Comparative Study on Growth and Proteomics of Oats Under Alkali Stress in Heading Stage

Alkaline soils occupy the vast majority of the salinized soils in the world, and alkali stress always induces more serious stress to plants, which suppresses plants growth and development, restrains grain yield greatly. To dissect the mechanism of the oat in response to alkali stress in the heading stage, an alkali-tolerant (Vao-9) and an alkali-sensitive (Xin-17) cultivar were employed. The tolerant cultivar Vao-9 grew and developed well in the heading stage even under high concentrations of alkali stress (100 mM mixed alkali). However, the height and panicle development of the sensitive cultivar Xin-17 were significantly restrained. Moreover, dehydrating and yellowing of leaves indicated that many biological processes were affected deeply by the alkali stress in the sensitive cultivars. To better understand the mechanism, the proteomics-based label-free and parallel reaction monitoring (PRM) technique were used. About 1572 proteins in Xin-17 and 1657 proteins in Vao-9 were identified, in them, 11 DEPs in Vao-9 and 73 DEPs in Xin-17 were found. Above all, the synthesis of ribosomal subunit components in the sensitive cultivars was greatly restrained to inhibit the synthesis of proteins under the alkali stress, which involved in many biological processes. Then, many photosystem components in sensitive cultivars downregulated, which suppressed the efficiency of photosynthesis to lead to the net photosynthesis rate decreased quickly under alkali stress. On the other hand, many enzymes involved in carbohydrate metabolism and amino acid metabolism upregulated to maintain the basic metabolism, and amounts of enzymes in the antioxidative reaction and secondary metabolism increased to help to resistant to the alkali stress in the sensitive cultivars. Ultimately, these increased DEPs would cause a lot of energy consumption to weaken the sensitive cultivars.