COLLEGE STATION - Texas A&M University biologists are developing genetically modified rice resistant to insects and microbes, which could revolutionize the food and agriculture industries and help alleviate hunger in developing countries.
For many years, spraying insecticides on rice crops has been the best way to protect rice crops from insects. Scientists are now creating new strains of rice plants that would contain insect-killing proteins, so no insecticide would be needed.
"We are interested in killing insects that eat rice plants, like the rice water weevil," says Timothy C. Hall, distinguished professor of biology. "This insect feeds on the leaves and lays its eggs on them. When the eggs hatch, larvae grow and spend about a month chewing the roots."
To protect rice plants from water weevils, Hall and his colleagues insert insect-killing genes in the seeds of rice plants. Ideally, when the plants grow, these genes produce insect-killing proteins in the plant roots, preventing water weevils from eating the roots.
However, Hall and his group discovered that many of the insect-killing genes are not expressed or expressed only in the early stages of the growth of the plants. These genes -- also called transgenes -- are turned off once they are inserted in plants.
"This lack of expression -- also called gene silencing -- is a way for plant cells to protect themselves from invasion," Hall says. "When we put the gene in, it is seen by the plant cells as an invasive event, so there are various ways in which the cells turn off the expression of the foreign gene."
Hall and his colleagues are making new genes that would escape the gene silencing mechanisms.
"We want to create what we call stealth genes, basically genes that can get underneath the radar of the host cell protection," Hall says. "That involves understanding what the actual mechanisms of gene silencing are."
The silencing mechanisms are strategies by which plant cells in
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Contact: Timothy C. Hall
tim@mail.idmb.tamu.edu
979-845-7728
Texas A&M University
30-Nov-2000