Location: Cereal Disease Lab2021 Annual Report
Objective 1: Discover specific factors involved in pathogenicity, sporulation and toxin synthesis for the FHB pathogen and related fungi by applying genomic and functional approaches. Sub-objective 1.A. Functionally characterize cellular processes and structures that determine plant pathogenesis. Sub-objective 1.B. Identify genes uniquely or differentially expressed during development that defines pathogen structure and function. Objective 2: Relate fungal genotypes to mycotoxin production in fungal strains in field production environments to aid in developing enhanced methods of control. Sub-objective 2.A. Monitor genetic changes in critical pathogen populations by pathogen surveys. Sub-objective 2.B. Characterize populations of Fusarium from native North American grasses that may be sources of novel pathogen genotypes and/or host resistance. Objective 3: Optimize metagenomic and functional approaches to define the phytobiome of healthy and diseased plants naturally infested with the FHB fungus. Sub-objective 3.A. Characterize phytobiome and soil carbon composition. Sub-objective 3.B. Determine the relative abundance of competitive phenotypes and impacts on plant productivity. Objective 4: Identify novel sources of plant disease resistance to FHB and mycotoxins produced by FHB fungi to improve breeding for resistance. Sub-objective 4.A. Characterize the epigenetic changes of FHB resistant durum cultivars produced by altering the DNA methylation pattern. Sub-objective 4.B. Characterize durum lines missing a portion of chromosome 2A region that may contain the FHB suppressor locus. Objective 5: Introgress new genes of scab resistance into barley and wheat germplasm.
Improved management strategies are needed to maintain adequate plant disease control. Specific approaches include: 1) Genetic information obtained from the fungal pathogen, Fusarium, will be used to identify genes factors responsible for fungal pathogenesis, possibly leading to novel approaches to control FHB disease and reduce toxin levels in grain; 2) FHB levels, strain diversity, and the nature of associated fungal communities, will be monitored by population genetic and metagenomic approaches improving the ability to forecast the economic impact and the design of effective management strategies; 3) Novel sources of FHB resistance and mycotoxin tolerance will be developed for plants.
In the fourth full year of the project, ARS scientists located at Saint Paul, Minnesota, had made considerably less progress than initially projected due to the Covid-19 travel and lab restrictions: Sub-objective 1.A.1. Protein samples were prepared from toxisomes. Sub-objective 1.A.2. Gene constructs for creating mutants and misdirecting proteins were prepared and are available. Sub-objective 1.B. Mutants were created but phenotyping did not occur. Objective 2. The annual FHB surveys and survey comparisons were canceled in 2020. Objective 3. Electronic display of past culture collection data was posted online as part of a collaborative project. Sub-objective 4.A. To narrow the list of candidate genes additional mutants and samples were characterized for their gene expression patterns. This resulted in a list of 25 candidate genes that are in common between the samples. We are now confirming this finding by quantitative PCR amplification at various time points and additional lines. Sub-objective 4.B. Phenotypic characterization of deletion lines. Populations are being further phenotyped to confirm the initial results and assure resistance is true and not escapes.
1. New lines of durum wheat reveal a list of 25 new potential targets for disease resistance. Fusarium head blight disease of durum wheat is a significant constraint to the profitable production of this crop. Genetic sources of resistance to the disease are limited. ARS researchers located at Saint Paul, Minnesota, identified a total of 25 genes with significantly altered expression patterns when the plant was exposed to Fusarium head blight that could play a critical role in the mechanisms by which wheat resists the deleterious impacts of disease. It is possible that a single or multiple genes among these 25, based on gene network analysis, are acting to enhance disease resistance in these lines. New sources of resistance would benefit farmers by increasing the quality of grain produced and reducing production costs by reducing fungicide applications used to control disease.
Wang, B., Yu, H., Jia, Y., Dong, Q., Steinberg, C., Alabouvette, C., Edel-Hermann, V., Kistler, H.C., Ye, K., Ma, L., Guo, L. 2020. Chromosome-scale genome assembly of Fusarium oxysporum strain Fo47, a fungal endophyte and biocontrol agent. Molecular Plant-Microbe Interactions. 33(9):1108-1111. https://doi.org/10.1094/MPMI-05-20-0116-A.
O'Donnell, K., Al-Hatmi, A.M.S., Aoki, T., Brankovics, B., Cano-Lira, J.F., Coleman, J.J., de Hoog, G.S., Di Pietro, A., Frandsen, R.J., Geiser, D.M., Gibas, C.F., Kim, H.-S., Kistler, H.C., Laraba, I., Proctor, R.H., Ward, T.J., et al. 2020. No to Neocosmospora: Phylogenomic and practical reasons for continued inclusion of the Fusarium solani species complex in the genus Fusarium. mSphere. 5(5). Article e00810-20. https://doi.org/10.1128/mSphere.00810-20.
Guo, L., Yu, H., Wang, B., Vescio, K., Deiulio, G.A., Yang, H., Berg, A., Zhang, L., Steinberg, C., Edel-Hermann, V., Kistler, H.C., Ma, L. 2021. Metatranscriptomic comparison of endophytic and pathogenic Fusarium–Arabidopsis interactions reveals plant transcriptional plasticity. Biology of Plant Microbe Interactions. https://doi.org/10.1094/MPMI-03-21-0063-R.