Functional characterization of a calcium-permeable cation channel in plants
Final Report Abstract
Although the biophysical characteristics of the vacuolar cation channel TPC1 have been studied extensively in the past, its functioning in planta and in particular its contribution to the generation of cytosolic Ca2+ signals are still matters of debate. In this project, we aimed to further elucidate the role of this channel in stimulus responses and to characterize the circumstances under which it may be required in the generation of [Ca2+]cyt signals. For this purpose, we used aequorin- and Yellow Cameleon-based techniques to measure global (whole-seedling) as well as cell-specific (guard cell) [Ca2+]cyt responses, respectively. Most of the applied stimuli, including various abiotic and biotic stresses, did not indicate a requirement of TPC1 for the generation of Ca 2+ signals at low or high availability of external Ca2+. In contrast, using photon imaging equipment, we found TPC1 to be required for a systemic Ca2+ response after leaf wounding. In addition, the response to the phytohormone gibberellin was altered in a TPC1 mutant, suggesting an involvement of TPC1 in hormonal signalling. Such a role was supported by germination experiments, in which inhibitor responses were altered in the mutant. To analyse the regulation of TPC1, putative phosphorylation sites were mutated, and the mutated gene was introduced into a tpc1 knockout mutant. The mutated proteins localized to the tonoplast, allowing their electrophysiological analysis.
Publications
- (2012) The plant vacuolar Two Pore Channel 1: Regulator of cation homeostasis or generator of calcium signals? International Workshop and Meeting of the German Society of Plant Nutrition, 5-8 September 2012, Bonn, Germany
Maaß, J.-P., Beyer, A., Peiter-Volk, T., Thor, K., Peiter, E.
- (2014) The Two Pore Channel 1 (AtTPC1) in hormone networks operating during seed germination. Plant Nutrition 2014: International Conference of the German Society of Plant Nutrition, 10-12 September 2014, Halle (Saale), Germany
Maaß, J.-P., Peiter-Volk, T., Bischoff, L., Peiter, E.
