Genetic diversity analyses of Thymus daenensis and Thymus eriocalyx ecotypes using ISSR molecular marker

Recognizing genetic variation and classifying genetic resources are very important in the management and conservation of plant genetic resources. Thymus species (Lamiaceae), a number of which are found in Iran's flora, comprise herbaceous annual and perennial plants with significance in ethnomedicine. Here, the genetic diversities of twenty T. daenensis and T. eriocalyx ecotypes collected from different regions at the West Azerbaijan province (Iran) were investigated using ISSR molecular markers. Seven out of fifteen ISSR markers, with clear bands, were used. The cluster analysis using NTSYS-PC2 software and genetic structure by STRUCTURE Var 2.3.4 software were performed, and Nei distance was used for UPGMA method. A total number of five hundred and fifty-six polymorphic bands were obtained with an average of 79.42 bands per primer. The average percentage of polymorphic bands was calculated as 95.79% per primer. Eighty polymorphic loci with an average of 11.42 bands per primer were obtained, and P3 and P7 primers showed the highest (0.92) and the lowest (0.64) PIC values, respectively. Also, P2 and P5 primers showed the highest (15.89) and the lowest (5.2) MI values, respectively. Similarities varied from 0.2 (in ecotype TdS vs. ecotype TdPo and TdU1) to 0.67 (in ecotype TdPi vs. ecotype TdMo). The highest distinction between the groups was obtained at the cut point with four groups at a similarity level of 34%. According to the molecular variance analyses, most of the variations were seen within the groups. Finally, P2 and P3 primers are being recommended as efficient markers for genetic diversity analyses in Thymus species.