Plant disease最新文献

Fusarium Head Blight (FHB) can result in severe blighting of hemp grain and floral tissues. A multi-site field trial was conducted in 2022 and 2023 that included 3 different hemp cultivars with varying flowering time (early-, mid-, and late-flowering) and eight planting dates to detect and quantify early infection by F. graminearum. Asymptomatic terminal buds, female flowers, and/or male flowers were collected every 2 weeks beginning 2 to 3 weeks after planting and continuing until FHB symptoms were observed or plants reached maturity, resulting in 10 to 12 sampling dates per field. To detect and quantify F. graminearum, samples were subjected to a species-specific qPCR assay. Treatments including planting date and cultivar resulted in different levels of latent infection in each year and at each location. Despite latent infection being observed in vegetative tissues, infection was more prominent during flowering stages, indicating the importance of flowers for infection. Detections also appeared to be related to environmental factors such as rain and relative humidity. FHB symptoms were commonly observed 6 to 8 weeks after initial detection. Determination of when F. graminearum infection occurs in the field will help identify critical FHB management windows for hemp producers.

Pectobacterium carotovorum is a gram-negative phytopathogenic bacterium that causes soft rot disease on diverse plant species. It encodes the type III secretion system effector protein, DspE, and its chaperone, DspF. The DspE family proteins form water and solute channels in plant cells, flooding the apoplast to aid bacterial multiplication. In Pseudomonas syringae, the DspE ortholog, AvrE, upregulates abscisic acid (ABA) expression, leading to stomatal closure. In this study, a Pectobacterium carotovorum dspEF mutant did not cause leaf cell death in tobacco leaves. This observation is supported by the lower expression of PCWDE such as pelB, pelI, celV, prtW, and the quorum sensing system transcript expI in tobacco plants prior to visual symptoms (5 hours post-inoculation). Interestingly, neither dspE/F or hrpL mutation affected synthesis of QS signaling molecule AHL under microbiological settings. However, maceration symptoms occurred if leaves infiltrated with the dspEF mutant were kept under high humidity or detached post-infiltration. These leaves showed elevated transcription of ABA synthesis genes compared to infiltrated leaves maintained on the plant under ambient conditions. To validate this involvement, co-infiltration of ABA with the dspEF mutant restored its ability to cause maceration in attached leaves under ambient conditions. Overall, our data suggest that DspE/F facilitates host susceptibility by creating an aqueous apoplast, promoting ABA accumulation and stomata closure.

Wolfberry (Lycium barbarum) is an important economic crop with extremely high medicinal value; however, root rot disease leads to a serious decline in the yield and quality of wolfberry. In this study, we used one-year-old wolfberry seedlings as test material to explore the control effect of single or combined inoculation with arbuscular mycorrhizal (AM) fungus Rhizophagus intraradices and endophytic fungus Metarhizium robertsii on wolfberry root rot and preliminarily probed the related disease resistance mechanisms. The results showed that both R. intraradices and M. robertsii could successfully colonize the roots of wolfberry, and the combined inoculation significantly increased the colonization rate of R. intraradices and reduced the incidence of wolfberry root rot, with a control effect of 68%. Combined inoculation enables plants to absorb nitrogen and phosphorus more effectively by increasing the nutrient uptake area and activity of wolfberry roots, which helps to increase chlorophyll content and promote plant growth. It also improved the resistance of wolfberry to root pathogens by regulating endogenous hormones (significantly increasing the contents of salicylic acid, indole-3-acetic acid, gibberellin A3, and decreasing the content of abscisic acid) and enhancing defensive enzyme activities (superoxide dismutase, peroxidase, and ascorbate peroxidase). In terms of soil, the combined inoculation significantly increased the nitrogen content and enzyme activities (sucrase, urease, and catalase), creating a more favorable growth environment for wolfberry. In conclusion, AM fungus R. intraradices combined with endophytic fungus M. robertsii can effectively enhance the disease resistance of wolfberry to root rot and has certain biocontrol application potential (Graphical abstract).

Potentilla anserina L. is widely recognized for its extensive applications in traditional medicine and as a food source, harboring abundant bioactive compounds that confer significant medicinal and economic value. However, a severe disease consisting of leaf spots has adversely impacted P. anserina yield and quality in Heilongjiang Province, China. This study aims to identify the causal agent(s) of the disease, characterize the pathogen(s), and screen for effective control means. A total of 128 isolates were obtained from spotted leaves of P. anserina, with Alternaria tenuissima accounting for 68.7% and A. alternata for 32.3% of the isolates. These species were identified according to morpho-molecular characteristics and phylogenetic analyses. According to pathogenicity tests, A. alternata and A. tenuissima are both highly pathogenicity to P. anserina. In addition, all isolates were highly pathogenic to Astragalus laxmannii, Glycyrrhiza uralensis, and Trifolium pratense, moderately pathogenic to Artemisia argyi，and Beta vulgaris, and did not infect Mentha canadensis, Glycine max, Arachis hypogaea or Capsicum annuum. The isolates of A. alternata and A. tenuissima exhibited high sensitivity to benzoxystrobin and the biological control agent Paenibacillus polymyxa, with EC50 and IC50 values ranging from 0.09 to 0.57 µg/ml and 0.07 to 0.12 mg/ml, respectively. The efficacies varied between 96.1% and 97.5% at 480 μg/ml and between 95.1% and 97.1% at 240 mg/ml, respectively. According to this study, the pathogens responsible for P. anserina leaf spot in Heilongjiang, China, are A. tenuissima and A. alternata. Both showed high pathogenicity, but were effectively controlled by benzoxystrobin and Paenibacillus polymyxa, suggesting chemical treatments, intercropping and biocontrol as management strategies.

