Phytopathology最新文献

{"title":"Eriophyid Mites Vector the Kitavirus Blueberry Necrotic Ring Blotch Virus: Insights into the Viral Transmission and Its Infection on Blueberry Plants.","authors":"Aline Daniele Tassi, Pedro Luis Ramos-González, Carlos H W Flechtmann, James W Amrine, Ali Sarkhosh, Juliana Freitas-Astua, Elliot Watanabe Kitajima, João Paulo Rodrigues Marques, Philip F Harmon, Daniel Carrillo","doi":"10.1094/PHYTO-02-25-0063-R","DOIUrl":"10.1094/PHYTO-02-25-0063-R","url":null,"abstract":"<p><p>Blunerviruses, family <i>Kitaviridae</i>, infect and cause diseases of important crop plants, including tomato, tea, and blueberry. Despite their economic importance, the epidemiology of blunerviruses and the mechanisms of plant-to-plant transmission remain largely unknown. In 2006, the blunervirus blueberry necrotic ring blotch virus (BNRBV, <i>Blunervirus vaccinii</i>) was detected in Florida, United States, causing disease on blueberry plants and tentatively linked to an eriophyid mite vector. To gain insights into plant-virus interaction and plant-to-plant transmission of BNRBV, in this study, we investigated sap transmission and the potential vector of blueberry-infesting eriophyid and <i>Brevipalpus</i> mites collected in Florida during 2022 and 2023. Although kitaviruses are vectored by several species of <i>Brevipalpus</i> mites, our experiments revealed a distinct vector for BNRBV. Both mite types acquired the virus, but only viruliferous eriophyids of the species <i>Calacarus corymbosi</i>, described for the first time in this work, transmitted the virus. Assays for BNRBV mechanical transmission were unsuccessful. This study marks the first demonstration of a characterized pathogen vectored by a mite in the genus <i>Calacarus</i> within kitavirus. Upon transmission by the eriophyid mite, BNRBV caused characteristic local necrotic ring blotch symptoms in blueberry leaves, and the virus was detected in symptomatic tissues and also in roots, but only at 6 months after inoculation, suggesting restricted or inefficient long-distance movement of the virus within the plant. This paper introduces a model for investigating the transmission of blunerviruses, a rapidly growing group of plant viruses.</p>","PeriodicalId":20410,"journal":{"name":"Phytopathology","volume":" ","pages":"1038-1050"},"PeriodicalIF":3.1,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144045252","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Soil Temperature and Moisture Conditions Affect the Recovery and Sporulation Capacity of <i>Phytophthora ramorum</i> from Infested <i>Rhododendron</i> Leaf Disks.","authors":"Ebba K Peterson, Niklaus J Grünwald, Jennifer L Parke","doi":"10.1094/PHYTO-02-25-0056-R","DOIUrl":"10.1094/PHYTO-02-25-0056-R","url":null,"abstract":"<p><p>The invasive pathogen <i>Phytophthora ramorum</i> persists within nurseries, potentially within buried, infested leaf debris. To determine how the environment-notably soil temperature and moisture levels-affects the epidemiological risk of soil inoculum reserves, we performed laboratory assays assessing how variable conditions impact pathogen survival and its capacity to sporulate. We first established that incubating the inoculum at 4°C increases the number of sporangia produced from infested rhododendron leaf disks. In a second experiment, the inoculum was incubated in soil at a range of temperature (6.7, 14, 20, or 28°C) and soil moisture (approximately 0, -40, or -400 kPa) conditions for up to 18 weeks. Our ability to culture <i>P. ramorum</i> was only negatively affected by the warmest and driest regimes. In contrast, the capacity to sporulate was affected over a much wider range of conditions, whereby declines in sporulation potential were observed over time from the inoculum incubated at both 20 and 28°C in all soil moisture conditions. However, subsequent incubation of this inoculum at 4°C for an additional 7 weeks restored sporulation potential, at times exceeding pre-incubation levels. These results are consistent with field observations that <i>P. ramorum</i> becomes more biologically active after exposure to cooler temperatures and highlights the risk a soilborne inoculum poses during some times of the year. Disinfestation of soils through artificially high heat is likely required to prevent recurrent infections within nurseries from soilborne sources and thus prevent the further spread of this invasive pathogen.