During any given year, yield losses resulting from flooding in theselowland areas may range from 10 percent to total destruction,depending on the water depth, age of the plant, how long the plantsare submerged, water temperature, rate of nitrogen fertilizer use andother environmental factors. Annual crop loss has been estimated atmore than $1 billion.
"For half a century, researchers have been trying to introducesubmergence tolerance into the commonly grown rice varieties throughconventional breeding," said rice geneticist and study co-authorDavid Mackill, who heads the Division of Plant Breeding, Genetics,and Biotechnology at the International Rice Research Institute."Several traditional rice varieties have exhibited a greatertolerance to submergence, but attempts to breed that tolerance intocommercially viable rice failed to generate successful varieties.
"We're especially pleased that we have been able to use the latestadvances in molecular biology to help improve the lives of theworld's poor," Mackill added. "We're confident that even moreimportant discoveries like this are in the pipeline."
Results of this study
Using genetic mapping techniques, the research team identified acluster of three genes that appeared closely linked to the biologicalprocesses that either make rice plants vulnerable to flooding orenable them to withstand the total submergence that occurs duringflooding.
The researchers then focused their attention on one of those threegenes, known as the Sub1A gene. They found that when this gene isover-expressed, or hyper-activated, a rice variety that is normallyintolerant of submergence becomes tolerant.
Further studies indicated that the Sub1A gene is likel
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Source:University of California - Davis