Phytopathology最新文献

{"title":"Engineered Pine Endophytic Fungus Expressing dsRNA Targeting Lethal Genes to Control the Plant Parasitic Nematode <i>Bursaphelenchus xylophilus</i>.","authors":"Wei Zhang, Ruijiong Wang, Yongxia Li, Dongzhen Li, Xuan Wang, Xiaojian Wen, Yuqian Feng, Zhenkai Liu, Shuai Ma, Xingyao Zhang","doi":"10.1094/PHYTO-07-24-0203-R","DOIUrl":"https://doi.org/10.1094/PHYTO-07-24-0203-R","url":null,"abstract":"<p><p>The pine wood nematode (PWN), <i>Bursaphelenchus xylophilus</i>, is one of the most serious invasive forest pests, responsible for pine wilt disease (PWD). Currently, there are no effective, environmentally friendly control methods available. RNA interference (RNAi) technology has been extensively utilized to screen functional genes in eukaryotes and to explore sustainable pest management approaches through genetic engineering. In this study, we identified 353 predicted lethal genes in PWN by comparing its genome with those of lethal genes from <i>Caenorhabditis elegans</i>. We selected five predicted lethal genes (<i>Bxy1177</i>, <i>Bxy1239</i>, <i>Bxy1104</i>, <i>Bxy667</i>, and <i>BxyAK1</i>) with identification values exceeding 60% to evaluate their nematicidal effects on PWN. We tested the double-stranded RNA (dsRNA) of these genes using two methods: firstly, soaking in a synthesized dsRNA solution in vitro, or secondly, feeding on a dsRNA-engineered endophytic fungus, <i>Fusarium babinda</i>. Following dsRNA ingestion, either through soaking or fungal feeding, the expression of genes <i>Bxy1177</i>, <i>Bxy667</i>, <i>Bxy1104</i>, and <i>BxyAK1</i> was significantly suppressed. Notably, nematode populations that consumed fungi expressing dsL1177 and dsAK1 showed substantial declines over time. These findings provide novel insights and a practical foundation for employing endophytic fungi-expressed dsRNA in sustainable pest management strategies.</p>","PeriodicalId":20410,"journal":{"name":"Phytopathology","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142882781","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":"A nitrogen-metabolism inhibitor NmrA regulates conidial production, melanin synthesis and virulence in phytopathogenic fungus <i>Verticillium dahliae</i>.","authors":"Qi Xiao, Leyuan Zhang, Xueping Xu, Renyu Dai, Yingqing Tan, Xianbi Li, Dan Jin, Yanhua Fan","doi":"10.1094/PHYTO-07-24-0226-R","DOIUrl":"https://doi.org/10.1094/PHYTO-07-24-0226-R","url":null,"abstract":"<p><p>NmrA homologs have been reported as conserved regulators of the nitrogen metabolite repression (NMR) in various fungi. Here, we identified a NmrA homolog in <i>Verticillium dahliae</i> and reported its functions in nitrogen utilization, growth and development, and pathogenesis. VdNmrA interacts with <i>V. dahliae</i> AreA protein and regulates the expression of a typical NCR target, the formamidase gene. <i>VdNmrA</i> deletion mutants exhibited significantly slower colony growth on media with Gln or Arg. Furthermore, <i>VdNmrA</i> deletion impaired hyphal growth, spore production, hyperosmotic stress tolerance, and melanin biosynthesis. Less ROS was produced in <i>VdNmrA</i> mutants, and the NADPH oxidase genes <i>noxA</i> and <i>noxB</i> showed lowered expression level compared to the wild type. <i>VdNmrA</i> mutants exhibited reduced virulence on cotton and <i>Arabidopsis</i> compared with wild type strains. Our results indicated that VdNmrA functioned as an NMR repressor and played important roles in nutrient utilization, fungal development, stress tolerance and pathogenicity in <i>V. dahliae</i>.</p>","PeriodicalId":20410,"journal":{"name":"Phytopathology","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142838758","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":"<i>Rhizopus stolonifer</i> exhibits necrotrophic behavior when causing soft rot in ripe fruit.","authors":"Saskia Desiree Mesquida-Pesci, Abraham Morales-Cruz, Silvia Rodriguez-Pires, Rosa Figueroa-Balderas, Christian James Silva, Adrian Sbodio, Elia Gutierrez-Baeza, Petros Martin Raygoza, Dario Cantu, Barbara Blanco-Ulate","doi":"10.1094/PHYTO-03-24-0081-R","DOIUrl":"https://doi.org/10.1094/PHYTO-03-24-0081-R","url":null,"abstract":"<p><p><i>Rhizopus stolonifer</i> is known for causing soft rot in fruit and vegetables during postharvest. Although it has traditionally been