Validation of molecular markers for marker-assisted pyramiding of white rust resistance loci in Indian Mustard ( Brassica juncea L.)

Abstract

Singh, B. K., Nandan, D., Supriya, A., Ram, B., Kumar, A., Singh, T., Meena, H. S., Kumar, V., Singh, V. V., Rai, P. K. and Singh, D. 2015. Validation of molecular markers for marker-assisted pyramiding of white rust resistance loci in Indian Mustard (Brassica juncea L.). Can. J. Plant Sci. 95: 939–945. Successful application of molecular markers in marker-assisted pyramiding relies on effective determination of the target phenotype. In this respect, evaluation of the efficiency of markers for marker-assisted selection through cross-validation in different genetic backgrounds and in different populations is a crucial step. In the present study, the previously identified Arabidopsis-derived intron polymorphic (IP) markers At5g41560 and At2g36360, which were highly linked with AcB1-A4.1 and AcB1-A5.1, respectively, were validated in a set of 25 genotypes of Indian Mustard and in three different F 2 populations. The relationships between the variation of PCR products of the two markers with the percent disease index (PDI) of the tested genotypes, and the co-segregation analysis of the markers with disease phenotype in F 2 populations clearly indicated that At5g41560 and At2g36360 are genotype-nonspecific markers and are closely linked to white rust resistance loci AcB1-A4.1 and AcB1-A5.1, respectively. It also became evident from the present study that AcB1-A4.1 and an another white rust resistance locus Ac(2)t are likely the same gene locus.