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棉 花 学 报 Cotton Science 2008，20(1)：62-69
Progress in Studies on Molecular Mechanism of Cotton Fiber Development and Quality Improvement Abstract：Cotton fiber development usually consists of four overlapping stages：fiber initiation, cell elongation, secondary cell wall formation, and maturation. Fiber length and strength are both key traits of its quality, and mainly depends on two biological processes: fiber elongation, secondary cell wall formation, respectively. Transcription factors and plant hormone play very important roles in the stage of fiber differentiation and initiation. The R2R3 MYB transcription factor GaMYB2 and WRKY transcription factors GhTTG1, GhTTG3，have been demonstrated playing significant roles in control cell fate determination. The genes encoding predicted proteins involved in auxin, brassinosteriod (BR), gibberellin acid (GA), abscisis acid (ABA) and ethylene signaling pathway are up-regulated in the period of fiber cell initiation. During fiber cell elongation period，many genes that represent three majors functional groups, including：cell wall structure and biogenesis, cytoskeleton, lipid and carbohydrate metabolism, show higher expression level. Plant hormones also play some regulatory roles in cotton fiber elongation. BR and ethylene can promote the fiber cell elongation in vitro culture. The initiation and rapid elongation of fiber requires the expression of sucrose synthase (SuSy), suppression of this gene represses fiber and seed development. Cellulose synthesis is a predominant event in fiber cells during in the secondary cell wall synthesis stage，cellulose synthase genes and SuSy are key regulatory and play significant role in this period. Based on the research of cotton fiber development at molecular level, improvement of fiber quality through genetic engineering has made some progress. For instance, over-producing spinach sucrose phosphate synthase to enhance fiber quality; transforming the acsA and acsB genes from Acetobacter xylinum, which are involved in cellulose synthesis, into cotton to improve the cotton fiber strength, etc. Color is also a main trait of cotton fiber and some progress has been made in produce color fiber through genetic engineering.
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