Journal of Phytopathology最新文献

Diseases are one of the major factors that have the potential to reduce plant production, food security and ultimately humanity's survival. Therefore, timely and correct identification of plant diseases is important in ascertaining methods to control the diseases. This paper focuses on the application of Deep Learning in identifying plant diseases, and the research's recommendation is a combination of the Vision Transformer (ViT) and GoogLeNet architectures. The objective of this work is to combine the strengths of both models so as to attain increased accuracy and faster computation. This proves that the proposed model yields a substantial accuracy of 99.20% a, 99.30% precision and 99.10% recall. F1-score shows the highest performance compared to several state-of-the-art models. For comparison, the Vision Transformer, better known as ViT, attained a 97.80% accuracy, 97.90% precision, 97.70% recall and 97.80% F1 scores, and GoogLeNet attained 98. 60% accuracy, 98. 70% precision, 98.50% recall and 98.60% F1-score. The present hybrid model substantially enhances the capacity to identify plant diseases, hence providing a comprehensive means of managing the early diseases in the plantations. Due to high performance in the desired indicators, it is applicable for real-world purposes, controlling crops and increasing their yields.

In 2023, Adenium obesum plants displaying virus-like symptoms were observed in two locations in Brazil. High-throughput sequencing (HTS) analysis of RNA-Seq of one sample yielded a contig sequence of 3923 nucleotides (nt), showing 97.77% nt identity with the genome of pelargonium flower break virus (PFBV, genus Alphacarmovirus). Total RNA was also extracted from another sample, and the presence of PFBV was confirmed by the real-time reverse transcription-polymerase chain reaction (RT-qPCR) in these two samples. Attempts of mechanical transmission were done by inoculating sap from infected A. obesum leaves to healthy seedlings of A. obesum and Pelargonium zonale, but were not successful. However, PFBV was transmitted by grafting from and to an A. obesum plant. To the best of our knowledge, this is the first report of PFBV infecting A. obesum plants.

The development of strawberries is often impacted by inorganic and genetic terms, leading to significant risks to both quality and productivity. However, the existing approaches for disease recognition are characterised by a high rate of misinterpretation. Due to the high requirement for high strawberry productivity, relying on conventional recognition techniques primarily based on personal expertise and visual inspection is insufficient to address these challenges. Hence, it has become essential to develop more efficient approaches for accurately detecting strawberry diseases, along with providing detailed disease descriptions and suitable control measures. This work presents a clustering-based Deep Learning (DL) model for strawberry disease recognition. Initially, the input images are normalised, and the affected regions are segmented by the Fuzzy C Means (FCM) clustering. Finally, the categorisation of different diseases is classified using the DL model Adaptive Deep Residual Network (ADRN). The ADRN is the integration of the Deep Residual Network (DRN) and the Reptile Search Optimizer (RSO). The analysis is evaluated on the Strawberry Disease Detection Dataset and attained better accuracy and precision of 0.991 and 0.995, respectively.

