The proline-rich, extensin-like receptor kinase-1 (PERK1) gene is rapidly induced by wounding

We report the isolation and characterization of PERKI (Proline Extensin-like Receptor Kinase 1), a novel plant RLK from Brassica napus that is predicted to consist of a proline-rich extracellular domain with sequence similarity to extensins, a transmembrane region, and a catalytic domain possessing serine/threonine kinase activity. Database searches with the predicted PERK1 amino acid sequence also led to the identification of a predicted family of related genes in the Arabidopsis genome. Using biolistic bombardment of onion epidermal cells, we have shown that a PERK1-GFP fusion is localized to the plasma membrane as predicted for a receptor kinase. Given the similarity of PERK1's extracellular domain to extensins, a possible role in plant defense responses was investigated by treating B. napus tissue with mechanical stresses and infection with the fungal pathogen, Sclerotinia sclerotiorum. Various wounding stimuli resulted in a dramatic and rapid accumulation of PERK1 mRNA. Levels of PERK1 mRNA also increased moderately in response to infection by the fungal pathogen S. sclerotiorum. Given the kinetics of PERK1 mRNA accumulation in response to these treatments, PERK1 may be involved early on in the general perception and response to a wound and/or pathogen stimulus.