Gotowa bibliografia na temat „Cotton fiber initiation”

Abstract Cotton, one of the most important crops in the world, produces natural fiber materials for the textile industry. WRKY transcription factors play important roles in plant development and stress responses. However, little is known about whether and how WRKY transcription factors regulate fiber development of cotton so far. In this study, we show that a fiber-preferential WRKY transcription factor, GhWRKY16, positively regulates fiber initiation and elongation. GhWRKY16-silenced transgenic cotton displayed a remarkably reduced number of fiber protrusions on the ovule and shorter fibers compared to the wild-type. During early fiber development, GhWRKY16 directly binds to the promoters of GhHOX3, GhMYB109, GhCesA6D-D11, and GhMYB25 to induce their expression, thereby promoting fiber initiation and elongation. Moreover, GhWRKY16 is phosphorylated by the mitogen-activated protein kinase GhMPK3-1 at residues T-130 and S-260. Phosphorylated GhWRKY16 directly activates the transcription of GhMYB25, GhHOX3, GhMYB109, and GhCesA6D-D11 for early fiber development. Thus, our data demonstrate that GhWRKY16 plays a crucial role in fiber initiation and elongation, and that GhWRKY16 phosphorylation by GhMPK3-1 is essential for the transcriptional activation on downstream genes during the fiber development of cotton.

AbstractAuxin-dependent cell expansion is crucial for initiation of fiber cells in cotton (Gossypium hirsutum), which ultimately determines fiber yield and quality. However, the regulation of this process is far from being well understood. In this study, we demonstrate an antagonistic effect between cytokinin (CK) and auxin on cotton fiber initiation. In vitro and in planta experiments indicate that enhanced CK levels can reduce auxin accumulation in the ovule integument, which may account for the defects in the fiberless mutant xu142fl. In turn, supplementation with auxin can recover fiber growth of CK-treated ovules and mutant ovules. We further found that GhPIN3a is a key auxin transporter for fiber-cell initiation and is polarly localized to the plasma membranes of non-fiber cells, but not to those of fiber cells. This polar localization allows auxin to be transported within the ovule integument while specifically accumulating in fiber cells. We show that CKs antagonize the promotive effect of auxin on fiber cell initiation by undermining asymmetric accumulation of auxin in the ovule epidermis through down-regulation of GhPIN3a and disturbance of the polar localization of the protein.

WD40 repeat proteins are largely distributed across the plant kingdom and play an important role in diverse biological activities. In this work, we performed genome-wide identification, characterization, and expression level analysis of WD40 genes in cotton. A total of 579, 318, and 313 WD40 genes were found in Gossypium hirsutum, G. arboreum, and G. raimondii, respectively. Based on phylogenetic tree analyses, WD40 genes were divided into 11 groups with high similarities in exon/intron features and protein domains within the group. Expression analysis of WD40 genes showed differential expression at different stages of cotton fiber development (0 and 8 DPA) and cotton stem. A number of miRNAs were identified to target WD40 genes that are significantly involved in cotton fiber development during the initiation and elongation stages. These include miR156, miR160, miR162, miR164, miR166, miR167, miR169, miR171, miR172, miR393, miR396, miR398, miR2950, and miR7505. The findings provide a stronger indication of WD40 gene function and their involvement in the regulation of cotton fiber development during the initiation and elongation stages.

During cotton fibers development, important structural changes occur, which lead to cellulose deposition and organization in the secondary cell wall. Several studies have focused on the analysis of the cell wall extracts of cotton fibers to gain an understanding of the changes in carbohydrate profiles and to determine the changes in crystallinity, cellulosic and non-cellulosic compounds at various stages of the fiber cell wall development. In this research, thermogravimetric analysis (TGA) was used to study intact fibers harvested from two cotton genotypes. Cellulose macromolecules structural changes occurring during different developmental stages were studied. The results from TGA technique were in agreement with results from other analytical techniques, which indicates that TGA could be a great tool to investigate the onset of cellulose deposition and to evaluate the cell wall composition during fiber development. The results obtained in this study demonstrated that the initiation of the secondary cell wall is genotype-dependent.

Upland cotton is the most widely planted for natural fiber around the world, and either lint percentage (LP) or fiber length (FL) is the crucial component tremendously affecting cotton yield and fiber quality, respectively. In this study, two lines MBZ70-053 and MBZ70-236 derived from G. hirsutum CCRI70 recombinant inbred line (RIL) population presenting different phenotypes in LP and FL traits were chosen to conduct RNA sequencing on ovule and fiber samples, aiming at exploring the differences of molecular and genetic mechanisms during cotton fiber initiation and elongation stages. As a result, 249/128, 369/206, 4296/1198 and 3547/2129 up-/down- regulated differentially expressed genes (DGEs) in L2 were obtained at −3, 0, 5 and 10 days post-anthesis (DPA), respectively. Seven gene expression profiles were discriminated using Short Time-series Expression Miner (STEM) analysis; seven modules and hub genes were identified using weighted gene co-expression network analysis. The DEGs were mainly enriched into energetic metabolism and accumulating as well as auxin signaling pathway in initiation and elongation stages, respectively. Meanwhile, 29 hub genes were identified as 14-3-3ω, TBL35, GhACS, PME3, GAMMA-TIP, PUM-7, etc., where the DEGs and hub genes revealed the genetic and molecular mechanisms and differences during cotton fiber development.

