Coronatine promotes Pseudomonas syringae virulence in plants by activating a signaling cascade that inhibits salicylic acid accumulation.
Phytopathogens can manipulate plant hormone signaling to access nutrients and counteract defense responses. Pseudomonas syringae produces coronatine, a toxin that mimics the plant hormone jasmonic acid isoleucine and promotes opening of stomata for bacterial entry, bacterial growth in the apoplast, systemic susceptibility, and disease symptoms. We examined the mechanisms underlying coronatine-mediated virulence and show that coronatine activates three homologous NAC transcription factor (TF) genes, ANAC019, ANAC055, and ANAC072, through direct activity of the TF, MYC2. Genetic characterization of NAC TF mutants demonstrates that these TFs mediate coronatine-induced stomatal reopening and bacterial propagation in both local and systemic tissues by inhibiting the accumulation of the key plant immune signal salicylic acid (SA). These NAC TFs exert this inhibitory effect by repressing ICS1 and activating BSMT1, genes involved in SA biosynthesis and metabolism, respectively. Thus, a signaling cascade by which coronatine confers its multiple virulence activities has been elucidated.
Department of Biology, Duke University, Durham, NC 27708, USA.
Xiao-Yu
XY
Zheng
Natalie Weaver
NW
Spivey
Weiqing
W
Zeng
Po-Pu
PP
Liu
Zheng Qing
ZQ
Fu
Daniel F
DF
Klessig
Sheng Yang
SY
He
Xinnian
X
Dong
D000596:Amino Acids / Q000633:toxicity*; D017360:Arabidopsis / Q000382:microbiology; D007192:Indenes / Q000633:toxicity*; D010935:Plant Diseases / Q000382:microbiology*; D010940:Plant Proteins / Q000378:metabolism; D044224:Pseudomonas syringae / Q000378:metabolism / Q000472:pathogenicity*; D020156:Salicylic Acid / Q000378:metabolism*; D015398:Signal Transduction; D015533:Transcriptional Activation; D014774:Virulence; D037521:Virulence Factors / Q000633:toxicity*
D000596:Amino Acids; D007192:Indenes; D010940:Plant Proteins; D037521:Virulence Factors; C058487:coronatine; D020156:Salicylic Acid