Journal of Phytopathology最新文献

Divergent biotic stresses adulterate tomato fruit and degrade its quality in maturation, harvesting, and in preservation phases. Mycotic infections are attributable to a substantial decline in the quantity and quality of fruits. This study focused on the prognosis and control of post-harvest fruit rot of tomato. Infected fruits were collected, and the etiological agent was recognised as Aspergillus fumigatus by employing microscopic, morphological and molecular analyses. To prevent fruit rot disease of tomato, Fe₂O₃ nanoparticle (NPs) were synthesised by utilising fruit extract of Terminalia chebula . UV–vis spectroscopy depicted the absorption peak at 268 nm corroborating the nanoscale formation of Fe₂O₃ NPs. Fourier transform infrared indicated the presence of organic compounds (amines, phenol, ester, sulfoxide, aldehyde, alkane and alcohol) on nanoparticles. X-ray diffraction analysis delineated the average size of 29.35 nm and crystalline nature of Fe₂O₃ nanoparticles. Scanning electron microscopy provided insight into the cube-shaped morphology of nanoparticles, and energy dispersive X-ray demonstrated the existence of Fe and O peaks. These Fe₂O₃ NPs manifested a substantial suppression of mycelial growth both in vivo and in vitro. Among all concentrations, 1.0 mg/mL concentration of Fe₂O₃ NPs exhibited the highest efficacy, suppressing mycelial growth by 88.54% in vitro. At the same concentration, Fe₂O₃ NPs markedly suppressed the progression of tomato fruit rot (76%), in vivo. At 1.0 mg/mL concentration of Fe₂O₃ NPs, tomato fruit demonstrated a high amount of titratable acidity, reducing sugars, total sugars, total soluble solids, ascorbic acid, lycopene, and maintained fruit firmness. Our findings indicate that Fe₂O₃ NPs synthesised from fruit extract of T. chebula are effective in controlling fruit rot, prolonging shelf life, and maintaining the fruit quality. These nanoparticles are environmentally sound and efficacious substitutes for chemical fungicide.

The biochemical responses of two mung bean (Vigna radiata L.) cultivars to charcoal rot disease, caused by the fungal pathogen Macrophomina phaseolina, were investigated under controlled greenhouse conditions. The cultivars were Bireshwar (WBM 4-34-1-1), which is resistant to the disease, and Samrat (PDM-139), which is susceptible. The greenhouse environment was maintained at a temperature of 24°C ± 2°C and a relative humidity of 85%–90%. These cultivars were initially identified for their varying resistance levels through field screening. Seeds were treated with four distinct defence-inducing compounds: salicylic acid (SA), chitosan, yeast extract and jasmonic acid (JA). These elicitors were applied at three concentrations: SA (0.5, 1, 2 mM), chitosan (0.01, 0.03, 0.07 mM), yeast extract (0.02%, 0.05%, 0.1%) and JA (0.02%, 0.05%, 0.1%). The treated plants exhibited a notable and statistically significant enhancement in the accumulation of several defence-related biochemical markers, including catalase (CAT), peroxidase (POD), polyphenol oxidase (PPO), phenylalanine ammonia lyase (PAL), ortho-dihydroxy phenols (OD phenols), total phenols and ascorbic acid, when compared to the untreated control group. SA at higher concentrations was most effective, followed by chitosan and JA, in enhancing these biochemical defences. Following pathogen inoculation, elevated levels of CAT, PAL, POD, PPO, OD phenols and total phenols were associated with reduced disease severity. Correlation analysis revealed a strong negative relationship between Percent Disease Index (PDI) and most biochemical variables, especially at 20 days after sowing (DAS), except for PPO and ascorbic acid. These findings underscore the critical role of biochemical defence mechanisms in conferring resistance to charcoal rot disease. The study suggests that high levels of biochemical activity during the early stages of plant development could be used as a valuable selection criterion in breeding programmes aimed at enhancing disease resistance.

Karnal bunt of wheat (Triticum aestivum L.), caused by Tilletia indica, poses a persistent threat to grain quality, seed trade and production stability. The present study was undertaken to assess the spatial distribution of Karnal bunt over two consecutive Rabi seasons (2021–22 and 2022–23) and identify resistant genotypes suitable for cultivation in the north-western Himalayan region. Hundred genotypes were evaluated under artificially induced epiphytotic field conditions. Of these, four genotypes (IC416075, IC145334, IC572925 and IC279616) exhibited complete resistance, recording 0.00% disease incidence and coefficient of infection. Forty-two genotypes were resistant, forty-six were moderately susceptible, six susceptible and two highly susceptible. Genotype × environment (G × E) interaction analysis, including AMMI and stability regression models, identified HD-1105, PBW-803 and PBW-824 as stable performers across environments. Hierarchical clustering and Mahalanobis distance analysis further highlighted substantial genetic divergence among the test genotypes. The findings underscore the significance of integrating field surveillance with resistance screening to identify stable, disease-resistant genotypes for effective management of Karnal bunt in vulnerable wheat-growing regions.

