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X-WR-CALDESC:Events for Department of Plant Pathology
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DTSTART;TZID=America/Los_Angeles:20260302T161000
DTEND;TZID=America/Los_Angeles:20260302T170000
DTSTAMP:20260626T145212
CREATED:20260127T225839Z
LAST-MODIFIED:20260306T203449Z
UID:3718-1772467800-1772470800@plantpath.wsu.edu
SUMMARY:Eric Holmes (guest speaker from University of Idaho)
DESCRIPTION:Study\, evolution\, and engineering of plant-microbe interactions to address emerging agricultural challenges.\nAbiotic and biotic stressors pose a significant threat to agriculture and global food security. As a rising demand for food and negative impacts from these stressors co-occur\, transformational changes to our agricultural systems will be necessary to efficiently feed the planet. New technologies that leverage the plant microbiome to improve depleted soils\, reduce crop loss\, and augment energy-intensive fertilizers promise to contribute toward this transformation\, yet additional mechanistic insight into plant-microbe interactions is necessary to fully exploit this potential. In the Holmes Lab\, we seek to define these molecular mechanisms and apply our insights to engineer microbial bioproducts that improve plant health and fitness. In this seminar\, I will present two case studies that exemplify this approach. First\, I will describe our work discovering and characterizing N-hydroxypipecolic acid\, a previously unknown plant hormone that is essential for systemic immune defense. Second\, I will discuss my prior industry work where we translated new biochemical insights into the development of a more effective bacterial anticancer vaccine. Together\, these examples highlight how mechanistic understanding of cross-kingdom biological systems can be harnessed to design impactful engineered bioproducts. \nEric’s Bio\nDuring his graduate work in Elizabeth Sattely’s lab at Stanford University\, Eric developed metabolic and genetic screening approaches to discover and engineer metabolite-based pathogen defense mechanisms in plants. Post-PhD\, Eric spent several years in industry\, working with microbiome therapeutic startups to develop novel genetic engineering strategies for bacterial-based therapeutics. He then transitioned to a Postdoctoral Researcher position at the National Renewable Energy Laboratory\, where he worked in Gregg Beckham’s group to develop strategies for producing sustainable food products from waste resources. In 2025\, Eric started his lab at the University of Idaho\, where he leverages expertise in plant chemistry\, metabolomics\, microbiology\, and synthetic biology to uncover and engineer the mechanisms that underlie critical interactions between plants and microbes. Eric was born and raised in Oregon and spends his spare time enjoying the Pacific Northwest’s many recreational opportunities. In particular\, he enjoys backpacking\, fly fishing\, wildlife photography\, running\, and vegetable gardening. \n 
URL:https://plantpath.wsu.edu/event/eric-holmes-guest-speaker-from-university-of-idaho/
LOCATION:Clark 151\, Pullman\, WA
CATEGORIES:2026 Spring Semester
ORGANIZER;CN="Melissa%20Bills":MAILTO:melissa.bills@wsu.edu
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/Los_Angeles:20260309T161000
DTEND;TZID=America/Los_Angeles:20260309T170000
DTSTAMP:20260626T145212
CREATED:20260127T225925Z
LAST-MODIFIED:20260323T144745Z
UID:3720-1773072600-1773075600@plantpath.wsu.edu
SUMMARY:Francely Flores
DESCRIPTION:Title: Modes of seed transmission of plant pathogens and their epidemiological importance\nZoom Recording \nBio\nFrancely is currently a Ph.D. student in the Berry and Potato Pathology Program at the Mount Vernon Northwestern Washington Research and Extension Center. She earned her B.S. in Agricultural Engineering from EARTH University\, Costa Rica in 2020\, and her M.S. in Sustainable Tropical Agriculture from Zamorano University in Honduras in 2023. Her master’s research focused on the adaptability and yield performance of introduced tomato lines under greenhouse and open-field conditions in Honduras. She has completed international internships in the Dominican Republic and at the World Vegetable Center in Taiwan. Her current research focuses on the management of Verticillium dahliae\, a soilborne pathogen affecting potato and several crops in western Washington. In her free time\, she enjoys reading\, listening to music\, playing badminton\, and drinking coffee. \nAbstract\nSeeds are foundation for successful crop production. However\, seeds can also serve as an important source of primary inoculum for diseases and facilitate long-distance movement of plant pathogens [1\,2]. Plant pathogens may be associated with seeds externally through contamination occurring in the field or during storage\, or internally through infection of the embryo or  non-embryonic tissues such as the endosperm or perisperm\, where transmission to the emerging seedling is not necessarily