Changes in environmental conditions, intensified by the progression of global warming, have created favourable conditions for the spread and intensification of diseases in various agricultural crops. Obtaining cultivars resistant to various abiotic and biotic stresses may be one of the solutions. In this study, the resistance of three pepper cultivars to Xanthomonas euvesicatoria pv. euvesicatoria was analysed inside a greenhouse, evaluating the severity of the disease over time. The participation of biochemical and structural mechanisms in the defence of pepper plants against this pathogen was investigated based on the determination of the activity of the antioxidant enzymes such as guaiacol peroxidase (POX), catalase (CAT), polyphenol oxidase (PPO) and lipoxygenase (LPOX). The quantification of components of the phenylpropanoid pathway (phenylalanine ammonia lyase [PAL], phenolic compounds and flavonoids), the observation of the number of stomatal cells with hypersensitivity reaction (HR) and the content of chlorophyll a, b and carotenoids were also evaluated. Plants of the cultivars All Big, Yolo Wonder and Amarelo SF were challenged with X. euvesicatoria pv. euvesicatoria and the severity evaluated at 14, 21 and 28 days after inoculation. Leaf samples were collected 24, 48 and 96 h after inoculation (HAI) for biochemical and photosynthetic analyses. The plants of the All Big cultivar exhibited 50% higher disease severity compared to the Amarelo SF and Yolo Wonder cultivars, which did not differ significantly from each other. In All Big, 48 HAI, POX activity was 37% higher than in Amarelo SF and 27% higher than in Yolo Wonder. Additionally, PPO activity was 46% higher than in Amarelo SF and 55% higher than in Yolo Wonder. After 96 h of inoculation, Yolo Wonder plants showed the highest CAT enzyme activity, 43% higher than Amarelo SF, but with no significant differences compared to All Big. Furthermore, 96 HAI, Amarelo SF stood out for its higher LPOX activity, 14% higher than All Big and 22% higher than Yolo Wonder. On the other hand, Amarelo SF also stood out by exhibiting 31% more cells undergoing a hypersensitive response compared to Yolo Wonder, but with no significant differences relative to All Big. After 96 h of inoculation, All Big plants displayed higher chlorophyll a levels, exceeding those observed in Amarelo SF by 18% and in Yolo Wonder by 17%. Despite peaks in PAL enzyme activity, as well as in the accumulation of phenolic compounds and flavonoids, no statistically significant differences were found among the evaluated cultivars for any of the measured parameters. This article explores and discusses the role of defence mechanisms, such as the antioxidant system, the phenylpropanoid pathway and the accumulation of photosynthetic pigments, in the pathosystem involving bell pepper plants and X. euvesicatoria pv. euvesicatoria.

Several phytopathogenic bacteria have been reported worldwide affecting wheat (Triticum aestivum L.), causing significant yield losses. Over the past 5–6 years, symptoms resembling bacterial mosaic, characterised by small yellow lesions with indefinite margins scattered across the leaf, have been observed in wheat plants in one of the main producing areas in Argentina, with an incidence of 10% to 20%. This emerging disease has raised concern among producers and technicians. In this study, a bacterium was isolated from symptomatic seeds, and biochemical, molecular, and genomic techniques were used to identify the causal agent. Pathogenicity tests were conducted on wheat and soybean plants through leaf infiltration, demonstrating that the strain caused disease in wheat but not in soybean. Using a combination of MALDI-TOF MS, the API 20 NE test, 16S rRNA gene, and whole-genome sequencing confirmed the pathogen as Curtobacterium flaccumfaciens. Phylogenomic and genome-to-genome comparisons showed the strain sequenced grouped within the type strain sequence of C. poinsettiae CFB 2403. To our knowledge, this is the first report of Curtobacterium flaccumfaciens as a pathogen on wheat in Argentina. This research contributes significantly to understanding this phytosanitary problem with detailed information on the pathogen, using advanced technology and new reclassifications of pathogenic bacteria, which will allow the development and implementation of effective management strategies in the future.

Lipopolysaccharides (LPS) are structural components of gram-negative bacteria that potentially induce innate immune responses in plants. A previous study demonstrated that an LPS acts as an elicitor, triggering systemic resistance against bacterial spot in tomato caused by Xanthomonas euvesicatoria pv. perforans. However, its long-term impact on plant growth, disease control and productivity remained unclear. The first experiment determined the optimal concentration of the crude LPS for effective bacterial spot control without deleterious effects on plants. The second experiment evaluated LPS application methods and timings that provide balanced benefits for plant growth, productivity and control of bacterial spot and powdery mildew. Additionally, the involvement of polyphenoloxidase and phenylalanine ammonia-lyase (PAL) in disease resistance was also investigated through gene expression assays. Results estimated 7.3 μg/mL as the optimal dose for minimising disease severity without compromising chlorophyll content. At least one application in the vegetative stage, using either electrostatic spraying or soil dispensing, yielded the most balanced outcomes for plant growth, productivity and disease control. Electrostatic spraying provided an average reduction in severity of 60% for bacterial spot and 32% for powdery mildew, while soil dispensing provided 58% and 28%, respectively. These treatments also promoted increased PAL gene expression, suggesting that this enzyme is involved in the resistance response.

