Abstract:

Population genetic structure was studied using fluorescent-AFLP markers on 45 apricot (Armeniaca Mill.) accessions collected from the Dzhungar-Zailij group, Xinjiang cultivated apricot sub-group and Liguang apricot sub-group in the Central Asian group, the European group, and the Northern China group. A. mume, A. sibirica, and A.mandshurica were used as outgroup of fluorescent-AFLP markers. The purpose of this study was to determine the genetic structure and genotypic diversity amongst the different eco-geographical populations. The results showed that the average number of polymorphic loci (A) was 130.86, the percentage of polymorphic loci (P) was 60.58% by 7 pairs of EcoRI/MseI (Mse I-a FAM fluorescent marked primer) primers in common apricot of four groups. Analysis for the average number of polymorphic loci (A) and the percentage of polymorphic loci (P) in four common apricot groups indicated that the Dzhungar-Zailij group (P = 43.59%)＞ the Xinjiang cultivated apricot sub-group in the Central Asian group (P = 41.27%)＞ the Northern China group (P = 39.42%)＞ the European group (P = 39.42%) ＞ the Liguang apricot sub-group in the Central Asian group (P = 37.57%). Nei's gene diversity (H = 0.143) and Shannon information index (I = 0.226) at species level were higher than ones at group level with significant or highly significant differences. At group level, Nei's gene diversity and Shannon information index (H = 0.131; I = 0.202) in the Dzhungar-Zailij group were higher than that in the Xinjiang cultivated apricot sub-group in the Central Asian group (H = 0.127; I = 0.195), or in the European group (H = 0.124; I = 0.189), or in the Northern China group (H = 0.116; I = 0.180) with no significant differences, respectively, but were significant higher than that in the Liguang apricot sub-group in the Central Asian group (H = 0.113; I = 0.173). Genetic differentiation coefficient (G_ST = 0.147) for four apricot groups showed that apricot genetic variation was mainly within the groups and accounted for 85.3% of total variations. The gene flow N_m = 2.901, according to the genetic differentiation coefficient between groups (G_ST = 0.147), indicated that there were partly gene exchanges among four apricot groups. Occasional seedling introduced by human beings could be the main way of gene exchanges and geographical barriers could be the main factor of hindering gene exchanges. The analysis of genetic diversity and genetic structure from four geo-ecological groups suggested that common apricot originated in the Dzhungar-Zailij geo-ecological group, then diffused to central Asia and formed cultivated apricot center in central Asia by domestication. It was further disseminated by human introduction to the East forming the Northern China group, and to the West forming the European group.

Key words: Armeniaca Mill., Apricot, fluorescent-AFLP, Genetic diversity, Population genetic diversity