During low tide,the intertidal seagrass Enhalus acoroides is often exposed to high light and desiccation,which can seriously threaten its survival,at least partly by inhibiting photosystem Ⅱ(PSⅡ)activity.The respons...During low tide,the intertidal seagrass Enhalus acoroides is often exposed to high light and desiccation,which can seriously threaten its survival,at least partly by inhibiting photosystem Ⅱ(PSⅡ)activity.The response of leaves of E.acoroides to high light and desiccation was compared for seedlings and mature plants.Results show that the resistance of seedling and mature leaves to high light was quite similar,but to desiccation was very different.Seedling leaves were more sensitive to desiccation than the mature plant leaves,but had better water retention.The damage of desiccation to seedling leaves was mainly caused by dehydration,whereas that to mature plant leaves was caused by hypersaline toxicity.The recovery rate of PSⅡ of seedling leaves was significantly slower than that of the mature plants after the stresses disappeared,which may at least partly contribute to seedling mortality in the wild.In addition,compared to high light,desiccation seriously inhibited the recovery rate of PSⅡ activities even if the leaves became fully rehydrated to their normal relative water content(RWC)in the following re-immersion.Desiccation inhibited the recovery rate of RC/CS_(M)(reaction center per cross section(at t=t_(Fm)))to decrease the production of assimilatory power,which maybe the cause of the slower PSⅡ recovery in desiccation treatments.This study demonstrates that desiccation particularly coupling with high light have a very negative ef fect on the PSⅡ of E.acoroides during low tide and the sensitivity of seedlings and mature plants to desiccation is significantly different,which have important reference significance to choose an appropriate transplanting depth where seedlings and mature plants of E.acoroides not only receive sufficient light for growth,but also that minimize desiccation stress during low tide.展开更多
Samara is the reproductive organ (seed) for many tree species in arid land in northwestern China. It is ecologically important in population development due to its dispersal function. However, information on its photo...Samara is the reproductive organ (seed) for many tree species in arid land in northwestern China. It is ecologically important in population development due to its dispersal function. However, information on its photosynthesis and effect of environmental stresses on its photosynthesis is still very limited. In the present study, responses of photosystem II (PSII) activity in samara and leaf of Siberian maple to short-term chilling/freezing and subsequent recovery potential were comparatively investigated by using polyphasic fluorescence test. The samara had more efficient photosynthesis (Fv/Fm and PIABS) and more efficient electron transport (φEo) but lower energy dissipation (DIo/RC) than leaf. Generally, the PSII performance and the electron transport for both samara and leaf were inhibited under low temperature stress, accompanied by an increase of energy dissipation in PSII reaction centers (RCs). PSII of both samara and leaf was not markedly affected by chilling and could acclimate to chilling stress. Short-term freezing could completely inhibit PSII activity in both samara and leaf, indicated by the drop of values of Fv/Fm, PIABS, φEo to zero. PSII functional parameters of short-term dark frozen samara could be largely recovered whereas those of frozen leaf could not be recovered. The higher tolerance of samara to short-term low temperature stress than leaf is of great ecological significance for seed development, population establishment of Siberian maple.展开更多
Due to 4f electron characteristics and alternation valence, cerium involved in an oxidation-reduction reaction in plant, closely relating to photosynthesis. Our studies proved that cerium could promote photosynthesis ...Due to 4f electron characteristics and alternation valence, cerium involved in an oxidation-reduction reaction in plant, closely relating to photosynthesis. Our studies proved that cerium could promote photosynthesis and greatly improve spinach growth. However, the mechanism of promoting energy transfer and conversion by cerium remains unclear. Here we reported that the effects of Ce3+ on energy transfer and oxygen evolution in photosystem Ⅱ(PSⅡ) isolated from spinach, which was related to 4f electron characteristics and alternation valence in Ce molecule. The methods of absorption spectrum, fluorescence spectrum were used in the research. Results showed that Ce3+ treatment at low concentration could suitably change PSⅡ microenvironment, increase the absorbance of visible light, improve the energy transfer among amino acids within PSⅡ protein-pigment complex, and accelerate energy transport from tyrosine residue to chlorophyll a. In summary, the photochemical activity of PSⅡ(fluorescence quantum yield) and its oxygen evolving rate were enhanced by Ce3+.展开更多
