Exogenous proline is an effective agent for increasing plant tolerance to abiotic stress in plants. In this study, we evaluated its effect on seedlings of Siete Caldos chili pepper (Capsicum frutescens), a semi-domest...Exogenous proline is an effective agent for increasing plant tolerance to abiotic stress in plants. In this study, we evaluated its effect on seedlings of Siete Caldos chili pepper (Capsicum frutescens), a semi-domesticated variety. The Capsicum genus is known for its sensitivity to water stress. We pretreated the seedlings’ roots by immersing them in proline solutions (0, 2.5, 5, 7.5, and 10 mM) for 48 h. Then, we exposed them to water stress using a Hoagland nutrient solution supplemented with 10% polyethylene glycol (PEG-8000) for nine days. We analyzed key physiological and biochemical parameters, including relative water content, cell membrane stability index, electrolyte leakage, chlorophyll, and proline content. The results indicated that proline concentrations of 2.5 and 5 mM significantly increased tolerance to water stress, with 100% survival. These seedlings maintained greater hydration and cell membrane stability compared to non-pretreated seedlings. In contrast, at the highest concentrations (7.5 and 10 mM Pro), survival was 63.63% and 54.54%, respectively. This study demonstrated that exogenous proline enhances water stress tolerance in Capsicum frutescens seedlings by mitigating the negative impact on physiological and biochemical processes vital for survival. This theoretical foundation can be applied to improve chili seedling performance in controlled production environments.展开更多
High nitrate(NO3-) in vegetables, especially in leaf vegetables poses threaten to human health. Selenium(Se) is an important element for maintaining human health, and exogenous Se application during vegetable and crop...High nitrate(NO3-) in vegetables, especially in leaf vegetables poses threaten to human health. Selenium(Se) is an important element for maintaining human health, and exogenous Se application during vegetable and crop production is an effective way to prevent Se deficiency in human bodies. Exogenous Se shows positive function on plant growth and nutrition uptake under abiotic and/or biotic stresses. However, the influence of exogenous Se on NO3-accumulation in hydroponic vegetables is still not clear. In the present study, hydroponic lettuce plants were subjected to six different concentrations(0, 0.1, 0.5, 5, 10 and 50 μmol L–1) of Se as Na2 Se O3. The effects of Se on NO3-content, plant growth, and photosynthetic capacity of lettuce(Lactuca sativa L.) were investigated. The results showed that exogenous Se positively decreased NO3-content and this effect was concentration-dependent. The lowest NO3-content was obtained under 0.5 μmol L–1 Se treatment. The application of Se enhanced photosynthetic capacity by increasing the photosynthesis rate(Pn), stomatal conductance(Cs) and the transpiration efficiency(Tr) of lettuce. The transportation and assimilation of NO3-and activities of nitrogen metabolism enzymes in lettuce were also analysed. The NO3-efflux in the lettuce roots was markedly increased, but the efflux of NO3-from the root to the shoot was decreased after treated with exogenous Se. Moreover, Se application stimulated NO3-assimilation by enhancing nitrate reductase(NR), nitrite reductase(Ni R), glutamine synthetase(GS) and glutamate synthase enzyme(GOGAT) activities. These results provide direct evidence that exogenous Se shows positive function on decreasing NO3-accumulation via regulating the transport and enhancing activities of nitrogen metabolism enzyme in lettuce. We suggested that 0.5 μmol L–1 Se can be used to reduce NO3-content and increase hydroponic lettuce yield.展开更多
The galvanic corrosion of the Q-phase/Al couple in 0.1 M NaCl solutions has been studied using the scanning vibrating electrode technique (SVET)f the scanning ion-selective electrode technique (SIET) and energy disper...The galvanic corrosion of the Q-phase/Al couple in 0.1 M NaCl solutions has been studied using the scanning vibrating electrode technique (SVET)f the scanning ion-selective electrode technique (SIET) and energy dispersive X-ray spectroscopy (EDX). The galvanic corrosion of the Q-phase/Al couple was found to be dependent on pH and immersion time. Current density maps obtained by SVET shows that the anodic oxidation processes emerge from Al in a localized manner in pH 2 and 6 solutions but is initiated in a uniform manner in pH 13 solution, whereas, the cathodic processes are more homogeneously distributed over the Q-phase at pH 2.6 and 13. It is seen that the Q-phase remains cathodic in the Q-phase/Al couple in acidic, neutral and alkaline solutions indicating that the galvanic polarity of the Q-phase is independent of pH. The effect of the galvanic corrosion was largest at pH 2 and 13 compared to pH 6. The pH map obtained by SIET indicates that the galvanic activity of the Q-phase/Al couple proceeds via heavy alkalization of the Q-phase surface with the generation of appreciable amounts of OH~ ions. The enrichment of Cu indicated by EDX is responsible for the observed cathodic activity of the Q-phase in the Q-phase/Al couple.展开更多
