RICE farmers will soon be buying cheap hybrid seeds produced by genetically modified plants if an Indian biotech company has its way. It has patented its own way of producing new hybrid varieties, and is betting its products will not meet the same opposition as GM crops produced by multinationals like Monsanto.
Hybrid crops, produced by crossing different varieties, are widely used in agriculture as they are usually more vigorous and produce higher yields. To create hybrids, plant breeders must prevent the parent plants from pollinating themselves. Doing this by hand is labour-intensive and costly, so breeders prefer to use male-sterile strains that cannot make pollen.
But there may be few, if any, natural male-sterile strains for any one crop. And relying on just one can make a crop vulnerable to disease, as the US discovered in the 1970s when its hybrid maize, produced from the “Texas” male-sterile line, was devastated by a fungus. So researchers have instead turned to genetic engineering. Biotech giants such as Aventis have created new male-sterile lines of maize, canola and chicory, usually by adding a bacterial gene called barnase that is turned on only in pollen-producing cells and blocks pollen production by chewing up RNA.
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Now Avestha Gengraine of Bangalore has been granted a USpatent on a rival technique for making male-sterile lines that relies on a curious phenomenon called RNA editing. In some plants, the cells’ energy-producing mitochondria alter the genetic sequence of RNAs encoded by some mitochondrial genes before they are used as a template for making proteins. This happens with the gene nad9, which codes for a key mitochondrial protein.
Avestha adds the nad9 gene from the cress Arabidopsis thaliana to the nucleus of rice cells, along with a sequence telling the cell to transport the resulting nad9 protein to mitochondria. Because RNA from nuclear genes is not edited, this protein is faulty and disrupts energy production in mitochondria. As a result, the plants produce no pollen.
The mutations in many natural male-sterile plants are thought to disrupt energy production in a similar way. For commercial seed production, fertility can be restored to Avestha’s plants by adding an “antisense” version of the nad9 gene to the nucleus.
The company claims that the technique, tested in basmati rice, could halve the time it takes to create new hybrid varieties of cereals, fruits and vegetables, thus reducing the price of seeds. A greater variety of male-sterile lines will also reduce hybrid crops’ susceptibility to diseases and pests, says the head of Avestha, Villoo Morawala Patell.
She is confident the company’s GM hybrids will not encounter the same opposition in India as other GM crops. “When I founded the company, I deliberately positioned it as a home-grown company that can generate intellectual property for India and support domestic agriculture.”
But in 1993 the French national research agency CNRS patented a very similar method of producing male-sterile plants. CNRS allowed the patent to lapse in 2000, says Armand Mouras, one of the researchers, because opposition to GM crops in Europe meant no one wanted license the method.