Simple Sequence Repeat Polymorphism in Iranian Citrus Germplasm Including Unknown Variants

摘要

Citrus accessions including several undefined local or native genotypes originated from the regions of Caspian Sea (Iran) as well as some known varieties were analyzed by simple sequence repeat (SSR) markers. The aim of the present research work was to characterize 33 accessions of citrus, with unknown pedigrees, to assess their genetic diversity and to elucidate their possible relationships with 12 commercially important varieties. Sixteen SSR primer pairs with high levels of polymorphism, which have been previously developed for citrus, were used in this study. A total of 104 alleles were obtained for all the microsatellites studied, ranging from 2 to 13 alleles per locus, with a mean value of 6.5 alleles per locus. Polymorphic information contentvaried from 0.252 to 0.879 with mean of 0.610. The percentage of heterozygosity per marker detected in our samples ranged from 2.30 to 100 % with an average of 46.22 %. The genetic distance matrix was used to construct neighbor joining cluster which allowed the arrangement of all the genotypes according to their genetic relationships. The genetic relationships among known citrus varieties with uncharacterized citrus natural types are discussed. By analyzing dendrogram, it is confirmed that mandarin (Citrus reticulata), pummelo (C. grandis), and citron (C. medico) were clustered into three particular groups as major species of Citrus. The obtained data confirmed the usefulness of SSR markers for estimation of citrus genetic diversity.