Pathogen-associated molecular patterns(PAMPs)-triggered immunity(PTI)is an important component of plant innate immunity.In a previous study,we showed that the PAMP flg22 from Xanthomonas citri ssp.citri(Xflg22),the ca...Pathogen-associated molecular patterns(PAMPs)-triggered immunity(PTI)is an important component of plant innate immunity.In a previous study,we showed that the PAMP flg22 from Xanthomonas citri ssp.citri(Xflg22),the causal agent of citrus canker,induced PTI in citrus,which correlated with the observed levels of canker resistance.Here,we identified and sequenced two bacterial flagellin/flg22 receptors(FLS2-1 and FLS2-2)from‘Duncan’grapefruit(Citrus paradisi,CpFLS2-1 and CpFLS2-2)and‘Sun Chu Sha’mandarin(C.reticulata,CrFLS2-1 and CrFLS2-2).We were able to isolate only one FLS2 from‘Nagami’kumquat(Fortunella margarita,FmFLS2-1)and gene flanking sequences suggest a rearrangement event that resulted in the deletion of FLS2-2 from the genome.Phylogenetic analysis,gene structure and presence of critical amino acid domains all indicate we identified the true FLS2 genes in citrus.FLS2-2 was more transcriptionally responsive to Xflg22 than FLS2-1,with induced expression levels higher in canker-resistant citrus than in susceptible ones.Interestingly,‘Nagami’kumquat showed the highest FLS2-1 steady-state expression levels,although it was not induced by Xflg22.We selected FmFLS2-1,CrFLS2-2 and CpFLS2-2 to further evaluate their capacity to enhance bacterial resistance using Agrobacterium-mediated transient expression assays.Both FmFLS2-1 and CrFLS2-2,the two proteins from canker-resistant species,conferred stronger Xflg22 responses and reduced canker symptoms in leaves of the susceptible grapefruit genotype.These two citrus genes will be useful resources to enhance PTI and achieve resistance against canker and possibly other bacterial pathogens in susceptible citrus types.展开更多
This study compared the control effect of 110 g/L etoxazole SC,15%abamectin·etoxazole SC,30%cyetpyrafen SC,43%bifenazate SC and 1.8%abamectin EC five acaricides sprayed by unmanned aerial vehicle(UAV)on Panonychu...This study compared the control effect of 110 g/L etoxazole SC,15%abamectin·etoxazole SC,30%cyetpyrafen SC,43%bifenazate SC and 1.8%abamectin EC five acaricides sprayed by unmanned aerial vehicle(UAV)on Panonychus citri,aiming to screen out the appropriate acaricide for the control of this pest by UAV spraying.The results showed that 15%abamectin·etoxazole SC and 30%cyetpyrafen SC had the highest control efficacy,which remained above 90%14 d after application.Secondary performance was observed in 43%bifenazate SC and 110 g/L etoxazole SC,which demonstrated enhancing control effect.However,1.8%abamectin EC showed slower effect.Considering the control effect and population reduction rate of P.citri,15%abamectin·etoxazole SC and 30%cyetpyrafen SC were suggested as the effective acaricides for the control of this pest.展开更多
Xcc （Xanthomonas citri subsp, citri） causes citrus bacterial canker, a leaf, stem and fruit spotting disease that affects most commercial citrus species and cultivars. Copper compounds, widely used for management of...Xcc （Xanthomonas citri subsp, citri） causes citrus bacterial canker, a leaf, stem and fruit spotting disease that affects most commercial citrus species and cultivars. Copper compounds, widely used for management of this pathogen, have been reported as inducers of a VBNC （viable but non-culturable state） in plant pathogenic bacteria. VBNC may be considered as a state preceding bacterial death or as a survival mechanism under adverse conditions. Several experiments were performed to characterize the reversibility and persistence of the VBNC state in Xcc. VBNC was induced in low nutrient medium or with amendment of copper at concentrations used for field disease control. The VBNC condition was demonstrated to persist up to 150 days after copper treatment and was reversed after the addition of culture media without copper or amendment with citrus leaf extract. Xcc viability was evaluated by recovery of colonies on culture media, confirmed by membrane integrity, respiratory activity and by real-time RT-PCR targeting a sequence from the gumD gene. Besides, the colonies recovered were pathogenic on citrus leaves. These results confirm that the VBNC state in Xcc is inducible and reversible and therefore may occur in the phyllosphere when Xcc is under copper stress or starvation.展开更多
In order to systematically investigate the chemical constituents of Citri Reticulatae Folium （leaves of ＇Fuju＇）, an analytical method that included high-performance liquid chromatography, diode array detection, el...In order to systematically investigate the chemical constituents of Citri Reticulatae Folium （leaves of ＇Fuju＇）, an analytical method that included high-performance liquid chromatography, diode array detection, electrospray ionization, and ion-trap time-of-flight mass spectrometry （HPLC-DAD-ESI-MSn） was used to separate and identify the individual chemical components of Citri Reticulatae Folium. As a result, 96 compounds were tentatively identified in this study： including 31 phenolic acids, 4 flavonoid aglycones, 6 flavonoid mono-O-glycosides, 10 flavonoid-O-diglycosides, 5 flavonoid mono-C-glycosides, 5 flavonoid di-C-glycosides, 6 flavonoid O,C-glycosides, 5 （3-hydroxy-3-methylglutaryl） glycosyl flavonoids, 1 flavan-3-ol, and 2 alkaloids. In addition, 21 polymethoxy flavonoids （PMFs） were identified in this paper. Among these compounds, 52 compounds, which were previously found in other Citrus plants, have been identified for the first time in Citri Reticulatae Folium. 15 compounds have not been previously found in the Citrus genus were identified. Moreover, 9 potentially new compounds have also been detected in this paper. This is the first report of the full characterization of chemical components of Citri Reticulatae Folium （leaves of＇Fuju＇） by HPLC-DAD-ESI-MSn.展开更多
基金This research was financially supported by the Citrus Research and Development Foundation(CRDF).
