Assessment of genetic variability in groundnut (Arachis hypogaea L.) genotypes grown under South African conditions using agronomic and SSR markers

Abstract

Groundnut (Arachis hypogeae) is a legume crop grown in arid and semi-arid regions of the world. The objective of the study was to assess the presence of genetic diversity among fifty three groundnut genotypes of diverse origin using eleven agronomic and twenty SSR markers. The analysis of variance showed that highly significant variations exist among the genotypes for all phenotypic traits measured. Five principal components showed 71% of the total phenotypic variation. The SSR loci showed high values of polymorphic information content ranging from 0.31 to 0.89, with a mean of 0.71. Heterozygosity values ranged between 0.03 and 1.00 with a mean of 0.57. The genotypes showed a wide range of allelic diversity from 3 to 16, with a mean of 8.1 alleles per locus. Analysis of molecular variance (AMOVA) indicated that larger variability (59%) was due to variation within individuals, whilst the remaining variation was accounted for variation among individuals within population. Cluster analysis grouped the genotypes into two distinct clusters, where it showed that the discrimination of the genotypes was not dependant on the origin of the genotypes. The high gene flow observed among the different geographic origin might contribute to the low differentiation among the population. The SSR and phenotypic markers were able to detect wide genetic diversity and discriminate groundnut genotypes. The two genetically distinct groups observed in this study, can be used as source of genes of novelty and parental lines for transgressive segregation and for further broadening of the genetic base of the crop