The aim of the study was to investigate the hepatoprotective effects of Folium syringae(FS) extracts against ethanolinduced acute liver injury. Mice and primary hepatocytes were pretreated with FS extracts at differen...The aim of the study was to investigate the hepatoprotective effects of Folium syringae(FS) extracts against ethanolinduced acute liver injury. Mice and primary hepatocytes were pretreated with FS extracts at different dosages before ethanol administration. Transaminases, glutathione S-transferase A1 level and hepatic biochemical indices(malondialdehyde, superoxide dismutase, glutathione and glutathione peroxidase) were determined. Pretreatment with FS extracts significantly inhibited the damage caused by ethanol and the hepatoprotective effects of FS were almost similar to Silymarin that was used to treat alcoholic liver injury. GSTA1 contents in all the FS extract-treated groups were significantly different from those in the ethanol-induced acute liver injury model group(p<0.01), and similar trends were observed in transaminases and hepatic indices level both in vitro and in vivo. The results showed that FS extracts had hepatoprotective effects against ethanol-induced injury. Those effects might be related to the enhancement of antioxidant capacity of liver cells, and FS extracts could reduce the release of liver GSTA1, which contributed to improve liver detoxification.展开更多
Soybean bacterial spot disease caused by Pseudomonas syringae pv.Glycinea which is a bacterial disease seriously affects soybean yield.Ten soybean germplasms and recombinant inbred lines(RILs)population were used to i...Soybean bacterial spot disease caused by Pseudomonas syringae pv.Glycinea which is a bacterial disease seriously affects soybean yield.Ten soybean germplasms and recombinant inbred lines(RILs)population were used to identify the resistant trait after inoculated with P.sg(P.sgneau001)in this study.High-density genetic mapping was obtained by specific length amplified fragment sequencing(SLAF-seq)of 149 RILs population which was derived from the crossing between Charleston and Dongnong594.The results indicated that 10 germplasm resources had four resistant germplasms included highly resistant cultivar Charleston,four susceptible varieties included Dongnong594 and two moderately resistant cultivars.Five quantitative trait locus(QTLs)were detected in RILs population by the composite interval mapping(CIM)method,and located on Linkage Group(LG)D1b(chromosome two),LG C2(chromosome six)and LG H(chromosome 12),respectively.LOD scores ranged from 2.68 to 4.95 and the phenotypic variation percentage was from 6%to 11%.Six candidate genes were detected,according to the result of gene annotation information.Four of them had relationship with protein kinase activity,protein phosphorylation and leucine rich repeat(LRR)transmembrane protein,which had high expression after inoculated with P.sg by qRT-PCR.展开更多
Mulberry bacterial blight is caused by Pseudomonas syringae pv.mori.Coronatine(COR),a phytotoxin and phytohormone produced by several strains of Pseudomonas syringae,is suggested to have an important role in pathogen-...Mulberry bacterial blight is caused by Pseudomonas syringae pv.mori.Coronatine(COR),a phytotoxin and phytohormone produced by several strains of Pseudomonas syringae,is suggested to have an important role in pathogen-plant interaction.The aim of our study was to examine the influence of COR on mulberry in the process of pathogen infection.Results showed that COR could suppress stomatal closure induced by pathogen-associated molecular patterns(PAMPS),assist pathogenic bacteria into the leaves,and promote bacterial proliferation in the tissues.High-concentration(1 μmol/L) exogenous COR and COR-producing bacterial pathogen induced chlorosis symptom and decrease of chlorophyll content,contrary to the effects of low-concentration(0.001 μmol/L) exogenous COR and non-COR-producing bacterial pathogen.Treatments with COR and DC3000 enhanced the production of reactive oxygen species(ROS),namely,hydrogen peroxide(H_2O_2) and superoxide anion(O_2),but there were two H_2O_2 peaks at 1-3 hpi and 8-24 hpi in the DC3000-treated leaves while only one peak at 1-3 h was observed 1-3 h in the COR-treated ones.H_2O_2 could kill the pathogenic bacteria,on the other hand,it also acted as an upstream signaling molecule to promote nitric oxide(NO) production to further participate in the signaling pathway.Enzymatic antioxidant systems(superoxide dismutase,peroxidase and catalase) and defensive enzyme systems(lipoxygenase,polyphenol oxidase and phenylalnine ammonialyase) were activated by COR.Therefore,COR could cooperate on the invasion and proliferation of COR-producing bacterial pathogens,and induce the chlorosis symptom in mulberry.At the same time,exogenously applied COR also could enhance the resistance to P.syringae pv.mori by production of signal molecules to activate signaling pathway and promoting defense-related metabolism.展开更多
