Hydrogen sulfide improves plant drought tolerance by regulating the homeostasis of reactive oxygen species

Drought stress severely impedes plant growth and development, and hydrogen sulfide (H₂S) actively participates in plant drought responses. To comprehensively understand the regulatory mechanism of H₂S in drought tolerance, an RNA-Seq analysis was conducted to investigate the drought-responsive genes modulated by H₂S. The study identified 3,043 differentially expressed genes (DEGs) that displayed dual responses to ‘drought stress-H₂S signaling’. Subsequent enrichment analyses using Gene Ontology and the Kyoto Encyclopedia of Genes and Genomes pathways identified the enrichment of several DEGs associated with ‘ribosome biogenesis’, ‘hormone response’, ‘drought transcription factors’, and ‘antioxidant properties’. DEGs closely linked to ribosome biogenesis yield products, such as ribonucleases, nucleolar proteins, and others, which play crucial roles in ribosome biogenesis. Among the eight hormone classes, abscisic acid acts as a positive regulator in response to H₂S signaling. H₂S mainly enhanced plant drought resistance by regulating three key factors in the double-negative regulatory signal pathway of abscisic acid. Under drought stress, five types of transcription factor families, basic helix-loop-helix, NAM-ATAF_1/2-CUC_1/2, myeloblastosis, MYB_related, and ethylene responsive factor, were actively regulated by H₂S signals. In addition, H₂S enhanced the cell’s ability to remove reactive oxygen species by increasing superoxide dismutase and peroxidase activities, as well as glutathione peroxidase expression. In conclusion, the H₂S signals improved plant drought resistance through the regulation of ribosome biogenesis, plant hormone signal transduction, transcription factors, and antioxidant capacity. This research provides an important reference that aids in our comprehensive understanding of plant H₂S-related drought resistance mechanisms.