Endopolyploidy in Diploid and Tetraploid Maize (Zea mays L.)

Nuclei from different tissues such as stem, mesocotyl, nodal root and root tip of diploid and tetraploid maize were isolated, stained with propidium iodide and passed through an EPICS-751 flow-cytometer cell sorter. Variations in flow histograms were observed in different tissues. Stem tissues of both the diploid and tetraploid had two peaks representing G1 and G2 somatic nuclei. The remaining tissues in both the diploids and tetraploids exhibited three peaks. The first peak observed in these tissues represents G1 somatic nuclei of the lowest ploidy level. The second peak represent G2 somatic nuclei of the lowest ploidy level+G1 somatic nuclei of the next ploidy level. The third peak represents G2 of the higher ploidy level+G1 somatic nuclei of the next higher ploidy level. Statistically significant differences were observed between the diploid and tetraploid maize tissues with respect to nuclei distribution in the higher ploidy level peaks implying variation in the degree of endopolyploidy in the diploid and tetraploid maize. The results of this study suggest that the amount of endopolyploid observed in maize genotypes has an effect on their overall agronomic performance under the field conditions.Copyright 1993, 1999 Academic Press