Spatial organization and dynamics of chromosomes and microtubules during barley mitosis.

Mitosis and cytokinesis are fundamental processes through which somatic cells increase their numbers and allow plant growth and development. Here, we analyzed the organization and dynamics of mitotic chromosomes, nucleoli, and microtubules in living cells of barley root primary meristems using a series of newly developed stable fluorescent protein translational-fusion lines and time-lapse confocal microscopy. The median duration of mitosis from prophase until the end of telophase was 65.2 and 78.2 minutes until the end of cytokinesis. We showed that barley chromosomes frequently start condensation before mitotic preprophase as defined by the organization of microtubules, and maintain it even after entering into the new interphase. Furthermore, we found that the process of chromosome condensation does not finish at metaphase, but gradually continues until the end of mitosis. In summary, our study features resources for in vivo analysis of barley nuclei and chromosomes, and their dynamics during mitotic cell cycle.