Genetic diversity and population structure of native and introduced date palm (Phoenix dactylifera) germplasm in the United Arab Emirates.

摘要

Date palm (Phoenix dactylifera) has been cultivated since ancient times, but little is known about its genetic diversity and population structure. Examination of 80 date palm accessions grown in the United Arab Emirates, including a collection of varieties from around the world, using 21 microsatellite markers, indicated extensive genetic diversity, with many accessions heterozygous for most markers. The average number of alleles per locus (19), expected heterozygosity (0.7), observed heterozygosity (0.25) and fixation indices (Fst=0.6, Rst=0.72) demonstrated significant population structure. Analysis with a model-based Baysian method, STRUCTURE 2.4.1, indicated that the 80 accessions could be broadly divided into nine groups. Independent samples of genotypes with the same name, collected from different experimental stations, usually clustered together. The study was enriched for germplasm from the United Arab Emirates (UAE), and one STRUCTURE-derived grouping consisted mainly of UAE accessions. In a few other clusters, several genotypes from the UAE, Iraq and Oman grouped together. Two clusters included accessions from both North Africa and the Middle East. Many accessions in the STRUCTURE-derived populations appeared to be genetic admixtures. The results indicated a broad dissemination of related germplasms across date-palm growing regions of the world, with very few alleles that still correlate with particular regional germplasms.