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Alice Cheung

Molecular and cell biology of male-female interaction and polarized cell growth in plant reproduction
Biochemistry & Molecular Biology Dept.
LGRT 1224
University of Massachusetts
Amherst, MA 01003

The two current major research areas in our laboratory share the common focus of dissecting the signal transduction pathways that mediate plant cell responses to external growth and developmental stimuli.

One area of our work is understanding the signaling of directional pollen tube growth in plant sexual reproduction. Pollen tubes grow in a polar fashion to transport the sperm cells over long distances within the female tissues. The pollen tube growth process is driven by the pollen cytoplasm but is modulated by signals that originate from the female tissues to nourish and guide them to the egg cell. Our efforts are to identify female signal molecules, their receptors on the pollen surface, and signalling molecules that regulate the pollen cellular machinery for growth.

Among the molecules we are working with are female proteins that stimulate and attract pollen tube growth, pollen surface receptor kinases, pollen cell membrane associated Rac-like G-proteins, their downstream effectors in the form of kinases, the actin regulatory protein cofilin and the actin cytoskeleton (the underlying cellular system that drives the pollen tube growth process), and another family of G-proteins known as Rabs that regulate vesicular transport activities, which is essential for pollen tube elongation. Our ultimate goal is to connect these molecules in a signaling pathway that links the female stimuli to the pollen cellular response.

The second area of our work is understanding the signaling of plant growth regulators. Our current focus is the signaling of auxin-mediated gene expression. Despite its importance and extensive understanding of auxin actions, little is known about how this hormone is perceived at the cell surface and transduced to the cytosol to initiate downstream signaling pathways. Our efforts thus far led to the identification of cell surface associated Rac-like G-proteins as mediators of the auxin signal to auxin-responsive genes. Our ultimate goal is to dissect the cross talk and divergence among various signaling pathways that together produce at least a subset of the highly diverse auxin response.