Genome-wide association analysis and gene mining of flavonoids in Xanthoceras sorbifolia

Xanthoceras sorbifolia is a unique woody oilseed tree in China, and its leaves are rich in flavonoids, which are involved in plant growth, development and defense. However, the mining of flavonoid synthesis-related genes in Xanthoceras sorbifolia leaves is lacking. In this study, 226 leaves of Xanthoceras sorbifolia from eight provinces in the key distribution areas were measured for flavonoid content, and the differences in flavonoid content of Xanthoceras sorbifolia were analysed to screen out excellent seed sources and six excellent single plants with higher flavonoid content. Genome-wide association analysis (GWAS) was used to identify genes controlling the synthesis of flavonoids, and 62 significant Single nucleotide polymorphism (SNP) sites were identified, which were closely associated with 8 traits, and a total of 11 genes coding for proteins. We found that these genes mainly encode proteins such as WPP domain-associated protein (WAP) (Fragment), Protein pleiotropic regulatory locus 1 (PRL1) and Phosphomevalonate kinase, peroxisomal (PMK), etc. We found that these proteins may directly or indirectly affect the synthesis of flavonoids, which will provide a data base for molecular breeding and genetic improvement of Xanthoceras sorbifolia.