Washington, DC
February 17, 2009
In 2008, headlines of real world
events read like the script of a bad science fiction movie – the
main food source of half the world was in short supply, sparking
riots around the globe. But new research may help shield rice
crops from future attacks.
Rice is a tiny cereal grain that is the primary source of food
for more than 50 percent of the world’s human population. It is
the second most consumed cereal grain and provides more than
one-fifth of the caloric intake of people around the world.
Fearing a global shortage, many governments and retailers began
rationing rice supplies, which led to the events in the
headlines.
The importance of this grain to the world community is clear. It
is also important to science; the rice genome was one of the
first cereal crops sequenced.
Scientists use rice as a model for research of other cereals
because it has a relatively small genome compared to other
cereals. The diminutive rice genome is one-sixth the size of the
maize genome and 40 times smaller than the wheat genome. The
complete sequence of the domesticated rice variety, Oryza sativa
spp. japonica, was finished in 2004.
Despite all of the progress in mapping the rice genome, the
function of individual rice genes lags far behind the same
studies in other cereal crops. Now, with funding from USDA’s
Cooperative State Research, Education, and Extension Service (CSREES),
scientists in California have cataloged the different techniques
available to determine the function of genes in rice.
Pamela Ronald and colleagues at the University of
California–Davis and Postech, Korea, provide a complete analysis
of all of the tools and publically available collections for
this important agricultural crop to the scientific community.
These tools will help scientists delve into the rice genome and
discover the function of the estimated 41,000 rice genes.
“[The] tools include rice lines that are lacking function of one
or more genes, methods for assaying the expression of genes in
different environments, and databases to catalog rice gene
function,” Ronald said.
A genome, the total of all genes that make up the genetic code
of an individual, is like a brick building where genes are the
individual bricks in the building. A gene is the basic unit of
inheritance.
Currently, the scientific community has identified forms of
genes that confer fungal and bacterial resistance, as well as
genes that make the grain tolerant of submergence and other
stresses. Genes responsible for flowering, nutrient transport,
and biochemical pathways play a critical role in plant growth
and development, as well as establish the environmental
parameters under which the crop thrives.
Research on gene function may provide additional protection to
the rice crop from attack from bacterial, fungal, and insect
pests. Deciphering gene function may also increase plant growth,
crop production. and expand the plant’s environmental tolerance,
allowing it to thrive under a new set of conditions dictated by
changing climate, including drought, flood, and increased carbon
dioxide concentrations.
For example, a gene called Sub1 has already been used to develop
new rice varieties that are tolerant to submergence, a problem
that affects 75 million poor farmers in south and southeast
Asia. These Sub1 varieties, developed in collaboration with
breeders at the International Rice Research Institute, are now
showing dramatic gain yields in farmers’ fields in Bangladesh.
Deciphering the function of genes in the rice plant will ensure
the supply remains bountiful in the future. The knowledge gained
from these studies can be transferred to other important cereal
crops as well as bioenergy crops, such as switchgrass.
CSREES funded this research project through the National
Research Initiative Plant Genome program. Through federal
funding and leadership for research, education and extension
programs, CSREES focuses on investing in science and solving
critical issues affecting people’s daily lives and the nation’s
future. For more information, visit
www.csrees.usda.gov.
By Stacy Kish |
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