The study of corrosion of magnesium and its alloys has emerged a hot topic in the applications of lightweight structural materials. The inherently high electrochemical activity of bare magnesium surfaces still lacks a...The study of corrosion of magnesium and its alloys has emerged a hot topic in the applications of lightweight structural materials. The inherently high electrochemical activity of bare magnesium surfaces still lacks a convincing mechanism to describe the observed experimental characteristics, and it has prompted the development of various types of protective coatings with the aim of slowing metal dissolution. In recent years, new instruments and techniques have been developed to study with spatial resolution the local corrosion processes that occur in metallic materials in general, and for magnesium and its alloys in particular, both for bare surfaces and coated. Scanning microelectrochemical techniques, such as local electrochemical impedance spectroscopy(LEIS), scanning electrochemical microscopy(SECM), scanning vibrating electrode technique(SVET), scanning ion-selective electrode technique(SIET) and scanning Kelvin probe(SKP) can provide information about the local electrochemical activity of metallic surfaces. In the present work, the applications of these techniques in corrosion studies of magnesium and its alloys are reviewed. Assessment of corrosion mechanisms, barrier properties of conventional coatings and active corrosion behavior of self-healing coatings are examined. Limitations and future developments in this area are discussed.展开更多
Bacillus thuringiensis （Bt） cotton is grown worldwide, including in saline soils, but the effect of salinity on ion fluxes of Bt cotton remains unknown. Responses of two transgenic Bt cotton genotypes （SGK321 and 2...Bacillus thuringiensis （Bt） cotton is grown worldwide, including in saline soils, but the effect of salinity on ion fluxes of Bt cotton remains unknown. Responses of two transgenic Bt cotton genotypes （SGK321 and 29317） and their corresponding receptors, Shiyuan 321 （SY321） and Jihe 321 （J321）, to 150 mmol L-1 NaCl stress were studied in a growth chamber. The root dry weight of SGK321 and 29317 under NaCl treatment was decreased by 30 and 31%, respectively. However, their corresponding receptor cultivars SY321 and J321 were less affected （19 and 24%, respectively）. The root length and surface area of the Bt cultivars were significantly decreased relative to their receptors under salt stress. NaCl treatment significantly increased CrylAc mRNA transcript levels in SGK321 and 29317 but did not affect Bt protein content in leaves or roots of either cultivar at 1 and 7 d after NaCl treatment. Fluxes of Na^＋, K^＋, and H^＋ in roots were investigated using the scanning ion-selective electrode technique. Both mean K^＋ efflux rate and transient K^＋ efflux of the Bt cultivars increased four-fold compared to their corresponding receptors when exposed to salinity stress. There were no significant differences in Na^＋ efflux between Bt and non-Bt cottons. Furthermore, the Na^＋ contents in roots and leaves of all genotypes dramatically increased under salt stress, whereas K^＋ contents decreased. Our results suggested that Bt cotton cultivars are more sensitive to salt stress than their receptor genotypes.展开更多
This work produced a Mg Al-layered double hydroxide by hydrothermal treatment of a plasma electrolytic oxidation(PEO)coating on magnesium alloy AZ31 in an phosphate electrolyte,followed by an ion-exchange reaction in ...This work produced a Mg Al-layered double hydroxide by hydrothermal treatment of a plasma electrolytic oxidation(PEO)coating on magnesium alloy AZ31 in an phosphate electrolyte,followed by an ion-exchange reaction in 0.1 M phosphate solution.The coated specimens were scratched.Characterization,including utilization of the localized technique SIET,measured the pH and p Mg distributions and optical morphologies around the artificial defects during immersion in 0.05 M NaCl solution.In contrast with phosphate loaded PEO/LDHs,a stronger alkalinization area(with pH 11.4~12.3)appeared in the passive PEO specimens.Due to formation of insoluble Mg(OH)_(2)products,the p Mg map showed depletion of Mg^(2+)in this high p H area.Combined with optical morphologies and SEM images,the better self-healing ability toward defects for phosphate loaded PEO/LDHs was confirmed.展开更多
