Computational modeling and quantitative physiology reveal central parameters for brassinosteroid-regulated early cell physiological processes linked to elongation growth of the Arabidopsis root
Ruth Großeholz,
Friederike Wanke,
Leander Rohr,
Nina Glöckner,
Luiselotte Rausch,
Stefan Scholl,
Emanuele Scacchi,
Amelie-Jette Spazierer,
Lana Shabala,
Sergey Shabala,
Karin Schumacher,
Ursula Kummer,
Klaus Harter
Affiliations
Ruth Großeholz
Centre for Organismal Studies, Heidelberg University, Heidelberg, Germany; BioQuant, Heidelberg University, Heidelberg, Germany
Friederike Wanke
Center for Molecular Biology of Plants, University of Tubingen, Tübingen, Germany
Center for Molecular Biology of Plants, University of Tubingen, Tübingen, Germany
Nina Glöckner
Center for Molecular Biology of Plants, University of Tubingen, Tübingen, Germany
Luiselotte Rausch
Center for Molecular Biology of Plants, University of Tubingen, Tübingen, Germany
Stefan Scholl
Centre for Organismal Studies, Heidelberg University, Heidelberg, Germany
Emanuele Scacchi
Center for Molecular Biology of Plants, University of Tubingen, Tübingen, Germany; Department of Ecological and biological Science, Tuscia University, Viterbo, Italy
Amelie-Jette Spazierer
Center for Molecular Biology of Plants, University of Tubingen, Tübingen, Germany
Lana Shabala
Tasmanian Institute for Agriculture, University of Tasmania, Hobart, Australia
Sergey Shabala
Tasmanian Institute for Agriculture, University of Tasmania, Hobart, Australia; International Research Centre for Environmental Membrane Biology, Foshan University, Foshan, China
Brassinosteroids (BR) are key hormonal regulators of plant development. However, whereas the individual components of BR perception and signaling are well characterized experimentally, the question of how they can act and whether they are sufficient to carry out the critical function of cellular elongation remains open. Here, we combined computational modeling with quantitative cell physiology to understand the dynamics of the plasma membrane (PM)-localized BR response pathway during the initiation of cellular responses in the epidermis of the Arabidopsis root tip that are be linked to cell elongation. The model, consisting of ordinary differential equations, comprises the BR-induced hyperpolarization of the PM, the acidification of the apoplast and subsequent cell wall swelling. We demonstrate that the competence of the root epidermal cells for the BR response predominantly depends on the amount and activity of H+-ATPases in the PM. The model further predicts that an influx of cations is required to compensate for the shift of positive charges caused by the apoplastic acidification. A potassium channel was subsequently identified and experimentally characterized, fulfilling this function. Thus, we established the landscape of components and parameters for physiological processes potentially linked to cell elongation, a central process in plant development.
