Journal of Phytopathology最新文献

Tomato leaf curl New Delhi virus (ToLCNDV), a begomovirus, that causes severe leaf curling, stunting, and reduced yield in tomato plants is consistently threatening its production worldwide. CRISPR/Cas9-mediated genome editing has shown immense potential in developing disease-resistant crops. This study successfully focuses on designing a precise and efficient strategy for in planta defence against ToLCNDV. Five key targets within the viral genome, essential for its replication and pathogenicity, were selected. Five Cas9-expressing constructs, along with the ToLCNDV infectious clone, were agroinfiltrated into tomato plants. Three constructs effectively disrupted the ToLCNDV genome. These three constructs, 1T, 2T, and 4T, were shortlisted based on symptom severity level. They showed a relatively low viral titre of 0.5, 0.42, and 0.25 through quantitative real time PCR (qPCR) after 3, 6, and 9 days of post-co-infiltration, respectively. Positive control plants showed significant signs of infection like yellowing of leaves, thickening of veins, and majorly upward curling of leaves. In comparison, plants infiltrated with three Cas9 constructs had mild yellowing of leaves that recovered after approximately 21-dpi. Furthermore, we assessed the agronomic performance of Cas9-mediated tomato plants through in planta Agrobacterium-mediated transformation with three short-listed guided RNA (gRNA) constructs under greenhouse conditions. Also, qPCR analysis of Cas9 protein in 7, 14, and 21-day of intervals gave a relative expression of 0.85, 0.76 and 0.51 respectively in genetically engineered (GE) plants through in planta transformation. In conclusion, this research contributes to CRISPR-Cas9-mediated plant genome editing. Our findings substantiate the efficacy of the CRISPR/Cas9 system in achieving durable engineering of resistance against ToLCNDV with 30% transformation efficiency in tomato plant. Furthermore, this study illuminates potential avenues for extending the application of this technology to confer resistance against singular and multiple infectious viruses in diverse crop species.

Biological control has emerged as a leading approach in managing crop diseases including Fusarium wilt of cashew caused by Fusarium oxysporum f.sp. anacardi. However, this approach is limited by the high cost of commercially available growth media and ultimately lacks applications at the farmer's level. The study examined three organic-based substrate formulations (rice bran, rice husk and their combination) of four combined Bacillus strains (Bacillus subtilis 4/5021 and Bacillus velenzesis 10/5140, 11/A + 1 and 13/A + 3) or Trichoderma asperellum to control the disease. The experiments were conducted in farmers' fields in 2021/2022 and 2022/2023. The treatments were applied once during the rainy season by soil drenching at a rate of 20 mL of bioformulation per litre of water around each tree. The results revealed that the treated cashew trees had significantly (p ≤ 0.05) lower final disease severity (between 15.17% and 33.75% in 2021/2022 and 14.43%–31.93% in 2022/2023) than the untreated trees (77.17% and 89.31%, respectively). The only treatment that was not significantly different from the control was the rice husk–T. asperellum formulation in both years. In treated plots, disease severity decreased over time each year, whereas disease severity increased in untreated trees. Based on these results, the three formulations of Bacillus strains and two of the Trichoderma asperellum formulations (bran-based or bran–husk combination) should be evaluated further for the management of Fusarium wilt of cashew. This study offers a potential solution to utilise locally available organic substrates for developing liquid-based formulations of biological control agents.

Tef head smudge (Curvularia miyakei) is an economically important plant disease in the warm-humid regions of the Western Amhara Region, Ethiopia. Therefore, this study aimed to assess the geographical distribution, habitat suitability and epidemiological factors influencing the incidence and severity of Tef head smudge disease. The result of the study depicted that Tef head smudge disease is widely distributed across the region at varying levels of incidence and severity. Sowing date, soil type, altitude and growth stage are the key epidemiological factors contributing to the variability in the incidence and severity of Tef head smudge disease. Moreover, isothermally, temperature seasonality and minimum temperature of the coldest month bioclimatic variables significantly influenced Tef head smudge disease dynamics. Our study also predicted the current habitat suitability of Tef head smudge disease using the MaxEnt (maximum entropy) species distribution model. The model was good in predicting Tef head smudge disease with an AUC (area under the Receiver Operating Curve) of 0.85. According to the model, 31.18%, 44.46% and 14.33% of the areas have highly suitable, moderately suitable and low suitable suitability respectively, whereas 10.03% of the areas have unsuitable suitability to Tef head smudge disease. This result underscores that a significant portion of the Western Amhara Region (75.64%) and similar agro-ecologies are at risk of Tef head smudge disease outbreaks. Therefore, it is important to implement targeted breeding programs and disease management strategies to ensure food security in regions where tef is a primary food source and Tef head smudge is prevalent.

