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Pioneering
mass spectrometry methods developed at the U.S. Department of Energy’s (DOE’s)
Ames Laboratory are helping plant biologists get their first glimpses of
never-before-seen plant tissue structures.
The
new method opens up new realms of study, ones that might have long-ranging
implications for biofuels research and crop genetics.
“The
data we’re seeing are unprecedented,” says Basil Nikolau, the Ames Laboratory
faculty scientist heading up the project, funded by DOE’s Office of Science.
The
laboratory’s team of researchers has developed a new more highly sensitive mass
spectrometry technique to investigate metabolites, the small molecules that are
the building blocks for plant biological processes.
Young-Jin Lee, a faculty
scientist in Ames Laboratory’s Chemical and Biological Sciences Division, has
successfully demonstrated the use of matrix-assisted laser
desorption/ionization-mass spectrometry, or MALDI-MS, to map the lipids in
cottonseed in a paper published in The
Plant Cell.
The research group’s
technique is also featured in a paper published in The Plant Journal, highlighting new developments in high-resolution
measurements in plant biology. The imaging technique can make maps of the
locations of molecules in plant materials with resolution of 10 to 50 microns,
less than a quarter the size of a human hair.
MALDI-MS has been in use in
the medical and pharmaceutical fields for about the last decade, Lee says.
“In the medical field
researchers were using this type of spectrometry to map proteins in human
cancers and visualize the distribution of drugs through tissues. But in recent
years the scientific community began to look at MALDI-MS as a possibility for
mapping metabolites in plant material,” says Lee.
Traditional methods in gas
chromatography and mass spectrometry told plant biologists the “what and how
much” of plant metabolites, but not the “where.”
“Before these advances, in
order to analyze plant material, biologists were forced to crush up tissue. We
would lose spatial information, where these metabolites were located in
different types of plant cells,” says Nikolau.
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“The
traditional methods provided qualitative and quantitative analysis, but it lost
all localization of these small molecules,” says Lee. “With this technique we
can see the distribution of these metabolites in the plant tissue at the single
cell level.”
In
Lee’s study of cottonseeds, done in partnership with a team of U.S. and German
scientists, the technique showed a distribution of lipids that varies with
tissue function. The knowledge could yield useful information about cottonseed,
a crop valued as a possible source of biofuel and for its oil in the food
industry.
“This
information is really so new to scientists that we don’t know yet what it
means. As a matter of fact, it challenges plant biologists at the moment
to take hold of that data and integrate it into the way they do their science,”
says Nikolau. “This data will change the future of how we do research.”
Lee
said that though there was still much to learn about developing procedures
using MALDI-MS to detect the tiny amounts of material in cells, he expects the
use of the technique in plant science to gain wider use.
“Up
until this point, this method has not really been recognized by plant
scientists. But we were able to bring the technologies of analytical chemistry
to the biological science problem of being able to map molecules at the single
cell level. There is still a lot to learn about the process, but this
technique is going to blossom very rapidly in the next few years.”
Nikolau
believes the technology will be a key to thoroughly understanding plant
biosynthesis, and in turn alternative energy production.
“This
is really about the sustainability of our chemical world,” he says. “When
you’re talking about chemical energy, you’re talking about carbon. Historically,
over the last 100 years, it’s been carbon from petroleum. If you’re going to
make biorenewable chemicals, the carbon comes in through photosynthesis,
through plants. That process happens in discrete compartments within the
organism, within individual cells. Science needs to know that highly detailed
spatial information to take full advantage of it.”
Source: Ames Laboratory
