Morphological and molecular characterization of leaf rust resistance in bread wheat (Triticum aestivum L.) line tester hybrids

The research was carried out according to the randomized block trial design in the Field Crops Experimental Area of the Faculty of Agriculture of Namık Kemal University in 2016-2017 cultivation period. Pehlivan, Sana, Tina, Tekirdağ, Gallipoli, Nina, F-85, Saban, Kate A-1 bread wheat varieties and brown rust resistance genes Lr 9, Lr 14, Lr 19, Lr 22, Lr 24, Lr 34 (father) isogenic lines crossed. In this study, F2 populations obtained as a result of cross-breeding wheat genotypes and isogenic lines containing Lr genes were planted in 5-row rows with 3 replications for each genotype. In the planting of F2 plants, Morocco genotype, which is sensitive to brown rust, was planted in every 10th order. Disease evaluations in the plants in the trial area were done in 2 periods (early and late) based on the modified Cobb scale (Peterson et al. 1948). It was determined that all hybrid combinations between bread wheat varieties and isogenic lines with Lr 9 and Lr 24 genes showed leaf rust resistance according to the disease readings in field conditions. On the other hand, hybrid progenies between bread wheat varieties and isogenic lines carrying Lr 14, Lr 19, Lr 22 and Lr 34 showed sensitive to leaf rust. According to the results of SSR analysis performed in the hybrid populations between three bread wheat genotypes and the isogenic line carrying 6 different brown rust resistance genes, it was determined that all F2 progenies carried Lr 9, Lr 19 genes. The Lr 22 gene was found at different rates in F2 plants of the hybrid combinations. The Lr 24 brown rust gene was transferred to all of the hybrid offspring made with the Flamura cultivar, while this ratio was 33% in the Saban hybrids. The Lr 34 gene was found to be different in the hybrid populations compared to the hybridized wheat genotype. The data obtained indicate that Lr 9 and Lr 24 leaf rust resistance genes are important selection criteria for Thrace region. The lack of the Lr 22 gene in the hybrid combinations between the bread wheat varieties and the isogenic line with the Lr 22 gene showed that more detailed studies should be carried out for this gene. Althoug the transfer of Lr 14, Lr 19, and Lr 34 brown rust resistance genes in hybrid populations, high rates of disease in F2 plants of these combinations indicate that these genes are not important in terms of disease races in Thrace region.