Analysis Of The Differential Gene Expression And Structure In Phenylpropanoid Pathway Of Developing Fiber Between Sea-island Cotton(Gossypium Barbadense L.) And Upland Cotton(Gossypium Hirsutum L.)

Cotton is the world’s one of the main economic crops, in recent years, along with the cotton textile industry development, and the increasing requirement of people for cotton quality cultivation of cotton varieties with both the high yield trait of Upland cotton and high quality fiber trait of Sea island cotton has become a dream of many plan breeders. Cotton fibers contain large amounts of cellulose and a small amount of lignin, which affects the properties of the cell wall. Biosynthesis of lignin is via the phenylpropanoid metabolic pathway in a series of enzyme catalytic formation of lignin monomer. In the present study, by comparison of gene expression in the phenylpropanoid metabolic pathway between Sea-island cotton and Upland cotton fiber in different development stages, in secondary wall development of cotton fiber, compare gene in island cotton and upland cotton in different, analysis of function of the key genes from phenylpropanoid metabolic pathway in cotton fiber development.By using RT-PCR method comparison of the expression of PAL1.4CL1, COMT1, CCR1etc. eighteen genes which are related to phenylpropanoid metabolism were performed between Sea-island cotton (Xinhai20) and Upland Cotton (Junmian1) in different developmental stages, three differentially expressed genes were selected to compare between Sea-island cotton and Upland cotton fiber by real-time fluorescence quantitative PCR method at different stages of development. There are significant differences for expression between Xinhai20and Junmian1. in Junmian1. PAL1,ACL1and C4H1gene expression quantity with the number increased. in15DPA the expression amount reaches a maximum, though PAL1,4CL1and C4H1gene expression were increased with the number of days, but the expression of the peak was20DPA in Sea-island Cotton (Xinhai20). The peak of expression for three genes was later in Sea-island cotton than in Upland cotton, and this was coincidence with the cotton fiber development and primary wall to the secondary wall developmental transition process.Primers were designed according to the cDNA sequence of cotton C4H1PCR method was used to clone C4H1from Sea-island cotton (Xinhai20) and Upland Cotton (Junmian1).They have some disparate points, for example:seventeen differences for basic radical, nine difference for amino acids, isoionic point and protein molecular mass. Although the amino acid disparate points did not appear in some important binding sites and functional zones, the expression of the gene was different in Xinhai20and Junmian1at different developmental stages. According to the phylogenetic tree, we found that the gene had some similarity with tobacco and woody plants. Because of the gene activity of C4H was connected with lignin and sclerenchyma, so it can be seen that C4H1gene may be involved in the regulation of cotton fiber cell elongation and secondary wall thickening, and it may influence formation of cotton fiber quality, this will be worth to further study.The significance of my study is, by analyzing the associativity between related genes for phenylpropanoid metabolism and secondary wall of cotton fiber, and comparing expression differences between Sea-island cotton and Upland cotton at different stages of fiber growth, it will have a lot of value to identify formation mechanism of fine fiber quality in sea-island cotton.