Phytopathology最新文献

Wheat stripe rust, caused by the biotrophic fungal pathogen Puccinia striiformis f. sp. tritici (Pst), is among the top crop diseases incurring huge economic losses worldwide. Identification of new stripe rust-resistant sources that can be easily used in wheat cultivar development is essential for food security. PI 622129, an Iranian wheat landrace, exhibits high resistance to the predominant U.S. Pst races. A recombinant inbred line (RIL) population from the cross PI 622129 × Stardust was genotyped using single-nucleotide polymorphisms generated by genotyping-by-sequencing. The RIL population was evaluated for responses to the Pst race PSTv-37 at the seedling stage in three environments, and quantitative trait loci (QTLs) analysis revealed four QTLs for stripe rust resistance on chromosome arms 2DS, 5BS, 2AL, and 7BL. Of these, QYr.stars-2DS and QYr.stars-5BS are major QTLs that explained 21 to 38% and 11.6 to 27.2% of the total phenotypic variance, respectively, in three experiments. QYr.stars-2DS is a new stripe rust resistance locus that was identified in the interval of 2.58 to 5.54 Mb on chromosome arm 2DS based on the Chinese Spring IWGSC RefSeq v.2.1 reference genome. Another QTL, QYr.stars-5BS, is close to Yr47 and was delimited to the interval 8.1 to 9.0 Mb in the reference genome. QYr.stars-2AL and QYr.stars-7BL were mapped to the terminal and QTL-rich regions on chromosome arms 2AL (750.8 to 752.5 Mb) and 7BL (718.1 to 721.2 Mb), respectively. KASP markers were developed to facilitate rapid introgression of these QTLs into locally adapted lines via marker-assisted selection.

Cathaya argyrophylla, a relict species endemic to China in the Pinaceae family, is classified as endangered on the IUCN Red List of Threatened Species. As a rare and endangered plant classified under Grade I protection in China, C. argyrophylla possesses significant scientific reference value. Needle cast caused by the fungal pathogen Neofusicoccum parvum is one of the most prevalent diseases affecting C. argyrophylla, leading to needle discoloration and necrosis, which poses a serious threat to its growth. Currently, there is a lack of effective biological control methods for this disease. In this study, we isolated an endophytic bacterium, Bacillus proteolyticus X6-1, from healthy needles of C. argyrophylla. This strain demonstrated a 65.5% inhibition of N. parvum in vitro. The pot experiment demonstrated that after inoculation with B. proteolyticus X6-1, the disease incidence and index of needle cast in C. argyrophylla were reduced by 42 and 20.3%, respectively. Given its potential efficacy against needle cast in C. argyrophylla, we employed coculture techniques alongside transcriptomics and high-throughput sequencing to elucidate the biological control mechanisms of strain X6-1. Furthermore, X6-1 enhanced the photosynthetic activity and antioxidant enzyme levels of C. argyrophylla. Inoculation with the B. proteolyticus strain further altered the phyllosphere microbiome by promoting the enrichment of beneficial microorganisms while decreasing the abundance of Neofusicoccum spp. Transcriptomic analysis revealed that B. proteolyticus regulates key biological pathways associated with growth in C. argyrophylla. Moreover, strain X6-1 produces protease and β-glucanase enzymes, which may contribute to its antifungal activity. Collectively, these findings suggest that B. proteolyticus may serve as an effective biocontrol agent for managing needle cast in C. argyrophylla.

Fungal pathogens have dramatically altered forests worldwide, yet the mechanisms of virulence remain poorly understood. From the 1970s to the early 2000s, dogwood anthracnose, caused by Discula destructiva, devastated North American flowering and Pacific dogwoods (Cornus florida and C. nuttallii, respectively), causing one of the most destructive forest tree epidemics of the modern era. Despite its ecological impacts, genomic resources for D. destructiva and related Diaporthales pathogens remain limited, thus hindering efforts to resolve the mechanisms of pathogenicity. Here, we present the telomere-to-telomere genome assembly of D. destructiva, complemented by transcriptome profiling to investigate gene expression shifts across its hemibiotrophic life cycle. The 46.655-Mb assembly comprised eight chromosomes with 99.47% BUSCO completeness, along with 10,373 predicted gene models with 97.40% BUSCO completeness. To profile life cycle-specific gene expression, we conducted RNA sequencing of sporulating (reproductive) and nonsporulating (vegetative) tissue and identified 240 differentially expressed genes (Padj < 0.05). Of those, 162 upregulated sporulation genes were associated with plant cell wall degradation and sugar metabolism, whereas 78 downregulated sporulation genes were associated with oxidative stress response and metal ion homeostasis. Of the 240 sporulation genes, 117 genes also encoded predicted virulence factors, including signal peptides, carbohydrate-active enzymes (CAZymes), and effectors. These patterns suggest a metabolic reallocation accompanying the transition to sporulation, which reflects physiological adaptation in response to environmental factors. Together, these findings illuminate the hemibiotrophic adaptation of D. destructiva and provide high-quality genomic tools for future comparative and functional studies. [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.

