Activation of a COI1-dependent pathway in Arabidopsis by Pseudomonas syringae type III effectors and coronatine.
Gram-negative bacteria use a variety of virulence factors including phytotoxins, exopolysaccharides, effectors secreted by the type III secretion system, and cell-wall-degrading enzymes to promote parasitism in plants. However, little is known about how these virulence factors alter plant cellular responses to promote disease. In this study, we show that virulent Pseudomonas syringae strains activate the transcription of an Arabidopsis ethylene response factor (ERF) gene, RAP2.6, in a coronatine insensitive 1 (COI1)-dependent manner. A highly sensitive RAP2.6 promoter-firefly luciferase (RAP2.6-LUC) reporter line was developed to monitor activities of various bacterial virulence genes. Analyses of P. syringae pv. tomato DC3000 mutants indicated that both type III secretion system and the phytotoxin coronatine are required for RAP2.6 induction. We show that at least five individual type III effectors, avirulence B (AvrB), AvrRpt2, AvrPphB, HopPtoK, and AvrPphEPto, contributed to RAP2.6 induction. Gene-for-gene recognition was not involved in RAP2.6 induction because plants lacking RPM1 and RPS2 responded normally to AvrB and AvrRpt2 in RAP2.6 expression. Interestingly, the role of coronatine in RAP2.6 induction can be partially substituted by the addition of avrB in DC3000, suggesting that AvrB may mimic coronatine. These results suggest that P. syringae type III effectors and coronatine act by augmenting a COI1-dependent pathway to promote parasitism.
He
Ping
P
Department of Plant Pathology, Kansas State University, Manhattan, KS 66506, USA.
Chintamanani
Satya
S
Chen
Zhongying
Z
Zhu
Lihuang
L
Kunkel
Barbara N
BN
Alfano
James R
JR
Tang
Xiaoyan
X
Zhou
Jian-Min
JM
D000596:Amino Acids / Q000235:genetics / Q000502:physiology*; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000382:microbiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D003517:Cyclopentanes / Q000378:metabolism / Q000494:pharmacology; D005030:Ethylenes / Q000494:pharmacology; D015964:Gene Expression Regulation, Bacterial; D018506:Gene Expression Regulation, Plant; D007113:Immunity, Innate / Q000187:drug effects / Q000235:genetics; D007192:Indenes; D009154:Mutation; D054883:Oxylipins; D010935:Plant Diseases / Q000382:microbiology; D010937:Plant Growth Regulators / Q000494:pharmacology; D011401:Promoter Regions, Genetic / Q000235:genetics; D044224:Pseudomonas syringae / Q000235:genetics* / Q000472:pathogenicity; D020156:Salicylic Acid / Q000494:pharmacology; D014774:Virulence / Q000235:genetics
D000596:Amino Acids; D029681:Arabidopsis Proteins; C100931:AvrB protein, Pseudomonas syringae; D001426:Bacterial Proteins; C112279:COI1 protein, Arabidopsis; D003517:Cyclopentanes; D005030:Ethylenes; D007192:Indenes; D054883:Oxylipins; D010937:Plant Growth Regulators; C089426:RPS2 protein, Arabidopsis; C420919:avrRpt2 protein, Pseudomonas syringae; C058487:coronatine; C011006:jasmonic acid; C036216:ethylene; D020156:Salicylic Acid