A genome-wide study of the lipoxygenase (LOX) gene family in Vigna angularis and identification of seed-specific LOX genes

Abstract

Lipoxygenase (LOX) is a multifunctional enzyme involved in flavor-associated metabolite production, plant development, and stress responses. However, the LOX gene family in adzuki bean (Vigna angularis) has not been systematically characterized. We aimed to identify and characterize in the LOX gene family in adzuki bean and investigate their potential roles in seed LOX activity. Genome-wide identification of LOX genes was performed, followed by phylogenetic, structural, and duplication analyses. Gene expression patterns were analyzed using RNA-seq and validated by qRT-PCR. LOX activity in seeds was evaluated using a colorimetric assay. We identified 24 LOX genes, including 4 9-LOX, 13 type I 13-LOX, and 7 type II 13-LOX members. Gene expansion was associated with segmental and tandem duplication. Expression analysis revealed tissue-specific patterns, with VaLOX8 and VaLOX11 highly expressed in seeds. LOX2 and LOX3 activities were detected in mature seeds, whereas LOX1 activity was absent across 32 adzuki cultivars. Based on phylogenetic, sequence alignment, and synteny analyses, VaLOX8 and VaLOX11 were found to be orthologous to GmLOX3 and GmLOX2, respectively, suggesting roles in LOX3 and LOX2 activities. This study provides foundational insights into the LOX gene family in adzuki bean.