CBP60g and SARD1 play partially redundant critical roles in salicylic acid signaling

Plant J. 2011 Sep;67(6):1029-41. doi: 10.1111/j.1365-313X.2011.04655.x. Epub 2011 Jul 6.


Arabidopsis thaliana calmodulin binding protein 60g (CBP60g) contributes to production of salicylic acid (SA) in response to recognition of microbe-associated molecular patterns (MAMPs) such as flg22, a fragment of bacterial flagellin. Calmodulin binding is required for the function of CBP60g in limiting growth of the bacterial pathogen Pseudomonas syringae pv. maculicola (Pma) ES4326 and activation of SA synthesis. Here, we describe a closely related protein, SARD1. Unlike CBP60g, SARD1 does not bind calmodulin. Growth of Pma ES4326 is enhanced in sard1 mutants. In cbp60g sard1 double mutants, growth of Pma ES4326 is greatly enhanced, and SA levels and expression of PR-1 and SID2 are dramatically reduced. Expression profiling placed the CBP60g/SARD1 node between the PAD4/EDS1 and SA nodes in the defense signaling network, and indicated that CBP60g and SARD1 affect defense responses in addition to SA production. A DNA motif bound by CBP60g and SARD1, GAAATTT, was significantly over-represented in promoters of CBP60g/SARD1-dependent genes, suggesting that expression of these genes is modulated by CBP60g/SARD1 binding. Gene expression patterns showed a stronger effect of cbp60g mutations soon after activation of a defense response, and a stronger effect of sard1 mutations at later times. The results are consistent with a model in which CBP60g and SARD1 comprise a partially redundant protein pair that is required for activation of SA production as well as other defense responses, with CBP60g playing a more important role early during the defense response, and SARD1 to playing a more important role later.

Publication types

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

MeSH terms

  • Arabidopsis / genetics
  • Arabidopsis / metabolism
  • Arabidopsis / microbiology
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism*
  • Calmodulin / metabolism
  • Calmodulin-Binding Proteins / genetics
  • Calmodulin-Binding Proteins / metabolism*
  • Carboxylic Ester Hydrolases / genetics
  • Carboxylic Ester Hydrolases / metabolism
  • Disease Resistance
  • Flagellin / metabolism
  • Gene Expression Regulation, Plant
  • Glucans / metabolism
  • Host-Pathogen Interactions
  • Intramolecular Transferases / genetics
  • Intramolecular Transferases / metabolism
  • Mitogen-Activated Protein Kinase Kinases / genetics
  • Mitogen-Activated Protein Kinase Kinases / metabolism
  • Mitogen-Activated Protein Kinases / genetics
  • Mitogen-Activated Protein Kinases / metabolism
  • Mutation
  • Nucleotide Motifs
  • Plant Diseases / microbiology
  • Promoter Regions, Genetic
  • Pseudomonas syringae / pathogenicity
  • Salicylic Acid / metabolism*
  • Signal Transduction


  • Arabidopsis Proteins
  • CBP60g protein, Arabidopsis
  • Calmodulin
  • Calmodulin-Binding Proteins
  • Glucans
  • SARD1 protein, Arabidopsis
  • Flagellin
  • PR-1 protein, Arabidopsis
  • callose
  • AtMPK3 protein, Arabidopsis
  • MPK6 protein, Arabidopsis
  • Mitogen-Activated Protein Kinases
  • Mitogen-Activated Protein Kinase Kinases
  • Carboxylic Ester Hydrolases
  • PAD4 protein, Arabidopsis
  • Intramolecular Transferases
  • isochorismate synthase
  • Salicylic Acid