Molecular Marker-assisted Breeding For Resistance To Rice Stripe Disease

Rice stripe disease transmitted by the small brown planthopper (SPBH, Laodelphax striatellus Fallen) is the one of the most serious viral diseases in japonica rice in China.It was detected in 1964 in China, and recently, the rice stripe become more severe, particularly in Jiangsu province. The practice of controlling the disease has indicated that the breeding of resistant cultivars is the most economically and environmentally safe method against the disease.In this study, the method of successive backcross was adopted. Zhen-Dao 88 with the resistance gene, Stvb-i, was chosen as the donor parent and Wu-Yu-Jing 3 which susceptible to the disease was chosen as the recipient and recurrent parents. Some new lines were developed by marker assisted selection (MAS) and comparison of main agrinomic characters between the new lines and recurrent parent. The major results were as follows:1,In the study reported here, the InDel markers 68.4-11-2 and 79.1-11-2, polymorphic between the resistant and susceptible parents, flanking the Stvb-i, was designed according to the locating results of the resistance gene Stv-bi reported. Using the molecular markers, we detected and selected the progeny plants with the resistant gene from the backcross and evaluated the selecting efficiency in BC2F3 population, which was 97.7%. Therefore, the markers 68.4-11-2 and 79.1-11-2 can be effectively utilized in marker-assisted breeding of resistance to the disease.2,In addition, we developed some polymorphic markers to do background selection in high backcross generations. Using the method of marker-assisted selection with together the natural resistance identification in the severe disease area, a great deal of outstanding homozygous lines with resistance to RSV was developed.3,In the cultivar comparitive experience, we identified the resistance of 30 pure lines to RSV in severe disease environment. The result is that the infection rates of all lines were obviously lower than the control, Wu-Yu-Jing 3. It indicated that the resistance gene could express in the improved lines to increase the ability of plants resistent to RSV disease.4,By means of the observation of main agrinomic characters, yield comparison and guality analyses for the pure lines with resistance to RSV, we obtained some outstanding rice lines with good quality, high yield and excellent resistance to RSV. The best line has entered the yield comparison experiment program of new cultivars in different sites of Jiangsu Province.