Dissertation
Dissertation > Agricultural Sciences > Crop > Cereal crops > Corn ( maize )

QTL Mapping Andanalysis for Yield Traits and Related Gene Cloning of Plant Architecture Traits in Maize

Author ZhangWeiQiang
Tutor ChenYanHui
School Henan Agricultural University
Course Crop Genetics and Breeding
Keywords Corn Yield QTL Seed rate Particles deep Plant Type BR ZmLIC ZmDwarf2 Expression Analysis
CLC S513
Type Master's thesis
Year 2011
Downloads 20
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High-yielding is the eternal subject and direction in maize breeding. Our maize breeding and production practice showed that breeding and spreading of high-yielding maize hybrid varieties with resisting the high-density adversity is the important way to realize high yield constantly. The good quality and reasonable space distribution of corn plant is the primary cause of density-resistant. While maize plant with larger groups, good density-resistant, less competition among plant individual, male and female development coordination, and good fecundity are the internal mechanism of improving yield. Maize yield are consist of Shelling percentage, Kernel depth, and 100-kernel weight, which are interact and affect each other. So they are important traits of decision yield, but also important index of resisting the high-density adversity. Therefore, researches related to the gene effects and molecular genetic mechanism of yield components factors and plant type related traits has the important theoretical and practical significance to not only genetic improvement and good genes polymerization, and work out molecular breeding plans, but also select new high-yielding maize hybrid varieties in the condition of resistance high-density adversity.In this study, a set of F2:3 families were constructed deriving from the typical compact plant type inbred line Yu82 and the typical spreading plant type inbred line Shen137. QTL mapping and effect analysis for the yield relevant traits were studied using F2:3 families. ZmLIC and ZmDwarf2 were successfully cloned in maize that the genes were high homologous to OsLIC and OsDwarf with plant type of rice. The ZmLIC and ZmDwarf2 genes were preliminary detected and their function were speculated. We studied the gene express model of ZmLIC and ZmDwarf2 by RT-PCR, analyzing expression of organs at different grow stages in different inbred, trying to define the expression relationship between ZmLIC and ZmDwarf2. A full-length 35S fusion expression vector of ZmLIC was constructed, and making a sub-cellular detection research to the gene full length. The excessive expression vector of ZmLIC was constructed, and obtaining the transgenic generation plants by agro bacterium infects inflorescence method.The main results as follows:1. The genetic linkage map containing 222 simple sequence repeat (SSR) markers was constructed based on a mapping population consisting of 229 F2:3 families from the cross between Yu82 and Shen137. F2:3 families of grain-related traits of the phenotypic identification investigate in 3 locations, using composite interval mapping (CIM) for the localization of QTL. 4 grain-related traits were detected 15 QTL; including 3 QTL for shelling percentage, 3 QTL for kernel depth, and 4 QTL for 100-kernel weight, the joint contributions were 35.5%、28.1%和39.0% phenotypic variance respectively. Specially, QTL qSP1b for shelling percentage between umc1335 and umc2236 and QTL qKD1 for kernel depth between umc1508 and umc2235 were located in chromosome 1, which were explained 35.5%、28.1%和39.0% phenotypic variance respectively. The qKW9b for 100-kernel weight had a larger contributions and effect values in chromosome 9.2. ZmLIC gene was first successfully cloned by homology cloning, the ID of GeneBank is HQ619957. Sequence analysis showed that the cDNA full length was 1387bp, open reading frame was 1206bp, coding 401 amino acid. Phylogenetic tree analysis found that ZmLIC and OsLIC in rice in the same evolutionary branches, and its relative relation was most close, the homology as much as 74%. Protein structure prediction indicated that its protein contains typical CCCH - type zinc finger protein binding areas of OsLIC, which showed ZmLIC gene is the homologous genes of OsLIC gene.3. Real-time PCR analysis revealed that the trends of ZmLIC expression are accordance between Yu82 and Shen137, which showed low expression at 3-5- leaf stage, with the peak at 6-12 -leaf stages, and the expression decreased gradually from 13-leaf stage. The expression of ZmLIC is lowest in leaf pillow and lower in sheath. Yu82 was higher than Shen137 in expression except in leaf.4. The 35S fusion of corn and expression vector of ZmLIC gene was constructed, and it was instantaneous expressed in the skin of onion, which showed that ZmLIC gene has a function of qualitative check and ratify. The excessive expression vector of 1391-Shen137-ZmLIC was constructed; the gene was translated into wild type of Arabidopsis, the PCR test for positive candidate genes identified that the gene was successfully translated into Arabidopsis. 5. ZmDwarf2 gene was first successfully cloned by homology cloning, the ID of GeneBank is HQ619956. Sequence analysis showed that the cDNA full length was 1501bp, open reading frame was 1398bp, coding 465 amino acid. Phylogenetic tree analysis found that ZmDwarf2 and OsDwarf in rice in the same evolutionary branches, and its relative relation was most close, the homology as much as 84%. Protein structure prediction indicated that its protein contains typical cytochrome P450 add oxygen protein binding areas of OsDwarf, which showed ZmDwarf2 gene is the homologous genes of OsDwarf gene.6. Real-time PCR analysis revealed that the trends of ZmLIC expression are accordance between Yu82 and Shen137, which showed low expression at 3-4 leaf stage, with the peak at 8-12 leaf stages, and the expression decreased gradually from 13-leaf stage, Shen137 was higher than Yu82 in expression. In different organs, ZmDwarf2 expression highest on leaf pillow relatively in Yu82 and Shen137, and sheath lowest relatively. In different inbred, Shen137 was higher expression than Yu82 in leaf, leaf pillow, sheath, and stem tip.7. The expression relationship of two genes showed that the overall expression of ZmLIC was higher than ZmDwarf2 in the organs of Yu82; while the overall expression of ZmLIC was lower than ZmDwarf2 in leaf pillow of Shen137. The two genes interaction results showed that ZmLIC existed epitasis interaction effect to ZmDwarf2, and regulated the biosynthesis process of BR, which played a role of plant morphological built in different inbreeds.

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