Fusarium head blight (FHB) incited by Fusarium graminearum Schwabe is a devastating disease of barley and other cereal crops worldwide. Fusarium head blight is associated with trichothecene mycotoxins such as deoxynivalenol (DON), which contaminates grains, making them unfit for malting or animal feed industries. While genetically resistant cultivars offer the best economic and environmentally responsible means to mitigate disease, parent lines with adequate resistance are limited in barley. Resistance breeding based upon quantitative genetic gains has been slow to date, due to intensive labor requirements of disease nurseries. The production of a high-throughput genome-wide molecular marker assembly for barley permits use in development of genomic prediction models for traits of economic importance to this crop. A diverse panel consisting of 400 two-row spring barley lines was assembled to focus on Canadian barley breeding programs. The panel was evaluated for FHB and DON content in three environments and over 2 years. Moreover, it was genotyped using an Illumina Infinium High-Throughput Screening (HTS) iSelect custom beadchip array of single nucleotide polymorphic molecular markers (50 K SNP), where over 23 K molecular markers were polymorphic. Genomic prediction has been demonstrated to successfully reduce FHB and DON content in cereals using various statistical models. Herein, we have studied an alternative method based on machine learning and compare it with a statistical approach. The bi-allelic SNPs represented pairs of alleles and were encoded in two ways: as categorical (–1, 0, 1) or using Hardy-Weinberg probability frequencies. This was followed by selecting essential genomic markers for phenotype prediction. Subsequently, a Transformer-based deep learning algorithm was applied to predict FHB and DON. Apart from the Transformer method, a Residual Fully Connected Neural Network (RFCNN) was also applied. Pearson correlation coefficients were calculated to compare true vs. predicted outputs. Models which included all markers generally showed marginal improvement in prediction. Hardy-Weinberg encoding generally improved correlation for FHB (6.9%) and DON (9.6%) for the Transformer network. This study suggests the potential of the Transformer based method as an alternative to the popular BLUP model for genomic prediction of complex traits such as FHB or DON, having performed equally or better than existing machine learning and statistical methods.

Fusarium head blight (FHB) is one of the most important diseases of barley in Manitoba province (western Canada), and other major barley producing regions of the world. Little is known about the Fusarium species and mycotoxin spectra associated with FHB of barley in Manitoba. Hence, barley grain samples were collected from 149 commercial fields from 2017 to 2019, along with information on respective cropping history, and analyzed with respect to Fusarium species spectra, abundance, chemotype composition, and mycotoxin profiles. Fusarium poae was the predominant Fusarium species associated with FHB of barley in Manitoba, followed by F. graminearum, and F. sporotrichioides; F. equiseti and F. avenaceum were also detected but at low levels. F. poae strains with the nivalenol (NIV) chemotype and F. graminearum strains with 3-acetyl deoxynivalenol (3-ADON) and 15-acetyl deoxynivalenol (15-ADON) chemotypes were commonly detected in the barley grain samples. Nivalenol (597.7, 219.1, and 412.4 µg kg⁻¹) and deoxynivalenol (DON) (264.7, 56.7, and 65.3 µg kg⁻¹) were the two most prevalent mycotoxins contaminating Manitoba barley in 2017, 2018 and 2019, respectively. A substantially higher DON content was detected in grain samples from barley fields with cereals as a preceding crop compared to canola and flax. Furthermore, F. poae proved less sensitive to four triazole fungicides (metconazole, prothioconazole+tebuconazole, tebuconazole, and prothioconazole) than F. graminearum. Findings from this research will assist barley producers with improved understanding of FHB threat levels and optimizing practices for the best management of FHB in barley.

Fusarium head blight (FHB) is a devastating disease in barley, causing significant losses for the malting and brewing industries. We hypothesized that the variation observed in Fusarium ‐related issues during malting may be partially attributable to differences among Fusarium graminearum strains. Field trials in 2019–2021 used barley cultivars with different FHB resistance: Newdale (intermediate) and AAC Goldman (moderately resistant). Barley plants were grown under disease‐conducive conditions, and plots were inoculated with conidial suspensions of each of seven different F. graminearum monoclonal isolates plus a noninoculated control. Disease severity (as a percentage of symptomatic spikelets) significantly differed among years (2020 > 2019 > 2021). F. graminearum density in barley varied significantly across years (2019 > 2021 > 2020). Pathogen strain identity and cultivar (Newdale > AAC Goldman) had significant effects on F. graminearum density in barley grain. The harvested barley was micromalted. The deoxynivalenol (DON) content in barley and malt significantly differed among years and cultivars, with the highest levels in 2019 and in Newdale. Pathogen strain identity significantly influenced DON content in barley and malt. F. graminearum density in malt showed significant variation among years (2021 > 2019 > 2020) and was influenced by the pathogen strain identity, while cultivar did not significantly affect F. graminearum density in malt. Gushing varied significantly across years but was not affected by cultivar or pathogen strain identity and was independent of F. graminearum density. Our finding that F. graminearum strain identity altered impact in barley grain and malt may explain the variability of FHB impacts.

