Science / Technology - Colloquium
Monday, October 5, 2009
4:00 PM-5:00 PM
Olin Hall
223
Photosynthetic organisms are the primary transducers of solar energy into bioenergy. Hence, understanding the basic molecular and cellular mechanisms underlying their growth is essential to harvest their potential for biofuels and other forms of clean and renewable energy. Plant growth and development are the result of cell growth and cell division. These two basic processes are modified and coordinated in different plants to create an immense diversity of shapes and structures. Plant cells expand by balancing their internal turgor pressure with changes in the extensible properties of their cell walls . This is accomplished by the regulated deposition of cell wall material. Once the cell reaches a certain size, or during specific developmental processes, the cell will enter mitosis and divide. Plant division is completed when a new cell wall is built to separate the two new cells.
Polarized cell expansion or "tip growth" has been extensively studied as a paradigm to understand cell expansion. Pollen tubes, root hairs, and the protonemata of ferns and mosses, grow exclusively by this type of expansion, which is achieved by focusing all the growth resources to one end of the cell. It is well established that the actin cytoskeleton plays an essential role in polarized expansion, most likely by polarizing the vesicle transport machinery via the actin-based motor myosin XI. Nevertheless, because of the large number of myosin XI genes in vascular plants, it has been difficult to determine their precise role in cell expansion. In contrast, in the moss Physcomitrella patens, there are only two myosin XI genes, which encode proteins that are 94% identical. To determine the role of myosin XI in polarized expansion, we simultaneously silenced the expression of both myosin XIs by RNA interference (RNAi). Loss of myosin XI function results in a dramatic loss of polarized expansion; plants are stunted and composed of small rounded cells. We also show that a green fluorescent protein fusion of myosin XI localizes to the site of expansion a the tip of the growing cell. Together these results indicate that myosin XI is responsible for the transport of components important for polarized expansion.
Cost: FREE
Sponsored by: WPI Physics Department, Dr. Erkan Tuzel
Suggested Audiences: College
E-mail:
tuzel@wpi.edu
Phone: 508-831-5249
Last Modified: September 29, 2009 at 9:23 AM
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