Furanocoumarins (FCs) are a group of related plant defense metabolites occurring in several plant families, including some species in the genus citrus, such as grapefruit and pummelo. FCs function as toxins against pa...Furanocoumarins (FCs) are a group of related plant defense metabolites occurring in several plant families, including some species in the genus citrus, such as grapefruit and pummelo. FCs function as toxins against pathogens, insects and other plant pests and some are toxic to humans at high levels. Although the levels of FCs in grapefruits are non-toxic to humans, they inhibit the intestinal enzyme CYP3A, thus preventing degradation of medicines, such as statins, and causing dangerous overdose effects. This overdosing can cause devastating side effects, ranging from stomach bleeding to kidney problems, muscle aches and irregular heartbeats. In the present study, we utilize LC/MS to characterize the levels of FCs pathway intermediates and end products in twelve citrus cultivars, including mandarin (Citrus reticulata), orange [Citrus sinensis (L.) Osbeck], Pummelo [Citrus maxima (Burm.) Merr.], grapefruit (Citrus paradisi Macf.), and two newly selected grapefruit like varieties [(Citrus reticulate) X [Citrus maxima (Burm.) Merr]. The orange and mandarin varieties do not contain FCs or FCs precursor compounds suggesting that this biosynthetic pathway is absent or inactive in mandarins and oranges and therefore a good genetic source for null alleles to FCs biosynthesis. We report the selection and characterization of two new low FCs and seedless grapefruit-like varieties, “Aliza” and “Coocki”, developed by a cross between pummelo and mandarin. Fruits of these varieties resemble grapefruit and contain high levels of the flavanone naringin, typical of grapefruit, but contain only trace amounts of FCs (based on LCMS analysis). Based on the variability of FCs content and inheritance in citrus species, the results suggest that future development of new low-FCs grapefruit varieties is an achievable objective.展开更多
Gamma irradiation mutagenesis is a technique commonly used to induce seedlessness in citrus fruits. We compared fruit quality traits of eight different seeded mandarin varieties within the Israeli citrus breeding coll...Gamma irradiation mutagenesis is a technique commonly used to induce seedlessness in citrus fruits. We compared fruit quality traits of eight different seeded mandarin varieties within the Israeli citrus breeding collection with those of their corresponding gamma-irradiated low-seeded mutants. The mandarin varieties compared were: “Rishon” with “Kedem”;“Michal” with irradiated “Michal”;“Merav” with “Meravit”;“Vered” with “Vardit”;“Ora” with “Or”;“Murcott” with “Mor”;“Shani” with irradiated “Shani”;“King” with irradiated “King”. Mutational breeding by gamma irradiation reduced average fruit seed number by 70% - 92%. Furthermore, mutational breeding by gamma irradiation delayed ripening of the early-season mandarin varieties “Rishon” and “Michal” by 8 - 13 days, but did not delay ripening of most mid- and late-season varieties. Gamma-irradia- tion mutagenesis also reduced fruit weight of seven of the eight tested low-seeded varieties by 6 - 41 g per fruit. Gamma-irradiation mutagenesis had variable effects on biochemical composition and nutritional quality, in that some irradiated clones presented no changes whereas other had either higher or lower levels of juice total soluble solids, acidity, vitamin C and total antioxidant activity. Finally, sensory evaluations by a trained panel revealed that the flavor of most of the low-seeded, gamma-irradiated varieties was slightly or significantly preferable to that of unirradiated varieties.展开更多
文摘Furanocoumarins (FCs) are a group of related plant defense metabolites occurring in several plant families, including some species in the genus citrus, such as grapefruit and pummelo. FCs function as toxins against pathogens, insects and other plant pests and some are toxic to humans at high levels. Although the levels of FCs in grapefruits are non-toxic to humans, they inhibit the intestinal enzyme CYP3A, thus preventing degradation of medicines, such as statins, and causing dangerous overdose effects. This overdosing can cause devastating side effects, ranging from stomach bleeding to kidney problems, muscle aches and irregular heartbeats. In the present study, we utilize LC/MS to characterize the levels of FCs pathway intermediates and end products in twelve citrus cultivars, including mandarin (Citrus reticulata), orange [Citrus sinensis (L.) Osbeck], Pummelo [Citrus maxima (Burm.) Merr.], grapefruit (Citrus paradisi Macf.), and two newly selected grapefruit like varieties [(Citrus reticulate) X [Citrus maxima (Burm.) Merr]. The orange and mandarin varieties do not contain FCs or FCs precursor compounds suggesting that this biosynthetic pathway is absent or inactive in mandarins and oranges and therefore a good genetic source for null alleles to FCs biosynthesis. We report the selection and characterization of two new low FCs and seedless grapefruit-like varieties, “Aliza” and “Coocki”, developed by a cross between pummelo and mandarin. Fruits of these varieties resemble grapefruit and contain high levels of the flavanone naringin, typical of grapefruit, but contain only trace amounts of FCs (based on LCMS analysis). Based on the variability of FCs content and inheritance in citrus species, the results suggest that future development of new low-FCs grapefruit varieties is an achievable objective.
文摘Gamma irradiation mutagenesis is a technique commonly used to induce seedlessness in citrus fruits. We compared fruit quality traits of eight different seeded mandarin varieties within the Israeli citrus breeding collection with those of their corresponding gamma-irradiated low-seeded mutants. The mandarin varieties compared were: “Rishon” with “Kedem”;“Michal” with irradiated “Michal”;“Merav” with “Meravit”;“Vered” with “Vardit”;“Ora” with “Or”;“Murcott” with “Mor”;“Shani” with irradiated “Shani”;“King” with irradiated “King”. Mutational breeding by gamma irradiation reduced average fruit seed number by 70% - 92%. Furthermore, mutational breeding by gamma irradiation delayed ripening of the early-season mandarin varieties “Rishon” and “Michal” by 8 - 13 days, but did not delay ripening of most mid- and late-season varieties. Gamma-irradia- tion mutagenesis also reduced fruit weight of seven of the eight tested low-seeded varieties by 6 - 41 g per fruit. Gamma-irradiation mutagenesis had variable effects on biochemical composition and nutritional quality, in that some irradiated clones presented no changes whereas other had either higher or lower levels of juice total soluble solids, acidity, vitamin C and total antioxidant activity. Finally, sensory evaluations by a trained panel revealed that the flavor of most of the low-seeded, gamma-irradiated varieties was slightly or significantly preferable to that of unirradiated varieties.
