The Functional Characterization Of GhPCBER In Cotton Fiber Development

Cotton is an important economic crop in China,and the most important natural fiber crop in the world.China is the largest country in terms of cotton consumption and imports.It is also the largest producer of textile,and has the largest apparel production and trade.Because of the continuous progress of the textile industry,the improvement of people's living standards and the requirements of higher quality clothing,the improvement of cotton fiber quality is getting more important.Therefore,it is very urgent to look for high-quality genes and perform targeted molecular breeding.The fiber elongation and secondary cell wall synthesis stages decide the length,fineness and strength of the fiber.Therefore,in this study we will identify the function of a gene that is preferentially expressed in the fiber elongation and secondary cell wall synthesis stages,and expect to create a high-quality cotton material with this gene.We earlier cloned the gene GhPCBER in our laboratory,which was preferentially expressed in the fiber elongation and secondary cell wall synthesis stages.In this study,its role in fiber development was investigated by changing the expression of GhPCBER in transgenic cottons.The main results are as follow:1.Sequence alignment and expression analysis of the GhPCBER family in G.hirsutum showed that GhPCBER was more similar to At PCBER,it has an NADPH binding domain and is evolutionarily conserved.The expression pattern of PCBER was similar between sea island cotton and upland cotton.2.Low-copy transgenic plants with expected expression levels were screened by expression level detection and Southern blotting.The investigation of mature fiber showed that the Micronaire value of RNAi lines became lower and the length did not change significantly.The fiber length of the overexpression lines driven by the EXPA2 promoter was significantly longer,and the Micronaire value became lower.The mature fiber length of the overexpression lines driven by the 35 S promote was longer.The thickness of the cell wall of the overexpression lines was thinner through scanning electron microscopy of the cross section of the fiber.3.The lignin contents of the RNAi lines were increased,and consistent to the lignin contents the CAD expressions related to lignin synthesis were up-regulated in the RNAi lines and down-regulation in the overexpression lines.In summary,the above results suggested that up-regulation or down-regulation of expression of GhPCBER might affect fiber development by changing the synthesis of lignin in vivo,making GhPCBER over-expressed fibers become longer and thinner,and the fiber quality becomes better.This research provides some information to improve cotton fiber quality by investigating the function of GhPCBER in cotton fiber development.