Dynamic Analysis of Fiber Development Process and Proteomics of Ultra-High Strength Fiber in Upland Cotton
|School||Nanjing Agricultural College|
|Keywords||Cotton Elongation Microfibril Fiber Quality Proteome|
Cotton fiber is the leading natural fiber used as an important raw material for manufacture of textiles. In recent years, with the improvement of people’s living standard and rapid development of spinning technology, cotton fiber with higher quality traits is needed. Fiber elongation and secondary wall thickening stages take a large part of time in the course of cotton fiber development, fiber traits such as length, fineness, and strength are determined by fiber elongation and secondary wall thickening process to a great extent. Therefore, genetic improvement of cotton fiber quality depends on the research and modulation of the mechanisms underlying cotton fiber elongation and secondary cell wall thickening.In the present study, Suyou6167, an upland cotton line producing fibers of ultra-high strength, and TM-1, a genetic standard line of upland cotton generating fibers of average qualities, were used as materials to simultaneously analyze daily fluctuations of fiber length, fiber diameter and microfibril depositing direction during5-30DPA. Six key nodes in this process were identified. The proteomes of TM-1and Suyou6167fibers representing these six key nodes were examined by using two-dimensional gel electrophoresis coupled with mass spectrometry analysis, and15differentially expressed proteins were identified. The main research results are as follows:1. Fiber elongation. The overall elongation patterns of TM-1and Suyou6167were fairly similar:both of them underwent five distinct phases including slow elongation phase, rapid elongation phase, the first plateau phase, rapid shortening phase and the second plateau phase. During5-9DPA, fiber elongated slowly, from10DPA, however, fiber accelerated to grow in length until18DPA, during this period, there was an growth inflexion both in TM-1and Suyou6167, but the day of growing inflexion in Suyou6167was2days later than that in TM-1. Fibers achieved their maximum length at18DPA, and no significant difference was found between TM-1and Suyou6167. After a lag phase from18to22DPA, fibers began to be shortened in length at23and24DPA, and then kept stable until30DPA when fibers showed to be increased in length, and Suyou6167started to exceed TM-1. Given that the average mature fiber length of Suyou6167is usually5-6mm longer than that of TM-1, it is reasonable to believe that the final mature fiber length is not determined by the maximum length, but probably determined by the cell wall extensibility at maturation stage that was established by the fiber structure formed during elongation and second cell wall synthesis.2. Microfibril deposition angle. From5to10DPA, the microfibril angles of TM-1and Suyou6167were as big as70-80degree relative to the axial direction of the fiber, and then began to decrease at11DPA. The microfibril angle of Suyou6167dramatically declined to the minimum value of10degree within6days, while it took11days for TM-1to reach its minimum angle, moreover, there was a rebound process of2days (12-14DPA) during this period. Microfibril deposition pattern in combination with fiber elongation process make up the physical structure of cotton fibers, thereby playing determinant roles in cotton fiber qualities including fiber length and strength.3. Fiber diameter. TM-1and Suyou6167showed a slowly and parallelly decreasing trend in fiber diameters with fiber development throughout5to30DPA, therefore, the diameter of mature cotton fiber is mostly determined by its primary cell wall.4. Proteome analysis. According to the common and specific features of TM-1and Suyou6167in fiber elongation and microfibril deposition, six nodes including9,10,11,14,16, and20DPA were identified to be crucial for fiber development in these two cotton lines. Differential analyses of the fiber cell proteomes at these six time nodes of TM-1and Suyou6167were conducted by using2-DE technology,a total of252and127spots showed to be differentially expressed at different stages of TM-1and Suyou6167respectively, and383spots showed to be differentially expressed between TM-1and Suyou6167at same nodes.15protein spots showing significant difference and best repeatability were selected to digest in gel with trypsin followed by MS analysis, and fourteen of them were successfully identified. The identified proteins are related to non-cellulosic polysaccharides synthesis, ethylene biosynthesis, protein synthesis and processing, RNA processing and cellular redox homeostasis etc. The putative functions of these proteins in fiber elongation and secondary thickening are discussed. Our research provides new clues for revealing the mechanisms for ultra-high strength fiber development and formation.