【作者】 郭莉；

【导师】 柯永培；

【作者基本信息】 四川农业大学 ， 作物遗传育种， 2012， 硕士

【摘要】 种质资源的创新及其遗传研究是育种的物质基础,通过早代选择方法提高育种效率,可以多快好省地选育出优良的玉米杂交种,对促进我国玉米生产和农村经济发展均具有十分重要的意义。本研究以玉米杂交种阿单9号的S2和S4代株系,及其用不同杂种优势群的骨干自交系为测验种配制的相应测交组合为研究材料,利用SSR分子标记技术,对不同世代株系的遗传差异及其与产量配合力和杂种优势间的相关性进行分析,以期为玉米早代株系选育和杂交组合选择提供参考。主要研究结果如下：1.S2代株系的遗传差异分析结果,用20对SSR核心引物在52个S2代株系中共检测到61个等位基因变异,每对引物分别检测到1-7个等位基因变异和1-9个基1因型，平均分别为3.1个和4.7个;株系间的遗传距离为0.038-0.481,平均值为0.176；以遗传相似系数0.76为闽值,采用类平均法(UPGMA)将52个S2代株系划分为7大类群,其中A9-22和A9-37单独聚为一类,其余株系类群或亚群与系谱来源基本一致。2.S4代株系的遗传差异分析结果,20对SSR核心引物在22个S4代株系中共检测到39个等位基因变异,每对引物分别检测到1-3个等位基因,平均1.95个,每对引物检测到的基因型数为1-3个,平均2.15个;株系间的遗传距离为0-0.362,平均为0.195；以遗传相似系数0.85为闽值,用类平均法(UPGMA)聚类,将其划分成4大类群,其聚类结果与系谱来源一致。3.株系遗传差异位点分析表明,52个S2株系间差异位点数变幅为2-37个,且来源于同一S1代的S2代株系间的差异远小于其不同来源的S2代株系间的差异；22个S4株系间差异位点数变幅为0-23,同样,来源于同一S2代的S4代株系间的位点数差异小于其不同来源的S4代株系间的差异,其中A9-5131与A9-5133之间未检测到差异,其相应的测交组合亦有相同表现,疑似有早代稳定迹象。由此可见,S：代是急剧分离世代,育种实践上应注意增加S：代株系中优良单株的选择数量；随着世代的增加,株系逐渐稳定,应多保留来源不同的S4优良株系,适当减少同一株系内的选株数量。分析发现,在S2代株系之间差异位点数较大的株系,其衍生的S4代株系之间差异也大,而S2代之间差异小的株系在相应的S4代株系间更小,表现出有加速稳定的趋势,育种上应针对性地加以利用。4.株高和穗位高差异分析表明,来源于同一S1的S2株系间其平均株高和穗位高存在显著差异,且多数S：株系内部变异幅度较大,变异系数较高,整齐度较低；来源于同一S2株系的不同S4株系间,部分株系株高差异显著,而穗位高之间均存在显著差异,同时S4代株系内株高和穗位高的变异比S2代小,表明其群体整齐度逐渐提高。5.相关性分析结果,不同测验种配制的组合,其双亲遗传距离与相应组合单株产量特殊配合力之间相关性在2个世代均不显著,与杂种优势之间的相关性亦不显著。因此,在育种实践中,不能片面追求以双亲遗传差异的大小作为亲本选配的指标。但本研究中,来源于不同优势群测验种组配的组合,其杂种优势表现存在很大差异,说明杂种优势模式的选择更加重要。更多还原

【Abstract】 The innovation of germplasm resource and its genetic research is the material basis of breeding. Improving the efficiency of breeding by the method of early generation selection can faster breed the better maize hybrid, which is significant for the further maize production and the development of rural economy. Therefore, the maize S2and S4lines derived from a basic population of Adan9, and the corresponding combinations that crossed by different testers of widely used inbred lines from different heterotic groups were selected as experimental materials to analyze genetic variation among maize S2and S4lines by using SSR makers, and the correlations of genetic variation with yield SCA and herosis performance in this study, which would provide references for the breeding of early generation lines and the combination selection. The results were as followed:1. The results of genetic variation among S2lines:A total of61alleles were detected by20pairs of core SSR primers among52S2lines,1-7alleles and1-9genotypes of each pair, average was3.1and4.7respectively. Genetic distance among the52inbred lines ranged from0.038to0.481with an average of0.176.52S2lines were classified into7distinct groups by using the UPGMA cluster method with the genetic similarity coefficient0.76as threshold, in which the A9-22and A9-37were gathered into a cluster independently, however, the other groups or subgroups were basically consisted with the available pedigree.2. The results of genetic variation among S4lines:A total of39alleles were detected by20pairs of core SSR primers among22S4lines,1-3alleles of each pair with average of1.95, and1-3genotypes of each pair with average of2.15.Genetic distance among S4lines ranged from0to0.362with an average of0.195. With the genetic similarity coefficient0.85as threshold, all of the S4lines were classified into4distinct groups by using the UPGMA cluster method. The clustering results were consistent with the groups based on the pedigree.3. Analyzing the different alleles number of genetic variation showed that No.of different alleles among52S2lines was ranged from2to37, and the difference of S2lines which derived from the same S1line was much lower than that of different one. The different allele’s number among22S4lines were ranged from0to23and the difference of S4lines which came from the same S2line was as well as lowers than that of different S2line. Of which no difference was detected between A9-5131and A9-5133, and the same as the relevant testcrosses, which was suspected as the stabilization in early generation. We suggested that S2was a rapid segerageting generation, which should be enhanced to select more excellent plants from elit S2lines in breeding practice. The lines was as stable as generation increasing, therefore, we should keep the different original S4excellent lines and decrease suitably the amount of plants selected from the same line. According to the analysis, the S4lines derived from the corresponding S2lines whose the different allele amont were higher showed the higher different amont, however, the S4lines derived from the S2lines whose different allele amont were lower showed much more lower different amont, it seems to exist an accelerated stable trend, which should be utilized pointedly in breeding program.4. Analytical results of variation of plant height and ear height indicated that average plant height and ear height showed significant difference between S2lines which derived from the same S1, the variation maglitude and variation coefficient of most of S2lines were higher, and the uniformity of those was lower. The plant height of part of S4lines derived from the S2showed significant difference, while the ear height of all S4lines showed significant difference, also the variation of plant height and ear height in S4lines were lower than those of S2, suggested that the uniformity of population improved gradually.5. The correlation analysis results indicated that no significant correlation existed in the two generations between the genetic distance of parents and effect of SCA for yield per plant of corresponding combinations combined by different tester, also no significant correlation between the genetic distance of parents and heterosis of corresponding combinations. Therefore, we could not only pursue the size of the genetic differences between parents as an indicator of parent selection in breeding practice. However, the heterosis of the combinations crossed by testers from the different heterotic groups showed a great difference in this study, suggested that the selection of the heterotic pattern was much more important.更多还原