Samples and Location
In this study, needles from 796 (873) trees of Chinese pine were collected from 35 (38) populations of the main natural and artificial populations in Shanxi, Hebei, and Liaoning Provinces of China (Figure 1-2 , Supplementary Table S1 ). 30-35 individuals (the distance between each individual was greater than 30m) were randomly selected from each population, and the new needles of Chinese pine were collected for follow-up experiments.