In Vitro Culture of Rice: Transformation and Regeneration of Protoplasts

Abstract

Rice (Oryza sativa L.) is the primary food source for about 40% of the people of the world (Yamada and Loh, 1984). Based upon population growth projections, rice yields must increase by over 5 million tons per year just to maintain current levels of rice consumption per person (IRRI, 1985). Because of the importance of rice production, extensive research efforts and progress have been made during the last 30 years to improve yields. Most of this research has been carried out in China, Japan, India, and at the International Rice Research Institute (IRRI) in the Philippines on the two major subspecies of O. sativa, the japonica and indica varieties. Japonica lines are grown primarily in temperate regions of the world, especially northern China and Japan. Researchers in these countries have improved the yield of these lines considerably during the past two decades. The indica varieties, which are more adapted to the humid tropics and are thus an important food source to a larger proportion of the human population, have been improved markedly at IRRI, primarily through conventional plant breeding. It is apparent that even higher performance rice cultivars will be needed in the future. Some improvements will continue through conventional breeding programs, but these programs will be most effective when coupled to the current advances in in vitro cell culture of rice and genetic engineering using the tools of cellular and molecular biology.