Barley Resistance to Fusarium graminearum Infections: From Transcriptomics to Field with Food Safety Concerns

Design, synthesis, and antifungal activity of novel pyrazole carboxamide derivatives containing benzimidazole moiety as potential SDH inhibitors

To address the urgent need for new antifungal agents, a collection of novel pyrazole carboxamide derivatives incorporating a benzimidazole group were innovatively designed, synthesized, and evaluated for their efficacy against fungal pathogens. The bioassay results revealed that the EC50 values for the compounds A7 (3-(difluoromethyl)-1-methyl-N-(1-propyl-1H-benzo[d]imidazol-2-yl)-1H-pyrazole-4-carboxamide) and B11 (N-(1-(4-chlorobenzyl)-1H-benzo[d]imidazol-2-yl)-3-(difluoromethyl)-1-methyl-1H-pyrazole-4-carboxamide) against B. cinerea were notably low to 0.79 µg/mL and 0.56 µg/mL, respectively, demonstrating the potency comparable to that of the control fungicide boscalid, which has an EC50 value of 0.60 µg/mL. Noteworthy is the fact that in vivo tests demonstrated that A7 and B11 showed superior protective effects on tomatoes and strawberries against B. cinerea infection when juxtaposed with the commercial fungicide carbendazim. The examination through scanning electron microscopy revealed that B11 notably alters the morphology of the fungal mycelium, inducing shrinkage and roughening of the hyphal surfaces. To elucidate the mechanism of action, the study on molecular docking and molecular dynamics simulations was conducted, which suggested that B11 effectively interacts with crucial amino acid residues within the active site of succinate dehydrogenase (SDH). This investigation contributes a novel perspective for the structural design and diversification of potential SDH inhibitors, offering a promising avenue for the development of antifungal therapeutics.

Design, Synthesis, and Anti-Oomycete and Antifungal Activities of Novel Paeonol Derivatives Containing a Pyrazole Ring

Paeonol is the main active ingredient in the Chinese medicinal herb peony root bark. To discover biorational natural product-based fungicides, 25 paeonol derivatives (5a-y) containing a pyrazole ring were designed and synthesized by ingeniously introducing a pyrazole five-membered heterocyclic ring, and their structures were well characterized by 1H NMR, 13C NMR, high-resolution mass spectrometer (HRMS), and m.p. The stereochemical configurations of six target compounds, 5c, 5f, 5g, 5o, 5s, and 5v, were unambiguously subjected to single-crystal X-ray diffraction. Furthermore, we evaluated the bioactivities of these target compounds as anti-oomycete and antifungal agents against two serious agricultural diseases, Phytophthora capsici and Fusarium graminearum. Among all tested compounds, (1) nine compounds 5b-d, 5f, 5g, 5r, 5s, 5u, 5w displayed promising anti-oomycete against P. capsici, with EC50 values ranging from 22.1 to 34.5 mg/L, and the protective effect of the target compounds against P. capsici in vivo further confirmed the above results. (2) Six compounds 5g, 5k, 5m, 5t, 5w, 5x displayed promising antifungal against F. graminearum, with EC50 values ranging from 38.2 to 86.0 mg/L. Moreover, some interesting results of structure-activity relationships were also observed. The results of this study pave the way for further design, synthesis, and development of paeonol derivatives as potential botanical anti-oomycete and antifungal agents in crop protection.

Triple Threat: How Global Fungal Rice and Wheat Pathogens Utilize Comparable Pathogenicity Mechanisms to Drive Host Colonization

Plant pathogens pose significant threats to global cereal crop production, particularly for essential crops such as rice and wheat, which are fundamental to global food security and provide nearly 40% of the global caloric intake. As the global population continues to rise, increasing agricultural production to meet food demands becomes even more critical. However, the production of these vital crops is constantly threatened by phytopathological diseases, especially those caused by fungal pathogens such as Magnaporthe oryzae, the causative agent of rice blast disease; Fusarium graminearum, responsible for Fusarium head blight in wheat; and Zymoseptoria tritici, the source of Septoria tritici blotch. All three pathogens are hemibiotrophic, initially colonizing the host through a biotrophic, symptomless lifestyle, followed by causing cell death through the necrotrophic phase. Additionally, they deploy a diverse range of effectors, including proteinaceous and non-proteinaceous molecules, to manipulate fundamental host cellular processes, evade immune responses, and promote disease progression. This review discusses recent advances in understanding the effector biology of these three pathogens, highlighting both the shared functionalities and unique molecular mechanisms they employ to regulate conserved elements of host pathways, such as directly manipulating gene transcription in host nuclei, disrupting reactive oxygen species signaling, interfering with protein stability, and undermining host structural integrity. By detailing these complex interactions, the review explores potential targets for innovative control measures and emphasizes the need for further research to develop effective strategies against these destructive pathogens in the face of evolving environmental and agricultural challenges. [Formula: see text] Copyright © 2025 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Enhancing tiny millets through genome editing: current status and future prospects

