Mapping QTLs and Epistasis for Plant Type Traits in Maize Under Two Nitrogen Levels

A RIL population consisting of 239 families derived from the cross of Mo17×Huangzaosi and their parents,was used to construct the molecular marker linkage map and detect QTLs relevant to the traits of plant type of maize(Zea mays L.) under two N-levels. Employing nitrogen by 300 kg/ha and no nitrogen was defined as the high and low N-level correspondingly in the experiment. QTLs mapping was conducted by the software QTL mapper 1-6. Under different N-levels, six traits related to plant type including plant height, ear position, leaves per plant, and leaf length, width, leaf area at ear position were measured, respectively. Nineteen QTLs with additive effects and fourteen QTL with epistatic effects in total were located on the genome of maize, in which only one QTL with additive effects is related to plant height. There are three QTL with additive effects and three QTL with epistatic effects for ear position, four QTL with additive effects and three QTL with epistatic effects for leaf number per plant, four QTL with additive effects and three QTL with epistatic effects for length of ear leaf, four QTLs with additive effects and three QTL with epistatic effects for width of ear leaf, five QTL with additive effects and two QTL with epistatic effects for leaf area at ear position, respectively. With these results the probability, strategy, and methods of markers assisted selection in maize germplasm improvement were discussed.