Proteomic analysis of wheat contrasting genotypes reveals the interplay between primary metabolic and regulatory pathways in anthers under drought stress

Reproductive stage is very sensitive to various forms of environmental stresses such as drought stress. The proteomic analysis of anther during pollen development in response to drought stress was performed using a label-free quantitative shotgun proteomic technique to define the underlying molecular principles in two contrasting wheat genotypes Shiraz (susceptible) and D-10 (tolerant). Drought stress resulted in around two-fold decline in seed setting capacity and pollen viability in the Shiraz genotype compared to D-10. A Partial Least Square Discriminant Analysis (PLS-DA) of proteomic data revealed the abundance of 131 differentially abundant proteins significantly contributing in separation of drought tolerant and susceptible genotypes under normal and stress conditions. Proteins involved in cellular respiration, carbohydrate metabolism, RNA metabolism, and vesicle trafficking showed completely different responses in two genotypes. These proteins may maintain hexose pool and energy level and control regulation of transcription and transport. Furthermore, different members of functional groups such as protein biosynthesis and degradation, chromatin organization, and cytoskeleton dynamics were differentially abundant in response to stress in both genotypes which suggest their function in both genotypes to maintain minimum pollen viability/ fertility under drought stress. In conclusion, our findings revealed various metabolic and regulatory pathways underlying survival strategies required for pollen fertility and viability. 

Significance: Drought caused by global climate change decreases cereal grain productivity worldwide. Yield losses due to water stress have been reported for major small grain cereal including wheat. Our findings highlighted the importance of key proteins in wheat adaptation to drought stress at reproductive stage. The obtained data showed that differentially abundant proteins in drought tolerant wheat genotype was remarkably associated with cellular respiration, carbohydrate metabolism, RNA metabolism, and vesicle trafficking. These results revealed fundamental data to elucidate the complexity of pollen fertility and viability under drought stress condition in wheat.