SSR marker analysis for genetic diversity in the Zimbabwean Virginia tobacco (Nicotiana tabacum L.) germplasm

Abstract

Abstract Tobacco is one of the most economically important non-food crop in Zimbabwe and other tobacco producing countries globally. Currently, little is known about the genetic diversity of tobacco germplasm in Zimbabwe. Understanding the genetic diversity of tobacco germplasm offers significant help in the selection of suitable material for breeding superior cultivars. In this study, 10 SSR markers were employed to assess the genetic diversity and population structure of 93 tobacco breeding lines and cultivars. A total of 50 alleles on 10 SSR loci were detected and the allele number per loci ranged from 3 to 14. The average gene diversity index and average polymorphism information content (PIC) ranged from 0.53 and 0.48, respectively, showing low levels of genetic diversity among tobacco cultivars. The AMOVA result revealed a low level of differentiation among accessions from different origins. Based on SSR markers, the tobacco germplasm collections consistently showed very low levels of genetic differentiation using the Bayesian statistical analysis, cluster analysis and principal coordinate analysis consistently revealed the lack of differentiation among the germplasm collections. The genetic characterization of tobacco germplasm in seed bank repositories could be very useful for monitoring and preventing further genetic erosion andpreventing excessive inbreeding in new variety development.