LOKI · Low oxygen, key ingredient of the plant stem cell niche?

Oxygen (O2) is essential for efficient energy conversion by multicellular organisms, including plants. Therefore, environmental conditions where O2 is limited (hypoxia) such as during flooding stress, pose a severe threat to plant survival and can lead to death when prolonged. I recently discovered that plant stem cells of the shoot apical meristem (SAM) are embedded in a local hypoxic niche and that this condition is even important for meristem activity. This suggests that local hypoxia may play a positive role in regulating meristems, despite being harmful to other plant tissue. Safeguarding the stem cell pool of the SAM is especially important for plant fitness, since it not only produces all above ground tissue, but also specifies the germline. In this project, I will therefore challenge the paradigm of hypoxia as a solely stressful conditions and propose that local hypoxia might create a protective environment for stem cells, whereas oxygenation outside the meristem might allow growth of differentiating organs. I will address this hypothesis via three interlinked strategies. (1) Complete the development of prototype O2 biosensors, which will unlock the ability to visualize and understand the role of O2 gradients in plant tissue. (2) Employ genetic manipulation of the O2 sensing machinery to test if and how O2 gradients provide a positional cue that spatially organizes the SAM and its derived organs. (3) Investigate the role of meristem hypoxia in formation of DNA-damaging radicals from O2 metabolism and study the evolution of the hypoxic niche and its perception.Protection of meristems and differentiating organs is essential for plants to survive flooding events which are increasing in frequency due to global warming. The novel insights on how O2 levels regulate development and the tools developed in this project will therefore be fundamental to make the strides forward that are needed to face global climate change and secure crop productivity under stress