assured [1\,3]. These different modes of pathogen transmission by seeds influence epidemiological risk and disease outcomes. \nAcross pathogen groups\, transmission mechanisms vary but can lead to similar epidemiological consequences. Bacterial pathogens such as Xanthomonas citri pv. fuscans and Xanthomonas phaseoli pv. phaseoli\, the causal agents of common bacterial blight of bean\, may occur on the seed surface or within internal seed tissues and initiate epidemics at infection frequencies as low as one infected seed per 10\,000 to 30\,000 seeds. Hence\, seed health and phytosanitary programs have set a zero tolerance level for this pathogen on bean seeds  [4\,5]. Fungal pathogens\, such as Fusarium circinatum\, which cause pitch canker disease of pine\, are often externally seed-borne. However\, they can still cause severe disease in forest systems due to high seedling mortality and latent infections\, allowing the pathogen to persist undetected during early vegetative growth\, particularly in nursery production of pine seedlings – a risk that has led to the implementation of quarantine and strict phytosanitary measures [6\,7]. In contrast\, seed transmission of plant viruses is biologically limited and typically requires infection happening during a narrow window of embryonic development [1\,8]. This form of transmission represents vertical transmission\, in which the pathogen moves from the parent plant into the seed embryo. Viruses such as pea seed-borne mosaic virus can infect embryo of the seed posing epidemiological risk\, with risk levels varying among host cultivars [9]. In addition\, certain nematodes\, including Ditylenchus dipsaci\, are true seed-transmitted plant pathogens that survive in seeds in a dormant state and introduced to new areas due to long distance movement of seed\, often prompting strict quarantine measures [10–12]. \nA low frequency of seed infection does not equate to low epidemiological importance. Global seed trade amplifies these risks by enabling repeated and long-distance movement of pathogens beyond the limits of natural dispersal\, while detection challenges at low infection levels complicate effective risk management [13\,14]. Although advances in diagnostics and seed health systems have improved phytosanitary protection\, important challenges remain\, including identification of detection limits of pathogens relative to epidemiological risk\, influence of environmental conditions on transmission dynamics\, and the need for improved risk-based decision frameworks that  link seed health test results to epidemiological and economic thresholds for phytosanitary decision-making [13\,14]. The objective of this seminar is to examine how seed transmission pathways influence epidemiological risk and disease management across different plant pathogen groups. \n Literature Cited\n\nBaker\, K.F.\, and Smith\, S.H. 1966. Dynamics of seed transmission of plant pathogens. Annu. Rev. Phytopathol. 4:311-332. https://doi.org/10.1146/annurev.py.04.090166.001523\nElmer\, W.H. 2001. Seeds as vehicles for pathogen importation. Biol. Invasions 3:263-271. https://doi.org/10.1023/A:1015217308477\nInternational Plant Protection Convention. 2025. International movement of seeds. https://www.ippc.int/en/publications/84340/\nEFSA Panel on Plant Health. 2014. Scientific opinion on the pest categorisation of Xanthomonas axonopodis phaseoli and Xanthomonas fuscans subsp. fuscans. EFSA J. 12:3856. https://doi.org/10.2903/j.efsa.2014.3856\nChen\, N. W. G.\, Ruh\, M.\, Darrasse\, A.\, Foucher\, J.\, Briand\, M.\, Costa\, J.\, Studholme\, D. J.\, and Jacques\, M.-A. 2021. Common bacterial blight of bean: A model of seed transmission and pathological convergence. Mol. Plant Pathol. 22:1464-1480. https://doi.org/10.1111/mpp.13067\nEvira-Recuenco\, M.\, Iturritxa\, E.\, Raposo\, R. 2015. Impact of seed transmission on the infection and development of pitch canker disease in Pinus radiata. Forests 6:3353-3368. https://doi.org/10.3390/f6093353\nEuropean and Mediterranean Plant Protection Organization 2019. PM 7/91 (2): Fusarium circinatum (formerly Gibberella circinata). Bull. OEPP 49:228-247. https://doi.org/10.1111/epp.12587\nWang\, D.\, and Maule\, A. J. 1994. A model for seed transmission of a plant virus: Genetic and structural analyses of pea embryo invasion by pea seed-borne mosaic virus. Plant Cell 6:777-787. https://doi.org/10.1105/tpc.6.6.777\nBeck-Okins\, A. L.\, del Río Mendoza\, L. E.\, Burrows\, M.\, Simons\, K. J.\, and Pasche\, J. S. 2022. Pea seed-borne mosaic virus risk analysis of field pea based on susceptibility\, yield loss\, and seed transmission. Plant Dis. 106:938-946. https://doi.org/10.1094/PDIS-06-21-1349-RE\nHolajjer\, P.\, Jadon\, K. S.\, Chandrawat\, B. S.\, and Gawade\, B. 2020. Seed-borne and seed-associated nematodes: An overview. Pages 355-368. in: Seed-Borne Diseases of Agricultural Crops: Detection\, Diagnosis & Management. R. Kumar\, and A. Gupta\, eds. Springer\, Singapore. https://doi.org/10.1007/978-981-32-9046-4_15\nGreen\, C. D.