Plant organelles under stress
Living with oxygen is powerful and fast, but also dangerous. Mitochondria use oxygen as final electron acceptor in the respiratory chain while chloroplasts generate oxygen by splitting water in the photosynthetic light reactions. Thus, oxygen is central for energy metabolism. However, uncontrolled transfer of electrons to oxygen leads to formation of the superoxide radical and in consequence also other types of reactive oxygen species (ROS). Cells balance ROS levels by specific scavenging systems in different cell compartments.
We investigate the evolution, composition and interaction of these redox networks in different model plant species from mosses to flowering plants. To challenge the cellular redox balance, we use abiotic stresses such as cold, heat and high light, as well as mutants of different redox components. We are especially interested in how cell compartments interact and communicate their stress level, as well as in the changes of local redox capacities during the stress acclimation response.
As membranes can constitute boundaries for local redox environments, we use genetically encoded biosensors such as redox-sensitive GFP for in vivo imaging in different cell compartments.
We are associated to the RTG 2737 STRESSistance
Plant growth and fertility under ROS control
Plants and their sister group of green algae evolved elaborate systems for control of reactive oxygen species (ROS). However, they are also using controlled specific local generation of ROS to direct and signal cellular processes during plant growth and reproduction.
While all plants exhibit an alteration of generations between haploid and diploid phases (Generationswechsel), the type of plant body plans and reproduction modes has fundamentally changed between organisms such as mosses, ferns and flowering plants.
Within the DFG-funded research unit FOR5098, we investigate the innovation and coevolution underlaying plant sexual reproduction. Our project aims at revealing the ancestral functions of specific ROS generation in plant fertility and how involved proteins diversified in land plant evolution.
Species interactions under human pressure
Today's landscapes are subjected to unprecedented rates of human-induced habitat modifications resulting in a severe ecosystem transformation including the re-assemblage of biotic communities, the alteration of vegetation dynamics, habitat simplification, and the alteration of species interactions. Our research interest is aimed at (i) understanding the contemporary forces driving the facilitation or distortion of species interactions, (ii) describing the nature of these changes and (iii) exploring the multifaceted feedbacks on biodiversity, ecosystem stability and functioning in both temperate and tropical forested systems. While we work with a diversity of species, our perennial favorite organisms are the leaf-cutting ants, one of the most voracious herbivore insect (Wirth et al. 2003) and pervasive ecosystem engineer in the human-modified Neotropics (Meyer et al. 2011a, 2011b).
Recent and ongoing research activities refer to:
- Anthropogenic disturbance and the role of the key organisms for the regeneration of the Caatinga dry forest in NE-Brazil
- The proliferation of disturbance-adapted organisms and biodiversity prospects in human-modified landscapes
- Trophic interactions in tropical forest fragments
- Damage and foraging patterns of herbivorous insects
- Herbivore impacts on plant performance (from population to ecosystem level)
- Chemical ecology of food plant selection
- Leaf-cutting ants as winner species (sensu McKinney & Lockwood 1999) in human-modified ecosystems
- Ecosystem engineering via nest-mediated shifts in forest microclimate and edaphic conditions
- Consumption and herbivory levels by Atta spp.
- Microbial and chemical ecology in the leaf-cutting ant cosmos (i.e. ants, fungus garden, and microbial antagonists/mutualists)
- Effects of biochar on performance and biomass allocation of crop plants (collaboration with the National Park Hunsrück-Hochwald in the frame of the EU-funded ZENAPA („Zero Emission Nature Protection Areas“) program
- Soil contamination effects on food webs: bottom-up and top-down trophic cascades in native riparian communities including microorganisms, plants, sucking herbivores and their predators (collaboration with DFG-funded SystemLink, University of Koblenz-Landau)