Construction of a comprehensive meteorological risk index for wheat Fusarium head blight prediction based on more than a half-century of monitoring data.

Fusarium head blight (FHB) represents a critical threat to wheat production globally, not only reducing yields but also contaminating crops with harmful mycotoxins. This study aimed to elucidate new spatiotemporal patterns of FHB incidence and to develop a comprehensive meteorological risk index to enhance scientific prevention and control of the disease. Through the analysis of annual and decadal variations from 1965 to 2023, the study assessed FHB trends across four agricultural regions (I, II, III, and IV) in Jiangsu Province, located in the middle and lower reaches of the Yangtze River-a hotspot for FHB in China. Key findings include: Since 1965, Regions I and III consistently exhibited higher FHB incidence rates compared to Regions II and IV. Post-2000, there was a notable increase in years with high incidence rates, with Region III overtaking Region I as the region with the highest incidence. Since 2010, occurrences of FHB reaching the most severe grade (Grade 5) have surpassed those in previous decades across all regions. The study also revealed a stronger correlation between meteorological factors (cumulative precipitation, number of days with rainfall ≥ 0.1 mm, total rainy days with ≥ 2 and ≥3 consecutive days of rain, total rainy days with both average daily air temperature ≥ 15 °C and daily rainfall ≥ 0.1 mm, days with average daily relative humidity ≥ 85%, cumulative sunshine hours, and cumulative cloudy days) and the FHB incidence rates during the heading-flowering-grain filling period in Regions I, II, and III, compared to the heading-flowering period alone. This indicates that optimal temperature and high humidity during the grain filling stage significantly contribute to the final FHB incidence rates. Despite the less apparent correlation between temperature changes and disease rates, the significant warming trend observed since 2000 has likely fostered conditions conducive to the proliferation of FHB. The comprehensive meteorological risk index, constructed to incorporate key meteorological factors during the heading-flowering-filling period, showed a strong correlation with actual disease incidences. The index demonstrated fitting accuracy rates of 84.7% for Region I, 72.9% for Region II, 83.1% for Region III, and 90.9% for Region IV, underscoring its effectiveness in predicting FHB occurrences. This tool offers both convenience and practicality, providing valuable insights for strategically managing FHB risks based on local weather conditions.

ATP-binding cassette transporter TaABCG2 contributes to Fusarium head blight resistance by mediating salicylic acid transport in wheat.

ATP-binding cassette (ABC) transporters hydrolyse ATP to transport various substrates. Previous studies have shown that ABC transporters are responsible for transporting plant hormones and heavy metals, thus contributing to plant immunity. Herein, we identified a wheat G-type ABC transporter, TaABCG2-5B, that responds to salicylic acid (SA) treatment and is induced by Fusarium graminearum, the primary pathogen causing Fusarium head blight (FHB). The loss-of-function mutation of TaABCG2-5B (ΔTaabcg2-5B) reduced SA accumulation and increased susceptibility to F. graminearum. Conversely, overexpression of TaABCG2-5B (OE-TaABCG2-5B) exerted the opposite effect. Quantification of intracellular SA in ΔTaabcg2-5B and OE-TaABCG2-5B protoplasts revealed that TaABCG2-5B acts as an importer, facilitating the transport of SA into the cytoplasm. This role was further confirmed by Cd2+ absorption experiments in wheat roots, indicating that TaABCG2-5B also participates in Cd2+ transport. Thus, TaABCG2-5B acts as an importer and is crucial for transporting multiple substrates. Notably, the homologous gene TaABCG2-5A also facilitated Cd2+ uptake in wheat roots but did not significantly influence SA accumulation or FHB resistance. Therefore, TaABCG2 could be a valuable target for enhancing wheat tolerance to Cd2+ and improving FHB resistance.

Pathogenicity and Metabolomic Characterization of Fusarium graminearum and Fusarium poae Challenge in Barley under Controlled Conditions.

