Journal of Phytopathology最新文献

Potato (Solanum tuberosum L.) is of great economic importance for Mauritius. During a disease survey carried out in a field in one of the major potato-growing regions of Mauritius, corky cracked lesions with halo and mycelial growth were observed on the skin surfaces of around 45% of tubers. The suspected fungus from the affected areas was isolated on amended potato dextrose agar and after 7 days, several fast-growing, pale brown Rhizoctonia-like colonies with a few sclerotia were observed. Additionally, microscopic analysis revealed some cells being multinucleate, forming hyphal branching at right angles with slight constriction together with septum near the branch base. Pathogenicity tests confirmed development of the same symptoms on potato tubers and the causal agent was reisolated successfully. Sequence analysis of the ITS region of representative isolate P114 amplified using ITS1F/ITS4 primers showed that it was identical to several isolates of multinucleate Rhizoctonia solani AG-4 HGI, and neighbour-joining phylogenetic analyses confirmed the identification. To our knowledge, this is the first report of R. solani AG-4 HGI-infecting potato tubers and causing corky cracks in Mauritius.

Cowpea (Vigna unguiculata), known for its high nutritional value, is one of the most important edible beans worldwide. In September 2023, a root rot disease was found in a greenhouse in Nanchang, Jiangxi Province, with symptoms of plant wilting. The isolates from the diseased samples were identified as Fusarium concentricum, F. fujikuroi and F. incarnatum based on morphological characteristics and phylogenetic analysis of four loci including the internal transcribed spacer region (rDNA-ITS), translation elongation factor 1-alpha (TEF1), beta-tubulin (TUB2) and calmodulin (CAM). The pathogenicity of the representative isolates was confirmed on asymptomatic cowpea seedlings. Although other Fusarium species, particularly F. oxysporum, have been previously reported as pathogens of cowpea, this study is the first to document F. concentricum, F. fujikuroi, and F. incarnatum as causative agents of cowpea root rot in China.

In 2022, potato plants exhibiting symptoms of stem canker were observed in commercial fields in northern Sinaloa, Mexico. Morphological characterisation of two isolates allowed the identification of Ceratobasidium sp., whereas molecular analysis using sequences of the ITS region and the rpb2 gene distinguished the isolates within the Anastomosis Group A (AG-A). Both isolates induced symptoms of stem canker on inoculated potato plants and exhibited median EC₅₀ values of 19.46, 5.20, 62.71 and 0.33 μg mL⁻¹ for the fungicides thiophanate methyl, pyraclostrobin, prochloraz and penflufen, respectively. However, the two isolates differed by > 65-fold in their EC₅₀ value relative to pyraclostrobin.

Fusarium basal rot (FBR), caused by Fusarium spp., is a significant threat to garlic production globally, including in Türkiye, where the unique Taşköprü garlic is highly valued. This study investigated the diversity and aggressiveness of 77 Fusarium isolates obtained from disease surveys of FBR in Taşköprü garlic and evaluated the yield and resistance of 20 garlic accessions, including 18 local landraces, the locally developed ‘Taşköprü 56’, and the commercial Chinese variety ‘ASCG’. Molecular identification using translation elongation factor 1-α (TEF1) and second largest RNA polymerase II B-subunit (RPB2) genes revealed F. oxysporum (67.5%) as the dominant species, followed by F. proliferatum (15.6%), F. solani (9.1%), F. redolens (5.2%) and F. clavum (2.6%), respectively. All isolates were pathogenic, but aggressiveness varied, with F. solani being the most aggressive, followed by F. redolens and F. oxysporum. While ‘ASCG’ exhibited the highest yield (3.15 ton/ha), it was highly susceptible to FBR (DSI = 97.50%). Conversely, the landrace ASTK2 displayed the highest resistance (DSI = 53.13%), but lower yield. Promisingly, several Taşköprü landraces, such as ASTK6 and ASTK13, demonstrated both moderate resistance and promising yield potential. Surprisingly, ‘Taşköprü 56’, despite being a locally developed variety, exhibited high susceptibility to FBR (DSI = 93.75%) and did not outperform many landraces in terms of yield. This study provides the first reports of F. redolens and F. clavum infecting garlic in Türkiye, and the first molecular characterisation of F. solani as a garlic pathogen in the country, highlighting the potential of local landraces for breeding FBR-resistant, high-yielding cultivars.

Kiwifruit (Actinidia deliciosa) production in northeastern Türkiye is facing an emerging threat from Armillaria root rot. Surveys conducted in August 2021 and 2022 revealed that 10.5%–17.5% of the 200–500 vines within each of 35 kiwifruit orchards in the Perşembe, Gülyalı and Altınordu districts of Ordu province exhibited symptoms of Armillaria root rot, including complete defoliation. Diseased plants exhibited diagnostic signs on their root collars and woody roots, including white mycelial fans, extensive wood rot and rhizomorphs. A single Armillaria isolate was obtained from each of the 35 symptomatic orchards. Molecular identification, employing DNA sequencing of the large subunit (LSU) region of rDNA, the translation elongation factor subunit 1-alpha (TEF1) gene and the second largest RNA polymerase II B-subunit (RPB2) gene, identified 20 isolates as Armillaria gallica and 15 as A. mellea. Phylogenetic analyses, based on TEF1 alignments, further supported the species identification with a 100% bootstrap value. To examine genetic diversity, start codon targeted (SCoT) marker 13 was used, successfully differentiating the two Armillaria species and revealing three distinct clades. Clades I and II comprised 15 and 5 isolates of A. gallica, respectively, while Clade III contained all 15 A. mellea isolates. Pathogenicity testing on kiwifruit seedlings (cv. Hayward) revealed the ability of both A. gallica and A. mellea isolates to induce disease. Rhizomorph-producing isolates in kiwifruit seedlings displayed high virulence, inducing severe leaf necrosis and seedling mortality, while isolates lacking these structures were non-pathogenic. This study identifies the first global instance of A. gallica causing kiwifruit root rot. This finding, along with the identification of A. mellea as a causal agent in the country, highlights the emerging threat of Armillaria root rot to kiwifruit production in the region.