considered a saprophyte, it appears to behave more like a necrotrophic pathogen. In this study, we propose that <i>R. stolonifer</i> invades host tissues by actively killing host cells and overcoming the host defense mechanisms, as opposed to growing saprophytically on decaying plant matter. We tested this hypothesis by characterizing <i>R. stolonifer</i> infection strategies when infecting four fruit hosts (tomato, grape, strawberry, and plum). We started by generating a high-quality genome assembly for <i>R. stolonifer</i> using PacBio sequencing. This led to a genome size of 45.02 Mb, an N50 of 2.87 Mb, and 12,644 predicted loci with protein-coding genes. Next, we performed a transcriptomic analysis to identify genes that <i>R. stolonifer</i> preferentially uses when growing in fruit versus culture media. We categorized these infection-related genes into clusters according to their expression patterns during the interaction with the host. Based on the expression data, we determined that <i>R. stolonifer</i> has a core infection toolbox consisting of strategies typical of necrotrophs, which includes a set of 33 oxidoreductases, 7 proteases, and 4 cell wall degrading enzymes to facilitate tissue breakdown and maceration across various hosts. This study provides new genomic resources for <i>R. stolonifer</i> and advances the knowledge of <i>Rhizopus</i>-fruit interactions, which can assist in formulating effective and sustainable integrated pest management approaches for soft rot prevention.</p>","PeriodicalId":20410,"journal":{"name":"Phytopathology","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142838700","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":"Pink-pigmented variant of <i>Clavibacter michiganensis</i> expands phenotypic range of tomato bacterial canker pathogen.","authors":"Malihe Haghverdi, S Mohsen Taghavi, Sadegh Zarei, Hamzeh Mafakheri, Hamid Abachi, Martial Briand, Geraldine Taghouti, Perrine Portier, Marie-Agnes Jacques, Ebrahim Osdaghi","doi":"10.1094/PHYTO-07-24-0236-R","DOIUrl":"https://doi.org/10.1094/PHYTO-07-24-0236-R","url":null,"abstract":"<p><p>Bacterial canker of tomato caused by the Gram-positive corynebacterial species <i>Clavibacter michiganensis</i> is one of the most destructive seed-borne diseases in both open air and greenhouse tomatoes. The pathogen is a regulated agent in all tomato-producing countries as translocation of infected tomato materials transports the bacterium into new areas. <i>Clavibacter michiganensis</i> is generally known to have yellow-pigmented colonies on culture media, which is a key differentiative phenotypic feature in standard diagnostic guidelines. During 2020 and 2021, pink-pigmented corynebacterial strains were isolated from tomato seeds (cv. Sun 6189F1) and plants showing severe canker symptoms in Southern Iran. The six pink-pigmented strains were pathogenic on tomato and pepper seedlings under greenhouse conditions, and gave positive results with <i>C. michiganensis</i>-specific primers pairs described in the literature. Phylogenomics and DNA similarity calculations showed that the pink-pigmented strains were highly similar to the authentic yellow-pigmented members of the pathogen. Thus, they were identified as a new phenotypic variant of tomato bacterial canker pathogen. Whole genome screenings accomplished with PCR-based assays showed that the pink strains contain all pathogenicity determinant genes described in <i>C. michiganensis</i>. Further, orthologous gene clusters in the pink-pigmented strains were more similar to the pathogenic members of <i>C. michiganensis</i> than to those of non-pathogenic tomato-associated <i>Clavibacter</i> species. Results obtained in this study demonstrate the emergence of a new pink-pigmented variant of <i>C. michiganensis</i> and highlight the importance of colony pigmentation/morphology in culture-based detection of the bacterium. The need for updating diagnostic guidelines on the colony variants of the pathogen is further discussed.