\, and Sime\, S. 1979. The dispersal of Ditylenchus dipsaci with vegetable seeds. Ann. Appl. Biol. 92:263-270. https://doi.org/10.1111/j.1744-7348.1979.tb03872.x\nEuropean and Mediterranean Plant Protection Organization. 2017. PM 7/87 (2) Ditylenchus destructor and Ditylenchus dipsaci. Bull. OEPP 47:401-419. https://doi.org/10.1111/epp.12433\nMunkvold\, G. P. 2009. Seed pathology: Progress in academia and industry. Annu. Rev. Phytopathol. 47:285-311. https://doi.org/10.1146/annurev-phyto-080508-081916\nMunkvold\, G.\, du Toit\, L.\, and Dunkle\, R. 2025. Seed pathology: Challenges and advances in ensuring a safe global seed supply. Annu. Rev. Phytopathol. 63:43-62. https://doi.org/10.1146/annurev-phyto-121423-093855\n\n 
URL:https://plantpath.wsu.edu/event/francely-flores/
LOCATION:Clark 151\, Pullman\, WA
CATEGORIES:2026 Spring Semester
ORGANIZER;CN="Melissa%20Bills":MAILTO:melissa.bills@wsu.edu
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BEGIN:VEVENT
DTSTART;TZID=America/Los_Angeles:20260316T161000
DTEND;TZID=America/Los_Angeles:20260316T170000
DTSTAMP:20260626T145212
CREATED:20260127T230526Z
LAST-MODIFIED:20260127T230526Z
UID:3722-1773677400-1773680400@plantpath.wsu.edu
SUMMARY:Spring Break
DESCRIPTION:No Seminar
URL:https://plantpath.wsu.edu/event/spring-break/
CATEGORIES:2026 Spring Semester
ORGANIZER;CN="Melissa%20Bills":MAILTO:melissa.bills@wsu.edu
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/Los_Angeles:20260323T161000
DTEND;TZID=America/Los_Angeles:20260323T170000
DTSTAMP:20260626T145212
CREATED:20260127T230610Z
LAST-MODIFIED:20260330T153435Z
UID:3723-1774282200-1774285200@plantpath.wsu.edu
SUMMARY:Elaine Larsen
DESCRIPTION:Elaine Larsen\nZoom Recording \nFungi as Vectors of Plant-Pathogenic Viruses\nViruses are the most abundant biological entity on Earth\, infecting all cellular organisms across terrestrial and marine ecosystems [1]. Plants are known to be infected by diverse viruses and viroids (i.e.\, virus-like\, unencapsidated\, single-stranded RNA particles) belonging to at least 35 families [2]. Several viral families contain structurally related viruses that infect either plants or fungi (i.e.\, mycoviruses)\, and several viral genera infect both plants and fungi [2]. The majority of research on plant viruses has focused on pathogenic viruses that cause disease in agricultural crops and account for the annual global loss of ca. $30 billion [3]. Plant pathogenic viruses are typically vectored by sap-sucking arthropods [4]\, but the potential for fungi to act as vectors for plant-pathogenic viruses was discovered as early as the 1970s\, when tobacco mosaic virus (TMV) was identified in the asexual spores (conidia) of a powdery mildew fungus [2]. Since then\, several plant viruses have been successfully inoculated into fungi and oomycetes\, with some resulting in stable infections [5-8]. Similarly\, studies have shown that viroids can infect yeasts ( Saccharomyces cerevisiae )\, plant-pathogenic filamentous fungi\, and the oomycete pathogen Phytophthora infestans [9-11]. Viroids also have been transmitted successfully between fungal hyphae via hyphal fusion and persist in spores after asexual reproduction [11]. Although plant viruses could exist within fungal cells\, they were not known to undergo replication [2]. However\, it is now recognized that some plant viruses and viroids can replicate within fungal cells\, suggesting that fungi may both vector and amplify viral loads [5-11]. Beyond simply being vectored by fungi\, viruses and viroids can modulate the pathogenicity of infected fungi [2]. In some cases\, the severity of plant disease caused by plant-pathogenic fungi has been shown to either increase or decrease when fungi are infected by plant viruses [7]. While most viroid infections appear to be asymptomatic in fungi\, hop stunt viroid (HSVd) reduced growth and pathogenicity in the plant-pathogenic fungus Valsa mali [11]. Mycoviruses may also reduce the pathogenicity of pathogenic fungi and have been researched as potential biological control agents [2\,12]. Virus-induced hypovirulence has been observed in Cryphonectria parasitica \, the causative agent of chestnut blight\, and Ophiostoma ulmi \, which causes Dutch elm disease [2\,12]. Demonstrating the potential for both pathogenic and non-pathogenic fungi to serve as vectors of pathogenic viruses\, a recent study found that fungal endophytes isolated from the leaves of plants exhibiting symptoms of viral infection carried a number of plant-pathogenic viruses [8]. Overall\, the long evolutionary history of close endosymbiotic relationships between plants and fungi—ranging from parasitic to mutualistic interactions—appears to have shaped the evolution\, host specificity\, and transmission of plant viruses [2]. However\, more research is needed to understand the role of pathogenic and non-pathogenic fungi in vectoring plant-pathogenic viruses and the implications of fungus-virus interactions on plant disease management.