</p>","PeriodicalId":20410,"journal":{"name":"Phytopathology","volume":" ","pages":"968-977"},"PeriodicalIF":3.1,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144161408","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Host-Parasite Interaction in Flax Rust-Its Genetics and Other Implications.","authors":"H H Flor","doi":"10.1094/Phyto-45-680","DOIUrl":"10.1094/Phyto-45-680","url":null,"abstract":"<p><p>The pathogenicity of 67 F₂ cultures of a cross of race 6 with race 22 of the flax rust pathogen was determined on 32 varieties of flax that had been selected as carrying single genes for rust reaction. Two varieties were resistant and 6 were susceptible to all F₂ cultures. On 23 of the 24 varieties on which the F₂ cultures segregated for pathogenicity, the ratio of avirulent to virulent cultures approximated the 3:1 expected if virulence on each was conditioned by a pair of recessive genes. On Ottawa 770B, 2 pairs of genes may have conditioned pathogenicity. Fifty-four pathogenic races were identified from the 67 cultures. Host-parasite interaction in flax rust may be explained by assuming a gene-for-gene relationship between rust reaction in the host and pathogenicity in the parasite. Pustule type, the criterion of both reaction and pathogenicity, is conditioned by specific pairs of genes, one in the host and the other in the parasite. In flax and the flax rust fungus, 25 such pairs of genes have been identified. Because of the gene-for-gene relationship between reaction in the host and pathogenicity in the parasite, the recessive gene complement of a uredial clone (culture) is established by determining its pathogenicity on differential varieties with single rust-conditioning genes. The homozygosity or heterozygosity of the dominant genes is established by selfing the uredial clone. Thus, a method for identifying the pathogenic genotype of races of the rust fungi has been devised. This makes possible the use of the biotype as the basic concept of race. The gene-for-gene relationship of rust reaction and pathogenicity in host and parasite facilitates the development of rust-resistant varieties and opens new approaches to studies of the origin of new races, mutation for rust reaction in the host and pathogenicity in the parasite, and the evaluation of epidemiology data, and the nature of resistance.</p>","PeriodicalId":20410,"journal":{"name":"Phytopathology","volume":"115 8V","pages":"680-685"},"PeriodicalIF":3.1,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145041121","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Focus Expansion in Plant Disease. I: The Constant Rate of Focus Expansion.","authors":"F van den Bosch, J C Zadoks, J A J Metz","doi":"10.1094/Phyto-78-54","DOIUrl":"10.1094/Phyto-78-54","url":null,"abstract":"<p><p>According to theory, a focus of disease in a crop expands radially at a rate that asymptotically approaches a constant value. This value can be calculated from the time kernel, contact distribution, and gross reproduction. Time kernel describes the inoculum production through time and contact distribution describes inoculum dispersal. Gross reproduction is the total number of victimized individuals produced by a single infectant placed in a population consisting of suscepts only. Definitions and mathematical evidence are given.</p>","PeriodicalId":20410,"journal":{"name":"Phytopathology","volume":"78 1","pages":"54-58"},"PeriodicalIF":3.1,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"61193631","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Genomic Characterization of Plant Immune Receptor Genes Reveals the Role of Alfalfa <i>MsRLK725</i> in Salt Tolerance and Disease Resistance.","authors":"Xiaojuan He, Yuling Han, Jia Zhang, Zimo Zhu, Congzhuo Xu, Yuqin Qiang, Siqi Li, Tao Liu, Mingjiu Wang, Zhipeng Liu, Longfa Fang","doi":"10.1094/PHYTO-12-24-0408-R","DOIUrl":"10.1094/PHYTO-12-24-0408-R","url":null,"abstract":"<p><p>Plant immune receptor proteins, including pattern recognition receptors and nucleotide-binding domains and leucine-rich repeat sequence receptors (NLRs), are essential for various aspects of plant growth and development, including microbial sensing and immune responses. However, a comprehensive and systematic understanding of immune-related gene families in alfalfa plants is lacking. This study aimed to identify and characterize these genes in alfalfa to fill this knowledge gap. We identified 736 receptor-like kinase (<i>RLK</i>), 407 receptor-like protein (<i>RLP</i>), and 870 <i>NLR</i> genes in the alfalfa genome and analyzed their structural and genetic variation. Phylogenetic analysis classified <i>RLKs</i>, <i>RLPs</i>, and <i>NLRs</i> into 22, 21, and 3 subgroups, respectively. Chromosomal location and synteny analyses revealed that single-gene duplication events contributed to the evolution of these genes. Expression profiling, promoter cis-acting elements, and associated network analyses demonstrated their critical roles in plant growth and stress prevention. Specifically, the alfalfa <i>RLK</i> gene (<i>MsRLK725</i>) was selected for functional validation due to its numerous genetic variants and significant upregulation under biotic stress. Overexpression of <i>MsRLK725</i> in <i>Nicotiana benthamiana</i> enhanced resistance to <i>Rhizoctonia solani</i> and <i>Phoma medicaginis</i>, and the hairy root transient transformation system improved alfalfa's salt tolerance. Our findings offer valuable insights for future research on using immune-related genes in alfalfa, highlighting their potential in molecular breeding for stress tolerance and disease resistance.