QTL mapping of flavanone glycoside accumulation in citrus

Flavanone-O-glycosides, flavone-O/C-glycosides, and their derivatives are some of the most abundant flavonoids in citrus fruits. They are attracting attention not only as health functional components, but also for their effects on the taste of fruit, such as bitterness. Elucidating the mechanism of their accumulation will provide useful information for citrus breeding programs targeting flavor and health functional components. In this study, flavanone glycoside (narirutin, naringin, hesperidin, and neohesperidin) accumulation in the leaves of the Hanayu (Citrus hanayu) × ‘Katsuyama kuganii’ shiikuwasha (Citrus depressa) F1 population was determined by high-performance liquid chromatography (HPLC), and quantitative trait loci (QTLs) for the accumulation of each component were mapped onto a linkage map constructed with SNPs between Hanayu and ‘Katsuyama kuganii’ genotyped by a high-resolution melting curve (HRM) method. QTLs for hesperidin and neohesperidin accumulation were mapped in linkage group (LG) 9, whereas a QTL for hesperidin was detected in LG 4. The QTL region in LG 9 would determine which flavanone glycosides accumulate in citrus, whereas the QTL region of LG 4 might control the overall amount of hesperetin glycosides. Amino acid substitutions in a putative glycosyltransferase gene present in the QTL region on LG 9 were correlated with neohesperidin accumulation. This study will provide useful information for the breeding of new citrus cultivars with health functional components and regulated bitterness.