Identification of stripe rust fungal effector(s) recognized by WHEAT TANDEM KINASE 1
2The Department of Evolutionary and Environmental Biology, University of Haifa, Israel
3Department of Plant Pathology, University of California, USA
Wheat stripe rust, caused by the fungal pathogen Puccinia striiformis f.sp. tritici, is one of the most devastating diseases for wheat crops. Pst is secreting effector proteins into the host plant cells via the haustoria feeding structures aiming to suppress plant immunity responses.
Yr15 is a stripe rust resistance gene that was recently cloned in our lab from wild emmer wheat. Yr15 encodes a protein composed of kinase and pseudokinase domains in tandem, designated wheat tandem kinase 1 (WTK1). According to the model developed by our team, the tandem kinase proteins are serving as decoys that interact with the pathogen effectors to counter-defend the suppression of receptor-like kinases. Therefore, while the effectors are attempting to “switch-off” the defense response controlled by receptor kinases, they actually “switch-on” a counter-offense mechanism activated by tandem kinases. Identification of Avr-Wtk1 effector will be required for future investigations of signaling as well as inter and intramolecular changes that occur in response to pathogen perception.
Based on specific criteria, we have selected 100 Pst proteins as candidates Avr-Wtk1 effectors. We are now testing different strategies for the identification of Avr-Wtk1, including protoplast cell-death assay and generation of Pst mutants using EMS. Characterization of the wheat rust effectors will open up a new venue for resistance breeding via manipulations and engineering of novel rust resistance genes in wheat.