A core collection of wild Populus alba L. germplasm in northwest China

The core germplasm collection of forest trees is of great value in genetic conservation and breeding. In the inland northwest of China, Populus alba is an excellent fast-growing, timber, and windbreak tree species. Due to its advantages of easy propagation, drought resistance, and cold resistance, it has become an important breeding parent for Populus . This study explored the expansion history and migration routes of P. alba in northwest China. As the population migrated from west to east and from downstream to upstream along the two main rivers in northern Xinjiang of China, the constantly shrinking population size was revealed. For long-term preservation and utilization, a core collection of germplasm was constructed. The core collection covers over 95 % of the genetic diversity of all germplasms. Six phenotypic traits, including rooting rate, rooting coefficient, SPAD, Fv / Fm , plant height and ground diameter of all germplasms were evaluated. The analysis of six phenotypic traits demonstrated that the core collection effectively represents the phenotypic variation in seedlings across all germplasms. This study provides essential materials and data for exploring the evolutionary history, local adaptation, and germplasm conservation of P. alba . • The expansion history of Populus alba in northwest China. • Genetic and phenotypic diversity of P. alba in northwest China. • A P. alba core collection covering over 95 % genetic diversity of all germplasm in northwest China.