Molecular Marker-Assisted Selection Of Pyramiding R-genes To Serious Dieases And Insect Pests Into Rice

Rice (Oryza sativa) is one of the most important cereal crop in the world. Rices live with a multitude of plant diseases and insect pests throughout their lives. Bacterial blight (BB) , rice blast disease, stripe stem borer (Chilo suppressalis) and brown planthopper (BPH) .which are so called "two diseases and two insects" in rice , are the major rice diseases and insect pests. The incorporation of resistance genes into cultivars is considered as the most economical and effective approach to control the diseases and pests.Resistance of CrylAc/CpTI genes to stripe stem borer has been demonstrated in transgenic rice plants expressing genes for d-endotoxins from Bacillus thuringiensis(Bt), protease inhibitors. Dominant resistance genes Xa23, Pi9 and Bph14 have a wide spectrum of resistance to BB, blast and BPH, respectively. The CrylAc/CpTI genes and three molecular markers C189, pB8and MRG2329, which are closely linked with Xa23, Pi9 and Bph14, respectively, provide an important opportunity for improving stripe stem borer, BB, blast and BPH resistance of rice by marker assisted selection (MAS). Some rice near-isogenic lines(NILs) and materials with one, two, three or four resistance genes were developed by MAS strategy. Main results are summarized as follows:1. By marker assisted backcross breeding, Xa23 Pi9 or Bph14 gene was introgressed into 15 receptor parents (12 rice restorer lines and 3 maintainer lines) respectively. The progenies harboring the resistance gene Xa23 Pi9 or Bph14 were developed by back-cross until BC₂. The near-isogenic lines (NILs) with a resistance gene (Xa23 Pi9 or Bph14) will be constructed by outcross for once, back-cross until BC₃ and selfing for twice.2. Rice NILs carrying Pi9 and Xa23 genes or CrylAc/CpTI and Bph14 genes were developed. Five homozygous lines derived from the cross...