THE DOMINANT MEIOTIC MUTATION, MEI025, UNCOUPLES THE MICROTUBULE CYCLE FROM THE CHROMOSOME CYCLE

Microsporocytes isolated from plants expressing the dominant meiotic m utation, Mei025, were examined cytologically by immunofluorescence sta ining of microtubules and by DAPI staining of chromatin. Previously, t his mutation was shown to cause chromatin hypercondensation and aggreg ation starting at either pachytene of prophase I or at metaphase I. Th is result has been confirmed and the analysis extended to cytoskeletal organization during abnormal meiosis. We observed that, while the chr omosome cycle was blocked or delayed from further progression at metap hase I, spatial and temporal changes in microtubule distribution conti nued. This observation demonstrates that the microtubule cycle can be uncoupled from the meiotic chromosome cycle.