Detection of Intraspecific DNA Content Variation in<i>Zea mays</i>L. by Flow Cytometry

Flow cytometry was used to determine quantitative intraspecific DNA content variation in Zea mays. Previous studies using flow cytometry had indicated that intraspecific variation in corn was beyond the resolution of the method. The DNA content variation among corn lines observed in this study was in agreement with the amount of variation observed using microdensitometry. In order to observe intraspecific variation, the fluorochrome DAPI was shown to be superior to mithramycin. The fluorochrome: nuclei ratio was found to be critical when DAPI was used because of self absorption of the fluorescence. Flow cytometry with the fluorochrome DAPI was found to be a rapid and reliable alternative to microdensitometry in examining intraspecific DNA content variation in corn.