The Relationship Between The Cellulose Synthesis And Cotton Fiber Quality

Cotton is widely grown economic crops in the world, is also the most important textile raw materials,the different varieties are required to breed for the the different uses of cotton fiber,but the fiber quality is aonly important selection criteria, cotton fiber strength is an important indicator of the fiber quality,which isalso determined whether the cotton fiber can be processed, in the pursuit of fiber strengh, at the sametime,people tend to ignore the impact of fiber length and fineness.A RIL population with196F6:8lines was developed from an F2population of Upland cotton(Gossypium hirsutum L.) cross of sGK9708×0-153.sGK9708is the commercial transgenic variety withBt+CpTI genes resistant to budworm,and0-153with high fiber quality.Four materials, which include thehigh-strength strain69307and a low-strength strain69362selected from the RIL population, and the islandcotton strain S-6with excellent fiber and upland standard line TM-1as control, were used to study thechange of fiber quality of the upper half of the fiber average length, strength, fineness and maturity indifferent days after flowering,fiber accumulation rate, the content of cellulose and expression of cellulosesynthase,the expression activity of pectin methylesterase which was seldomly reported in cotton, and thecorelation among the cellulose biosynthesis, pectin methylesterase and the fiber quality.(1)The overall trend of the fiber length shows "slow-fast-slow" in different days afterflowering..14-26DPA is a rapid period of fiber elongation, the duration of this time has an impact on theformation of fiber upper half mean length, the period of rapidly elongation is more,and the final fiberlonger;26-35DPA is a period of rapid change of the fiber strength, is also the critical period of formation ofthe fiber secondary cell wall, the overlap time of the fiber elongation and development of secondary cellwall is key to the formation of fiber strength. The period of after26DPA which is critical period to theformation of mature fiber length and fineness, and after35DPA is important to the formation of maturefiber strength, maturity and micronaire. So the control of the critical period could lead to the maximumfiber quality for the variety.(2)The period of20-26DPA is the rapid period of fiber accumulation, and the highest cellulose contentis on23DPA in which, the positive correlation is between fiber strength and fiber accumulation rate and cellulose content, but a significant negative correlation between fiber strength with pectin methylesteraseactivity, and the he high expression level of cellulose synthase is in the latter period, which control thebiosynthesis of cellulose,and influence the formation of the final fiber strength.(3)There is a significant positive correlation between the fiber upper half mean length,fiber strengthand cellulose cumulative rate,cellulose content, After26DPA but significant negative correlation betweenthe fiber fineness and pectin methylesterase activity. there is significant positive correlation between fiberupper half mean length and fiber maturity, micronaire on35DPA,while no obvious correlation betweenfiber strength and maturity,micronaire. there is a significant negative correlation between cellulose contentand fiber fineness, and a significant positive correlation between cellulose content and fiber maturity in theperiod of26-35DPA; and no obvious relationship between the cellulose accumulation rate and fibermaturity.The standard of a high-quality fiber characteristics should be the long, strong,and fine, as follows:thelonger period of fiber rapidly elongation and higher rate of elongation; the longer overlapping period offiber elongation and secondary cell wall; the faster and bigger speed of cellulose accumulation and longercumulative duration, the higher content of cellulose; relatively stable changes for fiber fineness andmaturity; the high expression of cellulose synthesis enzyme in the latter period of fiber development; andthe activity of pectin methylesterase increases with the fiber development, but still keep lower levels ofexpression.