The Genetic Architecture of Flowering Time and Related Traits in Two Early Flowering Maize Lines

摘要

Flowering time is the major factor in determining maize (Zea mays L.) maturities. Genetic bases of flowering time and other agronomically important traits were examined in a set of interheterotic-pattern recombinant inbred lines (RILs). The RILs were developed from crossing the short-season Iodent inbred line CG60 with the short-season Stiff Stalk inbred line CG102. Recombinant inbred lines were derived through single-seed descent (S-RILs) or intermated for three generations before inbreeding (I-RILs), thereby increasing recombination. Genetic variation was high for all traits in both populations, and a large number of RILs had days to silking, days to anthesis, plant height, visual stay green, canopy reflectance, and leaf number trait values beyond the parental line ranges. Both the I-RIL and S-RIL populations had similar genetic variances and similar genetic and phenotypic correlations between traits. We conclude that although Northern Corn Belt Dents have been subjected to strong selection and drift and have diverged greatly from their source population, there is substantial cryptic variation for many traits. Our results also suggest that coupling and repulsion phase linkage blocks are not prevalent within parental genomes and that genetic correlations are caused by pleiotropic genes. Intermating may have little value in recovering extreme phenotypes for flowering time and other agronomically important traits.