Elucidating cold-triggered chemoelectrical systemic signalling mechanisms and the integration of the Two Pore Channel 1 in the signalling network

• Applicant: Professor Dr. Edgar Peiter
• Subject Area: Plant Biochemistry and Biophysics ; Plant Physiology
• Term: from 2017 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 327830483

• Final Report Year: 2024

Final Report Abstract

Transient changes in cytosolic free calcium ([Ca2+]cyt) are one of the earliest responses of a plant cell upon stress perception. Not only those parts of the plant that are directly exposed to the stress show an increase in [Ca2+]cyt, but also unaffected tissues. Such “systemic” Ca2+ signals prepare the distal organs for the upcoming stress situation. The mechanisms of how such fast systemic signals propagate within the plant are incompletely understood. This project was initially aimed at elucidating mechanisms of systemic responses to cold stress and the integration of the vacuolar two pore channel 1 (TPC1). Although an involvement of TPC1 in the Ca2+ response to cold was apparent, technical and organizational matters required a re-focusing of the project to other stimuli, wounding and salinity. We identified annexin 1 as further component of the systemic Ca2+ signalling machinery. An analysis of wounding-induced systemic Ca2+ signals by different reporters showed marked differences between aequorin- and GCaMP3-based imaging. Whereas aequorin indicated an absolute requirement for TPC1, this was quantitative in GCaMP3 experiments. Furthermore, the systemic response was dependent on cation status of the plant in a TPC1-dependent manner. In contrast to leaf wounding, systemic Ca2+ signals initiated by stem wounding were not TPC1-dependent. The channel was furthermore identified as positive and negative regulator of systemic Ca2+ signals under salt and hypoosmotic stress, respectively. Extending from the studies on Arabidopsis, a comparative analysis was pursued in barley, which revealed dose- and tissue-dependent stimulus-specific Ca2+ signals that showed notable differences to the responses of Arabidopsis. In barley, systemic Ca2+ signals upon wounding propagated within the root system and along the leaf blade, but not between leaves.

Publications

• ANNEXIN1 mediates calcium‐dependent systemic defense in Arabidopsis plants upon herbivory and wounding. New Phytologist, 231(1), 243-254.
  Malabarba, Jaiana; Meents, Anja K.; Reichelt, Michael; Scholz, Sandra S.; Peiter, Edgar; Rachowka, Julia; Konopka‐Postupolska, Dorota; Wilkins, Katie A.; Davies, Julia M.; Oelmüller, Ralf & Mithöfer, Axel
  
• Comparative analysis of stress-induced calcium signals in the crop species barley and the model plant Arabidopsis thaliana. BMC Plant Biology, 22(1).
  Giridhar, Maya; Meier, Bastian; Imani, Jafargholi; Kogel, Karl-Heinz; Peiter, Edgar; Vothknecht, Ute C. & Chigri, Fatima
  
• Elucidating the diversity of systemic calcium signals evoked by abiotic and biotic stimuli. Botanik-Tagung, 28/08-01/09/2022, Bonn. Poster prize
  Raj, S.; Meier, B. & Peiter, E.
  
• Elucidating the diversity of systemic calcium signals evoked by abiotic and biotic stimuli. Plant Calcium Signalling Conference, 11-13/07/2022, Milan, Italy. Poster prize
  Raj, S.; Meier, B. & Peiter, E.
  
• Elucidating the diversity of systemic calcium signals. 36th Conference on Molecular Biology of Plants, 06-09/02/2023, Hennef. Poster prize
  Raj, S.; Meier, B. & Peiter, E.
  
• Elucidating the diversity of systemic calcium signals. 54th Annual Conference of the DGP, 04-05/10/2022, Raitenhaslach. Poster presentation
  Raj, S.; Meier, B. & Peiter, E.
  
• Elucidation of stress-induced Ca2+ signals in the crop species barley. 54th Annual Conference of the DGP, 04-05/10/2022, Raitenhaslach. Poster presentation
  Meier, B.; Giridhar, M.; Chigri, F.; Imani, J.; Kogel, K. H.; Vothknecht, U. C. & Peiter, E.
  
• Stress-induced calcium signals in the crop species barley. Botanik-Tagung, 28/08-01/09/2022, Bonn. Talk
  Meier, B. & Peiter, E.
  
• An organellar journey - mechanisms of intracellular calcium and manganese distribution in plants and crops. IBIP Seminar, CNRS/INRAE/Institut Agro/Université Montpellier, 22/06/2023, Montpellier, France. Talk
  Peiter, E.
  
• Determination of systemic calcium signals by a vacuolar cation channel. 55th Annual Conference of the German Society of Plant Nutrition (DGP), 25- 27/09/2023, Hohenheim. Poster prize
  Raj, S.; Meier, B. & Peiter, E.