European Journal of Plant Pathology最新文献

Potato (Solanum tuberosum) is one of the most important crops facing threats from different diseases. Rapid and accurate diagnosis is essential to control disease development and spread. Quantitative real-time PCR (qRT-PCR) has been widely used in potato disease diagnosis. In this study, we evaluated the specificity of 19 probe-based and four SYBR Green-based qPCR protocols for 17 potato diseases using in silico analysis. Primers and probes of those protocols were subjected to BLASTn analysis against the nucleotide collection (nr/nt) database and the whole-genome shotgun contigs (wgs) database of NCBI for the presence of primer/probe sequences in non-target species. Results showed that 12 of 23 qPCR protocols were not specific to the target pathogens. A qPCR experiment indicated that even nine single nucleotide polymorphisms (SNPs) are present on the sequences of the primer/probe binding sites between the potato silver scurf pathogen Helminthosporium solani and its close-related species H. velutinum, the primers/probe specific to the former could amplify signals from the latter. These findings highlight the need for additional methods to enhance the diagnostic accuracy and new sequencing technologies such as next generation sequencing could provide useful information to develop specific diagnostic protocols for these pathogens.

This review entails a critical appraisal on the potential of plants as alternatives to synthetic chemicals for crop protection, aligning with the global shift towards green-based approaches in agriculture. Utilising a defined set of inclusion and exclusion criteria, 235 papers were extracted from Scopus. These articles were analyzed to address specific research questions related to plant-based biocontrol methods. Approximately 25% of the literature was published in journals such as "Industrial Crops and Products", "Journal of Agricultural and Food Chemistry", "Pest Management Science", and "Frontiers in Microbiology". Thematic analysis identified core focus areas, including the chemical properties of antifungal agents, bioactive compounds, environmental protection, and the use of fungicides. Italy and China emerged as countries with the most represented authors, while China, India, and USA led in scientific production, corresponding authors' publications, and citation impact. We identified 91 plant species from 28 families, notably from the Lamiaceae, with strong potential as biocontrol agents. The most promising plants were Platycladus orientalis (L.) Franco, Mentha piperita L., Foeniculum vulgare L., Coriandrum sativum L., and Allium ascalonicium L. This study offers valuable insights and practical applications in the field of plant-based biocontrol, thereby underscoring the relevance and efficacy of green-based approaches in contemporary agricultural practices. There is an increasing scientific interest in sustainable crop protection strategies and the potential of plant-based biocontrol agents in addressing biotic stresses in crops. Overall, this review contributes to the understanding of plant-based biocontrol for crop protection, providing a foundation for further research and application in sustainable agriculture.

Dragon’s head (Lallemantia iberica) as an oilseed crop has been recently introduced to Iranian farmers and due to its tolerance to abiotic stresses grown in drylands and rain-fed areas of the country in rotation with cereals and pulses. In this study, fifty Iranian L. iberica landraces were evaluated for the prevalent diseases under field conditions during 2019–2021 in Gonbad-Kavous, North of Iran. A spot lesion/blight symptom was observed in the field and the subsequent classical and molecular mycological studies identified Alternaria tenuissima and A.atra as the causal agents. Subsequently, a complimentary experiment was conducted to screen genotypes for these disease agents under controlled conditions using the proposed scoring system invented in this study. Results showed a significant negative correlation of Sclerotinia stem rot with yield and plant height, while no relationship was observed between Alternaria spot/blight and agronomic traits. Two and twenty-one genotypes were identified as highly resistant and resistant to Sclerotinia stem rot in the field, respectively; where six of them showed additional resistance to Altarnaria spp. in the glasshouse. The resistant/high-yield genotypes identified through this research can be considered valuable sources to be released as new cultivars or exploited in breeding programs.

Leaf spot disease is commonly found on leaves of avocado plants in avocado orchards in Taiwan. Needle-like spots with yellow halos appear on diseased avocado leaves at the incipient stage, and these spots gradually enlarge and become brown lesions with black-brown centers. The causal agent of this disease is unknown. A Pseudoplagiostoma species was isolated from these leaf spots. Evaluation of morphological traits and phylogenetic analysis using the ribosomal DNA internal transcribed spacer operon, β-tubulin, and partial large subunit of ribosomal DNA markers identified this fungal species as a novel species, Pseudoplagiostoma perseae sp. nov. A pathogenicity test was conducted on three avocado cultivars, ‘Choquette’, ‘Hall’, and ‘Hung Shin Yuan’. After 2 weeks of inoculation, needle-like leaf spots appeared on all three cultivars, and P. perseae was re-isolated from the spots of all inoculated leaves, fulfilling Koch’s postulates. This is the first report describing the novel species P. perseae, which was validated as the causal agent of avocado leaf spot disease.

