【作者】 秦燕；

【导师】 杨克诚；

【作者基本信息】 四川农业大学 ， 作物遗传育种， 2007， 硕士

【摘要】 本研究以四川农业大学玉米研究所和四川农科院作物所人工合成的GP-4和GP-5群体S₂的60个单株及3个测验种为供试材料，通过SSR分子标记检测60个单株的遗传变异，并对其所配组合主要农艺、经济性状及配合力表现等做了较为全面系统的研究，结果表明：1．180个组合间除籽粒深度差异不显著外，其余性状差异均达极显著水平，表明多数性状组合间存在真实的差异（表1）。以组合间差异显著性状两季的均数进行配合力方差分析（表2），除穗行数SCA差异不显著外，其他性状GCA和SCA差异均达显著或极显著水平，表明这些性状的GCA和SCA在亲本和组合间存在真实的差异。2．60个单株GCA分析（表3）表明，不同性状GCA达显著或极显著水平的单株数有一定差异，株高、穗位高只有极少数单株达显著或极显著水平，其余性状达显著或极显著的则相对较多。经济性状中除行粒数外，其余性状的GCA表现GP-5 S₂优于GP-4 S₂。比较各性状株系内个体间GCA存在显著差异的株系数目，各性状间有较大差异，经济性状配合力的差异大于农艺性状，而经济性状中又以穗行数、行粒数、穗重和单株产量的差异较大。3．20个株系GCA分析（表4）表明，株高、穗位高GCA效应值在2个群体自交后代多数株系间差异不显著，其余各性状的GCA效应值仅在少数株系间差异不显著，因此多数经济性状GCA株系间具有较大差异。GP-4 S₂中55、57、89株系及GP-5 S2中93、105、107株系不仅产量GCA效应值较高，且多数经济性状的GCA效应值为正，可能具有较大利用潜势。3个测验种的GCA分析（表5）表明，48-2在多数农艺、经济性状上均表现较高的GCA，而9636和RPl25仅在少数农艺、经济性状上表现较高的GCA，48-2与供试群体自交后代组配具有较大的育种潜势。4．180个组合的SCA分析（表6）表明，不同性状SCA效应值达显著或极显著差异的组合个数有较大差异，株高、穗位高最少，秃尖、穗重、单株产量居中，穗长、行粒、出籽率、百粒重最多。同一性状不同群体自交后代所配组合SCA达显著或极显著差异的个数也有一定差异，但差异较小。比较单株产量对照优势大于8％的20个组合的组配方式（表7）发现，GP-5 S₂株系89、57、73和GP-5 S₂株系105、107内的个体与48-2组配获得高产组合的可能性较大。5．利用95对SSR引物对供试材料进行检测，筛选出40对扩增条带清晰，具明显多态性的引物，40对引物在2个群体S₂中共扩增出420个等位位点，每个SSR座位的等位基因数目为3～25个，平均为10.5个点，且GP-5 S₂的多态位点数、多态位点比例、基因型数、变异系数等均大于GP-4 S₂，同一位点在不同群体内自交后代的基因频率是不同的，从而导致各种基因型的种类和比例出现差异（表8）。基因平均杂合度（H）分析表明，40对引物中有27对引物的基因平均杂合度GP-5 S₂大于GP-4 S₂，且GP-5 S₂的基因平均杂合度在40对引物中的均数也大于GP-4 S₂，可见GP-5 S₂的基因杂合度大于GP-4 S₂，因此GP-5自交后代的纯合速率比GP-4慢（表9）。6．对遗传距离进行比较（表10），不同群体S₂间平均遗传距离大于群体内株系间平均遗传距离，群体内株系间平均遗传距离又远远大于株系内个体间平均遗传距离。根据遗传距离进行聚类分析（表11、图3），可将60个单株分为5个大类10个亚类，株系内3个单株均聚在一起，表明同一株系内个体间遗传差异较小。GP-4 S₂的30个单株主要分布在第Ⅰ和第Ⅲ类，而GP-5 S₂的30个单株则在5个大类中均有分布，群体GP-5 S₂的遗传变异可能较GP-4 S₂更为丰富。GP-4 S₂部分株系和GP-5 S₂部分株系聚在同一亚类，表明GP-4 S₂和GP-5 S₂的部分株系可能有相似的遗传背景。综上表明，多数性状GP-5 S₂GCA优于GP-4 S₂，分子标记检测结果也表明GP-5 S₂入选株系的遗传变异较GP-4 S₂大。群体内株系间经济性状的GCA株系间差异较大，而SSR标记检测也表明，群体内株系间的遗传差异远远大于株系内个体间的遗传差异，所以在利用群体自交选系时，应多选优良基本单株，并进行早代测定，以确定基本株配合力的优劣，从而提高选系效率。2个群体自交后代中55、57、89、93、105和107株系的产量GCA较高，多数经济性状GCA为正，可能具有较大利用价值。更多还原

