INTRAPLANT NUCLEAR-DNA CONTENT VARIATION IN DIPLOID NUCLEI OF MAIZE (ZEA-MAYS L)

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