Evidence that the BONZAI1/COPINE1 protein is a calcium- and pathogen-responsive defense suppressor.
Copines are calcium-responsive, phospholipid-binding proteins involved in cellular signaling. The Arabidopsis BONZAI1/COPINE1 (BON1/CPN1) gene is a suppressor of defense responses controlled by the disease resistance (R) gene homolog SNC1. The BON1/CPN1 null mutant cpn1-1 has a recessive, temperature- and humidity-dependent, lesion mimic phenotype that includes activation of Pathogenesis-Related (PR) gene expression. Here, we demonstrated that the accumulation of BON1/CPN1 protein in wild-type plants was up-regulated by bacterial pathogen inoculation and by the activation of defense signaling responses controlled by two R genes, SNC1 and RPS2. Interestingly, however, over-accumulation of BON1/CPN1 in two BON1/CPN1 promoter T-DNA insertion mutants did not affect resistance to a bacterial pathogen. Promoter deletion analysis identified a 280 bp segment of the BON1/CPN1 promoter as being required for pathogen-induced gene expression; the same promoter region was also required for calcium ionophore-induced gene expression. Leaf infiltration with calcium ionophore triggered high-level PR gene expression specifically in cpn1-1 plants grown under permissive conditions, while co-infiltration of the calcium chelator EGTA attenuated this effect. These results explain the conditional nature of the cpn1-1 phenotype and are consistent with BON1/CPN1 being a calcium- and pathogen-responsive plant defense suppressor.
Lee
Tzuu-Fen
TF
211 Buckhout Laboratory, Plant Pathology Department, Pennsylvania State University, University Park, PA 16802, USA.
McNellis
Timothy W
TW
D017360:Arabidopsis / Q000235:genetics / Q000382:microbiology / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000502:physiology*; D001483:Base Sequence; D015139:Blotting, Southern; D002118:Calcium / Q000378:metabolism*; D002135:Calcium-Binding Proteins; D002352:Carrier Proteins / Q000235:genetics / Q000502:physiology*; D017931:DNA Primers; D008565:Membrane Proteins / Q000235:genetics / Q000502:physiology*; D016133:Polymerase Chain Reaction; D044224:Pseudomonas syringae / Q000472:pathogenicity
D029681:Arabidopsis Proteins; C436490:BON1 protein, Arabidopsis; D002135:Calcium-Binding Proteins; D002352:Carrier Proteins; D017931:DNA Primers; D008565:Membrane Proteins; D002118:Calcium