Ma Q, Wang R, He F, Wan W, Liu X, Zhang J, Li K, Ren M
Globally, drought has emerged as a significant limitation for agricultural development. Therefore, the development of drought-resistant crops is crucial for ensuring agricultural progress. Sorghum (Sorghum bicolor (L.) Moench) is an important bioenergy crop with excellent drought tolerance; however, its mechanisms respond to various-duration drought stress remain gap. Here, the physiological and transcriptomic responses of drought-tolerant sorghum to various-duration drought stress simulated by 200 g/L PEG-6000 were investigated. Sorghum seedlings were subjected to 0 h (CK, A), 24 h (B), 48 h (C), 120 h (D), and 168 h (E) of drought stress. The results showed that B, C, D, and E inhibited leaf water and chlorophyll content but promoted superoxide dismutase and peroxidase activities as well as malondialdehyde and proline accumulation. Transcriptome analysis detected 1,841, 1,170, 1,808, and 2,392 differentially expressed genes (DEGs) in A_vs._B, A_vs._C, A_vs._D, and A_vs._E, respectively; these DEGs were involved in photosynthesis, plant hormone signal transduction (PHST), and starch and sucrose metabolism (SSM). Weighted Gene Co-expression Network Analysis (WGCNA) identified two key modules annotated to the PHST and SSM pathways. A total of 140 and 98 DEGs were identified within PHST and SSM pathways, respectively. Notably, the coding gene Sobic.002G116000, associated with granule-bound starch synthase, was not significantly affected by short-term drought stress. Furthermore, 20 hub genes were selected through WGCNA, with Sobic.001G308100, Sobic.002G334500, and Sobic.002G202700 identified as particularly key hub genes. Collectively, these 258 genes, especially the aforementioned four, may serve as potential candidates for the molecular breeding of drought-tolerant sorghum. These findings would provide valuable insights into the molecular breeding of drought-resistant crops and contribute to sustainable agricultural development in the context of global warming.