For germination on hydrophilic surfaces (e.g. glass), conidia of B. cinerea require organic nutrients such as sugars. On the plant cuticle, however, complete germination can occur also in distilled water. Therefore, both chemical and physical signals (surface hardness and hydrophobicity) are inducers of germination (Fig. 1; Fig. 2D). We have identified signal transduction components that are required for germination induction (Doehlemann et al., 2006; Schamber et al., 2010). Our current research aims at the identification of genes that are expressed early during germination and host surface penetration, and their role in these processes.

We are using GFP and mCherry as live-cell reporters to follow the infection process using fluorescence and laser scanning microscopy, and to study expression of infection-related genes in individual cells (Fig. 2A, B, C).