Genetic Diversity of Loquat Accessions in Japan as Assessed by SSR Markers

The genetic variation of loquat (Eriobotrya japonica (Thunb.) Lindl.) was characterized by SSR markers developed from apple and pear, using 94 loquat accessions in Japan. Fourteen of the 24 SSR markers derived from apple could successfully produce amplified bands in loquat, whereas 10 of the 24 SSR markers derived from pear could generate amplified bands. Nine SSR markers were chosen for evaluation of the genetic diversity among 94 loquat accessions, including 61 cultivars from Japan and other countries and 33 natively grown accessions collected around Japan. A phenogram constructed using the unweighted pair-group method with arithmetic averages based on similarities between genotypes revealed two major groups. One group consisted mainly of cultivars from Japan and other countries, whereas the other group included only natively grown accessions. Some synonyms or mutants were found showing identical SSR genotypes. These results show that SSR markers can be utilized as reliable tools for genetic identification in loquat. The origins of current loquat cultivars in Japan are also discussed.