Integrative comparative proteomics identifies core differentially expressed proteins and pathways for drought tolerance by exploiting contrasting rice varieties

Drought stress has been a severe challenge to world rice production. To elucidate the underlying mechanisms for rice drought adaptation, physiological characteristics, transcript expression patterns of related genes, and protein profiles from rice leaves were established for four rice cultivars with drastically different degrees of drought tolerance, and under drought stress, tolerant cultivars presented significantly reduced damage in growth and biomass retention. The loss in their main physiological characteristics was less than half of that in the sensitive varieties. Physiologically, the two tolerant varieties (303B and HY796) exhibited 30%–50% higher antioxidant enzyme activities, such as catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD), and a lower malondialdehyde (MDA) level, indicating effective cell membrane protection. Furthermore, there were also more strongly upregulated drought-responsive genes (such as OsDSM1 , OsCPK9 , and OsSNAC1 ) between the two varieties. A more tightly coordinated response was revealed at the protein level in the tolerant varieties via proteomic analysis. Carbohydrate metabolism, redox homeostasis, and protein transport were found to be activated in the tolerant varieties via functional enrichment analysis, while photosynthesis was suppressed. However, the networks of protein–protein interaction between more drought-tolerant lines were richer and well-connected. In the interaction networks of proteins, these two drought-tolerant lines had key hub proteins that play pivotal roles in effective signal transduction. The results systematically presented the complex regulatory network basis of drought resistance in rice and offered novel molecular targets for screening drought tolerance in rice.