Effect of Poncirus trifoliata on the chemical composition of fruits in pedigrees of Citrus scion hybrids

Abstract

Citrus breeders have made numerous hybridizations that included Poncirus trifoliata L.Raf. (P. trifoliata), a relative of the genus Citrus, in their pedigree to produce hybrids that are cold- and disease-resistant. Initial hybrids of Citrus × P. trifoliata typically produce fruit that have unacceptable flavor, but more advanced hybrids with greater proportions of Citrus in their pedigrees have various degrees of off-flavor and taste. This study reports the volatile constituents, as well as nonvolatile limonoids and flavonoids, in the juice of six Citrus hybrids containing P. trifoliata in their pedigrees, compared to two hybrids derived solely from Citrus. Secondary metabolite profiles reflected the complex genetic backgrounds of those hybrids. Hybrids 6_23−20 and US 119 had juice composition most similar to that of P. trifoliata, with more volatiles, and in particular, more esters and sesquiterpenes with higher amounts in total. Furthermore, hesperidin concentration in US 119 was low (10 μg g−1) in comparison with other hybrids (125−326 μg g−1) while concentrations of narirutin and isosakuranetin-7-O-rutinoside were unusually high (135−211 μg g−1 and 304−182 μg g−1, respectively) in comparison with the other hybrids (5−60 μg g−1 and 10−75 μg g−1, respectively), which is in agreement with the composition of pure P. trifoliata. Juice of P. trifoliata derived hybrids 5−18-24, 5−18-31, 1−76-100, and 1−77-105 presented secondary metabolite compositions closer to those of pure Citrus hybrids. Based on volatiles, limonoids, and flavonoid profiles, we conclude that it is possible to generate advanced Citrus hybrids including P. trifoliata in their pedigrees that approach the quality of common Citrus types.