The Improvement Of Wuyujing3in The Resistance To Stripe Disease And Eating Quality

Rice stripe disease (RSD) is a viral disease which seriously affects the rice production occurred in temperate and subtropical regions in East Asia. This viral disease is transmitted by the small brown plant hopper(Laodelphax striatellus Fallen). But it is not a fundermental solution by cultivation measures and chemical control methods on production. So the improvement of the resistance of the cultivars is considered to be the most economical and effective method of controlling the rice stripe disease. On the other hand, the endosperm amylose content of rice is the main factor determining the eating quality, but it is not an efficient and accurate way to screen through the traditional breeding methods. Therefore, it has many advantages and utilization values in using of MAS for breeding the rice with resistance to stripe disease and low amylose.Wuyujing3is a high yield variety in Jiangsu province. It is a medium maturity japonica rice variety which is bred in Jiangsu Wujin Rice and Wheat Breeding Farm using the combination of "79-51/Zhongdan1//Yangjing1/Zhongdan1" and validated by the Crop Variety Approval Committee of Jiangsu Province in1992. The total planting areas of Wuyujing3were more than1.5million hm2from1988to1994. It becomes one of the main cultivars in the southern coastal areas of Jiangsu Province, the regions along the Yangtze River and the north regions of the southern Yangtze River. However, the susceptible cultivar Wuyujing3had a reduction in production failure because of the outbreak and pandemic of stripe disease in Jiangsu Province, and it limited the further application of Wuyujing3. Even in this situation, because of its characteristics of high and stable yield, this varietie is still generally welcomed by famers. At the same time, Wuyuing3has a good eating quality itself, but there still has a gap compared with the "Nanjing46","Nanjing5055"and"Nanjing9108" which are well known for the excellent eating quality. And it doesn’t satisfy the people’s requirements of high eating quality currently. And the market competitiveness, the sales price and the peasants’income will be significantly enhanced by improving the eating quality of rice. So the improvement of resistance to stripe disease and eating quality of Wuyujing3has a very vital significance to the value of the quality in production.In this study, cross combination was performed using "Wuyujing3" with high-yield as the female parent and "Kantou194" as the male parent, which carried the RSD resistance gene Stv-b’and low-amylose content gene Wx-mq. In continuous backcross and self cross generations, the marker tightly linked with Stv-b’and Wx-mq was used for molecular marker assisted selection by combining with the identifications of field resistance to RSV and agronomic traits analysis. Finally,10improved rice lines carrying the disease-resistance gene and low-amylose content gene were obtained. Through the comparative experiment among lines, we studied in these improved lines of agronomic traits and quality traits, and selected the comprehensive characters similar or even superior to Wuyujing3. The main results are followings:1.10improved lines have been screened through molecular marker assisted selection and combination with field seletion. Determination of the phenotype of individuals from the10improved rice lines show that all of the10imroved rice lines have RSD resistance gene Stv-b’and low-amylose content gene Wx-mq. The result of the field resistance investigation shows that the incidence of the stripe disease of10improved lines is significantly lower than the susceptible control Wuyujing3. It shows that the resistant of the10improved rice lines has been improved obviously.2. The agronomic traits, quality traits and yield were analyzed with line comparative test method. The result shows that most traits of improved lines are similar to the control Wuyujing3and some other traits, such as amylose content, are significantly better than the control.3. The identification results of sensory evaluation indicated that the evaluating indicators(odor, appearance, fragrance, palatability and comprehensive score) of10improved lines are better than Wuyujing3. The K01、K02、K06、K07, K08、K09and K10have reached a level of significant or very significant in each indicators.4. Taken all factors into consideration, two improved lines of K02, K06and K10with better comprehensive chracters were selected.