Some Pseudomonas syringae pathovars secrete tabtoxin, a monocyclic β-lactam antibiotic, responsible for chlorosis, the principal halo blight symptom in susceptible plants as oats, rye, barley, wheat and sorghum, amon...Some Pseudomonas syringae pathovars secrete tabtoxin, a monocyclic β-lactam antibiotic, responsible for chlorosis, the principal halo blight symptom in susceptible plants as oats, rye, barley, wheat and sorghum, among other. Here, we demonstrated that the production of tabtoxin in a P. syringae strain increased at least 150%, when choline, betaine or dimethylglycine were used as nitrogen source, or when choline was added as osmoprotectant in hyperosmolar culture media. Besides, we investigated the induction of phosphorylcholine phosphatase (PchP) activity when choline or its metabolites were used as nitrogen sources. PchP is an enzyme involved in Pseudomonas aeruginosa pathogenesis through its contribution to the breakdown of choline-containing compounds of the host cells. Considering these results and that the success of a pathogenic microorganism depends on its ability to survive and proliferate in its target tissue, we propose that choline is one of the plant signals that contribute to establishment of the infection by tabtoxin-producing strains of P. syringae.展开更多
Pseudomonas syringae pv.actinidiae(Psa)causes bacterial canker,a devastating disease threatening the Actinidia fruit industry.In a search for non-host resistance genes against Psa,we find that the nucleotidebinding le...Pseudomonas syringae pv.actinidiae(Psa)causes bacterial canker,a devastating disease threatening the Actinidia fruit industry.In a search for non-host resistance genes against Psa,we find that the nucleotidebinding leucine-rich repeat receptor(NLR)protein ZAR1 from both Arabidopsis and Nicotiana benthamiana(Nb)recognizes Hop Z5 and triggers cell death.The recognition requires ZED1 in Arabidopsis and JIM2 in Nb plants,which are members of the ZRK pseudokinases and known components of the ZAR1 resistosome.Surprisingly,Arabidopsis ZAR1 and RPM1,another NLR known to recognize Hop Z5,confer disease resistance to Hop Z5 in a strain-specific manner.Thus,ZAR1,but not RPM1,is solely required for resistance to P.s.maculicola ES4326(Psm)carrying hop Z5,whereas RPM1 is primarily required for resistance to P.s.tomato DC3000(Pst)carrying hop Z5.Furthermore,the ZAR1-mediated resistance to Psm hop Z5 in Arabidopsis is insensitive to SOBER1,which encodes a deacetylase known to suppress the RPM1-mediated resistance to Pst hop Z5.In addition,hop Z5 enhances P.syringae virulence in the absence of ZAR1 or RPM1 and that SOBER1 abolishes such virulence function.Together the study suggests that ZAR1 may be used for improving Psa resistance in Actinidia and uncovers previously unknown complexity of effectortriggered immunity and effector-triggered virulence.展开更多
Rice bacterial leaf brown spot disease caused by Pseudomonas syringae pv.syringae(Pss)is a major disease on rice.In recent years,Pss has emerged worldwide,seriously affecting rice production.It is very important to es...Rice bacterial leaf brown spot disease caused by Pseudomonas syringae pv.syringae(Pss)is a major disease on rice.In recent years,Pss has emerged worldwide,seriously affecting rice production.It is very important to establish a rapid detection method of Pss for the diagnosis and prevention of this disease.In order to robust and accurately diagnose the rice bacterial leaf brown spot disease in the field and laboratory,an assay system for the Pss was developed in this study,and the specific sequence of hrcN was used as the target,based on loop-mediated isothermal amplification(LAMP).The best detection system was MgSO 48 mmol·L^(-1),Bst DNA polymerase 8 U,dNTP 1.4 mmol·L^(-1),the ratio of internal and outer primers was 2:1,the reaction temperature was 63℃,the reaction time was 45 min,and the lowest sensitivity was 104 CFU·mL^(-1).This results provided an accurate and robust method for laboratory and field diagnosis of bacterial leaf brown spot disease of rice.展开更多
Kiwifruit canker disease seriously affects the yield and quality of"Guichang"kiwifruit in Xiuwen County,Guizhou Province.In order to scientifically,safely,greenly and efficiently prevent and control the dise...Kiwifruit canker disease seriously affects the yield and quality of"Guichang"kiwifruit in Xiuwen County,Guizhou Province.In order to scientifically,safely,greenly and efficiently prevent and control the disease,theory was combined with prevention and control techniques to optimize existing prevention and control techniques,so as to improve the production yield and quality of kiwifruit.Specifically,biocontrol strains targeting local kiwifruit canker disease were screened,and reduced and mixed use of agrochemicals with improved efficiency was studied;and the effects and application techniques of disease resistance inducers and bioorganic fertilizers in inducing systemic disease resistance in kiwifruit trees were explored,and finally,an integrated green prevention and control scheme for kiwifruit canker disease that is suitable for kiwifruit production areas in Guizhou Province and has strong operability was proposed.This study provides technical support for green,efficient,standardized production technical services and sustainable and healthy development of kiwifruit industry.展开更多
Through the survey of current situation of application of Syringa in Beijing City, the paper concluded the collocation method of Syringa, and proposed some suggestions on the application of Syringa in Beijing City in ...Through the survey of current situation of application of Syringa in Beijing City, the paper concluded the collocation method of Syringa, and proposed some suggestions on the application of Syringa in Beijing City in future.展开更多
