Transcripts and ABA-dependent signaling in response to drought stress in Hippophae rhamnoides L

Key message This study revealed the ABA-dependent signaling pathway and flavonoid synthesis pathway of sea buckthorn under drought conditions from plant physiology and gene expression levels. As climate changes and temperatures rise, sea buckthorn (Hippophae rhamnoides L.) is increasingly exposed to numerous challenges, particularly aridity. In this study, the leaves of sea buckthorn were harvested from plants in drought-recovery cycles and selected for RNA sequencing to uncover the underlying genetic basis of drought stress response through physiological and biochemical analyses. The results revealed that drought conditions significantly (p < 0.05) decreased leaf water potential, net photosynthetic rate, and stomatal conductance, Abscisic acid (ABA) and flavone content significantly (p < 0.05) increased under drought conditions and recovered after rehydration. Compared with the control and recovery irrigation conditions, respectively, 7734 and 7338 genes were differentially expressed under drought stress. Major differentially expressed genes involved in ABA-dependent signaling and flavonoid biosynthesis pathways were identified. Six hub genes of the co-expression network were blasted against the Drought Stress Gene Database and were found to have direct relationships with 25 genes there were related to cellular responses to stimuli. Five hub genes and seven drought transcription factors were validated by RT-qPCR. This study elucidated the molecular mechanism of the ABA-dependent signaling pathway that affects stomatal closure and flavonoid biosynthesis in antioxidant systems under drought conditions in sea buckthorn. The identified six hub genes will serve as a valuable resource and provide essential information for improving sea buckthorn tolerance to drought conditions.