Transcriptome Analysis Reveals the Role of Plant Hormone Signal Transduction Pathways in the Drought Stress Response of Hemerocallis middendorffii

Drought stress is a significant environmental factor that can impede plant growth and ornamental quality. <i>Hemerocallis middendorffii</i>, a drought-tolerant garden plant, has attracted attention for its ornamental value and application prospects. To investigate the molecular mechanism of drought stress resistance of <i>H</i>. <i>middendorffii</i>, this study employed 20% polyethylene glycol (PEG) 6000 to simulate drought stress. Leaves and roots of <i>H</i>. <i>middendorfii</i> were subjected to 24 h treatment and followed by transcriptome sequencing. Analysis revealed 8796 and 3401 differentially expressed genes (DEGs) in leaves and roots. The major biological processes and key molecular pathways activated under drought stress in <i>H</i>. <i>middendorffii</i> were revealed by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses. The focus of this analysis was on the gene expression changes within plant hormone signal transduction pathway. Additionally, drought-associated transcription factor families such as AP2/ERF, WRKY, MYB, bHLH, NAC, and bZIP were identified among DEGs. Furthermore, potential regulatory relationships of the above transcription factors (TFs) with functional genes in the abscisic acid (ABA) and jasmonic acid (JA) signalling pathways were analysed using correlation network prediction. This research establishes the groundwork for subsequent exploration of drought-responsive gene expression and regulatory patterns in <i>H</i>. <i>middendorfii</i> and provides an importance for the systematic study of its drought-resistant molecular mechanism.