LAZY genes required for gravity sensing
The lazy rice mutant led to the discovery of a land-plant-specific family of genes that controls the orientation of shoots with respect to the gravity vector. By our criteria, Arabidopsis thaliana possesses six LAZY genes. We have studied their expression patterns, subcellular localizations, and roles in establishing auxin gradients that create gravity-related phenotypes. We are currently investigating how LAZY proteins couple a gravity sensor to the auxin transport mechanism that reorients growth.
Example paper LAZY genes mediate the effects of gravity on auxin gradients and plant architecture

Image analysis tools for phenotyping crop plants and Arabidopsis
Our Phytomorph project creates image analysis tools for quantifying plant traits and processes to advance studies of gene function. The goal of most of our tool development tasks is a software package for the community to use on high throughput computing resources and a quantitative trait locus (QTL) map of the process the tool was developed to measure. Examples range from Arabidopsis root gravitropism to kernels packing along the maize ear. When the trait is a process such as gravitropism, the resulting QTL plot has time as a third axis, in addition to genome position and effect.
Example paper A robust, high-throughput method for computing maize ear, cob, and kernel attributes automatically from images

The role of ABCB proteins in polar auxin transport
Directional transport of the hormone auxin through tissues and organs depends on membrane proteins in the ATP-binding cassette (ABC) transporter family. We initially discovered an ABCB gene (which we called MDR1) that was induced by the anion channel blocker 5-nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB). We showed with patch-clamp electrophysiology that this protein, now called ABCB19, has NPPB-sensitive anion channel activity when expressed in human embryonic kidney cells. We are investigating the probability that auxin permeates ABCB channels, and quantifying auxin-related phenotypes in the abcb mutants.
Example paper Block of ATP-Binding Cassette B19 ion channel activity by 5-nitro-2-(3-phenylpropylamino)-benzoic acid impairs polar auxin transport and root gravitropism

Glutamate receptors in plants
Ca2+ is a messenger in various signal transduction chains. How it enters the cytoplasm of cells is typically the least well-known part of any Ca2+ signaling pathway. Our electrophysiological research on plant glutamate receptor (GLR) genes demonstrated that they encode highly selective Ca2+ channels. There are 20 GLR genes in Arabidopsis. The channels they encode are gated (triggered to open) by at least six different amino acids, depending on their subunit composition. Mutant phenotypes indicate that GLRs play roles in lateral root formation and gravitropism.
Example paper Ca2+ conduction by an amino acid-gated ion channel related to glutamate receptors