Rice is one of the most important food crops in the world, and the productivity of rice crops is threatened by a number of different environmental stresses. We have investigated the proteomic response of rice varieties and species with different genetic backgrounds, when exposed to a range of different abiotic stresses, including drought, high and low temperatures, and salt.
Physiological parameters including leaf water potential and plant growth rates were measured. Proteins from tissues of young rice plants were extracted, peptides were separated using reversed phase nanoLC, and identified and quantified using high resolution orbitrap mass spectrometry, followed by peptide to spectrum matching.
This presentation integrates results from a number of different rice stress response studies performed in our laboratory in recent years. In one study, plants from 8 different rice varieties were subjected to drought stress and recovery. Proteins involved in proteolytic processing pathways were significantly increased in abundance, while many proteins significantly reduced in abundance in stress conditions were involved in photosynthesis. Some proteins were uniquely expressed in specific genotypes, while 8 proteins were up-regulated in response to drought stress in all genotypes, including actin-depolymerizing factor 3 (ADF-3) and GSH-dependent dehydroascorbate reductase 1. In a separate study, three different species of rice were exposed to drought stress: O. sativa cv. Nipponbare; Oryza australiensis; and Oryza glaberrima cv. CG14. The O. australiensis was able to retain more water in leaf cells than the other two species. A majority of proteins increased in abundance in stress conditions in O. australiensis were associated with photosynthesis and carbohydrate biosynthesis. A third study focused on phosphoproteomic analysis of O. sativa plants grown under control and drought stress conditions. Extensive changes were seen in proteins involved in membrane transport, including aquaporins, and also in proteins involved with carbohydrate metabolism and RNA processing.
Taken together, the results of these studies reveal important insights into the molecular mechanisms underlying stress response in rice, and also highlight the diversity of responses to stress seen in rice plants from a range of genetic backgrounds.