A validation study by integrated analysis of physiological, biochemical, and meta-gene expression responses to drought stress in sorghum (Sorghum bicolor L.).

Sorghum (Sorghum bicolor L.) is a prominent cereal known for its high photosynthetic efficiency and biomass production, serving as a source of food, animal feed, fiber, and biofuels. This study aims to validate identified meta-genes associated with drought stress in sorghum. Two cultivars, Mansour (drought-tolerant) and Pegah (drought-susceptible), were subjected to drought stress at four levels (25%, 50%, 75%, and 100% of field capacity [FC]( During the 4-5 leaf stage in a greenhouse in 2021. The physiological and molecular responses of the sorghum samples were evaluated at 24, 48, 72, and 96 h post-treatment. The expression of five meta-genes was analyzed to validate these candidate genes related to drought stress tolerance in sorghum. Analysis of variance indicated that the main effects of drought, cultivar, and sampling time, as well as their interactions, had highly significant effects (P < 0.01) on most physiological and biochemical traits. The relative expression of the genes SORBI_3002G225100, SORBI_3003G332200, SORBI_3003G368300, SORBI_3010G081800, and SORBI_3004G293500 increased over time under drought stress. Proline levels, ion leakage, soluble sugars, and the activities of catalase, peroxidase, ascorbate peroxidase, and superoxide dismutase enzymes increased with the intensity of drought stress and over time. Conversely, the levels of chlorophyll a and b, carotenoids, RWC, leaf surface area, and protein content decreased under drought conditions. These results confirm the relevance of these genes in conferring drought stress tolerance in sorghum. This research provides new finding into the physiological processes and biochemical activities, alongside the validation of meta-gene expression involved in drought stress, further advancing our understanding of molecular mechanisms of the reaction of sorghum to drought stress.