The current study was carried out to assess the alkaloid-enriched constituents of Prosopis juliflora (Fabaceae) against bacterial blight of pomegranate. Utilising plant extracts for disease management offers an eco-friendly approach. In vitro assessment of the minimum inhibitory concentration (MIC) for alkaloid-enriched fractions from the leaves and inflorescence of P. juliflora revealed a 14 mm zone of inhibition, with the lowest MIC value being 30 mg/mL. Untargeted metabolomics analysis of alkaloid-rich fractions (ARF) from four different tissues of P. juliflora, subjected to LC–MS for alkaloid identification, detected a total of 1489 peaks in positive mode and 240 peaks in negative mode. The highest peaks were detected in the leaves, where 47 metabolites and 9 alkaloids were identified. Ellipticine and ormosanine were found in relatively high concentrations across all four tissues, as indicated by their peak areas. The inflorescence had significantly high concentrations of sparteine, solanidine-I and puberanidine compared with other parts. Additionally, acetylsolanine was more abundant in the inflorescence, while solasodine-I was more prevalent in the leaves. A substantial amount of strictosidine was also found in the inflorescence.

Alligator weed (Alternanthera philoxeroides), originally from South America, is a notorious semi-aquatic invasive species in many countries, including India. Due to its amphibious nature, it not only damages the aquatic environment but is also detrimental to the terrestrial ecosystem. To seek an environmentally sound control option for alligator weed, this study focused on selecting an appropriate mycoherbicidal agent. A series of steps from field survey-based collection, isolation and selection of promising fungal strains, followed by host range determination to biocontrol potential studies against the weed were undertaken. Twenty-three phytopathogenic fungi were isolated, and among these, the fungi with the highest herbicidal activity (> 90% disease severity) were subjected to morphological and molecular characterisation and identified as Alternaria alternantherae (= Nimbya alternanthera). The fungus and its crude metabolites were tested against 76 plant species, showing a relatively narrow host range. This fungal species is being reported from West Bengal, India, for the first time. Although the fungus has been considered as a potential biocontrol tool against alligator weed in countries such as Australia, Brazil and China, long-term, detailed research for A. alternantherae and its active metabolites to be developed as bioherbicides against alligator weed remains indispensable.

Modern technology is revolutionising traditional farming processes by introducing new and streamlined approaches. Despite these advancements, challenges such as disease identification, insect detection and weather forecasting persist. To address these issues, this work proposes a DHMPD-based IoT-UAV smart agriculture system focused on pest detection. The method involves several stages: data acquisition, preprocessing, data augmentation, segmentation, feature extraction and classification. During data acquisition, a ‘Pest data set’ is collected. Preprocessing includes Z-score normalisation to produce better-normalised images. Data augmentation involves rotating images to create different orientations. The segmentation stage uses an updated HDBSCAN process, which improves the distance calculation between pixels using hybridised Euclidean and Minkowski distances. Feature extraction retrieves various features from segmented images, including modified MBP features, colour-based features and shape-based features. After feature extraction, the classification phase is performed by a hybrid technique with DL approaches such as improved DBN and LSTM approaches. Finally, classification results are averaged to predict pest detection accurately. The approach's effectiveness is evaluated through various assessments, aiming to overcome current limitations and enhance smart agriculture systems. The proposed DHMPD method was compared with state-of-the-art approaches and traditional classifiers, achieving a maximum accuracy of 0.936, outperforming conventional methods in accurately detecting pests. Hence, the proposed work holds immense promise to advance the capabilities of smart agriculture systems, offering practical solutions that can benefit farmers, agricultural researchers and industries involved in crop management and food production.

Wheat stem rust (caused by Puccinia graminis f.sp. tritici) is a damaging disease widespread in all grain-producing regions of the world. In this work, the effectiveness of Sr genes was analysed under field conditions in the southern region of Russia (Krasnodar Krai, Stavropol Krai and Rostov Oblast) during 2016-2021. The data were obtained using a set of 46 isogenic lines and varieties with artificial inoculation. The Sr31 gene proved absolute effectiveness in the field. Effective (1R–10R) Sr genes were the following: 5, 12, 35 and 37; moderately effective (10MR–30MR) Sr genes: 1, 6, 9g, 10, 11, 13, 14, 15, 20, 22, 23, 24, 25, 32, 33, 38 and WLD. Lines with Sr genes 7a, 7b, 8a, 8b, 9a, 9b, 9d, 9e, 9f, 16, 17, 19, 21, 26, 27, 29, 30, 36, 39, 40, 44, Dp2, Gt and Tmp were ineffective in the adult plant phase (30MS–70S). Polymorphism of infection types and disease severity was noted for most of these lines in different years. Ongoing analysis of the efficiency of Sr genes in the region is important to prevent the risk of epidemics, and lines with stem rust resistance genes that have shown efficiency can be used as donors in breeding programmes.