Seed priming with NaCl boosted the glutathione-ascorbate pool to facilitate photosystem-II function and maintain starch in NaCl-primed chickpea under salt stress

Abstract

Seed priming with NaCl improved the tissue tolerance nature in moderately salt-tolerant cultivar Anuradha under salt stress. Is an improved tissue tolerance in primed chickpea seedlings supplemented with a boosted antioxidant response? To investigate, a seed priming experiment with sub-lethal salt concentration (50 mM NaCl) was performed with chickpea cv. Anuradha. The morphological, physiological, biochemical, and molecular responses associated with reactive oxygen species, antioxidant activities, photosystem-II (PS-II) efficiency, and starch-sugar metabolism were studied at 150 mM NaCl in hydroponically grown nonprimed and primed seedlings. Primed chickpea seedlings maintained high biomass compared to nonprimed seedlings under stress. High level of reduced ascorbate, glutathione contents and higher activity of glutathione reductase and dehydroascorbate reductase suggested that primed seedling improved the antioxidant response, thus able to maintain low hydrogen peroxide under stress. High photosystem-II (PS-II) efficiency and high electron transport rate of PS-II in primed chickpea seedlings under stress suggested that primed seedlings are able to maintain PS-II function under stress, thus able to retain the flow of electrons for PS-II. A high starch content and low alpha amylase gene expression in primed seedlings suggested that NaCl priming could utilize the reserve food compounds slowly. Overall, this study uncovers that seed priming with NaCl boosted the antioxidant responses in primed chickpea seedlings to stabilize the PS-II function and facilitates the flow of electrons for PS-II, indispensable for energy generation, thus reducing the need of starch degradation and maintaining better starch-sugar equilibrium in primed seedlings.