Both biotic and abiotic stress factors play an important role in reducing the growth and productivity of many crops. In this study, the effects of arbuscular mycorrhizal (AM) fungi and biochar (Bc) were investigated against Verticillium dahliae (Vd) disease in pepper plants grown under salt stress. These effects were evaluated on enzyme activities, salt tolerance, disease severity, plant growth and physiological characteristics. In this study, pepper was treated with 2% biochar, Funneliformis mosseae (Fm), Vd and different concentrations of salt (0 mM, 50 mM, 100 mM, 150 mM). The interaction of Fm and 2% Bc significantly increased the morphological parameters of the plant and the plant tolerated salt and Vd under combined high stress conditions of biotic (Vd) and abiotic (salt) stresses. It was also shown that Fm had a different effect than Bc on the membrane injury index (MII; %) and had a significant effect on leaf relative water content (LRWC; %). In addition, Vd increased mycorrhizal reliance, with the higher spore density of AMF higher disease severity observed in treatments involving Fm and Fm + Bc. Furthermore, phenol and antioxidant values were altered in Vd treatments, while Fm decreased CAT enzyme activation. Therefore, this study supports that AMF + biochar used in sustainable agriculture increases plant resistance to the soil pathogen (V. dahliae) and the salt stresses.

Botrytis bunch rot or gray mold caused by Botrytis cinerea, is a significant disease affecting grapevine clusters. While previous studies focused on leaf resistance, this research delves into the ultrastructural changes of grape inflorescence and fruit infected with Botrytis cinerea. Here, we investigated four grape varieties: a highly resistant Chinese wild grapevine, Vitis amurensis ‘Beibinghong’ (BH), a resistant grapevine, Vitis labrusca × Vitis vinifera ‘Shine Muscat’ (SM), a susceptible grapevine, Vitis vinifera ‘Daqing’ (DQ), and a highly susceptible Vitis vinifera ‘Red Globe’ (RG). Using light microscopy (LM), stereo microscope (SM), scanning electron microscopy (SEM), and Diaminobenzidine (DAB) staining of inoculated grape inflorescences and peels, we observed and compared the prevalence of B. cinerea infection in RG, DQ, SM, and BH, following the order: BH > SM > DQ > RG. After 72 h of inoculation, RG exhibited the highest mycelium count, accompanied by inflorescence and peel decay. In contrast, BH showed minimal mycelium on inflorescences and peels, maintaining a relatively intact epidermis. DAB staining of inflorescences revealed distinct H₂O₂ accumulation in susceptible varieties within 24 h of inoculation, whereas disease-resistant varieties showed minimal staining. Notably, highly resistant BH displayed H₂O₂ accumulation only after 72 h of inoculation. Overall, these results provide insights into the intricate interactions between the grape inflorescences, peels, and B. cinerea. Moreover, the study underscores the potential of highly resistant Chinese wild mountain grapes for developing new varieties with robust gray mold resistance.

The present investigation was designed to assess how administering biocontrol agents (BCAs) made from the nematophagous endophytic fungus MR20 (Purpureocillium lilacinum) or a mixture of endophytic plant growth-promoting bacteria MR12 (Pseudomonas fluorescens), and MR25 (Serratia marcescens), could enhance tomato growth and resistance to Meloidogyne incognita under in vivo conditions. The three strains’ cell-free culture filtrates showed a strong nematocidal impact (P < 0.05) on M. incognita infective second-stage juveniles (J2s). The highest mortality rates by the three BCAs were at concentrations of 80%, followed by 60%, 40%, and 20%. The in vitro hatching of free eggs was found to be considerably (P < 0.05) reduced as the concentrations of the endophytic bacteria MR12, and MR25 were increased in the order 1 × 10⁵, 1 × 10⁶, 1 × 10⁷, 0.5 × 10⁸, to 1 × 10⁸ colony forming units (CFU)/mL, and the maximum nematicidal activity in killing M. incognita free eggs occurred at 1 × 10⁸ CFU/mL. A statistically significant (P < 0.05) reduction in the percentage of M. incognita-free eggs retrieved was seen in vitro when various concentrations of the endophytic fungus MR20 were applied compared to the negative control (distilled water). The endophytic fungus MR20 had the highest nematicidal activity against M. incognita free eggs at a concentration of 3 × 10⁶ CFU/mL. The application of P. lilacinum or a combination of P. fluorescens and S. marcescens to tomato plants in the presence of M. incognita under greenhouse conditions resulted in a significant increase (P < 0.05) in root and shoot fresh weight, number of leaves, weight of leaves, and stem diameter when compared to the positive control treatment that contained only M. incognita. Treatment with P. lilacinum was more effective (P < 0.05) than P. fluorescens and S. marcescens in reducing egg masses per root, J2s per 100 g of soil, egg masses per 100 g of soil, J2s + eggs of M. incognita per 100 g of soil, reproduction factor, and reduction percentage after 60 days under greenhouse conditions. Nevertheless, the reduction of M. incognita gall size categorization (> 4 mm, 2–4 mm, and < 2 mm) was more effectively achieved by treatment with P. fluorescens and S. marcescens than by treatment with P. lilacinum. Under in vivo conditions, the tested P. lilacinum or a mixture of P. fluorescens and S. marcescens effectively controlled nematode population densities below the economic threshold.

