Genetic Diversity Of Sorghum (Sorghum Bicolor (L.) Moench) And Its Wild Relatives In Namibia Using Ssr And Rapd Analyses

ABSTRACT

Sorghum bicolor (L.) Moench is the fifth most important cereal crop in the world, and in Namibia, sorghum is the second most important. The genetic resources of sorghum remain unexplored in Namibia. This could lead to a loss of genetic diversity as wild relatives and foreign varieties could interbreed with landraces, resulting in an undesired alteration of its genetic make-up. This study was conducted to evaluate the genetic diversity among the Namibian Sorghum bicolor accessions stored at NBRI (National Botanical Research Institute), two relatives (Sorghum halepense) and four improved varieties (Macia, Pato, Larsvyt 46-85 and ZSV/30). The objectives were (i) to assess the genetic diversity of Sorghum bicolor germplasm stored at the National Botanical Research Institute (NBRI) and (ii) to understand the germplasm genetic relationships among land races, wild relatives and improved cultivars using simple sequence repeat (SSR) and random amplified polymorphic DNAs (RAPDs). UPGMA (Unweighted Paired Group Method Using Arithmetic Average) based results revealed a measure of similarity among genotypes (r) =38 for RAPD analyses and at r =18 for SSR respectively for 24 genotypes. The measure of the magnitude of similarity of (r) = 5 were obtained for 63 genotypes using SSR, an ordination method, nonmetric multidimensional scaling (2D maps), confirmed the UPGMA results with stress values ranging from 0.05 to 0.2. Simpson’s diversity index (D) calculated for SSR analysis for 63 genotypes was: 1-D = 0.98 while RAPD and SSR on 24 genotypes was 1-D = 0.96. Shannon Wiener index was H′= 3.844 for SSR analysis on 63 genotypes and H′= 3.152 for RAPD and SSR on 24 genotypes. Two new primers (CD230935 and CD231028) designed have amplified mostly all the genotypes analyzed in this study. It was also concluded that there is a genetic variation among Sorghum bicolor at the gene level in Namibia. The study also revealed that RAPD and SSR techniques can be used in the evaluation of genetic diversity in sorghum species.