A new meiotic abnormality in Zea mays: multiple spindles associated with abnormal cytokinesis in both divisions.

Abstract: We report here a new meiotic abnormality recorded in one plant of an inbred line of Zea mays. After an apparently normal prophase I, chromosomes did not congregate in a single metaphase plate. Bivalents remained scattered in the cytoplasm, giving rise to several spindles. Despite the occurrence of multiple spindles, meiosis I proceeded normally, forming a varied number of nuclei at telophase I. The presence of one or a few chromosomes in the nucleus was enough to induce local cytokinesis, which was evident from metaphase I. Each cell resulting from meiosis I expressed its own program and progressed through the cell cycle. Therefore, failure of chromosome congregation on a single plate also occurred at meiosis II, where further irregular cytokinesis was observed. As a consequence of the two abnormalities, polyads occurred, resulting in pollen grains of different sizes and in sterility at a frequency of up to 93.5%.