QTL Analysis On Single Trait And Multiple Traits Using A Normal Corn×Popcorn Population

Popcorn is a special kind of corn type being used to make popcorn flake for a series pastime foodstuff. Breeding level and efficiency in popcorn is seriously restricted due to its quite few germplasm resource. With the development of molecular marker technology, high density gentetic linkage maps were constructed, quantitative trait loci (QTL) in maize have already been identified. In this research, two hundred and fifty-nine F₂ population and F_2:3 family lines, developed from a cross between a dent corn indred, Dan232, and a elite popcorn indred, N04, were developed. A high-density genetic map was constructed using SSR markers. Three popping characteristics, 9 ear-kernel traits, 4 nutritional quality of krnel, and 9 plant characters for F_2:3 population were evaluated. Data in two environments(in spring and in summer) were combined to map QTL of these traits and evaluate their effect, using composite interval mapping(CIM). The LOD threshold values were determined by 1000 times permutation test. The interactions of detected QTL were identified using multiple interval mapping (MIM) method according to the result of CIM method. The joint QTL analysis of two or three different traits were done using composite interval mapping(CIM) of multiple traits analysis, including between different popping characteristics, between different ear-kernel characters, between different nutritional quality of ear-kernel characters, and between main plant characters, and between popping characteristics and main ear-kernel traits. This was to analyze their molecular genetic mechanism and genetic correlations between different characters, and to test for linked or pleiotropic QTL controlling correlated traits. Meanwhile, previous research results in single environment were verified. The main purpose was to provide more reliable theory basis to utilize molecular marker-assisted selection, and fine map QTL and even clone them in future.The main results in this study were as follows:1. Totally, 613 SSR primers were employed to screen polymorphism between two parents, N04 and Dan232, only 193 markers(31.48%) were in co-dominant segregation. One hundred eighty-three pairs SSR markers were selected to construct a genetic linkage map of popcorn with the genetic distance of 1762.2 cM (centimorgan) and on an average of 9.63 cM using Mapmaker 3.0.2. Sixteen QTL were mapped for 3 popping characteristics by single trait analysis. Contribution of single QTL to phenotypic variation varied from 4.85% to 15.39%. Most QTL controlled different popping characteristics located at the same marker loci or in the same marker confidence intervals. Partially dominant, over-dominant and additive effects all played main funcations in the heredity of popping characteristics. A little bigger interactions existed between some detected QTL. Most QTL controlling different popping characteristics showed pleiotropy.3. Twenty-six QTL were detected for 9 ear-kernel traits using single trait...