Discovery Of Genes Related To Fiber Development And Functional Analysis Of Cyclophilin(CYP) Gene In Gossypium Hirsutum L.

Cotton fibre is the most important natural textile fibre in the world.Among the four Gossypium species,the fibres length of upland cotton is generally 22?33 mm,while that of sea-island is 60 mm.Because of fibre slender,high strength and sea-island become an important raw material for high-grade cotton textile.In china,the sea-island is only planted in Xinjiang,and it contains high quality gene,which provides the gene resources for the fibre improvement of upland cotton.With the completion of cotton genomic sequencing,this provides a new opportunity for discovering excellent fibres quality genes and studying fibres development regulatory networks.In this study,Gossypium barbadense L.(Xinhai 21 fibres length:36.15 mm)and Gossypium hirsutum L.(Xinluzhong 36 fibres length:29.80 mm)were used as materials to study the gene expression profiles and proteome of sea-island cotton fibres at different stages.The main results are as follows:1.Based on the expression profiles and proteome quantitative integration data of the elongation period(5,10 DP A)of Xinhai 21 and Xinluzhong 36,and according to the genome of tetraploid sea-island,the candidate genes with different data at different stages and at the same time of different materials were analyzed in two Gossypium species.We obtained 119 differentially candidate genes,of which 62 genes were up-regulated and 57 genes were down-regulated.The up-regulated genes were mainly enriched in protein kinase activity,WD40 duplication,protein folding,hormone signal transduction,epidermal cell differentiation,trichomes differentiation,cell growth and others.Among them,8 genes expressed more differentially,there are 2 candidate genes encoded cyclophilin family proteins,respectively,and the others encoded vacuolar invertase family proteins,protodermal factors,membranous proteins,glycolaldehyde-3-phosphate dehydrogenase,chalcone-dihydro-flavone isomerase and phosphoric acid-2-dehydro-3-deoxy-heptonase.2.This study is the first time to identify CYP family genes from four Gossypium species.Using the Hidden Markov Model(HMM)profile of the PPIase domain(PF00160)as queries,a total of 75,78,40 and 38 predicted CYP gene sequences were identified from G.barbadense,G.hirsutum,G.arboreum and G.raimondii,all of them contained complete or partially conserved CLD(cyclophilin-like domain).These proteins were classified into three major groups according to their genetic relationship,segmental duplications that played a significant role in the expansion of CYP members.In addition,the motif composition analysis revealed that 49 cyclophilin proteins had extra domains,including TPR(tetratricopeptide repeat),coiled coil,U-box,RRM(RNA recognition motif),WD40(RNA recognition motif)and zinc finger domains,along with the CLD,suggesting that cyclophilin proteins have various biological functions in cotton.QRT-PCR showed that 35 GbCYPs were highly expressed in 5?20 DP A fibres.Furthermore,six GbCYPs expression levels showed greater differences between Xinhai 21(long fibres,G.barbadense)and Ashmon(short fibres,G.barbadense)at 10 and 20 days post anthesis(DP A).These results signified that GbCYP genes are involved in the elongation stage of cotton fibres development This study provides a valuable resource for further investigations of CYP gene functions and molecular mechanisms in cotton.3.GbCYP18-6 and GbCYP27-2 genes were cloned from Xinhai 21.QRT-PCR showed that both of the two genes expressed higher in the elongation period,and the highest expression was found in the 10 DPA fibres of Xinhai 21.The overexpressing CYP18-6 gene can promote the elongation of the primary root and root hair of the transgenic Arabidopsis thaliana,and the expression of the AtGLl is obviously increased.In addition,the overexpressing CYP27-2 gene can increase in the number of lateral roots and promote the elongation of root hair,and the expression of the AtTRY is obviously increased.The activity of PPIase in cotton was significantly decreased after VIGS silencing.The plant has the phenotype of slow growth,compact plant type,and small leaves,some of the plants silenced by GbCYP18-6 gene appeared early branching phenomenon,GbMYB25-like,GbMYB109 and GaHOX1 genes were Up-regulated,GbbHLH and GbSuSA were down-regulated expression of the plants silenced by GbCYP18-6.GbMYB109,GbbHLH and were down-regulated expression of the plants silenced by GbCYP2 7-2 It is suggested that CYP18-6 and CYP27-2 genes play a different role in the cotton fibres development.They may be involved in fibres development through signal transduction or regulation of sucrose synthase.