Genetic Dissection of Yield Components in an Elite Maize Hybrid Using Molecular Markers
【摘要】：正 An F_(2:3) population from an elite hybrid (Zong3×87-1) in China was utilized for evaluating five yield components in two locations (Wuhan and Xiangfan, China) using a randomized complete block design. The mapping population included 266 F_(2:3) family lines. A genetic linkage map containing 150 SSR and 24 RFLP markers was constructed, spanning a total of 2531.6cM with an average interval of 14.5cM. By CIM (LOD≥2.5), 56 QTL were detected for five yield traits, among which, 19 QTL were detected simultaneously in both locations. The contributions to phenotypic variations for the single QTL varied from 3.0% to 22.1%. Additive, partial dominance, dominance and overdominance effects were identified for measured traits respectively. A greater proportion of overdominance effects were always observed for those traits that performed at higher levels of heterosis. A large number of epistasis interactions, including AA, AD/DA and DD, were detected for all the measured traits; AA often had a higher frequency in all the interaction types. There are significant correlations between genotype heterozygosity and trait performance only for the traits with higher heterosis. Regarding to yield traits, one kind of two-locus homozygotes was frequently the best genotypes opposite to another kind of two-locus homozygotes, which was the worst in all the nine genotypes in most two-locus significant interaction combinations. While double heterozygote genotype were never the best genotypes in any two-locus significant interaction combinations. It was implied that heterozygosity might not be always advantageous for trait performance although among such elite maize hybrid.