Intraplant Nuclear DNA Content Variation in Diploid Nuclei of Maize (Zea maysL.)

Diploid nuclei from stem, mesocotyl, nodal root and root tip tissue of two maize hybrids were examined with respect to their DNA content. The nuclei were isolated and stained with DAPI and passed through a flow cytometer-cell sorter. The titration curve for each tissue was determined. Significant variation was observed among nuclei of different tissue types. Stem and root tips had the highest diploid nuclear DNA amounts while 2-week-old mesocotyl had the lowest diploid nuclear DNA amount. These results provide evidence that during plant development and differentiation, the amount of DNA within a diploid nucleus changes through loss of specific DNA sequences. This study also demonstrates the sensitivity of flow cytometry in detecting small intraplant variation in nuclear DNA.