Functional analysis of the secretome of the vascular wilt pathogen Verticillium dahliae

PO-09 Functional analysis of the secretome of the vascular wilt pathogen Verticillium dahliae H. Peter van Esse Laboratory of Phytopathology, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands. Plant diseases cause severe crop losses worldwide with devastating effects on food and feed production. Vascular fungal pathogens are particularly notorious because they lack curative treatments and survive for decades in soil via persistent resting structures. The increased need to reduce the use of harmful pesticides and to develop novel control strategies requires in-depth understanding of the biology of vascular pathogens and the molecular mechanisms underlying pathogenicity and survival. The soil-borne vascular pathogen Verticillium dahliae causes wilt disease on more than 200 plant species, including economically important crops and the model plant Arabidopsis. The proteins secreted by pathogens (secretomes) generally determine the outcome of host-pathogen interactions. Bioinformatic analyses of the recently released V. dahliae genome sequence predict over 780 secreted proteins. When excluding the cell wall-degrading enzymes, 460 secretome genes are identified encoding potential effectors that may potentially govern disease establishment. To identify proteins that modulate host immunity, a screen was developed in which secretome cDNAs would be constitutively expressed in Arabidopsis and analyzed for effects on plant defense (by screening for altered susceptibility towards various pathogens). This way, in an initial pilot screen with 45 single exon candidates, two effectors have been identified that affect host immunity. These two V. dahliae effectors will be subjected to further genetic and biochemical analyses to reveal their mode of action.