title: Ectopically expressed sweet pepper ferredoxin PFLP enhances disease resistance to Pectobacterium carotovorum subsp. carotovorum affected by harpin and protease-mediated hypersensitive response in Arabidopsis.
abstract: Plant ferredoxin-like protein (PFLP) is a photosynthesis-type ferredoxin (Fd) found in sweet pepper. It contains an iron-sulphur cluster that receives and delivers electrons between enzymes involved in many fundamental metabolic processes. It has been demonstrated that transgenic plants overexpressing PFLP show a high resistance to many bacterial pathogens, although the mechanism remains unclear. In this investigation, the PFLP gene was transferred into Arabidopsis and its defective derivatives, such as npr1 (nonexpresser of pathogenesis-related gene 1) and eds1 (enhanced disease susceptibility 1) mutants and NAHG-transgenic plants. These transgenic plants were then infected with the soft-rot bacterial pathogen Pectobacterium carotovorum subsp. carotovorum (Erwinia carotovora ssp. carotovora, ECC) to investigate the mechanism behind PFLP-mediated resistance. The results revealed that, instead of showing soft-rot symptoms, ECC activated hypersensitive response (HR)-associated events, such as the accumulation of hydrogen peroxide (H2 O2 ), electrical conductivity leakage and expression of the HR marker genes (ATHSR2 and ATHSR3) in PFLP-transgenic Arabidopsis. This PFLP-mediated resistance could be abolished by inhibitors, such as diphenylene iodonium (DPI), 1-l-trans-epoxysuccinyl-leucylamido-(4-guanidino)-butane (E64) and benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone (z-VAD-fmk), but not by myriocin and fumonisin. The PFLP-transgenic plants were resistant to ECC, but not to its harpin mutant strain ECCAC5082. In the npr1 mutant and NAHG-transgenic Arabidopsis, but not in the eds1 mutant, overexpression of the PFLP gene increased resistance to ECC. Based on these results, we suggest that transgenic Arabidopsis contains high levels of ectopic PFLP; this may lead to the recognition of the harpin and to the activation of the HR and other resistance mechanisms, and is dependent on the protease-mediated pathway.
authors.affiliation: Department of Life Science, National University of Kaohsiung, Kaohsiung, 811, Taiwan.
authors.forename: Mang-Jye
authors.initials: MJ
authors.lastname: Ger
authors.forename: Guan-Yu
authors.initials: GY
authors.lastname: Louh
authors.forename: Yi-Hsien
authors.initials: YH
authors.lastname: Lin
authors.forename: Teng-Yung
authors.initials: TY
authors.lastname: Feng
authors.forename: Hsiang-En
authors.initials: HE
authors.lastname: Huang
mesh_terms: D000085:Acetates / Q000378:metabolism; D017360:Arabidopsis / Q000235:genetics / Q000276:immunology* / Q000382:microbiology*; D001426:Bacterial Proteins / Q000378:metabolism*; D002212:Capsicum / Q000378:metabolism*; D003517:Cyclopentanes / Q000378:metabolism; D060467:Disease Resistance; D005288:Ferredoxins / Q000378:metabolism*; D009154:Mutation; D054883:Oxylipins / Q000378:metabolism; D016973:Pectobacterium carotovorum / Q000502:physiology*; D010447:Peptide Hydrolases / Q000378:metabolism*; D030821:Plants, Genetically Modified; D020156:Salicylic Acid / Q000378:metabolism
chemical_list: D000085:Acetates; D001426:Bacterial Proteins; D003517:Cyclopentanes; D005288:Ferredoxins; D054883:Oxylipins; C474922:plant ferredoxin-like protein, Capsicum annuum; C072239:methyl jasmonate; D010447:Peptide Hydrolases; D020156:Salicylic Acid
keywords: Erwinia; NPR1; PFLP; disease resistance; ferredoxin; harpin