Unraveling the Complex Physiological, Biochemical, and Transcriptomic Responses of Pea Sprouts to Salinity Stress

Background: The escalating global salinization poses a significant threat to agricultural productivity, necessitating a thorough understanding of plant responses to high salinity. Pea sprouts (Pisum sativum), a nutrient-rich crop increasingly cultivated in salinized regions, serve as an ideal model for such investigations due to their rapid growth cycle and documented sensitivity to ionic stress. Methods: In order to understand the response of pea sprouts in physiological regulation, redox-metabolic adjustments, and transcriptome reprogramming under salt stress, we investigated the effects of high salt concentrations on the ascorbic acid–glutathione cycle, endogenous hormone levels, metabolite profiles, and gene expression patterns in it. Results: Our findings reveal early-phase antioxidant/hormonal adjustments, mid-phase metabolic shifts, and late-phase transcriptomic reprogramming of pea sprouts under salt conditions. In addition, a biphasic response in the ascorbic acid cycle was found, with initial increases in enzyme activities followed by a decline, suggesting a temporary enhancement of antioxidant defenses. Hormonal profiling indicated a significant increase in abscisic acid (ABA) and jasmonic acid (JA), paralleled by a decrease in indole acetic acid (IAA) and dihydrozeatin (DZ), underscoring the role of hormonal regulation in stress adaptation. Metabolomic analysis uncovered salt-induced perturbations in sugars, amino acids, and organic acids, reflecting the metabolic reconfiguration necessary for osmotic adjustment and energy reallocation. Transcriptomic analysis identified 6219 differentially expressed genes (DEGs), with a focus on photosynthesis, hormone signaling, and stress-responsive pathways, providing insights into the molecular underpinnings of salt tolerance. Conclusions: This comprehensive study offers novel insights into the complex mechanisms employed by pea sprouts to combat salinity stress, contributing to the understanding of plant salt tolerance and potentially guiding the development of salt-resistant crop varieties.