| Rice(Oryza sativa L.) is the main food crop in many Asian countries. Blast(Magnaporthe oryzae B.Couch) is one of the most serious fungal disease of rice in our country, which causes serious influence on rice yield and quality. Developping broad-spectrum resistance varieties has become one of the most green economy and sustainable development ways to control the rice blast. In this study, eight cloned blast resistance genes were separately introduced into four photo-thermo-sensitive genic male sterile lines(PTGMS) by marker assisted selection(MAS). Furthermore, the broad-spectrum resistances of new versions of PTGMS were comprehensively evaluated in the natural blast disease nursery. At last, some novel blast resistance genes were detected in an advanced backcross population. This study could provide a theoretical basis and intermediate materials for breeding broad-spectrum resistance varieties. The results are as follows:1. The eight cloned blast resistance genes(Pi37, Pit, Pid3, Pi36, Pi5, pik-h, pik-m and Pigm) were respectively incorporated into four PTGMS(Y58S, Guangzhan63-4s, C815 S and HD9802S) based on MAS and backcross breeding, and some novel versions of PTGMS were obtained. Blast disease bioassay showed that six genes(Pid3, Pigm, Pi37, Pi5, Pikm and Pik-h) were resistance to leaf and neck blast, however, the other two genes(Pit and Pi36) were susceptible to leaf and neck blast in the natural blast disease nursery.2. Blast bioassay showed that new versions harboring Pid3 had the highest resistance to leaf and neck blast. The effects of other five genes varied from different genotypes and genetic backgrounds. The order of gene effects was Pid3>Pi37≥Pigm ≥Pikm≥Pi5≥Pikh>Pi36≥Pit on leaf blast resistance, and Pid3>Pi37 ≥Pigm≥Pikh≥Pi5>Pikm>Pi36≥Pit on neck blast resistance. These new versions of PTGMS with high blast resistance could be immediately used in hybrid rice breeding.3. A molecular marker linkage map was constructed using a BC3F1 backcross population from R287(elite restorer line) and Ximaxian(resistant donor). Through genome-wide quantitative trait loci(QTL) analysis of rice blast resistance in BC3F1 population under natural infection condition, 16 QTLs were detected with resistance to leaf blast at tillering stage(RT), and 13 QTLs were resistant to panicle neck blast(RN) at maturation stage. All QTLs of alleles from Ximaxian had effects of resistance.Five QTLs(q BR1, q BR2-4, q BR4-1, q BR9-1 and q BR12) located on chromosomes 1, 2, 4, 9 and 12, respectively, had major effects on resistance to leaf and neck blast. In 2014, the LOD values of these QTLs were 13.25, 5.91, 5.25, 16.3, 8.2(leaf blast) and 21.52, 8.72, 10.57, 12.55, 17.44(neck blast), explaining the phenotypic variation of 7.56%, 18.12%, 14.89%, 23.78%, 9.32%(leaf blast) and 25.77%, 21.87%, 20.73%, 23.37%, 20.73%(neck blast), respectively. At the same time, The other three QTLs(q BR2-6, q BR6 and q BR8) on chromosomes 2, 6 and 8 had minor effects on resistance to leaf blast with the LOD values of 3.14, 4, 2.86 explaining the phenotype variation of 8.64%, 2.09%, 2.02%, respectively.4. Interestingly, a broad-spectrum resistance QTL q BR3 on chromosome 3, had large effects on resistance with LOD vaulues of 18.63 and 22.77, expaining the phenotypic variation of 21.2% and 26.1% associated with the leaf and neck blast, respctivley. The allele of q BR3 from resistant donor Ximaxian could improve 2 degree of leaf blast resistsance and reduce the incidence of neck blast with 40%. Through the comparison of identified QTLs of rice blast loci, q BR-3 may be a new broad-spectrum resistance QTL, which can be used in rice blast breeding as a new gene resource. |
PDF Full Text Request