Genetic Improvement Of The Resistance To Rough Dwarf Disease In Elite Maize Inbred Lines

Maize rough dwarf disease (MRDD) is a worldwide viral disease and it lead to great reduction of maize production. Since the 1970s, MRDD has caused significant yield losses in North, Northwest, Northeast parts of China, therefore, it has become one of the most important diseases in affecting maize production. Zhengdan958 is an elite maize hybrid with the largest amount of plant area in china. However, the production of the hybrid was potentially limited since it was one of the Maize rough dwarf disease high susceptible culitivor, which posed negative impact on the multiple-region planting. Therefore it is very important to improve its resistance to the maize rough dwarf disease.X178 as the parent of another elite maize hybrids Nongda108 harbors stable resistant gene to MRDD, and the major QTL for the MRDD was located on 8.03-bin. In 2012, we evaluated the MRDD resistance of Zhengdan958 and its parents Zheng58 and Chang7-2, Nongda108 and its parents Huang C and X178 under artificial inoculation in Baoding, Hebei Province. The results showed that Zheng58, Chang7-2, Huang C and Zhengdan958 are high susceptible to MRDD, whereas, X178, Nongda108 showed stable resistance to the disease. In this study, a total of 260 BC3F2 Single Segment Introgression Lines (SSILs) derived from Zheng58 and X178 were generated. Using marker-assisted selection (MAS) method, we fond that 11 lines acquired the major QTL of resistance to MRDD. Artificial inoculation of these 11 resistant lines in the field as well as molecular marker-assisted selection and phenotypic identification,12 resistant plants were selected for downstream analysis. Offspring of these 12 individuals were further confirmed by molecular markers,9 lines harboring homozygous anti-MRDV QTL fragment were selected finally.In this study, the inbred line X178 with stable MRDD resistance as the donor, to introduce resistant homozygous fragment of the major QTL which located at 8.03bin into Zheng58. Finally, using MAS and phenotypic selection,9 MRDD resistence lines with Z58 background were identified. The MRDD resistance Z58 will help to expand the multiple regions applications of this hybrid in China.