Association between blue mold resistance and qPCR-based molecular markers in apple

M. Ahmadi-Afzadi, H. Nybom, C. Kirk, D. Chagné
Apple cultivars vary in their susceptibility to Penicillium expansum, the causal agent of blue mold, which is one of the most devastating storage diseases in this crop. The genetic background to susceptibility/resistance has not yet been fully clarified, but significant associations have been detected between 1) the size of lesions caused by blue mold after artificial inoculation of harvested fruit, and 2) various fruit texture-related traits (e.g., fruit firmness at harvest and rate of fruit softening during storage) as well as 3) fruit biochemical contents (e.g., polyphenols). In the present study, 82 apple cultivars were phenotyped for fruit firmness, fruit softening rate and size of blue mold lesions after wound inoculation of newly harvested fruit with P. expansum spores. These cultivars were screened using 15 qPCR-based molecular markers targeting loci linked to fruit texture and chemical composition on apple linkage groups (LG) 10 and 16. The results revealed significant phenotype-genotype associations between two loci on LG 16 (ss475881696 and ss475882555) and lesion decay (p=0.047 and 0.037, respectively). In addition, a non-significant relationship (p=0.08) between softening rate and two fruit acidity-related loci on LG 16, ss475876558 and Ma1-SNP1455, was indicated. These results will be useful in further investigations of key genes for blue mold resistance, and for developing markers that can be applied in apple breeding programs.
Ahmadi-Afzadi, M., Nybom, H., Kirk, C. and Chagné, D. (2020). Association between blue mold resistance and qPCR-based molecular markers in apple. Acta Hortic. 1282, 277-284
DOI: 10.17660/ActaHortic.2020.1282.41
https://doi.org/10.17660/ActaHortic.2020.1282.41
breeding, fruit quality, Malus × domestica, Penicillium expansum, QTL, storage rot, taqman assay
English

Acta Horticulturae