Key to boosting rice crops in fungal genome?
destructive enemy of the world's staple food crop rice, a fungus
called Magnaporthe grisea that causes rice blast disease.
In a paper published in the 21 April issue of Nature, researchers in the US shed some light on the adaptations required by a fungus to destroy massive areas of rice crops.
The scientists have identified novel receptors that allow the fungus to recognise its environment; secreted proteins that are likely used as offensive weapons to damage rice plants; and redundant, or duplicate, mechanisms that protect the fungus from efforts to fight against it.
"It's a clever system," says Dr. Ralph Dean, professor of plant pathology at North Carolina State University's Center for Integrated Fungal Research, and lead author of the research paper.
Bringing the fungus genome 'to life' could enable science to designs actions to stop this harmful rice pathogen from destroying massive quantities of valuable food sources.
According to the researchers, rice blast, the leading cause of rice loss, each year kills enough rice to feed 60 million people worldwide.
But rice is the staple food for over half of the world's population. Projections from the UN-backed Food and Agriculture Organisation (FAO) show that by 2030, total demand for rice will be 38 per cent higher than the annual amounts produced between 1997 and 1999.
And in order to meet future demand, new methodologies and production technologies, and a greater knowledge of threats such as Magnaporthe grisea, will be necessary as land and water resources are increasingly denuded.
Tracking the genome of this harmful pathogen should give researchers "a better idea of what types of genes are involved in making the toxin molecules", says Dean.
Some of these genes reside in clusters, Dean reports, so one focus will be to take apart the clusters and learn more about toxins and their production.
"The primary mission is to uncover the organism's weaknesses. You do that by building up an arsenal of information of what genes are involved in plant-pathogen interactions," adds the lead author.
In July 2002, Dean and researchers from the Whitehead Institute at MIT, now called the Broad Institute, issued a preliminary genome sequence of M. grisea.
"That work decoded the string of letters that comprise the genome. This paper shows the work of the last two years in bringing this genome to life," says Dean.
Bringing the genome to life means capturing the biological meaning of the genome, Dean says. To do this, he and his colleagues used two strategies: comparative genomics and functional genomics.
"M. grisea contains about 11,000 genes, so you can't look at every one," adds Dean. "The comparative study allows us to look at novel classes of genes and novel proteins and prioritise study efforts."
The US department of agriculture predicts global production of rice to reach 401.8 million tons (milled basis) in 2004/05, up 10.8 million tons from 2003/04.
Global consumption continues to outpace production and is expected to grow 5.2 million tons to 417.9 million. Consequently, ending stocks are projected to plunge 16.1 million tons, with substantial declines expected in China, Thailand, and Vietnam, implying stronger prices throughout the 2004 and 2005 trade years.