Monilinia fructicola, the most widely distributed species among the Monilinia genus globally, causes blossom blight, twig canker, and fruit rot on Rosaceae fruits. Despite previous studies, limitations still exist regarding virulence of M. fructicola. In this study, we identified a gene significantly upregulated during the early stages of infection. Bioinformatic analysis revealed that this gene encoded a protein containing the HAD_SAK_1 domain (abbreviated as HS1), and we named it MfHS1. Knockout and complemented transformants were generated and evaluated for environmental fitness. Results revealed that MfHS1 was involved in the regulation of osmotic stress and cell wall integrity. Additionally, microscopic observations showed that MfHS1 participated in the differentiation process of hyphal tips. Virulence assays indicated that the knockout transformant ΔMfHS1 exhibited significantly reduced virulence. Considering that MfHS1 is predicted as a non-classical secreted protein, it was transiently expressed in Nicotiana benthamiana leaves, and the induced plant cell death was observed, indicating that MfHS1 might trigger plant defense responses, e.g., programmed cell death, and supply nutrients to necrotic pathogens, thus aiding host infection. This study offers a new perspective for further understanding the pathogenic mechanisms of M. fructicola and developing control strategies.

The widespread emergence of fungicide-resistant Botrytis cinerea populations, together with increasingly strict regulatory constraints, has intensified the need for alternative and environmentally sustainable strategies for gray mold management. This study evaluates spray-induced gene silencing (SIGS) targeting mitochondrial respiration through double-stranded RNAs (dsRNAs) directed against sdhB and cytB genes. These genes encode key subunits of respiratory complexes II and III, key targets and determinants of resistance to SDHI and QoI fungicides, respectively. Exogenous application of these dsRNAs significantly reduced B. cinerea conidial germination (~50%), lesion development in tomato leaves and apple fruits (~45%), fungal biomass (~50%), and transcript levels of sdhB (3.2-fold) and cytB (2.0-fold). When combined with sublethal doses of boscalid (SDHI) or azoxystrobin (QoI), dsRNA treatments markedly decreased lesion severity in fungicide-sensitive isolates, achieving substantial but not full equivalent to field-dose fungicide efficacy. In resistant isolates, dsRNA alone consistently reduced disease symptoms, and its combination with sublethal-dose fungicides further enhanced control. When dsRNA was applied together with full-rate fungicide, lesion development declined sharply across all resistant isolates, and in some cases gray mold symptoms were completely eradicated, indicating the strong biological effect achieved by the RNAi-fungicide combination. Sequence identity analyses revealed strong cross-species activity among closely related Botrytis and Sclerotiniaceae species, with no predicted effects on unrelated fungi, plants, or humans. This work provides the first demonstration of a dual-target SIGS strategy acting on mitochondrial respiration, highlighting its potential as a precise, eco-compatible, and effective tool for managing B. cinerea resistance within integrated pest management frameworks.

Pythium soft rot in ginger is caused by Pythium myriotylum, leading to significant reductions in ginger yields. In this study, a loop-mediated isothermal amplification (LAMP) detection method was established for Py. myriotylum in infected ginger plants and infested soil. The Py. myriotylum genome was compared with the genomes of seven additional oomycete species to obtain species-specific sequences. LAMP primer sets were designed and assessed at temperatures from 58°C to 68°C and tested for their specificity. Furthermore, the sensitivity of the screened primer set was evaluated, and the detection limit was 1 pg of Py. myriotylum genomic DNA (gDNA) in a 25-µl reaction volume. LAMP was used to detect Py. myriotylum zoospores in solution (1×10²/ml), vermiculite (1×10²/g), and soil (1×10⁴/g). A rapid and portable gDNA extraction method from ginger seedlings and rhizomes using solid-phase reversible immobilization beads for purification was adopted. The LAMP assay could reliably detect Py. myriotylum in artificially inoculated diseased ginger seedlings and rhizosphere vermiculite. The portable gDNA extraction method coupled with the LAMP assay facilitates point-of-care pathogen detection, requiring 2 to 3 hours for eight samples, greatly reducing the time needed for Py. myriotylum detection of Pythium soft rot in ginger.

