Aug 2026· Molecular Plant-Microbe Interactions· 0 citations
Medicine
TL;DR
BgtH12 is established as a critical virulence factor that suppresses basal immunity to promote Bgt colonization and stable overexpression of BgtH12 in wheat enhanced susceptibility.
Abstract
The obligate biotrophic fungus Blumeria graminis f. sp. tritici (Bgt), the causal agent of wheat powdery mildew, secretes effector proteins to suppress plant immunity and establish infection. Here, we characterize BgtH12, a conserved small secreted protein that is highly expressed during early infection (peaking at 48 hpi). Functional analysis using host induced gene silencing (HIGS) with two independent fragments achieved 54-82% knockdown of BgtH12 transcripts, resulting in significantly reduced fungal sporulation, hyphal length, and branching. Stable transgenic RNAi lines confirmed these findings, with fungal biomass reduced to 0.6-0.7 fold of the wild type control. Conversely, stable overexpression of BgtH12 in wheat enhanced susceptibility, increasing fungal biomass 4 to 7 fold and accelerating hyphal growth. Histological examination revealed that BgtH12 promotes infection by suppressing early host defense responses: overexpression lines exhibited reduced reactive oxygen species (ROS) accumulation at 24 and 48 hpi, while RNAi lines showed enhanced ROS production. In Nicotiana benthamiana, BgtH12 suppressed BAX triggered cell death, and delivery into wheat cells via the type III secretion system (T3SS) attenuated callose deposition and the ROS burst, indicating broad spectrum suppression of pattern triggered immunity. Subcellular localization assays in wheat protoplasts and N. benthamiana leaves showed that BgtH12 associates with the cell periphery. Together, these results establish BgtH12 as a critical virulence factor that suppresses basal immunity to promote Bgt colonization.
Plant gray mold disease, caused by the necrotrophic fungus Botrytis cinerea, threatens global food security by infecting over 1,400 species. The resistance of B. cinerea to fungicides poses a major challenge for its control. RNA interference (RNAi) shows promise for pathogen management, but high production costs, poor stability, and inefficient delivery of double-stranded RNA (dsRNA) restrict its practical use. In this study, we developed Yarrowia lipolytica strain MP181-2 as a novel RNAi platform, leveraging its ability to colonize the phyllosphere of crop plants (tomato and alfalfa) to enable simultaneous dsRNA production and pathogen targeting via microbe-induced gene silencing (MIGS). Through target screening, we identified three essential fungal genes, BcRpd3, BcNat1, and BcArd1, whose silencing significantly reduced the pathogenicity of B. cinerea. We further constructed a chimeric dsRNA molecule (BcANR-dsRNA) targeting these three genes, which demonstrated superior disease suppression compared to single-gene targeting. The engineered Y. lipolytica strains that produce dsRNA could effectively interfere with the expression of target genes in B. cinerea, and the strain expressing BcANR-dsRNA (designated Yl-dsANR) acquired the ability to suppress the growth of B. cinerea. In planta tests confirmed that Yl-dsANR successfully interfered with the expression of three target genes, leading to decreased fungal biomass and reduced lesion development on different hosts. Notably, foliar application of Yl-dsANR provided durable protection (over 70% efficacy for 5 d) in potted plants. Our integrated approach combines the advantages of microbial biocontrol with RNAi precision, establishing Y. lipolytica as a versatile chassis for sustainable crop protection. This study also provides an effective solution to current limitations in RNA pesticide development and offers a scalable, eco-friendly alternative to chemical fungicides for gray mold management.
Mengjie Liu, Hengshui Shen, Jie Li et al.· Journal of Integrative Plant...· 0 citations
Durum wheat is highly susceptible to Fusarium head blight (FHB) caused by the fungal pathogen Fusarium graminearum. Wheat can be protected with the use of environmentally-friendly and sustainable methods involving biological control agents (BCAs) such as yeasts. However, the mechanism underlying the antagonistic effects of yeasts on plant pathogens has not been fully elucidated. Therefore, the aim of this study was to expand the existing knowledge about the mechanisms of action of a Debaryomyces hansenii biopreparation through transcriptome profiling in F. graminearum cells using RNA sequencing (RNA-seq). The changes in the F. graminearum transcriptome resulting from biotic stress induced by the application of D. hansenii cells to durum wheat spikes, and abiotic stress induced by the application of a cell-free supernatant were compared and comprehensively analyzed. Each stressor elicited a completely different transcriptomic response, and differentially expressed genes (DEGs) encoding metabolic pathways essential for pathogen development associated with carbohydrate and amino acid metabolism, pathogenicity factors, effectors, and secondary metabolites. Numerous transporter genes were also identified, which indicates that fungi exhibit complex responses to biotic and abiotic stresses. The study demonstrated that F. graminearum uses various strategies to overcome the biotic stress associated with BCAs, including the upregulation of the brefeldin A resistance gene (FGSG_02870), which encodes an antifungal compound that inhibits the growth of BCA cells. The present findings provide novel insights into the interactions between pathogens and BCAs with specific mechanisms of action at the transcriptome level, thus helping to explain the relative ineffectiveness of BCAs under certain conditions.
