This invention pertains to nucleic acid fragments encoding plant proteins that are homologs to the cis-prenyltransferases UPP synthase from the bacterium Micrococcus luteus or Dedol-PP synthase from yeast Saccharomyces cerevisiae. More specifically, this invention pertains to cis-prenyltransferase homologs from wheat, grape, soybean, rice, African daisy, rubber tree latex and pot marigold.