The potential of Garcinia mangostana as a biological control agent against plant pathogenic bacteria which decrease the quality and volume of crop production worldwide was assessed. Mangosteen leaves were extracted by...The potential of Garcinia mangostana as a biological control agent against plant pathogenic bacteria which decrease the quality and volume of crop production worldwide was assessed. Mangosteen leaves were extracted by maceration using chloroform, n-hexane, and methanol. For the in vitro antibacterial activity, two dissimilar species of plant pathogenic bacteria: Pseudomonas syringe pv. tomato and Xanthomonas oryzae pv. oryzae were acquired. Four different concentrations, 12.5, 25, 50, and 100 mg/ml were obtained through the cup-plate agar diffusion technique. Streptomycin sulphate at 30 μg/ml concentration was set as the positive control, whereas every respective solvent used in the leaf extraction was set as the negative control. The results have shown that, only methanol extract demonstrated antibacterial activity when tested on the plant pathogenic bacteria. The highest diameter of inhibition zones was observed in X. oryzae pv. oryzae, at all range of concentrations, followed by P. syringae pv. tomato. The least methanol extract concentration utilised in determination of minimum inhibitory concentration (MIC) assay was at 1.562 mg/ml, inhibiting X. oryzae pv. oryzae, followed by P. syringe pv. tomato at a concentration 3.125 mg/ml. Antibacterial impacts of the most effectual extract of mangosteen crude were supported by the existence of chemical components identified by GC-MS. Cycloartenol, Caryophyllene, Docosane, Phenol, 4,4-Methylenebis (2,6-di-tert-butylphenol) and Chromium were noted as key compounds in the mangosteen leaf extract, which were perhaps causing the antibacterial activity.展开更多
Syringa species not only have good ornamental properties but also play an important role in the landscaping and environmental purification of cities.To investigate the chilling stress resistance of Syringa oblata Lind...Syringa species not only have good ornamental properties but also play an important role in the landscaping and environmental purification of cities.To investigate the chilling stress resistance of Syringa oblata Lindl.and Syringa reticulata var.mandshurica and provide theoretical grounds for the practical cultivation of Syringa species,in vitro leaves were used to study photosynthetic gas exchange parameters and chlorophyll fluorescence parameters.After nine hours of chilling,decreasing rates of net photosynthesis,stomatal conductance,and transpiration in S.reticulata var.mandshurica leaves were significantly greater than that of the S.oblata,while intercellular CO2 concentrations in S.oblata leaves were higher than those in S.reticulata var.mandshurica.The quantum yield of PSII reaction center(APSII)declined in S.reticulata and light capture efficiency(Fv 0/Fm 0)was stable.However,reduction percentages of Fv 0/Fm 0,APSII,and Fv/Fm in S.oblata were significant higher than those of S.reticulata var.mandshurica.After nine hours of chilling,the relative variable fluorescence of VJ and VI of S.oblata increased and the increasing rate of VJ was greater than VI.In contrast,the change of VJ and VI in S.reticulata var.mandshurica leaves was relatively small.This suggests that chilling primarily damaged the electron transport process of QA to QB at the receptor site of the PSII reaction center.Photosynthetic capacity of S.oblata was more sensitive to chilling stress compared to S.reticulate var.mandshurica,which the limitations were mainly due to non-stomatal factors such as the decrease in electron transport efficiency,activity in the PSII reaction center,and the destruction of the photodamage defense system.展开更多
基金Supported by the National Natural Science Foundation of China(31472241)the Application Technology Research and Development Projects in Heilongjiang Province of China(PC13S03)
文摘The aim of the study was to investigate the hepatoprotective effects of Folium syringae(FS) extracts against ethanolinduced acute liver injury. Mice and primary hepatocytes were pretreated with FS extracts at different dosages before ethanol administration. Transaminases, glutathione S-transferase A1 level and hepatic biochemical indices(malondialdehyde, superoxide dismutase, glutathione and glutathione peroxidase) were determined. Pretreatment with FS extracts significantly inhibited the damage caused by ethanol and the hepatoprotective effects of FS were almost similar to Silymarin that was used to treat alcoholic liver injury. GSTA1 contents in all the FS extract-treated groups were significantly different from those in the ethanol-induced acute liver injury model group(p<0.01), and similar trends were observed in transaminases and hepatic indices level both in vitro and in vivo. The results showed that FS extracts had hepatoprotective effects against ethanol-induced injury. Those effects might be related to the enhancement of antioxidant capacity of liver cells, and FS extracts could reduce the release of liver GSTA1, which contributed to improve liver detoxification.
