The chimeric Arabidopsis CYCLIC NUCLEOTIDE-GATED ION CHANNEL11/12 activates multiple pathogen resistance responses.
To investigate the resistance signaling pathways activated by pathogen infection, we previously identified the Arabidopsis thaliana mutant constitutive expresser of PR genes22 (cpr22), which displays constitutive activation of multiple defense responses. Here, we identify the cpr22 mutation as a 3-kb deletion that fuses two cyclic nucleotide-gated ion channel (ATCNGC)-encoding genes, ATCNGC11 and ATCNGC12, to generate a novel chimeric gene, ATCNGC11/12. Genetic, molecular, and complementation analyses suggest that ATCNGC11/12, as well as ATCNGC11 and ATCNGC12, form functional cAMP-activated ATCNGCs and that the phenotype conferred by cpr22 is attributable to the expression of ATCNGC11/12. However, because overexpression of ATCNGC12, but not ATCNGC11, suppressed the phenotype conferred by cpr22, the development of this phenotype appears to be regulated by the ratio between ATCNGC11/12 and ATCNGC12. Analysis of knockout lines revealed that both ATCNGC11 and ATCNGC12 are positive mediators of resistance against an avirulent biotype of Hyaloperonospora parasitica. Through epistatic analyses, cpr22-mediated enhanced resistance to pathogens was found to require NDR1-dependent and EDS1/PAD4-dependent pathways. In striking contrast, none of these pathways was required for cpr22-induced salicylic acid accumulation or PR-1 gene expression. These results demonstrate that NDR1, EDS1, and PAD4 mediate other resistance signaling function(s) in addition to salicylic acid and pathogenesis-related protein accumulation. Moreover, the requirement for both NDR1-dependent and EDS1/PAD4-dependent pathways for cpr22-mediated resistance suggests that these pathways are cross-regulated.
Yoshioka
Keiko
K
Boyce Thompson Institute for Plant Research, Ithaca, New York 14853, USA. yoshioka@botany.utoronto.ca
Moeder
Wolfgang
W
Kang
Hong-Gu
HG
Kachroo
Pradeep
P
Masmoudi
Khaled
K
Berkowitz
Gerald
G
Klessig
Daniel F
DF
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000033:anatomy & histology / Q000235:genetics* / Q000382:microbiology*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D001483:Base Sequence; D032461:Chromosomes, Plant / Q000235:genetics; D003001:Cloning, Molecular; D054815:Cyclic Nucleotide-Gated Cation Channels; D007113:Immunity, Innate / Q000502:physiology; D007473:Ion Channels / Q000235:genetics* / Q000502:physiology; D008969:Molecular Sequence Data; D050506:Mutant Chimeric Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D009154:Mutation; D010641:Phenotype; D020161:Physical Chromosome Mapping; D010935:Plant Diseases / Q000382:microbiology; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism / Q000382:microbiology; D016415:Sequence Alignment; D017384:Sequence Deletion; D015398:Signal Transduction; D014026:Nicotiana / Q000235:genetics
D029681:Arabidopsis Proteins; C510425:CNGC11 protein, Arabidopsis; C510426:CNGC12 protein, Arabidopsis; D054815:Cyclic Nucleotide-Gated Cation Channels; D007473:Ion Channels; D050506:Mutant Chimeric Proteins; C077262:PR-1 protein, Arabidopsis