New rice uses built-in RNAi to control gene flow
A team of Chinese researchers has developed a method for controlling the spread of transgenes from genetically modified rice to weedy relatives. The new rice exploits RNA interference (RNAi) to inhibit the expression of an enzyme, CYP81A6, that in rice detoxifies the herbicide, bentazone. It contains an expression cassette comprising an RNAi sequence targeting endogenous expression of CYP81A6 and two further transgenes, an enolpyruvylshikimate phosphate synthase (EPSPS) that confers tolerance to the herbicide, glyphosate, and a Bt Cry1Ab insecticidal toxin effective against lepidopteran pests. All three sequences are tightly linked so that they are transmitted together. Plants and progeny are tolerant to glyphosate but sensitive to bentazone at recommended application rates. Hybrids of the GM rice and weedy rice were also killed by bentazone.