- M.S., University of Bonn, Bonn, Germany
- Ph. D., University of Bonn, Bonn, Germany
- University of Karlsruhe, Karlsruhe, Germany
- Penn State University
- University of Wisconsin
Ionic Signaling Pathways in Plants
A plant’s ability to explore and adapt to the environment relies on the ability to perceive external stimuli and to translate them into appropriate developmental and growth responses. Many of these growth responses are instigated within seconds or minutes of stimulus perception, well before changes in gene expression can affect cellular physiology to reinforce and expand on these initial responses. An array of signaling and response elements must, therefore, already be positioned to rapidly coordinate external stimuli with endogenous developmental cues.
A signaling module composed of Ca2+, pH, and ROS is a central component of plant responses to a broad range of biotic and abiotic environmental stresses. Within seconds of stimulus perception, an increase in cytosolic Ca2+ levels triggers an oxidative burst and activates membrane transport processes that result in extracellular alkalinization and cytosolic acidification. Intriguingly, this signaling module also appears to be integral to the regulation of plant growth in response to endogenous cues, for example during the gravitropic curvature of roots and/or during tip growth of root hairs and pollen tubes. Similar Ca2+-dependent ROS and pH changes also are associated with tip growth in brown and green algae, suggesting that the signaling module is of ancient origin and is highly conserved. Surprisingly, however, little is known about how these signals are generated at the cellular and molecular level or how they are translated into coordinated growth responses. We are trying to elucidate the molecular mechanisms underlying this signaling module in the context of mechanical and hormone signaling.
The burgeoning advances in modern fluorescence microscopy techniques, coupled with the progress of green fluorescent protein (GFP) technologies in engineering reporters, tags, and biosensors, offer unprecedented possibilities to investigate dynamic structural and ‘activity related’ aspects of cellular signaling in vivo. Research in my laboratory uses molecular, genetic, and state-of–the-art live-cell imaging approaches to study ionic-signaling-dependent regulation of growth and development at the cellular level by monitoring stimulus-activated signaling pathways in real time in individual cells within tissues at subcellular resolution.
Monshausen, G. B., N. D. Miller, A. S. Murphy, and S. Gilroy. 2011. Dynamics of auxin-dependent Ca2+ and pH signaling in root growth revealed by integrating high-resolution imaging with automated computer vision-based analysis. Plant J. 65: 309-318.
Bloch, D., G. Monshausen, M. Singer, S. Gilroy, and S. Yalovsky. 2011. Nitrogen source interacts with ROP signalling in root hair tip-growth. Plant Cell Environ. 34: 76-88.
Richter, G. L., G. B. Monshausen, A. Krol, and S. Gilroy. 2009. Mechanical stimuli modulate lateral root organogenesis. Plant Physiol. 151: 1855-1866.
Monshausen, G.B. and S. Gilroy. 2009. The exploring root—root growth responses to local environmental conditions. Curr. Opin. Plant Biol. 12: 766-772.
Monshausen, G. B., T. N. Bibikova, M. H. Weisenseel, and S. Gilroy. 2009. Ca2+ regulates reactive oxygen species production and pH during mechanosensing in Arabidopsis roots. Plant Cell 21: 2341-2356.
Monshausen, G. B. and S. Gilroy. 2009. Feeling green: mechanosensing in plants. Trends Cell Biol. 19: 228-235.
Monshausen, G. B., M. A. Messerli, and S. Gilroy. 2008. Imaging of the Yellow Cameleon 3.6 indicator reveals that elevations in cytosolic Ca2+ follow oscillating increases in growth in root hairs of Arabidopsis thaliana. Plant Physiology 147: 1690-1698.
Haruta, M., G. B. Monshausen, S. Gilroy, and M. R. Sussman. 2008. A cytoplasmic Ca2+ functional assay for identifying and purifying endogenous cell signaling peptides in Arabidopsis seedlings: Identification of AtRALF1 peptide. Biochemistry 17: 6311-6321.
Pandey, S., G. B. Monshausen, L. Ding, and S. M. Assmann. 2008. Regulation of root-wave response by extra large and conventional G proteins in Arabidopsis thaliana. Plant J. 55: 311-322.
Monshausen, G. B., T. N. Bibikova, M. A. Messerli, C. Shi, and S. Gilroy. 2007. Oscillations in extracellular pH and reactive oxygen species modulate tip growth of Arabidopsis root hairs. Proc. Natl. Acad. Sci. USA 104: 20996-21001.