PhD Candidate, University of Manitoba
Disease resistance breeding for fusarium head blight disease of wheat
Wheat is a major staple food crop and Canada is one of the major wheat exporters in the world. Increased productivity of both spring and winter wheat will be required in order to meet the demands of a growing world population. Fusarium head blight (FHB) caused by Fusarium graminearum is one of the major diseases of wheat around the world, including North America and it has been continuously reported as major threat to wheat yield in Canada. Fusarium head blight infection reduces grain yield, affects end-use quality, and leads to the accumulation of mycotoxins such as deoxynivalenol (DON), which affects food and feed safety. The wheat-F. graminearum pathosystem is complex due to multiple types of host resistance, variability in pathogen virulence and pathogenicity, and the influence of the environment on disease incidence and severity. As a result, breeding for FHB resistance is a cumbersome effort. The objective of this research was to identify Quantitative Trait Loci (QTL) associated with FHB resistance. A doubled haploid soft white winter wheat population consisting of 107 lines from the cross D8006W/Superior was used. Evaluation for FHB reaction was performed using spray inoculation of a macroconidia mixture of four F. graminearum isolates representing two chemotypes in replicated field disease nurseries in three locations in Canada in 2016 and 2017. Disease incidence and severity were recorded 21 days post inoculation and FHB index was calculated. Percentage Fusarium damaged kernels and DON content were measured from collected grain samples. Both parental lines showed moderate reaction across all environments for FHB traits. However, the population showed transgressive segregation for FHB reaction with a wide continuous distribution. Genotyping of the population was performed using the 90K Illumina Infinium iSelect single nucleotide polymorphism array and 5194 high quality SNP were selected for analysis. Linkage mapping and QTL analysis is under processing. This experiment will be repeated in field nurseries in 2018. Significant FHB resistance QTL identified from this project will be used in winter wheat breeding programs using marker assisted selection.
Abstract: Recent increases of Fusarium head blight (FHB) disease caused by infections with F. poae (FP) and F. langsethiae (FL) have been observed in oats. These pathogens are producers of nivalenol (NIV) and T-2/HT-2 toxin (T-2/HT-2), respectively, which are now considered major issues for cereal food and feed safety. To date, the impact of FP and FL on oat grains has not yet been identified, and little is known about oat resistance elements against these pathogens. In the present study, the impact of FL and FP on oat grains was assessed under different environmental conditions in field experiments with artificial inoculations. The severity of FP and FL infection on grains were compared across three field sites, and the resistance against NIV and T-2/HT2 accumulation was assessed for seven oat genotypes. Grain weight, β-glucan content, and protein content were compared between infected and non-infected grains. Analyses of grain infection showed that FL was able to cause infection on the grain only in the field site with the highest relative humidity, whereas FP infected grains in all field sites. The FP infection of grains resulted in NIV contamination (between 30-500 μg/kg). The concentration of NIV in grains was not conditioned by environmental conditions. FL provoked an average contamination of grains with T-2/HT-2 (between 15-132 μg/kg). None of the genotypes was able to fully avoid toxin accumulation. The general resistance of oat grains against toxin accumulation was weak, and resistance against NIV accumulation was strongly impacted by the interaction between the genotype and the environment. Only the genotype with hull-less grains showed partial resistance to both NIV and T-2/HT-2 contamination. FP and FL infections could change the β-glucan content in grains, depending on the genotypes and environmental conditions. FP and FL did not have a significant impact on the thousand kernel weight (TKW) and protein content. Hence, resistance against toxin accumulation remains the only indicator of FHB resistance in oat. Our results highlight the need for new oat genotypes with enhanced resistance against both NIV and T-2/HT-2 to ensure food and feed safety.
Pub.: 25 Jan '18, Pinned: 25 Jan '18