Tracking organelle movements in plant cells.

Cytoplasmic streaming is characterized by the rapid movement of organelles and other cellular components throughout the cell. In plants, the process depends on actin filaments and myosin motor proteins and plays an important role in cell growth. Detailed quantification of organelle movements can yield important insights into the dynamics of intracellular organization and its functional aspects. This quantification is hindered by a lack of knowledge of the different types of movements and generic tracking algorithms that yield erroneous output. This protocol provides a step-by-step guide to the detection and measurement of organelle motility as well as a description of additional analysis steps distinguishing undirected, diffusion-like movements from directional movements along the actin cytoskeleton.