Ames, Iowa
April 1, 2009
As a major food source for much of
the world, rice is one of the most important plants on earth.
Keeping it safe from disease has become, in part, the task of a
group of three researchers from
Iowa State University and one from Kansas State University.
The researchers are looking at two bacterial diseases of rice.
The most costly is bacterial blight of rice, which is caused by
a bacterium called Xanthomonas oryzae pathovar oryzae, and can
diminish yield by up to 50 percent.
"This is the most important bacterial disease in rice, and in
some areas, it is the most important rice disease of any kind,"
said Adam Bogdanove, an associate professor of plant pathology
who is part of the ISU research team.
The team is also studying bacterial leaf streak of rice caused
by the closely related bacterium Xanthomonas oryzae pathovar
oryzicola. Bacterial leaf streak is usually not as damaging as
bacterial blight, but it is increasing in importance in many
areas of the world, particularly Southeast Asia.
These bacteria damage rice by entering the plant and taking
control of certain rice cell processes, eventually killing the
rice cells. Pathovar oryzae does this in the vascular system of
the plant, which typically allows the bacterium to spread faster
and cause more damage than is its cousin, oryzicola, which is
limited to growth in the tissue between the veins.
Some types of rice are naturally resistant to the Xanthomonas
bacteria. Bogdanove and other researchers -- Bing Yang, Iowa
State assistant professor of genetics development and cell
biology; Dan Nettleton, Iowa State professor of statistics; and
Frank White, principal investigator and professor of plant
pathology at Kansas State University, Manhattan -- are
researching why some types of rice are naturally resistant to
the bacteria.
In rice varieties that are resistant to the diseases, the team
is exposing the plants to the two bacteria. They then check to
see which plant genes are activated, and to what extent.
By identifying which genes are turned on, Bogdanove believes the
team can identify the genes that are making the plants
resistant.
"We are looking at genes of successful plants," he said. "What
genes are active and when and how much they are being turned
on."
Bogdanove hopes that this effort will aid in breeding the
resistance into cultivated varieties that are currently
susceptible to the diseases.
Another aspect of the research is aimed at discovering how the
bacteria change gene expression in susceptible rice plants.
"If we understand which genes are being manipulated by the
pathogens in disease, we can look into different varieties and
wild relatives of rice for variants of these genes that are
immune to manipulation and bring these genes into cultivated
varieties," said Bogdanove. "The idea is to reduce or eliminate
susceptibility altogether."
Rice is the major food staple for more than half the world's
population. In the United States, rice is planted on almost 3
million acres with yields of around 7,000 pounds per acre in
2007, according the U.S. Department of Agriculture.
American producers grow 95 percent of the rice eaten in this
country and the United States is a major exporter as well,
according to Bogdanove.
In addition to the benefits to rice, the research should be
helpful in understanding and controlling diseases in other
cereal crops.
"Rice is a model plant for cereal biology," said Bogdanove.
Funding for the project comes from the National Science
Foundation through Kansas State University, the lead institution
on the project. Of the $3 million award for the project, $2
million is going to Iowa State. |
|