Barley (Hordeum vulgare L.) is the fourth largest cereal crop in the world. One of the most devastating diseases in barley worldwide is Fusarium head blight (FHB) caused by Fusarium graminearum Schwabe. Several mycotoxins are produced by FHB infection, and deoxynivalenol (DON) is one of them responsible for the deterioration of grain quality. The current limited number of reliable molecular markers makes the development of FHB-resistant cultivars rather difficult and laborious. Moreover, there is a limited number of designed specific biomarkers that could distinguish the FHB resistance and mycotoxin accumulation in barley cultivars. This study investigated the phenolic compounds of ten different Canadian barley cultivars, grown in artificially FHB-infected and non-infected field trials. The enzyme-linked immunosorbent assay (ELISA) was used to assess the presence of DON in the harvested infected grains of each tested variety. High-performance liquid chromatography (HPLC) analysis was performed using both infected and non-infected samples. We identified differences among cultivars tested in non-infected samples through quantitative analysis of free and bound phenolic compounds. The resistant cultivars showed higher amounts of major bound phenolic compounds compared to the susceptible check CDC Bold. Additionally, the FHB-infected cultivars produced significantly higher amounts of sinapic acid (SIN) () and catechin (CAT) in the soluble free form of phenolics in barley compared to the non-infected subjects. This study suggests that phenolic compounds in barley could allow barley breeders to precisely identify and develop FHB-resistant barley germplasm and cultivars.

Spot blotch, caused by Bipolaris sorokiniana , is a growing concern for barley ( Hordeum vulgare ) production in most humid, temperate growing regions of the world. Under epidemic conditions, this disease can reduce yields significantly. Reduction of kernel plumpness is associated with lower malt extract and consequently grain quality. Enhanced resistance to this disease is a major goal of western Canadian two‐row barley breeding programmes; however, two‐row barley is considered to be more susceptible than six‐row barley. Plant–pathogen interactions observed for Canadian germplasm are polygenic, where quantitative breeding methods could be beneficial for the development of resistant germplasm. A germplasm panel consisting of 200 two‐row, spring barley genotypes with differential reaction to spot blotch was evaluated at Brandon, Manitoba (MB), and Melfort, Saskatchewan (SK), over eight site years. Genome‐wide association study was conducted using a 50k single‐nucleotide polymorphism (SNP) Illumina iSelect genotyping array. The most‐resistant germplasm was found to carry Midwest Six‐rowed Durable Resistant Haplotype (MSDRH) alleles at the loci located on chromosomes 1H (Rcs‐qtl‐1H‐11_10764), 3H (Rcs‐qtl‐3H‐11_10565) and 7H (Rcs‐qtl‐7H‐11_20162, Rcs5 locus), where the 3H locus was found to be the most under‐represented in Canadian germplasm. Additional marker‐trait associations within nurseries were identified on chromosomes 1H, 2H and 4H. Several of the SNP markers identified were found to be polymorphic within the Canadian two‐row germplasm panel and thus could be useful for enhancing spot blotch resistance in two‐row barley for development of resistant cultivars.

Barley grain harvested for malting poses an interesting case study for the impacts of plant‐associated microbiomes because the conditions created during malting favour continued vigorous microbial activity after grain harvest. Suppression of pathogens is among the key functions performed by microbiomes, and it would be beneficial if we could harness this function. Over a 3‐year field trial, we micro‐malted barley that had been experimentally infested with each of seven different strains of the fungal pathogen Fusarium graminearum , and profiled bacterial microbiomes at key stages in the malting process (grain, post‐steeping, post‐germination and final dried malt). The greatest impacts on bacterial microbiomes were observed to be from the year and stage of malting, with comparatively fewer impacts of barley cultivar or pathogen strain. Relatively limited impacts of the presence and strain identity of fungal pathogen on the bacterial microbiome of malting barley probably reflects the colonization by other fungi, as our inoculation took place under field conditions with supplemental irrigation. Both community level shifts and significant responses by individual taxa were evident. Microbiome characteristics or the relative abundances of specific bacterial taxa helped to explain pathogen biomass, mycotoxin production and beer gushing. Manipulative experiments will be required to test hypotheses suggested by these microbiome profiles.