An extracellular aspartic protease functions in Arabidopsis disease resistance signaling.
We have used activation tagging with T-DNA carrying cauliflower mosaic virus 35S enhancers to investigate the complex signaling networks underlying disease resistance in Arabidopsis. From a screen of approximately 5000 lines, we identified constitutive disease resistance (CDR1) encoding an apoplastic aspartic protease, the overexpression of which causes dwarfing and resistance to virulent Pseudomonas syringae. These phenotypes reflect salicylic-acid-dependent activation of micro-oxidative bursts and various defense-related genes. Antisense CDR1 plants were compromised for resistance to avirulent P. syringae and more susceptible to virulent strains than wild type. CDR1 accumulates in intercellular fluid in response to pathogen attacks. Induction of CDR1 generates a small mobile signal, and CDR1 action is blocked by the protease inhibitor pepstatin and by mutations in the protease active sites. We propose that CDR1 mediates a peptide signal system involved in the activation of inducible resistance mechanisms.
Xia
Yiji
Y
Salk Institute for Biological Studies, La Jolla, CA, USA. yxia@danforthcenter.org
Suzuki
Hideyuki
H
Borevitz
Justin
J
Blount
Jack
J
Guo
Zejian
Z
Patel
Kanu
K
Dixon
Richard A
RA
Lamb
Chris
C
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000276:immunology* / Q000382:microbiology; D029681:Arabidopsis Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D016282:Aspartic Acid Endopeptidases / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D017796:Caulimovirus / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation; D010084:Oxidation-Reduction; D010935:Plant Diseases / Q000235:genetics*; D044224:Pseudomonas syringae; D015398:Signal Transduction
D029681:Arabidopsis Proteins; D016282:Aspartic Acid Endopeptidases; C502093:CDR1 protein, Arabidopsis