The Molecular Basis Behind the “Silver Bullet”: mlo-based Powdery Mildew Resistance
J. MILLER (1), N. Clay (1) (1) Yale University, U.S.A.

Since the discovery of mlo-based powdery mildew resistance in the barley 40 years ago, this broad spectrum non-host resistance has remained effective in agriculture and is conserved for other plant species such as Arabidopsis against powdery mildew. Arabidopsis Mildew locus O (MLO)2/6/12 are plasma membrane-localized heptahelical proteins involved in powdery mildew pathogenesis, but the molecular basis of their function remains unknown. The MLO proteins are reminiscent of animal G-protein coupled receptors (GPCRs), but have been shown to not interact with the canonical heterotrimeric G proteins, Gα1, Gβ1, Gγ1, and Gγ2, all of which are involved in pattern recognition receptor (PRR)-mediated plant immunity. Recent discovery of non-canonical classes of G-proteins have increased the number of potential heterotrimeric combinations six-fold. Here, we show that some of these non-canonical G-proteins are involved in bacterial speck and powdery mildew pathogenesis. In addition, we identified non-canonical Gβ proteins that localize to the plasma membrane and whose signaling pathways intersect with PRR signaling pathways. These findings may provide a link between non-host immunity and mlo-based immunity as well as novel targets for engineering broad spectrum resistance in crop plants against multiple biotrophic pathogens.

Abstract Number: P18-687
Session Type: Poster