Dynamic Apical-Basal Enrichment of the F-Actin during Cytokinesis in Arabidopsis Cells Embedded in their Tissues

Abstract

During the life cycle of any multicellular organism, cell division contributes to the proliferation of the cell in the tissues as well as the generation of specialized cells, both necessary to form a functional organism. Therefore, the mechanisms of cell division need to be tightly regulated, as malfunctions in their control can lead to tumor formation or developmental defects. This is particularly true in land plants, where cells cannot relocate and therefore cytokinesis is key for morphogenesis. In the green lineage, cell division is executed in radically different manners than animals, with the appearance of new structures (the preprophase band (PPB), cytokinetic the cell plate and phragmoplast), and the disappearance of ancestral mechanisms (cleavage, centrosomes). While F-actin and microtubules closely co-exist to allow the orientation and the progression of the plant cell division, recent studies mainly focused on the involvement of microtubules in this key process. Here, we used our recently developed root tracking system to follow actin dynamics in dividing Arabidopsis meristematic root cells. In this study, we imaged in time and space the fluorescent-tagged F-actin reporter Lifeact together with cell division markers in dividing cells embedded in their tissues. In addition to the F-actin accumulation in the phragmoplasts, we observed and quantified a dynamic apical-basal enrichment of the F-actin during cytokinesis. The role and the possible actors responsible for F-actin dynamics during cytokinesis are discussed.

Tools for studying the cytoskeleton during plant cell division

“…Such work will also likely benefit from recent advances in long-term time-lapse acquisition with root tracking systems to capture for example the effects of pulse treatment on the overall cell cycle [87,88]. By analyzing root architecture and, at the subcellular level, cytoskeleton organization using fluorescent dyes [89], this approach allows the effect of the drug to be tracked as soon as it is administered. Monitoring of the effects of pharmacological perturbation over time can now be achieved with a high range of time points and in a quantitative manner.…”