Fusarium graminearum is the dominant pathogenic fungus of the Fusarium head blight (FHB) which seriously damages the yield and quality of wheat in China. The gene FgNiR encodes nitrite reductase (NiR) of the nitrogen reduction pathway in F. graminearum. However, the function and role of the FgNiR were unclear. In this study, FgNiR gene deletion mutants were compared with wild-type strains and complementary mutants in terms of functional roles, including vegetative growth, tolerance to abiotic stress, sensitivity to fungicides, utilisation capacity of nitrogen sources, pathogenicity and the expression levels of Tris genes and nitrate reductase gene (FgNR). The results showed that FgNiR deletion significantly reduced the conidial germination rate and speed and pathogenicity of wheat coleoptile. The mycelial growth inhibition rates of deletion mutants were significantly decreased under osmotic stress but increased under oxidative stress. The inhibition rates of the deletion mutants treated with Congo red significantly increased. The EC₅₀ values of triazole fungicides and fluazinam of the deletion mutants were significantly higher, but the EC₅₀ values of phenamacril were significantly decreased. When FgNiR was absent, there were different degrees of difference in utilisation capacity of nitrogen in F. graminearum, and the expression level of FgNR was upregulated. The expression of Tris gene showed that the expression levels of Tri1, Tri5 and Tri10 were significantly upregulated. These results are of crucial scientific significance for exploring the specific interaction mechanism of FgNR and FgNiR and developing efficient strategies for the prevention and control of FHB.

Cucurbita maxima is an important Cucurbitaceous vegetable crop cultivated for its immature and tender fruits used in various culinary applications. During the survey in 2022, we found that the C. maxima crop was severely affected by the genus begomovirus-like disease, which is associated with mosaic and leaf curl, with 40%–75% disease incidence. The symptomatic leaves were collected for the biological and molecular identification of begomovirus in C. maxima. The associated disease was successfully transmitted by whiteflies in a transmission study from naturally infected C. maxima to healthy C. maxima and other test host plant species in 30 days post inoculation. The complete viral DNA-A genome was successfully amplified by begomovirus gene-specific primers through PCR, and nucleotide sequence data were submitted to the NCBI GenBank database (Acc. No. OQ320769). The isolates (OQ320769) showed 97%–98% nucleotide sequence identities and close phylogenetic relationships with various isolates of Tomato leaf curl Palampur virus (ToLCPalV). Therefore, the isolates under study were identified as ToLCPalV. To the best of our knowledge, C. maxima is a new host of ToLCPalV associated with mosaic disease, and it has been identified for the first time in India, which could pose a major constraint to C. maxima production in Central India.

Phytophthora capsici can induce severe economic losses in the tomato (Solanum lycopersicum) crop. However, broad-spectrum and phenotypically stable sources of resistance to this highly variable pathogen are not yet identified in Solanum (section Lycopersion) germplasm. We evaluated, in three bioassays, the reaction of Solanum (Lycopersicon) accessions against seven P. capsici isolates. All isolates across all bioassays induced severe symptoms in the susceptible control Capsicum annuum ‘Tico’. The Ralstonia solanacearum-resistant tomato ‘Hawaii-7996’ displayed superior levels of resistance to four isolates, whereas S. habrochaites ‘WIR-7924’ displayed resistance to five isolates. The resistant/susceptible reactions of the accessions were not coincident, indicating the presence of isolate-specific resistance factors as well as potential pathogen pathotypes. Large-spectrum genetic resistance to P. capsici isolates is essential for sustainable management of this pathogen. Hence, combining resistance factors from ‘Hawaii-7996’ and S. habrochaites ‘WIR-7924’ into a single cultivar would be a promising breeding strategy aiming to develop tomatoes with resistance to a wide array of P. capsici isolates.