Integrated transcriptomic and WGCNA identify drought-responsive TFs in Larix olgensis.

Global forests face increasingly severe drought events, which suppress the growth of larch. Transcription factors (TFs), acting as regulators, can increase plant stress tolerance by modulating gene expression networks. This study integrated RNA-seq, WGCNA and physiology to systematically analyze the adaptation mechanisms of Larix olgensis under drought stress. Among the 50,110 unigenes identified via RNA-seq, 1,391 unigenes were annotated as TFs. These TFs were clustered into four distinct clusters based on expression profiles. TFs within Cluster 1 exhibited significant differential expression during visible wilting of L. olgensis (72 h and 96 h). Ten TFs were selected as candidate TFs from Cluster 1 based on fold-change rank (p < 0.05). Subsequent WGCNA clustered the 50,110 unigenes into 19 co-expression modules. Notably, the firebrick4 module displayed a strong positive correlation with hydrogen peroxide (H2O2) and malondialdehyde (MDA) contents, whereas the darkolivegreen module showed a strong positive correlation with peroxidase (POD) activity. Three TFs in the firebrick4 module (TRINITY_DN13923_c0_g2, TRINITY_DN3004_c0_g1 and TRINITY_DN1230_c0_g1) and two TFs in the darkolivegreen module (TRINITY_DN1156_c1_g3 and TRINITY_DN1156_c1_g1) were identified by co-expression network analysis. The findings of this study contribute to the knowledge of drought-responsive TFs in L. olgensis, establishing a foundational resource for future functional studies and molecular breeding.