Weronika Giedrojć, W. Pluskota, U. Wachowska· Fungal Genetics and Biology· 0 citations
Wheat Fusarium head blight (FHB) is a globally prevalent and destructive fungal disease predominantly caused by Fusarium graminearum. Pydiflumetofen, a novel succinate dehydrogenase inhibitor (SDHI) fungicide, exhibits strong inhibitory activity against F. graminearum; however, the molecular regulatory mechanisms underlying the field-developed resistance in this pathogen remain poorly defined. In the present study, a field-evolved resistant isolate W24-039 and a sensitive isolate W24-016 were subjected to multi-omics analysis. The sequencing results identified compound mutations C89S/A93V in SdhC2, and A21T/S30F in SdhD of the resistant strain, which confer stable fungicide resistance without any detectable fitness costs. Physiological tests revealed that these target mutations sustain the homeostasis of succinate dehydrogenase (SDH) activity and intracellular ATP production. Following pydiflumetofen treatment, the sensitive isolate displayed remarkable declines in SDH activity, intracellular ATP content and deoxynivalenol (DON) biosynthesis, accompanied by markedly elevated cell membrane permeability. Transcriptomic sequencing uncovered 2221 differentially expressed genes (DEGs) in the sensitive strain under fungicide stress, and 2566 DEGs in the resistant isolate under the same conditions. The genes associated with detoxification and drug efflux, including cytochrome P450, glutathione S-transferase (GST), ABC and MFS transporters, were significantly upregulated in the resistant isolate. Metabolomic analysis indicated that differential metabolites were mainly enriched in the tricarboxylic acid (TCA) cycle, amino acid metabolism and membrane lipid biosynthesis pathways. The resistant strain maintained intact TCA cycle operation and accumulated high levels of pivotal metabolites such as phosphatidylcholine, unsaturated fatty acids and reduced glutathione. Integrated multi-omics analysis verified that the ABC transporter and glutathione metabolism pathways serve as core regulatory modules governing fungicide resistance. Collectively, F. graminearum develops resistance via the synergistic effects of SDH compound mutations, enhanced detoxification and efflux, and global metabolic remodeling, demonstrating that target-site mutation alone is not the sole driver of resistance, which is instead controlled by an intricate regulatory network involving multiple coordinated pathways. This study systematically characterizes the resistance regulatory network of F. graminearum against pydiflumetofen, and provides theoretical guidance for the rational application and sustainable field resistance management of this fungicide.
Yun Wang, Dongmei Liu, Haiyan Yin et al.· International Journal of Mol...· 0 citations
Verticillium dahliae is a devastating soil-borne fungal pathogen that causes severe yield losses in melon (Cucumis melo L.) and other crops. Identifying novel resistance genes is crucial for sustainable disease management. In this study, we characterized the function of CmVQ23, a candidate gene previously identified through QTL mapping, in mediating defense against V. dahliae using heterologous expression in Arabidopsis thaliana. Subcellular localization assays revealed that the CmVQ23-eGFP fusion protein predominantly localized to the nucleus, consistent with its predicted role as a co-factor of transcription factor. Upon V. dahliae inoculation, CmVQ23-overexpressing Arabidopsis lines exhibited significantly reduced disease indices and restricted fungal proliferation compared with wild-type and mutant plants, although these lines displayed altered vegetative growth, including delayed bolting and reduced plant height. Mechanistically, CmVQ23 overexpression promoted reactive oxygen species (ROS) accumulation and hypersensitive response (HR)-mediated cell death at infection sites, as evidenced by intensified DAB and trypan blue staining. Furthermore, transgenic lines maintained higher photosynthetic efficiency, enhanced antioxidant enzyme activities, and increased lignin deposition via upregulation of phenylalanine ammonia-lyase (PAL) and polyphenol oxidase (PPO). Notably, CmVQ23 overexpression markedly upregulated both salicylic acid (SA)- and jasmonic acid/ethylene (JA/ET)-responsive marker genes, including AtPR1, AtPR2, AtPR5, AtPAD4, AtPDF1.2, and AtVSP2 upon infection. Collectively, these findings demonstrate that CmVQ23 functions as a positive regulator of resistance to Verticillium dahliae by orchestrating ROS/HR-mediated cell death, antioxidant defense, phenylpropanoid pathway activation, and phytohormone signaling crosstalk, offering a promising genetic resource for improving Verticillium wilt resistance in crops.
Together, these findings identify PtGH1and PtCBM1 as distinct virulence factors that act through complementary mechanisms, involving physical facilitation and enzymatic degradation of host cell walls, illustrating how the leaf rust fungus overcomes host immunity and provides potential molecular targets for developing durable wheat resistance.
Yanan Lu, Keyan Wu, Jinyang Li et al.· Phytopathology Research· 0 citations
Engineering broad‐spectrum disease resistance remains a major challenge in crop improvement because most resistance genes are effective against a limited range of pathogens. Pathogenesis‐related (PR) proteins, particularly endochitinases, are promising targets for enhancing plant immunity due to their antimicrobial activity and ability to activate defense responses. Here, we generated transgenic tomato (Solanum lycopersicum L.) plants overexpressing an endochitinase gene to assess their potential for enhanced resistance against bacterial and fungal pathogens. Three independent overexpression lines and the wild type were evaluated for transgene expression, chitinase activity, defense‐related gene expression, and resistance after inoculation with Xanthomonas euvesicatoria pv. perforans (Xep) and Sclerotinia sclerotiorum. The transgene was strongly expressed in all transgenic lines, whereas chitinase activity increased by up to fivefold compared with the wild type. Endochitinase overexpression activated defense responses, with marked induction of PR1 expression, reaching a maximum increase of over 480‐fold, and enhanced expression of defense‐associated genes, including SlACS and SlACO. Compared with the wild type, the most responsive transgenic lines showed reductions of up to 79.7% in bacterial spot severity and 85.6% in white mold severity. These findings demonstrate that endochitinase overexpression activates defense signaling and improves broad‐spectrum resistance, representing a promising strategy for developing disease‐resistant tomato cultivars.
Lucas José de Sousa, A. C. Bezerra, Ivonaldo Reis Santos et al.· Biotechnology Journal· 0 citations
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