基金Supported by the National Key R&D Program of China(2016YFD0100201)Science Foundation for Distinguished Young Scholars of Heilongjiang Province(JC2016004)Harbin Science Technology Project(2015RQXXJ018)。
文摘Soybean bacterial spot disease caused by Pseudomonas syringae pv.Glycinea which is a bacterial disease seriously affects soybean yield.Ten soybean germplasms and recombinant inbred lines(RILs)population were used to identify the resistant trait after inoculated with P.sg(P.sgneau001)in this study.High-density genetic mapping was obtained by specific length amplified fragment sequencing(SLAF-seq)of 149 RILs population which was derived from the crossing between Charleston and Dongnong594.The results indicated that 10 germplasm resources had four resistant germplasms included highly resistant cultivar Charleston,four susceptible varieties included Dongnong594 and two moderately resistant cultivars.Five quantitative trait locus(QTLs)were detected in RILs population by the composite interval mapping(CIM)method,and located on Linkage Group(LG)D1b(chromosome two),LG C2(chromosome six)and LG H(chromosome 12),respectively.LOD scores ranged from 2.68 to 4.95 and the phenotypic variation percentage was from 6%to 11%.Six candidate genes were detected,according to the result of gene annotation information.Four of them had relationship with protein kinase activity,protein phosphorylation and leucine rich repeat(LRR)transmembrane protein,which had high expression after inoculated with P.sg by qRT-PCR.
基金Supported by the Science and Technology Support Program of the Jiangsu Province(BE2012365)the Modern Agro-industry Technology Research System of China(CARS-22)
文摘Mulberry bacterial blight is caused by Pseudomonas syringae pv.mori.Coronatine(COR),a phytotoxin and phytohormone produced by several strains of Pseudomonas syringae,is suggested to have an important role in pathogen-plant interaction.The aim of our study was to examine the influence of COR on mulberry in the process of pathogen infection.Results showed that COR could suppress stomatal closure induced by pathogen-associated molecular patterns(PAMPS),assist pathogenic bacteria into the leaves,and promote bacterial proliferation in the tissues.High-concentration(1 μmol/L) exogenous COR and COR-producing bacterial pathogen induced chlorosis symptom and decrease of chlorophyll content,contrary to the effects of low-concentration(0.001 μmol/L) exogenous COR and non-COR-producing bacterial pathogen.Treatments with COR and DC3000 enhanced the production of reactive oxygen species(ROS),namely,hydrogen peroxide(H_2O_2) and superoxide anion(O_2),but there were two H_2O_2 peaks at 1-3 hpi and 8-24 hpi in the DC3000-treated leaves while only one peak at 1-3 h was observed 1-3 h in the COR-treated ones.H_2O_2 could kill the pathogenic bacteria,on the other hand,it also acted as an upstream signaling molecule to promote nitric oxide(NO) production to further participate in the signaling pathway.Enzymatic antioxidant systems(superoxide dismutase,peroxidase and catalase) and defensive enzyme systems(lipoxygenase,polyphenol oxidase and phenylalnine ammonialyase) were activated by COR.Therefore,COR could cooperate on the invasion and proliferation of COR-producing bacterial pathogens,and induce the chlorosis symptom in mulberry.At the same time,exogenously applied COR also could enhance the resistance to P.syringae pv.mori by production of signal molecules to activate signaling pathway and promoting defense-related metabolism.