A quantitative electron microscopic (E/M) study of the changes in microtubule arrays and wall microfibril orientation has been done on in vitro grown cotton fibers. Microtubules change orientation during cotton fiber development. During fiber initiation and early elongation, microtubules have a generally random orientation. Microtubules re-orient into shallow pitched helices as elongation and primary wall deposition continue, and into steeply pitched helices during secondary wall deposition. Accompanying the changes in orientation are increases in microtubule length, number, proximity to the plasmalemma and a decreased variability in orientation of the microtubules. Based on these observations, three pivotal stages in microtubule patterns were identified during fiber development: (1) the transition between fiber initiation and elongation, where microtubules develop a shallow pitched helical orientation; (2) the transition between primary and secondary wall synthesis, where microtubules abruptly shift orientation to a steeply pitched helical pattern; and (3) early in secondary wall synthesis, where there is a four fold increase in microtubule number. Microfibrils exhibit changes in orientation similar to the microtubules; however significant differences were found when the precise orientations of microtubules and microfibrils were compared. During secondary wall synthesis, wall microfibrils exhibit some variability in orientation due to inter-fibril bundling, thus indicating that components of the wall may also influence final microfibril orientation.

Gossypium barbadense is an important source of natural textile fibers, as is Gossypium hirsutum. Cotton fiber development is often affected by various environmental factors, such as abnormal temperature. However, little is known about the underlying mechanisms of temperature regulating the fuzz fiber initiation. In this study, we reveal that high temperatures (HT) accelerate fiber development, improve fiber quality, and induced fuzz initiation of a thermo-sensitive G. barbadense variety L7009. It was proved that fuzz initiation was inhibited by low temperature (LT), and 4 dpa was the stage most susceptible to temperature stress during the fuzz initiation period. A total of 43,826 differentially expressed genes (DEGs) were identified through comparative transcriptome analysis. Of these, 9667 were involved in fiber development and temperature response with 901 transcription factor genes and 189 genes related to plant hormone signal transduction. Further analysis of gene expression patterns revealed that 240 genes were potentially involved in fuzz initiation induced by high temperature. Functional annotation revealed that the candidate genes related to fuzz initiation were significantly involved in the asparagine biosynthetic process, cell wall biosynthesis, and stress response. The expression trends of sixteen genes randomly selected from the RNA-seq data were almost consistent with the results of qRT-PCR. Our study revealed several potential candidate genes and pathways related to fuzz initiation induced by high temperature. This provides a new view of temperature-induced tissue and organ development in Gossypium barbadense.