</p>","PeriodicalId":20410,"journal":{"name":"Phytopathology","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142802074","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":"A qPCR Assay for the Quantification of the Overwintering Chasmothecia of <i>Erysiphe necator</i> in Grapevine Bark.","authors":"Othmane Taibi, Margherita Furiosi, Maela León, Elisa González-Domínguez, Vittorio Rossi, Mónica Berbegal","doi":"10.1094/PHYTO-04-24-0126-R","DOIUrl":"https://doi.org/10.1094/PHYTO-04-24-0126-R","url":null,"abstract":"<p><p>Powdery mildew (PM) disease causes serious losses in Mediterranean vineyards, where suitable environmental conditions promote conidial infections. The frequency and intensity of these infections are directly linked to the amount of primary <i>Erysiphe necator</i> inoculum, i.e., the chasmothecia embedded in the trunk. In this study, we set up a protocol to extract and quantify <i>E. necator</i> chasmothecia in grapevine bark samples based on a quantitative polymerase chain reaction (qPCR) assay. Moreover, we observed PM severity and ascocarp production on leaves in the first season and primary infection in the following season in different grapevine cvs. with known PM susceptibility levels. The qPCR analysis showed a significant relationship between <i>E. necator</i> DNA concentration in bark samples and primary infection (R² = 0.970) and disease severity development (R² = 0.776), as well as chasmothecia development on leaves (R² = 0.455). The results demonstrate that this methodology can be used for quantifying chasmothecia, improving current methods based on visual counting, proving the interrelationships between PM epidemics and chasmothecia, as well as refining PM disease prediction models and subsequent fungicide application. Rapid and easy quantification of ascosporic inoculum will greatly facilitate the reconciliation of control actions to the risks posed by greatly differing levels of ascosporic inoculum.</p>","PeriodicalId":20410,"journal":{"name":"Phytopathology","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142786803","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 <i>Pinus massoniana</i>'s Defense Mechanisms Against <i>Bursaphelenchus xylophilus</i> Under Aseptic Conditions: A Transcriptomic Analysis.","authors":"Jinghui Zhu, Kean-Jin Lim, Tianyu Fang, Chen Zhang, Jianren Ye, Li-Hua Zhu","doi":"10.1094/PHYTO-06-24-0180-R","DOIUrl":"10.1094/PHYTO-06-24-0180-R","url":null,"abstract":"<p><p>Pine wilt disease (PWD) is caused by the pine wood nematode (PWN, <i>Bursaphelenchus xylophilus</i>) and significantly impacts pine forest ecosystems globally. This study focuses on <i>Pinus massoniana</i>, an important timber and oleoresin resource in China, which is highly susceptible to PWN. However, the defense mechanism of pine trees in response to PWN remains unclear. Addressing the complexities of PWD, influenced by diverse factors such as bacteria, fungi, and environment, we established a reciprocal system between PWN and <i>P. massoniana</i> seedlings under aseptic conditions. Utilizing combined second- and third-generation sequencing technologies, we identified 3,718 differentially expressed genes post PWN infection. Transcript analysis highlighted the activation of defense mechanisms via stilbenes, salicylic acid and jasmonic acid pathways, terpene synthesis, and induction of pathogenesis-related proteins and resistance genes, predominantly at 72 h postinfection. Notably, terpene synthesis pathways, particularly the mevalonate pathway, were crucial in defense, suggesting their significance in <i>P. massoniana</i>'s response to PWN. This comprehensive transcriptome profiling offers insights into <i>P. massoniana</i>'s intricate defense strategies against PWN under aseptic conditions, laying a foundation for future functional analyses of key resistance genes. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.</p>","PeriodicalId":20410,"journal":{"name":"Phytopathology","volume":" ","pages":"2525-2535"},"PeriodicalIF":2.6,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142293751","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":"Characterization of Siderophores Produced by <i>Bacillus velezensis</i> YL2021 and Its Application in Controlling Rice Sheath Blight and Rice Blast.","authors":"Youzhou Liu, Chen Dai, Yang Zuo, Junqing Qiao, Jiahui Shen, Xiaole Yin, Yongfeng Liu","doi":"10.1094/PHYTO-04-24-0148-R","DOIUrl":"10.1094/PHYTO-04-24-0148-R","url":null,"abstract":"<p><p><i>Bacillus velezensis</i> YL2021 has extensive antimicrobial activities against phytopathogens, and its genome harbors a catechol-type siderophore biosynthesis gene