Nostoc flagelliforme is a terrestrial cyanobacterium that can resist many types of stressors,including drought,ultraviolet radiation,and extreme temperatures.In this study,we identified the drought tolerance gene Nfcr...Nostoc flagelliforme is a terrestrial cyanobacterium that can resist many types of stressors,including drought,ultraviolet radiation,and extreme temperatures.In this study,we identified the drought tolerance gene NfcrtO,which encodes aβ-carotene ketolase,through screening the transcriptome of N.flagelliforme under water loss stress.Prokaryotic expression of NfcrtO under 0.6 mol/L sorbitol or under 0.3 mol/L NaCl stress significantly increased the growth rate of Escherichia coli.When NfcrtO was heterologously expressed in rice,the seedling height and root length of NfcrtO-overexpressing rice plants were significantly higher than those of the wild type(WT)plants grown on½Murashige and Skoog solid medium with 120 mmol/L mannitol at the seedling stage.Transcriptome analysis revealed that NfcrtO was involved in osmotic stress,antioxidant,and other stress-related pathways.Additionally,the survival rate of the NfcrtO-overexpression lines was significantly higher than that of the WT line under both hydroponic stress(24%PEG and 100 mmol/L H_(2)O_(2))and soil drought treatment at the seedling stage.Physiological traits,including the activity levels of superoxide dismutase,peroxidase,catalase,total antioxidant capacity,and the contents of proline,trehalose,and soluble sugar,were significantly improved in the NfcrtO-overexpression lines relative to those in the WT line under 20%PEG treatment.Furthermore,when water was withheld at the booting stage,the grain yield per plant of NfcrtO-overexpression lines was significantly higher than that of the WT line.Yeast two-hybrid analysis identified interactions between NfcrtO and Dna J protein,E3 ubiquitin-protein ligase,and pyrophosphate-energized vacuolar membrane proton pump.Thus,heterologous expression of NfcrtO in rice could significantly improve the tolerance of rice to osmotic stress,potentially facilitating the development of new rice varieties.展开更多
Dehydrins(DHNs),as members of the late embryogenesis abundant protein family,play critical roles in the protection of seeds from dehydration and plant adaptation to multiple abiotic stresses.Vitrification is a basic m...Dehydrins(DHNs),as members of the late embryogenesis abundant protein family,play critical roles in the protection of seeds from dehydration and plant adaptation to multiple abiotic stresses.Vitrification is a basic method in plant cryopreservation and is characterized by forming a glassy state to prevent lethal ice crystals produced during cryogenic storage.In this study,ApSK3 type DHN was genetically transformed into embryogenic calluses(EC)of Agapanthus praecox by overexpression(OE)and RNA interference(RNAi)techniques to evaluate the in vivo protective effect of DHNs during cryopreservation.The cell viability showed a completely opposite trend in OE and RNAi cell lines,the cell relative death ratio was decreased by 20.0%in ApSK3-OE EC and significantly increased by 66.15%in ApSK3-RNAi cells after cryopreservation.Overexpression of ApSK3 increased the content of non-enzymatic antioxidants(AsA and GSH)and up-regulated the expression of CAT,SOD,POD,and GPX genes,while ApSK3-RNAi cells decreased antioxidant enzyme activities and FeSOD,POD,and APX genes expression during cryopreservation.These findings suggest that ApSK3 affects ROS metabolism through chelating metal ions(Cu^(2+)and Fe^(3+)),alleviates H_(2)O_(2)and OH·excessive generation,activates the antioxidant system,and improves cellular REDOX balance and membrane lipid peroxidation damage of plant cells during cryopreservation.DHNs can effectively improve cell stress tolerance and have great potential for in vivo or in vitro applications in plant cryopreservation.展开更多
Many current studies on rapid detection of pathogenic bacteria in foods have focused on the construction of detection methods,neglecting pretreatment.It is also a key step to efficiently elute pathogenic bacteria from...Many current studies on rapid detection of pathogenic bacteria in foods have focused on the construction of detection methods,neglecting pretreatment.It is also a key step to efficiently elute pathogenic bacteria from food samples for rapid detection and can even determine the success or failure of an assay.In this study,we used Escherichia coli(E.coli),Salmonella enteritidis(S.enteritidis),and Listeria monocytogenes(L.monocytogenes)as model bacteria to compare the elution efficiency of different eluants;explore the effect of surfactant,ionic strength,protein(or amino acid and peptide),and enzyme on the recovery rate of bacteria in lettuce;and compare the compound effect caused by multiple factors.Finally,we developed an efficient bacterial recovery method and confirmed the superiority of this method to analyze the bacterial diversity of eluants from lettuce.The results showed that the recovery efficiency of E.coli,S.enteritidis,and L.monocytogenes,which were artificially contaminated with approximately 10^(5)CFU/g in lettuces,could reach 94.4%,90.6%,and 93.7%by using 10 mmol/L Tris·HCl(pH 9.5)with 0.1%peptone and 300 U/100 mL of cellulase,and furthermore,the elution efficiency could reach 99.6%,98.6%,and 100%with the aid of a 2-min stomaching.For the lettuce samples with only native bacteria,the recovery rate reached 92.1%for viable aerobic bacteria by this method,which was approximately 10%higher than that of the modified previous method.The bacterial diversity of the eluted solution was analyzed,and the result was significantly improved.Considering these advantages,it is important to improve the elution efficiency to achieve rapid and accurate detection of pathogenic bacteria in lettuces.展开更多
基金supported by the National Key Research and Development Program of China(Grant No.2018YFE0106200)the Science and Technology Research Project of Jiangxi Provincial Department of Education,China(Grant No.K4100131)the Science and Technology Research Project of Shangrao,Jiangxi Province,China(Grant No.K4000019).
