Practical marker-assisted selection using two SCAR markers for fruit astringency type in crosses of 'Taiten' × PCNA cultivars in persimmon breeding

Pollination-constant, non-astringent (PCNA) type persimmons (Diospyros kaki Thunb.) steadily lose fruit astringency and are more desirable than other types of persimmons. The PCNA/non-PCNA trait is qualitatively controlled by AST/ast alleles at a single locus. Persimmons are hexaploid, and PCNA of Japanese origin and non-PCNA genotypes are denoted as aaaaaa and A-----, respectively, if AST gene denotes A and ast gene denotes a. 'Taiten' is an F1, non-PCNA persimmon offspring with genotype AAaaaa derived from PCNA × non-PCNA, and molecular markers linked AST alleles in 'Taiten' shows polymorphism as A2 and A3, so that the genotype of 'Taiten' can show A2A3aaaa using the alleles of molecular marker. Offspring from a backcross of 'Taiten' × 'Kanshu' (PCNA) were evaluated. The astringency type was analyzed phenotypically, by fruit sensory and brown specks tests, and genotypically by SCAR markers with PCR primer pairs (E4/A2r for detecting the SCAR marker A2 and 7H9F/AST-R for both A2 and A3). The ratio of PCNA offspring was 43/251 (17.1%), and there was discrepancy between the phenotypic evaluation and SCAR marker estimation in only 3 offspring. The ratio was not significantly different from the theoretical ratio of nulliplex in autohexaploid. The PCNA offspring segregation ratio was 36/151 (23.8%) for 'Fuyu' (PCNA) × 'Taiten' and 6/29 (20.7%) for 'Tenjingosho' (PCNA) × 'Taiten' (nearly the same ratio reported for 'Taiten' × 'Kanshu'). Marker-assisted selection using SCAR markers is thus effective and practical in persimmon breeding.