Plant disease最新文献

Neoscytalidium dimidiatum (Penz.) Crous & Slippers, a major pathogen affecting dragon fruit production globally, has also been documented causing diseases on economic or landscape crops in many countries. Despite the wide geographical distribution and host range of the pathogen, knowledge of the genetic and biological characteristics of N. dimidiatum from different spatiotemporal and host populations is limited. This study compared the phylogenetic and phenotypic diversity of the N. dimidiatum populations collected from dragon fruit between 2010 and 2021 in Taiwan with the isolates obtained from other hosts and countries. A multilocus sequence analysis revealed that N. dimidiatum from Taiwan clustered based on their hosts, dragon fruit and cattleya, regardless of the spatiotemporal origins, whereas the isolates from other countries exhibited a slightly higher phylogenetic diversity. Limited phylogenetic diversity suggested that asexual reproduction may be the primary approach for N. dimidiatum to maintain the population in Taiwan. Nevertheless, variations in colony color, mycelial growth, and spore germination at different temperatures were evident within and among populations at different spatiotemporal scales. For instance, the population collected from dragon fruit in northwestern and eastern Taiwan had a significantly better mycelial growth rate at 40°C, compared with the populations collected from southwestern Taiwan. All tested isolates from different hosts were found to cause lesions on dragon fruit cladodes; however, generally larger lesions and significantly shorter latent periods were observed in the isolates collected from dragon fruit. The results suggested that phenotypic plasticity in clonal N. dimidiatum populations, along with a better fit in the original host and the potential of infecting hosts that were under heat or other abiotic stresses, may contribute to the global emergence of the pathogen.[Formula: see text] Copyright © 2026 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Oklahoma grapevine production interests are on the rise, however very little is known about the occurrence of major grapevine-infecting viruses in the state. To address this knowledge gap, a total of 85 grapevine samples were collected from eight vineyards across six counties in Oklahoma during the spring and fall of 2024. Total RNA extracts from each sample were assayed for 14 major viruses by RT-PCR, including grapevine leafroll-associated virus 1 (GLRaV-1), GLRaV-2, GLRaV-3, GLRaV-4, grapevine fanleaf virus (GFLV), grapevine red blotch virus (GRBV), tobacco ringspot virus, tomato ringspot virus, grapevine fleck virus, grapevine rupestris stem pitting-associated virus (GRSPaV), grapevine virus A (GVA), GVB, GVE, and GVH. Virus infection was detected in 68.2% of samples, with mixed infections (36.5%) being more common than single infections. Seven of the targeted viruses were detected at varying levels of incidences, including GRBV (48.2%), GRSPaV (40%) GLRaV-3 (20%), GFLV (11.8%), GVE (11.8%), GVA (5.9%), and GVH (2.4%). GRBV variants belonging to both clades I and II were identified in Oklahoma, with the clade II members being more predominant. Multigenic diversity assessments of GLRaV-3 isolates from Oklahoma showed the occurrence of variants belonging to both clades I and V, with the latter being more frequently detected in the state relative to results from other U.S. growing regions. The findings of the study underscore the importance of continued virus surveillance, use of clean plant materials, and targeted management strategies to protect Oklahoma's developing vineyards from the long-term impact of viral diseases.

Emergence of Xylella fastidiosa (Xf) in Europe threatens agriculture and natural ecosystems. Its adaptability to diverse environments raises concerns regarding potential host shifts and increased virulence. Effective disease management depends on accurate and timely detection. Additionally, understanding its interaction with local host cultivars is essential for developing risk mitigation measures. This study evaluated the pathogenicity and the extension of stem colonization of five Xf strains from different subspecies, isolated from almond and olive trees in Spain and Italy, inoculated on three widely cultivated Spanish olive cultivars. All strains successfully infected and colonized olive plants, although detection frequencies decreased over time, and none of the strains induced disease symptoms. Overall, strains XYL1961/18 and De Donno from subspecies pauca showed higher colonization frequencies and bacterial loads compared with strains from subspecies multiplex. Furthermore, physiological responses were assessed using leaf spectral data retrieved with handheld proximal sensors, enabling the calculation of 74 vegetation indices to detect physiological alterations linked to infection status in asymptomatic plants. Of the 74 indices, between 17 and 31, mainly related to pigment composition (carotenoids, flavonoids, and xanthophylls), were selected as reliable predictors (>90% accuracy) of infection status across strains and olive cultivars. This study highlights the importance of evaluating the extent of stem colonization and interactions among local olive cultivars and Xf strains from different subspecies. We showed that proximal sensing may offer a promising noninvasive tool for early detection and monitoring of Xf infection, supporting timely management, thereby reducing the risk of new outbreaks. These methodologies may also assist in breeding programs aimed at developing Xf-resistant olive cultivars.