文摘Nostoc flagelliforme is a terrestrial cyanobacterium that can resist many types of stressors,including drought,ultraviolet radiation,and extreme temperatures.In this study,we identified the drought tolerance gene NfcrtO,which encodes aβ-carotene ketolase,through screening the transcriptome of N.flagelliforme under water loss stress.Prokaryotic expression of NfcrtO under 0.6 mol/L sorbitol or under 0.3 mol/L NaCl stress significantly increased the growth rate of Escherichia coli.When NfcrtO was heterologously expressed in rice,the seedling height and root length of NfcrtO-overexpressing rice plants were significantly higher than those of the wild type(WT)plants grown on½Murashige and Skoog solid medium with 120 mmol/L mannitol at the seedling stage.Transcriptome analysis revealed that NfcrtO was involved in osmotic stress,antioxidant,and other stress-related pathways.Additionally,the survival rate of the NfcrtO-overexpression lines was significantly higher than that of the WT line under both hydroponic stress(24%PEG and 100 mmol/L H_(2)O_(2))and soil drought treatment at the seedling stage.Physiological traits,including the activity levels of superoxide dismutase,peroxidase,catalase,total antioxidant capacity,and the contents of proline,trehalose,and soluble sugar,were significantly improved in the NfcrtO-overexpression lines relative to those in the WT line under 20%PEG treatment.Furthermore,when water was withheld at the booting stage,the grain yield per plant of NfcrtO-overexpression lines was significantly higher than that of the WT line.Yeast two-hybrid analysis identified interactions between NfcrtO and Dna J protein,E3 ubiquitin-protein ligase,and pyrophosphate-energized vacuolar membrane proton pump.Thus,heterologous expression of NfcrtO in rice could significantly improve the tolerance of rice to osmotic stress,potentially facilitating the development of new rice varieties.
基金This work was supported by the National Natural Science Foundation of China[Grant Nos.31870686,31971705,and 31670693]the Natural Science Foundation of Shanghai[Grant No.21ZR1434200].
文摘Dehydrins(DHNs),as members of the late embryogenesis abundant protein family,play critical roles in the protection of seeds from dehydration and plant adaptation to multiple abiotic stresses.Vitrification is a basic method in plant cryopreservation and is characterized by forming a glassy state to prevent lethal ice crystals produced during cryogenic storage.In this study,ApSK3 type DHN was genetically transformed into embryogenic calluses(EC)of Agapanthus praecox by overexpression(OE)and RNA interference(RNAi)techniques to evaluate the in vivo protective effect of DHNs during cryopreservation.The cell viability showed a completely opposite trend in OE and RNAi cell lines,the cell relative death ratio was decreased by 20.0%in ApSK3-OE EC and significantly increased by 66.15%in ApSK3-RNAi cells after cryopreservation.Overexpression of ApSK3 increased the content of non-enzymatic antioxidants(AsA and GSH)and up-regulated the expression of CAT,SOD,POD,and GPX genes,while ApSK3-RNAi cells decreased antioxidant enzyme activities and FeSOD,POD,and APX genes expression during cryopreservation.These findings suggest that ApSK3 affects ROS metabolism through chelating metal ions(Cu^(2+)and Fe^(3+)),alleviates H_(2)O_(2)and OH·excessive generation,activates the antioxidant system,and improves cellular REDOX balance and membrane lipid peroxidation damage of plant cells during cryopreservation.DHNs can effectively improve cell stress tolerance and have great potential for in vivo or in vitro applications in plant cryopreservation.
基金supported by Shanghai‘Science and Technology Innovation Action Plan’for Agriculture Project(19391902100,21N31901100)the Special Project on Agricultural Science and Technology Innovation—Applied Basic Research Project of Shanghai Academy of Agricultural Sciences(Agricultural Science Application Foundation 2022-09),China.
文摘Many current studies on rapid detection of pathogenic bacteria in foods have focused on the construction of detection methods,neglecting pretreatment.It is also a key step to efficiently elute pathogenic bacteria from food samples for rapid detection and can even determine the success or failure of an assay.In this study,we used Escherichia coli(E.coli),Salmonella enteritidis(S.enteritidis),and Listeria monocytogenes(L.monocytogenes)as model bacteria to compare the elution efficiency of different eluants;explore the effect of surfactant,ionic strength,protein(or amino acid and peptide),and enzyme on the recovery rate of bacteria in lettuce;and compare the compound effect caused by multiple factors.Finally,we developed an efficient bacterial recovery method and confirmed the superiority of this method to analyze the bacterial diversity of eluants from lettuce.The results showed that the recovery efficiency of E.coli,S.enteritidis,and L.monocytogenes,which were artificially contaminated with approximately 10^(5)CFU/g in lettuces,could reach 94.4%,90.6%,and 93.7%by using 10 mmol/L Tris·HCl(pH 9.5)with 0.1%peptone and 300 U/100 mL of cellulase,and furthermore,the elution efficiency could reach 99.6%,98.6%,and 100%with the aid of a 2-min stomaching.For the lettuce samples with only native bacteria,the recovery rate reached 92.1%for viable aerobic bacteria by this method,which was approximately 10%higher than that of the modified previous method.The bacterial diversity of the eluted solution was analyzed,and the result was significantly improved.Considering these advantages,it is important to improve the elution efficiency to achieve rapid and accurate detection of pathogenic bacteria in lettuces.
