Study of Genetic Diversity of Iranian Thymus Accessions, Using ISJ Semi-random Markers

Thymus is one of the famous medicine herbs of Lamiaceae genus. Due to the high potential of hybridization and introgression among thymus species, they have high genetic variability and study of genetic variability is difficult in this genus. According to the existing problems in the field of breeding of this medicine herb, use of molecular markers could be a valuable tool for evaluation and exploitation of germplasm. In this study, for assessment of genetic diversity among 70 Iranian Thymus, 30 semi-random ISJ (Intron-exon Splicing Junction) primers were used. Total primers produced 694 bands that 683 bands were polymorphic. Average band number per primer and per genotype was 23.13 and 9.91, respectively. Cluster analysis using DARwin5 software and UPGMA method based on Dice's similarity matrix divided accessions into 6 clusters. The highest similarity was estimated between T. kotschyanus and T. transcaucasius and lowest similarity was estimated between T. lancifolius and T. fedtschenkoi. The highest and lowest of polymorphic information content (PIC) revealed by IT 15-36 and IT 18-2 primers, respectively. The highest and lowest marker index (MI) included ET 15-33 and ET 18-6 primers, respectively. Results showed that clustering based on cluster analysis partly adapted with geographical origin dispersion. Totally, application of semi-random primers could be useful in assessment of genetic diversity of Thymus accessions.