Scientists have discovered how a fungus manages to invade rice plants, causing a disease that destroys enough rice each year to feed 60 million people.

The discovery could help researchers develop specific, environmentally friendly chemicals to fight the fungus, says lead researcher Nick Talbot of the University of Exeter, United Kingdom.

In a paper published tomorrow (23 March) in Nature, Talbot's team show that the fungus, Magnaporthe grisea, uses a single protein called MgAPT2 to gain entry into rice leaves or roots.

This allows the fungus to deliver a series of additional proteins that suppress the plant's defences and cause rice blast disease, the most destructive and costly disease of rice.

When the researchers blocked the gene that makes MgAPT2, they found that the fungus was no longer able to cause disease.

In 2002, researchers led by Ralph Dean of North Carolina State University, United States mapped the fungus's genetic code (see Genetic secrets of rice's worst fungal pest unveiled).

Dean told SciDev.Net that to cause disease the fungus must first detect its host, and that proteins it secretes play a major role in this process.

Of Talbot's research, Dean says "it is very exciting and rewarding to identify a major component of the [fungus's] machinery that directs ... proteins out of the fungal cell to attack the plant."

Link to full paper in Nature

Reference: Nature 440, 535 (2006)