Arabidopsis DND2, a second cyclic nucleotide-gated ion channel gene for which mutation causes the "defense, no death" phenotype.
A previous mutant screen identified Arabidopsis dnd1 and dnd2 "defense, no death" mutants, which exhibit loss of hypersensitive response (HR) cell death without loss of gene-for-gene resistance. The dnd1 phenotype is caused by mutation of the gene encoding cyclic nucleotide-gated (CNG) ion channel AtCNGC2. This study characterizes dnd2 plants. Even in the presence of high titers of Pseudomonas syringae expressing avrRpt2, most leaf mesophyll cells in the dnd2 mutant exhibited no HR. These plants retained strong RPS2-, RPM1-, or RPS4-mediated restriction of P. syringae pathogen growth. Mutant dnd2 plants also exhibited enhanced broad-spectrum resistance against virulent P. syringae and constitutively elevated levels of salicylic acid, and pathogenesis-related (PR) gene expression. Unlike the wild type, dnd2 plants responding to virulent and avirulent P. syringae exhibited elevated expression of both salicylate-dependent PR-1 and jasmonate and ethylene-dependent PDF1.2. Introduction of nahG+ (salicylate hydroxylase) into the dnd2 background, which removes salicylic acid and causes other defense alterations, eliminated constitutive disease resistance and PR gene expression but only weakly impacted the HR- phenotype. Map-based cloning revealed that dnd2 phenotypes are caused by mutation of a second CNG ion channel gene, AtCNGC4. Hence, loss of either of two functionally nonredundant CNG ion channels can cause dnd phenotypes. The dnd mutants provide a unique genetic background for dissection of defense signaling.
Jurkowski
Grace I
GI
Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI 53706, USA.
Smith
Roger K
RK
Yu
I-ching
IC
Ham
Jong Hyun
JH
Sharma
Shashi B
SB
Klessig
Daniel F
DF
Fengler
Kevin A
KA
Bent
Andrew F
AF
D017360:Arabidopsis / Q000235:genetics* / Q000382:microbiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D054815:Cyclic Nucleotide-Gated Cation Channels; D003517:Cyclopentanes / Q000494:pharmacology; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D007113:Immunity, Innate / Q000235:genetics; D007473:Ion Channels / Q000235:genetics* / Q000378:metabolism; D009154:Mutation; D054883:Oxylipins; D010641:Phenotype; D010935:Plant Diseases / Q000235:genetics* / Q000382:microbiology; D044224:Pseudomonas syringae / Q000254:growth & development; D020156:Salicylic Acid / Q000378:metabolism
D029681:Arabidopsis Proteins; D054815:Cyclic Nucleotide-Gated Cation Channels; D003517:Cyclopentanes; D007473:Ion Channels; D054883:Oxylipins; C077262:PR-1 protein, Arabidopsis; C011006:jasmonic acid; D020156:Salicylic Acid