 |
|
Current Research
Modification of Fatty Acid Composition:
|
To increase the value of soybean oil, we identify genes
for novel fatty acid modifying enzymes from non-agronomic
plant species. These genes can then be transgenically
expressed in soybean seeds to produce oils with enhanced
properties, particularly for industrial applications. We have
identified a number of "new"
enzymes. These include
enzymes that are referred to as "fatty acid conjugases,"
which generate conjugated double bonds in fatty acid
substrates. Fatty acid conjugase genes that we have
isolated from plants such as
Momordica charantia
and
Calendula officinalis
have been expressed in soybean
seeds to produce oils with improved properties as drying
agents in paints, inks, and varnishes. More recently, we
have identified a divergent cytochrome P450 from
Euphorbia lagascae
that introduces epoxy groups in fatty acids. Expression of this enzyme in soybean seeds
resulted in the production of epoxidized oils that can be used in plasticizers, adhesives,
and paints.
|
Oil comprises nearly 20 percent of the
weight of soybean seeds. The fatty acid composition of the oil can
be genetically modified to enhance the nutritional, animal feed, and
industrial uses of the seed. |
Current research is directed towards identifying
biochemical factors that limit the accumulation and
proper metabolism of novel fatty acids in transgenic
soybeans. Knowledge gained from this research will
be used to engineer high levels of novel fatty acids in soybean oil
In addition, growth temperature has been
shown to have a profound effect on the fatty acid composition of
certain economically valuable oil traits in soybean. We are also
examining the biochemical and genetic basis for this phenomenon.
|
Calendula
officinalis (Pot marigold). Fatty acid conjugase genes isolated
from pot marigold have been used to produce soybeans with improved
properties for paint, ink, and other coatings applications.
|
|
Vitamin E Biofortification:
We have recently discovered
the gene for homogentisic acid geranylgeranyl transferase (HGGT).
This enzyme catalyzes the committed step in the synthesis of the
tocotrienol form of Vitamin E in cereal grains. The HGGT gene has
proven useful for generating large enhancements in the content of
Vitamin E antioxidants in a variety of plant tissues. For example,
we have succeeded in generating corn seeds with four- to six-fold
higher levels of Vitamin E antioxidants by transgenic expression of
the HGGT gene. By using a similar approach, we have also engineered
a 10- to 15-fold increase in Vitamin E antioxidants in Arabidopsis
leaves.
One component of our current
research is to characterize the biochemical properties of the HGGT
enzyme. We are also attempting to generate further
enhancements in Vitamin E content by engineering increased metabolic
flux through rate-limiting steps in this pathway. It is
anticipated that this research will lead to crops with improved
nutritional properties for humans and livestock. In addition,
Vitamin E is a potent lipid-soluble antioxidant. Based on this
property, increased amounts of Vitamin E should enhance the shelf
life of plant products and improve the ability of plants to resist
oxidative stresses.
|
|
|
|
Sphingolipid Biosynthesis and Function:
My lab is a
participant in a collaborative research project aimed at
characterizing the biosynthesis and function of sphingolipids in
Arabidopsis. This project is funded by the National Science
Foundation Arabidopsis 2010 program. Other members of the
collaborative team are Jan Jaworski, Donald Danforth Plant Science
Center, Teresa Dunn, Uniformed Services University of the Health
Sciences (Project Director), Daniel Lynch, Williams College, and
Johnathan Napier, Rothamsted Research.
Sphingolipids are major
components of the plasma membrane and tonoplast of plant cells.
These molecules have been linked with programmed cell death in
plants, and the biosynthetic pathway of sphingolipids is a target
for agriculturally important mycotoxins such as fumonisins and AAL
toxin. Our current research includes the identification of
Arabidopsis mutants that are defective in various steps in
sphingolipid synthesis. These mutants will be used as tools to more
precisely elucidate the function of sphingolipids in plants.
Project web page:
http://www.plantsphingolipids.org |
|
|
|
|
|