NUTRITIONALLY-ENHANCED APPLES: MARKERS FOR MOLECULAR BREEDING FOR FRUIT VITAMIN C CONCENTRATIONS IN APPLE
Vitamin C (L-ascorbic acid, AsA) is a central component of plant metabolism and plant adaptive defence responses, but it is also widely recognised as having a range of beneficial health properties for the consumer. There is thus much interest in understanding homeostasis of this ubiquitous antioxidant. To help identify the genetic factors underlying the regulation of fruit AsA concentration, quantitative trait loci (QTL) studies were carried out in an F1 progeny derived from a cross between the apple (Malus × domestica Borkh.) cultivars Telamon and Braeburn over 3 separate years in Belgium. Four, stable QTL clusters, collectively explaining up to 60% of the total population variability in fruit AsA concentration were identified. SNP-based mapping of a range of AsA metabolic gene orthologues identified co-locations between paralogues of GDP-L-galactose phosphorylase (GGP) and stable QTL clusters. Importantly, the allelic variants of these paralogues were consistently associated with high/low fruit AsA concentration within the mapping population. Interestingly, we also found stable co-locations between an orthologue of dehydroascorbate reductase (DHAR), which is involved in AsA recycling and major QTL for flesh browning in the Telamon parent, supporting a role for AsA redox status in susceptibility to browning.
Mellidou, I., Keulemans, J., Davey, M.W., Chagné, D., Gardiner, S.E. and Laing, W. (2014). NUTRITIONALLY-ENHANCED APPLES: MARKERS FOR MOLECULAR BREEDING FOR FRUIT VITAMIN C CONCENTRATIONS IN APPLE. Acta Hortic. 1048, 163-170
Malus × domestica, vitamin C, QTL, candidate gene mapping, flesh browning, molecular markers, nutritional enhancement