QTL Mapping Analysis Of Pericarp Thickness And Kernel-related Traits Of Fresh Corn

At present, the market demand of fresh corn has gradually increased with the improvement of people’s living standard, but many fresh corn varieties in the market still have more residue and poor taste. Pericaip thickness is one of the most important factors for fresh corn taste, so the research on molecular genetic mechanism of pericarp thickness has important significance to improve the quality of fresh com. This study was to investigate QTL mapping of pericarp thickness and kernel-related traits. With 209 F11 families of RILs population constructed by B73 (a thick-pericarp common maize inbred line) and SICAU1212 (a thin-pericaip waxy maize inbred line), as well as the genetic linkage map with 275 molecular markers constructed by the publised SSR and the developed Indel, QTL mapping of pericarp thickness and kernel-related traits including kernel legnth, width and thickness was conducted by two genetic models including inclusive composite interval mapping (ICIM) and composite interval mapping (CIM). The main results were as follows:1. With inclusive composite interval mapping (ICIM), QTL mapping of pericarp thickness and kernel-related traits including kernel length, width and thickness was conducted on the population of 209 F11 families and parents at 25 days after self pollination in Yunnan. Except chromosome 2,3,5,6 and 10, totally 6 QTLs of pericarp thickness and kernel-related traits for maize kernels were detected in the rest five chromosomes, which couldexplain 7.25%～18.02% ofphenotypicvariance. Especially, QTL at bin 7.03 controlled pericarp thickness and kernel length simultaneously.2. Combined with the previous studies, QTL mapping of pericarp thickness and kernel-related traits was also comparatively conducted on the population of 209 F11 families and parents at 25 days after self pollination in Wenjiang, Chongzhou and Yunnan by composite interval mapping method based on mixed linear model. Totally,17 QTLs of pericarp thickness and kernel-related traits for maize kernels were detected in chromosome 1,2,4,7,8 and 9, which could explain 0.43%～10.84% of phenotypic variance. Especially, three QTLs had good stability, which controlled pericarp thickness, kernel length and width respectively. Under joint environmental conditions, six QTLs were detected, of which could explain the highest 6.65% of phenotypic variance. Two QTLs were founded to be affected significantly by environments, controlling pericarp thickness and kernel length respectively, which could explain 2.19%～3.87% of phenotypic variance.3. A total of 7 QTLs with epistatic effects were detected in the joint environment analysis. Especially, qPT7-2 had epistatic effects with qPT8-1 and qPTl-2 simultaneously, which could be regarded as a regulator for epistasis. Moreover, qPT7-2 played a stable and major role for pericarp thickness in single and joint environment analysis, so this QTL was very important for the regulation of pericarp thickness for fresh corn, which deserved for fine mapping studies in future.In conclusion, locus independent action, interaction between locus and environment, epistatic effect among loci all played an important role for the regulation of pericarp thickness for fresh corn, which not only laid the foundation for elucidating the genetic mechanism of pericarp thickness of maize kernels, but also provided the theoretical reference for the fine mapping and map-based cloning of major QTL forpericarp thickness of maize kernels.