Proteomic responses of oat (Avena sativa L.) to drought stress

Drought is a major abiotic factor limiting the growth and development of the oat industry, and understanding its drought tolerance mechanisms is vital to oat production. In this study, we measured the phenotypic and physiological indices of drought-resistant (Grain King [G]) and water-sensitive (XiYue [X]) oat varieties and performed comparative proteomic analysis under drought stress and normal water supply (soil water content of 75% {+/-} 5% of field water holding capacity) conditions. The results indicated that plant height, aboveground biomass, and underground biomass of variety X were 7.9%, 9.5%, and 14.6% lower than those under normal water supply, respectively, and the difference in plant height was significant (p < 0.05), whereas the decrease in all these indicators of variety G was small. Drought stress significantly increased malondialdehyde (MDA) content, soluble sugar (SS) content, superoxide dismutase (SOD) activity, and peroxidase (POD) activity of variety G by 48.6%, 68.5%, 81.3%, and 101.7%, respectively (p < 0.05). Variety X also showed increases up to various extents, but the increases were smaller than those of variety G. Additionally, 151 and 792 differentially expressed proteins (DEPs) identified in varieties G and X, respectively. Weighted Gene Co-expression Network Analysis(WGCNA), Gene Ontology(GO) and Kyoto Encyclopedia of Genes and Genome(KEGG) analyses demonstrated that the DEPs who were highly correlated with POD and SOD activity and SS content in variety G, were majorly involved in energy metabolism, protein translation, RNA processing, amino acid metabolism, and protein folding, whereas those with high correlation with the above three physiological indicators in variety X were primarily involved in RNA processing, protein stabilization, plant photosynthesis, intracellular signal transduction, and protein folding. Overall, the study elucidated the drought resistance mechanisms of different types of oats at the protein level