Location: Crop Bioprotection Research
2022 Annual Report
Objectives
Objective 1: Develop new microbial culturing and mass production technologies for biocontrol agents and nutritionally fastidious plant pathogens.
Subobjective 1a: Develop new microbial culturing technologies for biocontrol agents.
Subojective 1b: Develop new methodologies for culturing nutritionally fastidious plant pathogens.
Objective 2: Define interactions between biocontrol agents, hosts, and pathogens using traditional and genomic approaches to increase disease management success.
Approach
Our approach will be to apply technologies allied with the fields of fermentation science, microbial physiology, metabolomics, genomics, and proteomics for two purposes: to enhance the efficacy and shelf-life of the antagonist biomass manufactured and to produce gnotobiotic (i.e., all of a limited number of organisms in a culture are known) or axenic cultures of nutritionally fastidious plant pathogens. More specifically, the shelf-life and efficacy of biocontrol strains will be improved by isolating efficacious stress tolerant variants of a yeast biocontrol agent and then testing the more promising strains isolated in small pilot tests against Fusarium head blight of wheat. Other studies will strive to discover cell production methodologies that promote the production of compounds that enhance cell stress tolerance. Strain transcriptional response to culture conditions will be determined to facilitate optimizing these cell production studies. This will include studies to elucidate the transcriptional response of a yeast biocontrol strain to cold-adaptation that improves cell survival and biocontrol efficacy. Gnotobiotic culturing studies will include establishing a selection of host plants in sterile tissue culture boxes or as callus cell cultures and evaluating methods for infecting these host tissues with axenic propagules of an obligate pathogen. The transcriptional response of gnotobiotic host cell tissue to infection by an obligate plant pathogen will then be determined as a prelude to attempting to grow one or more obligate plant pathogens in axenic culture.
Accomplishments
1. Identified genes that participate during the infection process of downy mildew. Downy mildew infects susceptible basil cultivars every year in the United States and can cause significant losses in yield and crop quality. The pathogen responsible for downy mildew disease on basil has not been well studied at the molecular level, primarily because the pathogen will not grow on artificial growth medium, but only on living plants. The ability to grow it outside the plant will expedite research on this important pathogen. ARS researchers in Peoria, Illinois, collaborated with scientists from the Agricultural Research Organization of Israel and the University of Hawaii to identify the genes in basil plants that are turned on during course of the disease. We also identified the genes the pathogen uses during the infection process. Knowledge of the nutrients the pathogen is utilizing will enable us to better develop methods to cultivate it outside the plant. These results contribute important knowledge of the infection process of basil downy mildew and could aid the development of more effective measures for reducing the severity of the disease.
Review Publications
Soni, R., Keharia, H., Dunlap, C.A., Pandit, N., Doshi, J. 2022. Functional annotation unravels probiotic properties of a poultry isolate, Bacillus velezensis CGS1.1. LWT - Food Science and Technology. 153. Article 112471. https://doi.org/10.1016/j.lwt.2021.112471.
Dowd, P.F., Naumann, T.A., Johnson, E.T. 2022. A maize gene coding for a chimeric superlectin reduces growth of maize fungal pathogens and insect pests when expressed transgenically in maize callus. Plant Gene. 30. Article 100359. https://doi.org/10.1016/j.plgene.2022.100359.
Ma, W., Johnson, E.T. 2021. Natural flavour (E,E)-2,4-heptadienal as a potential fumigant for control of Aspergillus flavus in stored peanut seeds: finding new antifungal agents based on preservative sorbic acid. Food Control. 124. Article 107938. https://doi.org/10.1016/j.foodcont.2021.107938.
Dowd, P.F., Johnson, E.T. 2022. Different maize (Zea mays L.) inbreds influence the efficacy of Beaveria bassiana against major maize caterpillar pests, which is potentially affected by maize pathogen resistance. Biocontrol Science and Technology. 32(7):847-862. https://doi.org/10.1080/09583157.2022.2055745.
