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United States Department of Agriculture

Agricultural Research Service

Research Project: SYSTEMATIC BIOLOGY OF INVASIVE AND EMERGING PLANT PATHOGENIC FUNGI
2011 Annual Report


1a.Objectives (from AD-416)
Characterize and analyze phylogenetic relationships for important disease-causing basidiomycetes with emphasis on smut and bunt fungi on cultivated grains and turf grasses, and rust fungi as pathogens of crops. Characterize and analyze phylogenetic relationships of ascomycetous pathogens based on morphological and molecular characteristics with emphasis on canker and related anthracnose fungi causing diseases of tree fruit crops and forest trees.


1b.Approach (from AD-416)
Smut and bunt fungi associated with turf grasses, cultivated grains, and weedy plants in the genera Tilletia, Ustilago, and Urocystis will be collected, cultured and characterized with morphological and molecular data. A wide range of rusts on weedy and crop plant hosts will be collected and characterized with DNA sequence data in order to determine both higher-level relationships and species relationships. Taxon-specific PCR primers will be developed for genes of interest when necessary. For both rusts and smuts PCR will be performed to amplify ribosomal and protein-coding genes, including ITS, LSU, SSU, EF1-alpha, and RNA polymerase gene regions. Species concepts will be defined based on multi-gene phylogenetic trees and morphological data when possible. Fungal pathogens of tropical hosts will be characterized with molecular data and ribosomal gene regions will be used to determine their relationships. Sequence data will be used to develop rapid methods for identification and correlated with morphological data when available. Diaporthalean taxa, including Diaporthe-Phomopsis and Valsa-Cytospora and taxa in the Nectria family of the Hypocreales will be collected and characterized morphologically. PCR will be performed to amplify ribosomal and protein-coding genes, including ITS, LSU, SSU, EF1-alpha, and RNA polymerase gene regions. Species concepts will be defined based on multi-gene phylogenetic trees in combination with morphological data. As new pathogens in these groups emerge, species previously unknown to science yet related to known pathogens in these groups will be described, illustrated and characterized. Taxonomic monographs will be published and made available as online resources.


3.Progress Report
Research on canker causing fungi in the Diaporthales has resulted in monographic accounts of several important genera with a number of newly discovered species. Three genera have been monographed based on the results of multigene phylogenies combined with complete descriptions and illustrations. This research confirms the relationships of these fungi with specific host genera and species. In some cases species were determined to occur only on one continent rather than being widely distributed. These more accurate species definitions have implications for international trade.

Fungi in the Hypocreales were studied that causes canker diseases of hardwood trees including beech bark canker as well as root and rhizome rots. Relationships among the species in this group of fungi are not well known. Using a multigene phylogeny and an examination of microscopic characteristics, species in these groups were accurately defined. Research was completed on Nectria that resulted in a monographic account of this genus. As a result three genera are recognized with 56 species many of which are new to science. Species were determined to correlate closely with plant host, often with limited distribution. Within the genus Neonectria that includes the beech bark canker fungus, it was determined that these species represent four different groups or genera that differ biologically. The fungi that cause diseases on hardwood trees in temperate regions are distinct from those in the tropics that live on dead woody tissues. These are also different from the fungi that cause root and rhizome rots. Each group including three genera new to science is described and illustrated. A key to the four genera is provided. This research will be used by plant diagnosticians and forest pathologists who need to identify the fungi that cause these diseases.


4.Accomplishments
1. DNA diagnostic protocols were developed for accurate identification of rust fungi causing turfgrass diseases. The diseases of turfgrass on golf courses and lawns causes millions of dollars damage each year. These diseases are increasingly caused by fungi including three similar-looking rust fungi. Knowing exactly which rust fungi are present is essential for treating the diseases. In this research samples of turfgrass were tested for the presence of rust fungi using DNA sequences. Three different rust fungi were found to be associated with different cultivars of Kentucky bluegrass. For the first time a rapid DNA-based diagnostic test was developed to accurately identify each rust species. This research will be used by plant pathologists to determine the cause and thus provide effective treatment of these turfgrass diseases.

2. A major monograph of canker-causing fungi was completed. Fungi are a group of organisms that cause billions of dollars damage each year to agricultural and forest resources in the United States. One group of fungi includes fungal species that cause canker diseases on woody plants such as cherry and apple trees. In this research hundreds of specimens and living cultures of three genera of canker-causing fungi from around the world were examined to determine both their macroscopic and microscopic appearance. In addition DNA sequence data were analyzed to evaluate the limits and relationships among the species. Of the 56 species included, thirteen species are new to science. All species of these three genera are described and illustrated with a key provided for their identification. This research will be used by plant pathologists and plant quarantine officials to identify the fungi that cause diseases on woody plants.

