Assessment of genetic diversity and search for Plum pox virus resistance alleles of apricot (Prunus armeniaca L.) genotypes spread in Azerbaijan using SSR markers

Apricot is one of the most important stone-fruit plants widely cultivated in Azerbaijan. SSR markers were used to evaluate the genetic diversity of 61 apricot genotypes representing the entire gene pool in Azerbaijan. A total of 138 alleles were produced based on 17 SSR markers with an average of 8.1 alleles per primer. The polymorphism information content (PIC) and expected (He) heterozygosity for individual loci were in the range of 0.42-0.8 (mean 0.68) and 0.52-0.82 (mean 0.72), respectively, indicating the abundant genetic variation in Azerbaijani apricot cultivars. The polymorphisms generated by SSRs were enough to differentiate 95% of genotypes, while 4 apricot cultivars exhibited complete similarity between them. NJ tree grouped the 61 genotypes into 7 clusters with 1000 bootstrap values, where the grouping of genotypes was not closely related to the geographic origin or collection site. STRUCTURE analysis identified 4 subpopulations in the collection and, in general, was in agreement with cluster analysis. (SEO)/Harlayne-type resistance alleles of three SSR (PGS1.21-240 bp, PGS1.23-161 bp, PGS1.24-119 bp) and one SSLP loci (ZP002-127 bp) were detected in 3, 15, 15, and 9 accessions, respectively. STRUCTURE analysis could separate genotypes with resistance alleles grouping them in the first two subpopulations. Of the 61 apricot genotypes, 28 had at least one resistance allele. The results demonstrate that Azerbaijani apricots are an important source for breeding PPV-resistant apricots.