Comparative transcriptome analysis to reveal key drought stress-responsive genes in sorghum (Sorghum bicolor (L.) Moench).

Flowering pathways are accelerated for the rapid production of flowers and seeds in response to drought in certain varieties of sorghum (Sorghum bicolor (L.) Moench). The objective of the present study was to identify potential drought-responsive genes that affect flowering time in sorghum under drought stress. Sorghum germplasm accessions representing early-, intermediate-, and late-flowering groups were selected, and drought stress was applied to 25-day-old seedlings in the drought-stressed (DS) group by withdrawing water, while those in the control (WW) group were well watered. At anthesis stage, flag leaf tissues were harvested, and total RNA was separately isolated from the samples. Transcription profiles consisting of 60 base pairs and paired-end reads from the total RNA of each sample were explored via the Illumina Genome Analyser deep sequencing method. An average of 66,059,932 clean reads were mapped. Among the 10,468 DEGs, 126 genes were upregulated, and 61 genes were downregulated in all comparisons. Pathway enrichment analysis revealed that the de novo purine biosynthesis and lipoate biosynthesis pathways and the Wnt signalling pathway affect sorghum genes that are differentially expressed in response to drought. Transcriptome level differences among the early-, intermediate- and late-flowering groups of sorghum under WW and DS conditions were explored efficiently in the present study via RNA sequence analysis tools. The functional characterization of the DEGs and pathways identified here could reveal a sophisticated and highly coordinated survival strategy for sorghum under drought. Candidate genes and pathways that might be used to improve drought tolerance in sorghum were identified. The findings of the present study could lead to new targets for enhancing drought stress tolerance in sorghum and other crops.