In Malaysia, four species of Colletotrichum, namely C. fioriniae, C. scovillei, C. fructicola and C. truncatum, have been identified as the causal pathogens of chilli anthracnose. In this study, we assessed the potential of cross infection of C. fioriniae, C. scovillei, C. fructicola and C. truncatum on banana, mango and tomato fruits. The most virulent species seems to be isolates of C. fioriniae, and tomato was the most susceptible host. The results of the pathogenicity test showed the risk of cross-infection of the four species of Colletotrichum from chilli fruits with bananas, mangoes and tomatoes. The presence of wounds on fruits enhances the pathogenic potential of Colletotrichum. Identifying the host range of Colletotrichum spp. is essential for developing disease management strategies and efficient quarantine protocols.

Blast disease significantly hampers finger millet production and causes considerable yield reductions. This research aimed to assess the prevalence and severity of finger millet blast in the major finger millet-growing districts of Northwestern Amhara. Field surveys were carried out in 270 farmer fields across five districts during the main growing seasons from September to November in 2022 and 2023. Blast disease was identified in all surveyed districts, with different incidence levels affected by agroecological conditions, farming methods, and crop varieties. Incidence rates varied from 15.21% to 58.26%, with Siemen Achefer showing the highest mean incidence of 56.54%, while Dangila had the lowest value of 17.69%. The overall average incidence across all districts was 33.54%. The severity of the disease also differed significantly, ranging from 18.24% to 86.98%. The highest severity has been recorded in Jabi Tehnan district, with an average severity of 65.38%. Conversely, the lowest mean severity was scored in Takusa, with a mean of 36.16% with the overall average severity of 51.50% across all districts. Variations in cultivars, crop management practices and agroecological factors may have influenced the intensity of blast disease. The findings highlight the significant threat that blast disease poses to finger millet cultivation in the studied areas. The rising incidence and severity of the disease indicate a growing risk of significant yield losses. Consequently, immediate measures are required to establish effective management strategies for blast control to improve finger millet production and productivity.

Potyvirus musae (Banana bract mosaic virus, BBrMV), a member of the genus Potyvirus, can cause yield losses of up to 70% and is considered an important quarantine pathogen in international banana germplasm exchange. With the global movement of banana germplasm having increased in recent years, there is an urgent need for effective and scalable diagnostic tools for BBrMV detection in Taiwan. In this study, the recombinant BBrMV coat protein was expressed in Escherichia coli and used as an antigen to produce monoclonal antibodies. A specific monoclonal antibody, E9C11, was developed, and the optimal sampling strategy and extraction buffer were also established. The E9C11-based ELISA assay demonstrated sufficient sensitivity and specificity for large-scale indexing applications, including seedling certification and quarantine inspection. Furthermore, a field survey was conducted to understand the current infection status of BBrMV in Taiwan. The results indicated a low prevalence of BBrMV in commercial banana production areas, suggesting that the virus is not yet widespread but remains a potential threat. This study provides both a practical diagnostic tool and updated epidemiological data for effective BBrMV management in Taiwan.

This study explores the long-term effectiveness and stability of silver nanoparticles (AgNPs) synthesised using Ipomoea carnea extract against Rhizoctonia solani. AgNPs were stored under four conditions: room temperature (25°C) with light exposure, room temperature in darkness, 4°C in light and at 4°C in darkness; their antifungal activity was assessed over 360 days. AgNPs stored at 4°C in the dark showed sustained antifungal activity, while light exposure accelerated their degradation, reducing effectiveness by 120 days. UV–vis spectroscopy, particle size analysis and zeta potential confirmed increased nanoparticle oxidation due to light exposure. Under a higher concentration of NaCl (3 M), polyvinylpyrrolidone (PVP) and polyethylene glycol (PEG) were evaluated as stabilising agents. PVP exhibited the best protection against aggregation of AgNPs, followed by PEG. PVP offered superior protection against aggregation and maintained stability for up to 270 days, particularly at 4°C in darkness. Zeta potential analysis showed a moderate decline in nanoparticle stability over time, with PVP-stabilised AgNPs retaining a range of −28.7 to −22.1 mV. Antifungal assays demonstrated over 91.4% efficacy of PVP-stabilised AgNPs for 270 days, highlighting their potential as long-term antifungal agents. This study emphasises the importance of storage conditions and stabilisers in maintaining the efficacy of biosynthesised AgNPs.