Making Rice Disease-Resistant
Posted September 14, 1998
One third of the world's population, over 2 billion people, depend on rice for basic nourishment. It is one of the world's most important foods. Across the globe
360 million acres of land are devoted to growing rice, producing 560 tons annually. However farmers plant much more rice than they actually harvest. A sizable portion of the crop is
lost due to insects, bacteria, viruses and fungi.
One of the most devastating diseases is blight. Blight is caused by a species of bacteria, Xanthomonas oryzae, or Xoo for short , that can destroy half
a rice farmer's crop in a few days. This disease spreads quickly because it can be transmitted in water droplets. This disease is virtually impossible to control, since rice is grown
in shallow waters or rice paddies.
However, in the past several years researchers at Cornell University in Ithaca, New York, have been trying to develop a rice plant that would be resistant to bacteria.
Different varieties of rice have resistance to different diseases. Unfortunately there is not a cultivated species of rice that is resistant to blight. The researchers at Cornell are
trying to genetically engineer a resistant rice plant. They have found a blight resistant gene, Xa21 in a species of wild rice. A gene is a sequence of DNA. In order to change the genetic
make up of the cultivated rice; the scientist had to find a way to get the Xa21 gene or DNA into the plants cells. They actually shot the DNA into the cells using a special gun. The
"bullets" were tiny pellets (less than 1/100 of a mm) of gold that were coated with the Xa21 gene DNA. The pellet carried the Xa21 gene into the plant cells. The scientist used tissue
cultures to grow rice plants from these resistant cells. The plants were exposed to the Xoo bacteria. The ones that were resistant became the parents of a new generation of blight
resistant rice plants. The Cornell scientists are currently working with rice farmers in Asia and Africa, field testing the blight resistant rice.
Transgenic plants may have a significant impact on farming in this country. Imagine the citrus fruit crops that could be produced if scientists were able to insert
a frost-resistant gene into citrus trees. Farmers spend millions of dollars each year irrigating their crops. What if scientists were able to produce plants that were drought-resistant?
The possibilities seem endless, and there is no doubt that we will be hearing more about transgenic plants in the future.
Activity: Use the Internet to find examples of other uses of bioengineering in agriculture and industry. Choose one use too follow. Keep a journal to track the development
of the technique over a period of time. Report your findings to your class.
Ronald, Pamela. "Making Rice Disease-Resistant," Scientific American, Vol. 277, November 1997, pp. 100-105