1. Department of Genetics, Harvard Medical School, and Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA
2. Instituto de Desarrollo Regional, Sección de Biotecnología, Campus Universitario s/n, E-02071 Albacete, Spain
3. Friedrich Miescher-Institute, PO Box 2543, CH-4002 Basel, Switzerland
4. These authors contributed equally to the work

Correspondence to: Jen Sheen¹ Correspondence and requests for materials should be addressed to J.S. (e-mail: Email: sheen@molbio.mgh.harvard.edu).

Abstract

There is remarkable conservation in the recognition of pathogen-associated molecular patterns (PAMPs) by innate immune responses of plants, insects and mammals. We developed an Arabidopsis thaliana leaf cell system based on the induction of early-defence gene transcription by flagellin, a highly conserved component of bacterial flagella that functions as a PAMP in plants and mammals. Here we identify a complete plant MAP kinase cascade (MEKK1, MKK4/MKK5 and MPK3/MPK6) and WRKY22/WRKY29 transcription factors that function downstream of the flagellin receptor FLS2, a leucine-rich-repeat (LRR) receptor kinase. Activation of this MAPK cascade confers resistance to both bacterial and fungal pathogens, suggesting that signalling events initiated by diverse pathogens converge into a conserved MAPK cascade.