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. This presentation integrates results from a number of different rice stress response studies performed in our laboratory over the years.
Physiological parameters including leaf water potential, photosynthetic and respiratory performance, 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.
In one study, plants from 8 different Oryza sativa varieties, and two other rice species, 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. O. australiensis was able to retain more water in leaf cells, than the other two species, and a majority of proteins increased in abundance in stress conditions in O. australiensis were associated with photosynthesis and carbohydrate biosynthesis.
In a second study, rice plants were subject to multiple abiotic stress conditions simultaneously, with or without prior treatment with the stress hormone ABA. Leaf tissue from these plants was characterised at the proteomics and transcriptomics level. This allowed us to tease apart the tightly integrated networks of genes and proteins involved, highlighting the role of the TCA cycle and photosynthesis related proteins in complex networks acting in both stress response and ABA signalling.
Our studies on abiotic stress in rice over many years have identified a large number of novel stress response proteins. We have begun the process of functionally characterising some of these, by expressing them in yeast cells and screening those for stress response phenotypes. Initial data from that study will be presented here, which shows that homologues of certain uncharacterised genes are able to confer resistance to various stresses in yeast.