cluster. Here, we describe the characterization of siderophores produced by strain YL2021 and its antimicrobial activity in vitro and in vivo. A few types of siderophores were detected by chrome azurol S plates coupled with Arnow's test, purified, and identified by reversed-phase high-performance liquid chromatography. We found that strain YL2021 can produce different antimicrobial compounds under low-iron M9 medium or iron-sufficient Luria-Bertani medium, although antimicrobial activities can be easily observed on the two media as described above in vitro. Strain YL2021 can produce at least three catechol-type siderophores in low-iron M9 medium, whereas no siderophores were produced in Luria-Bertani medium. Among them, the main antimicrobial siderophore produced by strain YL2021 was bacillibactin, with <i>m/z</i> 882, based on the liquid chromatography-tandem mass spectrometry analysis, which has broad-spectrum antimicrobial activities against gram-positive and gram-negative bacteria, the oomycete <i>Phytophthora capsici</i>, and phytopathogenic fungi. Moreover, the antifungal activity of siderophores, including bacillibactin, observed in vitro was correlated with control efficacies against rice sheath blight disease caused by <i>Rhizoctonia solani</i> and rice blast disease caused by <i>Magnaporthe oryzae</i> in vivo. Collectively, the results demonstrate that siderophores, including bacillibactin, produced by <i>B. velezensis</i> YL2021 are promising biocontrol agents for application in rice disease control.</p>","PeriodicalId":20410,"journal":{"name":"Phytopathology","volume":" ","pages":"2491-2501"},"PeriodicalIF":2.6,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142081325","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":"Genotypic and Phenotypic Analyses Show <i>Ralstonia solanacearum</i> Cool Virulence Is a Quantitative Trait Not Restricted to \"Race 3 Biovar 2\".","authors":"Ronnie J Dewberry, Parul Sharma, Jessica L Prom, Noah A Kinscherf, Tiffany Lowe-Power, Reza Mazloom, Xuemei Zhang, Haijie Liu, Mohammad Arif, Michael Stulberg, Lenwood S Heath, Kellye Eversole, Gwyn A Beattie, Boris A Vinatzer, Caitilyn Allen","doi":"10.1094/PHYTO-06-24-0187-R","DOIUrl":"10.1094/PHYTO-06-24-0187-R","url":null,"abstract":"<p><p>Most <i>Ralstonia solanacearum</i> species complex strains cause bacterial wilts in tropical or subtropical zones, but the group known as race 3 biovar 2 (R3bv2) is cool virulent and causes potato brown rot at lower temperatures. R3bv2 has invaded potato-growing regions around the world but is not established in the United States. Phylogenetically, R3bv2 corresponds to a subset of the <i>R. solanacearum</i> phylotype IIB clade, but little is known about the distribution of the cool virulence phenotype within phylotype IIB. Therefore, genomes of 76 potentially cool virulent phylotype IIB strains and 30 public genomes were phylogenetically analyzed. A single clonal lineage within the sequevar 1 subclade of phylotype IIB that originated in South America has caused nearly all brown rot outbreaks worldwide. To correlate genotypes with relevant phenotypes, we quantified virulence of 10 <i>Ralstonia</i> strains on tomato and potato at both 22 and 28°C. Cool virulence on tomato did not predict cool virulence on potato. We found that cool virulence is a quantitative trait. Strains in the sequevar 1 pandemic clonal lineage caused the most disease, whereas other R3bv2 strains were only moderately cool virulent. However, some non-R3bv2 strains were highly cool virulent and aggressively colonized potato tubers. Thus, cool virulence is not consistently correlated with strains historically classified as the R3bv2 group. To aid in the detection of sequevar 1 strains, this group was genomically delimited in the LINbase web server, and a sequevar 1 diagnostic primer pair was developed and validated. We discuss implications of these results for the R3bv2 definition.