Transcriptome and co-expression network analyses reveal the mechanisms of early response to drought stress in oat leaves

Abstract Drought, as major abiotic stress, primarily restricts the production of oat (Avena sativa) around the world. With the aim of elucidating oat leaves’ early response to drought stress, this study focused on examining the contents of malondialdehyde (MDA), soluble sugar (SS), and proline (Pro) and the transcriptome of oat leaves under 0, 12, 24, 36, and 48 h of drought treatment, revealing that the content of MDA increased with drought duration, whereas the contents of SS and Pro reached their maximum at 24 h of treatment, with a total between 0 h of treatment and the other groups. Differentially expressed genes (DEGs) presented significant enrichment in the phenylpropanoid biosynthetic pathway, flavonoid biosynthetic pathway, galactose metabolism, and glutathione metabolism. The biological changes caused by drought stress resulted in the obvious activation of antioxidase genes. The sugar and flavonoid biosynthetic genes were studied based on the detailed temporal patterns of expression of four major metabolic pathways. Additionally, 14 candidate hub genes, such as the genes that encoded galactinol synthase, serine/threonine-protein kinase, and 1-aminocyclopropane-1-carboxylate oxidase, were identified by virtue of weighted gene co-expression network analysis. Differential transcription factor (TF) analysis showed that NAM, ATAF1/2, CUC2 (NAC), Heat Shock (HS), Trihelix, TEOSINTE BRANCHED1/CYCLOIDEA/PCF (TCP), and other 11 TF families were closely related to drought stress. These findings help us understand the early responses of oat to drought stress from new perspectives and can guide further research.