Inheritance of resistance to common bunt, tilletia caries and T. foetida, and identification of RAPD markers linked to bunt resistance in wheat
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Common bunt causes yield loss and reduces grain quality in common and durum wheats in western Canada. In order to aid bunt resistance breeding, this study was conducted to investigate the race-specificity and the inheritance of resistance to common bunt and to identify RAPD markers linked to bunt resistance for use in marker-assisted selection. In the study on race specificity of resistance, significant differences in resistance to bunt among cultivars and in virulence among races were found. Race T1 was found to be the least virulent and T19 was the most virulent. Race-specific resistance was demonstrated in all experiments. Both common (Kite and Triple Dirk) and spelt (RL5407 and SK0263) wheats were used for studies on the inheritance of resistance to bunt. Generation mean analysis showed that additive effects were the main genetic effects and dominance effects were not significant in any cross. Epistatic effects may exist in the cross Laura/Kite. Gene estimates from the qualitative analysis indicated that Triple Dirk and RLS407 may carry a single gene for resistance to race T1, T13 and L7. Kite may carry two genes and SK0263 carries either one or two genes for resistance to race T1. Heritability was estimated to be moderate to high (54%-90%) for bunt resistance to races T1, T13 and L7. An allelic study demonstrated that RL5407 may not carry 'Bt2 Bt3, Bt6, Bt8' or 'Bt10' genes for bunt resistance. RL5407 and SK0263 likely carry the same gene for resistance to race T1, and this gene is different from the gene carried by SK0505. RL5407 possibly carries a gene conditioning resistance to both races T13 and L7 in addition to the one for resistance to race T1. The genes carried by Triple Dirk for resistance to races T1, T13 and L7 are different from each other. No cytoplasmic effect was found for resistance to race T1 in the crosses Genesis/RL5407 and RL5407/Genesis. Two flanking RAPD markers linked to resistance to bunt race T1, UBCS48 590 (in repulsion) and UBC274988 (in coupling), were identified in Laura/RL5407. They had linkages of 9.1 ± 4.0 cM and 18.2 ± 5.6 cM, respectively.