Journal of Phytopathology最新文献

Begomoviruses and associated betasatellite molecules significantly impact crop yields in Middle Eastern countries. Previously, cotton leaf curl Gezira virus (CLCuGeV, Begomovirus gossypigeziraense) and the associated betasatellite, okra leaf curl Oman betasatellite (OLCuOMB, Betasatellite abelmoschusomanense), were detected in okra farms in Jiroft, south-eastern Iran. The current study describes the interaction between OLCuOMB and okra leaf curl enation virus (OELCuV, Begomovirus abelsmoschusenation) in okra farms in the same region. Both OELCuV and OLCuOMB, along with the Gossypium darwinii symptomless alphasatellite (GDarSLA, Colecusatellite gossypiumdarwinii), were detected in okra plants, and a similar viral association with only GDarSLA was found in diseased basil plants. The full-length genomes of OELCuV isolates from okra and basil shared 99.4% nucleotide identity with each other, and > 97% with other Iranian isolates from papaya available in GenBank. To satisfy Koch's postulates, an infectious clone of OELCuV was constructed, and its pathogenicity was assessed with or without the OLCuOMB clone. Accordingly, agroinoculation with a combination of OELCuV and OLCuOMB resulted in more severe symptoms in okra plants compared to the milder symptoms produced following agroinoculation with the virus alone. The presence of alphasatellite and betasatellite molecules in association with various begomoviruses, and a turncurtovirus across different crops in south-eastern Iran indicates that geminivirus-satellite disease complexes are causing significant yield losses in this region.

Blackberry is one of the four most important commercial berries, along with raspberry, strawberry, and blueberry. Mexico is the world's leading producer of blackberries, accounting for 21.8% of the global total. In October 2023, severe symptoms of leaf anthracnose were observed in a commercial blackberry plantation in Zacatlán, Puebla, Mexico. Based on morphological features, the fungi isolated from the diseased plants were identified as members of the Colletotrichum acutatum species complex. The multilocus phylogeny (ITS, act, gapdh, his3, chs-1, and tub2) confidently classified the isolates as Colletotrichum godetiae. Artificial inoculation of healthy leaves led to symptom development after 7 days, thereby fulfilling Koch's postulates. This is the first global report of C. godetiae causing leaf anthracnose on blackberry (Rubus spp. var. Tupy). Leaf anthracnose in blackberry plantations in Puebla, Mexico, requires further studies to analyse the pathogen's diversity, its geographic distribution, and alternative hosts, all aimed at guiding surveillance efforts and developing management strategies.

Hostuviroid impedihumuli is a circular, positive-sense, single-stranded RNA viroid, 295–303 nucleotides in length, belonging to the family Pospiviroidae and the genus Hostuviroid. The most stable secondary structure of viroid RNA has been shown to adopt a rod-like or semi-rod-like conformation. A comprehensive study was conducted to detect viroids in walnut (Juglans regia) trees. A total of 230 walnut samples were collected from various provinces across Türkiye and subjected to molecular analysis. Both one-step real-time RT-PCR and conventional RT-PCR methods were employed, using primers specifically designed for the detection of H. impedihumuli. Molecular analyses revealed that 11.3% of the samples were infected with H. impedihumuli. The viroid sequences obtained were compared with homologous sequences in the GenBank database, showing nucleotide similarity rates ranging from 89.5% to 99.3%. To the best of our knowledge, this study presents the first documented occurrence of H. impedihumuli in walnut, representing a novel host record for both Türkiye and the global plant health community.

Since April 2020, a powdery mildew disease has been consistently observed on Plantago asiatica in northern India. Microscopic examination of the associated fungus revealed morphological characteristics typical of the genus Golovinomyces. Molecular identification based on a BLASTn similarity search of the internal transcribed spacer region, along with phylogenetic analyses using maximum likelihood, maximum parsimony, and Bayesian inference methods, confirmed the species as Golovinomyces sordidus. Pathogenicity was verified through inoculation of healthy P. asiatica plants. To the best of our knowledge, this is the first confirmed report of G. sordidus causing powdery mildew on P. asiatica in India.

