Genetic diversity
The total length of aligned sequences for the three chloroplast fragments (matK , trnD-E , trnS-G ) was 2161 bp with 25 variable sites, including 21 single nucleotide variant sites, 2 6-bp insertions and 5 deletions in 323 individuals, and 661 bp for ITS with 10 variable sites in 174 individuals from 18 Cerasus serrulatapopulations. Results of diversity analyses were shown in Table 1. At species level, the haplotype diversity (H d) was 0.828 and the ribotype diversity (R d) was 0.673; the nucleotide diversity (P i) of cpDNA and ITS were 1.490 and 2.521, respectively. All of the data suggested a high genetic diversity of Cerasus serrulata . At population level,H d varied from 0.000 to 0.700 whileR d varied from 0.000 to 0.733;P i×10-3 of cpDNA varied from 0.000 to 1.090 while that of ITS varied from 0.000 to 2.820. Population CPL showed the highest haplotype diversity both in cpDNA and ITS regions. Combing the geographic distribution (Figure 1) along with haplotype distribution (Figure 1, 4), networks (Figure 2, 5) and cladograms (Figure 3, 6), four regions of groups were divided (Table 1). At region level, H d varied from 0.266 to 0.747 and R d varied from 0.246 to 0.752, whileP i varied from 0.280 to 1.940 for cpDNA, and from 0.370 to 1.670 for ITS. Both kinds of sequences revealed a lowest diversity level in Northwest China (NW). But differently, region in Southeast China (SE) showed a highest H d while region in Southwest China (SW) showed a highest Rd, indicating a highest haplotype/ribotype diversity level in South China.