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Plant Metabolic
Engineering Under Construction: Design Rules and Tools Needed
Jacqueline V. Shanks
Iowa State University
Objective:
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To engineer C. roseus hairy roots for
the overproduction of tryptophan and indole alkaloids |
Approach:
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Develop an inducible promoter system in Catharanthus
roseus hairy root cultures |
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Construct and characterize transgenic hairy root lines
overexpressing key enzymes in the indole and non-mevalonate terpenoid
pathways |
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Develop methods for NMR-based metabolic flux maps |
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Perform metabolic characterization of these first
generation transgenic lines |
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Develop techniques for co-transformation that allow the
introduction of multiple genes |
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Construct and characterize a second generation of
transgenic lines expressing strategic combinations of genes as
determined from the results of the first generation transgenic lines |
Accomplishments:
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Glucocorticoid-mediated inducible promoter system
developed in Catharanthus roseus hairy root cultures |
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Development of the bondomer concept and software in
analysis of NMR carbon-bond labeling experiments |
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Demonstration of an NMR flux map for central and
intermediary carbon metabolism in a three compartment model (cytoplasm,
mitochondrion, and plastid) in plant tissues |
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NMR flux map tool extended to crop plants (soybean) |
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Huge overproduction of tryptophan (>300-fold) and
tryptamine (>10-fold) in engineered hairy root lines and small
increases in indole alkaloid production |
Impact:
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Enhance the nutritional
value of crops for human and animal consumption |
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Enhance the
overproduction of medicinal metabolites in crops |
Abstract:
Plants
are the raw materials for the world’s feed supply as well as biobased
industrial products. Providing an ample
food supply for all humankind is a serious challenge for our society. Plants as a biorenewable resource have the
potential for providing society with many of our basic goods as well as
energy. The design of plants to meet these potentially competing
demands is a scientific and engineering challenge. Plant metabolic
engineering provides a means of understanding plant biology - “systems
biology”. Plant metabolic engineering is also the basis of designing
new plants. “Predictive metabolic engineering” (Sweetlove, Last, and
Fernie, 2003) is a worthy goal for both aspects. The
integration of knowledge for prediction will require design software as
well as powerful experimental tools. While comprehensive integration of
“omics” data in a mathematical model is an ideal goal, using these
types of techniques on subsets of metabolism could help develop
logic-based design rules, instead of empirical ones. Plants, by both
their complexity and timescale of growth, impose formidable
requirements for quantitative analysis and precise synthesis tools. This talk will highlight some of our work in
engineering of overproduction of tryptophan and indole alkaloids in
hairy root cultures of the medicinal plant Catharanthus
roseus.
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