文摘Some Pseudomonas syringae pathovars secrete tabtoxin, a monocyclic β-lactam antibiotic, responsible for chlorosis, the principal halo blight symptom in susceptible plants as oats, rye, barley, wheat and sorghum, among other. Here, we demonstrated that the production of tabtoxin in a P. syringae strain increased at least 150%, when choline, betaine or dimethylglycine were used as nitrogen source, or when choline was added as osmoprotectant in hyperosmolar culture media. Besides, we investigated the induction of phosphorylcholine phosphatase (PchP) activity when choline or its metabolites were used as nitrogen sources. PchP is an enzyme involved in Pseudomonas aeruginosa pathogenesis through its contribution to the breakdown of choline-containing compounds of the host cells. Considering these results and that the success of a pathogenic microorganism depends on its ability to survive and proliferate in its target tissue, we propose that choline is one of the plant signals that contribute to establishment of the infection by tabtoxin-producing strains of P. syringae.
基金supported by grants from the National Key R&D Program of China (2021YFA1300701) to J.M.Z.the National Natural Science Foundation of China (31872654) to Z.Y.Z.the Hainan Excellent Talent Team, and the State Key Laboratory of Plant Genomics (SKLPG2016B-2) to J.M.Z
文摘Pseudomonas syringae pv.actinidiae(Psa)causes bacterial canker,a devastating disease threatening the Actinidia fruit industry.In a search for non-host resistance genes against Psa,we find that the nucleotidebinding leucine-rich repeat receptor(NLR)protein ZAR1 from both Arabidopsis and Nicotiana benthamiana(Nb)recognizes Hop Z5 and triggers cell death.The recognition requires ZED1 in Arabidopsis and JIM2 in Nb plants,which are members of the ZRK pseudokinases and known components of the ZAR1 resistosome.Surprisingly,Arabidopsis ZAR1 and RPM1,another NLR known to recognize Hop Z5,confer disease resistance to Hop Z5 in a strain-specific manner.Thus,ZAR1,but not RPM1,is solely required for resistance to P.s.maculicola ES4326(Psm)carrying hop Z5,whereas RPM1 is primarily required for resistance to P.s.tomato DC3000(Pst)carrying hop Z5.Furthermore,the ZAR1-mediated resistance to Psm hop Z5 in Arabidopsis is insensitive to SOBER1,which encodes a deacetylase known to suppress the RPM1-mediated resistance to Pst hop Z5.In addition,hop Z5 enhances P.syringae virulence in the absence of ZAR1 or RPM1 and that SOBER1 abolishes such virulence function.Together the study suggests that ZAR1 may be used for improving Psa resistance in Actinidia and uncovers previously unknown complexity of effectortriggered immunity and effector-triggered virulence.
基金Supported by the Natural Science Foundation of Heilongjiang Province(Topic C2017032)Heilongjiang Province Applied Technology Research and Development Program(Topic GA19B104)the National Key Research and Development Program(Topic 2018YFD0300105)。
文摘Rice bacterial leaf brown spot disease caused by Pseudomonas syringae pv.syringae(Pss)is a major disease on rice.In recent years,Pss has emerged worldwide,seriously affecting rice production.It is very important to establish a rapid detection method of Pss for the diagnosis and prevention of this disease.In order to robust and accurately diagnose the rice bacterial leaf brown spot disease in the field and laboratory,an assay system for the Pss was developed in this study,and the specific sequence of hrcN was used as the target,based on loop-mediated isothermal amplification(LAMP).The best detection system was MgSO 48 mmol·L^(-1),Bst DNA polymerase 8 U,dNTP 1.4 mmol·L^(-1),the ratio of internal and outer primers was 2:1,the reaction temperature was 63℃,the reaction time was 45 min,and the lowest sensitivity was 104 CFU·mL^(-1).This results provided an accurate and robust method for laboratory and field diagnosis of bacterial leaf brown spot disease of rice.
基金Supported by Science and Technology Support Program of Guizhou Province(QKHZC[2020]1Y135)General Higher Education Science and Technology Top-notch Talents Project of Guizhou Province(QJH KY Z[2021]037)+5 种基金Science and Technology Program of Guizhou Province(QKHJZ-ZK[2022]ZD 025)High-level Talent Scientific Research Startup Project of Guizhou Institute of Technology(XJGC20190632)Earth Thesis Project of Guizhou Institute of Technology(KJZX20-005)High-Level Talent Initial Funding of Guizhou Industry Polytechnic College(2023-RC-01)Enterprise Commissioned Project of Guizhou Industrial Polytechnic College(2023-HX-01)Enterprise Commissioned Project of Guizhou Industrial Polytechnic College(2023-HX-02).