Dragon fruit is an economically important crop in Mexico. In summer 2023, severe galling symptoms were observed in a plantation in the state of Puebla. This study aimed to identify the species of root-knot nematode responsible for this damage. Red dragon fruit plants, which showed symptoms of yellowing, stunted growth and severe root galling, were collected. A single egg mass extracted from the roots was used to inoculate Rio Grande tomato plants to obtain a pure population. Morphological, morphometric and molecular (based on 28 s rDNA) analyses were used to identify the nematode species. Host suitability was confirmed by inoculation tests. Based on the results, we identified Meloidogyne enterolobii as the nematode linked to the serious symptoms seen in the field. To our knowledge, this is the first report of M. enterolobii infesting dragon fruit plants in Mexico, and based on our observations, this nematode could pose a significant threat to the crop.

Silver nanoparticles are important because they have biological activity and physicochemical properties that make them useful. Silver, which is thought to be inert in nature, reacts with moisture in the skin and wound fluid to release ions, making it one of the most effective antimicrobial/antibacterial agents throughout history. However, this work illustrates the environmentally friendly production of silver nanoparticles (AgNPs) by employing leaf extract from Artemisia lerchiana as a stabilising and reducing agent. With a zeta potential of −20 mV and an average size of 165 nm, the biosynthesised AgNPs demonstrated stable colloidal characteristics. Gram-positive (Staphylococcus aureus, Bacillus subtilis), Gram-negative (Escherichia coli, Pseudomonas aeruginosa), and fungal (Candida albicans) strains were tested for antimicrobial efficacy. The results showed significant inhibitory effects, especially against Bacillus subtilis (MIC: 0.560 mg/mL) and C. albicans (MIC: 0.014 mg/mL). Additionally, using regression analysis, the ideal synthesis parameters were found to be 56°C, 6-unit extract, 2.4 mM AgNO₃, and an 8-min reaction time. These parameters produced AgNPs with improved antimicrobial activity (predicted MIC: 0.01 mg/mL). The results show that AgNPs mediated by Artemisia lerchiana have the potential to be an environmentally friendly antimicrobial agent, and they recommend more research into their mechanisms and potential uses in medicine.

Bacterial spot disease, caused by Xanthomonas euvesicatoria, poses a significant threat to pepper (Capsicum spp.) production, necessitating sustainable control strategies. This study aimed to isolate and evaluate beneficial bacteria from healthy pepper plants as biocontrol agents and plant growth promoters. A total of 344 epiphytic and 192 endophytic bacterial isolates were collected from pepper fields in Şanlıurfa and Adıyaman, Türkiye, and screened for antagonistic activity against X. euvesicatoria and plant growth-promoting traits. Fourteen isolates were selected for greenhouse trials, applied via seed treatment, foliar spray, or combined methods. Notably, this study is the first to report Acinetobacter lactucae UEP50 and Pseudarthrobacter polychromogenes AEND14 as novel BCAs against X. euvesicatoria in peppers, highlighting their potential as effective microbial agents. Acinetobacter lactucae UEP50 and Pseudarthrobacter polychromogenes AEND14 showed promising biocontrol efficacy, reducing disease severity by up to 85% in controlled greenhouse trials with combined seed and foliar treatments. The combined application method demonstrated superior efficacy compared to single applications, achieving a 30%–40% higher reduction in disease severity than seed or foliar treatments alone, suggesting a synergistic effect that enhances disease suppression and plant growth promotion. Further field studies are needed to confirm these results. These isolates also demonstrated strong antagonistic activity (inhibition zones up to 27 mm) and plant growth-promoting traits, including indole-3-acetic acid production (up to 126.92 μg/mL) and phosphate solubilisation. This study reports A. lactucae and P. polychromogenes as promising biocontrol agents against X. euvesicatoria in peppers, suggesting their potential role in integrated pest management. Further literature review is needed to confirm the novelty of this finding. These findings suggest potential for developing microbial-based strategies to enhance pepper production sustainability. However, further research is necessary to validate field efficacy and optimise application methods.