Response of different cotton genotypes to salt stress and rewatering

Abstract Background: Cotton is a vital economic crop and reserve material and a pioneer crop planted on saline-alkaline soil. Improving the tolerance of cotton to saline alkaline environments is particularly important. Results: Salt-tolerant and salt-sensitive cotton plants at the three-leaf stage were subjected to 200 mM NaCl stress treatment, and microstructural observations and physiological and biochemical analyses were performed on cotton leaves at 0 h (CK), 48 h (NaCl) and re-watering (RW) for 48 h. Salt-tolerant materials showed better salt tolerance and faster recovery after re-watering than sensitive materials. Transcriptome analysis was performed on cotton leaves under salt stress and re-watering conditions. A total of 32,390 DEGs were identified between the two materials under the different treatments. KEGG analysis revealed that the response of cotton to salt stress and its adaptation to re-watering may be related to interactions such as photosynthesis (ko 00195), photosynthesis-antenna protein (ko 00196), plant hormone signal transduction (ko 04075), starch and sucrose metabolism (ko 00500), and porphyrin and chlorophyll metabolism (ko 00860). A gray coexpression module associated with cotton restoration under salt stress was enriched according to WGCNA. Conclusions: Salt stress not only affected the physiological and biochemical levels of cotton but also induced structural changes in cells and tissues, and re-watering alleviated the physiological and biochemical changes in cotton plants under salt stress. WGCNA revealed enriched gray coexpression modules related to the recovery of cotton plants under salt stress, and screening of the pivotal genes in the gray module revealed five critical hubs, namely, GH_A01G1528, GH_A08G2688, GH_D08G2683, GH_D01G1620 and GH_A10G0617. Overall, our findings can provide new insights into enhancing cotton salt tolerance and exploring salt tolerance genes in cotton.