Barley is the third most important cereal crop in terms of production in Canada, and Fusarium head blight (FHB) is one of the main fungal diseases of barley. FHB is caused by a species complex of Fusaria, of which Fusarium graminearum Schwabe is the main causal species of FHB epidemics in Canada. Field surveys show that two or more Fusarium species often co-exist within the same field or grain sample, and F. poae is reported as another important species in barley. This study aimed to determine the pathogenicity of F. graminearum, F. poae, and a co-inoculation of both species causing FHB in barley. Two susceptible barley cultivars were spray-inoculated at 10 to 14 days after heading. Phenotypic disease severity was rated on a scale of 0-9 at 4, 7, 14, 21, and 28 days after inoculation. There was a significant difference in FHB severity between F. graminearum and F. poae, where infection with F. graminearum produced more severe disease ratings. F. poae generated lower disease ratings and was not statistically different from the control. When heads were co-inoculated with both Fusarium species, the resulting FHB severity was unchanged relative to heads inoculated with F. graminearum only. The ratio of F. graminearum to F. poae genomic DNA was also no different than when heads were inoculated with F. graminearum alone, as quantified with ddPCR using markers specific to each species. The metabolomic analysis of sample extracts showed that F. graminearum-associated metabolites dominated the mycotoxin profile of co-inoculated samples, which corroborated our other findings where F. graminearum appeared to outcompete F. poae in barley. No significant effect on visual FHB disease ratings or fungal DNA detection was observed between the cultivars tested. However, there were some metabolome differences between cultivars in response to the challenge by both F. graminearum and F. poae.

Leveraging trait and QTL covariates to improve genomic prediction of resistance to Fusarium head blight in Central European winter wheat.

Fusarium head blight (FHB) is a devastating disease of wheat, causing yield losses, reduced grain quality, and mycotoxin contamination. Breeding can mitigate the severity of FHB epidemics, especially with genomics-assisted methods. The mechanisms underlying resistance to FHB in wheat have been extensively studied, including phenological traits and genome-wide markers associated with FHB severity. Here, we aimed to improve genomic prediction for FHB resistance across breeding programs by incorporating FHB-correlated traits and FHB-associated loci as model covariates. We combined phenotypic data on FHB severity, anthesis date, and plant height with genome-wide marker data from five Central European winter wheat breeding programs for genome-wide association studies (GWAS) and genomic prediction. Within all populations, FHB was correlated with anthesis date and/or plant height, and a marker linked to the semi-dwarfing locus Rht-D1 was detected with GWAS for FHB. Including the Rht-D1 marker, anthesis date, and/or plant height as covariates in genomic prediction modeling improved prediction accuracy not only within populations but also in cross-population scenarios.

FgCWM1 modulates TaNDUFA9 to inhibit SA synthesis and reduce FHB resistance in wheat.

BACKGROUND: Fusarium head blight (FHB) significantly impacts wheat yield and quality. Understanding the intricate interaction mechanisms between Fusarium graminearum (the main pathogen of FHB) and wheat is crucial for developing effective strategies to manage and this disease. Our previous studies had shown that the absence of the cell wall mannoprotein FgCWM1, located at the outermost layer of the cell wall, led to a decrease in the pathogenicity of F. graminearum and induced the accumulation of salicylic acid (SA) in wheat. Hence, we propose that FgCWM1 may play a role in interacting between F. graminearum and wheat, as its physical location facilitates interaction effects. RESULTS: In this study, we have identified that the C-terminal region of NADH dehydrogenase [ubiquinone] 1 alpha subcomplex subunit 9 (NDUFA9) could interact with FgCWM1 through the yeast two-hybrid assay. The interaction was further confirmed through the combination of Co-IP and BiFC analyses. Consistently, the results of subcellular localization indicated that TaNDUFA9 was localized in the cytoplasm adjacent to the cell membrane and chloroplasts. The protein was also detected to be associated with mitochondria and positively regulated complex I activity. The loss-of-function mutant of TaNDUFA9 exhibited a delay in flowering, decreased seed setting rate, and reduced pollen fertility. However, it exhibited elevated levels of SA and increased resistance to FHB caused by F. graminearum infection. Meanwhile, inoculation with the FgCWM1 deletion mutant strain led to increased synthesis of SA in wheat. CONCLUSIONS: These findings suggest that TaNDUFA9 inhibits SA synthesis and FHB resistance in wheat. FgCWM1 enhances this inhibition by interacting with the C-terminal region of TaNDUFA9, ultimately facilitating F. graminearum infection in wheat. This study provides new insights into the interaction mechanism between F. graminearum and wheat. TaNDUFA9 could serve as a target gene for enhancing wheat resistance to FHB.

