Genetic improvement of rice (Oryza Sativa l.)

Abstract

The emerging challenges of increasing global population, decreasing arable lands, and escalating threats posed by climate change exert pressure on the genetic improvement of rice to increase its yield potential in irrigated and nonirrigated lands as it is the staple food of more than three billion people. Advances in genetics and molecular biology have enabled scientists to use yield-enhancing functional genes for rice genetic improvement. Recently, SNP markers associated with major yield-enhancing functional genes have been used to develop breeding lines with 9-32% yield increase over the check variety. New methods to identify high yield-expressing genes and to transfer these genes into different elite cultivars are continuously being developed to increase rice production and productivity. Additional genetic resources have also been identified from the nearest wild relatives. Resistance genes lost during the domestication process of rice and their pyramids are being transferred into elite rice cultivars to make the future rice cultivars genetically resistant to biotic stresses and tolerant to abiotic stresses. Promising methods are being developed toward the genetic improvement of rice by pyramiding genes for yield potential as well as resistance to biotic and abiotic stresses. Significant progress has been achieved at IRRI by enriching rice grain with provitamin A (b-carotene) and bio-fortification of iron and zinc. Bioavailability of these micronutrients will provide benefit to poor rice consumers, particularly in Asia to overcome the problems of vitamin A, iron, and zinc deficiency in their diet.