Brussels, Mar 2006
UK scientists have made a breakthrough in the understanding of how rice blast fungus operates. Rice is the staple food for more than half of the world's population, and the rice blast fungus is its most lethal enemy. The rice blast fungus is estimated to destroy enough rice to feed 60 million people - equivalent to a country the size of Britain, France or Italy - every year.
The research, carried out at the University of Exeter in the UK, focused on the rice blast fungus genome, to find candidate genes that could be responsible for its toxicity. The blast fungus (Magnaporthe grisea) is parasitic, attaching itself to the rice plant, invading it, and then slowly digesting it from the inside with toxic enzymes. The fungus has been shown to have a high resistance to fungicides and efforts to control its spread have mixed results.
'This is a very important disease of rice and we've been able to show how it delivers its 'weapons' into a rice plant to cause disease. We believe this is something of a breakthrough because it's the first time that we've been able to learn something about the process of how the disease happens,' said lead researcher Professor Nicholas Talbot in an interview with the Independent newspaper.
The discovery could lead to specially bred strains which are resistant to the fungus, or special fungicides which could specifically target the disease. In the lab, the team produced a modified version of the rice blast fungus that was unable to cause the disease. 'The discovery is significant because it will allow us to identify the fungal proteins which bring about this devastating disease and cause rice plants to die,' said Professor Talbot.
The gene identified is known as MgAPT2. The gene sequence was removed from a strain and replaced with a code for hygromycin resistance. Although the modified fungus seemed to spore and develop as normal, the number of infected rice plants in the lab was reduced by more than 95 per cent.
The next step will be to investigate in greater depth the 'effector proteins' essential for the disease. A solution to the problem of rice blast fungus could now be five to ten years away.