</p>","PeriodicalId":20410,"journal":{"name":"Phytopathology","volume":" ","pages":"924-937"},"PeriodicalIF":3.1,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144044541","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental Evolution of <i>Phytophthora infestans</i> on Tomato Reveals Rapid Genotypic and Phenotypic Adaptation and Dynamic RXLR Genome Variation.","authors":"Allison Coomber, David A Rasmussen, Jean Beagle Ristaino","doi":"10.1094/PHYTO-12-24-0401-R","DOIUrl":"10.1094/PHYTO-12-24-0401-R","url":null,"abstract":"<p><p>The late blight pathogen, <i>Phytophthora infestans</i>, poses a significant threat to tomato crops worldwide. To understand the potential for rapid adaptation of this pathogen, we conducted an in vitro experimental evolution study with four <i>P. infestans</i> US-23 lineages collected from tomato hosts with different combinations of resistance genes (<i>Ph</i> genes). These isolates were passed serially over eight generations on five tomato cultivars. After infection, targeted sequencing of the pathogen's RXLR effector genes was done. In just eight generations, we observed both phenotypic and genotypic changes in the US-23 lineages, with differences in disease severity among pathogen isolates and alterations in the RXLR genome. Our findings suggest rapid mutation even in a clonally reproducing lineage, highlighting the potential for adaptation of <i>P. infestans</i> within a single growing season on tomato. These insights shed light on the adaptability of this devastating pathogen and emphasize the importance of considering tomato host resistance in late blight management strategies.</p>","PeriodicalId":20410,"journal":{"name":"Phytopathology","volume":" ","pages":"998-1007"},"PeriodicalIF":3.1,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144033452","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Could Canola Canopy Architecture Affect Pathogen Infection by Impacting Flower Accumulation on Branches?","authors":"Elizabeth J Trevenen, Rodrigo N Pires, Stanley Mastrantonis, Michael Renton","doi":"10.1094/PHYTO-11-24-0377-R","DOIUrl":"10.1094/PHYTO-11-24-0377-R","url":null,"abstract":"<p><p><i>Sclerotinia sclerotiorum</i>, a fungal pathogen of canola (<i>Brassica napus</i>), can cause yield losses exceeding 20%. An important route for disease is through infected flowers falling and accumulating on branches, which act as a source of inoculum to infect the stems, resulting in stem rot, wilting, plant collapse, and, ultimately, yield loss. The branching architecture of canola may affect <i>Sclerotinia</i> infection by affecting flower accumulation in canopies; however, our understanding of this effect is limited. This study explored how changing canola canopy architecture affected <i>Sclerotinia</i> infection rates via flower fall within a simulated field setting. To investigate this, we created a new static structural model coupled with a novel model of flower fall that accounts for wind conditions. Upright architectures resulted in increased infection by positioning more flowers above axils, which increased flower accumulation on branches, whereas outstretched branching reduced infection by positioning fewer flowers above axils. However, no single architecture consistently resulted in the lowest infection rate across a range of wind conditions. The coupled functional-structural model helped dissect the effects of wind, crop plant architecture, number of infected flowers, and planting density on fungal infection in canola fields. This research suggests that manipulating plant architecture through lowering planting density or breeding could offer a simple and cost-effective strategy to help reduce <i>Sclerotinia</i> infection in canola fields. The results may have broader application to other crops for which infected flowers can act as a source of inoculum for stem disease.</p>","PeriodicalId":20410,"journal":{"name":"Phytopathology","volume":" ","pages":"1008-1017"},"PeriodicalIF":3.1,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144768950","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Systems Analysis and the Dynamics of Epidemics.","authors":"J C Zadoks","doi":"10.1094/Phyto-61-600","DOIUrl":"10.1094/Phyto-61-600","url":null,"abstract":"","PeriodicalId":20410,"journal":{"name":"Phytopathology","volume":"61 1","pages":"600-610"},"PeriodicalIF":3.1,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"61107793","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Unraveling the Environmental Drivers of <i>Phyllachora maydis</i> Spore Release and Dispersal Using Spore Trapping and qPCR.","authors":"Jill C Check, Janette L Jacobs, Peyton J Phillips, Emily M Roggenkamp, Jaime Willbur, Martin I