Morphological and genetic diversity assessment of cultivated Thymus satureioides (endemic species) of Morocco

Abstract

Thymus satureioides is an endemic and medicinal plant of Morocco, widely distributed in the arid and semiarid habitats. Communally used in traditional medicine. In the current study, twelve Inter-Simple Sequence Repeats (ISSR) primers combined with 11 agro-morphological traits were applied to evaluate 60 accessions of T. satureioides collected from 10 spontaneous sites covering most geographical area. These accessions were cultivated in two experimental stations Khémisset and Rabat. Variation coefficient of Phenotypic studied traits (CV) varied from 2.99 (inflorescence/stems) to 47.37 % (secondary branches/stem number). ANOVA showed very highly significant differences between accessions for of of all the studied traits (p < 0.0001). The experimental station of Khémisset recorded the highest values compared to Rabat. PCA plot showed that 90.39 % were the most six variable morphological characters. At 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 number of bands is ranged from 12 for primer UBC825 to 28 for primer ISSR-4, those amplified 119 band and generating 739 amplicons. The UPGMA dendrogram, established through dissimilarity index, exhibited three groups. PCoA plot revealed three 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 program aiming at improving the productivity, conservation and domestication of Thymus satureioides.