Scientists develop high-yield deep water rice

A team of Japanese scientists has discovered genes that enable rice to survive high water, providing hope for better rice production in lowland areas that are affected by flooding.

Wednesday, August 19, 2009
By ERIC TALMADGE
Associated Press Writer

TOKYO — A team of Japanese scientists has discovered genes that enable rice to survive high water, providing hope for better rice production in lowland areas that are affected by flooding.

The team, primarily from the University of Nagoya, reported their findings in Thursday's issue of Nature, the science magazine.

The genes, called SNORKEL genes, help rice grow longer stems to deal with higher water levels. Deep-water rice generally produces lower-yield rice plants. But the researchers report they have succeeded in introducing the genes to rice varieties that are higher-yield.

According to the report, as water levels rise, accumulation of the plant hormone ethylene activates the SNORKEL genes, making stem growth more rapid. When the researchers introduced the genes into rice that does not normally survive in deep water, they were able to rescue the plants from drowning.

Motoyuki Ashikari, who headed the project, said his team is hoping to use the gene on long grain rice widely used in Southeast Asia to help stabilize production in flood-prone areas where rice with the flood-resistant gene is low in production - about one-third to one-quarter that of regular rice.

"Scientifically, the gene that we found is rare but clear proof of a biological ability to adapt to a harsh environment," he said. "It's a genetic strategy specifically to survive flooding."

Ashikari said his team already successfully tested the gene on a Japanese "Japonica" rice, and his team now plans to create a flood-resistant long grain rice in three to four years for use in countries such as Vietnam, Thailand, Myanmar, Bangladesh and Cambodia.

High water levels in paddies can be a serious problem. In some areas, rains can cause water levels to rise dangerously high during the growing season and flash flooding can fully submerge plants for days or even weeks.

Rice is a staple food for billions, and while productivity has increased dramatically since the 1960s, yields must be doubled to meet projected requirements by 2050. More than 30 percent of Asian and 40 percent of African rice acreage is cultivated in either lowland paddies or deepwater paddies.

Laurentius A. C. J. Voesenek, at the Institute of Environmental Biology, Utrecht University, who was not part of the research team, said the study is significant because high-yield rice varieties cannot survive extremes of inundation.

"The introduction of (these genes) into high-yielding varieties, using advanced breeding strategies, promises to improve the quality and quantity of rice produced in marginal farmlands," he said in a review of the paper, also published in Nature.

Rainy-Day Rice Asian farmers will get a disaster-proof version of an essential crop

Wet Work: Farmers plant rice seedlings in Thailand Philip Blenkins/Getty Images

12.18.2008
By Melinda Dodd
Popular Science

After years of testing in muddy fields, genetically enhanced flood-resistant rice is about to hit agricultural markets in tropical Asia, following Indonesia, with India and Bangladesh up for approval later this year. Cambodia, Laos, Nepal, Thailand, the Philippines and Vietnam are expected to follow suit.

It's a major step forward for weatherproof crops, increasingly touted as essential to the long-term future of the world's food supply. Advances in biotechnology have improved this ancient grain, which accounts for up to 70 percent of daily calories for people living in Asian countries. Imperiled by constant floods, rising sea levels and natural disasters, submerged rice survives just four days when deprived of light and oxygen. These new varieties last eight to 18 days.

The advance is urgently needed. "At least [58,000 square miles] of land in South and Southeast Asia are vulnerable to flooding, and floods will only increase," says Dave Mackill, a senior scientist with Manila's International Rice Research Institute (IRRI). In 2007, Cyclone Sidr destroyed 1.25 million tons of rice in Bangladesh; last year, multiple typhoons wiped out rice paddies in Vietnam.

To find a suitable template for the flood-resistant rice, Mackill turned to India's water-tolerant FR13A rice. Farmers stopped using the strain because of its poor yield, but its resilience intrigued him. To pinpoint the part of the rice genome carrying the trait, Mackill crossbred a hardy derivative of FR13A with another rice strain and derived 4,000 other rice plants from that cross. Geneticist Pamela Ronald of the University of California at Davis then searched the plants' DNA and unearthed Sub1A, a gene that triggers the grain to conserve energy when it is underwater. To create the final rice strain, Mackill cross-pollinated a Sub1A-containing plant with a high-yielding, better-tasting Indian rice variety.

In the coming years, IRRI researchers will supplement Sub1-class rice with a gene that resists flooding during the sensitive germination stage (something the Sub1 genes can't do). Also on the agenda: drought- and salt-resistant rice, now testing in nearly every Southeast Asian tropical country and China. Asia's inland and coastal areas often have salt-filled soil, which stunts rice growth.

The IRRI has already made its rice seed available to other research institutions and has been distributing it to Asian farmers for free. When sold by other seed growers on the commercial markets, the price should rival that of common varieties. "We anticipate adoption wherever submergence is a regular problem," Mackill says. If the rice is a success, climate-resistant crops may spread across the developing world, as well as the developed.