Research

We are interested in how plants sense and respond to their environment and how these signals regulate plant development. The research emphasis of the lab is to try and understand these processes at the cellular level. We combine advanced microscopy approaches such as confocal microscopy with biochemistry and molecular biology to address a wide range of biological questions. We are also extremely fortunate to have the opportunity to use the International Space Station as a tool in our work.

Current research projects

Gravity and mechanical sensing

Gravity represents the most ubiquitous and pervasive of biological signals and its perception and response (gravimorphogenesis) play critical roles in determining overall plant development and productivity. At present, the site of gravity perception in both the root and aerial parts of the plant has been defined to the tissue level and several players in the graviresponse, such as the auxin transporter systems, have been characterized. However, we still lack a cellular and molecular understanding of how gravity and touch perception occurs and how this is translated to the precise regional regulation of growth that characterizes the gravity response in plants.

We are therefore using a combination of molecular genetics, cellular imaging and morphometric/kinematic analyses to map cellular-level signaling events, such as Ca2+-dependent signals onto the growth response in wild-type and a range of hormone and gropwth-related mutants in Arabidopsis.

Anoxia
One abiotic stress that can have dramatic effects on plant survival is reduction in oxygen availability, be it from their own metabolic activities in densely packed tissues or from the vagaries of the surroundings such as soil compaction, intense microorganism activity, seasonal flooding, encasement in ice, excess rainfall, and even agriculturally practiced submergence related to cultivation or irrigation.

Surviving these conditions requires the coupling of an oxygen sensing capacity to a rapid response system that can coordinate energy and carbohydrate metabolism to: (1) deal with the impending crisis of a cellular energy deficit and (2) elicit adaptive growth responses when necessary to allow for long-term survival. With a few notable exceptions, our current understanding of this sensory/response system is incomplete, especially at the level of the cellular events that signal the adaptive response.

Therefore, we are seeking to more fully characterize the early events that trigger, coordinate and regulate plant responses to low oxygen availability.We are using a combination of computer-based imaging and molecular genetics to characterize the spatial and temporal relationship between reduced oxygen availability and, Ca2+, pH, ROS and ATP/ADP signaling in plants. We are also using bioinformatics and transcriptional profiling to select hypoxia resistant mutants.

Spaceflight
We have been incredibly lucky to be selected by NASA for a spaceflight opportunity!

Our experiment is scheduled to launch on SpaceX 2 in December 2012 and then be transferred to the International Space Station. We will be growing plants (Arabidopsis thaliana, mouse ear cress) on orbit and then freezing them. After samples have been brought back to Earth, we will use transcriptional profiling to ask how gene expression patterns are altered by growing in space.

We will be using this approach to ask if plants experience low oxygen stress during spaceflight. This is likely to occur as without gravity there is no buoyancy-driven convection to passively mix the atmosphere around oaganisms. A zone of air depleted in oxygen can therefore build up around metabolically active, intensely respiring organs such as the roots of plants. This limitation on oxygen supply can then lead to hypoxic stress. We will be using molecular markers of low oxygen stress responses to ask if the space-grown plants show a low oxygen signature. We will also be flying two Ca2+ transporter mutants that are resistant to low oxygen stress to ask if these grow more vigorously in space than wild-type plants.

Check out our mission blog for updates as we progress to launch.

Recent Publications
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