Detection of Intraspecific DNA Content Variation in Zea mays L. by Flow Cytometry

Flow cytometry was used to determine quantitative intraspecificDNA content variation in Zea mays. Previous studies using flowcytometry had indicated that intraspecific variation in cornwas beyond the resolution of the method. The DNA content variationamong corn lines observed in this study was in agreement withthe amount of variation observed using microdensitometry. Inorder to observe intraspecific variation, the fluorochrome DAPIwas shown to be superior to mithramycin. The fluorochrome: nucleiratio was found to be critical when DAPI was used because ofself absorption of the fluorescence. Flow cytometry with thefluorochrome DAPI was found to be a rapid and reliable alternativeto microdensitometry in examining intraspecific DNA contentvariation in corn. Key words: Genome size, corn (maize), Zea mays, DAPI