QTL analysis of native Fusarium head blight and deoxynivalenol resistance in 'D8006W'/'Superior', soft white winter wheat population.

BACKGROUND: Fusarium head blight (FHB), caused by Fusarium graminearum, is a major disease of wheat in North America. FHB infection causes fusarium damaged kernels (FDKs), accumulation of deoxynivalenol (DON) in the grain, and a reduction in quality and grain yield. Inheritance of FHB resistance is complex and involves multiple genes. The objective of this research was to identify QTL associated with native FHB and DON resistance in a 'D8006W'/'Superior', soft white winter wheat population. RESULTS: Phenotyping was conducted in replicated FHB field disease nurseries across multiple environments and included assessments of morphological and FHB related traits. Parental lines had moderate FHB resistance, however, the population showed transgressive segregation. A 1913.2 cM linkage map for the population was developed with SNP markers from the wheat 90 K Infinium iSelect SNP array. QTL analysis detected major FHB resistance QTL on chromosomes 2D, 4B, 5A, and 7A across multiple environments, with resistance from both parents. Trait specific unique QTL were detected on chromosomes 1A (visual traits), 5D (FDK), 6B (FDK and DON), and 7D (DON). The plant height and days to anthesis QTL on chromosome 2D coincided with Ppd-D1 and were linked with FHB traits. The plant height QTL on chromosome 4B was also linked with FHB traits; however, the Rht-B1 locus did not segregate in the population. CONCLUSIONS: This study identified several QTL, including on chromosome 2D linked with Ppd-D1, for FHB resistance in a native winter wheat germplasm.

The Emerging Fusarium graminearum NA3 Population Produces High Levels of Mycotoxins in Wheat and Barley.

Fusarium graminearum (Fg) is the primary causal agent of Fusarium head blight (FHB) in wheat, barley, and other small grains in North America and worldwide. FHB results in yield reduction and contaminates grain with mycotoxins that pose threats to human and livestock health. Three genetically distinct North American (NA) populations of Fg have been characterized, which are generally associated with differences in their predominant trichothecene chemotype: NA1/15-acetyl-deoxynivalenol (15-ADON), NA2/3-acetyl-deoxynivalenol (3-ADON), and NA3/3α-acetoxy, 7,15-dihydroxy-12,13-epoxytrichothec-9-ene (NX-2). Recent studies found that the NA3 population had significantly less spread on point-inoculated wheat spikes than the NA1 and NA2 populations, and NX toxins are important for Fg spread and initial infection in wheat. In this follow-up study, to compare the effect of the three populations on initial infection and mycotoxin production on different hosts, we dip-inoculated spikes of the moderately resistant wheat cultivar Alsen and the susceptible barley cultivar Voyager using five strains from each population to evaluate disease, trichothecene mycotoxin accumulation, and trichothecene production per unit of fungal biomass. In dip-inoculated wheat spikes, the NA3 population produced significantly more trichothecene per unit of fungal biomass and accumulated higher levels of trichothecene per plant biomass than the NA1 and NA2 populations, regardless of the disease levels caused by the three populations. In contrast to its critical role during wheat infection, NX toxins had no effect on barley infection. In dip-inoculated barley, the NA1 population was more infectious and caused more severe FHB symptoms than the NA2 and NA3 populations; however, the NA3 population produced significantly higher toxin per unit of fungal biomass in infected barley tissues than the NA1 population. This study provides critical information on the emerging NA3 population, which produces high levels of NX toxin and poses a potential food safety concern.

Identification and Differentiation of the Fusarium graminearum NX-2 Chemotype Using High-Resolution Melting (HRM).

