ISHS Acta Horticulturae 770: XXVII International Horticultural Congress - IHC2006: International Symposium on Cultivation and Utilization of Asian, Sub-tropical, and Underutilized Horticultural Crops
MOLECULAR APPROACHES TO CHARACTERIZING AND IMPROVING BULB COMPOSITION IN ONION |
| Authors: | J. McCallum, M. Shigyo, M.J. Havey, M.T. McManus |
| Keywords: | onion, genetic mapping, markers, carbohydrate, flavour, sulfur |
| Abstract:
Onion bulb composition varies widely, both within and between varieties. Development of Allium gene sequence and mapping resources has enabled dissection of bulb composition traits through genetic analysis and physiological studies. The collaborative use of complementary genetic stocks has proved critical to this progress. Mutation scanning of the 5’ regions of genes has proved the most robust source of portable markers to date. Both marker and QTL studies to date confirmed high levels of heterozygosity within bulb onion. The most surprising finding to date is that a single genetic locus, Frc, conditions the majority of the variation in reducing sugar and fructan contents between sweet and storage onion types. Heterozygosity at this dominant locus could underlie substantial within-population variation in bulb composition. Another well-supported locus conditions variation in dry matter and pleiotropic effects on pungency. Biochemical and genetic studies have supported earlier suggestions that differences in S assimilation underlie some genetic variation in pungency. | |
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