Spatial heterogeneity influences processes in agriculture and can be configured optimally for production and disease management. Landscape composition can be analyzed to infer sources of inoculum or vectors influencing points of interest such as crop fields and to estimate risk to improve management. Substantial research in plant ecology and disease epidemiology has addressed the importance of the dispersal kernel to spatial epidemic dynamics, but a methodological knowledge gap remains for situations in which the magnitude of dispersal from different landscape types varies. This knowledge gap is important to the study of emerging pathosystems in which inoculum sources or reservoirs may not be well characterized, as well as to vectored-disease systems in which transmitting arthropods are polyphagous with unknown host preference. Using simulated data, we describe issues that arise from the practice of summarizing spaces as concentric rings to infer dispersal kernels or identify influential landscape classes, and we demonstrate the utility of instead analyzing variation at a point of interest as a sum of simultaneously distance- and class-weighted remote sources. Of particular interest are scenarios in which the form of the true dispersal kernel is unknown and the goal is to rank landscape types depending on their magnitude of influence. The results emphasize that nonlinear regression methods are necessary for simultaneously fitting distance-weighting functions and estimating the relative influence of landscape types, and they show that ring-based descriptions of landscapes for analysis can lead to misapprehensions about dispersal processes. Methodological development is needed in plant disease epidemiology research in which dispersal kernels may vary depending on biological considerations.

Xanthomonas arboricola pv. pruni (XAP) causes bacterial spot in Prunus, and copper sprays have been widely used to manage this disease. Copper tolerance (≥150 µg/ml of copper sulfate pentahydrate [CSP]) is commonly found in XAP populations, but copper resistance (>200 µg/ml of CSP) has not been previously reported. This study reports and characterizes the first copper-resistant strain of XAP (XAPCuR), which was isolated from diseased leaves of Prunus laurocerasus in North Carolina in 2017. Whole-genome sequence analysis of XAPCuR revealed an approximately 247-kb plasmid carrying a duplicated 17-kb cluster containing copper resistance candidate genes copL, copA, copB, copC, copD, copM, copG, copF, cusA, and cusB. The two copies of the copper resistance cluster did not increase the level of copper resistance compared with a single copy, but deletion of both copies led to the loss of resistance. Functional analysis of the cluster revealed that copL-D is the major contributor to copper resistance, allowing XAP to grow on nutrient agar containing up to 750 µg/ml of CSP. Removing copL from copL-D decreased the resistance level to 300 µg/ml of CSP. The copF and cusAB genes alone did not confer copper resistance; however, adding copF-cusB to copL-D increased the resistance level of XAP to 1,000 µg/ml of CSP. The resistance genotype and phenotype were able to be transferred from XAP to Xanthomonas perforans via conjugation. This plasmid has up to 99% identity to other copper resistance plasmids of closely related xanthomonads, indicating that horizontal transfer is driving its spread.

Stripe rust and powdery mildew are serious diseases that significantly reduce wheat yield. Distant hybridization between wheat and its related species to develop disease-resistant translocation lines is an effective method for enhancing wheat's disease resistance. However, many newly developed disease-resistant wheat-related species translocation lines are difficult to use in wheat breeding because of their poor agronomic traits. Therefore, developing translocation lines that are resistant to diseases and have good agronomic traits is key for further use in wheat breeding programs. In this study, five novel T2AS.2RL translocation lines were developed from a cross between a high-yield wheat cultivar, CN25, and a Chinese rye landrace, Qinling. The results of cytogenetics and molecular analyses indicated that all five lines contained a pair of T2AS.2RL translocation chromosomes. These T2AS.2RL lines were highly resistant to stripe rust and powdery mildew. Genetic analysis indicated that resistance to stripe rust and powdery mildew was conferred by the 2RL chromosome arms derived from Qinling. In addition, compared with their high-yielding wheat parent CN25, these translocation lines presented good agronomic traits and no significant difference in yield. These results indicate that these new T2AS.2RL lines have great potential for use in future wheat breeding programs.

Root-lesion nematodes of the genus Pratylenchus, which includes over 100 species, are among the most damaging plant-parasitic nematodes, affecting a wide range of crops globally. Their migration in and out of roots causes mechanical damage and necrosis, leading to significant yield losses worldwide. In this study, we generated high-quality genome assemblies for three Pratylenchus species, P. penetrans, P. crenatus, and P. neglectus, isolated from potato fields across Canada. Using in silico analyses, we performed comprehensive genome annotation, comparative gene family analysis, and life-stage-specific gene expression profiling to investigate candidate genes likely involved in host interactions. Horizontal gene transfer (HGT) events were also predicted using the Alienness vs Predictor tool, based on protein homology comparisons and phylogeny between metazoan and non-metazoan taxa. These analyses revealed unique genomic structures, expansions of effector genes, and putative HGT events that may contribute to parasite adaptability. Notably, in P. crenatus and P. penetrans, the diversification and expansion of effector repertoires, combined with species-specific HGT candidates, could suggest evolutionary adaptations to support a broad host range. In contrast, the more compact effectorome of P. neglectus points to a parasitic strategy based on broad acting effectors. Although these findings provide an initial genome-scale view of the molecular toolkit used by these nematodes, they are based on computational predictions and await functional validation. This study lays a foundation for future research into the molecular mechanisms underlying parasitism, host adaptation, and nematode evolution.

