Dendrocalamus giganteus Munro is a high-value woody bamboo widely grown in Southeast Asia and China's Yunnan Province. We investigated its genetic diversity in Yunnan as a prelude to considering effective breeding programs and the protection of germplasm resources. Inter-simple sequence repeat (ISSR) markers were used to assess the genetic structure and differentiation of seven populations. Seven ISSR primers generated 140 bands, of which 124 were polymorphic (88.57%). Genetic diversity within populations was relatively low, averaging 11.33% polymorphic bands (PPB), while diversity was considerably higher among populations, with PPB = 88.57%. Greater genetic differentiation was detected among populations (G ST = 0.8474). We grouped these seven populations into two clusters within an UPGMA dendrogram-one comprised the Xinping and Shiping populations from central Yunnan, the other included the remaining five populations. Mantel tests indicated no significant correlation between genetic and geographic distances among populations. Breeding system characteristics, genetic drift, and limited gene flow (N m = 0.0901) might be important factors for explaining this differentiation. Based on the overall high genetic diversity and differentiation among D. giganteus populations in Yunnan, we suggest the implementation of in situ conservation measures for all populations and sufficient sampling for ex situ conservation collections.

ABSTRACT. Camellia reticulata is a well-known ornamental and oil plant that is endemic to southwest China. This species shows three cell ploidies, i.e., diploidy, tetraploidy and hexaploidy. We made the first investigation of genetic diversity and differentiation of natural populations of C. reticulata, and 114 individuals from 6 populations were sampled. Cytogeography results showed that ploidy is invariable within populations and evenly distributed. A relatively high level of genetic diversity was found in C. reticulata, both at the species level (PPB = 88.89%; H = 0.2809; I = 0.4278) and at the population level (mean PPB = 42.13%; mean H = 0.14; mean I = 0.21). We found a relatively low degree of differentiation among ploidies (G ST = 0.2384; AMOVA = 10.26%) and a relatively high degree of differentiation among populations (G CS = 0.3807; AMOVA = 48.75%). The high genetic diversity can be explained by its biological char acter, wide distribution and ploidies, and the special genetic structure can be ascribed to polyploid origin from hybridization with different Camellia spp. This information will be useful for the introduction, conservation and further studies of C. reticulata and related species.