 16 DAA. These results suggest that Fiber elongation is initially achieved largely by cell wall loosening and finally terminated by increased wall rigidity and loss of higher turgor. To our knowledge, this study provides an unprecedented demonstration that the gating of plasmodesmata in a given cell is developmentally reversible and is coordinated with the expression of solute transporters and the cell wall–loosening gene. This integration of plasmodesmatal gating and gene expression appears to control Fiber cell elongation.
Yongling Ruan - One of the best experts on this subject based on the ideXlab platform.
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overexpression of ghsusa1 increases plant biomass and improves Cotton Fiber yield and quality
Plant Biotechnology Journal, 2012Co-Authors: Yanjie Jiang, Yongling Ruan, Tianzhen ZhangAbstract:Summary Cotton (Gossypium spp.) is an important economic crop and the largest source of textile Fiber in the world. However, to date, only a few genes have been identified that exhibit critical roles in Fiber development, and few has shown positive effects on Fiber yield and quality in transgenic Cotton. Here, we report the characterization of a novel sucrose synthase (SusA1) gene from a superior quality Fiber germplasm line 7235 in Gossypium hirsutum. By association analysis, GhSusA1 was highly correlated with Fiber qualities in (7235× TM-1) recombinant inbred lines based on polymorphism of GhSusA1 between 7235 and TM-1. Subsequently, based on an interspecific population of 141 BC1 individuals generated from the cross between TM-1 and Gossypium barbadense line, Hai7124, we further mapped GhSusA1 genes on homeologous chromosomes A8 (chro.8) and D8 (chro.24). Suppression of GhSusA1 in transgenic Cotton reduced Fiber quality and decreased the boll size and seed weight. Importantly, overexpression of this gene increased Fiber length and strength, with the latter indicated by the enhanced thickening of cell wall during secondary wall formation stage. Moreover, increasing GhSusA1 transcript abundance in vegetative tissues led to elevated seedling biomass. Together, these findings identified GhSusA1 as a key regulator of sink strength in Cotton, which is tightly associated with productivity, and hence a promising candidate gene that can be developed to increase Cotton Fiber yield and quality.
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genotypic and developmental evidence for the role of plasmodesmatal regulation in Cotton Fiber elongation mediated by callose turnover
Plant Physiology, 2004Co-Authors: Yongling Ruan, Rosemary G White, Robert T FurbankAbstract:Cotton Fibers are single-celled hairs that elongate to several centimeters long from the seed coat epidermis of the tetraploid species (Gossypium hirsutum and Gossypium barbadense). Thus, Cotton Fiber is a unique system to study the mechanisms of rapid cell expansion. Previous work has shown a transient closure of plasmodesmata during Fiber elongation (Y.-L. Ruan, D.J. Llewellyn, R.T. Furbank [2001] Plant Cell 13: 47–60). To examine the importance of this closure in Fiber elongation, we compared the duration of the plasmodesmata closure among different Cotton genotypes differing in Fiber length. Confocal imaging of the membrane-impermeant fluorescent molecule carboxyfluorescein revealed a genotypic difference in the duration of the plasmodesmata closure that positively correlates with Fiber length among three tetraploid genotypes and two diploid progenitors. In all cases, the closure occurred at the rapid phase of elongation. Aniline blue staining and immunolocalization studies showed that callose deposition and degradation at the Fiber base correlates with the timing of plasmodesmata closure and reopening, respectively. Northern analyses showed that the expression of a Fiber-specific β-1,3-glucanase gene, GhGluc1, was undetectable when callose was deposited at the Fiber base but became evident at the time of callose degradation. Genotypically, the level of GhGluc1 expression was high in the short Fiber genotype and weak in the intermediate and long Fiber genotypes. The data provide genotypic and developmental evidence that (1) plasmodesmata closure appears to play an important role in elongating Cotton Fibers, (2) callose deposition and degradation may be involved in the plasmodesmata closure and reopening, respectively, and (3) the expression of GhGluc1 could play a role in this process by degrading callose, thus opening the plasmodesmata.
