The long-term goal of research in the Haswell lab is to reveal the molecular mechanisms that underlie the perception and transduction of mechanical signals in plants. Many organisms sense and respond to mechanical forces, and one way in which this can be accomplished is through the activation of mechanosensitive (MS) ion channels. Land plants provide a particularly relevant model system for the study of MS channels, as numerous MS channel activities have been identified in plant membranes, and they are implicated in a wide range of physiological processes. However, we do not know the molecular identity of the MS channels involved, nor how their activities might be regulated. To begin to gain insight into the plant mechanosensory apparatus, we have undertaken the characterization of ten Arabidopsis thaliana homologs of the bacterial mechanosensor MscS. We have discovered that plant MscS homologs are not simple safety valves, but are regulated channels with distinct and diverse roles at the organellar, cellular, and organismal level. Click here for coverage in the popular press and here for project outcomes aimed at a general audience.

*MS Channels in the Plastid Envelope

Our studies on the plastid-localized Arabidopsis MscS homologs MSL2 and MSL3 has revealed how organelles use these proteins to respond to membrane stretch, how their activity is integrated into cellular signaling networks, and how plants adjust to their absence. These results suggest that plant MscS homologs are not merely safety valves but regulated channels with multiple roles at the organellar, cellular, and organismal level.

*Role of MS Channels in Pollen Development

MscS is a non-selective mechanosensitive ion channel that is gated directly through tension in the membrane, and serves as an osmotic release valve during hypoosmotic swelling. We have been asking the question: what physiological function do homologs of Ec-MscS homologs in play in the model flowering plant Arabidopsis thaliana? We discovered that MSL8 as been repurposed to regulate osmotic forces during pollen hydration and germination.

*Tools to Watch Mechanoperception in Action

Many questions remain about mechanoperception, but we are limited by our ability to measure ion flux and membrane tension in the context of an intact plant tissue. We are developing imaging-based approaches to analyze the biophysical response of organelle membranes to osmotic stress and to measure and modulate membrane voltage and membrane tension in intact plant cells.


Contact Info

Department of Biology, Box 1137
One Brookings Drive
Saint Louis, MO  63130
Lab: McDonnell 249  314.935.9634
Liz's Office: McDonnell 221  314.935.9223

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