This study aims to address the critical need for genetic improvement of small millets, which are vital yet underutilized cereal crops cultivated in semi-arid regions of Africa and Asia. Given their high nutritional value and climate resilience, small millets hold significant potential for food security and sustainable agriculture in arid regions. However, traditional breeding methods have proven to be time-consuming and inefficient in enhancing desirable traits. This study highlights the transformative potential of genome editing technologies, particularly the CRISPR/Cas9 system, in accelerating the development of improved small millet varieties. The findings presented in this paper detail recent advancements in using CRISPR/Cas for enhancing resistance to biotic stresses, including bacterial, viral, and fungal pathogens. Additionally, we explore how genome editing can be applied to improve abiotic stress tolerance, addressing challenges such as drought, cold, heat, and herbicides in small millets. We discuss the existing challenges faced by breeders, including issues related to ploidy levels, off-target effects, and limitations in organelle genome modification. The review also suggests potential strategies for overcoming these bottlenecks, aiming to develop stress-resistant super cultivars. Overall, this paper provides an overview of the current state of genome editing research in small millets while identifying future opportunities to enhance key traits for nutrient enrichment and climate resilience, ultimately paving the way for advancements in these crucial crops.

Salicylic Acid Mediates Chitosan-Induced Immune Responses and Growth Enhancement in Barley

Chitosan (CS), derived from the partial deacetylation and hydrolysis of chitin, varies in the degree of deacetylation, molecular weight, and origin, influencing its biological effects, including antifungal properties. In plants, CS triggers immune responses and stimulates biomass growth. Previously, we found that the antifungal activity of CS was strongly dependent on its physicochemical properties. This study revealed that the chitosan batch CS_10 with the strongest antifungal activity also effectively activated plant immune responses and promoted biomass growth. Barley treated with CS_10 exhibited systemic acquired resistance (SAR), characterized by micronecrotic reactions upon Puccinia hordei (Ph) inoculation and reduced symptoms following Fusarium graminearum (Fg) infection, representing biotrophic and necrotrophic pathogens, respectively. CS_10 treatment (concentration 200 ppm) also enhanced plant biomass growth (by 11% to 15%) and promoted the accumulation of salicylic acid (SA), a hormone that regulates both plant immune responses and growth. Low levels of exogenous SA applied to plants mirrored the stimulation observed with CS_10 treatment, suggesting SA as a key regulator of CS_10-induced responses. Transcriptomic analysis identified SA-regulated genes as drivers of enhanced immunity and biomass stimulation. Thus, CS_10 not only fortifies plant defenses against pathogens like Ph and Fg but also boosts growth through SA-dependent pathways.

BW312 Hordeum vulgare semi-dwarf mutant exhibits a shifted metabolic profile towards pathogen resistance

INTRODUCTION

Plant hormonal mutants, which do not produce or are insensitive to hormones, are often affected in their growth and development, but other metabolic rearrangements might be involved. A trade-off between growth and stress response is necessary for the plant survival.

OBJECTIVES

Here, we explore the metabolic profile and the pathogen resistance of a brassinosteroid-insensitive Hordeum vulgare L. semi-dwarf mutant, BW312.

METHODS

We investigate BW312 metabolism through a chemical enrichment analysis, confirming a shifted metabolic profile towards pathogen resistance. The effective pathogen resistance of the mutant was tested in presence of Pyrenophora teres and Fusarium graminearum.

RESULTS

Four compound families were increased in the mutant (pyrrolidines, basic amino acids, alkaloids, monounsaturated fatty acids), while two compound families were decreased (pyrrolidinones, anthocyanins). Dipeptides were also altered (increased and decreased). BW312 displayed a better resistance to Pyrenophora teres in the earliest stage of infection with a 21.5% decrease of the lesion length 10 days after infection. BW312 also exhibited a reduced lesion length (43.3%) and a reduced browning of the lesions (55.5%) when exposed to Fusarium graminearum at the seedling stage.

CONCLUSION

The observed metabolomic shift strongly suggests that the BW312 semi-dwarf mutant is in a primed state, resulting in a standby state of alertness to pathogens.

