Unit of Plant Molecular Cell Biology - Research

Research overview

Our research activities are mainly devoted to study cell‑biological phenomena in the context of plant‑microbe interactions. In particular, we focus on the interactions between plants and powdery‑mildew fungi, obligate biotrophic ascomycetes that cause agronomically relevant diseases (see Figure 1). One of our major interests is to unravel the cellular mechanisms of plant defence, but we are also interested in the molecular details of fungal pathogenicity.

Our lab employs a mixture of molecular biology, cell biology, biochemistry, plant genetics and fungal genomics to pursue these goals. The main plant species used in our research projects are the dicotyledonous reference species Arabidopsis thaliana and the monocotyledonous cereal barley (Hordeum vulgare). Accordingly, on the fungal side emphasis is given to powdery‑mildew species colonising barley (Blumeria hordei) and Arabidopsis (Erysiphe cruciferarum).

Current research projects

1. Host plant research
   Mechanism of mlo resistance and pleiotropic phenotypes. Loss of MLO protein function leads to broad‑spectrum resistance against powdery mildew. We aim to identify the underlying mechanism and to understand the unwanted side‑effects (pleiotropic phenotypes) that accompany mlo mutations in barley and Arabidopsis.
2. Barley – B. hordei interaction
   Cross‑kingdom communication and effector biology. We study exchange of small non‑coding RNAs (miRNA, tRNA‑/rRNA‑fragments) between barley and B. hordei, identify interacting proteins and explore the role of extracellular vesicles in their transport. In addition we investigate the effector repertoire of B. hordei and its mode of action.
3. Arabidopsis – E. cruciferarum interaction
   MLO and EXO70 interplay in focal secretion. Some isoforms of membrane‑resident MLO proteins confer resistance to powdery mildew, while EXO70 subunits belong to the exocyst complex that tethers exocytic vesicles. We discovered isoform‑specific interactions and are currently dissecting how MLO + EXO70 coordinate focal secretion.
4. Powdery mildew research
   Powdery mildew genomics. We investigate how transposable elements shape the evolution of powdery‑mildew pathogens, how they are regulated during infection and how they give rise to novel long non‑coding RNAs that may influence gene invention in B. hordei.

Useful links

A general introduction to the Arabidopsis‑powdery‑mildew interaction can be found in the Arabidopsis Book. A recent update of this chapter is available here.

Figure 1. Barley mlo mutants are broad‑spectrum resistant to powdery mildew. Left: susceptible (Mlo) genotype; Right: mlo‑resistant genotype after inoculation with Blumeria graminis f. sp. hordei (six days post‑infection).

Figure 2. Epifluorescence micrograph of a barley cell expressing a DsRED‑labelled peroxisomal protein. The bright dots mark mobile peroxisomes.

Figure 3. Cell‑autonomous complementation of mlo resistance by transient expression of an Mlo cDNA in a barley epidermal cell. The transformed cell (greenish) is colonised by the fungus, showing formation of an intracellular haustorium.