文摘Kiwifruit canker disease seriously affects the yield and quality of"Guichang"kiwifruit in Xiuwen County,Guizhou Province.In order to scientifically,safely,greenly and efficiently prevent and control the disease,theory was combined with prevention and control techniques to optimize existing prevention and control techniques,so as to improve the production yield and quality of kiwifruit.Specifically,biocontrol strains targeting local kiwifruit canker disease were screened,and reduced and mixed use of agrochemicals with improved efficiency was studied;and the effects and application techniques of disease resistance inducers and bioorganic fertilizers in inducing systemic disease resistance in kiwifruit trees were explored,and finally,an integrated green prevention and control scheme for kiwifruit canker disease that is suitable for kiwifruit production areas in Guizhou Province and has strong operability was proposed.This study provides technical support for green,efficient,standardized production technical services and sustainable and healthy development of kiwifruit industry.
文摘Through the survey of current situation of application of Syringa in Beijing City, the paper concluded the collocation method of Syringa, and proposed some suggestions on the application of Syringa in Beijing City in future.
文摘The potential of Garcinia mangostana as a biological control agent against plant pathogenic bacteria which decrease the quality and volume of crop production worldwide was assessed. Mangosteen leaves were extracted by maceration using chloroform, n-hexane, and methanol. For the in vitro antibacterial activity, two dissimilar species of plant pathogenic bacteria: Pseudomonas syringe pv. tomato and Xanthomonas oryzae pv. oryzae were acquired. Four different concentrations, 12.5, 25, 50, and 100 mg/ml were obtained through the cup-plate agar diffusion technique. Streptomycin sulphate at 30 μg/ml concentration was set as the positive control, whereas every respective solvent used in the leaf extraction was set as the negative control. The results have shown that, only methanol extract demonstrated antibacterial activity when tested on the plant pathogenic bacteria. The highest diameter of inhibition zones was observed in X. oryzae pv. oryzae, at all range of concentrations, followed by P. syringae pv. tomato. The least methanol extract concentration utilised in determination of minimum inhibitory concentration (MIC) assay was at 1.562 mg/ml, inhibiting X. oryzae pv. oryzae, followed by P. syringe pv. tomato at a concentration 3.125 mg/ml. Antibacterial impacts of the most effectual extract of mangosteen crude were supported by the existence of chemical components identified by GC-MS. Cycloartenol, Caryophyllene, Docosane, Phenol, 4,4-Methylenebis (2,6-di-tert-butylphenol) and Chromium were noted as key compounds in the mangosteen leaf extract, which were perhaps causing the antibacterial activity.
文摘Syringa species not only have good ornamental properties but also play an important role in the landscaping and environmental purification of cities.To investigate the chilling stress resistance of Syringa oblata Lindl.and Syringa reticulata var.mandshurica and provide theoretical grounds for the practical cultivation of Syringa species,in vitro leaves were used to study photosynthetic gas exchange parameters and chlorophyll fluorescence parameters.After nine hours of chilling,decreasing rates of net photosynthesis,stomatal conductance,and transpiration in S.reticulata var.mandshurica leaves were significantly greater than that of the S.oblata,while intercellular CO2 concentrations in S.oblata leaves were higher than those in S.reticulata var.mandshurica.The quantum yield of PSII reaction center(APSII)declined in S.reticulata and light capture efficiency(Fv 0/Fm 0)was stable.However,reduction percentages of Fv 0/Fm 0,APSII,and Fv/Fm in S.oblata were significant higher than those of S.reticulata var.mandshurica.After nine hours of chilling,the relative variable fluorescence of VJ and VI of S.oblata increased and the increasing rate of VJ was greater than VI.In contrast,the change of VJ and VI in S.reticulata var.mandshurica leaves was relatively small.This suggests that chilling primarily damaged the electron transport process of QA to QB at the receptor site of the PSII reaction center.Photosynthetic capacity of S.oblata was more sensitive to chilling stress compared to S.reticulate var.mandshurica,which the limitations were mainly due to non-stomatal factors such as the decrease in electron transport efficiency,activity in the PSII reaction center,and the destruction of the photodamage defense system.
