Daan Weits is Assistant Professor in the group Plant Ecophysiology. He is interested in the molecular oxygen sensing mechanisms that plants employ, and how they use information on the cellular oxygen concentration to direct plant development and low oxygen stress tolerance.

The oxygen-rich atmosphere of our planet is a consequence of photosynthesis carried out by phytoplankton in the oceans and land plants on Earth’s surface. However, the availability of molecular oxygen represents a double-edged sword for plants: it is essential for ATP production via mitochondrial respiration, but it also participates in the production of highly reactive molecules and competes with carbon dioxide as a substrate for the enzyme Rubisco. Internal oxygen concentrations therefore require careful homeostasis, and it is not surprising that plant cells mount up adaptive responses when they face low oxygen (hypoxia) provision. A common response to hypoxia has been identified in higher plants, including the induction of fermentation, NO metabolism and protective proteins. This so-called hypoxic response is essential for plants to survive environmental conditions in which oxygen is limited, such as flooding.

While plants can produce their own oxygen via photosynthesis, they lack an active oxygen transport mechanism, in stark contrast with animals. Therefore, non-photosynthetically active plant cells typically have a lower oxygen than the 21% oxygen rich atmosphere. For instance, in ripe fruits, seeds, and tubers, oxygen concentrations have been documented to fall below 5%. Surprisingly, low oxygen conditions have also recently been found by our group in the small meristematic niches that enclose the plant stem cells. Meristems are essential for continued growth and production of new organs, so this low oxygen level has important consequences for plant development, metabolism and stress tolerance.

In our research unit we study the role, consequence and origin of these low oxygen niches in plants, and we use this information to guide new strategies to improve hypoxia tolerance and plant development. To tackle research questions in this context, we use molecular biology techniques. Advanced fluorescence microscopy is used to observe plant stem cell niches and to visualize internal oxygen concentrations.