Identification of molecular markers for screening tobacco germplasm resistant to white mould

Abstract

White mould is a fungal disease of tobacco and other crops and is caused by Golovinomyces cichoracearum. White mould resistance is introduced into commercial varieties by backcrossing followed by phenotypic selection which lengthens the breeding cycle. In order to reduce the breeding cycle molecular markers have to be identified to help in the screening and selection of germplasm resistant to white mould. The purpose of this study was therefore to identify the DNA markers that can assist breeders when they are selecting for resistant plants. Two resistant parental lines XZ, STNCB and two susceptible parental lines XSR, K51 were used in this study. Backcrosses of XZ and XSR were grown in the greenhouse and DNA extracted for molecular analysis. A total of eight (8) simple sequence repeat markers and ten (10) inter-simple sequence repeat markers were used. These markers were screened on the parental lines and the backcross generations for the differences between resistant and susceptible material. Locus PT30021 was the only marker that showed linkage to white mould resistance gene, and thus managed to distinguish between the resistant and the susceptible materials. Locus PT30021 has the potential of being used in the identification of white mould resistant germplasm in marker assisted backcrossing.