Identification Of Genes Related To Cotton Yield Using Gene Chips

Cotton is a major economic crop and an important variety for the Chinese textile industry. Since grain and cotton production compete for the same land resource, there is a conflict in China with increasing population and decreasing arable land, so how to breed varieties with high yield and good quality is always the breeder's target.Land cotton is widely cultivated because of its high yield, and the sea island cotton is famous of its good fiber quality, so how to mix the high yield of land cotton and the good quality of sea island together to breed new varieties with high yield and good quality, and then do more research of the genes related to high yield and good quality by the cross of land cotton and sea island cotton, they are goals for breeders. In this research, the genes related to cotton yield were researched, the gene chip of Affymetrix and the backcross inbred lines of land cotton and sea island cotton are used. The main results are as follows:1. The backcross inbred lines of BC2F5 were cultivated by the land cotton SG747 as the female parent and the sea island cotton Giza75 as the male parent. Totally 19 different genotypes were selected, and their fiber cDNAs of 10 days past anthesis were hybridized with the cotton gene chip of Affymetrix. Based on the above works, this research use the field data of the traits related to yield(lint yield,boll weight and lint percentage), and three years'data on 2006,2007,2008 were used. Then, do the ANOVO analysis with the SAS software, and select 3 genotypes separately of high lint yield and low lint yield,high boll size and low boll size and high lint percentage and low lint percentage, and every genotype in the high group is significant different with the low group of the single trait.2. For the gene chip data comparasion,1508 differentially expressed (DE) genes were identified based on a two fold difference between the high lint yield and the low lint yield group,296 differentially expressed genes between the high boll size and the low boll size group,351 differentially expressed genes between the high lint percentage and low lint percentage group.185 differential expressed gene were common in lint yield and boll size,96 differential expressed genes were common in lint yield and lint percentage, 7 differential expressed genes in boll size and lint percentage, and 51 differential expressed genes in all three traits.3. Bioinformatic analysis of these three traits were done by the Blast2GO software, and the results of clustering at biological process,cellular component and molecular function were grained. The results shows that, there are more genes related to the cellular component of plasma membrane, related to the molecular function of Oxidation reduction, related to the biological processes of response to the stress and transport.4. Select 50 differential expressed genes of the three traits separately, totally 150 genes, and no duplicate in these 150 genes. First, do the RT-PCR analysis on these 150 differential expressed genes, then select some gene according to the RT-PCR results to do the qRT-PCR analysis.5. According to the RT-PCR results, eight genes were preferentially expressed in the high yielding group or vice versa, in order to validate the results, the eight genes from the lint yield were selected to do the qRT-PCR, the results indicated that the two genes GhMKRP2 and GhPOD may be involved in the development of cotton fibers which in turn affect the cotton yield.