Coffee leaf rust (CLR), caused by the fungus Hemileia vastatrix, is a very devastating disease affecting coffee production in many countries worldwide and causing yield losses that range from 15% to 50%. High CLR intensity on coffee trees impairs photosynthesis and causes intense defoliation resulting in fewer and smaller fruit berries on trees. New control methods for CLR that will reduce the use of fungicides and production costs need to be investigated and used in an integrated disease management program. In this study, it was hypothesised that azelaic acid (AzA), a C9 dicarboxylic acid (oxylipin) known to be involved in systemic acquired resistance, could boost defence reactions on the leaves of coffee (Coffea arabica, cultivar Catuaí Vermelho—IAC44) against infection by H. vastatrix. In the in vitro assay, urediniospores germination was significantly reduced (81%–86%) by AzA with concentrations from 1 to 20 mM. Fungal sporulation was much more intense on the leaves from water-sprayed plants compared to leaves from AzA-sprayed plants at both 22 and 30 days after inoculation (dai). The area under CLR progress curve and the intensity of fungal sporulation were significantly lower by 82% and 83%, respectively, and the incubation period was higher by 31% for AzA-sprayed plants compared to water-sprayed ones. The AzA-sprayed plants infected by H. vastatrix displayed less photosynthetic impairments considering the greater values for rate of net CO₂ assimilation, internal CO₂ concentration, transpiration rate, and maximum photochemical efficiency of photosystem II compared to water-sprayed and infected ones. On top of that, these plants displayed higher concentrations of chlorophyll a + b and carotenoids and a more robust antioxidative metabolism (increased ascorbate peroxidase, catalase, and glutathione reductase activities at 12 dai). Interestingly, activities of chitinase, β-1,3-glucanase, phenylalanine ammonia-lyase, peroxidase, and polyphenoloxidase were lower for AzA-sprayed plants as a result of reduced colonisation and sporulation of H. vastatrix in contrast to water-sprayed and infected ones. Higher concentration of superoxide anion radical for AzA-sprayed plants and infected by H. vastatrix at 12, 22, and 30 dai may have helped to reduce the colonisation of coffee leaf tissues by H. vastatrix besides having a citotoxic fungistatic effect against the fungus. These results strongly support the potential of AzA to negatively affect the germination of urediniospores from H. vastatrix as well as to hamper the infection process of H. vastatrix on coffee leaves.

Mungbean is an economically important short-duration traditional pulse crop in Pakistan. During a routine inspection of mungbean fields in the summer of 2018, unusual disease symptoms reminiscent of Tospovirus were observed for the first time. These symptoms include severe leaf chlorosis, necrosis, plant stunting and death. To identify the causal virus, symptomatic fresh leaves were analysed following RT-PCR using GBNV-specific primer pair which resulted in the amplification of ~0.8 kbp fragment specific to CP gene of Groundnut bud necrosis virus (GBNV). A representative amplicon was cloned and sequenced. The analysis of the attained sequence confirmed its high resemblance with GBNV earlier reported from different crops in India. The virus was successfully mechanically inoculated onto the mungbean genotype MH-21006 which produced similar symptoms as observed under field conditions. Under the present study, based on the visual assessment, 132 mungbean advanced genotypes and approved varieties were also evaluated against GBNV under field conditions. Data showed that 122 genotypes were resistant with percent disease index (PDI) value ranging from 1.3% to 9.9% while 10 were tolerant with PDI value ranging from 10.3% to 14.2%. Present findings confirm the first natural association of GBNV with mungbean in Pakistan.

