Genetic diversity and genetic characteristics of Cryptomeria japonica in the Togakushi Okusha shrine forest

Abstract

We investigated size distribution, genetic diversity and characteristics of old Cryptomeria japonica trees at Togakushi Okusha shrine using eight nuclear microsatellite markers. The bimodal shape of size distribution in planted trees suggests that this stand was planted in acertain limited period. Many trees are revealed to be planted by cutting in this forest by multiple genotype analysis. The genetic diversity such as allelic richness and expected heterozygosity in Togakushi Okusha shrine forest and natural populations were similar in level; however, the principal coordinate analysis based on Nei's genetic distances showed that Togakushi Okusha shrine forest was unique among the natural populations. Kinship relations were detected between old trees in Togakushi Okusha shrine forest, other shrine and temple forests and a local cultivar in Nagano Prefecture. Genetic differentiation between Togakushi Okusha shrine forest and other natural forests were probably caused by the founder effect, due to the limited number of trees for forestation of the shrine forest. To maintain current genetic diversity and characteristics, we could recommend using seedlings deri ved from old trees showing good growth and traits and also cutting method for supplemental planting. Conservation of rare clonal individuals is also important to maintain genetic characteristics of trees which were planted in several shrine and temple forests for religious reasons.