Fusarium head blight causes significant yield losses in wheat and other cereals and contaminates grain products with trichothecene mycotoxins. F. graminearum isolates are classified into different chemotypes depending on the type of mycotoxin produced, including the type B trichothecenes 3-acetyl deoxynivalenol (3-ADON), 15-acetyl deoxynivalenol (15-ADON), nivalenol (NIV), and the recently identified type A trichothecene NX-2. Molecular tools to differentiate NX-2 producers from other chemotypes have remained relatively laborious and time consuming. In this study, we developed and validated a high-resolution melting (HRM) assay that can identify NX-2 producers quickly and cost-effectively. By analyzing TRI1 coding sequences from 183 geographically diverse isolates representing all four F. graminearum chemotypes, we selected a 75-base pair region containing four non-synonymous single nucleotide polymorphisms (SNPs) that are specific to the NX-2 genotypes. The amplicon generated two HRM profiles, one of which was specific for only NX-2. We confirmed that the assay is robust across qPCR platforms and unambiguously differentiates NX-2 from other chemotypes using a panel of 72 diverse isolates previously collected from North America. The HRM assay was also successful in identifying NX-2 producers directly from DNA extracted from infected wheat spikes with varying levels of disease severity and fungal DNA. The assay can detect as little as 0.01 ng of fungal DNA in a background of 50 ng of plant DNA. This new diagnostic assay can be used for high-throughput molecular detection of the NX-2 chemotype of F. graminearum from infected plant samples and culture collections, thus making it a valuable tool for surveys of contemporary and historical FHB pathogen populations.

Coat Proteins of the Novel Victoriviruses FaVV1 and FaVV2 Suppress Sexual Reproduction and Virulence in the Pathogen of Fusarium Head Blight.

Fusarium head blight (FHB), a disease inflicted by Fusarium graminearum and F. asiaticum, poses a growing threat to wheat in China, particularly in the face of climate change and evolving agricultural practices. This study unveiled the discovery of the victorivirus FgVV2 from the F. asiaticum strain F16176 and comprehensively characterized the function of the two victoriviruses FaVV1 and FaVV2 in virulence. Through comparative analysis with a virus-free strain, we established that these mycoviruses markedly repress the sexual reproduction and pathogenicity of their fungal hosts. Furthermore, we synthesized the coat protein (CP) genes CP1 from FaVV1 and CP2 from FaVV2, which were fused with the green fluorescent protein (GFP) gene and successfully expressed in Fusarium strains in wild-type isolates of F. asiaticum and F. graminearum. Similar to virus-infected strains, the transformed strains expressing CPs showed a significant decrease in perithecia formation and pathogenicity. Notably, CP2 exhibited a stronger inhibitory effect than CP1, yet the suppression of sexual reproduction in F. graminearum was less pronounced than that in F. asiaticum. Additionally, the pathogenicity of the F. asiaticum and F. graminearum strains expressing CP1 or CP2 was substantially diminished against wheat heads. The GFP-tagged CP1 and CP2 revealed distinct cellular localization patterns, suggesting various mechanisms of interaction with the host. The findings of this study provide a significant research foundation for the study of the interaction mechanisms between FaVV1 and FaVV2 with their hosts, as well as for the exploration and utilization of fungal viral resources.

Using Transcriptomics to Determine the Mechanism for the Resistance to Fusarium Head Blight of a Wheat-Th. elongatum Translocation Line.

Fusarium head blight (FHB), caused by the Fusarium graminearum species complex, is a destructive disease in wheat worldwide. The lack of FHB-resistant germplasm is a barrier in wheat breeding for resistance to FHB. Thinopyrum elongatum is an important relative that has been successfully used for the genetic improvement of wheat. In this study, a translocation line, YNM158, with the YM158 genetic background carrying a fragment of diploid Th. elongatum 7EL chromosome created using 60Co-γ radiation, showed high resistance to FHB under both field and greenhouse conditions. Transcriptome analysis confirmed that the horizontal transfer gene, encoding glutathione S-transferase (GST), is an important contributor to FHB resistance in the pathogen infection stage, whereas the 7EL chromosome fragment carries other genes regulated by F. graminearum during the colonization stage. Introgression of the 7EL fragment affected the expression of wheat genes that were enriched in resistance pathways, including the phosphatidylinositol signaling system, protein processing in the endoplasmic reticulum, plant-pathogen interaction, and the mitogen-activated protein kinase (MAPK) signaling pathway at different stages after F. graminearium infection. This study provides a novel germplasm for wheat resistance to FHB and new insights into the molecular mechanisms of wheat resistance to FHB.

