Brassinosteroids modulate the efficiency of plant immune responses to microbe-associated molecular patterns

Proc Natl Acad Sci U S A. 2012 Jan 3;109(1):297-302. doi: 10.1073/pnas.1112840108. Epub 2011 Nov 15.


Metazoans and plants use pattern recognition receptors (PRRs) to sense conserved microbial-associated molecular patterns (MAMPs) in the extracellular environment. In plants, the bacterial MAMPs flagellin and elongation factor Tu (EF-Tu) activate distinct, phylogenetically related cell surface pattern recognition receptors of the leucine-rich repeat receptor kinase (LRR-RK) family called FLS2 and EF-Tu receptor, respectively. BAK1 is an LRR-RK coreceptor for both FLS2 and EF-Tu receptor. BAK1 is also a coreceptor for the plant brassinosteroid (BR) receptor, the LRR-RK BRI1. Binding of BR to BRI1 primarily promotes cell elongation. Here, we tune the BR pathway response to establish how plant cells can generate functionally different cellular outputs in response to MAMPs and pathogens. We demonstrate that BR can act antagonistically or synergistically with responses to MAMPs. We further show that the synergistic activities of BRs on MAMP responses require BAK1. Our results highlight the importance of plant steroid homeostasis as a critical step in the establishment of plant immunity. We propose that tradeoffs associated with plasticity in the face of infection are layered atop plant steroid developmental programs.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Arabidopsis / cytology
  • Arabidopsis / drug effects
  • Arabidopsis / immunology*
  • Arabidopsis / microbiology*
  • Arabidopsis Proteins / metabolism
  • Brassinosteroids / biosynthesis
  • Brassinosteroids / metabolism*
  • Brassinosteroids / pharmacology
  • Cell Death / drug effects
  • Flagellin / pharmacology
  • Homeostasis / drug effects
  • Plant Immunity / drug effects
  • Plant Immunity / immunology*
  • Protein Kinases / metabolism
  • Protein-Serine-Threonine Kinases / metabolism
  • Pseudomonas syringae / drug effects
  • Pseudomonas syringae / metabolism*
  • Receptors, Pattern Recognition / metabolism*
  • Signal Transduction / drug effects


  • Arabidopsis Proteins
  • Brassinosteroids
  • Receptors, Pattern Recognition
  • Flagellin
  • Protein Kinases
  • BAK1 protein, Arabidopsis
  • BRI1 protein, Arabidopsis
  • Protein-Serine-Threonine Kinases