Primary Studies On Integrated Evaluation And Regulated Mechanism Of Semi-wild Cotton Under Complex Salt-alkali Stress

Salt and alkali stress is one of the main abiotic stress faced by crops,which seriously restricts the development of agricultural economy.Especially,in Xinjiang,the major region where plants cotton in China,one-third of arable land is salinization,and is basically a complex salt and alkali.Cotton is salt-resistant crop and is main crop growing in saline-alkali soil.To develop cotton in saline-alkali soil,especially in Xinjiang,is an important direction in China.Six accessions including four semi-wild and two cultivars in Gossypium hirsutum were evaluated for phonotypical,physiological and biochemical traits under alkali-salt versus normal conditions in hydroponic solutions.The tolerance of cotton to alkali-salt stress and its mechanism was determined based on principal component analysis,cluster analysis,correlation analysis,grey national analysis and analysis of variance.ROS production and clearance system related genes have been identified and analysed by studying the data of G.hirsutum races marie-galante 85,G.hirsutum races latifolium 40,zhongmian 16 and zhongmian 12 by RNA-seq.The main conclusions in this paper are as follows:1.The alkali-salt stress tolerance of the six accessions was ranked as: Marie-galante85 > Latifolium32 > CRI16 > CRI12 > Latifolium40 > Latifolium130.Among them,Marie-galante85,Latifolium32,and CRI16 were resistance salt and alkali.CRI12,Latifolium40,and Latifolium130 were sensitive to salt and alkali.2.And there is research to show that compared with the leaves,roots was more sensitive to saline and alkali stress.Active oxygen scavenging system was the main regulated network of the response of cotton to salt and alkali stress.And this study is suggested that the way responsing to alkali-salt stress under complex salt and alkali stress may be very complicated in cotton.Under the salt and alkali stress,the difference of ascorbate peroxidase and catalase activity was one of the reasons for the difference resistant levels of the four cotton accessions.3.265 ROS production and clearance-related genes were identified in the four cotton acessions.These genes include SOD,APX,MDAR,GR,GPX,Ferritin,Prx,CAT,AOX-related genes,GLR-related genes,TRX-related genes,NADPH oxidase-related genes.Among them SOD,APX,MDAR,GR,GPX,Ferritin,PRX,CAT,AOX,GLR,TRX were involved in the removal of ROS,and NADPH oxidase involved in the formation of ROS.Among the 265 genes that had been identified,247 ones had different expressed level.The genes expressed activity of ROS production and scavenging network may be induce the salt tolerance of cotton seedling under complex saline-alkali stress.What is more,58 genes had similar expression patterns in cotton leaves or roots and 3 genes were differentially expressed in roots and leaves of 4 cotton seedlings under salt and alkali stress,which were the most importanr genes to study the tolerant mechanism of cotton to alkali-salt stess and ROS regulated network responsing to alkali-salt stress.2 genes,which were normally expressed inthe salt-tolerant accesiions including Marie-galante85 and CRI16 but were differentially expressed in the salt-sensitive accesiions including CRI12 and Latifolium40,were the imporetant gene to study the reason of differences tolerance level of different cotton materials.