Enhancing Fusarium crown rot resistance by pyramiding large-effect QTL in barley

Abstract

Fusarium crown rot (FCR) is a serious disease in wheat and barley in semiarid regions worldwide. The feasibility of enhancing FCR resistance by gene pyramiding was investigated by generating and assessing two populations segregating for three large-effect QTL located on the long arms of chromosomes 1H, 3H and 4H, respectively. Significant effects were detected for each of the three QTL in both of the populations assessed. Lines with any combination of two resistant alleles from the three QTL gave, on average, significantly better resistance than those with a single resistant allele only, and lines with resistant alleles from all three of the QTL gave the least FCR symptom. However, wide variations in FCR severity were detected for lines belonging to each of the groups with different numbers of resistant alleles. Significant effects of plant height on FCR were detected in both populations, and a significant association between heading date and FCR severity was detected in one of the two populations assessed. Results from the current study also showed that the effects of a given allele of resistance decreased with the increase in the number of resistant alleles an individual group possessed. Overall, results from this study demonstrate that gene pyramiding can be an effective approach in improving FCR resistance and those lines with resistant alleles from all of the three QTL could be valuable for breeding programs.