Genetic analyses of anthocyanin concentrations and intensity of red bulb color among segregating haploid progenies of onion

摘要

Higher concentrations of anthocyanins in vegetables are important for attractive appearance and may offer health benefits for consumers. The red color of onion (Allium cepa) bulbs is due primarily to the accumulation of anthocyanins. The goal of this study was to identify chromosome regions that significantly affect concentrations of anthocyanins and soluble solids in onion bulbs. Segregating haploid plants from the cross of yellow (OH1) and red (5225) inbreds were asexually propagated and bulbs were produced in replicated trials across three environments. Concentrations of soluble solids were measured at 30 days after harvest and quantitative analyses revealed a significant region on chromosome 5. Analyses using a binary model for segregation of red versus yellow bulbs revealed a significant region on chromosome 7 and two regions linked in repulsion phase on chromosome 4. These results are consistent with the complementary two-locus model previously proposed to control red versus yellow bulb colors in onion. The region on chromosome 7 mapped to the same location as the R locus, and the regions on chromosome 4 may correspond to the L and L2 loci. The intensity of red bulb color was assessed visually by a panel of evaluators and by amounts of anthocyanins [peonidin 3-glucoside and cyanidin 3-(6aEuro(3)-malonoyl-laminaribioside)] measured by high-performance liquid chromatography. Quantitative analyses using a normal model revealed significant quantitative trait loci on chromosomes 1, 4 and 8 affecting anthocyanin concentrations, and yellow onion contributed beneficial genetic variation to enhance red bulb color. Significant correlations were observed between these anthocyanin concentrations and panel scores, indicating that visual selection should be effective for increasing anthocyanin levels in onion bulbs. These selected populations may be more attractive to consumers, potentially provide health benefits from increased anthocyanin consumption, and be a source of natural colorants.