Journal of Phytopathology最新文献

The olive tree (Olea europaea L.) is considered one of the most important fruit-producing crops across the Mediterranean Basin. Despite its importance, this crop remains vulnerable to infection by root-knot nematodes, Meloidogyne spp., and only a few cultivars with partial resistance to these nematodes have been identified. This study aimed to determine the response of olive cultivars to M. javanica infection. Six cultivars (Koroneiki, Arbequina, Arbosana, Picholine Marocaine, Menara and Haouzia) were infected with 1500 s-stage juveniles (J2s) per 1 kg of soil. Morpho-physiological metrics and M. javanica reproduction [final population, reproduction factor (RF)] were assessed after 9 months of incubation in the greenhouse. Morphological and physiological metrics were not affected by nematode infection, except for plant height, which was reduced for the Koroneiki cultivar. Regarding nematode reproduction, Koroneiki and Arbosana cultivars had significantly higher final populations (Pf > 300 per 100 g soil) and reproductive factors (RF > 2). In contrast, Menara and Arbequina recorded the lowest Pf (< 40) and RF (< 0.3). The Picholine Marocaine variety showed intermediate susceptibility, with reproductive parameters between those of the resistant and susceptible varieties. Overall, Menara, Arbequina and Haouzia were resistant to M. javanica, whereas Koroneiki and Arbosana were highly susceptible, with Picholine Marocaine showing an intermediate response.

Trichoderma species are widely recognised for their antagonistic activity against phytopathogenic fungi and for their ability to promote plant growth, hence representing promising candidates for sustainable crop protection. In this study, a Trichoderma gamsii isolate was recovered from the phyllosphere of hazelnut (Corylus avellana) and characterised through morphological, molecular and phylogenetic approaches. Its antagonistic potential was evaluated in vitro against six Colletotrichum species using dual culture assays, as well as through exposure to volatile and non-volatile metabolites. To elucidate the chemical basis of its antagonism, volatile organic compounds (VOCs) and non-volatile metabolites (non-VOCs) produced in pure culture were profiled by gas chromatography–mass spectrometry (GC–MS) and liquid chromatography–mass spectrometry (LC–MS/MS), respectively. The isolate exhibited strong inhibitory effects, reducing pathogen growth by up to 79%, depending on the Colletotrichum species. These results expand current knowledge of the metabolic repertoire of T. gamsii and support its potential as an effective and eco-friendly biocontrol agent for the sustainable management of anthracnose diseases.

Cassava mosaic disease (CMD) is a major constraint on cassava production in Tanzania. Although numerous efforts have targeted whitefly (Bemisia tabaci) control to curb CMD, results have been unsatisfactory. This study assessed the relative influence of whitefly transmission versus cassava variety resistance on CMD spread. The survey was conducted in two wards of Bagamoyo District. We randomly sampled 30 fields, and in each field evaluated four 10 m² plots (2743 plants). Four cassava varieties were recorded across the fields. Overall CMD prevalence was 45%, with only 16% of infections linked to whitefly and 84% with no evidence of whitefly. Landrace varieties (58%) had a 2-fold higher CMD risk compared to improved ones (25%). Specifically, disease incidence was 56% and 62% in landraces versus 21% and 28% in improved varieties. These findings indicate that varietal choice plays a significant role in the management of CMD. We recommend further studies that may employ molecular techniques, widen the geographic scope, more parameters and replications to improve CMD detection and statistical reliability.

Root-knot nematodes (Meloidogyne), with their broad host range and ability to challenge plant resistance, represent a significant obstacle to the development of crop production, including eggplant cultivation. In this greenhouse study, the resistance of 26 eggplant varieties to M. javanica was evaluated. The plant seeds were sown in two-kilogram plastic pots and kept under greenhouse conditions at a temperature of 27°C ± 2°C. The seedlings were inoculated at the four-leaf stage with 6000 nematode eggs. After 60 days, the plants were harvested, and the indices of plant growth and nematode populations were evaluated. In addition, catalase, peroxidase, and superoxide dismutase activity were measured. For this purpose, the varieties Noorabad and Black Beauty, which are highly sensitive and less sensitive varieties, respectively, were planted in one-kilogram pots and kept in the greenhouse. The seedlings were inoculated with 3000 nematode eggs at the four-leaf stage. Root tissue extraction was performed at six time points (0, 5, 9, 13, 17 and 21 days) after inoculation. The results showed that the growth indices of the varieties Faselis and Black Beauty were better compared to the other varieties. The significant changes in enzyme activity observed in the Black Beauty variety in response to infection were considered to be the reason for the lower nematode damage. However, according to the Canto-Saenz classification, all varieties analyzed were classified as susceptible, as they had a gall index > 2 and a reproduction factor > 1.