Chilvers","doi":"10.1094/PHYTO-01-25-0027-R","DOIUrl":"10.1094/PHYTO-01-25-0027-R","url":null,"abstract":"<p><p><i>Phyllachora maydis</i>, the causal agent of tar spot of corn, is an emerging disease in the United States and Canada. This study aimed to improve our understanding of <i>P. maydis</i> spore release and dispersal by utilizing spore trapping and quantitative PCR to assess the relationship between spore capture and environmental conditions. Burkard and rotating-arm air samplers were deployed in Michigan corn fields with natural disease pressure from 2021 to 2023. Correlation analysis and mixed-effects logistic regression were applied to examine the impact of environmental factors on spore capture. Through an exhaustive screening of candidate logistic regression models, results indicated that spore quantity is significantly negatively correlated with daily summaries of minimum temperature (<i>P</i> < 0.05, τ = -0.24), mean temperature (<i>P</i> < 0.05, τ = -0.25), maximum precipitation rate (<i>P</i> < 0.05, τ = -0.33), and durations of temperature between 16.6 to 23°C and relative humidity over 85% (<i>P</i> < 0.001, τ = -0.27). Logistic regression models frequently incorporated temperature and humidity predictors, and the best performing model used daily averages of mean temperature and maximum humidity to discriminate between the presence and absence of spore detection, achieving a balanced accuracy of 85%. Across all site-years, spore traps did not detect <i>P. maydis</i> spores prior to the visible detection of tar spot symptoms but did detect spores before tar spot incidence reached 100%. Through this study, the environmental drivers of spore release and dispersal were described to fill current knowledge gaps in the tar spot disease cycle. Additionally, a methodology for the capture and molecular quantification of airborne <i>P</i>. <i>maydis</i> spores is described, which will benefit future research.</p>","PeriodicalId":20410,"journal":{"name":"Phytopathology","volume":" ","pages":"955-967"},"PeriodicalIF":3.1,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144079693","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Role of Microbial Activity in Suppression of Damping-Off Caused by <i>Pythium ultimum</i>.","authors":"Weidong Chen, A J Hoitink, A Fritz Schmitthenner, Olli H Tuovinen","doi":"10.1094/Phyto-78-314","DOIUrl":"10.1094/Phyto-78-314","url":null,"abstract":"<p><p>Addition of nutrients increased Pythium damping-off severity in a suppressive container medium amended with bark compost from the low temperature edge of a compost pile. A significant linear response of disease severity to added nutrients was observed. Levels of seed exudation were directly related to damping-off severity for seeds of a cucumber, a smooth-seeded, and a wrinkled-seeded pea cultivar. Container media amended with compost from the high temperature center of a compost pile (> 60 C) were conducive to the disease at first but became suppressive in 3 to 4 days after incubation at 25 C, as they became recolonized by mesophilic microorganisms. Initially concentrations of water extractible glucose, reducing sugars, and total carbohydrates in the center compost medium were higher than those in the edge compost medium. However, concentrations decreased to levels not significantly different from those in the edge compost medium after 1, 4, and 6 days, respectively. These reductions in carbohydrate concentrations coincided with an increase in suppression in the medium prepared with high temperature compost. This increase with time was highly correlated with microbial activity, based on rates of hydrolysis of fluorescein diacetate (<i>r</i>= -0.919, <i>P</i>< 0.001), and also correlated with total biomass, based on extractible phospholipid phosphate (<i>r</i>= -0.509, <i>P</i>< 0.003). Populations of mesophilic bacteria, actinomycetes, and total fungi in the conducive high temperature compost-amended medium were significantly lower in the first 2 days after incubation at low temperature. After 4 days, populations had increased to levels similar to those in the medium amended with low temperature compost, and they stayed at that level thereafter. Percent infection of cucumber and germination of <i>Pythium</i> sporangia were significantly higher in the conducive than in the suppressive container medium. Infection of cucumber occurred before <i>Pythium</i> populations increased significantly. It was concluded that coexistence of large populations of mesophilic microorganisms, great microbial activity, low concentrations of available nutrients, and high degree of microbiostasis characterized container media suppressive to Pythium damping-off.</p>","PeriodicalId":20410,"journal":{"name":"Phytopathology","volume":"78 1","pages":"314-322"},"PeriodicalIF":3.1,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"61193327","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}