Cultivar Differentiation Identified by SSR markers and the Application for Polyploid Loquat Plants

Abstract

Here we established a DNA marker-based method to identify cultivars of loquat (Eriobotrya japonica Lindl.) using simple sequence repeat (SSR) markers derived from pears and apples. A total of 24 loquat cultivars commercially grown in Japan were used for genetic identification, including 15 diploid-, 6 triploid-, and 3 tetraploid cultivars. Analysis using the 88 SSR markers derived from pears and apples, which belong to the same subfamily (family Rosaceae, subfamily Maloideae) as the loquat, indicated that 26 SSR markers were applicable to the identification of loquat cultivars. A total of 82 putative SSR alleles were obtained by the 26 SSR markers. SSR analysis enabled the identification of all loquat varieties tested, except for ‘Tomihusa’ and ‘4N-Tomihusa’. In addition, the parentages of several cultivars, including ‘Oohusa’ and ‘Mizuho’, were confirmed from the SSR genotype data obtained. Triploid and tetraploid varieties could be identified from the SSR genotypes because some SSR loci generated 2 or more alleles for polyploids. The relationship between ‘Kibou’ and its parents was confirmed since SSR alleles of the seedless triploid offspring ‘Kibou’ were clearly inherited from the female parent ‘4N-Tanaka 1’ and the male parent ‘Nagasakiwase’. The phenogram obtained by cluster analysis showed no distinctive separation of Japanese commercial cultivars from Chinese cultivars. This result was consistent with the hypothesis that Japanese commercial cultivars were derived from introduced Chinese loquat.