My lab has pioneered the use of an emerging model system, the moss Physcomitrella patens, to study tip growth. The ease of molecular genetic manipulation, including gene-targeting capabilities, and the abundance of tip growing cells make moss ideal for these studies. Our studies in P. patens to date have uncovered key players required for proper actin dynamics and organization. However many outstanding questions remain. For example, the molecular events that establish the site of polarization at the cell apex are unknown. Importantly the link between actin dynamics and exocytosis, that is cell growth, remains elusive. Current studies in the lab aim to address these fundamental questions.

Molecular Mechanisms Behind Plant Cell Growth How cells grow, one of the most fundamental aspects of biology, remains an open question. My research program focuses on plant cells, which unlike many other eukaryotic cells are not motile. Confined by a relatively rigid cell wall, plant cells take a wide variety of shapes within tissues of the entire plant and ultimately these shapes dictate organismal patterning. Key to plant development is the underlying architecture of individual cells, which at the molecular level is controlled by proteins of the cytoskeleton. The plant cytoskeleton consists of two filamentous networks, microtubules and actin, and their associated proteins. The actin cytoskeleton is required for a highly polarized form of growth in plant cells known as tip growth. Tip growth, although restricted to a few cell types in most plants, is essential for development in plant species ranging from algae to flowering plants. In seed plants, tip-growing pollen tubes are required for fertilization and thus propagation of the species. Root hairs are another tip-growing cell, important for absorption of water and minerals required for growth and development of the entire plant. The research in my lab focuses on understanding the molecular mechanisms underlying tip growth. These mechanisms bear upon cell development in an evolutionarily wide range of plants.