This invention relates generally to the detection of genetic differences among soybeans. More particularly, the invention relates to soybean quantitative trait loci (QTL) for tolerance or sensitivity to HPPD-inhibitor herbicides, such as mesotrione and isoxazole herbicides, to soybean plants possessing these QTLs, which map to a novel chromosomal region, and to genetic markers that are indicative of phenotypes associated with tolerance, improved tolerance, susceptibility, or increased susceptibility. Methods and compositions for use of these markers in genotyping of soybean and selection are also disclosed, as are methods and compositions for use of these markers in selection and use of herbicides for weed control. Also disclosed are isolated polynucleotides and polypeptides relating to such tolerance or sensitivity and methods of introgres sing such tolerance into a plant by breeding or transgenically or by a combination thereof. Plant cells, plants, and seeds produced are also provided.