Genetic Variation among Koshu (Vitis vinifera L.) Accessions Generated by Retrotransposon Insertion into Genome

Koshu ( Vitis vinifera L.) is indigenous to Japan, where it is the most popular cultivar for white winemaking. Koshu grapevines have not been systematically classified according to yield, fruit quality, morphologic phenotype, and genetic variation. We report here the genetic variation among Koshu accessions classified by the region where they were cultivated. Eight retroelements were selected for inter-retrotransposon amplified polymorphism (IRAP) analysis and 16 retrotransposon-specific primers were designed. Polymerase chain reaction (PCR) using 136 primer sets amplified 731 PCR bands. Thirty-five polymorphic bands among Koshu accessions were identified by PCR using 24 primer sets. Individual grapevines from the same accession exhibited monomorphic band patterns for the primer sets. Cluster analysis based on polymorphic band patterns identified by IRAP analysis demonstrated that the Koshu accessions tested might be classified into three genetic groups. Results indicate that genetic variation among accessions might be generated by retrotransposon insertion into the Koshu genome.