Kamali M, Ahmadikhah A, Pahlavani M.H, Dehghan M.A and Sheikh F
Pedigree-based selection method combined with marker-assisted selection (MAS) provides a suitable resource for deriving elite lines with more favorable characters. Using field experiments and molecular markers we evaluated diversity of wheat advanced F5 and F6 lines derived from cross Tajan/PBW299//MILAN/SHA7 aimed to select elite line(s) with favorable characters [resistance to yellow rust (YR) and fusarium head blight (FHB)]. Selection for several important traits, including resistance to yellow rust, fusarium head blight and general Tajan plant type was conducted during 5 and 6 generations. Genetic diversity of F5 and F6 lines was studied using 32 and 47 polymorphic loci produced by long AP-PCR primers. Results showed that there was a great diversity within and between studied advanced lines. Average gene diversity across polymorphic loci for the two generations was 29% and 28.8%, respectively. Genome content of Tajan cultivar in F5 lines ranged between 35% to 76.5% (with average of 57.5%). Five percent of F5 lines harbored 77% of Tajan genome. However, 62.8% to 90.2% (in average 75.8%) of F6 genome was inherited from Tajan. Five percent of F6 lines harbored ~90% of Tajan genome. These results indicate that advancing progenies from F5 to F6 increased the contribution of genome content of Tajan cultivar due to selection pressure in favor of Tajan plant type. Phenotypic evaluations in combination with MAS helped us to identify and select a few F6 elite lines resistant to YR and FHB with Tajan plant type. Our results markedly show that selection made by breeder has diverse effects on genetic structure of plant material, particularly in favor of fixating genetic background of superior parent.
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