Despite advances in modeling and sensing, no study has previously integrated mechanistic, meteorological, and uncrewed aerial vehicle (UAV) data into a unified predictive framework for Cercospora leaf spot. From 2020 to 2022, field trials with a susceptible variety under contrasting fungicide regimes and artificial inoculation were monitored for disease severity, airborne inoculum, and yield. Significant treatment differences emerged 44 days after sowing, with incubation lasting 7 to 12 days and spore peaks occurring from day 77, preceding rapid severity increases. Dissemination showed no prevailing direction but was favored by light, variable winds under conducive microclimates. Yield loss reached up to 0.0123 kg root fresh weight per plant per severity point, and both yield and sugar content decreased with earlier onset and higher final severity. Hybrid models were implemented at multiple levels, integrating multisource data. Severity was best predicted by climatic variables with UAV spectral-structural indices; fructification by humidity-temperature thresholds with stress traits; dissemination by wind-variability metrics with sporulation indicators; and yield and sugar content by UAV indices supplemented with mechanistic covariates. High-level hybridization reduced the root mean square error to 0.615 (on a 0 to 10 severity scale), 0.067 ng of Cercospora beticola DNA for actual spores, 2.033 ng for cumulative spores, 1.769° for dissemination direction, 0.015 ng day^-1 for dissemination magnitude, 0.235% for sugar content, and 0.051 kg plant^-1 for root fresh weight, achieving up to a 39% improvement over lower-level configurations. These results enhance disease prediction, improve the understanding of disease epidemiology, and could support more effective plant disease management. [Formula: see text] Copyright © 2026 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.

Plants defend themselves from viral infection using RNA interference (RNAi), an evolutionarily conserved mechanism that degrades viral RNA through the production of small interfering RNAs. As a counter defense, viral suppressors of RNA silencing (VSRs) inhibit plant RNAi machinery, aiding viral replication and transmission. P0, a VSR encoded by the potato leafroll virus (PLRV), family Polerovirus, suppresses RNAi by targeting the plant protein ARGONATE 1 for degradation through its F-box motif interaction with an Skp1 subunit of the family of E3 ubiquitin ligases. Our previous work shows that PLRV P0 suppresses antiviral immunity in its aphid vector Myzus persicae, leading to an increase in aphid infection by the insect virus Myzus persicae densovirus (MpDNV). Here, we expand on these findings and show that the P0 protein also regulates aphid fecundity. Using a series of F-box mutants, we demonstrate that a functional P0 F-box motif is required for inhibition of MpDNV antiviral immunity but not modulation of aphid fecundity. We further show that silencing suppressors from non-aphid-borne plant viruses that target other components of the plant's RNAi machinery also modulate aphid fecundity but not MpDNV titer. Collectively, the results show that aphids are favored by selection to modulate their antiviral immunity and fecundity in response to changes in plant RNAi pathways induced by plant viral infection. These data highlight the intricate co-evolution of plant viruses, their vectors, and host defenses. This knowledge may open new avenues for managing vector-borne plant diseases by targeting viral proteins to manipulate insect vectors.

Lettuce big-vein disease (LBVD) is a major disease affecting lettuce cultivation worldwide. LBVD is caused by two unrelated negative-stranded RNA viruses, Mirafiori lettuce big-vein virus (MiLBVV; Ophiovirus mirafioriense; Aspiviridae) and lettuce big-vein associated virus (LBVaV; Varicosavirus lactucae; Rhabdoviridae), both vectored by the soilborne fungus Olpidium virulentus. Despite extensive research, a synergistic effect between the two viruses has not been observed, whereas both viruses individually have been suggested to be the causal agent for the disease. By performing lettuce reinfections using a large soil sample collection carrying LBVD-infested O. virulentus spores, the presence of LBVaV was consistently established in diseased lettuce heads, whereas MiLBVV infections were apparently less prevalent. However, aboveground infections with MiLBVV corresponded with strong disease symptoms. Strikingly, the spread of LBVaV from the root to shoot always preceded that of MiLBVV. The LBVaV systemic spread was highly synchronized between plants, whereas MiLBVV spread was always delayed and asynchronous. A pangenome analysis revealed independent segment reassortments for both viruses, indicative of mixed field infections over the sampled period. However, RNA segment abundance was highly conserved for both viruses between all reinfections, suggesting that segment abundance has a regulatory role for the two individual viruses but is not impacted by the presence of the other two viruses. The pangenome analysis also revealed different evolutionary rates of the viral open reading frames, suggesting that mutagenesis of certain open reading frames compromises viral fitness and thus revealing a potential weak spot for both viruses.