Pythium pathogens commonly inhibit tobacco transplant production in float-bed style hydroponic greenhouses, but disease symptoms often vary. Results from 2018 to 2020 Petri dish and greenhouse "mini-bay" virulence assays found that the 12 Pythium spp. isolated in a 2017 tobacco greenhouse survey fell into three categories: aggressive, weak, or nonpathogens. P. myriotylum and P. coloratum were aggressive pathogens, always suppressing seedling stands and causing disease damage compared with the untreated control (P < 0.05). Seedling stands were almost always lower and disease incidence and severity were almost always greater for P. myriotylum versus the other Pythium species tested (P < 0.05). One of two isolates of P. dissotocum was also an aggressive pathogen, whereas the second isolate was a weak pathogen, rarely reducing plant stands or increasing damage compared with the untreated control (P < 0.05). P. irregulare usually reduced seedling stands more than the other weak pathogens (P. aristosporum, P. catenulatum, P. inflatum, P. porphyrae, and P. torulosum) but caused less disease less consistently than P. myriotylum, P. coloratum, and the more aggressive P. dissotocum isolate (P < 0.05). P. adhaerens, P. attrantheridium, and P. pectinolyticum were nonpathogens, failing to cause symptoms on tobacco seeds or seedlings. Variation in virulence among Pythium spp. was consistent across the virulence categories but sometimes varied among species within categories and was also usually consistent across inoculation dates. These results suggest variance in virulence among Pythium biotypes is likely a significant factor responsible for variability in Pythium disease in tobacco greenhouses.

Downy mildew, caused by the obligate pathogen Peronospora effusa, can have a devastating economic impact on spinach production. Growing resistant cultivars is the most economical way to manage this disease and the only viable management practice for organic spinach production. However, rapidly emerging races or novel strains may result in a breakdown of the resistance deployed. It is therefore critical to monitor the population dynamics of P. effusa and to determine the disease reactions of newly released cultivars to the new races and novel strains. In this study, 74 isolates of P. effusa were examined for their pathogenicity on differential host cultivars, resulting in the identification of three new races and 18 novel strains with unique virulence pathotypes. Of those identified, race 19 of P. effusa could infect many widely grown cultivars with resistance to P. effusa races 1 to 17. Targeted sequencing of DNA isolated from lesions of P. effusa race 19 isolates revealed genetic variations among isolates and within isolates of P. effusa race 19. The isolates showed either no genetic variation (only one genotype was found from multiple lesions of an isolate tested), limited, or abundant genetic variation (multiple genotypes were found within an isolate tested). Additionally, 70 commercial spinach cultivars were tested with two P. effusa races, 18 and 19, and four novel strains. The results of this study are helpful for growers in selecting suitable cultivars for production and for breeders in developing downy mildew-resistant cultivars.

Stripe rust is an important disease affecting wheat production around the world and poses a constant threat to yield. Discovery of new resistance genes is essential for long-term maintenance of resistance. This study used a group of 273 spring wheat landraces collected in northwest China to identify better sources of resistance to stripe rust. The landrace population was planted in five environments to assess adult plant resistance. Both genetic and environmental factors were associated with resistance variation. Several varieties, including Banjiemang, Gezanmai, and Datangsanyuemai, were found to be highly resistant in all environments. Population structure analysis divided the population into six subgroups, and there were significant differences in stripe rust resistance responses between these subgroups. A genome-wide association study (GWAS) was performed using two algorithms to balance the false negative and false positive rates. Eight reliable quantitative trait loci (QTL) and their candidate genes were detected on chromosomes 1B, 2B, 3B, 5A, 6D, and 7A. To determine the resistance of the identified QTL, we evaluated the seedling-stage infection responses of different genotypes to the stripe rust races CYR32 and CYR34. The pyramid effects of favorable alleles have been validated to improve resistance. The identified resistant varieties and QTL will be useful for further improving stripe rust resistance in wheat breeding.

Wheat streak mosaic disease (WSMD) is the most important viral disease affecting wheat production in the US Great Plains. WSMD is caused by a single or co-infection of wheat curl mite (WCM)-transmitted wheat streak mosaic virus (WSMV), Triticum mosaic virus (TriMV), and/or High Plains wheat mosaic virus (HPWMoV). Nebraska, one of the US Great Plains states, significantly contributes to the national small grain production and utilizes cereal crops as forage and cover crops. In this study, a state-wide sampling was conducted during the 2023-2025 growing seasons across Nebraska to examine the infection dynamics of the causal agents of WSMD in winter and spring cereal crops. A total of 1624 symptomatic leaf samples were assayed with multiplex RT-PCR. In 2024, co-infection of wheat with WSMV and TriMV was more common, whereas WSMV single infections dominated in 2023. In contrast, WSMV single infections were predominant in field oats compared to WSMV-TriMV coinfection. We found a high incidence of WSMV and TriMV as single and co-infections in other cereal and forage crops: rye (80%), triticale (93%), and barley (72%). HPWMoV was found only in a few wheat samples as co-infections with WSMV or WSMV+TriMV in 2023. The P1 and CP sequences of WSMV and TriMV from different cereal hosts showed minimal sequence diversity, indicating that these viruses circulate freely among diverse cereal hosts. Our data suggest that various commercial, forage, and cover cereal crops are infected with mite-transmitted viruses in field conditions and may serve as a green bridge for the continuum of WSMD in wheat.

