| Genetic analysis of the maize plant type traits is essential for corn breeding theory, method and strategy. Excellent plant type is one of the important goals of maize hybrid breeding, which is conducive to the reasonable distribution of CO2 and the light between the leaf layers, as well as convenient for the high efficient utilization of solar energy and the increase of the net photosynthetic rate and maize production. By means of molecular biology method, the gene mapping of the maize plant type traits will promote the research on the improvement of maize plant type and provide a theoretical guidance for the corn breeding practice, which can promote corn yield and quality improvement directly or indirectly. In this study, two mapping populations Y105×Y106 (FR population) and Y114×Y115 (GY population) were constructed with parental inbred lines Y105, Y106, Y114 and Y115, and the genetic analysis and preliminary gene mapping of the maize plant type traits were completed by SSR marker technique. The main results were as follows:1. Basing on leafroll plants of each generation group, it was found that the leaf-roller trait did not accord with the Mendelian inheritance and the mode of inheritance of qualitative traits, and did not be affected with the cytoplasmic genetic and maternal effects, while it belonged to the mode of inheritance of quantitative traits controlled by several minor genes.2. Totally,1020 pairs of SSR primers were used to screen polymorphism between two pairs of parents for the two crosses, Y105 with Y106, Y114 with Y115, and 241 and 228 polymorphism markers were selected, account for 23.6% and 22.4% of the total primers respectively. Finally,212 and 193 SSR loci were selected respectively to construct the maize genetic linkage maps with the genetic distance of 1153.3cM and 1164.6cM (centimorgan) and an average of 5.44cM and 6.10 cM using Joinmap 4.0.3.75 QTLs were detected for the 16 traits in FR population with inclusive composite interval mapping procedure, which 7,7,4,3,5,5,7,6,2,6,3,6,4,5,3,2 QTLs were respectively identified for Plant Height, Ear Height, No. of Leaves above Upmost Ear, Internodes Length above Upmost Ear, Branch No.of Tassel, length of leaf, Width of Leaf, Ear Leaf Area, Second Leaf Angle Upmost Ear, Third Leaf Angle Upmost Ear, First Internodes Length Upmost Ear, Second Internodes Length Upmost Ear, Third Internodes Length Upmost Ear, Average Internodes Length, No. of Roll Leaves and Leaf Rolling Index, and QTLs totally accounted for 67.57%,52.32%,34.52%,19.93%,41.77%, 33.6%,54.33%,48.92%,48.64%,58.45%,33.64%,58.61%,33.69%,45.9%,25.21%,14.12%.4.25 QTLs were detected for the 10 traits in GY population with inclusive composite interval mapping procedure, which 2,3,1,4,1,1,2,3,3 QTLs were respectively identified for Plant Height, Ear Height, No. of Leaves above Upmost Ear, Branch No.of Tassel, length of leaf, Width of Leaf, Ear Leaf Area, Second Leaf Angle Upmost Ear, Internodes Length above Upmost Ear and Leaf margin color, and QTLs totally accounted for 17.04%,22.93%,11.50%,28.57%,7.29%,6.22%, 14.38%,28.07%,25.90%,55.26%.5.75 QTLs were detected in FR population, in which the gene action of 37 QTLs were partial dominance,22 QTLs was additive,13 QTLs was overdominance, and only 3 QTLs was dominant; 25 QTLs was detected in GY population, in which the gene action of 11 QTLs was partially dominant,7 QTLs was additive,6 QTLs was overdominance, and only one QTL is dominant. Therefore partial dominance effect and additive effect play the leading role in the Plant Type Traits QTL in this study.6. In this study, the contribution rate of 25 QTLs was greater than 10%, and 7 QTLs was greater than 15%,which showed a obvious main effect QTL, such as qRPH-7, qRWL-4, qRSecLA-1, qRThiLA-1, qRAIL-1, qRSecIL-1-2, qYLC-10, and respectively explained the phenotypic variance 26.06%,19.09%,35.36%,34.53%,16.69%,22.3%,21.8%, and the genetic length of the confidence interval of its location is 8.8cM 8.9cM,3.1cM,1.7cM,2.4cM,1.8cM,30.0cM. Therefore, it may be improve these traits and the MAS efficiency of them by fine mapping and positional cloning.7. For the traits singnificantly correlated, same QTLs of different traits were detected at the same locus on chromosome. It was presumed that pleiotropic effects or linkge of QTLs might lead to correlation between traits, and it aslo foreshows that once the traits had the significant relationships on phenotype. They might be having the same or extraordinary neighborly locus on chromosome. |
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