Genetic diversity of Castanea crenata in northern Japan assessed by SSR markers

The genetic diversity of wild chestnut populations naturally distributed in northern Japan was examined in the present study. Leaf samples from total of 245 individual chestnut trees were collected from 7 regions and genetic diversity was analyzed using 5 SSR (Simple Sequence Repeat) markers. Seventy-nine putative alleles were detected in all the populations with an average value of 15.8. The values of observed heterozygosity (H-O) per locus in all the populations ranged from 0.638 to 0.835. Average value of the observed heterozygosity in each population was 0.677-0.793, showing extensive genetic diversity in wild chestnut populations. Six populations were divided into 3 clades (Otaru, Tsugaru-Aomori-Minamikayabe-Shimokita and Tsukuba) based on the phenogram obtained. A very small genetic differentiation was found in the clade of Tsugaru-Aomori -Minaimkayabe-Shimokita, whereas there were rather large genetic differences from the other clades. When wild chestnut samples were compared with cultivated ones, no remarkable differences were observed in the heterozygosity value and the size range of alleles, suggesting that cultivated chestnuts were most likely selected from wild populations.