title: The F-box protein ACRE189/ACIF1 regulates cell death and defense responses activated during pathogen recognition in tobacco and tomato.
abstract: Virus-induced gene silencing identified the Avr9/Cf-9 RAPIDLY ELICITED gene ACRE189 as essential for the Cf-9- and Cf-4-mediated hypersensitive response (HR) in Nicotiana benthamiana. We report a role for ACRE189 in disease resistance in tomato (Solanum lycopersicum) and tobacco (Nicotiana tabacum). ACRE189 (herein renamed Avr9/Cf-9-INDUCED F-BOX1 [ACIF1]) encodes an F-box protein with a Leu-rich-repeat domain. ACIF1 is widely conserved and is closely related to F-box proteins regulating plant hormone signaling. Silencing of tobacco ACIF1 suppressed the HR triggered by various elicitors (Avr9, Avr4, AvrPto, Inf1, and the P50 helicase of Tobacco mosaic virus [TMV]). ACIF1 is recruited to SCF complexes (a class of ubiquitin E3 ligases), and the expression of ACIF1 F-box mutants in tobacco compromises the HR similarly to ACIF1 silencing. ACIF1 affects N gene-mediated responses to TMV infection, including lesion formation and salicylic acid accumulation. Loss of ACIF1 function also reduced confluent cell death induced by Pseudomonas syringae pv tabaci. ACIF1 silencing in Cf9 tomato attenuated the Cf-9-dependent HR but not Cf-9 resistance to Cladosporium fulvum. Resistance conferred by the Cf-9 homolog Cf-9B, however, was compromised in ACIF1-silenced tomato. Analysis of public expression profiling data suggests that Arabidopsis thaliana homologs of ACIF1 (VFBs) regulate defense responses via methyl jasmonate- and abscisic acid-responsive genes. Together, these findings support a role of ACIF1/VFBs in plant defense responses.
authors: Sainsbury Laboratory, John Ines Centre, Norwich NR4 7UH, United Kingdom.
authors: Harrold A
authors: HA
authors: van den Burg
authors: Dimitrios I
authors: DI
authors: Tsitsigiannis
authors: Owen
authors: O
authors: Rowland
authors: Jane
authors: J
authors: Lo
authors: Ghanasyam
authors: G
authors: Rallapalli
authors: Daniel
authors: D
authors: Maclean
authors: Frank L W
authors: FL
authors: Takken
authors: Jonathan D G
authors: JD
authors: Jones
mesh_terms: D000595:Amino Acid Sequence; D016923:Cell Death / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D018506:Gene Expression Regulation, Plant; D020868:Gene Silencing; D015151:Immunoblotting; D018551:Solanum lycopersicum / Q000235:genetics* / Q000378:metabolism / Q000382:microbiology; D008969:Molecular Sequence Data; D020411:Oligonucleotide Array Sequence Analysis; D010802:Phylogeny; D010935:Plant Diseases / Q000235:genetics* / Q000382:microbiology; D010940:Plant Proteins / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified; D011485:Protein Binding; D044224:Pseudomonas syringae / Q000254:growth & development; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D014026:Nicotiana / Q000235:genetics* / Q000378:metabolism / Q000382:microbiology; D014027:Tobacco Mosaic Virus / Q000254:growth & development
chemical_list: D010940:Plant Proteins