Assessment of genomic diversity among and within Iranian confectionery sunflower (Helianthus annuus L.) populations by using simple sequence repeat markers

Abstract

Genetic variation in 15 confectionery sunflower populations from different geographical regions of Iran was evaluated using microsatellites. Forty-three alleles were scored at 20 SSR loci. The average number of alleles per locus (na) and the effective allele number (ne) were 2.15 and 1.72, respectively. Observed heterozygosity (0.55) was higher than the expected (0.38) indicating lack of Hardy–Weinberg equilibrium. The genetic similarity matrix for individuals was constructed using Kosman and Leonard similarity coefficient, and Nei's Genetic Identity as well as Kosman's genetic distance was calculated among populations. Dendrograms were constructed by the unweighted pair-group method using arithmetic average (UPGMA) algorithm. The analysis of molecular variance revealed lower genetic variation among populations (14%), than within populations (86%). The average number of migrants (Nm) between populations based on AMOVA (Fst = 0.062) was 4.79. Results displayed high variation among individual plants, possibly because of the high allogamy. Genetic similarity between populations in this study could be considered as consequences of genetic equilibrium that has occurred over the long period of cultivation of confectionery sunflower in this region as well as seed exchange among provinces. The traditional assumption that selecting genotypes of different geographical origin will maximize the diversity available to a breeding project does not hold in confectionery sunflower.