Validation Assay of Md-ACS1, Md-ACO1, and Md-PG1 Molecular Markers Associated with Storability in Apples

Abstract

The purpose of this study was to examine the potential utility of marker-assisted selection (MAS) based on storability-associated molecular markers in apple breeding and to provide genotype information for the markers Md-ACS1, Md-ACO1, and Md-PG1 in apple genetic resources as basic data for the use of breeding materials. We analyzed 750 apple genetic resources to assess the allelic composition of Md-ACS1 and Md-ACO1, which play roles in the ethylene biosynthesis pathway, and Md-PG1, which is involved in cell wall degradation. For 108 of the genetic resources used for genotyping, we measured fruit firmness using a texture analyzer (10 mm plunger) at harvest and after 20 days of room temperature (20~25℃) storage. Md-ACS1 and Md-PG1 were found to be associated with changes in fruit firmness (the difference between firmness at harvest and after storage), with ACS1-2/2, PG1-1/1, and PG1-2/2 showing the lowest changes in fruit firmness. In addition, we found that changes in fruit firmness were smallest in late-harvest species, even for the same genotype. In contrast, Md-ACO1 appeared to be unrelated to the storability of fruit. Of the 750 apple genetic resources screened, the genotypes ACS1-2/2, and PG1-1/1 or PG1-2/2 were detected in 3.6% of accessions, including ‘Fuji’, bud mutation cultivars of ‘Fuji’, ‘Chubu’, and ‘Iwakami’. The Md-ACS1 and Md-PG1 markers could have potential utility in assessments of storability and applied in MAS to improve the efficiency of apple breeding.