SELECTION FOR IMPROVED FRUIT TEXTURE AND STORABILITY IN APPLE

Several different genes have been reported to affect fruit texture in apple.
We have analysed 158 cultivars for their allelic composition in the expansin gene Md-Exp7. Most of these cultivars had already been analysed for their allelic composition in the ethylene production-affecting gene Md-ACS1 but 29 additional cultivars were analysed also for this gene.
Finally, we harvested fruit from 114 cultivars and measured firmness with a penetrometer directly at harvest and after 6 weeks (early-ripening) or 12 weeks (late-ripening cultivars) of cold storage.
For the Md-Exp7 locus, an SSR allele with 198 bp has previously been suggested as a marker for the ability to retain fruit firmness during storage.
However, we found that another marker with 202 bp was over-represented in (1) cultivars that also carry the favourable allele 2 in the Md-ACS1 locus, and in (2) more recently developed cultivars, both of which suggest that recent selection in several apple breeding programs around the world has favoured allele 202 more than allele 198. In addition, preliminary data from the firmness evaluations also suggest that allele 202 is more closely associated with higher initial firmness and better firmness retention during storage.
Firmness was retained during storage to a very high degree by two ‘Antonovka’ types in spite of their unfavourable alleles in the Md-ACS1 and Md-Exp7 loci.
These cultivars could thus be valuable in the search for additional fruit texture genes.

XXVIII International Horticultural Congress on Science and Horticulture for People (IHC2010): International Symposium on Postharvest Technology in the Global Market

H. Nybom, M. Ahmadi-Afzadi, L. Garkava-Gustavsson , J. Sehic, I. Tahir

DNA marker, fruit firmness, Malus × domestica, MdACS1, MdEXP7

https://doi.org/10.17660/ActaHortic.2012.934.112