Study of the genetic structure and gene flow in Persian walnut (Juglans regia L.) using SSR markers.

摘要

In this study, the genetic structure and the gene flow were analyzed using 17 SSR marker loci in 66 genotypes of the 6 populations of Juglans regia L. The number of alleles per locus ranged from 4 to 11, with a total 147 alleles and 8.65 alleles (na) and 5.16 effective alleles (ne) on average per loci. The expected heterozygosity varied between 0.65 and 0.87 and the polymorphism information content (PIC) ranged from 0.56 to 0.82. There were differences among populations regarding the number of effective alleles and the Shannon's information index (I). In all populations heterozygosity was slightly low, but diversity between and within the populations was high (I=1.5). The high degree of variability between and within populations could be attributed to the heterogenizing effect of wind pollination. The average Fst value was 0.08. The level of gene flow based on Fst was high (Nm=3.01), which means that the high level of genetic diversity maintained within each population was less susceptible to genetic drift. The high amount of gene flow would reduce the disjunction among these populations. In addition, the geographical proximity of the populations was not correlated with their level of genetic relatedness. These results provide evidence of the high potential of walnut populations of Kerman province for breeding programs.