Gene leakage

GM bacteria can infect fungi

By Jyotika Sood
Published: Wednesday 15 December 2010

A BACTERIUM, which the biotech industry uses as a vehicle to insert foreign genes in plants, can alter the genetic makeup of other life forms like fungi in the environment, shows a research by UK scientists. This is a way, apart from cross pollination, modified genes could escape into the environment, said the researchers. They call for considering the finding during the risk assessment of bacteria-mediated genetically modified (GM) plants.

imageThe soil bacterium, Agrobacterium tumefaciens, causes a tumour, crown gall, in plants. As it infects, it triggers the secretion of a hormone, acetosyringone, in the plant and transfers its genetic material into the plant cell, causing tumours. Scientists know which section of the bacterium’s DNA gets transferred during the infection.

They remove disease- causing gene from the section, replace it with new or synthetic gene, and expose the modified bacterium to a plant cell in the presence of acetosyringone, thus generating GM plants like Bt cotton and Bt brinjal. The sturdy modified bacterium can survive within the plant.

Previous studies showed the modified bacterium can also alter genes of living forms like human cells and fungi, but only in the lab where it is supplied with sufficient acetosyringone. No study was done to show if the transformation is possible in the wild. Claire Knight, a research student at University of Bristol in the UK, found such transformation is also possible in the natural environment.

She studied various plants grown in the lab and found plant wound sites produce enough acetosyringone to enable the bacterium transfer its genes to a commonly found fungal pest, Verticillium albo-atrum. Gary Foster, Knight’s guide in the research, said the fact was previously overlooked and could have potentially leaked modified genes into the environment. In most cases the modified genes would not help the fungus survive. But it can be potentially harmful if, for example, the modified bacteria spread genes that confer pesticide resistance to the fungal pest, Foster noted in the October 27 issue of PLoS ONE.

Andy Bailey, a coresearcher, said the bacteria should be completely removed from GM seeds before they leave the lab and seed companies must ensure this. Biotech companies that produce GM crops claim they treat GM seeds with antibiotics to remove Agrobacterium before releasing the seeds to farmers. Suman Sahai of Gene Campaign, a research and advocacy organisation in Delhi, doubts. “Removing the bacteria from GM seeds with cent per cent accuracy is not possible,” she said.

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