URL:https://plantpath.wsu.edu/event/elaine-larsen/
LOCATION:Clark 151\, Pullman\, WA
CATEGORIES:2026 Spring Semester
ORGANIZER;CN="Melissa%20Bills":MAILTO:melissa.bills@wsu.edu
END:VEVENT
BEGIN:VEVENT
DTSTART;TZID=America/Los_Angeles:20260330T161000
DTEND;TZID=America/Los_Angeles:20260330T170000
DTSTAMP:20260626T145212
CREATED:20260127T230701Z
LAST-MODIFIED:20260406T162758Z
UID:3726-1774887000-1774890000@plantpath.wsu.edu
SUMMARY:Kylie Swisher Grimm (guest speaker from USDA)
DESCRIPTION:Improving our understanding of Tobacco rattle virus\nAbstract\nTobacco rattle virus causes internal and external tuber necrosis that render potatoes unmarketable. The virus is vectored to potato in the northwest U.S. by the stubby root nematode\, Paratrichodorus allius\, and commercial growers control the virus through costly chemical controls that target the nematode.  Basic research strategies have been conducted in the greenhouse to improve our understanding of virus movement within a plant and factors that influence nematode fecundity. Applied research strategies have been utilized in the field to identify strategies that growers might use to mitigate the effects of the virus on tuber yield and quality. As part of the Tri-State Potato Variety Development Program\, breeding clones are screened each year for resistance to Tobacco rattle virus-induced internal tuber necrosis. Information gained from each of these projects can combine to improve strategies that commercial growers currently use to mitigate Tobacco rattle virus and its nematode vector. \nAbout Kylie\nKylie Swisher Grimm is a Research Plant Pathologist at the USDA-ARS Temperate Tree Fruit and Vegetable Research Unit located in Prosser\, WA. Her research focuses on the epidemiology\, biology\, and management of new and emerging pathogens of potato and vegetable crops in the Northwestern U.S. One aspect of Dr. Grimm’s research focuses on insect-vectored pathogens such as ‘Candidatus Liberibacter solanacearum’ and ‘Candidatus Phytoplasma trifolii’ that are the causal agents of zebra chip and potato purple top diseases\, respectively. She has worked to identify novel pathogen haplotypes\, identify host plant and insect vector associations\, and develop new molecular tools for high-throughput insect testing. Another aspect of Dr. Grimm’s program focuses on soilborne pathogens that cause internal tuber necrosis such as Tobacco rattle virus and Potato mop-top virus that are vectored by stubby root nematodes and Spongospora subterranea\, respectively. Much of this work has been on understanding the relationship between pathogen\, host\, and vector\, as well as identifying disease-resistant germplasm that will benefit growers in the region. Dr. Grimm’s background in molecular biology pairs nicely with the field and greenhouse trials routinely conducted in her program. \nZoom Meeting Information\nZoom Link\nZoom Meeting ID: 959 0545 7360\nZoom Password: 2488
URL:https://plantpath.wsu.edu/event/kylie-swisher-grimm-guest-speaker-from-usda/
LOCATION:Clark 151\, Pullman\, WA
CATEGORIES:2026 Spring Semester
ORGANIZER;CN="Melissa%20Bills":MAILTO:melissa.bills@wsu.edu
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