Controlled Environment Ecosystem: A Cutting-Edge Technology in Speed Breeding

The controlled environment ecosystem is a meticulously designed plant growing chamber utilized for cultivating biofortified crops and microgreens, addressing hidden hunger and malnutrition prevalent in the growing population. The integration of speed breeding within such controlled environments effectively eradicates morphological disruptions encountered in traditional breeding methods such as inbreeding depression, male sterility, self-incompatibility, embryo abortion, and other unsuccessful attempts. In contrast to the unpredictable climate conditions that often prolong breeding cycles to 10-15 years in traditional breeding and 4-5 years in transgenic breeding within open ecosystems, speed breeding techniques expedite the achievement of breeding objectives and F1-F6 generations within 2-3 years under controlled growing conditions. In comparison, traditional breeding may take 5-10 years for plant population line creation, 3-5 years for field trials, and 1-2 years for variety release. The effectiveness of speed breeding in trait improvement and population line development varies across different crops, requiring approximately 4 generations in rice and groundnut, 5 generations in soybean, pea, and oat, 6 generations in sorghum, Amaranthus sp., and subterranean clover, 6-7 generations in bread wheat, durum wheat, and chickpea, 7 generations in broad bean, 8 generations in lentil, and 10 generations in Arabidopsis thaliana annually within controlled environment ecosystems. Artificial intelligence leverages neural networks and algorithm models to screen phenotypic traits and assess their role in diverse crop species. Moreover, in controlled environment systems, mechanistic models combined with machine learning effectively regulate stable nutrient use efficiency, water use efficiency, photosynthetic assimilation product, metabolic use efficiency, climatic factors, greenhouse gas emissions, carbon sequestration, and carbon footprints. However, any negligence, even minor, in maintaining optimal photoperiodism, temperature, humidity, and controlling pests or diseases can lead to the deterioration of crop trials and speed breeding techniques within the controlled environment system. Further comparative studies are imperative to comprehend and justify the efficacy of climate management techniques in controlled environment ecosystems compared to natural environments, with or without soil.

Antifungal potential of lipopeptides produced by the Bacillus siamensis Sh420 strain against Fusarium graminearum

Biological control is a more sustainable and environmentally friendly alternative to chemical fungicides for controlling Fusarium spp. infestations. In this work, Bacillus siamensis Sh420 isolated from wheat rhizosphere showed a high antifungal activity against Fusarium graminearum as a secure substitute for fungicides. Sh420 was identified as B. siamensis using phenotypic evaluation and 16S rDNA gene sequence analysis. An in vitro antagonistic study showed that Sh420's lipopeptide (LP) extract exhibited strong antifungal properties and effectively combated F. graminearum. Meanwhile, lipopeptides have the ability to decrease ergosterol content, which has an impact on the overall structure and stability of the plasma membrane. The PCR-based screening revealed the presence of antifungal LP biosynthetic genes in this strain's genomic DNA. In the crude LP extract of Sh420, we were able to discover several LPs such as bacillomycin, iturins, fengycin, and surfactins using ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry. Microscopic investigations (fluorescent/transmission electron microscopy) revealed deformities and alterations in the morphology of the phytopathogen upon interaction with LPs. Sh420 LPs have been shown in grape tests to be effective against F. graminearum infection and to stimulate antioxidant activity in fruits by avoiding rust and gray lesions. The overall findings of this study highlight the potential of Sh420 lipopeptides as an effective biological control agent against F. graminearum infestations.IMPORTANCEThis study addresses the potential of lipopeptide (LP) extracts obtained from the strain identified as Bacillus siamensis Sh420. This Sh420 isolate acts as a crucial player in providing a sustainable and environmentally friendly alternative to chemical fungicides for suppressing Fusarium graminearum phytopathogen. Moreover, these LPs can reduce ergosterol content in the phytopathogen influencing the overall structure and stability of its plasma membrane. PCR screening provided confirmation regarding the existence of genes responsible for biosynthesizing antifungal LPs in the genomic DNA of Sh420. Several antibiotic lipopeptide compounds were identified from this bacterial crude extract using ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry. Microscopic investigations revealed deformities and alterations in the morphology of F. graminearum upon interaction with LPs. Furthermore, studies on fruit demonstrated the efficacy of Sh420 LPs in mitigating F. graminearum infection and stimulating antioxidant activity in fruits, preventing rust and gray lesions.

Investigating Metabolic Plant Response toward Deoxynivalenol Accumulation in Four Winter Cereals

Deoxynivalenol (DON) is a phytotoxic agent supporting the spread of fungal diseases in cereals worldwide, i.e., fusarium head blight. It is known that DON accumulation may elicit changes in plant secondary metabolites in response to pathogen attack. This study maps the changes in selected secondary metabolite classes upon DON contamination occurring in fifteen Triticum spp. genotypes, among them emmer, spelt, and soft wheat, and 2 tritordeum varieties, cultivated in two different sites and over two harvest years. The main phenolic classes (i.e., alkylresorcinols, soluble, and cell-wall bound phenolic acids) were targeted analyzed, while changes in the lipidome signature were collected through untargeted HRMS experiments. The results, obtained across multiple Triticum species and in open fields, confirmed the modulation of first-line biological pathways already described in previous studies involving single cereal species or a limited germplasm, thus reinforcing the involvement of nonspecific chemical defenses in the plant response to pathogen attack.

