Submitted to: International Rice Genetics Symposium
Publication Type: Proceedings
Publication Acceptance Date: October 22, 2000
Publication Date: N/A
Interpretive Summary: Interpretive summary not required.
Technical Abstract: Application of Mendelian genetics clearly has led to many breeding advances in rice as well as other crops. In the present paper, emphasis is placed on economically important traits for which the segregation ratios can be distinguished without elaborate progeny testing or molecular markers. Four general groups of traits are reviewed: agronomic and physiological traits, ,grain quality, pest resistance, and resistance to abiotic stresses. The single most important trait has been semidwarfism, conferred by the sd1 gene. Other important agronomic and physiological traits include photoperiod sensitivity, glabrous hulls, gold hull color, and purple leaf. Among grain quality characters, amylose content is the most important factor, ranging from waxy types with essentially no amylose, temperate japonica short and medium grain types with 16-18% amylose, tropical japonica long grains with 21-24% amylose, and many indica types with amylose up to 28%. Another significant grain quality trait is aroma, whic often appears to be under simple genetic control but which is difficult to recover in high-yielding backgrounds. Breeding for pest resistance, including both diseases and insects, has been one of the most successful examples of utilization of major genes in crops, and yet is a recurring challenge. The most important disease example is blast resistance, which has been a focus of breeding efforts for decades. Exploitation of major genes for bacterial blight resistance has been more successful than for blast. Many successful cases of major gene resistance for brown plant hopper, green leafhopper, and gall midge, have been reported in the last three decades. In general, resistance to abiotic stresses has been polygenic. Exceptions have been low-temperature induced chlorosis at the