| To develop a strong combination of wheat hybrid system with high resistance to Powdery Mildew diseases, wheats N9134 and N95175 were used as sources for resistance materials of Powdery mildew and the strong advantage of series of 'XIZA'hybrid varieties of wheat for parents. Wheat powdery mildew fungus strains from different regions in shaanxi province were collected, and vaccinated hybrid plants and their F1 offsprings were identified including resistance level, the area under the curve of plant period (AUDPC) and index (DI). Meanwhile, the SCAR markers co-separated with Pm21 gens and PmAS846 gene closely linked with the SSR markers were used as molecular markers for identification of resistance. An improved hybrid wheat breeding system with high disease resistance were successfully established and hence succeeded in maintaining the original heterosis of wheat hybrids as well as other agronomic traits including disease-resistance, which provided a novel avenue for super hybrid wheat breeding. The abtained main results were as follows:(1) Established a hybrid wheat resistant breeding improving technology system,and obtained the hybrid parent materials carrying disease-resistant genes. This technology can improve disease-resistance traits of hybrid wheat under the background of original advantages of hybrid wheat to achieve the purpose of high yield, high quality and high resistance. By using the improved technology system, we can improve a specific disease resistance combination of hybrid wheat and create strong advantage disease-resistant combinations wheat new materials,and provide a superior new wheat germplasm varieties and new ways of germplasm innovation. (2) Resistant materials N95175 and N9134 were characterized with immunity to disease at seedling and adult period. The AUDPC and DI values were both zero. Shaan 225 was used as control which was a highly susceptible variety,AUDPC and DI were higher; The recurrent parent materials Fp1,Fp2,Mp1 and Mp2 were characterized with highly susceptible varieties at seedling and adult plant period, The AUDPC and DI values were both higher, F1 generation of the recurrent parent and 9134 showed almost immune, AUDPCand DI values were very low at seedling and adult plant period,F1 generation of the recurrent parent and N95175 showed high and middle resistance to disease at seedling adult plant stage, respectively.AUDPC and DI is relatively low. and they possessed basically identical disease resistance with resistant parent, which accorded with heterosis dominance hypothesis.(3) Resistance of BC1 generation decreased significantly compared with F1.L21-1, L21-3, L21-4 and L21-6 contained specific segment of SCAR1265.BC1 generation was detected by SSR markers WMS67.L1-1,L1-2,L1-3,L1-6,L1-8,L2-1,L2-2,L3-3,L3-4,L4-1,L6-1,L6-2,L6-3,L8-1,L8-2,L8-4,L9-1,L9-3,L10-5,L10-6had the same type as N9134.24 plants were selected from 23 backcross generation lines which was consistent in phenotype and molecular marker identification,The 24 plants can be used as powdery mildew resistant materials with strong heterosis to continue to backcross.(4) SCAR1265 marker co-separated with gene Pm21 and PmAS846 closely linked with SSR markers were stable and reliable and had a significant specificity which can be used as molecular marker-assisted selection for hybrid breeding, these two molecular markers provided a solid theoretical basis and a favorable resistance means for fast identification.(5) In the assessment process there were resistance gene bands susceptible plants which indicated the expression of resistance genes may be the influence of environment and genetic background to some extent; Besides, plants showing disease-resistance did not produce molecular marks, which indicated an inaccuracy of molecular markers present, phenotypic identification combined with molecular markers was more accuracy.(6) The results abtained not only can be applied to the directional improving resistance to powdery mildew, but also can be used in improving other disease resistance.
|
PDF Full Text Request