【作者】 韩继超；

【导师】 肖炎农；

【作者基本信息】 华中农业大学 ， 植物病理学， 2009， 硕士

【摘要】 玉米大斑病和丝黑穗病都是由真菌所引起的病害,它们的流行常给玉米生产和经济的发展造成严重的损失。培育抗病品种是防治玉米大斑病和丝黑穗病危害的最经济有效途径,而抗病育种的成效取决于对抗源和抗性遗传机制的认识。目前,对玉米大斑病和丝黑穗病的症状、病原菌种、侵染循环以及流行规律等都研究得相对比较清楚,但对玉米抗大斑病和丝黑穗病QTL的精细定位以及克隆研究还很缺乏。本研究在前人研究基础上,利用对玉米大斑病和丝黑穗病表现明显抗性差异的自交系Mo17（抗病）和黄早四（感病）为试验材料,采用分子标记辅助选择方法,通过回交转育,并结合抗大斑病和丝黑穗病表型鉴定,获得了玉米抗大斑病和抗丝黑穗病的近等基因系,主要研究结果如下:玉米抗大斑病抗病近等基因系分子标记辅助选择:1.参照前人已定位的5个抗大斑病QTL的SSR标记,对BC₃F₂群体（3000株）进行分子标记前景选择,获得了含有供体（Mo17）抗大斑病QTL分子标记的植株305株。2.在这5个已定位的QTL两侧,选取118个SSR标记在亲本Mo17和黄早四中进行筛选,最终筛选出8个在亲本间具有多态性的标记,其中有6个多态性SSR标记分布在第二条染色体上,分别是:bnlg1327、umc1422、umc1518、bnlg1064、bnlg1138、umc1736;有2个多态性标记分布在第八条染色体上,分别是:umc1359、bnlg1863。利用这8个SSR标记对已筛选出的305株中选单株进行检测,结果有42株在目标区段与供体亲本（Mo17）带型相同。3.用均匀分布在全基因组且多态性好的124个SSR标记对前景选择后获得的42株中选单株进行背景选择。结果所中选的42份材料中最高遗传背景恢复率为95.86%,最低恢复率为85.4%,其中有13株的遗传背景恢复率达到89%以上,可以作为玉米抗大斑病近等基因系使用。4.抗玉米大斑病的近等基因系的病级比轮回亲本黄早四的病级明显降低。由此可以说明当第二条染色体上的3个QTL和第八条染色体上的2个QTL存在时,可降低病级。玉米抗丝黑穗抗病近等基因系分子标记辅助选择:1.选用与抗病QTL连锁标记phi099对S1代31个株系进行抗性基因检测。结果表明所有单株均带有标记phi099连锁的抗病QTL。2.用均匀分布在全基因组且多态性较好的55个SSR标记对S1代31个株系进行背景选择。结果S1代的31个株系中恢复率最高可达90.4%,恢复率最低的为71.8%,31个株系的平均背景恢复率为80.5%。有3份材料的背景恢复率达到85%以上,分别是:HS195-1为85.4%;HS195-20为90.4%;HS140-4为87.2%。更多还原

【Abstract】 Northern corn leaf blight（NCLB） and head smut in maize,caused by fungi,have been the prevalent diseases in the world,which can cause heavy losses in corn production.Developing disease resistant variety is the most economic and efficient measure to control northern corn leaf blight and head smut in maize.The resistance breeding is based on the deep understanding of genetics of resistance.So far,symptoms,pathogens and epidemics of these diseases have been studied deeply,but studies about mapping and cloning of resistance genes for these diseases are still not comprehensive.In this study, based on the research of predecessors,near-isogenic lines to northern corn leaf blight and head smut of maize are obtained by the way of molecular marker-assisted selection and backcross breeding,which used two inbred lines Mo17（resistant） and Huangzao 4 （susceptible） as parents.The main results are as follows:The molecular marker-assisted selection of resistance near-isogenic lines to NCLB1.Based on 5 major QTLs that were mapped before,305 individuals that had the same genotype as the donor（Mo17） were selected after the foreground selection in the BC₃F₂ population（3000 individuals）.2.118 pairs of SSR primers were screened polymorphisms in the 5 QTL locations.The eight polymorphic markers have been found on both sides,including 6 polymorphic markers such as bnlg1327,umc1422,umc1518,bnlg1064,bnlg1138 and umc1736 on chromosome 2 and 2 polymorphic markers,umc1359 and bnlg1863 on chromosome 8. Using these 8 markers selecting in 305 individuals,42 of them have the similar genotype with the donor（Mo 17）.3.With 124 polymorphic SSR markers for the background selection of the chosen 42 individuals after foreground selection,42 individuals of 305 individuals have the higher recovery rate,which ranged from 85.4 percent to 95.86 percent.The restoration rates of 13 individuals of them are higher than 89 percent.4.The disease indexes of near-isogenic lines of disease resistance to NCLB in maize lower than the recurrent parent Huangzao 4.It was concluded that the three main-effect QTLs in the chromosome 2 and two QTLs in the chromosome 8 could reduce the disease index.The molecular marker-assisted selection of resistance near-isogenie lines to head smut of maize1.Resistance genes were detected in the 31 individuals of S1 generation using the phi099 linked to resistant QTLs.The result showed that all of them contained the phi099.2.With 55 polymorphic SSR markers for the background selection of the chosen 31 individuals of S1 generation,31 individuals have the higher recovery rate,90.4 percent in maximum and 71.8 percent in minimum.The average restoration rate of 31 individuals are 80.5 percent,the three of them are higher than 85 percent percent.They were HS195-1 for 85.4 percent,HS195-20 for 90.4 percent and HS140-4 for 87.2 percent.更多还原