Functional analysis of Avr9/Cf-9 rapidly elicited genes identifies a protein kinase, ACIK1, that is essential for full Cf-9-dependent disease resistance in tomato.
Tomato (Lycopersicon esculentum) Cf genes confer resistance to the fungal pathogen Cladosporium fulvum through recognition of secreted avirulence (Avr) peptides. Plant defense responses, including rapid alterations in gene expression, are immediately activated upon perception of the pathogen. Previously, we identified a collection of Avr9/Cf-9 rapidly (15 to 30 min) elicited (ACRE) genes from tobacco (Nicotiana tabacum). Many of the ACRE genes encode putative signaling components and thus may play pivotal roles in the initial development of the defense response. To assess the requirement of 42 of these genes in the hypersensitive response (HR) induced by Cf-9/Avr9 or by Cf-4/Avr4, we used virus-induced gene silencing (VIGS) in N. benthamiana. Three genes were identified that when silenced compromised the Cf-mediated HR. We further characterized one of these genes, which encodes a Ser/Thr protein kinase called Avr9/Cf-9 induced kinase 1 (ACIK1). ACIK1 mRNA was rapidly upregulated in tobacco and tomato upon elicitation by Avr9 and by wounding. Silencing of ACIK1 in tobacco resulted in a reduced HR that correlated with loss of ACIK1 transcript. Importantly, ACIK1 was found to be required for Cf-9/Avr9- and Cf-4/Avr4-mediated HRs but not for the HR or resistance mediated by other resistance/Avr systems, such as Pto/AvrPto, Rx/Potato virus X, or N/Tobacco mosaic virus. Moreover, VIGS of LeACIK1 in tomato decreased Cf-9-mediated resistance to C. fulvum, showing the importance of ACIK1 in disease resistance.
Rowland
Owen
O
Sainsbury Laboratory, John Ines Centre, Norwich NR4 7UH, United Kingdom.
Ludwig
Andrea A
AA
Merrick
Catherine J
CJ
Baillieul
Fabienne
F
Tracy
Frances E
FE
Durrant
Wendy E
WE
Fritz-Laylin
Lillian
L
Nekrasov
Vladimir
V
Sjölander
Kimmen
K
Yoshioka
Hirofumi
H
Jones
Jonathan D G
JD
D004266:DNA Virus Infections / Q000235:genetics; D005656:Fungal Proteins / Q000235:genetics* / Q000494:pharmacology; D018506:Gene Expression Regulation, Plant / Q000187:drug effects / Q000235:genetics*; D020868:Gene Silencing / Q000187:drug effects; D017343:Genes, Plant / Q000235:genetics*; D007113:Immunity, Innate / Q000235:genetics*; D018551:Solanum lycopersicum / Q000201:enzymology / Q000235:genetics / Q000382:microbiology; D008969:Molecular Sequence Data; D010935:Plant Diseases / Q000235:genetics* / Q000382:microbiology; D010940:Plant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D010942:Plant Viruses / Q000235:genetics; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism / Q000494:pharmacology; D013997:Time Factors; D014026:Nicotiana / Q000201:enzymology / Q000235:genetics / Q000382:microbiology; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology
C085987:AVR4 protein, Cladosporium fulvum; D005656:Fungal Proteins; D010940:Plant Proteins; D012333:RNA, Messenger; C073605:AVR9 protein, Cladosporium fulvum; D017346:Protein Serine-Threonine Kinases