Use of PCR-based molecular markers to identity weedy Amaranthus species

Weedy species of the genus Amaranthus, commonly referred co as pigweeds, ha ve increased in frequency and severity over the past few years. Identificat ion of these weeds is difficult because of similar morphological characteri stics among species and variation within species. Studies were initiated to develop a molecular marker identification system utilizing restriction enz yme analysis of amplified ribosomal DNA (rDNA). A set of polymerase chain r eaction (PCR) markers was developed to distinguish 10 weedy species of pigw eeds. Restriction-site variation, utilizing five endonucleases, within the internal transcribed spacers (ITS) of the rDNA allowed for the positive ide ntification of eight species and one pair of species. These markers will be useful for biological and ecological studies on the genus. Nomenclature: Amaranthus spp. AMASS.