A novel fluorimetric method for determination of laccase activity in organic solvents is proposed, based on the oxidation ofo-phenylenediamine (1,2-diaminobenzene, OPDA) catalyzed by laccase yielding 2,3-diaminophenaz...A novel fluorimetric method for determination of laccase activity in organic solvents is proposed, based on the oxidation ofo-phenylenediamine (1,2-diaminobenzene, OPDA) catalyzed by laccase yielding 2,3-diaminophenazine. The optimal conditions for laccase in organic media areT=55°C, pH=6.5, 1.0×10?2mol/L OPDA, 1.25 mL ethanol, 1.25 mL 1,4-dioxane and 1.25 mL acetone. The linear range of the method proposed in ethanol, 1,4-dioxane and acetone media were 0.44–19.33, 0.11–20.85, 0.38–21.05 U with the detection limit of 0.088, 0.022, 0.076 U, respectively. The proposed method has been applied to the analysis of laccase activity of real samples with more accurate and sensitive than that of the previous method reported.展开更多
The brown planthopper （BPH, Nilaparvata lugens） is a destructive, monophagous, piercing-sucking insect pest of rice. Previous studies indicated that jasmonic acid （JA） positively regulates rice defense against che...The brown planthopper （BPH, Nilaparvata lugens） is a destructive, monophagous, piercing-sucking insect pest of rice. Previous studies indicated that jasmonic acid （JA） positively regulates rice defense against chewing insect pests but negatively regulates it against the piercing-sucking insect of BPH. We here demonstrated that overexpression of allene oxide cyclase （AOC） but not OPR3 （cis-12-oxo-phytodienoic acid （OPDA） reductase 3, an enzyme adjacent to AOC in the JA synthetic pathway） significantly increased rice resistance to BPH, mainly by reducing the feeding activity and survival rate. Further anal- ysis revealed that plant response to BPH under AOC overexpression was independent of the JA pathway and that significantly higher OPDA levels stimulated rice resistance to BPH. Microarray analysis identified multiple candidate resistance-related genes underAOCoverexpression. OPDA treatment stimulated the resistance of radish seedlings to green peach aphid Myzus persicae, another piercing-sucking insect. These results imply that rice resistance to chewing insects and to sucking insects can be enhanced simultaneously through AOC-mediated increases of JA and OPDA and provide direct evidence of the potential application of OPDA in stimulating plant defense responses to piercing-sucking insect pests in agriculture.展开更多
Multicellular organisms rely on the movement of signaling molecules across cells,tissues,and organs to communicate among distal sites.In plants,localized leaf damage activates jasmonic acid(JA)-dependent transcription...Multicellular organisms rely on the movement of signaling molecules across cells,tissues,and organs to communicate among distal sites.In plants,localized leaf damage activates jasmonic acid(JA)-dependent transcriptional reprogramming in both harmed and unharmed tissues.Although it has been indicated that JA species can translocate from damaged into distal sites,the identity of the mobile compound(s),the tissues through which they translocate,and the effect of their relocation remain unknown.Here,we found that following shoot wounding,the relocation of endogenous jasmonates through the phloem is essential to initiate JA signaling and stunt growth in unharmed roots of Arabidopsis thaliana.By employing grafting experiments and hormone profiling,we uncovered that the hormone precursor cis-12-oxo-phytodienoic acid(OPDA)and its derivatives,but not the bioactive JA-Ile conjugate,translocate from wounded shoots into undamaged roots.Upon root relocation,the mobile precursors cooperatively regulated JA responses through their conversion into JA-Ile and JA signaling activation.Collectively,our findings demonstrate the existence of long-distance translocation of endogenous OPDA and its derivatives,which serve as mobile molecules to coordinate shoot-to-root responses,and highlight the importance of a controlled redistribution of hormone precursors among organs during plant stress acclimation.展开更多
文摘A novel fluorimetric method for determination of laccase activity in organic solvents is proposed, based on the oxidation ofo-phenylenediamine (1,2-diaminobenzene, OPDA) catalyzed by laccase yielding 2,3-diaminophenazine. The optimal conditions for laccase in organic media areT=55°C, pH=6.5, 1.0×10?2mol/L OPDA, 1.25 mL ethanol, 1.25 mL 1,4-dioxane and 1.25 mL acetone. The linear range of the method proposed in ethanol, 1,4-dioxane and acetone media were 0.44–19.33, 0.11–20.85, 0.38–21.05 U with the detection limit of 0.088, 0.022, 0.076 U, respectively. The proposed method has been applied to the analysis of laccase activity of real samples with more accurate and sensitive than that of the previous method reported.
基金This study was supported by the National Basic Research Program of China （2010CB126200） and the National Natural Science Foundation of China （31371949）.
文摘The brown planthopper （BPH, Nilaparvata lugens） is a destructive, monophagous, piercing-sucking insect pest of rice. Previous studies indicated that jasmonic acid （JA） positively regulates rice defense against chewing insect pests but negatively regulates it against the piercing-sucking insect of BPH. We here demonstrated that overexpression of allene oxide cyclase （AOC） but not OPR3 （cis-12-oxo-phytodienoic acid （OPDA） reductase 3, an enzyme adjacent to AOC in the JA synthetic pathway） significantly increased rice resistance to BPH, mainly by reducing the feeding activity and survival rate. Further anal- ysis revealed that plant response to BPH under AOC overexpression was independent of the JA pathway and that significantly higher OPDA levels stimulated rice resistance to BPH. Microarray analysis identified multiple candidate resistance-related genes underAOCoverexpression. OPDA treatment stimulated the resistance of radish seedlings to green peach aphid Myzus persicae, another piercing-sucking insect. These results imply that rice resistance to chewing insects and to sucking insects can be enhanced simultaneously through AOC-mediated increases of JA and OPDA and provide direct evidence of the potential application of OPDA in stimulating plant defense responses to piercing-sucking insect pests in agriculture.
文摘Multicellular organisms rely on the movement of signaling molecules across cells,tissues,and organs to communicate among distal sites.In plants,localized leaf damage activates jasmonic acid(JA)-dependent transcriptional reprogramming in both harmed and unharmed tissues.Although it has been indicated that JA species can translocate from damaged into distal sites,the identity of the mobile compound(s),the tissues through which they translocate,and the effect of their relocation remain unknown.Here,we found that following shoot wounding,the relocation of endogenous jasmonates through the phloem is essential to initiate JA signaling and stunt growth in unharmed roots of Arabidopsis thaliana.By employing grafting experiments and hormone profiling,we uncovered that the hormone precursor cis-12-oxo-phytodienoic acid(OPDA)and its derivatives,but not the bioactive JA-Ile conjugate,translocate from wounded shoots into undamaged roots.Upon root relocation,the mobile precursors cooperatively regulated JA responses through their conversion into JA-Ile and JA signaling activation.Collectively,our findings demonstrate the existence of long-distance translocation of endogenous OPDA and its derivatives,which serve as mobile molecules to coordinate shoot-to-root responses,and highlight the importance of a controlled redistribution of hormone precursors among organs during plant stress acclimation.
