Genetic Diversity and Population Structure of Iranian tulips revealed by EST-SSR and NBS-LRR Markers

The genus Tulipa L. (Liliaceae) comprises about 100 species and Iran is considered as one of the main origins of tulips. In this research, genetic diversity and population structure of 27 wild populations of tulips collected from Iran were studied by 15 highly polymorphic and reproducible expressed sequenced tag-simple sequence repeat (EST-SSR) markers and 8 nucleotide binding site (NBS)-enzyme combinations. According to EST-SSR genotyping, the average of gene diversity (GD) and polymorphism information content (PIC) were 0.66 and 0.62, respectively. However, the values of GD and PIC were equal for each NBS primer–enzyme combination which ranged between 0.85-0.95 with a mean value of 0.91. The mean value of resolving power (EST-SSR = 1.93; NBS-LRR = 17.39) indicated that the NBS markers had higher discriminatory power compared to the EST-SSR markers. UPGMA clustering confirmed the results of PCA which was further confirmed by Bayesian model-based STRUCTURE analysis. Population structure analysis detected 3 and 4 gene pools for 27 wild tulip germplasms with EST-SSR genotyping and NBS-LRR profiling, respectively. The AMOVA results indicated that molecular variation among populations (ΦPT = inter-population variation) was 82% and 93% of the total variation for EST-SSR and NBS-LRR markers, respectively. The results of this study will help the conservation and phylogenetic studies of tulips.