Chapter Eight: Rice Biotechnologies: Issues and Impacts
8.3 Rice Biotechnologies for Asia
Over the last 40 years, plant scientists at IRRI have continued to develop new rice varieties to improve rice production. Their primary goal has been to increase rice production using less land and water and relying less heavily on agrochemicals. IRRI has also sought to provide technologies to rice growers in unfavorable growing environments, to boost rice production in those parts of the world that rely most heavily on rice as their dietary staple. Originally, IRRI researchers used traditional plant breeding, a hit-or-miss process that can require numerous combinations and generations of plants to establish a plant line with the right combination of desirable traits. Traditional plant breeding is also limited because only those plants that can naturally breed with one another can be crossed.
In the 1980s, rice scientists at IRRI and in privately owned plant research companies began incorporating the tools of biotechnology to develop new rice varieties with enhanced properties. In present-day rice research, scientists are using genetic engineering (in combination with traditional plant breeding and other tools of molecular biology) to insert genes into rice varieties to design cultivars which can survive the various environmental challenges found in rice fields.
Abiotic stress refers to threats from non-living factors, such as drought, salty soils, or freezing temperatures . Biotic stress refers to living organisms that harm crops, like insects, bacteria, or fungi.
Like all field crops, rice is threatened by insects, weeds, diseases, and abiotic stress . Why do we care about creating rice that is not harmed by environmental factors? The answer is that rice plants become stressed when they are eaten by bugs, attacked by bacteria or fungal infections, drowned by untimely floods, withered by drought or salty soils, or overcrowded by weeds. Stressed plants don't produce very many rice grains. Poor rice harvests lower farm incomes at the least, and can cause severe food shortages at worst. However, rice plants that are less affected by environmental stresses yield better harvests.
The first biotech rice expected to be commercially grown in Asia is insect-protected transgenic rice . By inserting Bt genes, Bt- rice has been designed to resist several species of stem borer, which cause significant crop losses in Asian rice fields. Bt- rice has been a continued emphasis of government plant scientists in China , where it has been field evaluated for several years.
Rice plants in the field can be threatened by bacterial infection. One of the most damaging bacterial infections in rice is bacterial leaf blight . Rice plants infected with bacterial leaf blight become waterlogged, rot, and produce few, if any, rice grains. A gene called Xa21 which protects African rice plants from bacterial blight has been isolated and transferred into rice varieties grown in Asia . GM rice varieties with the Xa21 gene are being field evaluated for agronomic performance and screened for environmental and health safety.
Other genes that give field plants a competitive edge have been identified and isolated, and are now being transferred into rice using recombinant DNA techniques. These genes can increase photosynthesis in plants and provide protection against abiotic stresses such as drought, salty soils and low temperatures.
Two other areas in which biotechnology has been applied to rice are herbicide resistance and nutritional enhancement.
Instant Replay..
Define abiotic and biotic stress . List some examples of abiotic and biotic stresses.
Web search: Go to www.irri.org . Follow the Science Online link to World rice statistics. Click on IRRI's Atlas of Rice. Click the search button. Select the Philippines as the location and RiceMap as the map service. Click basic map. Which rice varieties are grown in the Philippines.
This project was supported by Initiative for Future Agriculture and Food Systems
Grant no. 2001-52100-11250 from the USDA Cooperative State Research, Education, and Extension Service
Rice plants in the field can be threatened by bacterial infection. One of the most damaging bacterial infections in rice is bacterial leaf blight . Rice plants infected with bacterial leaf blight become waterlogged, rot, and produce few, if any, rice grains. A gene called Xa21 which protects African rice plants from bacterial blight has been isolated and transferred into rice varieties grown in Asia . GM rice varieties with the Xa21 gene are being field evaluated for agronomic performance and screened for environmental and health safety. 
