Title : Study of genetic diversity of thymus satureioides in based on morphological traits and molecular markers ISSR
Abstract:
Thymus satureioides Coss. is an endemic and medicinal plant of Morocco, widely distributed in the arid and semiarid habitats. Communally used in traditional medicine to treat various infections. it is the most used and exported rare borneol thyme. Unfortunately, the degradation of the natural habitats and the climate Change are most factors for its conservation and domestication. There is no information on the intraspecific variations of the morphological and molecular features of this species. 12 Inter-Simple Sequence Repeats (ISSR) primers combined with 11 agro-morphological traits were applied to evaluate the intra- and inter variation. 60 accessions of T. satureioides collected from 10 spontaneous sites covering most geographical area, cultivated in two experimental stations Khémisset and Rabat. Phenotypic variation coefficient (CV) of the studied traits varied from 2.99 to 47.37% among biomass and number of inflorescence/stems. ANOVA showed very highly significant differences between accessions for all the studied traits (p <0.0001). PCA plot showed that 90.39% were the most six variable morphological characters. Among 80%, Cluster analysis grouped the accessions into two major clusters based on their morphological resemblance. AMOVA revealed that the Molecular variation within and between accessions was demonstrated to 82% and 18% respectively. The UPGMA dendrogram revealed two major groups, with a similarity of 80%. The number of bands is ranged from 12 for primer UBC825 to 28 for primer UBC4, those amplified 119 band and generating 739 amplicons. The UPGMA dendrogram, established through Nei’s genetic distances, exhibited two groups. PCoA plot revealed two major groups of populations and consistent with genetic relationships derived from Cluster analysis. Tamssount region recorded high values of genetic diversity (He= 0,182), percentage polymorphic loci (PPL=63.03%) and Shannon information index (I=0.283). These results highlighted a variability that will be useful for the breeding programme aiming at improving the productivity, conservation, and domestication of Thymus satureioides.
