Browsing by Subject "Department of Plant Pathology"

Now showing 1 - 4 of 4
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    Analysis of Natural Antimicrobial Extracts of Rhus typhina Found in Minneapolis
    (2012-04-18) Barbeau, Adam
    Plants produce numerous organic compounds that have antimicrobial activity. (Borchardt, 2008b; Gillitzer et al. in review) These natural products are found in tissues and structures throughout the plant, including the stems, berries, mature/young leaves, and roots. The many native and naturalized plant species that grow throughout Minnesota are a potential source of chemicals with antimicrobial properties that could be useful in medicines, cosmetics, preservatives or pesticides. Identification of antimicrobial compounds from a wide array of plant tissues and numerous plant species requires screening of numerous extracts from many different plant sources for their biological activity. Alamar Blue (AB), a nontoxic, water soluble dye, changes color from indigo blue to fluorescent pink in the presence of living cells. This color change is an accurate indicator of the fungistatic activity of plant extracts, via respiration, dissolved in a solution of water, nutrient broth, and AB. Phytopthora sojae is a soil borne plant pathogen and major cause of soybean crop loss. Zoospores are a motile reproductive stage of P. sojae critical to the infection process.
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    Bark Beetle: Fungus Interactions in Declining Hickory Trees
    (2010-11-29) Zenner, Bobbi
    The objective of this study is to determine whether C. smalleyi is commonly carried by hickory bark beetles when they emerge from beetle infested, declining bitternut hickory in late spring. The findings will help answer the question of whether the beetle is an important vector of C. smalleyi. These results will be added to those of additional assays of beetles from the same site as well as from a second Wisconsin location.
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    Designing a Screening Method for Organic Seed Treatments
    (2009-04-08) Lis, Dmitriy
    Certified organic crop producers have limited options available for controlling seed related diseases. I have developed a screen that could be utilized to test various plant extracts as a possible seed treatment. In the initial screen, I tested paper birch (Betula papyrifer) and staghorn sumac (Rhus typhina) extracts against 4 plant pathogens: Fusarium solani, Phytophthora sojae, Rhizoctonia solani, and Pythium spp. The highest concentration of the sumac extract (25.0 micrograms/ml) reduced the growth of R. solani by 67%, F. solani and Pythium spp. by 100%, and P. sojae by 80%. The highest concentration of the sumac extract (25.0 micrograms/ml) reduced the growth of F. solani and Pythium spp. equal to or greater than the commercial seed treatment fungicides. The highest concentration of the paper birch extract (25.0 micrograms/ml) reduced the growth of R. solani by 47%, Pythium spp. by 40%, and P. sojae by 40%. Neither the sumac or the paper birch extract reduced the germination of soybean seeds.
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    Plant Signaling Compounds Alter Secondary Metabolite Production Among Antagonistic Streptomyces
    (2009-10-07) Bakker, Matthew; Salomon, Christine; Kinkel, Linda
    Streptomycetes have been implicated in the control of soil-borne plant pathogens, and are known to produce an extensive array of antimicrobial secondary metabolites. We investigated the hypothesis that plants manipulate the production of secondary metabolites by streptomycetes. We tested a collection of diverse Streptomyces isolates for responses to potential signaling molecules produced by plants, including plant hormones, flavonoids, sesquiterpene lactones, and crude root exudates. Secondary metabolite production was investigated with the use of high performance liquid chromatography (HPLC) and bioassays for inhibitory activity. We found evidence that streptomycetes respond to plant-produced compounds with altered patterns of secondary metabolite production. Streptomyces isolates in our study had the ability to chemically modify and produce close analogs of plant-derived compounds. The production of similar chemical compounds may facilitate cross-kingdom communication. Our work suggests the potential for plants to manipulate the activities of soil microbial communities, which may confer a selective advantage in suppression of plant pathogens. These results concur with studies from many different systems showing that microbial activity is tightly linked with the health and functioning of higher organisms.