Selecting Of Rice Restorers And Pyramiding QTLs Resistance To Sheath Blight

Sheath blight, caused by Rhizoctonia solani, is one of the most important rice diseases. Planting resistant rice varieties is a most effective way for controlling the diseases. However, there is a little advance in improving rice resistance to sheath blight due to the complex interaction between rice and the pathogen.In this study, the types of selected backcross lines from 6 random BC2F2 populations developed by cross and backcross, in which two major hybrid restorer lines Minghui86 and Shuhui527 were used as recurrent parents respectively, and Jiangxisimiao, Teqing and Mengguandamagu used as donor, were divided by the resistance to sheath blight and agronomic traits.6 resistant lines was used to pyramid QTLs, and the general combining abilities (GCA) of 16 selected resistant lines with higher level of resistance and good agronomic traits were evaluated. The results were as following:1. Resistant rice lines were selected from the backcross populations by artificial inoculation with sheath blight pathogen. Among them, the yield of 14 resistant lines were significantly higher than that of the recurrent parent, and the yield of 61 resistant lines were no significant difference, indicating that the lines resistant to sheath blight with good agronomic traits could be selected from the backcross population derived from parents with moderate resistance level.2. 6 rice introgression lines (ILs) were used to pyramid the QTLs resistant to R. solani. The resistance levels were increased when Qsb8b pyramided with Qsb8a and Qsb7c,Qsb3b pyramided with Qsb8a and Qsb7d in Shuhui527backgroud, and 34 homozygous resistant lines were identified. While the resistance levels were increased when Qsb7 was combined with Qsb3a and Qsb1a in Minghui 86 background, and 49 homozygous resistant lines were obtained.However, the resistance level of the pyramiding lines of Qsb11/ Qsb8a and Qsb11 /Qsb7d were lower than that of the lines with single QTL, indicating there was negative interaction between Qsb11 and the two loci.3. The test cross between was 16 resistant ILs and 4 sterile lines to evaluate the combing ability of the selected resistant lines. We found Gang16A and Xie A showed high GCA on resistance, and BSB10,BSB46,BSB87and SB201 had high GCA. Moreover, 4 combinations, including Xie A/BSB10,Xie A/BSB46,XieA/BSB87 and Jin23A/BSB87, exhibited both high resistance and good agronomic traits.Our results will provide elite lines resistant sheath blight and useful information for rice breeding program.