Dehydration-induced proteomic landscape of mitochondria in chickpea reveals large-scale coordination of key biological processes.

Mitochondria play crucial roles in regulating multiple biological processes particularly electron transfer and energy metabolism in eukaryotic cells. Exposure to water-deficit or dehydration may affect mitochondrial function, and dehydration response may dictate cell fate decisions. iTRAQ-based quantitative proteome of a winter legume, chickpea, demonstrated the central metabolic alterations in mitochondria, presumably involved in dehydration adaptation. Three-week-old chickpea seedlings were subjected to progressive dehydration and the magnitude of dehydration-induced compensatory physiological responses was monitored in terms of physicochemical characteristics and mitochondrial architecture. The proteomics analysis led to the identification of 40 dehydration-responsive proteins whose expressions were significantly modulated by dehydration. The differentially expressed proteins were implicated in different metabolic processes, with obvious functional tendencies toward purine-thiamine metabolic network, pathways of carbon fixation and oxidative phosphorylation. The linearity of dehydration-induced proteome alteration was examined with transcript abundance of randomly selected candidates under multivariate stress conditions. The differentially regulated proteins were validated through sequence analysis. An extensive sequence based localization prediction revealed >62.5% proteins to be mitochondrial resident by, at least, one prediction algorithm. The results altogether provide intriguing insights into the dehydration-responsive metabolic pathways and useful clues to identify crucial proteins linked to stress tolerance.

BIOLOGICAL SIGNIFICANCE: Investigation on plant mitochondrial proteome is of significance because it would allow a better understanding of mitochondrial function in plant adaptation to stress. Mitochondria are the unique organelles, which play a crucial role in energy metabolism and cellular homeostasis, particularly when exposed to stress conditions. Chickpea is one of the cultivated winter legumes, which enriches soil nitrogen and has very low water footprint and thus contributes to fortification of sustainable agriculture. We therefore examined the dehydration-responsive mitochondrial proteome landscape of chickpea and queried whether molecular interplay of mitochondrial proteins modulate dehydration tolerance. A total of 40 dehydration-induced mitochondrial proteins were identified, predicted to be involved in key metabolic processes. Our future efforts would focus on understanding both posttranslational modification and processing for comprehensive characterization of mitochondrial protein function. This approach will facilitate mining of more biomarkers linked to the tolerance trait and contribute to crop adaptation to climate change.