Various Ionic and molecular activities in the extraceUular environment are vital to plant cell physiological processes. A noninvasive microsensing system （NMS） based on either the scanning ion-selective electrode te...Various Ionic and molecular activities in the extraceUular environment are vital to plant cell physiological processes. A noninvasive microsensing system （NMS） based on either the scanning ion-selective electrode technique （SIET） or the scanning polarographlc electrode technique （SPET） is able to obtain information regarding the transportation of various Ions/molecules in Intact samples under normal physiological conditions. The two-probe simultaneous test system （2STS） Is an Integrated system composed of SIET, SPET, and a Xu-Kunkel sampling protocol. In the present study, 2STS was able to simultaneously measure fluxes of H^＋ and O2 of the Uly （Lillum Iongiflorum Thunb. cv. Ace） pollen tube while avoiding interference between the two probes. The results Indicate that the proton fluxes were effluxes, whereas the oxygen fluxes were Influxes, and they were closely correlated to each other surrounding the constitutive alkaline band region. Specifically, when the proton effluxes increased, the oxygen Influxes also increased. Therefore, the hypothesis of condensed active mitochondria existing in the alkalized area of the pollen tube proposed by Hepler＇s group is supported.展开更多
SIET(Self-referencing Ion Electrode Technique)provides a novel electrophysiological tool which can non-invasively measure the dynamic influxes and effluxes of ions caused by the diffusion along the concentration gradi...SIET(Self-referencing Ion Electrode Technique)provides a novel electrophysiological tool which can non-invasively measure the dynamic influxes and effluxes of ions caused by the diffusion along the concentration gradients in vivo.However,in this technique ion fluxes are converted to voltage signals using an ion selective microelectrode at a small amplitude of lV,which is easy to be interfered by the ambient noise.Hence,effective solutions to the suppression of noise and calibration of ion flux measurement system are very important for this method.A K^+-selective microelectrode was constructed using liquid ion exchangers(LIX)to investigate ion transport over plant tissue.A standard concentration gradient which simulates plant living cells was produced by an electrode with a certain tip diameter,filled with a solution containing a known K+concentration in 100 mmol/L.An ion diffusion simulation model was established.This model evaluated the performance of ion flux measurement system in accuracy and reliability by comparing the consistency of the measured value and the predicted curve.K^+fluxes were measured within 25 min at each measuring point of distance 10,20,30,40,50,80,and 100 lm from the K+source,respectively.It can be seen that the K^+fluxes changes little,which indicates that ion flux measurement system has a reliable stability.The study provides a theoretical basis for a new non-invasive ion flux measurement method creation and a new sensors design.展开更多
文摘Exogenous proline is an effective agent for increasing plant tolerance to abiotic stress in plants. In this study, we evaluated its effect on seedlings of Siete Caldos chili pepper (Capsicum frutescens), a semi-domesticated variety. The Capsicum genus is known for its sensitivity to water stress. We pretreated the seedlings’ roots by immersing them in proline solutions (0, 2.5, 5, 7.5, and 10 mM) for 48 h. Then, we exposed them to water stress using a Hoagland nutrient solution supplemented with 10% polyethylene glycol (PEG-8000) for nine days. We analyzed key physiological and biochemical parameters, including relative water content, cell membrane stability index, electrolyte leakage, chlorophyll, and proline content. The results indicated that proline concentrations of 2.5 and 5 mM significantly increased tolerance to water stress, with 100% survival. These seedlings maintained greater hydration and cell membrane stability compared to non-pretreated seedlings. In contrast, at the highest concentrations (7.5 and 10 mM Pro), survival was 63.63% and 54.54%, respectively. This study demonstrated that exogenous proline enhances water stress tolerance in Capsicum frutescens seedlings by mitigating the negative impact on physiological and biochemical processes vital for survival. This theoretical foundation can be applied to improve chili seedling performance in controlled production environments.
