Studies On Fiber Development Regulation And Experssion Patterns Of The Related Genes In Ramie

Ramie is a unique fiber crop in china, and the fiber products of ramie have many excellent qualities such as lightness, breathability, antibiosis, etc., so it plays an important role in the textile industry. However, poor crease resistance, fabric prickle and other reasons, which make textile of ramie be limited in domestic sale. One of the premise to solove the problem is to carry out the systematic study on ramie fiber development rules and mechanism, and studies in the past paid attention to physiological and cytological research. However, the studies on molecular mechanism of fiber development were rarely reported. The study selected “Dayelv” “Huazhu 5” “1504”, then combined with physiology, cytology and molecular biology to explore the fiber development rules of ramie. The first step was to conduct microscopic observation of fibroblast development status in different growth stages of ramie, and study on diversification of fiber components content during fiber development. The next step was to study on expression patterns of genes associated with fiber components biosynthesis during fiber development. The purpose of this study was to explore the general rules of ramie fiber development, which provide theoretical bases for regulating fiber development, improving fiber quality further, and providing a reference for analytical development mechanism in molecular biology preliminarily.The results are shown as folows:1.Fiber development of ramie main experienced three phases: fibroblast differentiation, cell elongation, secondary wall thickening. At the same position, fiber layer thickness was increased and no differences in fiber layers in three ramie varieties with fiber development, these results indicated that fiber layer had form a certain number of fibroblasts, and the increase of fiber layer thickness was due to fibroblasts become large and secondary wall thickening constantly. The fiber layer thickness/ fiber layers of “1504” was significantly lower than “Dayelv” and “Huazhu 5” in every stage, this result had consistency with the mature fiber diameter of “1504” was significantly lower than “Dayelv” and “Huazhu 5”. These studys showed that early development of fiber play an important role on fiber quality.2.At the same position, the content of cellulose and lignin were increased, and the content of pectin and hemicellulose were decreased, the cellulose content were highest and the lignin content were lowest in every stage. Content of each component were different in three varieties. In the mature fiber, the cellulose content of “Huazhu 5” and “1504” were significantly higher than “Dayelv”; the content of “Huazhu 5” and “1504” were significantly lower than “Dayelv”; the pectin content of “Dayelv” were highest and “Huazhu 5” were lowest, and three varieties had significant differences; the lignin content of “Dayelv” were significantly higher than “Huazhu 5” and “1504”. Every index of quality among three varieties was different, the adhesive content of “Dayelv” were highest and “1504” were lowest; the breaking force of “Dayelv” and “Huazhu 5” were significantly higher than “1504”; the elongation at break of “Dayelv” were highest and “1504” were lowest; the diameter of “Dayelv” and “Huazhu 5” were significantly higher than “1504”.These results indicated that the effects of fiber components content on the fiber quality were not decided by one component content, and it may be associated with the content ratio and structure of every component.3.The study on expression patterns of genes associated with fiber components biosynthesis during fiber development showed that all of genes were expressed in different parts of stem, but there were differential expression with all of genes. The members of CesA family and UGPase family as well as UGlcAE all had relative expression peak in seedling stage of the second harvest, the members of GalAT family all had relative expression peak in the quick growth stage of the first harvest. The correlation analysis on the expression patterns of every gene showed that: CesA1, CesA2, CesA6; CesA3, CesA4, CesA7, CesA8; GalAT1, GalAT2, GalAT6, GalAT7; COMT2, COMT3; PAL1, PAL3 had high correlation, the correlation of every two genes were more than 0.85 except PAL1 with PAL3, these results indicated that different genes involved in a synergistic role in the synthesis of fiber components.