Modelling and experimental analysis of the role of interacting cytosolic and vacuolar pools in shaping low temperature calcium signatures in plant cells.
A major challenge to understanding low temperature calcium signatures in plants is defining how these signatures emerge from the interactions of different molecular components that are stored in different subcellular pools of a plant cell. Here we develop an integrative model that incorporates the interactions of Ca²⁺, H⁺, K⁺, Cl⁻ and ATP in both cytosolic and vacuolar pools. Our analysis reveals how these four major ions along with ATP forms a complex network to relate the emergence of calcium signatures to other responses (e.g. pH response). Modelling results are in agreement with experimental observations for both cytosolic free calcium concentration ([Ca²⁺](c)) and pH. The model is further validated by experimentally measuring the response of [Ca²⁺](c) to six fluctuating (rather than constant) temperature profiles. We found that modelling results are in reasonable agreement with experimental observations, in particular, if the rate of reducing temperature is relatively high. In addition, we show that both calcium-induced calcium release (CICR) at the vacuolar membrane and transport of ions from the cytosolic pool to the vacuolar membrane play important roles in the interaction between cytosolic and vacuolar pools. In combination they control the amount and timing of calcium release from the vacuolar to cytosolic pool, shaping the specific calcium signature. The methodology and principles developed here establish an integrative view on the role of cytosolic and vacuolar pools in shaping calcium signatures in general, and they are universally applicable to study of the interactions of multiple subcellular pools.
Durham Centre for Crop Improvement Technology, The Integrative Cell Biology Laboratory and The Biophysical Sciences Institute, School of Biological and Biomedical Sciences, Durham University, South Road, Durham DH1 3LE, UK. Junli.liu@durham.ac.uk
Junli
J
Liu
Heather
H
Knight
Charlotte H
CH
Hurst
Marc R
MR
Knight
D000255:Adenosine Triphosphate / Q000378:metabolism; D001692:Biological Transport / Q000502:physiology; D002118:Calcium / Q000378:metabolism*; D003080:Cold Temperature; D003600:Cytosol / Q000378:metabolism*; D059828:Plant Cells / Q000378:metabolism*; D014617:Vacuoles / Q000378:metabolism*
D000255:Adenosine Triphosphate; D002118:Calcium