Abstract

Cinnamyl alcohol dehydrogenase (CAD) is essential for the synthesis of plant lignin precursors and the response to various abiotic stresses. In this study, we identified 17OjCADgenes distributed across the genome ofOenanthe javanica. The members of theOjCADgene family were unevenly distributed on six chromosomes, and subcellular localization was predicted in the cytoplasm. Based on phylogenetic analysis, these OjCADs were divided into four groups. Members in group I, containingOjCAD15andOjCAD17,are the core regulatory genes involved in lignin synthesis. The conserved region of protein sequence contained two Zn2+binding motifs and NADP(H) cofactor-binding motifs, which belonged to the typical CAD protein. Collinearity analysis showed that there were two tandem repeats and three fragment repeats inOjCADgene, and there were three pairs of collinear gene pairs. Acis-acting element component analysis displayed that mostCADgenes were involved in mediating responses to light, stress, and plant hormones. Following GA3 treatment, the lignin content in petioles and leaf blades of water dropwort initially increased significantly, leading to a decline in palatability. In contrast, lignin content decreased markedly after uniconazole treatment. Anatomical structure analysis and UV fluorescence in the petiole also confirmed the results. In the expression profiling analysis and RT-qPCR results, the expression trend ofOjCAD16in leaves was consistent with the transcriptional expression profile. Following GA3 treatment, the gene expression changes in petioles for four genes (OjCAD13,OjCAD15,OjCAD16, andOjCAD17) aligned with the trends in lignin content, suggesting they may positively regulate lignin synthesis inO. javanica. These findings highlighted the multifunctional role of theCADgene family in regulating lignin in water dropwort under gibberellin action, providing a potential basis for improving flavor quality by modulating lignin content.