Luffa acutangula and Momordica charantia, known for their edible and medicinal value, are economically important cucurbitaceous vegetable crops cultivated globally. Gummy stem blight, primarily caused by Stagonosporopsis species, is a devastating disease on cucurbits, resulting in significant economic losses. Although occurrence of gummy stem blight on L. acutangula and M. charantia has been reported previously, the pathogen responsible for the disease on these two crops has not been clearly identified because of the taxonomical nomenclature changes. During the period from 2018 to 2024, diseases resembling gummy stem blight were commonly observed on L. acutangula and M. charantia in Guangdong Province of China, with a disease incidence for L. acutangula of 13.5 to 21.7% in Guangzhou and 13.5 to 25.0% in Huizhou and a disease incidence for M. charantia of 20.0 to 30.0% in Guangzhou and 16.7 to 26.7% in Huizhou. Samples of symptomatic leaves, stems, and fruits were collected, and 52 fungal isolates with similar colony morphology were obtained. The initial identification of these isolates was based on cultural and morphological characteristics, which placed them in Stagonosporopsis. Subsequently, they were identified as S. citrulli with multilocus phylogenetic analyses using the ribosomal DNA internal transcribed spacer and portions of the β-tubulin, chitin synthase I, and calmodulin genes. Pathogenicity tests were conducted on leaves and fruits of L. acutangula, M. charantia, and Cucumis sativus with representative isolates of S. citrulli. These isolates produced lesion symptoms on L. acutangula and M. charantia similar to the disease symptoms in the field. Furthermore, they were also pathogenic to C. sativus. The same pathogen was reisolated from lesions of inoculated plants to fulfill Koch's postulates. To our knowledge, this study is the first report identifying S. citrulli as the causal agent of gummy stem blight on L. acutangula and M. charantia in China.

Fusarium dry rot (FDR) is a major postharvest disease of potatoes, causing significant economic losses worldwide. This study investigated the morphological and molecular diversity of Fusarium species causing dry rot in the San Luis Valley (SLV), Colorado. Potato tubers exhibiting characteristic dry rot symptoms were sampled during the 2023 and 2024 growing seasons. Fusarium species were isolated, characterized morphologically and molecularly, and identified as Fusarium oxysporum, F. sambucinum, F. clavum, and F. solani. Colony morphology, macroconidia, microconidia, and chlamydospore formation were analyzed to classify isolates into four distinct groups. Molecular characterization using internal transcribed spacer, rpb2, and tef markers confirmed species identity, supported by sequencing and phylogenetic analysis that grouped isolates into well-defined clades. Radial growth assessments demonstrated significant differences among species over time, with F. sambucinum exhibiting the fastest growth. Pathogenicity assays on three potato cultivars revealed varying virulence, with F. solani causing the most severe infections in cultivars tested. This study represents the first documented occurrence of F. oxysporum, F. sambucinum, F. clavum, and F. solani as causal agents of FDR in Colorado. Furthermore, F. clavum is a novel species associated with potato dry rot, not previously reported in the United States. The integration of molecular and traditional techniques underscores the genetic and morphological diversity of Fusarium spp. in the SLV and highlights their pathogenic potential. These findings provide a foundation for future research to mitigate the economic impacts of FDR and ensure the viability of potato production in Colorado and beyond.

Xylella fastidiosa (Xf) is a quarantine plant pathogen in the European Union, recognized as a high-priority pest due to its devastating cultural and economic impact on crops, ornamental plants, and landscape vegetation. The development and implementation of reliable, sensitive, and specific diagnostic methods for Xf detection are critical to ensure the production and trade of healthy plant material and to facilitate effective control measures, primarily aimed at eradication. Despite the availability of numerous detection protocols, their diagnostic parameters remain not precisely defined, and no universally accepted gold standard protocol exists. This study compared the global accuracy and performance of six molecular assays using almond samples collected from naturally infected almond trees in the Alicante Demarcated Area, Spain. Additionally, the study evaluated the influence of plant sample type (leaf petioles versus woody chips) on diagnostic accuracy. Harper-qPCR and Li-qPCR assays demonstrated the highest sensitivity, with detection limits as low as 2.8 to 3 fg of Xf DNA. Droplet digital PCR (ddPCR) exhibited excellent sensitivity for woody chip samples, while Li-qPCR showed superior specificity across both tissue types. In contrast, recombinase polymerase amplification displayed lower detection limits and reproducibility compared with qPCR-based methods. Bayesian latent class models indicated that combining Harper-qPCR and Li-qPCR for petioles, or Harper-qPCR and ddPCR for wood samples, optimized diagnostic reliability by reducing false negatives, which is critical in buffer zones under eradication while maintaining high specificity. These findings emphasize the need for tailoring diagnostic protocols to the epidemiological context, balancing sensitivity and specificity to optimize surveillance schemes for Xf and to support effective phytosanitary management strategies.[Formula: see text] Copyright © 2026 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.