The BRI1-Associated Kinase 1, BAK1, Has a Brassinolide-Independent Role in Plant Cell-Death Control

Birgit Kemmerling, Anne Schwedt, Patricia Rodriguez, Sara Mazzotta, Markus Frank, Synan Abu Qamar, Tesfaye Mengiste, Shigeyuki Betsuyaku, Jane E. Parker, Carsten Müssig, Bart P.H.J. Thomma, Catherine Albrecht, Sacco C. de Vries, Heribert Hirt, Thorsten Nürnberger*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

310 Scopus citations


Programmed cell death (PCD) is a common host response to microbial infection [1-3]. In plants, PCD is associated with immunity to biotrophic pathogens, but it can also promote disease upon infection by necrotrophic pathogens [4]. Therefore, plant cell-suicide programs must be strictly controlled. Here we demonstrate that the Arabidopsis thaliana Brassinosteroid Insensitive 1 (BRI1)-associated receptor Kinase 1 (BAK1), which operates as a coreceptor of BRI1 in brassinolide (BL)-dependent plant development, also regulates the containment of microbial infection-induced cell death. BAK1-deficient plants develop spreading necrosis upon infection. This is accompanied by production of reactive oxygen intermediates and results in enhanced susceptibility to necrotrophic fungal pathogens. The exogenous application of BL rescues growth defects of bak1 mutants but fails to restore immunity to fungal infection. Moreover, BL-insensitive and -deficient mutants do not exhibit spreading necrosis or enhanced susceptibility to fungal infections. Together, these findings suggest that plant steroid-hormone signaling is dispensable for the containment of infection-induced PCD. We propose a novel, BL-independent function of BAK1 in plant cell-death control that is distinct from its BL-dependent role in plant development.

Original languageEnglish (US)
Pages (from-to)1116-1122
Number of pages7
JournalCurrent Biology
Issue number13
StatePublished - Jul 3 2007
Externally publishedYes

Bibliographical note

Funding Information:
We thank K. Schumacher, J. Chory, T. Nakagawa, A. Gust, and F. Tax for materials; V. Lipka and F. Tax for comments; and M. Tör for sharing data. We acknowledge the Salk Institute, Nottingham Arabidopsis Stock Center (NASC), and American Biological Resource Center (ABRC) collections for mutant seeds and the AtGenExpress Initiative for sharing data sets. This work was supported by the Deutsche Forschungsgemeinschaft (Arabidopsis Functional Genomics Network [AFGN], SFB446) (T.N.), Deutscher Akademischer Austauschdienst (P.R.), the Max-Planck-Society DFG SFB 635 (J.E.P.), and The Japan Society for the Promotion of Young Scientists (S.B.).



ASJC Scopus subject areas

  • General Biochemistry, Genetics and Molecular Biology
  • General Agricultural and Biological Sciences


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