Location: Mycology and Nematology Genetic Diversity and Biology Laboratory
2022 Annual Report
Accomplishments
1. New downy mildew discovered on wild grapes in the United States. Downy mildew diseases are widespread, pervasive and can result in damage so great that the host’s value is reduced and/or the commodity is not marketable, yield is reduced, or the host is killed outright. Grape downy mildew caused by Plasmopara viticola is one of the most severe and destructive diseases of grapes, impacting both the yield and the quality of the harvested fruits and making it a major constraint for the grape industry. ARS scientists in Beltsville, Maryland, in collaboration with research scientists in Germany, identified the existence of different downy mildew in wild relatives of the cultivated grapes. The results of this study have important implications for viticulture, including breeding for resistance and disease management.
2. Genomic resources for Ceratocystis manginecans and allied species were developed. The threat of exotic pests and diseases of mango is one of the major constraints for the development of expanded trade between the U.S. and foreign markets. One such disease is caused by Ceratocystis manginecans. ARS scientists in Beltsville, Maryland, in collaboration with USDA APHIS scientists also in Beltsville, Maryland, sequenced whole genomes of Ceratocystis manginecans isolates to be used for the development species-specific DNA-based diagnostic assays. This work will be crucial in the identification of infected material and in preventing the entry and spread of this pathogen in the United States and protection of the U.S. mango industry.
3. New species discovered in the fungal genus Coniochaeta. Coniochaeta is a diverse group of fungi that includes many undescribed species, some of which produce chemicals with antimicrobial activity. ARS scientists in Beltsville, Maryland, and the University of Arizona identified three new species of fungi in the genus Coniochaeta isolated from plants and lichens. This work will enhance the ability to identify isolates or species with the potential for antimicrobial activity.
4. Exotic pathogen of the ornamental plant liriope discovered in United States. The ornamental grass liriope (monkey grass or spidergrass) is widely used in landscapes and susceptible to a number of diseases. One disease caused by the fungus Colletotrichum liriope was not known to occur on liriope in the United States, resulting the rejection of imports of this ornamental plant at ports of entry. Diseased material was either destroyed or returned to its original port of departure, resulting in millions of dollars in losses to both importers and exporters. ARS scientists in Beltsville, Maryland, examined numerous samples of diseased liriope collected in the U.S. and discovered that this fungus is relatively widespread. This knowledge will be used by quarantine officials and result in policy changes that save both importers and exporters of liriope millions of dollars each year.
5. The insect biocontrol fungus Beauveria bassiana is a complex of distinct genetic species. The insect biocontrol fungus Beauveria bassiana is used for the control of a wide range of pest insect species of significance to agriculture, horticulture, domestic animals, and humans. Genetic studies indicate that isolates identified as Beauveria bassiana comprise many very similar species that may attack different insects. ARS scientists in Beltsville, Maryland, and Ithaca, New York, in collaboration with researchers at Louisiana State University, tested a new approach for analysis of large numbers of DNA sequences that can distinguish very similar species. This method enables discrimination of previously unrecognized species with probable distinct insect host specificities. This work will be used by pest management professionals to develop new insect biocontrol methods, which will lessen the use of pesticides and result in lower costs and better management for insect control.
Review Publications
Rahnama, M., Szarka, D., Li, H., Dixon, E., Castlebury, L.A., Gauthier, N. 2021. Reemergence of Septoria leaf spot caused by Septoria cannabis on hemp in Kentucky, confirmed by sequence data. Plant Disease. 105:2286-2289. https://doi.org/10.1094/PDIS-12-20-2620-SC.
Herath, I.S., Miriyagalla, S.D., Manamgoda, D.S., Castlebury, L.A., Udayanga, D. 2021. First report of Colletotrichum siamense causing anthracnose-twister disease of onion (Allium cepa) in Sri Lanka. Australasian Plant Disease Notes. 16(30). https://doi.org/10.1007/s13314-021-00444-w.
Davis, W.J., Crouch, J.A. 2021. Analysis of digitized herbarium records and community science observations provides a glimpse of downy mildew diversity of North America and importance of continued digitization and collecting. Fungal Ecology. 55:101126. https://doi.org/10.1016/j.funeco.2021.101126.
Crouch, J.A., Davis, W.J., Shishkoff, N., Castroagudin, V.L., Martin, F.N., Michelmore, R., Thines, M. 2022. Peronosporaceae species causing downy mildew diseases of Poaceae, including nomenclature revisions and diagnostic resources. Fungal Systematics and Evolution. 9(1):43-86. https://doi.org/10.3114/fuse.2022.09.05.