Adaptation of Fusarium Head Blight Pathogens to Changes in Agricultural Practices and Human Migration.

Fusarium head blight (FHB) is one of the most destructive wheat diseases worldwide. To understand the impact of human migration and changes in agricultural practices on crop pathogens, here population genomic analysis with 245 representative strains from a collection of 4,427 field isolates of Fusarium asiaticum, the causal agent of FHB in Southern China is conducted. Three populations with distinct evolution trajectories are identifies over the last 10,000 years that can be correlated with historically documented changes in agricultural practices due to human migration caused by the Southern Expeditions during the Jin Dynasty. The gradual decrease of 3ADON-producing isolates from north to south along with the population structure and spore dispersal patterns shows the long-distance (>250 km) dispersal of F. asiaticum. These insights into population dynamics and evolutionary history of FHB pathogens are corroborated by a genome-wide analysis with strains originating from Japan, South America, and the USA, confirming the adaptation of FHB pathogens to cropping systems and human migration.

Molecular Investigations to Improve Fusarium Head Blight Resistance in Wheat: An Update Focusing on Multi-Omics Approaches.

Fusarium head blight (FHB) is mainly caused by Fusarium graminearum (Fg) and is a very widespread disease throughout the world, leading to severe damage to wheat with losses in both grain yield and quality. FHB also leads to mycotoxin contamination in the infected grains, being toxic to humans and animals. In spite of the continuous advancements to elucidate more and more aspects of FHB host resistance, to date, our knowledge about the molecular mechanisms underlying wheat defense response to this pathogen is not comprehensive, most likely due to the complex wheat-Fg interaction. Recently, due to climate changes, such as high temperature and heavy rainfall, FHB has become more frequent and severe worldwide, making it even more urgent to completely understand wheat defense mechanisms. In this review, after a brief description of the first wheat immune response to Fg, we discuss, for each FHB resistance type, from Type I to Type V resistances, the main molecular mechanisms involved, the major quantitative trait loci (QTLs) and candidate genes found. The focus is on multi-omics research helping discover crucial molecular pathways for each resistance type. Finally, according to the emerging examined studies and results, a wheat response model to Fg attack, showing the major interactions in the different FHB resistance types, is proposed. The aim is to establish a useful reference point for the researchers in the field interested to adopt an interdisciplinary omics approach.

Control of Fusarium Head Blight of Wheat with Bacillus velezensis E2 and Potential Mechanisms of Action.

Wheat plants are impacted by Fusarium head blight (FHB) infection, which poses a huge threat to wheat growth, development, storage and food safety. In this study, a fungal strain was isolated from diseased wheat plants and identified as Fusarium asiaticum F1, known to be a member of the Fusarium graminearum species complex, agents causally responsible for FHB. In order to control this disease, new alternatives need to be developed for the use of antagonistic bacteria. Bacillus velezensis E2 (B. velezensis E2), isolated from a previous investigation in our laboratory, showed a notable inhibitory effect on F. asiaticum F1 growth and deoxynivalenol (DON) synthesis in grains. The spore germination of F. asiaticum F1 was significantly reduced and the spores showed vesicular structures when treated with B. velezensis E2. Observations using scanning electron microscopy (SEM) showed that the hyphae of F. asiaticum F1 were shrunken and broken when treated with B. velezensis E2. The RNA-seq results of F1 hyphae treated with B. velezensis E2 showed that differentially expressed genes (DEGs), which were involved in multiple metabolic pathways such as toxin synthesis, autophagy process and glycan synthesis, especially the genes associated with DON synthesis, were significantly downregulated. In summary, those results showed that B. velezensis E2 could inhibit F. asiaticum F1 growth and reduce the gene expression of DON synthesis caused by F1. This study provides new insights and antagonistic mechanisms for the biological control of FHB during wheat growth, development and storage.

