Transcriptome profiling of Anoectochilus roxburghii L. reveals spermidine-mediated response to drought stress

• The Anoectochilus roxburghii L. are famous for its medicinal use in traditional Chinese medicine. • Polyamines has been shown to ameliorate drought tolerance; however, the mechanism remains poorly studied. • Leaf and root tissues under drought and low spermidine treatment, (LSL vs LSR) was found to exhibit the highest number of differentially expressed genes (DEGs). • Genes such as PAL1, HPPR, S3 and PBP involved in Phenylpropanoid biosynthesis, starch metabolism, and plant hormone signal transduction pathways were found upregulated. The jewel orchid ( Anoectochilus roxburghii L. ) plants famous for its medicinal use in traditional Chinese medicine, exhibits distinctive qualities. Drought severely affects the growth and development pattern of A. roxburghii , leading to a notable decline in physiological and biochemical processes entailing reduced recovery of medicinally active compounds. Polyamines have been shown to ameliorate drought tolerance; however, the mechanism remains poorly studied. Therefore, the objective of this study was to evaluate transcriptomic changes of jewel orchid plants in response to drought and exogenous spermidine application employing RNA sequencing. The comparative transcriptomic analysis revealed significant changes in differentially expressed genes (DEGs) across all tissues. Gene Ontology (GO) and enrichment analysis were employed to explain biological processes and the transcript's relative abundance. Out of all tissue and treatment combinations, leaf and root tissues under drought and low spermidine treatment, (LSL vs LSR) were found to exhibit the highest number of differentially expressed genes (DEGs). Arrays of enriched transcripts due to drought and spermidine treatment were associated with the molecular function of binding and catalytic activity, the biological mechanism of cellular and metabolic processes, cellular components, cell and cell parts. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that genetic information processing and environmental information processing signal transduction were important pathways in the stress signaling cascade associated with drought tolerance. Genes such as PAL1, HPPR, S3, and PBP involved in Phenylpropanoid biosynthesis, starch metabolism, and plant hormone signal transduction pathways were found upregulated. High expression of plant hormone (ABA) dependent transcription factors and plant hormone signal transduction pathways were found to be interesting results of the current study. Moreover, qRT-PCR results further confirmed the RNA-seq results. This study provides the first report of transcriptomic data for A. roxburghii plants under drought stress and exogenous spermidine application. These findings, offer new perspectives and could be beneficial for elucidating the underlying molecular mechanisms of spermidine treatment that contribute to drought tolerance in A. roxburghii .