Evaluation of yellow rust resistance in backcross populations of wheat

Aim: To screen wheat populations derived from cross DBW17 × WH1105 for loci imparting yellow rust resistance and selection of plants using polymorphic SSRs. Methodology: The study for yellow rust resistance was carried out on two populations, i.e., BC1F2 and BC2F2. Stress was provided by planting infector rows between the blocks and by artificial inoculation using a mixture of races 46S102, 47S103 and 78S84 of stripe rust pathogen. DNA isolated from young leaves was checked for the presence of yellow rust resistance genes using gene specific primers. Results: Fifteen primers were found to be polymorphic among parents DBW17 and WH1105. Fifteen polymorphic SSR markers were dispersed over the wheat genome (AABBDD), with allele range 2-5. These polymorphic SSR markers were used to produce molecular diversity among progeny lines. Cluster analysis of parents and both the populations, showed that two parents were diverse genetically and in both backcrosses progeny lines resembled their respective recurrent parent. Single marker analysis using data revealed that primers on nine chromosomes were associated with grain yield per plant, other yield attributes and yellow rust resistance in both populations. Interpretation: This study showed that a linked marker like Xgwm582 could be a promising tool for breeding wheat with enhanced tolerance to yellow rust resistance. However, growth rates and biomass production provide reliable criteria for assessing the degree of yellow rust resistance and the ability of a plant to withstand it.