Biological and molecular characterization of pydiflumetofen and phenamacril dual-resistant Fusarium graminearum strains.

BACKGROUND: Fusarium head blight (FHB) caused by Fusarium graminearum species complex (FGSG) remains a major challenge to cereal crops and resistance to key fungicides by the pathogen threatens control efficacy. Pydiflumetofen, a succinate dehydrogenase inhibitor, and phenamacril, a cyanoacrylate fungicide targeting myosin I, have been applied to combat this disease. Nonetheless, emergence of pydiflumetofen resistance in a subset of field isolates alongside laboratory-induced facile generation of phenamacril-resistant isolates signals a critical danger of resistance proliferation. RESULTS: Our study investigates the development of dual resistance to these fungicides in F. graminearum. Utilizing pydiflumetofen-resistant (PyR) and -sensitive (PyS) isolates, we obtained dual-resistant (PyRPhR) and phenamacril-resistant (PySPhR) mutants on potato sucrose agar containing phenamacril. Mutation rates for phenamacril resistance were comparable between pydiflumetofen-resistant and -sensitive isolates, implying independent pathways for resistance development. The mutants compromised in fungal growth, competitive viability and deoxynivalenol production, suggesting fitness penalties for the dual-resistant mutants. However, no cross-resistance was found with tebuconazole or fludioxonil. In addition, we characterized four critical amino acid changes (S217L, C423R, K537T, E420G) in the Myo1 that were verified to confer phenamacril resistance in F. graminearum. CONCLUSION: This research indicates the possibility of resistance development for both pydiflumetofen and phenamacril in F. graminearum and emphasizes the need for fungicide resistance management for FHB. © 2024 Society of Chemical Industry.

Biocontrol of Fusarium head blight in rice using Bacillus velezensis JCK-7158.

Fusarium head blight (FHB) is a destructive disease caused by several species of Fusarium, such as Fusarium graminearum and F. asiaticum. FHB affects cereal crops, including wheat, barley, and rice, worldwide. Fusarium-infected kernels not only cause reduced yields but also cause quality loss by producing mycotoxins, such as trichothecenes and zearalenone, which are toxic to animals and humans. For decades, chemical fungicides have been used to control FHB because of their convenience and high control efficacy. However, the prolonged use of chemical fungicides has caused adverse effects, including the emergence of drug resistance to pathogens and environmental pollution. Biological control is considered one of the most promising alternatives to chemicals and can be used for integrated management of FHB due to the rare possibility of environment pollution and reduced health risks. In this study, Bacillus velezensis JCK-7158 isolated from rice was selected as an ecofriendly alternative to chemical fungicides for the management of FHB. JCK-7158 produced the extracellular enzymes protease, chitinase, gelatinase, and cellulase; the plant growth hormone indole-3-acetic acid; and the 2,3-butanediol precursor acetoin. Moreover, JCK-7158 exhibited broad antagonistic activity against various phytopathogenic fungi and produced iturin A, surfactin, and volatile substances as active antifungal compounds. It also enhanced the expression of PR1, a known induced resistance marker gene, in transgenic Arabidopsis plants expressing ß-glucuronidase (GUS) fused with the PR1 promoter. Under greenhouse conditions, treatments with the culture broth and suspension concentrate formulation of JCK-7158 at a 1,000-fold dilution inhibited the development of FHB by 50 and 66%, respectively. In a field experiment, treatment with the suspension concentrate formulation of JCK-7158 at a 1,000-fold dilution effectively controlled the development of FHB with a control value of 55% and reduced the production of the mycotoxin nivalenol by 40%. Interestingly, treatment with JCK-7158 enhanced the expression of plant defense-related genes in salicylic acid, jasmonic acid, ethylene, and reactive oxygen species (ROS) signaling pathways before and after FHB pathogen inoculation. Taken together, our findings support that JCK-7158 has the potential to serve as a new biocontrol agent for the management of FHB.

Molecular and Cytological Identification of Wheat-Thinopyrum intermedium Partial Amphiploid Line 92048 with Resistance to Stripe Rust and Fusarium Head Blight.

