NbLRK1, a lectin-like receptor kinase protein of Nicotiana benthamiana, interacts with Phytophthora infestans INF1 elicitin and mediates INF1-induced cell death.

Phytophthora infestans INF1 elicitin causes the hypersensitive response (HR) in Nicotiana benthamiana (Kamoun et al. in Plant Cell 10:1413-1425, 1998). To identify N. benthamiana proteins that interact with INF1, we carried out a yeast two-hybrid screen. This screen resulted in the isolation of a gene NbLRK1 coding for a novel lectin-like receptor kinase. NbLRK1 interacted with INF1 through its VIb kinase subdomain. Purified INF1 and NbLRK1 proteins also interacted in vitro. INF1 treatment of N. benthamiana leaves induced autophosphorylation of NbLRK1. Most importantly, virus-induced gene silencing (VIGS) of NbLRK1 delayed INF1-mediated HR in N. benthamiana. These data suggest that NbLRK1 is a component of the N. benthamiana protein complex that recognizes INF1 elicitor and transduces the HR signal.