Zhejiang University, Hangzhou,
China
March 19, 2008
Source:
Public Library of Science
(PLoS)
A method of creating selective
terminable transgenic rice was reported by the scientists of
Zhejiang University
in this week’s PLoS ONE. Unintended spreading of transgenic rice
by pollen and seed dispersal is a major concern for planting
transgenic rice, especially transgenic rice expressing
pharmaceutical or industrial proteins.
The transgenic rice plants created in the past usually can only
be detected by sophisticated molecular detection methods and it
is prohibitedly difficult to identify and selectively kill the
transgenic rice plants once they escape into environments and
contaminate conventional rice.
However, with the technology reported by Dr. Zhicheng Shen’s
group, the transgenic rice plants mixed in the conventional rice
could be selectively eliminated by a spray of Bentazon, an
herbicide commonly used for rice weed control.
This technology appears to be quite simple, reliable and
inexpensive for implementation. “If you use Bentazon for weed
control in your rice field, you do not need to worry about any
possible contamination caused by transgenic rice created by our
method. The herbicide will take care of it” said Dr. Shen, the
corresponding author of the article. “Containment of transgenic
crops only by physical isolation is not sufficient in our view,
as human errors, animal activities and nature accidents will
lead to the spreading of transgenic rice plants sooner or later”
added Chaoyang Lin, graduate student in Dr. Shen’s laboratory
and one of the leading contributors of the article. Indeed,
several major accidents of unintended spreading of the
transgenic crops did happen in the past several years in USA.
This technology may be best for use to contain transgenic rice
as bioreactors. “While all biotech products today are safe and
nutritious, this technology could allow certain crops targeted
for industrial, energy or health uses to be grown under
controlled conditions and kept separate from other channels”
said Nick Duck Vice President of Research for Athenix Corp. in
the USA.
The principle beneath this strategy is elegant and simple
according to the article. The genes of interest in these
transgenic rice plants will be linked with an RNAi cassette
which suppresses the expression of the rice detoxification
enzyme of Bentazon, rendering the transgenic rice to be
sensitive to the herbicide. Conventional rice is highly tolerant
to Bentazon.
Dr. Shen’s lab is currently using the technology for developing
transgenic rice as well as corn for expression of industrial
enzymes and pharmaceutical proteins. “We believe that transgenic
crops are the future, and we feel much better knowing that we
may release selectively terminable transgenic plants in the
future to address the concern of transgene spreading”, said Dr.
Shen.
A Built-In Strategy for Containment of Transgenic Plants:
Creation of Selectively Terminable Transgenic Rice
Lin C, Fang J, Xu X, Zhao T, Cheng J, et al. (2008)
PLoS ONE 3(3): e1818. doi:10.1371/journal.pone.0001818
http://www.plosone.org/doi/pone.0001818
Disclaimer
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Other news
from
Zhejiang University
|
New
method 'prevents spread of GM plants' |
|
March 28, 2008
by Jia Hepeng,
Sci.DevNet
Chinese scientists have developed
a strategy to identify and contain the potential release of
genetically modified (GM) crops into conventional plant
populations.
Shen Zhicheng and colleagues from Hangzhou-based Zhejiang
University modified a strain of rice to be susceptible to a
common herbicide used to kill unwanted GM plants in non-GM
fields. Their method was published in PLoS ONE last week (19
March).
Genetic modification can improve plant traits such as resistance
to pests and tolerance to harsh environments. But there are
worries that modified genes could leak into the wider
environment and enter the food chain.
Researchers and farmers have guarded against this by using
GM-free sections in fields, or engineering plants so that any
seeds produced from breeding are sterile.
But according to Shen and colleagues, these methods are not
enough to prevent contamination, particularly that caused by
human error — such as the planting of GM seeds in the incorrect
field.
The researchers used bentazon, a conventional, low-cost
herbicide to which rice and other crops, including cotton, have
natural resistance.
They blocked the expression of the enzyme that confers this
resistance, rendering the rice strain susceptible to the
herbicide. As a result, a single spray of bentazon at a regular
dose will kill any genetically modified rice plants.
"When we use this technique to target GM plants, we can simply
identify and kill the accidentally released GM strains without
hurting conventional plants," Shen told SciDev.Net.
Shen says these genes can be added to GM plants at the same time
as those added to improve specific traits, and so will not
significantly increase the cost of producing these plants
commercially.
But he adds that more work is needed to determine the proper
dosage of bentazon and evaluate the environmental impacts of
increased use of the pesticides.
Huang Dafang, former director of the Institute of
Biotechnologies of the Chinese Academy of Agricultural Sciences,
says the method offers a creative scientific approach to GM
plant containment.
"But, in practice, better field management and pollination
control could be more easily operable and economically more
advantageous," says Huang, adding that studies are also needed
to identify the possible interaction between modified genes in
the GM containment strategy. |
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