Stomatal BiologyDr. Michael Raissig
Plants use sunlight to turn carbon dioxide and water into the sugars we eat and the oxygen we breathe. To take up carbon dioxide from the atmosphere land plants form microscopic “breathing” pores on their leaves, which are made up of two guard cells that can open and close and are called stomata (Greek for "mouths").
Land plants have evolved different stomatal morphologies with different gas exchange efficiencies. The grasses for example recruit two lateral subsidiary cells (or "helper cells") that support the central guard cells to open and close faster. This is important for water use efficiency since open stomata not only take up CO2 but also loose water vapor.
Form, Development and Function of Plant Stomata
The Raissig Lab studies developmental, cytological and physiological aspects of different stomatal morphologies in several land plants. We use genetic approaches like mutant screens and gene editing, (time-lapse) confocal and light microscopy, and physiological methods like infrared-based, leaf-level gas exchange measurments. We use the grass model Brachypodium distachyon that features physiologically superior four-celled stomata and the “go-to” model Arabidopsis thaliana with standard two-celled stomata. Furthermore, we are currently establishing novel model systems like Kalanchoë sp. with “intermediate” stomatal forms. Kalanchoë maintains subsidiary-like cells around stomatal guard cells, but function and developmental trajectories are thus far unknown.
We hope to understand
- how subsidiary cells are formed,
- how they function to support stomatal gas exchange efficiency, and
- how subsidiary cells have evolved.
Raissig, M. T.^, Matos, J. L., Gil, M. X. A., Kornfeld, A., Bettadapur, A., Abrash, E., et al. (2017). Mobile MUTE specifies subsidiary cells to build physiologically improved grass stomata. Science, 355(6330), 1215–1218. http://doi.org/10.1126/science.aal3254
Raissig, M. T.*, Abrash, E.*, Bettadapur, A., Vogel, J. P., & Bergmann, D. C. (2016). Grasses use an alternatively wired bHLH transcription factor network to establish stomatal identity. Proc Natl Acad Sci USA, 113(29), 8326-8331. http://doi.org/10.1073/pnas.1606728113
Lindner, H.*, Raissig, M. T.*, Sailer, C., Shimosato-Asano, H., Bruggmann, R., & Grossniklaus, U. (2012). SNP-Ratio Mapping (SRM): identifying lethal alleles and mutations in complex genetic backgrounds by next-generation sequencing. Genetics, 191(4), 1381–1386. http://doi.org/10.1534/genetics.112.141341