Regulation of root hair growth and orientation
Root hairs provide an excellent experimental system for studying directional growth control in plants. This is because root hairs display highly polarized growth and their location along the root surface makes them easily amenable for cell biological and genetic analyses. We currently have a collection of Arabidopsis root hair mutants from a screen of activation tagged lines that have defects in root hair development including root hairs with altered growth direction (i.e. waving and branching phenotypes). Some of these phenotypes are reminiscent of root hairs that have a disrupted cytoskeleton. Our goal is to characterize this unique collection of mutants to gain a better mechanistic understanding of polarity establishment in plants.

Cellular mechanisms underlying plant gravity responses
One research goal in our lab is to understand the cellular and molecular mechanisms underlying gravitropism in higher plants. The directional growth and subsequent developmental patterns that a plant organ exhibits in response to gravity allows for correct anchorage, nutrient and water acquisition, seedling emergence, and light absorption for photosynthesis. Despite the critical role of gravity on plant survival, the basic mechanisms underlying gravity's effects remain unresolved. Roots have been the focus of our research on gravitropism because they offer the unique advantage in that the site of gravity perception and the site of the response occur in defined, spatially distinct regions. Therefore, the phenomenon of gravitropism not only allows us to learn more about plant sensory mechanisms and cell growth but also allows us to gain insights into plant signaling and long distance transport.

Lipid dependent regulation of plant development and response to stress
We are investigating the role of a group of lipid mediators called N-acylethanolamines (NAEs) in plant growth and development. NAE is well characterized in animal systems as part of the endocannabinoid signaling pathway. Although NAEs are endogenous metabolites in plants, little is known about their function in plant physiology. We are working with the laboratory of Dr. Kent Chapman at the University of North Texas and Dr. Kirankumar Mysore on several aspects related to this project. For instance, the dramatic morphological defects induced by NAEs on Arabidopsis roots have allowed us to design strategies toward understanding the cellular and molecular basis of NAE action in plants.

Fluorescent protein sensors for in vivo plant cell imaging
To support the research goals of the lab, we have been implementing the use of green fluorescent protein (GFP) and its variants to observe cytoskeletal/organelle dynamics and for monitoring ion and hormone levels in living plant cells.

Collaborative research
Our group has also entered into a number of collaborative projects with other principal investigators at the Foundation. For example, we are working with the group of Dr. Richard Dixon to study metabolic channeling in the phenylpropanoid pathway. Our group is involved in these studies by applying quantitative fluorescence microscopy techniques such as FRET (Fluorescence resonance energy transfer) and colocalization to study protein-protein interactions.

We also work closely with Dr. Rujin Chen who is interested in the mechanisms of polar auxin transport in plants. Since auxin regulates a variety of developmental processes in plants including gravitropism we are collaborating with the Chen group in characterizing how the cytoskeleton modulates auxin transport during plant responses to gravity.

External collaborations
Our group also collaborates with the lab of Dr. Maria Harrison at the Boyce Thompson Institute for Plant Research, Cornell University. For our joint project, we are using cellular and molecular approaches to gain insight into how the cytoskeleton mediates the development of arbuscular mycorrhizal (AM) symbiosis in roots of the model legume Medicago truncatula. We are also involved in collaborative work with Dr. Jeanmarie Verchot-Lubicz at the Oklahoma State University and Dr. Richard S. Nelson on the mechanisms of virus cell-to cell movement in plants. We are particularly interested in the role of the cytoskeleton and the endomembrane system in movement of tobacco mosaic virus (TMV) and Potato virus X (PVX).