Daan Weits
Oxygen for plant development
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. Furthermore, atmospheric oxygen can be strongly limited as a result of heavy rainfall and flooding leading to severe crop losses.
Internal oxygen concentrations are therefore carefully monitored by plants using a molecular sensing mechanism, which induces adaptive responses, including fermentation, when the oxygen concentration drops (hypoxia).
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 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 to investigate oxygen sensing, and advanced fluorescence microscopy to observe plant stem cell niches and to visualize internal oxygen concentrations.