Comparative Root Transcriptome Revealed The Salt Stress Response And Tolerance Mechanism In The Upland Cotton

Soil sanilization is one of the important abiotic stress factors that limit crop production. Soils are classified as saline when the ECe is4dS/m or more, which is equivalent to approximately40mM NaCl. Improving salt tolerance of crops has become an urgent breeding problem. The upland cotton is the most important domesticated fiber plant with highly salt tolerance to the ECe is7.7dS/m, which was recognized as a’pioneer crop’for the salinity soil utilization and suitable model plant for salt stress tolerance study, which had received widespread attention for the molecular mechanism study.Here, seven full-length cDNA libraries were constructed for seedling roots of salt-sensitive upland cotton’Zhong G5’at Oh,3h,12h and48h after the treatment of control or150mM NaCl stress. About3,300colonies in each library were selected robotically for5’-end pyrosequencing resulting in20,358expressed sequence tags (ESTs).8,516uniESTs were then assembled, including2914contigs and5602singletons, and explored for Gene Ontology (GO) function using BLAST2GO.GO comparison between serial stress and control libraries reflected the growth regulation, stimulus response, signal transduction and biology regulation processes were conducted dynamically in response to salt stress. And the transcription factors comparison uncovered that MYB, MYB-related, WRKY, bHLH, GRAS and ERF families of transcription factors were significantly enriched in the early response.65differentially expressed genes (DEGs), mainly associated with reactive oxygen species (ROS) scavenging, gibberellins (GAs) metabolism, signal transduction, transcription regulation, stress response and transmembrance transport, were identified by Fisher exact test and confirmed by quantitative real-time PCR. Over-expression of selected DEGs increased tolerance against salt stress in transgenic yeast. Results in this study supported that a ROS-GAs interacting salt stress response signaling pathway was activated in upland cotton. Agreed with the relationship between the fluctuation of the ROS levels and the response of the GAs metabolism in Arabidopisis, a model for the ROS-GAs interacting signaling pathway in upland cotton responded to salt stress was proposed.By comparing the large-scale ESTs of control and stress libraries at series times, a dynamic salt stress response process in cotton root was discovered firstly and multiple signaling crosstalking in cotton salt tolerance was proposed. In addition, our results provided valuable gene resources for further investigation of the molecular mechanism of salinity tolerance and for genetic improvement of cotton.