Phylogeography of Prunus Armeniaca L. By Chloroplast DNA and Nuclear Ribosomal Sequences

To clarify the phytogeography of Prunus armeniaca L., two chloroplast DNA fragments (trnL-trnF and ycf1) and the nuclear ribosomal DNA internal transcribed spacer (ITS) were employed to assess the genetic variation across 12 P. armeniaca populations. The results of cpDNA and ITS sequence data analysis showed that the level of genetic diversity in P. armeniaca was high (cpDNA: HT=0.499; ITS: HT=0.876), and the level of genetic differentiation was low (cpDNA: FST=0.1628; ITS: FST=0.0297). An analysis of molecular variance (AMOVA) revealed that most of the genetic variation in P. armeniaca occurred among individuals within populations. The value of interpopulation differentiation (NST) was significantly higher than the number of substitution types (GST), indicating a genealogical structure in P. armeniaca. P. armeniaca shared the same genotypes with related species and may be associated with them through continuous and extensive gene flow. The haplotypes/genotypes of cultivated apricot populations in Xinjiang, North China, and foreign apricot populations were mixed with large numbers of haplotypes/genotypes of wild apricot populations from the Ili River Valley. The wild apricot populations in the Ili River Valley contained the ancestral haplotypes/genotypes with the highest genetic diversity and were located in an area considered a potential glacial refugiume for P. armeniaca. Since population expansion occurred 16.53 kyr ago, the area has provided a suitable climate for the population and protected the genetic diversity of P. armeniaca.