Ferdinandez, H.S., Manamgoda, D.S., Udayanga, D., Deshappriya, N., Munasinghe, M.S., Castlebury, L.A. 2021. Molecular phylogeny and morphology reveal three novel species of Curvularia (Pleosporales, Pleosporaceae) associated with cereal crops and weedy grass hosts. Mycological Progress. 20:431–451. https://doi.org/10.1007/s11557-021-01681-0.
Udayanga, D., Miriyagalla, S.D., Manamgoda, D.S., Lewers, K.S., Gardiennet, A., Castlebury, L.A. 2021. Molecular reassessment of diaporthalean fungi associated with strawberry, including the leaf blight fungus, Paraphomopsis obscurans gen. et comb. nov. (Melanconiellaceae). IMA Fungus. https://doi.org/10.1186/s43008-021-00069-9.
Doherty, J., Crouch, J.A., Roberts, J. 2021. Plant age influences microbiome communities more than plant compartment in greenhouse grown creeping bentgrass. Phytobiomes Journal. 5(4):373-381. https://doi.org/10.1094/PBIOMES-03-21-0021-R.
Davis, W., Crouch, J.A. 2021. The diversification of downy mildew species was not driven by the loss of mycorrhizal associations or the evolution of C4 photosynthesis. Phytofrontiers. 2:60-65. https://doi.org/10.1094/PHYTOFR-04-21-0027-R.
Leblanc, N.R., Martin, F.N., Castroagudin, V.L., Crouch, J. 2021. Mitochondrial loci enable specific quantitative real-time PCR detection of the pathogen causing contemporary impatiens downy mildew epidemics. Plant Disease. 106(1):144-150. https://doi.org/10.1094/PDIS-05-21-0933-RE.
Espevig, T., Sundsdal, K., Aamlid, T.S., Crouch, J.A., Brurberg, M.B., Torp, T., Normann, K., Usoltseva, M., Entwistle, K. 2021. In vitro screening of turfgrass species and cultivars for resistance to dollar spot. International Turfgrass Society Research Journal. https://doi.org/10.1002/its2.78.
Stravoravdis, S., Leblanc, N.R., Marra, R.E., Crouch, J.A., Hulvey, J.P. 2021. Evidence for the role of CYP51A and xenobiotic detoxification in differential sensitivity to azole fungicides in boxwood blight pathogens. International Journal of Molecular Sciences. 22:9255. https://doi.org/10.3390/ijms22179255
Gagkaeva, T.Y., Orina, A.S., Gavrilova, O.P., Usoltseva, M., Crouch, J.A., Normann, K., Entwistle, K., Torp, T., Espevig, T. 2022. In vitro sensitivity of Clarireedia, Fusarium and Microdochium isolated from grasses to commonly used fungicides. International Turfgrass Society Research Journal. 14:972-980. https://doi.org/10.1002/its2.139.
Leadmon, C.E., Sampson, J.K., Maust, M.D., Macias, A.M., Rehner, S.A., Kasson, M.T., Panaccione, D.G. 2020. Several Metarhizium species produce ergot alkaloids in a conditionally specific manner. Applied and Environmental Microbiology. 86(14):1-13. https://doi.org/10.1128/AEM.00373-20.
Salgado-Salazar, C., Romberg, M., Blomquist, C., Nunziata, S., Cai, W., Rivera, Y. 2022. Lifestyle, mating type and mitochondrial genome features of the plant pathogen Calonectria hawksworthii (Hypocreales, Nectriaceae) as revealed by genome analyses. Canadian Journal of Plant Pathology. https://doi.org/10.1080/07060661.2022.2065534.
Crous, P.W., Lombard, L., Sandoval-Denis, M., Seifert, K.A., Schroers, H., Chaverri, P., Gene, J., Salgado-Salazar, C. 2021. Fusarium: more than a node or a foot-shaped basal cell. Studies in Mycology. 98:100116. https://doi.org/10.1016/j.simyco.2021.100116.
Rogers, L.W., Koehler, A.M., Crouch, J.A., Cubeta, M.A., LeBlanc, N.R. 2022. Comparative genomic analysis reveals contraction of gene families with putative roles in pathogenesis in the fungal boxwood pathogens Calonectria henricotiae and C. pseudonaviculata. BMC Ecology and Evolution. 22:29. https://doi.org/10.1186/s12862-022-02035-4.