False Broomrape disease affects tobacco crops, causing stem galls and root tumours. In Cuba, soil-borne Nocardia spp. have been identified as its causal agents. This study evaluated the pathogenicity of Nocardia isolates, originally obtained from tobacco, on cabbage, a crop widely cultivated in Cuba. Four Nocardia spp. strains were inoculated into the roots of cabbage cv. ‘King of King's Cross’ seedlings. After 6 weeks, inoculated plants developed characteristic disease symptoms, including fasciated masses, aborted shoots and severe root inhibition. Strain T42 was the most aggressive phytopathogenic strain of Nocardia spp. to the ‘KKC’ cultivar of cabbage, followed by Cab37 and Yar21, while Jiq06 was less aggressive. To the best of our knowledge, this is the first worldwide report of cabbage as an experimental host for Nocardia spp., the causal agents of false Broomrape disease in tobacco in Cuba. Our findings reveal a new experimental host for these pathogens, with critical epidemiological implications for Cuba, where cabbage is frequently cultivated in rotation or proximity to tobacco, underscoring the urgent need for integrated disease management strategies.

Plant-derived phytochemicals have shown promise for inhibiting viral replication, driving research into novel botanical antivirals. This study evaluated the antiviral activity of yarrow (Achillea millefolium L.) hydroalcoholic extract (HAEx) and essential oil nanoemulsion (EON) at concentrations of 0.5%, 1%, 2% and 4% applied at different times relative to inoculation against cucumber mosaic virus (CMV) on non-systemic (Vigna unguiculata; cowpea) and systemic (Cucurbita pepo; pumpkin) hosts under greenhouse conditions. HPLC-DAD analysis identified chlorogenic acid (140.34 mg/g dry weight) as the predominant phenolic compound, while GC–MS analysis revealed 1,8-cineol (25.35%) as the major essential oil component. A stable EON was prepared with an average particle size of 264 nm after 60 days' shelf life. Key findings include that 2%–4% HAEx or EON applied 2 h post-inoculation significantly reduced local lesions in cowpea, whereby the strongest inhibition was achieved by 4% EON (59.82% lesion inhibition). Treatment with major active ingredients showed maximal inhibition with 8 mg/mL 1,8-cineole applied 2 h post-inoculation. In addition, 4% EON reduced CMV accumulation by 63.68% as shown via DAS-ELISA in pumpkin. Furthermore, 4% EON significantly increased total phenolic content along with phenylalanine ammonia-lyase, ascorbate peroxidase, peroxidase and catalase activities in CMV-infected pumpkin relative to controls. These results suggest that the application of yarrow HAEx and EON extracts may interfere with CMV replication and induce systemic resistance in cowpea and pumpkin plants. To our knowledge, this is the first report on the antiphytoviral activity of A. millefolium, supporting its further evaluation for plant virus management.

Stemphylium lycopersici is one of the major pathogens causing tomato leaf spot disease and its conidial sporulation in vitro can be a challenge in the research on this fungus. With this study, eight isolates of S. lycopersici were identified by the multi-sequence phylogenetic analysis of internal transcribed spacers 1 and 2 and intervening 5.8S nr DNA, glyceraldehyde-3-phosphate dehydrogenase, and calmodulin. The effect of their culture media, mycelial scraping, mycelial age, moisture content, plate sealing on the sporulation of various S. lycopersici isolates in vitro, as well as the dynamics of sporulation (one isolate only) were also evaluated. The conidiospore production assay was performed under specific conditions. Two-day-old mycelia were scraped and cultivated without Parafilm sealing at 15°C in continuous darkness. Under these conditions, all eight isolates produced over 100 conidiospores per mm². The type of culture medium and moisture level had no significant effect on the sporulation. The method derived from the study should provide sufficient conidiospores of S. lycopersici for further research in this field.