Transcriptome and Metabolome Reveal Ferulic Acid as a Critical Phenylpropanoid for Drought Resistance in Dendrobium...

As an endemic epiphytic orchid of Hainan Island, Dendrobium sinense exhibits remarkable ecological and economic value, serving important ornamental and medicinal purposes. The combination of its epiphytic growth habit and the distinct dry season in Hainan (November-May) under the subtropical monsoon climate makes D. sinense particularly vulnerable to recurrent drought stress. Therefore, elucidating its drought tolerance mechanisms offers critical insights for both conservation strategies and stress resistance studies in D. sinense. Using polyethylene glycol (PEG)-induced drought stress, chlorophyll content decreased significantly with increasing PEG concentration, while MDA and proline content, SOD, POD CAT, and APX activity showed a significant increase. The analysis of physiological indicators indicated that plants have been subjected to drought stress. We then conducted the joint analysis of the metabolomics and transcriptomics data. Cluster analysis of differentially expressed genes and metabolites showed that drought stress markedly upregulates phenylpropanoid biosynthesis, with ferulic acid (FA) identified as a pivotal metabolite. Exogenous FA application alleviated drought-induced chlorophyll degradation in D. sinense seedlings. Heterologous expression of DsCOMT (a key FA biosynthetic gene) in Arabidopsis thaliana significantly enhanced drought survival. These results demonstrate the crucial role of FA in drought resistance and provide key insights into drought-related metabolic mechanisms.