Genome-wide identification of the DFR gene family in Dracaena cambodiana and its expression analysis under wound stress

Dracaena cambodiana Pierre ex Gagnep. is divided into two distinct groups: the Yunnan clade with soft leaves (D. cambodiana A) and the Hainan clade with hard leaves (D. cambodiana B). This species is the key plant source of dragon’s blood, a well-known traditional Chinese medicine derived from the defensive metabolites of Dracaena species, with flavonoids as its major bioactive components. Dihydroflavonol 4-reductase (DFR) plays a pivotal role in flavonoid biosynthetic pathway. In this study, we identified 19 DFR genes (designated as DcDFRs) from the reference genome of D. cambodiana, which are distributed across six chromosomes and phylogenetically classified into four subfamilies. Comprehensive analyses of their chromosomal localization, sequence homology, gene structure, and phylogenetic relationships revealed two distinct tandemly duplicated gene clusters (TDGCs), designated as TDGCs-1 and TDGCs-2. Notably, TDGCs-1, comprising DcDFR1–DcDFR5 and localized on chromosome 5, exhibits conserved tissue-specific co-expression patterns and coordinated transcriptional responses to wound stress across two distinct D. cambodiana accessions (D. cambodiana A and D. cambodiana B). Its expression levels are positively correlated with both the duration of stress induction and flavonoid accumulation, suggesting a critical role in flavonoid metabolism and wound defense responses. Unlike TDGCs-1, TDGCs-2 does not show typical co-expression patterns under wound stress in D. cambodiana A, which implies that the two tandemly duplicated gene clusters have both overlapping and distinct biological functions. This study reveals the secondary metabolic pathways triggered by particular environmental stresses and provides a theoretical foundation for future investigations into the artificial induction technology of dragon’s blood.