SciDev.Net

The scientists modified a strain of rice to be susceptible to a common herbicide

IRD / Michel Dukhan

[BEIJING] 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.

Link to the full paper in PLoS ONE