Abstract - Rust diseases are a serious threat to cereals and other crops worldwide. The interaction between flax and the flax rust fungus, Melampsora lini, is a model pathosystem helping us to understand the molecular basis of rust fungal pathogenicity in plants. The AvrP effector protein is translocated into the plant cell by the pathogen to facilitate infection. To investigate the role of AvrP, plant interactors were identified via a yeast two hybrid (Y2H) screen and confirmed by in planta assays. AvrP was found to interact with flax phosphoglucomutase and DEAD Box RNA Helicase 56 (DRH56). Further Y2H analysis showed that AvrP targets the phosphate binding domain of phosphoglucomutase. In an in vitro enzymatic assay, purified AvrP protein was able to modulate phosphoglucomutase activity for increased glucose 6-phosphate production. Bimolecular fluorescence complementation analysis showed that AvrP and DRH56 interact inside plant nuclei and co-expression of AvrP and DRH56 in Nicotiana benthamiana leaves resulted in cell death. Mutational disruption of DRH56 ATPase activity did not abolish its interaction with AvrP nor their ability to induce cell death in N. benthamiana. RNA-seq analysis revealed that AvrP has a broad disruptive effect on the flax transcriptome. Overall, these results suggest that AvrP is a bifunctional effector able to affect both glucose and RNA metabolism by manipulation of flax phosphoglucomutase and DRH56, respectively.