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. We have also investigated at the protein name and transcriptome level whether abscisic acid (ABA) pretreatment can make plants better equipped to cope with subsequent stress.
In one exemplar study, plants from 8 different Oryza sativa varieties, and two other rice species, were subjected to drought stress and recovery. 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 a second example, rice plants were subject to multiple abiotic stress conditions simultaneously, with or without prior treatment with the stress hormone ABA, and characterised in detail at both the proteomic and transcriptomic 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.
We found that pre-treatment with ABA significantly mitigated the leaf damage against combined abiotic stress at the proteome level. The application of exogenous ABA did not greatly affect the proteome profile of the control plants, while in stress-exposed plants a greater number of proteins were changed in abundance, most of which were increased. We also found that application of exogenous ABA to control plants under normal conditions did not alter the transcriptome profile significantly. The changes observed in the transcriptome of rice plants in response to multiple abiotic stress were made more pronounced by ABA pre-treatment, which induced the upregulation of a significant number of additional genes. Taken together, these results suggest that exogenous ABA has a potential priming effect for enhancing the rice tolerance of rice seedlings against combined abiotic stress, mainly by affecting stress-responsive mechanisms dependent on ABA signalling pathways in rice plants.