Sweet potato foot rot, caused by Diaporthe destruens, has been recently reported in various regions in Japan. To investigate genetic diversity of D. destruens within Japan, 135 isolates of D. destruens were collected in 12 prefectures in Japan, and ITS, TUB, TEF, H3 and CAL regions were sequenced. In all regions, there was no difference of sequence among all collected isolates, implying high genetic homogeneity of the fungus spread in Japan. A phylogenetic tree was constructed for ITS sequence with other strains registered in NCBI database. In the tree, our samples were positioned closely to samples in Korea and China but distant from most of the samples in Taiwan. Our study implies genetic relationships between D. destruens strains in Japan and other countries.

Multi-nutrient deficiency in crops, involving a shortage of essential nutrients such as nitrogen, phosphorus and potassium, impacts plant growing and yield. Accurate recognition is vital for effective nutrient management and maximising productivity. Identification techniques include extractive methods that analyse symptoms and abstractive methods that generate insights from data, with hybrid approaches aiming to improve the accuracy. However, challenges remain in maintaining diagnostic consistency and so forth. Continuous improvements are necessary to better integrate and interpret complex data for more accurate nutrient deficiency identification. To tackle these challenges, this research proposes the customised convolutional neural network-transfer learning (CCNN-TL) model for identifying multi-nutrient deficiencies in paddy leaves. This model includes several key phases: image preprocessing, segmentation, feature extraction, data augmentation and identification. Initially, the paddy leaf images undergo preprocessing using the improved Wiener filtering (IWF) technique. Next, the modified U-Net model is proposed for segmenting the preprocessed images. In the feature extraction phase, relevant features are identified from the segmented images. These features are then augmented through the data augmentation process. Finally, the CCNN-TL model is used for multi-nutrient deficiency identification. The model's effectiveness is demonstrated through comprehensive simulations and experimental evaluations. These evaluations showcase its enhanced performance, with improved accuracy, precision and specificity compared to traditional methods. The CCNN-TL scheme attained the greatest accuracy of 0.982, precision of 0.975 and F-measure of 0.973. The Nutrient-Deficiency-Symptoms-in-Rice dataset was employed for simulations and analysis, ensuring a solid foundation for the evaluations.

In the spring 2018, a leaf disease including light and necrotic spots with irregular edges surrounded by chlorotic halos was detected on common mallow in Jiroft County (Kerman Province, Iran). A bacterium-forming cream-coloured and mucoid colonies on King's B agar medium was consistently isolated and was fitting of the traits of the genus Pseudomonas. Isolated strains caused spots on common mallow leaves in the pathogenicity test that was identical to natural field symptoms and belonged to Pseudomonas viridiflava based on phenotypic characteristics including LOPAT tests. Two representative isolates were further confirmed as P. viridiflava with 99% sequence identity after sequencing the 16S rRNA and gyrB genes. To our knowledge, this is the first report of P. viridiflava causing leaf spot disease on common mallow in Iran.

Hosta (Hosta plantaginea L.) is a perennial herbaceous plant belonging to the family Liliaceae. It is widely cultivated for its decorative foliage and dainty, colourful flowers. Fusarium is a globally prevalent plant pathogen. During 2020–2021, 116 Fusarium isolates were isolated from 300 hosta leaf blight samples collected from eight cities in China, and 65 representative isolates we selected for further study. The 65 isolates were identified based on the concatenated sequences of the tef1 and rpb2 genes, which grouped them into 12 Fusarium species, including F. acuminatum (27.59%), F. verticillioides (15.52%), F. oxysporum (10.34%), F. armeniacum (10.34%), F. ipomoeae (8.62%), F. proliferatum (6.9%), F. subglutinans (6.9%), F. humuli (3.45%), F. petersiae (3.45%), F. brachygibbosum (3.45%), F. graminearum (1.72%), and F. compactum (1.72%). Pathogenicity tests demonstrated that all Fusarium isolates exhibited high pathogenicity towards hosta leaves. Whereas in F. proliferatum isolates were found to be the most pathogenic. All Fusarium species obtained in this study are first reported as the causal agents of hosta leaf blight in China except F. oxysporum and F. ipomoeae. The current research offers insights into disease management, phylogenetic relationships amongst Fusarium species and the diversity of Fusarium species associated with hosta leaf blight.