How does stomatal density affect stomatal opening and closure under dynamic light?

In nature, leaves are often exposed to fluctuations in light intensity. These fluctuations directly impact on photosynthesis rate and plant water use efficiency, as stomata and photosynthesis do not react instantaneously to changes in light. Also, stomatal conductance (the capacity for CO2 flux into the leaf) is one of the major limitations of photosynthesis in fluctuating light. Stomata are microscopic pores on the leaf surface that exchange water vapour for CO2, and are dynamically regulated: for example, they open up in high light intensities and partially close in the shade.
After a transition from shade to high light, stomatal opening is slow (30-60 minutes), which reduces the diffusion of CO2 into the leaf and therefore photosynthesis. What is less well investigated is how strong the density and clustering of single stomata affect the speed of stomatal opening and closing, how neighbouring stomata affect each other, and what effects this has on water use efficiency. In this project, you will use epidermal patterning factor (epf) mutants (Arabidopsis thaliana), which have higher (and lower) stomatal density and clustering compared to the wildtype. Also, apart from performing measurements of photosynthetic gas exchange, you have the chance to work with a new, powerful microscopy technique that allows to film the movement of single stomata in real time – this could provide more insights into how single stomatal pores open and close, and how neighbouring pores affect each other. Type of research:
Performing short-term experiments using a gas exchange and chlorophyll fluorescence system (LI-6400 or LI-6800). Observing stomatal movement, using a lab-built microscopy system. Measuring stomatal density by silicone imprints and microscopy. Also, the following could be added if desired by the student: i) experimental growth treatments to further affect stomatal density and size, ii) white-light interferometry to investigate pore depth in addition to guard cell dimensions (at TU Twente), iii) performing growth experiments under controlled light intensity fluctuations.

Used skills

  • Gas exchange measurements
  • Data analysis

Interested in doing a BSc or MSc thesis at HPP? Please contact the HPP student coordinator Katharina Hanika.