Cotton fiber development is a fundamental biological phenomenon. In spite of its economical importance, a large proportion of cotton fiber initiation is unknown. A naked seed mutant (N1N1) was compared with its isogenic lines of cotton (Gossypium hirsutum, TM-1) using a 70-mer oligonucleotide microarray that contained 1,536 features designed from a subset of cotton fiber ESTs. Statistical analysis and quantitative RT-PCR identified 23 "fiber-associated" genes. The annotation suggested that the temporal regulation of genes involved in transcriptional and translational regulation, signal transduction, and cell differentiation during early stages of fiber development. To get a large view of fiber initiation, a new cotton oligonucleotide microarray was developed containing sequences from an ovule EST library from Gossypium hirsutum L. T̲M̲-1 immature o̲vules (GH_TMO), a set from Jonathan Wendel's lab at Iowa State University, and the pilot set of oligos used for previous study. Global gene expression studies were performed with microdissected fiber initials (or epidermis) and inner ovules to investigate fiber preferentially expressed genes. Laser capture microdissection and antisense RNA (aRNA) amplification allowed us to collect fiber initials (0 DPA and 2 DPA) or epidermal layers (-2 DPA) from whole ovule tissues. The gene expression profiles of fiber initials showed up-regulation of fiber proteins, myb transcription factors, and hormonal regulators as well as trichome related factors during fiber initiation. In each developmental stage, different sets of gene categories in molecular function or biological processes were over- or under-represented, suggesting temporal regulation of genes during fiber development. One of the possible "fiber associated genes" found in microarray analyses, RD22 like gene (GhRDL), was highly enriched in the epidermis of cotton ovules during fiber initiation. The function of GhRDL was studied with the Arabidopsis trichome system which shares many similarities with fiber development. Overexpression of 35S::GhRDL into Arabidopsis thaliana Columia-0 induced seed hairs (or seed trichomes) and pRDL:GUS was localized in Arabidopsis seeds. This suggests that GhRDL plays an important role in the seed trichome development and can be a key player in cell differentiation and fiber development.
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Title page, contents and abstract only. The complete thesis in print form is available from the University of Adelaide Library.
Cotton fibres are single-celled hairs, arising from the epidermal surface of the cotton ovule. One factor in determining the length of the mature cotton fibre is the timing of fibre initiation, which is therefore a crucial step in obtaining commercial cotton fibres. To achieve a greater understanding of the regulation of cotton fibre differentiation, more fundamental information is needed on the signals and mechanisms associated with fibre initiation. The extensive genetic knowledge of Arabidopsis leaf trichomes could aid in the elucidation of the genetic mechanisms controlling cotton fibre differentiation. Trichomes are small hairs on the plant surface, originating from single epidermal cells in a developmental process that appears very similar to that of cotton fibres. Arabidopsis trichome development has been extensively investigated, and several genes that control the process have been characterised. One gene essential for trichome initiation is TRANSPARENT TESTA GLABRAI (TTGI), and loss-of-function mutations in TTGI result in an almost complete absence of leaf trichomes. TTG 1 plays additional roles in numerous pathways in Arabidopsis, including root hair initiation, anthocyanin production and seed coat mucilage production. In order to isolate genes required for fibre initiation in cotton, functional homologues of Arabidopsis TTG 1 in cotton have been sought. Four putative homologues of Arabidopsis TTG 1 have previously been isolated in this laboratory by RT-PCR of mRNA prepared from cotton fibres, and are termed GhTTG 1-4. Sequence comparisons between the four cotton deduced proteins and Arabidopsis TTG 1 showed that they form two groups, with GhTTG 1 and GhTTG3 being closely related to each other (87% identical and 93% similar) and to TTG 1 (79% and 80% amino acid identity respectively). GhTTG2 and GhTTG4 formed the second group, with 95% amino acid identity to each other and lower (approximately 62%) identity to TTG 1. An analysis of the genomic origins of the GhTTG genes demonstrated that each is derived from the same ancestral diploid genome. Cross-species complementation experiments were performed to test for functional homology of these cotton TTG I-like genes to AtTTG 1, by introducing the cotton genes into Arabidopis ttgI-I mutants via Agrobacterium-mediated transformation. This experiment showed that two of the four genes, GhTTGl and GhTTG3 were able to restore trichome initiation in the Arabidopsis mutant plants, and a further investigation of GhTTG3 transgenic plants demonstrated complementation of the full range of ttgl mutant phenotypes. An analysis of the temporal and spatial expression of the GhTTG genes in cotton is also described. It was shown that each of the genes is expressed ubiquitously throughout the cotton plant, in common with many plant WD-repeat genes. A closer examination of transcript abundance in the developing cotton ovule utilising in situ hybridisation revealed predominant expression of GhTTG lIGhTTG3 in the epidermal cells destined to become cotton fibres. A yeast two-hybrid assay was utilised to identify transcription factors that may interact with GhTTG3 during .fibre development. This experiment identified three cotton fibre cDNAs encoding putative interacting proteins, including one with a similar secondary structure to several TTG I-interacting proteins in Arabidopsis, raising the possibility of similar regulat01;y-complexes controlling trichome initiation in Arabidopsis and cotton.
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Thesis (Ph.D.) -- University of Adelaide, School of Molecular and Biomedical Science, 2007

Bearing in mind that undergraduate students must get involved in research and that local industry must be a university partner, the School of Engineering, from University of Minho, has taken the initiative in funding some technical research projects in specifically defined areas (http://www.eng.uminho.pt). In this context, one of the projects founded concerns the development and testing of functional knitting which can be used with success in the lining of a shoe. The study of shoe comfort is of great importance to sport and leisure footwear manufactures, because in these particular situations, moisture disposal over a number of hours is a main problem. Three structures which combine different raw materials (soybean fiber, bamboo fiber, corn fiber, cotton, polypropylene and polyester) have been manufactured by a local textile factory. A group of students mainly from Mechanical and Textile Engineering classes are currently testing these knitting in terms of their water vapor and air permeability and other physical parameters at the laboratory. Tests with a thermal manikin have been used to measure its thermal insulation. A transient model for heat and mass transfer in a fabric has been implemented. From the solution, temperature and vapor density profiles in the fabric thickness can be obtained as well as, the amount of water dissolved in the fabric. This model has been integrated with an existing human thermal comfort model. Thermal comfort surveys are now being made at the Ergonomics Laboratory of the University of Minho with undergraduate Mechanical and Industrial Engineering students, wearing sport shoes manufactured by a local footwear factory, and these results can be compared using statistical analysis, with the experimental and numerical results already obtained.