EXPLOSIVE Plant Science!

Although typically associated with developing enhanced food crops, GM technology has a wealth of potential applications. One of the most inspiring talks (to my mind at least) at the UK PlantSci conference was that of Elizabeth Rylott (University of York): “Plant Cillit Bang! And the dirt is gone! Using TNT to understand detoxification of organic pollutants by plants”. Trinitrotoluene (TNT), a potent carcinogen, is a pollutant released from explosive materials and which contaminates approximately 10 million hectares in the USA (especially around military zones), poisoning groundwater sources. Plants are naturally able to detoxify low levels of TNT, using enzymes which “activate” the functional groups on TNT. This then allows enzymes called uridine diphosphate (UDP) glycosyltransferases (UGTs) to transfer the activated groups to an acceptor molecule, converting TNT into a less toxic compound.  Transgenically over-expressing these enzymes can reduce the levels of TNT in plants grown on contaminated soil. A problem, however, is that TNT often occurs in nature alongside cyclotrimethylenetrinitramine (RDX), which plants cannot detoxify. Nevertheless, RDX detoxifying enzymes have been identified in bacteria, including a cytochrome p450 monoxygenase in Rhodoccocus. When this is introduced into plants already engineered for enhanced TNT detoxification, the result is “super plants” capable of restoring contaminated soil. Such “bioremediation” strategies are becoming increasingly popular and could play a part in turning public opinion in favour of GM. Indeed, these plants were capable of removing all RDX from the surrounding soil within a week. Rather than just accumulating toxic RDX in the leaves, however, these plants convert it into a source of nitrogen – which they then use to fertilise their own growth! Hence, RDX does not simply move from the soil to the plant, but is converted into a completely harmless form.

Professor Elizabeth Rylott and her amazing transgenic switchgrass

So could this be a message of hope to those millions of devastated acres tainted with explosives? Excitingly, this research has now moved to the field trial stage in the USA, using transgenic switchgrass. Amusingly, part of the preparations for these trials involved packaging the seed into soil plugs and dropping these off the roof of the lab… apparently, the military strategy for planting the transgenic plants will be to drop them from a helicopter, hence the team had make sure the plants could stand up to this treatment!

A crucial experiment...making sure the seed plugs can survive the impact of being dropped by a helicopter

And just in case you were wondering... the above is all true and NOT an April Fool!