Polyamines （PA）, polyamine oxidases, copper amine oxidases, and nitric oxide （NO） play important roles in physiology and stress responses in plants. NO biosynthesis as a result of catabolism of PA by polyamine oxi...Polyamines （PA）, polyamine oxidases, copper amine oxidases, and nitric oxide （NO） play important roles in physiology and stress responses in plants. NO biosynthesis as a result of catabolism of PA by polyamine oxidases and copper amine oxidases may explain in part PA-mediated responses. Involvement of a copper amine oxidase gene, COPPER AMINE OXIDASEI （CuAO1）, of Arabidopsis was tested for its role in stress responses using the knockouts cuao1-1 and cuaol-2. PA-induced and ABA-induced NO production investigated bY fluorometry and fluorescence microscopy showed that the cuaol-1 and cuaol-2 are impaired in NO production, suggesting a function of CuAO1 in PA and ABA-mediated NO production. Furthermore, we found a PA-dependent increase in protein S-nitrosylation. The addition of PA and ABA also resulted in H2O2 increases, cuao1-1 and cuao1-2 showed less sensitivity to exogenous ABA supplementation during germination, seedling establishment, and root growth inhibition as compared to wild-type. In response to ABA treatment, expression levels of the stress-responsive genes RD29A and ADH1 were significantly lower in the knockouts. These observations characterize cuao1-1 and cuao1-2 as ABA-insensitive mutants. Taken together, our findings extend the ABA signal transduction network to include CuAO1 as one potential contributor to enhanced NO production by ABA.展开更多
Echinochloa crus-galli is a major weed in rice fields in China,and quinclorac has been long used for its control.Over-reliance of quinclorac has resulted in quinclorac resistance in E.crus-galli.Two resistant(R)E.crus...Echinochloa crus-galli is a major weed in rice fields in China,and quinclorac has been long used for its control.Over-reliance of quinclorac has resulted in quinclorac resistance in E.crus-galli.Two resistant(R)E.crus-galli populations from Hunan,China were confirmed to be at least 78-fold more resistant to quinclorac than the susceptible(S)population.No difference in foliar uptake of 14C-labelled quinclorac was detected between the R and S plants.However,a higher level of 14C translocation and a lower level of quinclorac metabolism were found in the R plants.Basal and induced expression levels ofβ-cyanoalanine synthase(β-CAS)gene andβ-CAS activity were not significantly different between the R and S plants.However,the induction expression of 1-aminocyclopropane-1-carboxylic acid oxidase(ACO1)gene by quinclorac treatment was evident in the S plants but not in the R plants.Quinclorac resistance in the two resistant E.crus-galli populations was not likely to be related to foliar uptake,translocation or metabolism of quinclorac,nor to cyanide detoxification viaβ-CAS.Thus,target-site based quinclorac signal reception and transduction and regulation of the ethylene synthesis pathway should be the focus for further research.展开更多
基金supported by the National 973 Basic Research Program(No.2012CB933804)the National Natural Science Foundation of China(No.21035002,No.21121091)the Natural Science Foundation of Jiangsu province(No.BK2010009)
文摘Polyamines （PA）, polyamine oxidases, copper amine oxidases, and nitric oxide （NO） play important roles in physiology and stress responses in plants. NO biosynthesis as a result of catabolism of PA by polyamine oxidases and copper amine oxidases may explain in part PA-mediated responses. Involvement of a copper amine oxidase gene, COPPER AMINE OXIDASEI （CuAO1）, of Arabidopsis was tested for its role in stress responses using the knockouts cuao1-1 and cuaol-2. PA-induced and ABA-induced NO production investigated bY fluorometry and fluorescence microscopy showed that the cuaol-1 and cuaol-2 are impaired in NO production, suggesting a function of CuAO1 in PA and ABA-mediated NO production. Furthermore, we found a PA-dependent increase in protein S-nitrosylation. The addition of PA and ABA also resulted in H2O2 increases, cuao1-1 and cuao1-2 showed less sensitivity to exogenous ABA supplementation during germination, seedling establishment, and root growth inhibition as compared to wild-type. In response to ABA treatment, expression levels of the stress-responsive genes RD29A and ADH1 were significantly lower in the knockouts. These observations characterize cuao1-1 and cuao1-2 as ABA-insensitive mutants. Taken together, our findings extend the ABA signal transduction network to include CuAO1 as one potential contributor to enhanced NO production by ABA.
基金financially supported by the National Natural Science Foundation of China (Grant Nos. 31701803 and 31772182)the Natural Science Foundation of Hunan Province (Grant No. 2017JJ3164) in China and the Australian Grains Research and Development Corporation (GRDC)
文摘Echinochloa crus-galli is a major weed in rice fields in China,and quinclorac has been long used for its control.Over-reliance of quinclorac has resulted in quinclorac resistance in E.crus-galli.Two resistant(R)E.crus-galli populations from Hunan,China were confirmed to be at least 78-fold more resistant to quinclorac than the susceptible(S)population.No difference in foliar uptake of 14C-labelled quinclorac was detected between the R and S plants.However,a higher level of 14C translocation and a lower level of quinclorac metabolism were found in the R plants.Basal and induced expression levels ofβ-cyanoalanine synthase(β-CAS)gene andβ-CAS activity were not significantly different between the R and S plants.However,the induction expression of 1-aminocyclopropane-1-carboxylic acid oxidase(ACO1)gene by quinclorac treatment was evident in the S plants but not in the R plants.Quinclorac resistance in the two resistant E.crus-galli populations was not likely to be related to foliar uptake,translocation or metabolism of quinclorac,nor to cyanide detoxification viaβ-CAS.Thus,target-site based quinclorac signal reception and transduction and regulation of the ethylene synthesis pathway should be the focus for further research.
