In Crop Breeding, The Rice Is Right
New maps of the rice genome will make it easier for plant breeders to develop hardy, high-yielding versions of a variety of crops without the use of genetic engineering, scientists say.
The genetic blueprint of rice is similar to the genomes for corn, wheat and other plants descended from wild grasses. Plant geneticists say the rice map will make it much quicker to identify genetic traits and create new versions of crops by the old-fashioned method of cross breeding.
"The future of agriculture will be navigated using the rice genome map," said Steve Briggs, president of Syngenta AG's Torrey Mesa Research Institute.
Syngenta and a China-based group of researchers published in Science magazine Thursday draft maps of the genomes of separate subspecies of rice. A more complete map of the rice genome is nearing completion by an international consortium of scientists.
Rice is a staple for half the world's population, and the decoding of its genes is expected to help alleviate world hunger by making it easier for scientists to come up with varieties that are more nutritious and have higher yields.
This will be the first genetic mapping project "to yield tangible results for humankind from the standpoints of food security and combating malnutrition," the directors of two major international crop research centers wrote in a Science article accompanying the genome reports.
Stephen Goff, leader of the Syngenta team, said the variety it studied, known as japonica, should reveal the gene that causes production of vitamin A. That information could speed the development of rice varieties that have higher levels of the nutrient. Vitamin A deficiency is a major cause of blindness in Asia.
But the rice genome also is important because of the road map it provides for other crops with much more complex genomes, such as corn and wheat. Genes for traits such as resistance to heat or disease appear at similar locations in the genomes of all the related crops.
Conventional plant breeding is a laborious process, sometimes requiring a decade or more of crossing and back-crossing plants to ensure that the resulting crop variety has the best traits possible. Scientists say knowledge of the rice genome will enable them to find the genetic traits they want in seed banks and then to track those traits through the new plant varieties they're developing.
"It takes what is usually a 12 to 15-year activity to something that takes three or four years. That's pretty major," said Jeffrey Bennetzen, a biologist at Purdue University.
By using conventional breeding methods, crop developers avoid the hassle of getting government approval to test and commercialize genetically engineered crops. Biotech crops have met strong consumer resistance in Europe, and some U.S. food companies have shied from using them.
Syngenta plans to start field testing this summer a variety of corn that was developed using the rice data to be more resistant to cold, damp weather in the spring.
"Conventional plant breeding is going to be the major benefactor of the genomics era," said Benjamin Burr, a plant geneticist at the Brookhaven National Laboratory in New York.
The genome mapping suggests rice may have more genes than humans. The genome of the indica type studied by the Chinese group is believed to contain 45,000 to 56,000 genes, compared to 30,000 to 40,000 for humans. The japonica subspecies is believed to have 42,000 to 63,000.