Unlocking Dendrobium officinale’s drought resistance: Insights from transcriptomic analysis and enhanced drought tolerance in tomato

Dendrobium officinale is an orchid herb distinguished by its exceptional drought resistance capabilities. The remarkable drought tolerance of D. officinale stems from its structural and compositional features, including thick leaves and stems containing abundant polysaccharides and colloidal substances. Despite these adaptations, the underlying molecular mechanisms responsible for enhanced drought tolerance remain inadequately understood. This study subjected D. officinale to water restriction for periods ranging from 1 to 6 months, conducting physiological and RNA sequencing analyses to elucidate its long-term dehydration response mechanisms and identify drought-protective genes. Following 6 months of dehydration, D. officinale maintained viability, demonstrated by rapid growth resumption after merely 2 d of rehydration. Transcriptome analysis of D. officinale plants under 1-month dehydration revealed differential gene expression across various processes, predominantly in stress responses, photosynthesis, phytohormone signaling, carbon metabolism, and fructose/mannose pathways. Among these, PEROXIDASE4 (POD4) and NAC37 showed significant upregulation and were selected for further investigation of their roles in drought protection. Transgenic tomato plants overexpressing D. officinale’s POD4 and NAC37 genes exhibited superior drought tolerance compared to controls, displaying enhanced vigor, increased fruit production, higher respiration rates, elevated chlorophyll levels, and reduced oxidative damage. This research demonstrates the value of exploring underutilized species for drought-tolerance genes and identifies POD4 and NAC37 as promising candidates for improving drought tolerance through breeding programs.