ASSESSING GENETIC DIVERSITY AND POPULATION STRUCTURE OF THYME (THYMUS SCHIMPERI RONNIGER) IN EASTERN, CENTRAL AND NORTHERN HIGHLANDS OF ETHIOPIA

Abstract

ABSTRACT Thymus schimperiRonniger (Ethiopian thyme) is wild-growing endemic perennial herb which is rich in medicinally important metabolites. However, little is known about its genetic diversity and population genetic structure. Nine T. schimperi populations were collected from Bale, North Shewa and East Gojam zones of Ethiopia and analyzed using five ISSR markers. Seventy-seven amplicons showed an overall 100% polymorphism, corresponding to an average of 15.4 bands per primer. At the individual population level, the percentage of polymorphic loci (PPL) within population ranged from 63.64 % for Dargegne to 87.01 % for Rira population, with an average of 74%. Nei's genetic diversity (H) was 0.25 on average at the population level and 0.36 at the species level, while Shannon indices (I) were 0.39 and 0.54, respectively. Percentage of polymorphic bands (PPB) varied from 15.79% to 100% in different primers with an average of 75.2%. The Gst value for the overall loci was 0.31 indicating moderate differentiation among populations and lower gene flow (Nm = 1.133). AMOVA showed that total genetic variance, partitioned as 4%, 27% and 69% (P < 0.00) between populations from different regions, among populations within regions and within individual populations, respectively. Mantel’s test results with significance detected using ISSRs among all of the tested populations was; r = 0.304 (P < 0.001,999 permutations). UPGMA cluster analysis indicated grouping of the populations regardless of their geographical locations. This is the first report to demonstrate the use of molecular markers for diversity analysis in Ethiopian thyme and the result obtained suggests an urgent need for conservation of the existing natural population and implement alternative measures to meet the market demand.