European Journal of Plant Pathology最新文献

The genus Pythium comprises approximately 120 species of oomycetes that inhabit diverse niches, ranging from terrestrial ecosystems to saltwater estuaries. While many species are strict soil saprophytes, others, such as P. ultimum, act as plant pathogens, causing diseases in a wide range of economically important crops. Current control measures for P. ultimum primarily rely on chemical applications to seeds and crops, as well as the use of resistant cultivars. However, the increasing emphasis on environmental conservation has led to the exploration of more sustainable agricultural alternatives, including biological control practices. In this study, we screened soil bacteria from cotton fields to identify isolates with controlling activity against this oomycete. Out of 100 bacterial isolates recovered, no effective antagonistic activity was observed among strains belonging to the genera Bacillus or Pseudomonas. The majority of controlling isolates were identified as various strains of actinobacteria, exhibiting distinct macroscopic characteristics and strong inhibition of P. ultimum growth. These actinobacterial strains caused significant macroscopic alterations in the oomycete mycelium, resulting in reduced density of its aerial structures. These promising findings highlight the potential of actinobacterial strains as biocontrol agents against one of the most problematic soil-borne plant pathogens, offering a viable alternative to chemical interventions in agriculture.

This paper is dedicated to the memory of the APS Fellow Prof. Yehoshua Anikster (1934 -2023). A total of 336 urediniospore isolates of Puccinia graminis f. sp. tritici (Pgt) were derived from samples collected in Israel from 2009 to 2019 and analyzed for virulence with the standard set of 20 differentials. Seventy-four virulence phenotypes were identified during the survey. Two Pgt phenotypes (TKTTF, TTTTF) were found in nine annual populations while 57 appeared in only one year, in most of the cases (51) only once. The yearly pathogen collections of 2009 – 2014 differed from the collections of 2015-2018, and the 2019 collection diverged from all others. No virulence to Sr24 and Sr31 indicators of UG99 was detected. When comparing the 2009 – 2014 and 2015 – 2018 periods, virulence frequencies declined for Sr17, 30, and 38 genes from 0.85—0.98 to 0.31 – 0.59, while the frequency for Sr36 rose (0.42 vs. 0.87). The average relative virulence complexity of Pgt phenotypes decreased from 0.83 (2009—2014) and 0.79 (2015 – 2018) to 0.67 in 2019. Variability within the annual populations gradually increased over time. The Pgt collections of isolates in 2009 – 2014 and 2015 – 2018 were significantly different (p = 0.01). The effective number of different annual populations in 2009 – 2018 was 2.04 (β-variation = 0.12). Since Pgt does not over-summer in Israel, the northern source of inoculum from Turkey and Russia seems the most probable.

The current study investigated how well an aqueous extract of Rubia cordifolia and a Bacillus amyloliquefaciens bacterium strain (DW6 OR083409) protected Vigna unguiculata L. plants from Fusarium oxysporum infection. In vitro study revealed that Rubia cordifolia aqueous extracts at 10% and 30% did not exhibit antifungal activity against F. oxysporum isolate, likewise no inhibition towards F. oxysporum as a presence of B. amyloliquefaciens DW6. Molecular identification characteristics confirmed the fungal pathogen being F. oxysporum AWEKA, based on the 18s rRNA sequence. B. amyloliquefaciens was found to produce indole-3-acetic acid, gibberellic acid, and hydrogen cyanide at concentrations being 203.67 ± 5.6, 335.6 ± 7.5, and 218 ± 6.4 µg/ml, respectively. In vivo, the growth of plants enhanced the induced resistance of cowpea plants against F. oxysporum during treatments with the biotic agents. The activity of defense-related enzymes was also enhanced, where Bacillus culture showed the highest increase, followed by the R. cordifolia at 30% extract and bacterial supernatant, respectively. SEM investigation of infected cowpea roots revealed notable differences in xylem vessels, including tylose formation and obstruction of vessels. Plasmolysis of parenchymal cells and hydrolysis of some cells were observed following the fungicide treatment. Both Bacillus amyloliquefaciens DW6 and the 30% aqueous extract of R. cordifolia proved effective in enhancing the induced resistance of cowpea against F. oxysporum, leading to a reduction in the damage caused by Fusarium root infection. Interestingly, this is the first report attaining the boosting of Vigna unguculata’s immune system towards F. oxysporum using aqueous extract of R. cordifolia and endophyte bacterium; B. amyloliquefaciens.

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Anthracnose caused by Colletotrichum gloeosporioides is a major postharvest disease of mango. Melatonin (MT) is an endogenous plant hormone that plays a crucial role in both biotic and abiotic stress responses. The objective of this study was to explore the impact of MT treatment on anthracnose disease of “Tainong” mango fruit through both in vivo and in vitro experiments. In vivo tests showed that 0.2 mmol L⁻¹ MT clearly postponed the occurrence of anthracnose and effectively reduced the lesion diameter on inoculated mango fruit. However, in vitro tests showed that MT had no significant effects on mycelium growth and spore germination of C. gloeosporioides. Further in vivo analysis demonstrated that MT significantly increased the activities of enzymes involved in phenylpropanoid metabolism and pathogenesis related proteins, as well as the contents of flavonoids, anthocyanins, lignin and total phenols in mango fruit. MT treatment caused an obvious production in the initial hydrogen peroxide (H₂O₂) and nitric oxide (NO) contents in inoculated mango fruit, while it decreased their content at later stages by enhancing the activities of antioxidant enzymes. Furthermore, MT significantly reduced the activity of cell-wall hydrolases and the soluble pectin content, and slowed down the loss of cellulose and protopectin. Principal constituent analysis (PCA) and correlation analysis showed that MT enhanced the resistance of mango fruit to C. gloeosporioides by enhancing defense enzyme activities and the contents of secondary metabolites and inhibiting pectin hydrolysis. In summary, MT can be an effective alternative to fungicides aimed at controlling postharvest anthracnose.

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.