Flow cytometric analyses of intraplant nuclear DNA content variation induced by sticky chromosomes

Background: In several plant species, sticky chromosomes are a consequence of genetic mutations or environmental effects on mitosis and meiosis. Sticky chromosomes result in an unequal distribution of genetic material in daughter cells. This unequal distribution is hypothesized to result in an increase in the coefficient of variation (CV) of the G1 peak of dividing cells. Methods: The G1 mutant and a nonmutant line in the same genetic background of maize (Zea mays L.) were planted in a soilless mix. A wheat (Triticum aestivum L. em thell.) line was grown in both low and high aluminum-saturated soil. Both plant species were assessed for sticky chromosomes by Feulgen-stained mitotic analysis and flow cytometric analysis of propidium iodide (PI)-stained G1 nuclei. Results: In the St₁ mutant, a significant increase in the number of abnormal anaphase figures was observed. An increase in abnormal mitotic figures was observed in wheat plants grown in aluminum soil. Using flow cytometry, an increase in the CV of the G1/G0 peak was seen in the maize mutant and in wheat grown at high levels of aluminum saturation. This increase correlated with the number of abnormal anaphase cells observed. Conclusions: Flow cytometry was sensitive enough to detect the intraplant nuclear DNA variation associated with sticky chromosomes within a plant.