Biological characteristics and conservation genetics of the narrowly distributed rare plant Cinnamomum chago (Lauraceae)

Cinnamomum chago (family Lauraceae) is an essential source of timber and oil. This plant is narrowly distributed in the western part of the Yunnan Province. In this study, the distribution, habitat, and biological characteristics of C. chago were examined through field investigation. The genetic diversity and the variation of the remnant populations were also studied using the inter-simple sequence repeat technique. Results showed that C. chago is mainly distributed in the upstream tributary mountains of Lancang River in Yunlong County of Yunnan Province. The species distribution exhibited a fragmented pattern with five isolated populations and high-frequency anthropogenic interference. A combination of morphological features (opposite leaves, pinnate leaf veins, absence of glandular fossa, large drupe, small punch, and pollen surface with triangular spike grain, with cushion bumps at the base) indicated that C. chago is a key phylogenetic taxon between the two sections of Asian Cinnamomum plants (Sect. Camphora (Trew) Meissn. and Sect. Cinnamomum). Analysis of the genetic diversity of C. chago indicated that it has a moderately high level of genetic diversity at the population and species levels (populations level: Ne = 1.629, H = 0.348, I = 0.504, and PPB = 83.3%; species level: Ne = 1.864, H = 0.460, I = 0.652, and PPB = 100%). Analysis of molecular variance revealed that 17% of the genetic variation was divided between the populations, whereas 83% was observed within the populations. Based on these results, we suggest the inclusion of C. chago in the Wild Plants with Extremely Small Populations in China. Moreover, the species should be given special attention and protection. Some strategies were proposed for the conservation of the C. chago populations.