Ágnes Szatmári1,2, Ágnes M Móricz3, Ildikó Schwarczinger3, Judit Kolozsváriné Nagy3, Ágnes Alberti4, Miklós Pogány3, Zoltán Bozsó5. 1. Plant Protection Institute, ELKH Centre for Agricultural Research, Herman Ottó St. 15, Budapest, 1022, Hungary. szatmari.agnes@ttk.hu. 2. Present address: Chemical Biology Research Group, Institute of Organic Chemistry, ELKH Research Centre for Natural Sciences, Magyar tudósok körútja 2, Budapest, 1117, Hungary. szatmari.agnes@ttk.hu. 3. Plant Protection Institute, ELKH Centre for Agricultural Research, Herman Ottó St. 15, Budapest, 1022, Hungary. 4. Department of Pharmacognosy, Faculty of Pharmacy, Semmelweis University, Üllői St. 26, Budapest, 1085, Hungary. 5. Plant Protection Institute, ELKH Centre for Agricultural Research, Herman Ottó St. 15, Budapest, 1022, Hungary. bozso.zoltan@atk.hu.
Abstract
BACKGROUND: Acetosyringone (3,5-dimethoxy-4-hydroxyacetophenone, AS) is a syringyl-type phenolic compound rarely found in plants in free form. It has been shown earlier to inhibit the growth of Pseudomonas bacteria in the presence of hydrogen peroxide and peroxidase (AS mix). RESULTS: We detected elevated levels of free AS in Nicotiana tabacum and N. benthamiana plants after inducing pattern-triggered immunity (PTI) by injecting bacterial elicitor flg22, or pathogenicity-mutant Pseudomonas syringae pv. syringae 61 hrcC- bacteria; but not after inoculations with compatible or incompatible pathogens at the time of PTI onset. In this study, we demonstrate that the antibacterial effect of the AS mix is general, as growth of several Gram-negative and -positive phytopathogenic bacteria was characteristically inhibited. The inhibition of bacterial metabolism by the AS mix was rapid, shown by the immediate drop of luminescence intensity of P. syringae pv. tomato DC3000 lx strain after addition of AS mix. The mechanism of the bacteriostatic effect was investigated using fluorescent reporter dye assays. SYTOX Green experiments supported others' previous findings that the AS mix does not result in membrane permeabilization. Moreover, we observed that the mode of action could be depolarization of the bacterial cell membrane, as shown by assays carried out with the voltage sensitive dye DIBAC4(3). CONCLUSIONS: Level of free acetosyringone is elevated during plant PTI responses in tobacco leaves (N. tabacum and N. benthamiana). When combined with hydrogen peroxide and peroxidase (AS mix), components of the mix act synergistically to inhibit bacterial metabolism and proliferation rapidly in a wide range of plant pathogens. This effect is related to depolarization rather than to permeabilization of the bacterial cell membrane. Similar AS mixture to the in vivo model might form locally at sites of invading bacterial attachment to the plant cells and the presence of acetosyringone might have an important role in the inhibition of bacterial proliferation during PTI.
BACKGROUND:Acetosyringone (3,5-dimethoxy-4-hydroxyacetophenone, AS) is a syringyl-type phenolic compound rarely found in plants in free form. It has been shown earlier to inhibit the growth of Pseudomonas bacteria in the presence of hydrogen peroxide and peroxidase (AS mix). RESULTS: We detected elevated levels of free AS in Nicotiana tabacum and N. benthamiana plants after inducing pattern-triggered immunity (PTI) by injecting bacterial elicitor flg22, or pathogenicity-mutant Pseudomonas syringae pv. syringae 61 hrcC- bacteria; but not after inoculations with compatible or incompatible pathogens at the time of PTI onset. In this study, we demonstrate that the antibacterial effect of the AS mix is general, as growth of several Gram-negative and -positive phytopathogenic bacteria was characteristically inhibited. The inhibition of bacterial metabolism by the AS mix was rapid, shown by the immediate drop of luminescence intensity of P. syringae pv. tomato DC3000 lx strain after addition of AS mix. The mechanism of the bacteriostatic effect was investigated using fluorescent reporter dye assays. SYTOX Green experiments supported others' previous findings that the AS mix does not result in membrane permeabilization. Moreover, we observed that the mode of action could be depolarization of the bacterial cell membrane, as shown by assays carried out with the voltage sensitive dye DIBAC4(3). CONCLUSIONS: Level of free acetosyringone is elevated during plant PTI responses in tobacco leaves (N. tabacum and N. benthamiana). When combined with hydrogen peroxide and peroxidase (AS mix), components of the mix act synergistically to inhibit bacterial metabolism and proliferation rapidly in a wide range of plant pathogens. This effect is related to depolarization rather than to permeabilization of the bacterial cell membrane. Similar AS mixture to the in vivo model might form locally at sites of invading bacterial attachment to the plant cells and the presence of acetosyringone might have an important role in the inhibition of bacterial proliferation during PTI.
Authors: Laurence V Bindschedler; Julia Dewdney; Kris A Blee; Julie M Stone; Tsuneaki Asai; Julia Plotnikov; Carine Denoux; Tezni Hayes; Chris Gerrish; Dewi R Davies; Frederick M Ausubel; G Paul Bolwell Journal: Plant J Date: 2006-08-02 Impact factor: 6.417
Authors: Hanh P Nguyen; Suma Chakravarthy; André C Velásquez; Heather L McLane; Lirong Zeng; Hitoshi Nakayashiki; Duck-Hwan Park; Alan Collmer; Gregory B Martin Journal: Mol Plant Microbe Interact Date: 2010-08 Impact factor: 4.171