【Abstract】 In the study the material, were 60 individuals from 2 synthesized com populations and 180 combinations derived form crosses to 3 testers based on an incomplete diallel disign. These materials were provided by SiChuan Agricultural University Corn Research Institute and SiChuan Academy of Agricultural sciences. The genetic variation Of the 60 individuals was evaluated by SSR primers, the GCA of 60 individuals and the SCA of 180 combinations of major agronomic economic traits were evaluated in an incomplete diallel disign. The main results were summarized as follows:1. Variance was significant in all the observed traits except for kernel depth in the 180 crosses （Table 1）. Analysis of combing ability in traits with significant variations in the two seasons showed that GCA and SCA variance was significant in traits except for Row/ear SCA （Table 2）.2. The results of 60 individuals GCA showed that the number of GCA effect significant at 0.05 or 0.01 was different in different traits, the number was much except plant height and ear height. And the GCA of GP-5 S₂ were better than GP-4 S₂ in most traits except kernels per row in economic traits （Table 3 ）. Comparisons the number of strains in which 3 individuals GCA effect were significant at 0.05 or 0.01. In economic traits the number was much more than in agronomic traits, the variations was higher in Row/ear, Kemels/ row, Ear.weight and Yield/plant.3. The results of 20 strains GCA showed that in most of the traits there was much variations among different strains in the same population except plant height and ear height （Table 4）. The strains 55,57,89 in GP-4 S₂ and 93,105,107 in GP-5 S₂ had more breeding potential because of, high field GCA effect and most positive economic traits GCA effect. In three testers, 48-2 had higher GCA effect in most agronomic and economic traits, so 48-2 had more potential crossed with GP-4 S₂ and GP-5 S₂ （Table 5）.4. The results of 180 crosses SCA showed that there were different hybrid numbers of SCA effect significant at 0.05 or 0.01 level in different traits. In the same traits there were different hybrid numbers in different S₂ of populations （Table 6）. Comparisons the 20 hybrids which were superiority over CK 8%, the individuals from the strains 89,57,73 105,107 had more possibility to obtain high field hybrids crossed with 48-2 （Table 7）.5. The genetic diversity of the 60 individuals were evaluated with 40 SSR primers, which are distributed on the 10 maize chromosomes. At the 40 SSR loci, a total of 420 alleles were detected in the 60 individuals. At each locus, 3 to 25 alleles could be detected, with an average of 10.5. The indexes including polymorphic site number, ratio of polymorphic sites and genotype number in GP-5 S₂ were all higher than those in GP-4 S₂ （Table 8）, so GP-5 S₂ was more polymorphic than GP-4 S₂. It was shown in the table 9 that the average gene heterozygosity in GP-5 S₂ was higher than that in GP-4 S₂. This result not only showed there was more abundant genetic diversity in GP-5 S₂, but also indicated that the inbred progenies of GP-5 became homozygous slower.6. The average genetic distance between GP-4 S₂ and GP-5 S₂ was 0.609, The average genetic distance among the 20 strains was 0.532,The average genetic distance among the individuals within the same strain was 0.065 （Tablel0）, So the average genetic distance between GP-4 S₂ and GP-5 S₂ was higher than that among the 20 strains, and the average genetic distance among the 20 strains was also much higher than that among the different individuals in the same strain. The 60 individuals were classified into 5 groups and 10 subgroups according to genetic distance （Table 11 and Pic 3）, the 3 individuals in a strain were classified together, it showed that the genetic difference between them was less. The 30 individuals in GP-4 S₂ most divided into theⅠandⅢgroup, the 30 individuals in GP-5 S₂ some strains from GP-4 S₂ and GP-5 S₂ were classified into the same subgroup, It indicated that these strains may have the same genetic backgrounds.It concluded that the GCA of GP-5 S₂ was better than GP-4 S₂ in most traits, and the GP-5 S₂ was more genetic variation than GP-4 S₂ by SSRs. There was much GCA variation among different strains in the same population, and the genetic variation among the 20 strains was also much higher than that among the different individuals in the same strain by SSRs. In order to improve the efficiency, when selecting inbred lines from synthetic population, the more individuals should be selected to test combing ability in early generation. The strains 55,57,89 in GP-4 S₂ and 93,105,107 in GP-5 S₂ had more breeding potential because of high field GCA effect and most positive economic traits GCA effect.更多还原