Photorespiration

Plants produce oxygen as a by-product of photosynthetic light reactions, but they don't like it very much themselves. This is because oxygen triggers photorespiration, an ancient process inherited from the evolution of photosynthesis in bacteria that lived more than three billion years ago in the still oxygen-free Precambrian ocean.

A high enough oxygen concentration in the atmosphere eventually allowed evolution of animals. However, oxygen also binds to the same enzyme, Rubisco, which is also responsible for the photosynthetic fixation of carbon dioxide. This binding of oxygen to Rubisco inhibits carbon dioxide fixation and leads to the synthesis of large amounts of phosphoglycolate.

In order to survive in the now 21% oxygen-containing atmosphere, plants need to convert this compound into more useful products. This is achieved by the photorespiratory cycle, which was one of the most important metabolic adaptations during the evolution of land plants.

The major focus of our work is twofold:

First, we want to better understand the metabolic system that allows plants to thrive in an oxygen-containing atmosphere.

Second, we also want to know how related processes work in photosynthetic bacteria.

Eventually, we would wish to use this combined knowledge for improving the growth of food and energy plants.

C4 Photosynthesis

The photorespiratory cycle is also related to the evolution of C4 plants. Such plants concentrate carbon dioxide by the so-called C4 cycle within specific cells of the leaf, the bundle-sheath. This reduces photorespiration and improves the water-use-efficiency.

We want to understand how photorespiratory processes contributed to the evolution of C4 plants.

Salt Stress Physiology

We are also interested in the adaptation of plants to salty soils. To improve plant growth and harvests on such soils, we aim to identify and possibly transfer cyanobacterial salt tolerance systems to higher plants.

Cyanobacteria are the remote ancestors of chloroplasts. They have an evolutionary history of more than three billion years and are well adapted to a variety of very different including salty habitats.

Our major target for transfer to plants is the biosynthetic system for glucosyl glycerol, a compatible solute that protects cyanobacteria from salt stress.