Differentially Expressed Proteins Analysis Of Seedling Leaf Of Cotton Under Salt Stress

Soil salinization affects the global crop production seriously. Cotton is one of the most importanteconomic crops, and the contradiction of food crop and cotton become prominent at present. The studyof response to salt stress in cotton can provide theoretical basis for breeding salt-tolerant cotton lines. Inthis study, we used the iTRAQ to study the differentially expressed proteins in Zao Shu Chang Rong-7(salt-tolerant line) and Nan Dan Ba Di Da Hua (salt-sensitive line) under different salt treatment points.Then we combined the physiological changes and gene level of cotton salt stress to the proteome resultsto reveal the cotton salt tolerance mechanism. The main results were as followed:1. Salt treatment for4h and24h under200mmol L-1NaCl can be used as the best treatmentcombination for cotton proteome analysis according to the relative electrolyte leakage change trend oftwo cotton lines; The results of relative electrolyte leakage, relative water content, chlorophyll contentsand Na+/K+of two cotton lines revealed that the salt-tolerant line had less damage than the salt-sensitiveone because of a higher relative water content, chlorophyll contents and a lower relative electrolyteleakage and Na+/K+.2. Pathway analysis of the total differentially expressed proteins of three repeats indicated that saltsensitive line coping with salt damage through passive slowing damage such as synthesis of osmoticsubstances, while the salt resistant one, mainly through the active response such as signal transductionand scavenging active oxygen. Obviously, the latter was more effective than the formar.3. The iTRAQ identified121differentially expressed proteins (DEPs) with high credibility, whichwere grouped into10functional classifications. The most important three were energy, protein synthesisand stress and defense; The expression pattern of the121proteins could be divided into three categories:the first category: twenty-four genotype-different DEPs without any salinity treatment; The secondcategory: fifty-five salt-responsive DEPs in both lines; The third class: thirty-nine genotype-specificsalt-responsive DEPs which included19and20proteins in salt-sensitive and-tolerant line, respectively;Then we selected19candidate proteins; Functional classification analysis showed that the cottonadjusted to the damage of salt stress mainly through photosynthesis and other energy process, reactiveoxygen removal and osmotic substances.4. The combined analysis of proteome and transcriptome showed that the overlap of proteins andgenes was very small. Only17proteins were matched to the transcriptome which were mainly involvedin energy and stress and defense; The correlation of genes and proteins showed that the salt-tolerant linehad a larger r than the-salt sensitive one; Fourty-six transcripts of17matched proteins were comparedwith the small RNA sequencing. Only three miRNAs were found. The corresponding target genes ofthree miRNAs were mainly involved in energy andthe synthesis of osmotic substances, which wereconsistent with the proteome results.The above results showed that the salt-tolerant line had less damage than the salt-sensitive one atthe physiological level. The proteome, combined with transcriptome and miRNA level all showed that the cotton adjusted to the salt stress mainly through the energy, reactive oxygen removal and osmoticsubstances.