Identification Of Genes Related To Fiber Length And Strength And Cloning Of Important Gene In The Introgressed Line From Gossypium Hirsutum×Gossypium Barbadense

Cotton is one of the most widely cultivated fiber crops in the world.With the improvement of people’s living standards and the development of cotton textile industry,higher requirements for cotton fiber quality are put forward.Cotton fiber length and fiber strength are the important fiber quality traits.Bulked segregant RNA-Seq（BSR）have been widely used to screen candidate genes.In this study,the introgression line BC₇F₂ population was used to select individuals,sampling by BC₇F_2:3 population for BSR.A total of 8 RNA-seq libraries were constructed and sequenced respectively,including two parents and two pools with high and low fiber quality in 10 and 20 DPA（days post anthesis）.Transcriptome sequencing was used to identify differentially expressed genes（DEGs）.Compared CCRI36 with MBI9915,2434 and 3742 genes were differentially expressed in 10 DPA and 20 DPA,respectively.Considering two pools,there are 1360 and 3252 DEGs in 10 DPA and 20 DPA,respectively.355 and536 DEGs overlapped for two parents and the pooling in 10 and 20 DPA,respectively.A large number of DEGs have been found for same material at different stages.During the research,new genes were5060 and 5076 found in 10 and 20 DPA fiber samples.The differentially expressed genes of two parents and pools were annotated to GO database and KEGG pathway database.The new genes were annotated in GO database.The classification of new genes and differentially expressed genes was same in GO database.The SNP-index method was used for association analysis of two pools in 10 and 20 DPA,five correlated regions were obtained in 10 DPA,covering totally 11.84M,including 345 genes,in which 18were non synonymous mutations genes.2 DEGs overlapped in two pools and parents.The previous studies have found that these two genes may be related to cotton fiber strength and length.A total of 18regions were obtained in 20 DPA,one of them on Chrom.7 was consistent with the previous studies,including 1981 genes,in which 141 were non-synonymous mutation genes.12 DEGs overlapped in two parents and pools.The express level of 5 differentially expressed genes on chromosome 7 in 20 DPA were evaluated by quantitative real-time PCR（qRT-PCR）.The results showed quantitative real-time PCR were consistent with BSR-seq.Gh_A07G0837 were cloned in G.hirsutum CCRI36 and G.barbadense Hai 1.two base differences were identified between the two materials.Primary,secondary and tertiary structure of the protein encoded by Gh_A07G0837 was predicted.It lays a solid foundation for the functional research of cotton fiber length and strength related genes,and has certain guiding significance for promoting the research of cotton fiber quality.