Source: News@Nature.com via Meridian Institute Food Security and Ag-Biotech News 6/28/2005
Author: Emma Marris

Researchers from Japan and China have developed a new high-yielding rice variety through a combination of traditional plant breeding and modern biotechnology.

The recent availability of the sequenced rice genome allowed the researchers to investigate areas of the genome that influence productivity. They found, for example, that a gene in one particular area of DNA produces an enzyme that degrades a seed-production hormone.

The researchers used a form of cloning to develop rice plants in which this gene's activity was reduced, and these plants were found to have higher levels of overall seed production. Once this had been ascertained, the researchers developed an improved variety of rice through traditional plant breeding.

Their new rice variety produces 25 percent more seeds than Japan's most popular Koshihikari rice variety, which is one of its parents. The researchers say that although their rice plants are not genetically engineered, they believe that genetic engineering may be a useful tool for improving crop yields.

"Our approach is one of the powerful methods. However it is not all-powerful," says Motoyuki Ashikari of Japan's Nagoya University. The researchers suggest that genetic engineering might one day be employed to move useful areas of DNA from rice into other crops, such as wheat and soy.

Their findings were published June 23 in the online edition of the journal Science.

[In the article from Science, the researchers comment that approaches like theirs that involve "discovering useful genes, improving agricultural traits hidden in the plant genome, and applying these findings to crop breeding will pave the way for a new green revolution." They say that traits native to wild rice species offer special promise.]

Article: www.nature.com/news/2005/050620/full/050620-13.html

Related news release from Nature

Biologists say they have built a better rice plant: one that is heavy with seeds, but not so tall that it will fall over in the rain.

The work is expected to help increase yields of rice, which is the staple grain for the majority of the world's population. The many-seeded variety is less likely than others to bend double in high winds or rain, and this keeps the tops out of the water and reduces their chance of rotting.

The new plant was made possible through a mix of modern and old-fashioned techniques. First, the recent availability of the rice genome allowed the researchers to investigate areas of the plant's DNA that influence productivity. Motoyuki Ashikari of Nagoya University and Hitoshi Sakakibara of RIKEN in Yokohama, along with their colleagues, were able to determine that a gene in one particular area of DNA, for example, produces an enzyme that degrades a seed-production hormone.

If this gene isn't very active, and produces only a small amount of the enzyme, then the hormone builds up and encourages the plant to pump out more seeds. This was confirmed by genetically altering individual plants to express this gene to varying degrees.

Armed with this knowledge, the team then produced an improved variety of rice the old fashioned way - through traditional breeding. They selected two breeds: one well known for producing lots of seeds, and one that tends to be short. They then screened successive generations of rice plants for the areas of DNA they knew to influence these traits, in order to select the best plants to cross with each other. The results of four years' work in the lab and field appear online in Science¹.

Cream of the crop

The researchers stress that although their plants are not genetically engineered, they believe that genetic engineering may be a useful tool to improve crop yields. "Our approach is one of the powerful methods. However it is not all-powerful," says Ashikari. Genetic engineering might one day be employed to move useful areas of DNA from rice into other crops, such as wheat and soy, they suggest.