Response Of Mixure Salt-alkali In Semi-wild Cotton And Salt Stress Responsiveness Of A Wild Cotton Species (Gossypium Klotzschianum) Based On Transcriptomic Analysis

Cotton is an important fibre and energy crop and the pioneer crop planting in salt-alkali soil.While its production and quality still affected by high concentration salt,the production and quality of cotton are greatly restricted by the more and more serious soil salinization in for these years.Semi-wild cotton and wild cotton are the materials which screened through the rigorous natural environment evolution.Semi-wild cotton is the wild type of upland cotton,also named Gossypium hirsutum race,which contained abundant genetic diversity and also possessed genetic affinity with upland cotton cultivated varieties,is the good material of salt resistance mechanism research and salt resistance improvement.This study made the stability method in greenhouse of the mix salt-alkali resistance identification at germination and the seedling stage in semi-wild cotton,and preliminary discussed the response mechanism of ROS in semi-wild cotton under mix salt-alkali stress.The response mechanism of SOS,ROS and ABA-related genes in G.klotzschianum under high concentration NaCl stress was analysed by RNA-seq.The main results are as follows:1.Confirmation the method of determining the mix salt-alkali resistance of semi-wild cotton in greenhouse.The most suitable soil samples were obtained by the same identification results in greenhouse with that of the semi-wild cotton planted in saline land which locates in Xinjiang.Verification the feasibility of the identification method based on the determination of main ions contents in soil samples and obtained the resistance material MAR85,sensitive material LAT40,control resistance material CRI16 control sensitive material CRI12.2.Salinity-alkalinity stress response of semi-wild cotton at seeding stage.Phenotypic and physiological and biochemical displayed the differences of resistant physiological in four materials,and also the difference of antioxidant related enzyme.Gene expression pattern of roots and leaves of MAR85,LAT40,CRI16 and CRI12 treated with Mix salt-alkali for 0,3,12,48 h were investigated by RNA-seq on the Illumina-Solexa platform.In total,64,737 unigenes were identified from the transcriptome data,and there were more down-regulated genes than up-regulated genes.GO analysis showed that DEGs were significantly enriched in ROS-related pathways.3.Mix salt-alkali stress responsiveness of ROS-related enzymes and genes in semi-wild cotton.Gene function annotation uncovered that there were 265 ROS-related genes in these four materials.There were 152,124,144,131 ROS-related DEGs in CRI12,CRI16,LAT40,MAR85,respectively,involved the regulation of ROS.The mainly relevant genes which participated in ROS pathway were confirmed by the expression profiles analysis of SOD,POD,CAT,RBOH family genes.4.Salt stress responsiveness of a wild cotton species(G.klotzschianum)based on transcriptomic analysis.The phenotype identification showed the better salt tolerance of a wild diploid cotton species Gossypium klotzschianum after compared with G.davidsonii,which was proved salt tolerance.Firstly,detected the changes in hormone,H2O2 and glutathione(GSSH and GSH),then investigated the gene expression pattern of roots and leaves treated with 300 mM NaCl for 0,3,12,48 h,and each time control by RNA-seq on the Illumina-Solexa platform.Physiological determination proved that the significant increase in hormone ABA began at 48 h,while that in H2O2 was at 12 h,likewise,the GSH content decrease at 48 h and the GSSH content increase at 48 h,under salt stress.In total,37,278 unigenes were identified from the transcriptome data,8,312 and 6,732 differentially expressed genes(DEGs)were discovered to be involved in salt stress tolerance in roots and leaves,respectively.Gene function annotation and expression analysis elucidated hormone biosynthesis and signal transduction,reactive oxygen species(ROS),and SOS signal transduction related genes revealed the important roles of them in signal transmission,oxidation balance and ion homeostasis in response to salinity stress.5.High concentration salt stress responsiveness pathway in G.klotzschianum.The expression profiles of ionic transport,active oxygen and hormone-related genes revealed the important roles of SOS?ROS?ABA-related pathways.Combined with previous studies,drawn a hypothetical interaction network at early stage in response to salt stress in G.klotzschianum.