Tuesday, August 9, 2016
Georgia Ballroom (Sheraton Hotel Atlanta)
In order to investigate genetic diversity and relatedness among walnut samples from different countries, ten microsatellite (SSR) loci were analyzed on 189 Persian walnut (Juglans regia L.) genotypes growing in 14 countries from three continents. The 10 SSR primer pairs were polymorphic and amplified 115 alleles, ranging from 3–25 per locus, with a mean value of 11.5 alleles per locus. The highest number of alleles (25) was observed in WGA32 locus, while WGA276 locus had the highest number of effective allele (7.6). PIC value ranged from 0.37 (WGA27) to 0.86 (WGA276) with an average of 0.69. Shannon’s information index (I = 1.59) revealed that diversity among walnut sampled from different country was high. The mean values of observed and expected heterozygosity were 0.62 and 0.73 respectively. According to the Nei's genetic identity, samples from Greece and Germany showed the lowest identity (0.639), while samples from Algeria and Morocco had the highest similarity (0.968). Samples collected from Iran had the highest number of alleles (7.2) and number of private alleles (12), as well as the highest amount for Shannon index (1.6), indicating higher diversity in this population compare to other studied populations. The highest amount of observed heterozygosity (0.71) was recorded in Greece accessions. Cluster analysis divided genotypes in the line of geographical regions. STRUCTURE software confirmed the results of the UPGMA and divided accessions into two main groups and separated samples from Europe and North Africa from samples of Near East and Greece. This data provide comprehensive information about the genetic diversity as well as the model of walnut distribution between different nations.
Keywords: SSR loci, Juglans regia, accession, cluster analysis, private allele