Saijaliisa Kangasjärvi, University of Turku, Finland
Christina Dixelius, Plant Biology
Lecture hall A241, Uppsala BioCentre, Ultuna
14:00 - 15:00
Cross-talk in light acclimation and defence reactions in plants

Light-dependent organellar pathways carry out vital functions in determining appropriate stress reactions in plants1. We have identified Protein Phosphatase 2A (PP2A) as a key component in organellar cross-talk involved in light acclimation and pathogenesis responses in Arabidopsis thaliana2. PP2A regulatory subunit B’γ (PP2A-B’γ) is required for proper growth under favorable conditions, but does not significantly modulate plant growth and development under harsh environmental stress3. Genetic, proteomic and metabolomic analysis indicate that PP2A-B’γ acts as a negative regulator of plant immunity, and controls metabolic changes and cell death elicited by intracellular ROS signals4,5. Associated with this, PP2A-B’γ interacts with and regulates metabolic enzymes and components involved in cellular signaling. The role of PP2A in the regulatory networks underlying defence responses, light acclimation and growth in plants will be discussed.



  1. Trotta, A., Konert, G., Rahikainen, M., Finazzi, G. and Kangasjärvi, S. (2014) Signalling cross-talk in light stress and immune reactions in plants. Philosophical Transactions of the Royal Society B: 369(1640):20130235.
  2. Trotta, A., Wrzaczek, M., Scharte, J., Tikkanen, M., Konert, G., Rahikainen, M., Holmström, M., Hiltunen, HM., Rips, S., Sipari, N., Mulo, P., Weis, E., von Schaewen, A., Aro, EM. and Kangasjarvi, S. (2011): Regulatory subunit B’γ of protein phosphatase 2A prevents unnecessary defense reactions under low light in Arabidopsis thaliana. Plant Physiology 56:1464-1480.
  3. Konert G, Rahikainen M, Trotta A, Durian G, Salojärvi J, Khorobrykh S, Tyystjärvi E, Kangasjärvi S. (2015) Subunits B’γ and B’ζ of protein phosphatase 2A regulate photo-oxidative stress responses and growth in Arabidopsis thaliana. Plant Cell and Environment, doi: 10.1111/pce.12575.
  4. Li S, Mhamdi A, Trotta, A., Kangasjärvi S and Noctor G (2014) The regulatory subunit B’γ of protein phosphatase 2A acts downstream of oxidative stress in the control of salicylic acid responses by peroxisomal H2O2. New Phytologist, 202(1):145-60.
  5. Konert G, Trotta A, Kouvonen P, Rahikainen M, Durian G, Blokhina O, Fagerstedt K, Muth D, Corthals GL, Kangasjärvi S. (2015) Protein phosphatase 2A (PP2A) regulatory subunit B’γ interacts with cytoplasmic ACONITASE 3 and modulates the abundance of AOX1A and AOX1D in Arabidopsis thaliana. New Phytologist 205: 1250-1263.