Improvement oryza sativa L.production using anther culture and molecular markers

摘要

Rice plant is annual plant, belongs to genus Oryza, family Poaceae. In tropical areas, rice can survive as a perennial. It represents the staple food for half of the world's population, particularly poor people in less developed countries. The basic chromosome number of rice is n =12. The wild rice is distributed in humid tropics. There are more than 20 species of genus Oryza, but only two species, Oryza sativa (originated in the humid tropics of South and southeast Asia) and Oryza glaberrima (originated in Niger basin in Africa) are cultivated. Farmers favor traditional cultivars that early maturated in order to save land for other crop growth and to save water, scince rice needs more irrigation water than other grain crops. The difference in grainweight and quality within a panicle is variety-dependent, and also varies with the panicle type. Grains of aromatic rice (basmati rice) emit special aroma when cooked. Basmati rice is mostly grown in the traditional areas of North and northwestern partof Indian sub-continent for many centuries. It is the oldest common progenitor for most types. Basmati rice is photosensitive, requires relatively cooler temperatures to produce better aroma. Aroma is a complex mixture of volatile compounds, approximately 114 compounds and most of these aromatic compounds found in outer layers of grains. There is a controversy about the number of genes controlled aroma. Rice varieties improvement are represented in increasing the yield potential including modification of plant type, exploitation of heterosis, increasing yield stability, and increasing the yield potential under unfavorable environments. The importance 6f biotechnology in rice improvement is highlighted and some of the techniques used, such as somaclonal variation, embryo rescue, somatic hybridization, anther culture, molecular markers in rice breeding and introduction of novel genes into rice, are outlined.