3. A fungus was identified that controls Brazilian peppertree in Florida. Invasive weeds destroy delicate ecosystems especially in the Florida Everglades National Park. Recently Brazilian peppertree has invaded more than 4,000 acres within the Park. A fungus was discovered that kills the seeds and seedlings of this tree and thus may prove useful in controlling this weed. In addition, the host range of this fungus on related host species was determined. This research will be used by ecologists and plant pathologists working to control this noxious weed tree.


Review Publications
Chaverri, P., Salgado, C., Hirooka, Y., Rossman, A.Y., Samuels, G.J. 2011. Delimitation of Neonectria and Cylindrocarpon (Nectriaceae, Hypocreales, Ascomycota) and related genera with Cylindrocarpon-like anamorphs. Studies in Mycology. 68:57-78.

Hirooka, Y., Rossman, A.Y., Chaverri, P. 2011. Morphological and phylogenetic analyses of the Nectria cinnabarina species complex. Studies in Mycology. 68:35-56.

Mejia, L., Rossman, A.Y., Castlebury, L.A., White, J. 2011. New species, phylogeny, host-associations, and geographic distribution of the genus Cryptosporella (Gnomoniaceae, Diaporthales). Mycologia. 103:379-399.

Mejia, L., Rossman, A.Y., Castlebury, L.A., White, J. 2011. A systematic account of the genus Plagiostoma (Gnomoniaceae, Diaporthales) based on morphology, host-associations, and a four gene phylogeny. Studies in Mycology. 68:211-235.

Walker, D., Castlebury, L.A., Rossman, A.Y., Sogonov, M., White, J. 2010. Systematics of the genus Gnomoniopsis (Gnomoniaceae, Diaporthales) based on a three gene phylogeny, host associations, and morphology. Mycologia. 102:1479-1496.

Yun, H., Hong, S., Rossman, A.Y., Lee, S., Lee, K., Bae, K. 2009. The rust fungus Gymnosporangium in Korea including two new species, G. monticola and G. unicorne. Mycologia. 101(6):790-809.

Gregory, N., Bischoff, J., Dixon, L.J., Ciurlino, R. 2010. First report of the Telial stage of Japanese apple rust on Juniperus chinensis in North America and confirmation of the Aecial stage on Malus domestica. Plant Disease. 94:1169.

Dervis, S., Dixon, L.J., Doganlar, M., Rossman, A.Y. 2010. Gall production on hawthorns caused by Gymnosporangium spp.in Hatay province, Turkey. Phytoparasitica. 38:391-400.

Minnis, A., Rossman, A.Y., Farr, D., Olsen, R.T. 2010. Sphaerographium nyssicola Minnis, Rossman & D.F. Farr, sp. nov. Persoonia: Molecular Phylogeny and Evolution of Fungi. 25:122-123.

Shetty, K., Minnis, A., Rossman, A.Y., Jayachandran, K. 2010. Brazilian peppertree seed-borne pathogen, Neofusicoccum batangarum, a potential biocontrol agent. Biocontrol. 56:91-97.

Yun, H., Rossman, A.Y. 2011. Tubakia seoraksanensis sp. nov., a new species from Korea. Mycotaxon. 115:369-373.

Miller, J., Rossman, A.Y., Rosentreter, R., Ponzetti, J. 2011. Lichen ecology and diversity of a sagebrush steppe in Oregon: 1977 to the present. North American Fungi. 6(2):1-14.

Saumtally, S.A., Viremouneix, T.R., Ahondokpê, B., Girard, J.R., Castlebury, L.A., Dixon, L., Glynn, N.C., and Comstock, J.C. First Report of Orange Rust of Sugarcane Caused by Puccinia kuehnii in Ivory Coast and Cameroon. Plant Dis. 95:357. 2011.

Minnis, A., Rossman, A.Y., Olsen, R.T. 2011. Mycosphaerella nyssicola revisited: characterization of a species distinct from M. punctiformis. Mycotaxon. 155:311-322.

Ramirez-Mendoza, M.R., Rebollar-Alviter, A., Minnis, A.M., Dixon, L.J., Castlebury, L.A., Valdovinos-Ponce, G., Silva-Rojas, H.V. 2011. First report of leaf rust of blueberry caused by Thekopsora minima in Mexico. Plant Disease. 95:772.

Henk, D.A., Farr, D.F., Aime, M.C. 2011. Mycodiplosis infestation of rust fungi is frequent, wide spread, and possibly host specific. Fungal Ecology. 4:284-289.

Schilder, M., Lizotte, E., Yun, H., Dixon, L., Castlebury, L.A. 2011. First report of Juneberry rust caused by Gymnosporangium nelsonii on Juneberry in Michigan. Plant Disease. 95(6):770.

Last Modified: 10/20/2014
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