Map Cloning And Functional Analysis Of Cotton Short Fruit Branch Internode Genes(GhSBI)

Cotton is an important economic crop in the world and an important source of natural fibers in the textile industry.Increasing cotton production,adapting to mechanical harvesting,and reducing production costs are inevitable ways to improve China’s cotton international competitiveness and ensure sustainable development.Studying cotton plant type and its regulation is an efficient technical way to increase yield and adapt to mechanization needs.In this study,the length traits of cotton fruit branches were studied.The normal fruit branch internode length material TM-1 and the short fruit branch internode material Chuannong 72318 were used as experimental materials,and GhSBI(Short Fruit Branch Internode)gene localization was carried out by BSA-Seq,followed by Functional verification and analysis.The main results are as follows:(1)Chuannong 72318 is a natural mutant material with the length of fruit branch internode traits.Its internode length is only 14.33% of the upland cotton standard line TM-1.By observing the internode cells of the fruit branches,it was found that Chuannong 72318 and TM-1 differs in cell number and cell length,and the number of cells is the main cause of the difference in internode length.(2)The follow-up experiment was carried out with TM-1 as the female parent and Chuanong72318 as the male parent.The results showed that the internode length of F1 plants tends to be TM-1.Therefore,it is determined that the GhSBI gene controlling the traits of Chuanong 72318 short fruit branch internode is a recessive gene.The GhSBI gene was mapped to the 5-6 Mb region of the D01 chromosome using the BSA-Seq gene mapping method.Within this interval,NAC098 is a candidate gene due to a NAC transcription factor regulated by microRNA164.(3)Combined with public database data and qRT-PCR results,GhSBI gene was highly expressed at the shoot tip of the fruit,and the expression of Ghsbi was significantly higher than that of GhSBI.The PPM-RACE test results showed that there was a base mutation in the target region on Ghsbi,which affected the recognition of microRNA164,and the mRNA could not be cleaved,resulting in a significantly higher expression of Ghsbi than GhSBI.(4)The overexpression vector was constructed using Ghsbi as a template for Arabidopsis thaliana and cotton transformation experiments.For the T2 transgenic Arabidopsis,it was found that there was no difference between transgenic Arabidopsis and wild type.Cotton is a hinged growth plant.Arabidopsis is a uniaxially grown plant with no fruit branches.Therefore,Ghsbi function cannot be determined by transgenic Arabidopsis.Cotton transgenic trials are still in progress.The functional verification test also carried out the cotton RNAi test,which is still in progress.(5)Through the investigation of the internode elongation process of Chuanong 72318 and TM-1,it was found that the speed during the inter-segment elongation accorded with the "slow-fast-slow" elongation law,and based on this,the transcriptome test was carried out.GhSBI was found to be associated with the synthesis of Auxin,Gibberelin,Cotykinine,and Brassinosteroid,and may be regulated by the GhSBI gene to control internode elongation.