Thinopyrum intermedium (2n = 6x = 42, EeEeEbEbStSt or JJJsJsStSt) contains a large number of genes that are highly adaptable to the environment and immune to a variety of wheat diseases, such as powdery mildew, rust, and yellow dwarf, making it an important gene source for the genetic improvement of common wheat. Currently, an important issue plaguing wheat production and breeding is the spread of pests and illnesses. Breeding disease-resistant wheat varieties using disease-resistant genes is currently the most effective measure to solve this problem. Moreover, alien resistance genes often have a stronger disease-resistant effect than the resistance genes found in common wheat. In this study, the wheat-Th. intermedium partial amphiploid line 92048 was developed through hybridization between Th. intermedium and common wheat. The chromosome structure and composition of 92048 were analyzed using ND-FISH and molecular marker analysis. The results showed that the chromosome composition of 92048 (Octoploid Trititrigia) was 56 = 42W + 6J + 4Js + 4St. In addition, we found that 92048 was highly resistant to a mixture of stripe rust races (CYR32, CYR33, and CYR34) during the seedling stage and fusarium head blight (FHB) in the field during the adult plant stage, suggesting that the alien or wheat chromosomes in 92048 had disease-resistant gene(s) to stripe rust and FHB. There is a high probability that the gene(s) for resistance to stripe rust and FHB are from the alien chromosomes. Therefore, 92048 shows promise as a bridge material for transferring superior genes from Th. intermedium to common wheat and improving disease resistance in common wheat.

Insights into Wheat Genotype‒Sphaerodes mycoparasitica Interaction to Improve Crop Yield and Defence against Fusarium graminearum: An Integration of FHB Biocontrol in Canadian Wheat Breeding Programmes.

Fusarium head blight (FHB) is a major threat to wheat crop production and food security worldwide. The creation of resistant wheat cultivars is an essential component of an integrated strategy against Fusarium graminearum, the primary aetiological agent that causes FHB. The results of this study show that the deployment of proto-cooperative interactions between wheat genotypes and mycoparasitic biocontrol agents (BCAs) can improve crop yield and plant resistance in controlling the devastating effects of FHB on wheat agronomic traits. A Fusarium-specific mycoparasite, Sphaerodes mycoparasitica, was found to be compatible with common and durum wheat hosts, thus allowing the efficient control of F. graminearum infection in plants. Four genotypes of wheat, two common wheat, and two durum wheat cultivars with varying FHB resistance levels were used in this greenhouse study. The BCA treatments decreased FHB symptoms in all four cultivars and improved the agronomic traits such as spike number, spike weight, seed weight, plant biomass, and plant height which are vital to grain yield. Conversely, the F. graminearum 3ADON chemotype treatment decreased the agronomic trait values by up to 44% across cultivars. Spike number, spike weight, and seed weight were the most improved traits by the BCA. A more measurable improvement in agronomic traits was observed in durum wheat cultivars compared to common wheat.

Cumin Seed Oil Induces Oxidative Stress-Based Antifungal Activities on Fusarium graminearum.

In this study, the antifungal activity of cumin seed oil (CSO) was tested on Fusarium graminearum. (i) Minimum inhibitory concentrations (MICs) and related concentrations (IC75, IC50, and IC25) were detected; (ii) toxicity was evaluated by a water-soluble tetrazolium salt-1 (WST-1) assay; (iii) genomic/epigenomic alterations were evaluated by the coupled restriction enzyme digestion-random amplification (CRED-RA) method; (iv) oxidative stress was investigated by CAT expression, catalase activity, and DCF-DA staining; (v) deoxynivalenol biosynthesis was evaluated by tri6 expression; (vi) and potential effects of CSO on wheat were tested by a water loss rate (WLR) assay. MIC, IC75, IC50 and IC25 values were detected at 0.5, 0.375, 0.25, and 0.125 mg mL-1. In WST-1 assays, significant decreases (p < 0.001) were detected. Genomic template stability (GTS) related to methylation differences ranged from 94.60% to 96.30%. Percentage polymorphism for HapII/MspI values were as 9.1%/15.8%. CAT (oxidative stress-related catalase) and tri6 (zinc finger motif transcription factor) gene expressions were recorded between 5.29 ± 0.74 and 0.46 ± 0.10 (p < 0.05). Increased catalase activity was detected (p < 0.05) by spectrophotometric assays. DCF-DA-stained (oxidative stressed) cells were increased in response to increased concentrations, and there were no significant changes in WLR values. It was concluded that CSO showed strong antifungal activity on F. graminearum via different physiological levels.