基金supported by the National High-Tech R&D Program of China(863 Program,2013AA103004)the International S&T Cooperation Program of China(2014DFG32110)the National Key Research and Development Program of China(2014BAD08B020106)
文摘High nitrate(NO3-) in vegetables, especially in leaf vegetables poses threaten to human health. Selenium(Se) is an important element for maintaining human health, and exogenous Se application during vegetable and crop production is an effective way to prevent Se deficiency in human bodies. Exogenous Se shows positive function on plant growth and nutrition uptake under abiotic and/or biotic stresses. However, the influence of exogenous Se on NO3-accumulation in hydroponic vegetables is still not clear. In the present study, hydroponic lettuce plants were subjected to six different concentrations(0, 0.1, 0.5, 5, 10 and 50 μmol L–1) of Se as Na2 Se O3. The effects of Se on NO3-content, plant growth, and photosynthetic capacity of lettuce(Lactuca sativa L.) were investigated. The results showed that exogenous Se positively decreased NO3-content and this effect was concentration-dependent. The lowest NO3-content was obtained under 0.5 μmol L–1 Se treatment. The application of Se enhanced photosynthetic capacity by increasing the photosynthesis rate(Pn), stomatal conductance(Cs) and the transpiration efficiency(Tr) of lettuce. The transportation and assimilation of NO3-and activities of nitrogen metabolism enzymes in lettuce were also analysed. The NO3-efflux in the lettuce roots was markedly increased, but the efflux of NO3-from the root to the shoot was decreased after treated with exogenous Se. Moreover, Se application stimulated NO3-assimilation by enhancing nitrate reductase(NR), nitrite reductase(Ni R), glutamine synthetase(GS) and glutamate synthase enzyme(GOGAT) activities. These results provide direct evidence that exogenous Se shows positive function on decreasing NO3-accumulation via regulating the transport and enhancing activities of nitrogen metabolism enzyme in lettuce. We suggested that 0.5 μmol L–1 Se can be used to reduce NO3-content and increase hydroponic lettuce yield.
基金financially supported by the National Natural Science Foundation of China (Grant No. 51571201)
文摘The galvanic corrosion of the Q-phase/Al couple in 0.1 M NaCl solutions has been studied using the scanning vibrating electrode technique (SVET)f the scanning ion-selective electrode technique (SIET) and energy dispersive X-ray spectroscopy (EDX). The galvanic corrosion of the Q-phase/Al couple was found to be dependent on pH and immersion time. Current density maps obtained by SVET shows that the anodic oxidation processes emerge from Al in a localized manner in pH 2 and 6 solutions but is initiated in a uniform manner in pH 13 solution, whereas, the cathodic processes are more homogeneously distributed over the Q-phase at pH 2.6 and 13. It is seen that the Q-phase remains cathodic in the Q-phase/Al couple in acidic, neutral and alkaline solutions indicating that the galvanic polarity of the Q-phase is independent of pH. The effect of the galvanic corrosion was largest at pH 2 and 13 compared to pH 6. The pH map obtained by SIET indicates that the galvanic activity of the Q-phase/Al couple proceeds via heavy alkalization of the Q-phase surface with the generation of appreciable amounts of OH~ ions. The enrichment of Cu indicated by EDX is responsible for the observed cathodic activity of the Q-phase in the Q-phase/Al couple.
文摘The study of corrosion of magnesium and its alloys has emerged a hot topic in the applications of lightweight structural materials. The inherently high electrochemical activity of bare magnesium surfaces still lacks a convincing mechanism to describe the observed experimental characteristics, and it has prompted the development of various types of protective coatings with the aim of slowing metal dissolution. In recent years, new instruments and techniques have been developed to study with spatial resolution the local corrosion processes that occur in metallic materials in general, and for magnesium and its alloys in particular, both for bare surfaces and coated. Scanning microelectrochemical techniques, such as local electrochemical impedance spectroscopy(LEIS), scanning electrochemical microscopy(SECM), scanning vibrating electrode technique(SVET), scanning ion-selective electrode technique(SIET) and scanning Kelvin probe(SKP) can provide information about the local electrochemical activity of metallic surfaces. In the present work, the applications of these techniques in corrosion studies of magnesium and its alloys are reviewed. Assessment of corrosion mechanisms, barrier properties of conventional coatings and active corrosion behavior of self-healing coatings are examined. Limitations and future developments in this area are discussed.
基金supported by the National Natural Science Foundation of China (30871490)the Specialized Research Fund for the Doctoral Program of Higher Education of Chinathe Innovation Fund for Graduate Students of China Agricultural University (KYCX2011007)
文摘Bacillus thuringiensis （Bt） cotton is grown worldwide, including in saline soils, but the effect of salinity on ion fluxes of Bt cotton remains unknown. Responses of two transgenic Bt cotton genotypes （SGK321 and 29317） and their corresponding receptors, Shiyuan 321 （SY321） and Jihe 321 （J321）, to 150 mmol L-1 NaCl stress were studied in a growth chamber. The root dry weight of SGK321 and 29317 under NaCl treatment was decreased by 30 and 31%, respectively. However, their corresponding receptor cultivars SY321 and J321 were less affected （19 and 24%, respectively）. The root length and surface area of the Bt cultivars were significantly decreased relative to their receptors under salt stress. NaCl treatment significantly increased CrylAc mRNA transcript levels in SGK321 and 29317 but did not affect Bt protein content in leaves or roots of either cultivar at 1 and 7 d after NaCl treatment. Fluxes of Na^＋, K^＋, and H^＋ in roots were investigated using the scanning ion-selective electrode technique. Both mean K^＋ efflux rate and transient K^＋ efflux of the Bt cultivars increased four-fold compared to their corresponding receptors when exposed to salinity stress. There were no significant differences in Na^＋ efflux between Bt and non-Bt cottons. Furthermore, the Na^＋ contents in roots and leaves of all genotypes dramatically increased under salt stress, whereas K^＋ contents decreased. Our results suggested that Bt cotton cultivars are more sensitive to salt stress than their receptor genotypes.
