Improvement of Three-line Rice Male Sterile Lines by Molecular Design and Their Application

Rice blast and bacterial blight are the main diseases of rice production in China. Amylose content is an important evaluation indicator for rice taste quality. The precise selection of excellent disease resistance and good taste quality with molecular markers closely linked to genes and breeding of superior rice parents can effectively improve the breeding efficiency and shorten the breeding cycle. Through molecular design breeding strategy and conventional crossing and backcrossing techniques, one or more of four genes, including broad-spectrum rice blast resistance gene Pi-1、Pi-2, bacterial blight resistance geneXa23and low amylose content geneWx^b, were precisely introduced into Rongfeng B. Four CMS lines, Jifeng A, Anfeng A, Yuehe A, with good blast resistance, and Rong 3A, with good blast and bacterial blight resistance, were successively bred and technically identified in Guangdong Province. All the CMS lines had the characteristics of moderate plant type, good tilling ability, stable and complete male sterility, high stigma exsertion, high outcross rate and good combining ability. 18 hybrid rice combinations including Jifengyou 1002, Jiyou 5618, Anfengyou 5618, Yueheyou 1002, Rong 3 you 1002, etc. derived from the improved CMS lines, were developed and released for commercial production by the Crop Variety Appraisal Committee of Guangdong Province or National Crop Variety Appraisal Committee. These combinations, with high and stable yield, good riping color and strong disease resistance, have been widely used in production and made important contributions to the development of hybrid rice in South China.