June 2019, Vol. 4, No. 6, pp 152-160.
Molecular Characterization of Plectranthus esculenthus and Plectranthus rotundifolius using Simple Sequence Repeats
D. Yakubu¹, I. Bawa¹, U. M. Sesugh²
¹Department of Biochemistry, Federal University of Agriculture, Makurdi, Benue State, Nigeria.
²Department of Plant Breeding, Federal University of Agriculture, Makurdi, Benue State, Nigeria.
*Corresponding author’s e-mail: firstname.lastname@example.org
The Plectranthus genus comprises several species generally referred to as boldo, which are highly used in traditional medicine due to their anti-dyspeptic, analgesic and digestion-stimulating properties. This work was aimed at the molecular characterization of two species of Plectranthus genus (P. rotundifolius and P. esculenthus) and the intraspecific diversity of P. esculenthus (Bebot, Riyom and Longat), by means of the SSR technique and morphological markers. This study may be the nobel of SSR technique to characterize P. esculenthus and P. rotundifolius in Nigeria. Morphological analysis featured eleven characters; Plant height, length of branches, intermodal distance, length of tubers and tuber girth and leaf area were measured using a meter rule graduated in centimeters. In the cases of number of sprouted stems, number of leaves, number of branches as well as number of tubers, physical counting were noted. For tuber weight, a weighing balance was used. Principal components analysis was carried out on the data obtained, where the individual components responsible for the variation of the studied taxa were analyzed. Morphological characters derived from leaf, stem, root, and tubers were analysed numerically using cluster method. A cluster analysis was carried out on the DNA product. Morphological variability was observed at the cluster distance with P. rotundiifolius and P. esculenthus (Longat) having the shortest distance between clusters at (0.1) and P. esculenthus (Riyom) at (0.6) while P. esculenthus (Bebot) was the farthest away with a with morphological variability distance of 1.5 (15%). Principal components analysis captured the morphological traits at the third principal component (53.1, 85.3 and 100%) showing that the morphological traits measured may not be the true representative of the morphology of the plants as more traits are needed to distinguish them. Genetic variability was observed between the P. esculenthus (longat) and P. rotuntifolius species (50%), followed by P. esculenthus “Riyom” (15%) and P. esculenthus “Bebot” (10%). The genetic cluster analysis showed that the two plants are not the same as P. esculenthus (Riyom) was found to be more closely related to P. roduntifolius which is in contrast with the morphological cluster which placed P. esculenthus (Riyom) as the more closely related species to P. roduntifolius. The results of this study suggest that these plants should be regarded as different based on SSR markers contrary to current treatment which was based on only morphological traits.
Keywords: Genetic similarities; Morphological characterization; Molecular characterization; Simple sequence repeats; Plectranthus sp..