June, 2004
No single strain of wheat, barley, or related species completely withstands Fusarium Head Blight, a disease that is making increasing inroads on health and harvests worldwide. A new project offers better methods and broader gene pools for finding genes to ward off the disease.
Fusarium Head Blight (FHB), one of the most destructive wheat diseases in warm and humid regions, seriously threatens wheat and barley production around the world. Even worse, the toxins produced by Fusarium fungus cause acute food poisoning in people and harm animals that eat infected grain.
A new five-year-long collaborative project between CIMMYT and the government of Japan aims to discover genes that control FHB resistance, identify wheat germplasm that can be used in FHB resistance breeding programs, and develop FHB resistant wheat by using DNA markers.
Scientists in Japan began conducting genetic and breeding studies on FHB resistance in the 1960s, after an epidemic swept across more than 400,000 hectares in 1963 and caused estimated yield losses of more than 50%. More recent epidemics in 1996 and 1998 affected about 26% of the land in Japan. Developing countries also suffer losses from FHB, and CIMMYT started its own breeding program on FHB resistance about 20 years ago.
In the United States, FHB is the worst plant disease to emerge since the 1950s, according to the United States Department of Agriculture. In the 1990s, epidemics in seven US states caused more than US$ 1 billion in crop losses. Partly due to climate changes caused by global warming and the increased use of reduced tillage practices, FHB has become more widespread in recent years.
Sources of resistance to the disease have been elusive. Researchers have never found an accession of wheat, barley, or their wild relatives that is completely immune to FHB, according to Tomohiro Ban, a scientist at Japan International Research Center for Agriculture Sciences. A lack of good sources of resistance and good methods for finding them prompted the government of Japan to fund the new project with CIMMYT, which Ban is now leading at CIMMYT-Mexico.
The genetic constitution and chromosomal location of FHB resistance genes are not well known, but current research suggests that several quantitative trait loci or minor genes control resistance. DNA markers could identify and evaluate these genes. It is hoped that the project’s search for resistance genes will also advance because of access to CIMMYT’s genebank, which has one of the world’s largest collections of wheat and its wild relatives. Researchers will be able to screen materials from a great diversity of gene pools and environments.
“We are going to use the untapped potential of these diverse genetic resources and find new sources of resistance,” says CIMMYT Director General Masa Iwanaga. Even more important, the program could become the focus for a more organized worldwide effort to combat the disease. “We would like to facilitate a platform for international collaboration, because this is a global problem,” comments Iwanaga.
For information: Tomohiro Ban
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