Objective This study investigated the physiological metabolisms and gene expression patterns of sorghum seedlings under different durations of drought stress, aiming to identify drought-resistant genes in sorghum, and exploring the molecular response mechanisms of sorghum to drought stress.

Methods Using seedlings of the drought-tolerant variety Tx625B as the experimental material, we simulated drought stress during the seedling stage by applying 25% PEG-6000, measured the physiological indices and nutrient content of the leaves at 0 h, 12 h, and 24 h after the treatment. Subsequently, we utilized transcriptome sequencing and bioinformatics techniques to analyze the gene expression profiles of the leaves, aiming to uncover the biological functions and major metabolic pathways of differentially expressed genes (DEGs). This process facilitated the screening of DEGs associated with drought resistance.

Result Under different durations of drought stress, drought-resistant materials consistently maintain high peroxidase and catalase activities, as well as strong free radical scavenging capabilities. This effectively eliminates excess reactive oxygen species and hydrogen peroxide within the plant, thereby reducing the damage caused by external stress.Drought stress induces changes in the nitrogen, phosphorus, and potassium content of drought-resistant materials, with a more pronounced effect on nitrogen content. A total of 17396 drought responsive genes were detected through sequencing and alignment of three comparison groups: 0hvs12h, 0hvs24h, and 12hvs24h, including 8,253 upregulated genes and 9,143 downregulated genes. After analyzing the functions of the common differentially expressed genes, we identified several categories of genes that play crucial roles in the drought response during the seedling stage of sorghum: peroxidase, chlorophyll a-b binding proteins, photosystem proteins, and other chloroplast-related enzymes and protein-coding genes.Through enrichment analysis of differentially expressed genes GO and KEGG, it was found that drought stress has a significant impact on amino acid metabolism, secondary metabolite biosynthesis, carbohydrate and lipid metabolism, and plant signal transduction in sorghum seedlings. Differentially expressed genes are significantly enriched in metabolic pathways such as photosynthesis, dark response in photosynthetic organisms, and carbohydrate metabolism.

Conclusion The drought resistance regulation process of sorghum involves the coordinated interaction of multiple biological processes, which improves drought resistance by regulating photosynthetic rate and soluble sugar accumulation; The enrichment of differentially expressed genes in the amino acid metabolism pathway, photosynthesis pathway, and sugar metabolism pathway is an important reason for the strong drought resistance regulation ability of sorghum drought resistant varieties.