QTL Mapping And Analysis For Plant Type And Ear Traits In Maize

The maize has a vast range of prospects with its unique comprehensive utilization and high-added value. Plant traits are important agronomic traits related with grain yield in maize. They not only play an important role in grain yield production, but also are closely related with yield stability. In this study,two family lines (MU/S, MO/S) were respectively developed from two crosses between the corninbred SDM and two normal corn inbreds, MU6 and MO17. Two genetic maps were constructed using SSR markers. Using composite interval mapping (CIM) method, QTL associated with five plant traits were detected.The interactions of detected QTL were identified using multiple interval mapping (MIM) method according to the result of CIM method.These results will do great help in fine mapping QTL associated with plant traits and their map-based cloning, and in marker-assisted selection in maize breeding. The main results in this study were as follows:1. Totally,500 SSR primers were employed to screen polymorphism between two pairs of parents for the two crosses, including MO17 with SDM, MU6 with SDM.180 and 150 polymorphism markers were selected, respectively. The SSR markers that showed segregation distortion were excluded from the analysis. Finally,143 and 123 pairs of SSR markers were selected respectively to construct the maize genetic linkage maps with the genetic distance of 985.714 cM and 1085.807 cM (centimorgan) and an average of 6.89 cM and 8.76 cM using Mapmaker 3.0. 2.With interval mapping procedure,19 QTLs were detected for the former 5 traits.Wherein these,3,6,1,5,4 QTLs were respectively identified for Ear Length,Plant Height,No.of Rows per Ear,Ear Height and Branch No.of Tassel.and QTLs totally accounted for 23.18%,54.84%,8.37%,52%and 35.02%.3. Partial dominance effect make up 66.6% of ear length trait QTLs,so partial dominance effect play the leading role in ear length trait gene action model,secondly is over-dominance effect. Partial dominance effect make up 66.6% of plant height trait QTLs,so partial dominance effect play the leading role in plant height trait gene action model, secondly is dominance effect.For ear height trait,partial dominance effect make up 80% of all ear height trait QTLs.so partial dominance effect play the leading role in ear height trait gene action model. Partial dominance effect play the leading role in No.of rows per ear trait gene action model. Over-dominance effect and additive effect play the leading role in branch No.of tassel trait gene action model.4.With the multiple interval mapping analysis,15 epistasis QTLs was detected.4,6,5 epistasis QTLs were identified for plant heihgt.ear height and branch No.of tassel.The No.of rows per ear and ear length in epistatic effects were not detected.