基金the International Cooperation in Science and Technology Innovation between Governments,National Key Research and Development Program of China(No.2018YFE0116200)the National Natural Science Foundation of China(51971040)the Fundamental Research Funds for the Central Universities(2020CDJQY-A007)。
文摘This work produced a Mg Al-layered double hydroxide by hydrothermal treatment of a plasma electrolytic oxidation(PEO)coating on magnesium alloy AZ31 in an phosphate electrolyte,followed by an ion-exchange reaction in 0.1 M phosphate solution.The coated specimens were scratched.Characterization,including utilization of the localized technique SIET,measured the pH and p Mg distributions and optical morphologies around the artificial defects during immersion in 0.05 M NaCl solution.In contrast with phosphate loaded PEO/LDHs,a stronger alkalinization area(with pH 11.4~12.3)appeared in the passive PEO specimens.Due to formation of insoluble Mg(OH)_(2)products,the p Mg map showed depletion of Mg^(2+)in this high p H area.Combined with optical morphologies and SEM images,the better self-healing ability toward defects for phosphate loaded PEO/LDHs was confirmed.
基金Supported by the National Natural Science Foundation of China （30170552）, Beijing Natural Science Foundation （5042004）, Beijing Education Committee Science and Technology Development Project （KM200410028015） and Applicable Electronics Inc. （Forestdale, MA, USA）.
文摘Various Ionic and molecular activities in the extraceUular environment are vital to plant cell physiological processes. A noninvasive microsensing system （NMS） based on either the scanning ion-selective electrode technique （SIET） or the scanning polarographlc electrode technique （SPET） is able to obtain information regarding the transportation of various Ions/molecules in Intact samples under normal physiological conditions. The two-probe simultaneous test system （2STS） Is an Integrated system composed of SIET, SPET, and a Xu-Kunkel sampling protocol. In the present study, 2STS was able to simultaneously measure fluxes of H^＋ and O2 of the Uly （Lillum Iongiflorum Thunb. cv. Ace） pollen tube while avoiding interference between the two probes. The results Indicate that the proton fluxes were effluxes, whereas the oxygen fluxes were Influxes, and they were closely correlated to each other surrounding the constitutive alkaline band region. Specifically, when the proton effluxes increased, the oxygen Influxes also increased. Therefore, the hypothesis of condensed active mitochondria existing in the alkalized area of the pollen tube proposed by Hepler＇s group is supported.
基金This research was supported by the National Natural Science Foundation of China(61571443)the National Key Scientific Instrument and Equipment Development Projects(2011YQ080052)+2 种基金the Specialized Research Fund for the Doctoral Program of Higher Education(20130008110035)the Beijing Higher Education Young Elite Teacher Project(YETP1756)the Special Fund of Fundamental Research Funds for the Central Universities(2013YJ008).
文摘SIET(Self-referencing Ion Electrode Technique)provides a novel electrophysiological tool which can non-invasively measure the dynamic influxes and effluxes of ions caused by the diffusion along the concentration gradients in vivo.However,in this technique ion fluxes are converted to voltage signals using an ion selective microelectrode at a small amplitude of lV,which is easy to be interfered by the ambient noise.Hence,effective solutions to the suppression of noise and calibration of ion flux measurement system are very important for this method.A K^+-selective microelectrode was constructed using liquid ion exchangers(LIX)to investigate ion transport over plant tissue.A standard concentration gradient which simulates plant living cells was produced by an electrode with a certain tip diameter,filled with a solution containing a known K+concentration in 100 mmol/L.An ion diffusion simulation model was established.This model evaluated the performance of ion flux measurement system in accuracy and reliability by comparing the consistency of the measured value and the predicted curve.K^+fluxes were measured within 25 min at each measuring point of distance 10,20,30,40,50,80,and 100 lm from the K+source,respectively.It can be seen that the K^+fluxes changes little,which indicates that ion flux measurement system has a reliable stability.The study provides a theoretical basis for a new non-invasive ion flux measurement method creation and a new sensors design.
