Genome-Wide Identification and Hormone-Induced Expression Analysis of the Anthocyanidin Reductase Gene Family in Sainfoin (Onobrychis viciifolia Scop.)

Sainfoin (<i>Onobrychis viciifolia</i> Scop.) is an important legume forage. Its anthocyanidin reductase (ANR) catalyzes the conversion of anthocyanins to epicatechins. This conversion reaction is not only a key step in the biosynthesis of proanthocyanidins (PAs) but also directly influences both forage quality and stress resistance. Here, we systematically identified 67 <i>ANR</i> gene family members in autotetraploid sainfoin for the first time. Using bioinformatics approaches, we analyzed gene structure, conserved domains, motifs, and cis-regulatory elements of the identified <i>ANR</i> genes. In this study, phylogenetic analysis revealed that the <i>ANRs</i> clustered into 11 distinct clades, with genes within the same clade predominantly originating from closely related species within the same family. Significant collinearity with <i>Arabidopsis thaliana</i>, <i>Glycine max</i>, <i>Cicer arietinum</i>, and <i>Medicago truncatula</i> further revealed the conserved evolutionary path of this gene family. RT-qPCR analysis showed differential expression patterns of <i>OvANRs</i> in root, stem, and leaf tissues. For instance, <i>OvANR19</i> was significantly induced by abscisic acid (ABA) and methyl jasmonate (MeJA), with its expression upregulated by 79.7-fold and 3.8-fold in roots and by 16.2-fold and 31.3-fold in leaves. Furthermore, subcellular localization analysis confirmed that representative ANR proteins were localized in the cytoplasm. This study lays a foundation for molecular breeding aimed at enhancing stress resistance and forage quality in sainfoin.