Predominance of a single clone of the most widely distributed bamboo species Phyllostachys edulis in East Asia

摘要

Phyllostachys edulis, one of the most dominant bamboo species with the leptomorph rhizome system, has been asexually expanding its range into adjacent natural forest sites by shooting new culms. The resulting ecological problems include simplification of stand structure and decline in the species diversity of local flora. In this study, the genetic diversity of P. edulis for the entire distribution range from Japan to China was analyzed using 16 microsatellite markers. Among these, 12 loci were fixed by a single allele, whereas only two alleles were detected for each of the remaining 4 loci; all adult samples shared the same genotype at all loci including the four heterozygous loci. These observations indicate that all current samples from Japan and China comprise an identical clone. The clone is distributed over more than 2,800 km with an estimated biomass of approximately 6.6 x 10(11) kg, which is exceptionally large. Among seedlings from flowering events in 2005 and 2006, 20 different genets were generated by recombination through selfing of a single flowering genet. Predominance of a single clone in the wild and a diverse composition of genets among seedlings suggest that the intermittent flowering of P. edulis in the wild has produced a variety of clones through recombination. However, the resulting seedlings cannot compete with other tree species or adult P. edulis, and almost all adult P. edulis growing in Japan and China likely propagated through vegetative reproduction of a single clone by human transplantation, and subsequently expanded into adjacent forest sites by shooting young sprouts. The relatively small size of the flowering area and rapid culm reproduction has led to the stability of P. edulis communities. However, the low genetic diversity is an important consideration for the long-term management of this prevailing bamboo species.