Cassava (Manihot esculenta Crantz) is a major staple food in many developing countries, including Brazil. However, it faces significant challenges due to diseases such as dry root rot (DRR) and black root rot (BRR) caused by soil-borne plant pathogenic fungi. This study explored the use of cover crops to suppress these diseases and to improve the agronomic traits of cassava. Over four cultivation cycles, various cover crops (sunn hemp, black oat, jack bean, maize, peanut and cowpea) were alternated with cassava varieties 'BRS Kiriris' (resistant) and 'BRS Formosa' (susceptible) in soil infested with DRR (Fusarium oxysporum, F. equiseti, F. verticillioides, F. solani, F. lateritium, F. chlamydosporum) and BRR (Lasiodiplodia theobramae, Neoscytalidium dimidiatum) pathogens. In the 2nd cycle, only germination showed significant differences, but by the 4th cycle, various agronomic parameters, including fresh weight (FW.AP), dry weight (DW.AP) of the aerial part, fresh weight (FW.Root), dry weight (DW.Root) of the roots, and plant vigor. Cowpea was identified as the most effective cover crop for reducing the disease index (DI %) by promoting healthier and taller cassava plants. Jack beans and peanuts also had positive effects on vigor, FW.AP, DW.AP, FW.root, and DW.root. In contrast, maize, black oats, Crotalaria ochroleuca, cassava, and fallow soils had minimal impacts. Throughout these cycles, the selected cover crops consistently contributed to disease reduction and improved the agronomic performance of the cassava. This study highlights the potential of holistic disease management strategies.

Pseudomonas syringae pv. coronafaciens (Ps-c) is a pathogenic bacterium species that can be found in agricultural environments and causes diseases in plants. During a survey in 2019–2020 of different areas, bacterial halo blight (BHB) caused by Ps-c in oat (Avena sativa L.) was observed in many oat fields in Huan county, Gansu Province of China. Average leaf disease incidence was approximately 1 to 14%. The symptoms of BHB were mainly observed on leaves of oat and appeared as white to yellow streaks. After 20–30 d, the streaks became yellow necrotic lesions and spread over whole leaves, eventually causing leaves to wilt and senesce. Symptomatic leaves of affected oats were collected to investigate the etiology of BHB disease. A group of 32 bacterial isolates (HK7) phenotypically similar were isolated from the necrotic lesion margins. Pathogenicity tests of this group of isolates by wounding and injection demonstrated that the symptoms induced by them on oat were similar to those observed in the field. HK7 isolates were identified as Ps-c based on Biolog Gen III MicroStation, morphological, physiological and biochemical characterization, 16S rRNA and gyrB gene sequence analysis, which compared with a reference strain (Ps-c ATCC 19608). Furthermore, Ps-c was host specific. After inoculation of Ps-c on A. sativa (B7) and A. nuda (B2) in greenhouse by Completely Randomized Design (CRD), number of tillers, plant height, flag-leaf length, flag-leaf width, fresh weight, dry weight, panicle length, grains per spike, reproductive branche number and thousand grains weight of infected oat decreased by 19.44%, 11.49%, 11.34%, 9.23%, 11.61%, 7.57%, 6.11%, 9.73%, 9.31% and 4.15% compared with that of healthy oat, respectively. BHB (Ps-c) is a new bacterial disease on oat in China and has a negative effect on plant growth, forage and grain yield of oat, and these negative effects increased with the increase of disease severity.