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Abstract Introducing and characterizing variation through mutagenesis plus functional genomics can accelerate resistance breeding as well as our understanding of crop plant immunity. To reveal new germplasm resources for fungal disease resistance breeding in elite durum wheat, we challenged the diverse alleles in a sequenced and cataloged ethyl methanesulfonate mutagenized population of elite tetraploid wheatTriticum turgidumsubsp.durumcv ‘Kronos’ with stripe rust. We screened 2,000 mutant lines and identified sixteen enhanced disease resistance (EDR) lines with persistent resistance to stripe rust over four years of field testing. To find broad-spectrum resistance, we challenged these lines with other major biotrophic and necrotrophic pathogens, including those causing Septoria tritici blotch, tan spot, Fusarium head blight and leaf rust. Enhanced resistance to multiple fungi was found in 13 of 16 EDR lines. Five EDR lines showed spontaneous lesion formation in the absence of pathogens, providing new mutant resources to study plant stress response in the absence of the confounding effects of pathogen infection. We mapped exome capture sequencing data of the EDR lines to a recently released long-read Kronos genome to aid in the identification of causal mutations. We located an EDR resistance locus to an 175 Mb interval on chromosome 1B. Importantly, these phenotypically characterized EDR lines are newly described durum germplasm coupled with improved functional genomics resources that are readily available for both wheat fungal resistance breeding and basic plant immunity research. 

Abstract Fusarium head blight (FHB; caused byFusarium graminearum) is a destructive disease of wheat (Triticumspp.), barley (Hordeum vulgare), rye (Secale cerealeL.), and triticale (×TriticosecaleWittmack) not only reducing their yield but also contaminating the grain with mycotoxins such as deoxynivalenol (DON). Developing varieties with genetic resistance is integral to successfully manage FHB. Triticale acreage worldwide is steadily increasing. However, the genetic diversity of triticale for FHB resistance is not well characterized. In the present study, a sequential screening of a set of winter triticale accessions from a global collection was done for their type‐2 FHB resistance and DON accumulation. In the first‐year screening, 298 triticale accessions were tested for FHB in an artificially inoculated, misted‐field nursery with high inoculum density. Most of the triticale accessions were susceptible to FHB, and only 8% of the accessions showed resistance in the field nursery screening. Next, the 24 resistant accessions identified in the nursery screening were tested for 2 years in greenhouse and 17 accessions showed significantly lower FHB severity in Year 2 and/or Year 3. These 17 resistant accessions were further tested for their FHB severity and DON accumulation in Year 4 in greenhouse and for DON accumulation in Year 5 in the field FHB nursery. Eight accessions showed significantly lower FHB severity and nine accessions showed DON accumulation of less than 1 mg/kg in Year 4 greenhouse testing. Eleven accessions had significantly lower DON concentration than the susceptible check in the Year 5 field screening. The resistant accessions common across all years identified in the study can be used for enhancing FHB resistance and reducing DON accumulation in triticale breeding programs. 

Abstract Feeding the world's ever‐increasing population requires continuous development of high‐yielding and disease‐resistant cultivars of food crops such as wheat (Triticum aestivumL.). Speed breeding, which utilizes longer photoperiod times and higher temperatures, is a technique that accelerates plant development and is rapidly being adopted by wheat breeders across the globe to fast‐track cultivar development. Plant diseases are a major threat to crop production, and breeding for disease resistance is a major goal of crop breeders. Fusarium head blight (FHB), caused byFusarium graminearum, is a major disease of small grain cereals, affecting their yield and quality. The aim of present work was to assess if speed breeding conditions can be used to accelerate reliable assessment of FHB severity and mycotoxin deoxynivalenol (DON) accumulation in wheat varieties. We screened a set of six spring wheat genotypes with different levels of genetic resistance (two moderately susceptible, two highly susceptible, one moderately resistant, and one resistant) for their response to FHB at 14 days after inoculation (dai) and 21 dai and DON accumulation under normal versus speed breeding conditions. FHB severity and DON accumulation were found to be highly correlated at all time points under normal and speed breeding conditions. Robust differentiation between resistant and susceptible genotypes could be achieved at 14 dai rather than the normal period of 21 dai, saving at least a week in phenotyping. Combined with the accelerated growth, flowering, and maturity under these conditions, efficient FHB screening and DON evaluation under speed breeding conditions will fast‐track development of resistant wheat varieties.