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suppression of sucrose synthase gene expression represses Cotton Fiber cell initiation elongation and seed development
The Plant Cell, 2003Co-Authors: Yongling Ruan, Danny J Llewellyn, Robert T FurbankAbstract:Cotton is the most important textile crop as a result of its long cellulose-enriched mature Fibers. These single-celled hairs initiate at anthesis from the ovule epidermis. To date, genes proven to be critical for Fiber development have not been identified. Here, we examined the role of the sucrose synthase gene (Sus) in Cotton Fiber and seed by transforming Cotton with Sus suppression constructs. We focused our analysis on 0 to 3 days after anthesis (DAA) for early Fiber development and 25 DAA, when the Fiber and seed are maximal in size. Suppression of Sus activity by 70% or more in the ovule epidermis led to a Fiberless phenotype. The Fiber initials in those ovules were fewer and shrunken or collapsed. The level of Sus suppression correlated strongly with the degree of inhibition of Fiber initiation and elongation, probably as a result of the reduction of hexoses. By 25 DAA, a portion of the seeds in the fruit showed Sus suppression only in the seed coat Fibers and transfer cells but not in the endosperm and embryo. These transgenic seeds were identical to wild-type seeds except for much reduced Fiber growth. However, the remaining seeds in the fruit showed Sus suppression both in the seed coat and in the endosperm and embryo. These seeds were shrunken with loss of the transfer cells and were <5% of wild-type seed weight. These results demonstrate that Sus plays a rate-limiting role in the initiation and elongation of the single-celled Fibers. These analyses also show that suppression of Sus only in the maternal seed tissue represses Fiber development without affecting embryo development and seed size. Additional suppression in the endosperm and embryo inhibits their own development, which blocks the formation of adjacent seed coat transfer cells and arrests seed development entirely.
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the control of single celled Cotton Fiber elongation by developmentally reversible gating of plasmodesmata and coordinated expression of sucrose and k transporters and expansin
The Plant Cell, 2001Co-Authors: Yongling Ruan, Danny J Llewellyn, Robert T FurbankAbstract:Each Cotton Fiber is a single cell that elongates to 2.5 to 3.0 cm from the seed coat epidermis within ∼16 days after anthesis (DAA). To elucidate the mechanisms controlling this rapid elongation, we studied the gating of Fiber plasmodesmata and the expression of the cell wall–loosening gene expansin and plasma membrane transporters for sucrose and K+, the major osmotic solutes imported into Fibers. Confocal imaging of the membrane-impermeant fluorescent solute carboxyfluorescein (CF) revealed that the Fiber plasmodesmata were initially permeable to CF (0 to 9 DAA), but closed at ∼10 DAA and re-opened at 16 DAA. A developmental switch from simple to branched plasmodesmata was also observed in Fibers at 10 DAA. Coincident with the transient closure of the plasmodesmata, the sucrose and K+ transporter genes were expressed maximally in Fibers at 10 DAA with sucrose transporter proteins predominately localized at the Fiber base. Consequently, Fiber osmotic and turgor potentials were elevated, driving the rapid phase of elongation. The level of expansin mRNA, however, was high at the early phase of elongation (6 to 8 DAA) and decreased rapidly afterwards. The Fiber turgor was similar to the underlying seed coat cells at 6 to 10 DAA and after 16 DAA. These results suggest that Fiber elongation is initially achieved largely by cell wall loosening and finally terminated by increased wall rigidity and loss of higher turgor. To our knowledge, this study provides an unprecedented demonstration that the gating of plasmodesmata in a given cell is developmentally reversible and is coordinated with the expression of solute transporters and the cell wall–loosening gene. This integration of plasmodesmatal gating and gene expression appears to control Fiber cell elongation.
