A key aspect of the plant innate immune system is the recognition of invading pathogens. This occurs through plasma membrane localised pattern recognition receptors (PRRs) detecting conserved pathogen signatures, termed pathogen-associated molecular patterns (PAMPs). In Arabidopsis thaliana CERK1 is a lysin motif receptor-like kinase (LYK), which is involved in the perception of chitin released from invading fungal pathogens. In comparison to the five members of the LYK gene family in Arabidopsis, we have identified ten members of the gene family in grapevine (Vitis vinifera), three of which (VvLYK1-1, VvLYK1-2 & VvLYK1-3) are highly homologous to CERK1. VvLYK1-1:GFP was shown to localise to the plasma membrane. Expression of VvLYK1-1 in the Atcerk1 mutant background restored chitin-induced defense responses as demonstrated by MAPK activation and infection assays with the non-adapted grapevine powdery mildew pathogen, Erysiphe necator. This suggests that VvLYK1-1 plays a key role in PAMP-triggered immunity to powdery mildew in grapevine. The kinase domain of VvLYK1-1 was used as a bait in a yeast two-hybrid screen to search for interacting factors. The yeast two-hybrid screen identified a U-box E3 ubiquitin ligase, which shows high homology to the Arabidopsis PUB13 protein. PUB13 has been previously demonstrated to polyubiquitinate FLS2, the receptor of bacterial flagellin (flg22), and promote flagellin-induced FLS2 endocytosis and subsequent degradation.