Proteomic dissection of the similar and different responses of wheat to drought, salinity and submergence during seed germination.

Wheat (Triticum aestivum L.) is one of the major crops worldwide and its production is inevitably subjected to various biotic/abiotic stresses during the life cycle. Drought, salinity and flooding are among the most severe abiotic stresses restricting wheat yields and could occur at very early stages such as seed germination. How wheat seed germination responds to these different stresses remains incomplete. To fill the information gap, a label-free proteomic analysis was applied to decipher the proteomic profiling of the germinating wheat seeds subjected to PEG, NaCl and submergence treatments. In total, 4295 proteins were detected, of which 465, 397 and 732 showed significant alterations in abundance under those stresses when compared with control. A common denominator found in the response observed to all three stresses are changes related to small molecule metabolic processes, and particularly in pathways associated with phenylpropanoid biosynthesis and fatty acid degradation. It was also noticeable that pathways like cysteine and methionine metabolism in the PEG or submergence treatment and starch and sucrose metabolism in the submergence treatment are specifically pronounced. Functional analysis of putative proteins participating in these pathways revealed distinct responsive patterns across different stresses. SIGNIFICANCE: Wheat (Triticum aestivum L.) is one of the most important staple crops in the world, but its growth and productivity are frequently restrained by stresses such as drought, salinity and flooding. To date, many resources have been documented to investigate how wheat responds and adapts to these individual stresses during plant development and yield formation, but little attention was paid to the understandings of the internal link between different conditions, especially during the germination process, a critical stage that determines the optimal growth of wheat. In this study, we carried out the proteome profiling of the germinating seeds of a common wheat cultivar, Chinese Spring, subjected to PEG, NaCl and submergence stresses. We found that the phenylpropanoid biosynthesis and fatty acid degradation pathways were enriched as the ubiquitous stress responses, while some pathways were stress-specific, for instance, starch and sucrose metabolism against submergence. The changes in some of the altered processes were further validated by physiological and molecular approaches. Our results suggest that the overall pathway profiles concerned with the three stresses were similar, but the specific procedures and components in each process varied greatly. The altered proteins and processes can be taken as effective candidates in future breeding and agronomic modification researches.