Barley shows reduced Fusarium head blight under drought and modular expression of differentially expressed genes under combined stress

Plants often face simultaneous abiotic and biotic stress conditions; however, physiological and transcriptional responses under such combined stress conditions are still not fully understood. Spring barley (Hordeum vulgare) is susceptible to Fusarium head blight (FHB), which is strongly affected by weather conditions. We therefore studied the potential influence of drought on FHB severity and plant responses in three varieties of different susceptibility. We found strongly reduced FHB severity in susceptible varieties under drought. The number of differentially expressed genes (DEGs) and strength of transcriptomic regulation reflected the concentrations of physiological stress markers such as abscisic acid or fungal DNA contents. Infection-related gene expression was associated with susceptibility rather than resistance. Weighted gene co-expression network analysis revealed 18 modules of co-expressed genes that reflected the pathogen- or drought-response in the three varieties. A generally infection-related module contained co-expressed genes for defence, programmed cell death, and mycotoxin detoxification, indicating that the diverse genotypes used a similar defence strategy towards FHB, albeit with different degrees of success. Further, DEGs showed co-expression in drought- or genotype-associated modules that correlated with measured phytohormones or the osmolyte proline. The combination of drought stress with infection led to the highest numbers of DEGs and resulted in a modular composition of the single-stress responses rather than a specific transcriptional output.

Germination and First Stages of Growth in Drought, Salinity, and Cold Stress Conditions of Plasma-Treated Barley Seeds

Numerous works have demonstrated that cold plasma treatments constitute an effective procedure to accelerate seed germination under nonstress conditions. Evidence also exists about a positive effect of plasmas for germination under environmental stress conditions. For barley seeds, this work studies the influence of cold plasma treatments on the germination rate and initial stages of plant growth in common stress environments, such as drought, salinity, and low-temperature conditions. As a general result, it has been found that the germination rate was higher for plasma-treated than for untreated seeds. Plasma also induced favorable changes in plant and radicle dimensions, which depended on the environment. The obtained results demonstrate that plasma affects the biochemical metabolic chains of seeds and plants, resulting in changes in the concentration of biochemical growing factors, a faster germination, and an initially more robust plant growth, even under stress conditions. These changes in phenotype are accompanied by differences in the concentration of biomarkers such as photosynthetic pigments (chlorophylls a and b and carotenoids), reactive oxygen species, and, particularly, the amino acid proline in the leaves of young plants, with changes that depend on environmental conditions and the application of a plasma treatment. This supports the idea that, rather than an increase in seed water imbibition capacity, there are clear beneficial effects on seedling of plasma treatments.

Low Molecular Weight and High Deacetylation Degree Chitosan Batch Alleviates Pathogenesis, Toxin Accumulation, and Fusarium Gene Regulation in Barley Leaf Pathosystem

Fusarium graminearum is a cosmopolitan fungal pathogen that destroys cereal production, in terms of loss of yield and grain contamination with mycotoxins, worldwide. Chitosan is a natural biopolymer abundant in the environment with proven antifungal properties that also acts as a plant immunity elicitor. Despite a number of articles, there is a lack of systematic comparison of antifungal activity of diverse batches of chitosan. The current study aimed to test the inhibitory effects of a collection of diverse chitosan samples on the growth and production of F. graminearum toxins, validated by changes in the Fusarium transcriptome. Experiments included testing antifungal activity of different chitosan samples, the application of the best performing one in vitro to investigate the impact on F. graminearum growth, followed by analyzing its effect on Fusarium toxins accumulation, and Fusarium transcriptomics in the barley leaf pathosystem. Confirmatory antifungal assays revealed that CS_10, a specific batch of chitosan, retarded Fusarium growth with an application concentration of 200 ppm, significantly reducing toxin synthesis and disease symptoms in Fusarium-inoculated barley leaves. RNA-Seq analysis of F. graminearum in barley leaf pathosystem exposed to CS_10 showed a list of differentially expressed genes involved in redox balance, cell respiration, nutrient transport, cell wall degradation enzymes, ergosterol biosynthesis, and trichothecenes production. The genes functioning in these essential pathways are discussed and assigned as critical checkpoints to control Fusarium infections. The results suggest some important molecular targets in F. graminearum that may be suitable in gene-specific targeting or transgene-free methods, such as spray-induced gene silencing during host-pathogen interactions.