By Ben
Coxworth
October 17, 2022
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A close look at the engineered Lemna japonica duckweed, the
oil yield of which is reportedly seven times higher than that of soybeans Photo:
Brookhaven National Laboratory
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The study was conducted by researchers from the US
Department of Energy’s Brookhaven National Laboratory and New York's Cold
Spring Harbor Laboratory. They started with an existing type of duckweed known
as Lemna japonica, to which they added multiple genes which were already
known to drive oil production and storage in other plants.
In what is described as a push/pull/protect effect, one of
those genes pushes (increases) the production of fatty acids, one of them pulls
(assembles) those fatty acids into triacylglycerol oils, and another protects
them from environmental degradation by coating the oil droplets in plant
tissue. As a result, the engineered duckweed accumulates oil at almost 10% of
its dry weight biomass, which is reportedly a 100-fold increase over the
accumulation rate of the plant's wild counterpart.
Its oil yields are also seven times higher than those of
soybeans. Unlike soybeans, however, crops of the duckweed wouldn't take up
farmland, as they'd be grown in large vessels or ponds. In fact, the scientists
suggest that duckweed crops could be grown in the liquid waste runoff from pig
and poultry farms, which the plants would help to clean up by drawing excess
nutrients out of the water.
Brookhaven Lab postdoctoral researcher Yuanxue Liang
examines some of the duckweed under a microscope Brookhaven National Laboratory
One challenge lay in the fact that ordinarily, the gene
that pushes fatty acid production also stunts plant growth. In order to get
around that problem, the "push" gene was paired with another gene
known as a promoter, the latter of which is activated by adding a specific
chemical inducer to the water. "Adding this promoter keeps the push gene
turned off until we add the inducer, which allows the plants to grow normally
before we turn on fatty acid/oil production," said the lead scientist,
Brookhaven biochemist John Shanklin.
The researchers are now looking into methods of growing the
duckweed and extracting oil from it on a commercial scale.
A paper on the study was recently published in the Plant
Biotechnology Journal.
Source: Brookhaven
National Laboratory