Location: Crop Bioprotection Research
2017 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.
Progress Report
This is the first progress report for project 5010-22410-019-00D which was initiated on May 9, 2017. Research has begun in meeting the five-year project objectives which are to 1) Develop new microbial culturing and mass production technologies for biocontrol agents and nutritionally fastidious plant pathogens and 2) Define interactions between biocontrol agents, hosts, and pathogens using traditional and genomic approaches to increase disease management success. In research focused on the first project objective, ARS in Peoria, Illinois, initiated studies to isolate osmotolerant variants of yeast biocontrol agent Cryptococcus flavescens strain 3C which is active against the wheat disease Fusarium head blight (FHB). Protocols to be used in subsequent experimentation were also developed. In collaboration with scientists at a university, ARS scientists conducted field tests in Peoria, Illinois and Wooster, Ohio that employed strain 3C in combination or not with fungicides and a new ARS-discovered, starch-based antimicrobial compound. A small pilot study to evaluate new measures for reducing Pythium leak on stored potato tubers was conducted with researchers at the university using Gram negative bacterial biocontrol agents that were dried by ARS scientists in different carriers and then applied to tubers in combination or not with chemical control products.
Studies also were initiated on nutritionally fastidious plant pathogens and included work to produce callus tissue of basil and then to infect callus with Peronospora belbahrii, an economically important causal agent of downy mildew of basil. Establishing such two component systems would greatly facilitate conducting genomic, proteomic and metabolomic studies on this otherwise non-culturable pathogen. Studies are also progressing to determine the effect of a wide variety of fungicides against the pathogen on basil and understand how combining the best fungicides identified with biocontrol agents would influence overall control of the disease. Experiments have also been initiated on Sclerophthora macrospora, a nutritionally fastidious plant pathogen that incites crazy top on corn and yellow tuft disease in turf.
In work conducted under Objective 2, ARS scientists in Peoria, Illinois have begun work utilizing quantitative polymerase chain reaction (PCR) to characterize microbial population genomics over time when potato wounds are inoculated with co-cultured biocontrol agents in the presence or absence of a pathogen. Ribonucleic acid (RNA) sequencing is also being employed to characterize the type and quantity of RNA at various time points in liquid cultures of yeast biocontrol agent 3C after cold shocking cultures. This research is expected to provide basic and applied knowledge relating to improving the production and commercial development potential of biocontrol products by ARS partner industries.
Accomplishments