Utilizing microbial biofertilizers has emerged as a viable alternative to enhance crop productivity in sustainable agriculture. Of the 378 endophytic strains from oil palm (Elaeis guineensis) and nibung palm (Oncosperma sp.), 168 strains exhibited phosphate solubilization indices (PSI: 1.47 to 4.37), and, within those isolates, 48 endophytes displayed indole-3-acetic acid (IAA) production (2.91 to 120.90 μg/ml). Culture filtrates from 14 strains with high PSI and IAA production were selected to assess their ability to increase seed germination of sweet and field corn. Eight of these endophytes significantly enhanced seed germination and seedling growth, particularly Daldinia eschscholtzii MFLUCC20-0215 (P ≤ 0.05). This fungal strain also promotes phosphorus availability, as soluble inorganic phosphate in the soil increased from 0.89 ± 0.14 to 2.74 ± 0.09 ppm after inoculation with this strain for 30 days. The total chlorophyll of corn leaves grown in nutrient-depleted (N.D.) soil inoculated with D. eschscholtzii MFLUCC20-0215 was higher than corn grown in N.D. soil (13.37 ± 2.20 μmol m^-2 compared with 5.10 ± 0.06 μmol m^-2). A microbial biofertilizer prototype was developed and used as inoculants in the soil for cultivating crops including tomato (Solanum lycopersicum), chili (Capsicum frutescens), lettuce (Lactuca sativa L.), red coral lettuce (Lactuca sativa var. crispa), and Chinese kale (Brassica oleracea). Significant differences were evident across all growth indexes of the tested crops when comparing our biofertilizer prototype and synthetic fertilizer to the negative control. Here, we present for the first time that nibung palm is a source of beneficial endophytic fungi in promoting plant growth. Our biofertilizer prototype will contribute to sustainable crop production systems by effectively enhancing crop production while minimizing environmental impacts.

Maximum likelihood (ML) phylogenies of 109 tymoviruses, including 3 obtained directly from metagenomes, were calculated from all three open reading frames separately, but the concatenated sequences of their replicase and coat protein genes gave the most representative trees. ML phylogenies were also calculated from all recorded tymovirus coat protein genes, and from datasets of the turnip yellow mosaic virus cluster, and separately of tomato blistering mosaic, Andean potato latent, and Andean potato mild mosaic viruses. These phylogenies showed that the basal divergence of tymoviruses occurred in a population infecting Eurasian brassicas (rosids), and more recently, one of the basal lineages diversified and adapted to infect some solanaceous (asterid) plants and crops of Central and South America. Heterochronous dating of the phylogenies failed, but heuristic comparisons based on patristic distances, branching patterns, and external events suggested that the "most recent common ancestor" of all known tymoviruses existed before the last Ice Age. Some lineages reached the Americas about 15,000 years ago. However, most of the spread of the few tymoviruses now found on more than one continent occurred during the past 2 centuries. The only recombinants were two sequences of chiltepin yellow mosaic virus, both with Nemesia ring necrosis virus as the minor parent. Population genetic analysis found significant evidence of population contraction in the tymovirus populations infecting asterid hosts in the Americas. It also found the replicase and coat protein genes were significantly negatively selected. By contrast, the overlapping movement protein genes were positively selected, which may help them adapt to new host species, including infecting economically significant crops. This knowledge about tymoviruses is important to plant biosecurity authorities.

Fusarium head blight (FHB) is a major wheat disease worldwide and is caused by multiple species of the Fusarium graminearum species complex (FGSC). In this study, we investigated the spatiotemporal dynamics of FGSC associated with Fusarium head blight (FHB) in wheat in Mexico from 2014 to 2023 by species and trichothecene chemotype characterization, ELISA-based mycotoxin quantification, and greenhouse virulence testing. A total of 975 isolates were collected, mainly from the Central Highlands of Mexico. In this study, the occurrence of F. graminearum sensu stricto (F. graminearum s.s.) was reported for the first time in Mexico. First identified in 2014, its occurrence showed an increasing trend over the years, accounting for 34.77% of the sampled isolates. F. boothii was the most frequent species, representing 54.46% of the isolates, though it exhibited a decreasing trend across time. In addition to these two species, this study identified eight F. meridionale isolates and 97 non-FGSC isolates. Sequence-Tagged Site (STS) and Kompetitive Allele-Specific PCR (KASP) markers were developed to effectively differentiate between F. graminearum s.s., F. boothii and F. meridionale. All three type B trichothecene chemotypes were identified among the F. graminearum s.s. isolates: 76.11% were of the 3-acetyldeoxynivalenol (3-ADON) chemotype, 23.60% were of the 15-acetyldeoxynivalenol (15-ADON) chemotype, and only one isolate belonged to the nivalenol (NIV) chemotype. The frequency of the 3-ADON chemotype increased over time. In vitro experiments revealed that this chemotype exhibited significantly higher DON productivity than the 15-ADON and NIV chemotypes, along with greater pathogenicity in greenhouse experiments. These findings highlight the importance of monitoring pathogen composition and chemotype prevalence changes for developing effective Fusarium management and resistance breeding strategies.