Identification And Functional Analysis Of Flowering Key Genes In Cotton

Cotton is an important agricultural economic product in China.As the largest producer and consumer of cotton,the quality and yield of cotton in China are facing many challenges.Therefore,mining the important genes related to flowering time,analyzing the regulation pathway of cotton flower development,combined with molecular breeding methods,is conducive to cultivate early maturing varieties that ensuring cotton yield,quality and planting area.At the same time,it can alleviate the contradiction between grain and cotton for land,obtain double high yield of grain and cotton,effectively avoid the seasonal drought and other climatic factors and the mechanization degree should be increased to improve the fiber quality and yield of cotton breeding.This article takes Gossypium hirsutum L.,Gossypium raimondii,and Gossypium arboretum L.as the research objects,and uses the HMMER 3.0 software to identify their MADS-box,PEBP,LFY,COL family genes.Use MEME,MEGA 7.0,TBtools and Map Inspect software and omicshare website for motif prediction,multiple sequence alignment cluster analysis,gene structure identification,chromosome location and tissue-specific expression analysis.Use expression analysis,phylogenetic analysis results and fluorescence quantitative screening of key genes related to flowering in upland cotton,and further use gene cloning,Arabidopsis genetic transformation and virus induced gene silencing(VIGS)to verify gene function.The main conclusions are as follows:1.181,130 and 96 MADS-box genes were identified in upland cotton,Gossypium raimondii,and Asian cotton.The MADS-box protein in each cotton species can be divided into two types: Type I and MIKC.The MIKC type MADS-box protein contains AGL12,AGL17,AG,SVP,AGL15,BS,AP3/PI,SOC1,AP1,AGL6 and SEP subfamily and MIKC* type genes.Among them,AGL12 type protein is lacking in upland cotton.2.Through the whole-genome family identification,19,10,and 9 genes of the PEBP family in upland cotton,Gossypium raimondii,and Asian cotton were obtained.Phylogenetic analysis showed that the PEBP family proteins in each cotton species can be divided into four subfamilies: FT,TFL,MFT and PEBP.3.A total of 2,1,and 1 LFY genes in upland cotton,Gossypium raimondii,and Asian cotton were identified.The 4 genes all contain 3 exons,and the encoded protein contains the conserved domain SAM-LFY,with a protein length of 406 aa.4.There are 45,22 and 16 COL family genes in upland cotton,Gossypium raimondii,and Asian cotton,respectively.Phylogenetic analysis shows that the COL family proteins can be divided into three categories.Motif predictive analysis found that the COL protein contains one CCT domain and one or two B-box domains at the same time.5.According to the expression patterns,The MADS-box gene,PEBP gene,LFY gene and COL gene were mainly expressed in floral organs,fiber and leaf in upland cotton,while they were expressed in root,stem,leaf and fiber in Asian cotton.6.According to the results of phylogenetic analysis and expression pattern analysis,15 flowering-related key genes were screened: 3 SVP genes,4 COL genes,2LFY genes,2 AGL8 genes,3 SOC1 genes and 1 FT gene.7.The expression levels of GH＿A07G0749 and GH＿D07G0744 in early maturing cotton varieties were higher than those in late maturing cotton.8.Over-expressed genes GhAGL8-A07(GH＿A07G0749)or GhAGL8-D07(GH＿D07G0744)can promote early flowering of Arabidopsis for 3～5 days.VIGS GhAGL8 can delay the budding of upland cotton by 5～7 days and the flowering by3～5 days.It shows that the gene GhAGL8 can promote the flowering of plants.9.It is speculated that the genes GhAGL8-A07 and GhAGL8-D07 positively regulate the AP1 gene and have a negative regulatory relationship with the FT gene.