Blumeria metallo-protease like effector: a zinc scavenging universal virulence factor in fungi?
Blumeria metallo-protease like effector (BEC1019) is a virulence factor for the obligate biotrophic barley powdery mildew (PM) pathogen, Blumeria graminis f. sp. hordei (Bgh)1. Silencing of BEC1019 reduced barley PM disease development and dispersion1. BEC1019 has homologues in a third of sequenced fungal genomes, including known zinc scavenging virulence factors – Aspf2 in Aspergillus fumigatus and PRA1 in Candida albicans2,3,4. These homologues share a zinc binding HRXXH domain, similar to M35 superfamily of metallo-proteases, but lack any known protease activity2,3,4. Therefore, BEC1019 homologues are potential zinc sequesters or “zincophores” with a universal virulence role in fungi.
This project aims to study the role of BEC1019 homologues in zinc sequestration and virulence of economically important wheat fungal pathogens.
We can show that the BEC1019 homologue acts as a virulence factor in Blumeria graminis f. sp. tritici (Bgt) (causing PM in wheat) but not in Fusarium graminearum (Fg) (causing Fusarium head blight). BEC1019 deletion mutants are being created in Zymoseptoria tritici (Zt), to evaluate its role in Septoria tritici blotch disease development. Also, our findings indicate that BEC1019 expression is regulated by zinc availability in Zt and by a homologue of the zinc sensitive transcription factor ZAP1 in Bgh. Therefore, the role of BEC1019 and other proteins involved in zinc sequestration and homeostasis in these fungal pathogens will be studied. We will also evaluate the role of BEC1019 in countering nutrional immunity in plants. Our ultimate goal is to discover new targets for crop protection.