QTL Mapping For Grain Yield Associated Traits Using Introgression Lines In Maize

Introgression Lines(ILs)was a permanent mapping population, which was developed using advance-backcross and marker-assisted selection, which is a novel materials for quantitative trait locus (QTL) genetic analysis. Comparing with the traditional population, there were more advantages in SSILs, such as knowable genetic background and steady genetic base; the accuracy and sensitivity of QTL mapped and identified were improved; genetic effects of QTL can be exactly analyzed. The purpose of this investigation was to identify QTL (Quantitative Trait Locusi) for maize yield related traits and those introgression lines containing favorable alleles.The two maize inbred lines, QB80 and Qi319 were used as the donor parents, respectively, and the Ye478 as the recurrent parent, two introgression line populations consisting of 61 and 72 family lines were constructed by backcrossing combined with directional selection, respectively. The two introgression line populations were evaluated across 4 environments in 2 years. The QTLs for yield and related traits were detected by stepwise regression (RSTEP-LRT) using Windows QTL ICI Mapping software. The results were as follows:1. Total of 55 QTLs for 10 traits were identified in the population with QB80 as the donor, and 49 QTLs for 10 traits were identified in the population with Qi319 as the donor under four environments. Of which 18 QTLs were detected across not less than two environments. The genetic difference between QB80 and Ye478 are more than that of Qi319 and Ye478, therefore, more yield trait QTL can be detected in the population with QB80 as the donor.2. In addition, some QTL for same trait detected in different environments were located in the same chromosome regions, and those QTL for diverse traits were also located in the same or adjacent chromosome region, forming several multiple QTL-rich regions. The detected QTL-rich regions have given a subset of important chromosome regions for fine mapping and cloning of genes for yield associated traits.The less consistent QTL was detected in two populations, indicating that the two donors contain different set of favorable alleles.3. The yield associated traits of those lines containing favorable introgression segments or alleles were significantly improved, implicating those lines are available for improving of Ye478 by QTL pyramiding.