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Metabolic Studies and Bioengineering of Plant Trichomes Towards Enhancing Pest/Disease Resistance and Facilitating Molecular Farming
G. J. Wagner
Department of Plant and Soil Sciences
The work described in this project is directly related to world-wide efforts towards "molecular farming" to exploit plants for sustainable production of non-traditional, commercially-valuable products, i.e., non-food or fiber products. The success in these efforts will depend on acquiring a better fundamental understanding of the metabolism and metabolic regulation underlying plant surface secretion processes, coupled with direct efforts to apply available tools to manipulate these systems towards a useful purpose.
Our work is focused on exploitation of plant trichomes to enhance natural-product-based pest/disease resistance and develop possibilities for molecular farming of trichome secretions that might be used to protect other plants (e.g., food crops, ornamentals) against damage from pests and disease, or as commercial chemical feed-stocks.
A new and recent focus stems from our discovery of antifungal proteins we have called "phylloplanins" that are also produced on aerial surfaces of certain plants. There is a growing need for novel fungicides, particularly natural product based compounds, to augment and replace currently used, chemically-synthesized products whose marketability is under challenge because of environmental concerns.
2009 Project Description
In this period we have extended studies of phylloplanins to show that T-phylloplanin inhibits at least 1 member of all four major classes of fungi/fungi-like organisms (ascomycete, basidiomycete, zygomycete, oomycete). Further study shows that recombinant a T-phylloplanin fusion protein is also effective against several different fungal species. Field trials in 2009 showed the efficacy of T-phylloplanin against gray leaf spot and brown patch diseases on turf grasses in the field, and concentration dependence was observed.
Studies to determine the mechanism of action of T-phylloplanin against P. tabacina spores and on-plant disease, and against P. oryzae hyphae indicate that the protein causes ion leakage. This has been quantitatively shown. T-phylloplanin is also shown to cause ion K and proton leakage from isolated tonoplast vesicles isolated from tobacco roots (model membrane).
Transformation of a P. tabacina sensitive tobacco with T-phylloplanin resulted in endogenous resistance to this pathogen. Collaborative work is underway to test the usefulness of T-phylloplanin for treating a specific fungal disease of honey bees and its possible usefulness for treating white nose syndrome in bats.
Our results further support the potential of phylloplanins for use as natural product fungicides. Our current focus is on turf grass diseases and tobacco. Results of field studies in 2009 and other work indicate that phylloplanin-containing preparations can find usefulness in treating golf courses, athletic fields, residential and business lawns, etc as well as sod farms to control diseases and reduce the reliance on chemically synthesized fungicides in such applications. Collaborative studies that were initiated during 2009, if fruitful, could extend the usefulness of natural-product phylloplanins for treating fungal diseases of beneficial insects and animals. Portions of this work have been resubmitted for publication and other portions are in preparation for submission.
Kroumova, A.M., Wagner, G.J. (2010) Pathways for synthesis, and possibilities for genetic modification of sugar ester acyl groups produced by trichomes of Solanaceous species. General and Applied Plant Physiology. (in press).
King, B., Williams, D., Wagner, G.J. (2010) T-phylloplanins inhibit gray leaf spot and brown patch diseases on turf grasses. Crop Physiology (submitted).