A comparison between the role of enniatins and deoxynivalenol in Fusarium virulence on different tissues of common wheat.

BACKGROUND: Fusarium graminearum and Fusarium avenaceum are two of the most important causal agents of Fusarium head blight (FHB) of wheat. They can produce mycotoxins that accumulate in infected wheat heads, including deoxynivalenol (DON) and enniatins (ENNs), produced by F. graminearum and F. avenaceum, respectively. While the role of DON as a virulence factor in F. graminearum toward wheat is well known, ENNs in F. avenaceum has been poorly explored. Results obtained to-date indicate that ENNs may confer an advantage to F. avenaceum only on particular hosts. RESULTS: In this study, with the use of ENN-producing and ENN non-producing F. avenaceum strains, the role of ENNs on F. avenaceum virulence was investigated on the root, stem base and head of common wheat, and compared with the role of DON, using DON-producing and DON non-producing F. graminearum strains. The DON-producing F. graminearum strain showed a significantly higher ability to cause symptoms and colonise each of the tested tissues than the non-producing strain. On the other hand, the ability to produce ENNs increased initial symptoms of the disease and fungal biomass accumulation, measured by qPCR, only in wheat heads, and not in roots or stem bases. LC-MS/MS analysis was used to confirm the presence of ENNs and DON in the different strains, and results, both in vitro and in wheat heads, were consistent with the genetics of each strain. CONCLUSION: While the key role of DON on F. graminearum virulence towards three different wheat tissues was noticeable, ENNs seemed to have a role only in influencing F. avenaceum virulence on common wheat heads probably due to an initial delay in the appearance of symptoms.

Identification of candidate genes for Fusarium head blight resistance from QTLs using RIL population in wheat.

Fusarium head blight (FHB) stands out as one of the most devastating wheat diseases and leads to significantly grain yield losses and quality reductions in epidemic years. Exploring quantitative trait loci (QTL) for FHB resistance is a critical step for developing new FHB-resistant varieties. We previously constructed a genetic map of unigenes (UG-Map) according to the physical positions using a set of recombinant-inbred lines (RILs) derived from the cross of 'TN18 × LM6' (TL-RILs). Here, the number of diseased spikelets (NDS) and relative disease index (RDI) for FHB resistance were investigated under four environments using TL-RILs, which were distributed across 13 chromosomes. A number of 36 candidate genes for NDS and RDI from of 19 stable QTLs were identified. The average number of candidate genes per QTL was 1.89, with 14 (73.7%), two (10.5%), and three (15.8%) QTLs including one, two, and 3-10 candidate genes, respectively. Among the 24 candidate genes annotated in the reference genome RefSeq v1.1, the homologous genes of seven candidate genes, including TraesCS4B02G227300 for QNds/Rdi-4BL-4553, TraesCS5B02G303200, TraesCS5B02G303300, TraesCS5B02G303700, TraesCS5B02G303800 and TraesCS5B02G304000 for QNds/Rdi-5BL-9509, and TraesCS7A02G568400 for QNds/Rdi-7AL-14499, were previously reported to be related to FHB resistance in wheat, barely or Brachypodium distachyon. These genes should be closely associated with FHB resistance in wheat. In addition, the homologous genes of five genes, including TraesCS1A02G037600LC for QNds-1AS-2225, TraesCS1D02G017800 and TraesCS1D02G017900 for QNds-1DS-527, TraesCS1D02G018000 for QRdi-1DS-575, and TraesCS4B02G227400 for QNds/Rdi-4BL-4553, were involved in plant defense responses against pathogens. These genes should be likely associated with FHB resistance in wheat.