Parentage Confirmation of Korean Bred Pear Cultivars by Simple Sequence Repeat SSR Genotyping and S-Genotypes Analysis

Abstract

Identification and authentication of parentage are important for effective pear breeding. Within Korean pear cultivars discrepancies are often reported between parents and offspring in skin color of fruits and also in S-genotypes suggesting that reported parentage was often inappropriate. In Korea, the parentage of the most of pear cultivars was never confirmed at the molecular level. Simple sequence repeat (SSR) genotyping and S-genotype analysis are considered effective in identifying parents. In this study, parentage of nine Korean bred cultivars was confirmed using SSR genotyping and S-genotype analysis. A total of 53 SSR markers were used. Six different haplotype-specific endonucleases were used for restriction cleavage of S-genotypes. Most of the Korean bred cultivars had six comparatively shorter S-RNase, S(1), S(3), S(4), S(5), S(6), or S(7) of 450 bp in length whereas the Japanese control cultivars had four other comparatively longer S-RNase. Out of nine pear cultivars only ``Chuwhangbae`` and ``Whangkeumbae`` had identical SSR genotypes and S-genotype with previously reported parents. For another cultivar, ``Sujeonbae``, the parents were the mutants of reported parent, ``Niitaka``. For four other cultivars, SSR and S-genotypes of offspring matched with only one reported parent ``Niitaka`` but those of another parent did not match. For the two other pear cultivars ``Soowhangbae`` and ``Sooyoung`` none of reported parents were confirmed by SSR genotyping and S-genotype analysis. Historically, the parent ``Niitaka`` was predominant in the Korean pear breeding programs because of its high yield potential and quality. The methods have been used in this study could be used to identify pear cultivars with diverse S-genotypes to eliminate any existing obscure parent-offspring relations.