Project Sieberer

Plant cells in space: the influence of gravity on the organization of microtubules.
Björn Sieberer (post-doc)

Dr. Jan W. Vos (supervisor)

The cytoskeleton of plant cells is an arrangement of microtubules and actin filaments within a cell that serves to provide support to the cell’s structure and to transport components from one part of the cell to another. The cytoskeleton, which consists of protein molecules arranged into long polymer structures, plays a crucial role in the organization of the cell structure, the process of cell division and the direction of plant growth. This ultimately determines the plant's final shape and ultimately how well it functions as a complete organism. The microgravity experiments aims at identifying the role that gravity plays in the organization and dynamics of the microtubules in living plant cells grown in space.

The cytoskeleton is of interest to space researchers because it is supposed to be the gravity sensing element of cells. Very little research has thus far been aimed at the effects of gravity on the physical aspects of the cytoskeleton organization and the effect this has on cell division and cell elongation. On earth, tubulin (the protein that forms the microtubules in the cell) organizes itself into arrays of parallel microtubules in glass chambers. This organization does not occur under weightless conditions. Moreover, protoplasts, which are plant cells from which the cell wall has been discarded, cannot divide and grow into complete plants, like these cells are competent to do on earth. They do not have a functional cytoskeleton. Nevertheless, healthy plants can be grown from seed in space. The objective of the microgravity experiments is to investigate the organization and dynamics of the cytoskeleton’s microtubules under various gravity conditions in single plant cells with intact cell walls. As model system we will use tobacco BY-2 suspension cells.

Understanding how plant cells behave in the space environment under weightless conditions can provide further knowledge on the plant growth processes on Earth, and the role played by gravity. This could lead to improved agricultural processes, which in the future may provide improved crops. Furthermore, looking ahead to the future, understanding how plants grow in space can lead to controlled plant growth for consumption and life support systems for long-term human space missions. This type of research is also useful in the development of fundamental biology.