</p>","PeriodicalId":20410,"journal":{"name":"Phytopathology","volume":" ","pages":"2468-2480"},"PeriodicalIF":2.6,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142056319","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":"A Gene Cassette <i>Vd276-280</i> in <i>Verticillium dahliae</i> Contains Two Genes that Affect Melanized Microsclerotium Formation and Virulence.","authors":"Tao Liu, Haonan Yu, Jun Qin, Wenjing Shang, Jieyin Chen, Krishna V Subbarao, Xiaoping Hu","doi":"10.1094/PHYTO-11-23-0426-R","DOIUrl":"10.1094/PHYTO-11-23-0426-R","url":null,"abstract":"<p><p><i>Verticillium dahliae</i> is a soilborne phytopathogenic fungus causing Verticillium wilt on hundreds of plant species. Several sequenced genomes of <i>V</i>. <i>dahliae</i> are available, but functional characterization of most genes has just begun. Based on our previous comparison of the transcriptome from the wild-type and Δ<i>VdCf2</i> strains, a significant upregulation of the gene cassette, <i>Vd276-280</i>, in the Δ<i>VdCf2</i> strain was observed. In this study, the functional characterization of the <i>Vd276-280</i> gene cassette was performed. <i>Agrobacterium</i>-mediated knockout of this gene cassette in <i>V. dahliae</i> significantly inhibited conidiation, melanized microsclerotium formation in the mutant strains, and their virulence toward cotton. Furthermore, deletion of individual genes in the <i>Vd276-280</i> gene cassette identified that the disruption of <i>VDAG_07276</i> and <i>VDAG_07280</i> delayed microsclerotium formation, inhibited conidiation, and reduced virulence toward cotton. Our data suggest that <i>VDAG_07276</i> and <i>VDAG_07280</i> in the <i>Vd276-280</i> gene cassette mainly act as positive regulators of development and virulence in <i>V. dahliae</i>.</p>","PeriodicalId":20410,"journal":{"name":"Phytopathology","volume":" ","pages":"2515-2524"},"PeriodicalIF":2.6,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141983040","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":"Untargeted Metabolomic Analysis Reveals a Potential Role of Saponins in the Partial Resistance of Pea (<i>Pisum sativum</i>) Against a Root Rot Pathogen, <i>Aphanomyces euteiches</i>.","authors":"Ravinder K Goyal, Joseph P M Hui, Jeffrey Ranches, Roumiana Stefanova, Alysson Jones, Arjun H Banskota, Ian Burton, Bianyun Yu, Fabrice Berrue, Albert Hannig, Shawn Clark, Syama Chatterton, Sangeeta Dhaubhadel, Junzeng Zhang","doi":"10.1094/PHYTO-04-24-0151-R","DOIUrl":"10.1094/PHYTO-04-24-0151-R","url":null,"abstract":"<p><p>In soilborne diseases, the plant-pathogen interaction begins as soon as the seed germinates and develops into a seedling. <i>Aphanomyces euteiches</i>, an oomycete, stays dormant in soil and is activated by sensing the host through chemical signals present in the root exudates. The composition of plant exudates may, thus, play an important role during the early phase of infection. To better understand the role of root exudates in plant resistance, we investigated the interaction between partially resistant lines (PI660736 and PI557500) and susceptible pea cultivars (CDC Meadow and AAC Chrome) against <i>A. euteiches</i> during the pre-invasion phase. The root exudates of the two sets of cultivars clearly differed from each other in inducing oospore germination. PI557500 root exudate not only had diminished induction but also inhibited the oospore germination. The contrast between the root exudates of resistant and susceptible cultivars was reflected in their metabolic profiles. Data from fractionation and oospore germination inhibitory experiments identified a group of saponins that accumulated differentially in susceptible and resistant cultivars. We detected 56 saponins and quantified 44 of them in pea root and 30 from root exudate; the majority of them, especially soyasaponin I and dehydrosoyasaponin I with potent in vitro inhibitory activities, were present in significantly higher amounts in both roots and root exudates of PI660736 and PI557500 compared with Meadow and Chrome. Our results provide evidence for saponins as deterrents against <i>A. euteiches</i>, which might have contributed to the resistance against root rot in the studied pea cultivars. [Formula: see text] Copyright © 2024 His Majesty the King in Right of Canada, as represented by the Minister of Agriculture and Agri-Food Canada and the National Research Council of Canada. This is an open access article distributed under the CC BY 4.0 International license.</p>","PeriodicalId":20410,"journal":{"name":"Phytopathology","volume":" ","pages":"2502-2514"},"PeriodicalIF":2.6,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142056320","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}