Since plants have begun to colonise land, they have shaped the appearance of Earth. They account for 80% of the total biomass on Earth and virtually all life on Earth depends on their ability to perform photosynthesis. As sessile organisms, it is essential for plants to adapt their growth and development to the environment and to integrate different environmental cues, such as temperature and light. Phytochromes are photoreceptors that enable plants to sense their neighbours and to adjust germination, flowering, and transition to dormancy to the right season. Furthermore, phytochromes also have a function as thermosensors and enable plants to adapt their growth to increased ambient temperature.

We use genetics and molecular biology approaches to investigate mechanisms of phytochrome function and downstream signalling, signal integration, and light-regulation of symbiotic interactions. Using comparative studies in seed plants, ferns, and mosses, we also explore evolutionary trajectories leading from a single phytochrome in the common ancestor of land plants to diverse phytochromes in today’s plants. Overall, the goal of our research is to understand how plants adapted to environmental changes during colonisation of land, which also provides insight into mechanisms that enable plants to respond to current challenges such as climate change.

Key words:

phytochrome, light signalling, environmental signalling, photomorphogenesis, temperature sensing, signal integration, evolution, Arabidopsis thaliana, Physcomitrium patens, Ceratopteris richardii.

10 selected publications:

• Phytochrome higher order mutants reveal a complex set of light responses in the moss Physcomitrium patens.
  Yuan, J., Xu, T., and Hiltbrunner, A. (2023).
  New Phytol. n/a: n/a, doi: 10.1101/2023.02.08.527768.
• The phytochrome interacting proteins ERF55 and ERF58 repress light-induced seed germination in Arabidopsis thaliana.
  Li, Z., Sheerin, D.J., von Roepenack-Lahaye, E., Stahl, M., and Hiltbrunner, A. (2022).
  Nat. Commun. 13: 1656, doi: 10.1038/s41467-022-29315-3.
• Uncovering a novel function of the CCR4-NOT complex in phytochrome A-mediated light signalling in plants.
  Schwenk P, Sheerin DJ, Ponnu J, Staudt AM, Lesch KL, Lichtenberg E, Medzihradszky KF, Hoecker U, Klement E, Viczián A, Hiltbrunner A 2021).
  Elife. 10:e63697
• Differential phosphorylation of the N-terminal extension regulates phytochrome B signaling.
  Viczián, A., Ádám, É., Staudt, A.-M., Lambert, D., Klement, E., Romero Montepaone, S., Hiltbrunner, A., Casal, J., Schäfer, E., Nagy, F., and Klose, C. (2020).
  New Phytol. 225: 1635–1650, doi: 10.1111/nph.16243.
• COLD REGULATED 27 and 28 are targets of CONSTITUTIVELY PHOTOMORPHOGENIC 1 and negatively affect phytochrome B signalling.
  Kahle N, Sheerin DJ, Fischbach P, Koch LA, Schwenk P, Lambert D, Rodriguez R, Kerner K, Hoecker U, Zurbriggen MD, Hiltbrunner A 2020).
  Plant J. 104(4):1038-1053.
• PCH1 and PCHL promote photomorphogenesis in plants by controlling phytochrome B dark reversion.
  Enderle B, Sheerin DJ, Paik I, Kathare PK, Schwenk P, Klose C, Ulbrich MH, Huq E, Hiltbrunner A (2017).
  Nat Commun 8:2221.
• Characterization of phytochrome interacting factors from the moss Physcomitrella patens illustrates conservation of phytochrome signaling modules in land plants.
  Possart A*#, Xu T#, Paik I, Hanke S, Keim S, Hermann H-M, Wolf L, Hiss M, Becker C, Huq E, Rensing SA, Hiltbrunner A* (2017). * corresponding authors; # equally contributing first authors
  Plant Cell 29: 310-330.
• Light-activated phytochrome A and B interact with members of the SPA family to promote photomorphogenesis in Arabidopsis by reorganizing the COP1/SPA complex.
  Sheerin, D.J., Menon, C., zur Oven-Krockhaus, S., Enderle, B., Zhu, L., Johnen, P., Schleifenbaum, F., Stierhof, Y.-D., Huq, E., and Hiltbrunner, A. (2015).
  Plant Cell 27: 189–201, doi: 10.1105/tpc.114.134775.
• Molecular mechanisms and ecological function of far-red light signalling.
  Sheerin DJ, Hiltbrunner A (2017).
  Plant Cell Environ. 40(11):2509-2529.
• Phytochrome B integrates light and temperature signals in Arabidopsis.
  Legris M, Klose C, Burgie ES, Costigliolo C, Neme M, Hiltbrunner A, Wigge PA, Schäfer E, Vierstra RD, Casal JJ (2016).
  Science 354: 897-900.