文摘Pathogen-associated molecular patterns(PAMPs)-triggered immunity(PTI)is an important component of plant innate immunity.In a previous study,we showed that the PAMP flg22 from Xanthomonas citri ssp.citri(Xflg22),the causal agent of citrus canker,induced PTI in citrus,which correlated with the observed levels of canker resistance.Here,we identified and sequenced two bacterial flagellin/flg22 receptors(FLS2-1 and FLS2-2)from‘Duncan’grapefruit(Citrus paradisi,CpFLS2-1 and CpFLS2-2)and‘Sun Chu Sha’mandarin(C.reticulata,CrFLS2-1 and CrFLS2-2).We were able to isolate only one FLS2 from‘Nagami’kumquat(Fortunella margarita,FmFLS2-1)and gene flanking sequences suggest a rearrangement event that resulted in the deletion of FLS2-2 from the genome.Phylogenetic analysis,gene structure and presence of critical amino acid domains all indicate we identified the true FLS2 genes in citrus.FLS2-2 was more transcriptionally responsive to Xflg22 than FLS2-1,with induced expression levels higher in canker-resistant citrus than in susceptible ones.Interestingly,‘Nagami’kumquat showed the highest FLS2-1 steady-state expression levels,although it was not induced by Xflg22.We selected FmFLS2-1,CrFLS2-2 and CpFLS2-2 to further evaluate their capacity to enhance bacterial resistance using Agrobacterium-mediated transient expression assays.Both FmFLS2-1 and CrFLS2-2,the two proteins from canker-resistant species,conferred stronger Xflg22 responses and reduced canker symptoms in leaves of the susceptible grapefruit genotype.These two citrus genes will be useful resources to enhance PTI and achieve resistance against canker and possibly other bacterial pathogens in susceptible citrus types.
文摘This study compared the control effect of 110 g/L etoxazole SC,15%abamectin·etoxazole SC,30%cyetpyrafen SC,43%bifenazate SC and 1.8%abamectin EC five acaricides sprayed by unmanned aerial vehicle(UAV)on Panonychus citri,aiming to screen out the appropriate acaricide for the control of this pest by UAV spraying.The results showed that 15%abamectin·etoxazole SC and 30%cyetpyrafen SC had the highest control efficacy,which remained above 90%14 d after application.Secondary performance was observed in 43%bifenazate SC and 110 g/L etoxazole SC,which demonstrated enhancing control effect.However,1.8%abamectin EC showed slower effect.Considering the control effect and population reduction rate of P.citri,15%abamectin·etoxazole SC and 30%cyetpyrafen SC were suggested as the effective acaricides for the control of this pest.
文摘Xcc （Xanthomonas citri subsp, citri） causes citrus bacterial canker, a leaf, stem and fruit spotting disease that affects most commercial citrus species and cultivars. Copper compounds, widely used for management of this pathogen, have been reported as inducers of a VBNC （viable but non-culturable state） in plant pathogenic bacteria. VBNC may be considered as a state preceding bacterial death or as a survival mechanism under adverse conditions. Several experiments were performed to characterize the reversibility and persistence of the VBNC state in Xcc. VBNC was induced in low nutrient medium or with amendment of copper at concentrations used for field disease control. The VBNC condition was demonstrated to persist up to 150 days after copper treatment and was reversed after the addition of culture media without copper or amendment with citrus leaf extract. Xcc viability was evaluated by recovery of colonies on culture media, confirmed by membrane integrity, respiratory activity and by real-time RT-PCR targeting a sequence from the gumD gene. Besides, the colonies recovered were pathogenic on citrus leaves. These results confirm that the VBNC state in Xcc is inducible and reversible and therefore may occur in the phyllosphere when Xcc is under copper stress or starvation.
文摘In order to systematically investigate the chemical constituents of Citri Reticulatae Folium （leaves of ＇Fuju＇）, an analytical method that included high-performance liquid chromatography, diode array detection, electrospray ionization, and ion-trap time-of-flight mass spectrometry （HPLC-DAD-ESI-MSn） was used to separate and identify the individual chemical components of Citri Reticulatae Folium. As a result, 96 compounds were tentatively identified in this study： including 31 phenolic acids, 4 flavonoid aglycones, 6 flavonoid mono-O-glycosides, 10 flavonoid-O-diglycosides, 5 flavonoid mono-C-glycosides, 5 flavonoid di-C-glycosides, 6 flavonoid O,C-glycosides, 5 （3-hydroxy-3-methylglutaryl） glycosyl flavonoids, 1 flavan-3-ol, and 2 alkaloids. In addition, 21 polymethoxy flavonoids （PMFs） were identified in this paper. Among these compounds, 52 compounds, which were previously found in other Citrus plants, have been identified for the first time in Citri Reticulatae Folium. 15 compounds have not been previously found in the Citrus genus were identified. Moreover, 9 potentially new compounds have also been detected in this paper. This is the first report of the full characterization of chemical components of Citri Reticulatae Folium （leaves of＇Fuju＇） by HPLC-DAD-ESI-MSn.
