J. Palmer, L. Lozano, D. Chagné, R. Volz, K. Lin-Wang, J. Bonany, D. Micheletti, M. Troggio, A. White, S. Kumar, A.C. Allan, I. Iglesias
The biosynthesis of anthocyanins in many plant species is affected by environ-mental conditions. In apple fruit, skin anthocyanin contents are lower under hot climate conditions. We have examined anthocyanin accumulation in maturing ‘Royal Gala’ apples grown under temperate and hot conditions. Orchard-based apple heating to temperatures comparable to hot climates was performed and found to cause fast fruit colour loss and a reduction in anthocyanin content. Lower rates of biosynthesis are suggested, as a coordinative down-regulation of gene expression of the genes encoding the anthocyanin biosynthetic pathway occurs in hot conditions. In addition, the expression of the genes encoding the transcriptional activation complex is also reduced. Heating fruit rapidly reduced expression of apple anthocyanin-related genes, which correlated with a reduction in expression of the R2R3 MYB transcription factor (MYB10/MYB1) responsible for elevating apple colour.
A genetic mapping strategy was used to identify loci associated with the expression of red skin colour under high temperatures. A population of apple seedlings was phenotyped for skin colour and anthocyanin content and then genotyped using a panel of SNP markers spanning the entire apple genome. Two markers were associated with red skin colour on linkage groups 9 and 17, including a marker located close to MYB10 (LG 9). We propose that temperature-induced down-regulation of fruit anthocyanin biosynthesis is primarily due to down-regulation of the anthocyanin regulatory complex, and that the genes encoding the complex have become useful loci for the development of marker assisted breeding of new apple cultivars tolerant of warm conditions.
Palmer, J., Lozano, L., Chagné, D., Volz, R., Lin-Wang, K., Bonany, J., Micheletti, D., Troggio, M., White, A., Kumar, S., Allan, A.C. and Iglesias, I. (2012). PHYSIOLOGICAL, MOLECULAR AND GENETIC CONTROL OF APPLE SKIN COLOURATION UNDER HOT TEMPERATURE ENVIRONMENTS. Acta Hortic. 929, 81-87
DOI: 10.17660/ActaHortic.2012.929.10
Malus × domestica Borkh., anthocyanins, gene expression, transcriptional regulation, MYB

Acta Horticulturae