Reuters 19 Aug 09;
HONG KONG (Reuters) - Researchers in Japan have identified two genes that make rice plants grow longer stems and survive floods, and hope this will enable farmers to grow high-yielding rice species in flood-prone areas.
The long-stemmed deepwater rice varieties grown at present in areas of frequent flooding have very low yields.
"In southeast Asia, there are floods in the rainy season and deepwater rice is planted in these regions. But they have yields that are only one third or one quarter that of high-yielding rice. This is a big problem," said Motoyuki Ashikari at Nagoya University's Bioscience and Biotechnology Center.
"If we combine the deepwater genes with high-yielding rice, we can have the best combination," he said in a phone interview.
In their experiment, Ashikari's team analyzed the genes of a deepwater rice variety and found two genes that were unique to the plant.
"The genes Snorkel 1 and Snorkel 2 are only in the deepwater variety but not in the non-deepwater variety," he said.
They discovered that rice plants begin producing a lot of the plant hormone ethylene when grown in deep water.
"As water levels rise, accumulation of the plant hormone ethylene triggers expression of the Snorkel genes, which in turn switches on rapid stem growth," they wrote.
They later tested their findings by inserting the two genes into a non-deepwater variety of rice and found that it grew longer stems, enabling it to survive in deep water.
"It's hoped that the findings will help researchers to breed rice that can be grown in lowland areas that are frequently flooded during the rainy season," they wrote in a statement.
(Reporting by Tan Ee Lyn, editing by Tim Pearce)
Scientists develop high-yield deep water rice
Eric Talmadge, Associated Press Yahoo News 20 Aug 09;
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.
Snorkel rice could feed millions
Sudeep Chand, BBC News 19 Aug 09;
A new rice plant has been developed which grows "snorkels" when exposed to floods.
A paper in the journal Nature, describes how the plant elongates rapidly in response to being submerged.
One of the scientists, Motoyaki Ashikari from Nagoya University in Japan, said "the impact is huge".
It could also boost the production of rice in Asia and Africa, where up to 40% of crops are subject to flash floods or deep water.
"People cannot plant any crops in the rainy season, because the crops drown and die in the floods," said Mr Ashikari.
Writing in Nature, Laurentius Voesenek describes how the Japanese scientists discovered the "snorkel" genes in flood-tolerant rice, and introduced them to more sensitive high-yield rice.
"Snorkels" grow as hollow tubes from parts of the plant called internodes, preventing it from drowning.
When the floods arrive, the super rice plants can grow up to 25cm per day.
