Survey, collection, and conservation of wild Camellia oleifera Abel. and related species in Southwest and East China

Camellia oleifera Abel. is characterized by high oil content in its seeds and is widely distributed in the Yangtze River Basin and southern region of China. To understand the distribution and protection status of germplasm resources of C. oleifera and related species in China, and to strengthen the protection, exploration, and utilization of germplasm resources, we conducted field investigations at 55 survey sites in six provinces (30 districts/counties/cities) in southwest and eastern regions of China from 2016 to 2021. Results showed that germplasm resources were highly diverse and widely distributed, with common C. oleifera being the most abundant and widely dispersed. Among the 55 survey sites, 11% were in well-protected mountainous areas or nature reserves far from cities and towns. Other resources were scattered in mixed tree irrigation forests or old C. oleifera forest patches in remote mountainous areas, in generally protected or unprotected states. Many habitats have suffered serious damage, including frequent deforestation, road construction, and wasteland reclamation, and some resources were on the verge of extinction. A total of 778 dried leaf samples of wild C. oleifera were collected and 2444 germplasm resources were preserved by transplanting and grafting seedlings. These resources were stored in the C. oleifera Base of Fengming Agricultural Park in Ya'an (Sichuan, China) and the C. oleifera Expert Compound in Tianquan County (Sichuan, China). Based on the distribution and abundance of C. oleifera and related species, we discuss the possible risk factors and conservation issues as well as strategies and development directions for the conservation of the germplasm resources of these species.