Genetic variability in Iranian Thymus pecies based on inter simple sequence repeat (ISSR) markers

Thyme is one of the most widely used and valuable medicinal plants in the world. To study the genetic diversity, 22 populations of Iranian thyme from four species, T. deanensis ,T. Pubescence ,T. kotschyanus and T. lancifolius as well as a population of T. vulgaris evaluated  by 12 ISSR primers. Ten ISSR primers produced detectable bands with 57 alleles. The highest amount of the PIC (Polymorphism Information Content) was detected in P9 primer with 0.92 PIC. Primers with AC and AG motifs produced sharper bands. Cluster analysis based on molecular data grouped the populations in two separate classes. The range of genetic distance between populations varied from 0.03 to 0.4. Daran-Isfahan population and T. vulgaris revealed the highest (I=0.43, h= 0.29) and the lowest (I=0.16, h= 0.106) intra-population variation, respectively. The intra- and inter-population diversities contributed 23% and 77% to total Variation, respectively. T. deanensis and T. lancifolius indicated the highest polymorphism with 98.25% and 77.44%, respectively while the lowest polymorphism was detected in T. vulgaris (35.9 %). The intra- and inter-species diversities contributed 10% and 90% to total variation, respectively. Results showed a great genetic variation in Iranian thyme species which could be considered in hybridization and breeding programs.