Blue and red lights differently regulate leaf photosynthesis. Previous studies indicated that plants under blue light generally exhibit better photosynthetic characteristics than those under red light. However, the re...Blue and red lights differently regulate leaf photosynthesis. Previous studies indicated that plants under blue light generally exhibit better photosynthetic characteristics than those under red light. However, the regulation mechanism of related photosynthesis characteristics remains largely unclear. Here, four light qualities treatments(300 μmol m–2 s–1) including white fluorescent light(FL), blue monochromatic light(B, 440 nm), red monochromatic light(R, 660 nm), and a combination of red and blue light(RB, R:B=8:1) were carried out to investigate their effects on the activity of photosystem II(PSII) and photosystem I(PSI), and photosynthetic electron transport capacity in the leaves of cucumber(Cucumis sativus L.) seedlings. The results showed that compared to the FL treatment, the R treatment significantly limited electron transport rate in PSII(ETRII) and in PSI(ETRI) by 79.4 and 66.3%, respectively, increased non-light induced non-photochemical quenching in PSII(ΦNO) and limitation of donor side in PSI(ΦND) and reduced most JIP-test parameters, suggesting that the R treatment induced suboptimal activity of photosystems and inhibited electron transport from PSII donor side up to PSI. However, these suppressions were effectively alleviated by blue light addition(RB). Compared with the R treatment, the RB treatment significantly increased ETRII and ETRI by 176.9 and 127.0%, respectively, promoted photosystems activity and enhanced linear electron transport by elevating electron transport from QA to PSI. The B treatment plants exhibited normal photosystems activity and photosynthetic electron transport capacity similar to that of the FL treatment. It was concluded that blue light is more essential than red light for normal photosynthesis by mediating photosystems activity and photosynthetic electron transport capacity.展开更多
The excitation energy transfer from phycobiliproteins to thylakoid PSII of higher plants was investigated. When incubated with spinach thylakoids, phycobiliproteins isolated from red and blue- green algae transferred ...The excitation energy transfer from phycobiliproteins to thylakoid PSII of higher plants was investigated. When incubated with spinach thylakoids, phycobiliproteins isolated from red and blue- green algae transferred light energy absorbed to spinach PSII. The efficiency of energy transfer was dependent on the kind of phycobiliproteins used. If spinach thylakoids were replaced by the thylakoids of Brassica chinensis, R phycoerythin or C- phycocyanin did not transfer their excitation energy to PSII of Brassica chinensis unless allophycocyanin was present.展开更多
To investigate the effect of reduced salinity on diatoms’ capacity to cope with changing ultraviolet radiation(U VR) and photosynthetically active radiation(PAR),Skeletonema costatum was grown in a range of salinity(...To investigate the effect of reduced salinity on diatoms’ capacity to cope with changing ultraviolet radiation(U VR) and photosynthetically active radiation(PAR),Skeletonema costatum was grown in a range of salinity(15,25,and 35).The photo system Ⅱ(PSⅡ) function was analyzed by increasing PAR and UVR to mimic a mixing event in turbulent waters.The re sults show that high UVR exposure significantly reduced PSII activity,especially in cells grown at low salinity.UVR,but not salinity,stimulated the ’removal’ rate of PSII protein PsbA.Salinity alone,in the range of 15 to 35,did not regulate PSⅡ acceptor region;however,the low salinity+UVR treatment decreased the energy flux for electron transport per PSⅡ reaction center in S.costatum.It showed that low salinity exacerbated the damaging effect of UVR on PSⅡ function in S.costatum by suppressing Psb A protein synthe sis and modifying the photochemistry of PSⅡ.Although higher catalase(CAT) activity and NPQs were induced,they were unable to prevent the combined damage effect of low salinity+UVR.Our findings indicate that reduced salinity and increased UVR potentially affect the abundance and distribution of S.costatum with the escalation of climate disturbances.展开更多
[Objective] The paper was to investigate effects of glyphosate stress on physiological characteristics and protein expression of photosystem Ⅱ(PSⅡ) in genentically modified soybean GTS 40-3-2 seedlings under severe ...[Objective] The paper was to investigate effects of glyphosate stress on physiological characteristics and protein expression of photosystem Ⅱ(PSⅡ) in genentically modified soybean GTS 40-3-2 seedlings under severe drought condition. [Method] A pot experiment was carried out in growth chamber to determine the response of genetically modified soybean treated by severe drought stress and different concentrations of glyphosate at the third compound leaf stage. [Result] Severe drought treatment increased the electrolyte leakage(EL), superoxide dismutase(SOD) and peroxidase(POD) activities, and decreased the relative water content(RWC), chlorophyll content, and catalase(CAT) activity. The EL, SOD and POD activities were significantly increased in severe drought and glyphosate treatments, which were related to glyphosate concentrations. The chlorophyll content decreased, which was also related to glyphosate concentrations. But the BWC and CAT activity were not affected by glyphosate concentrations. Western blot displayed that PSⅡ protein Lhcb2 was not affected by stress conditions and stably expressed. D1, D2 and Lhcb4 protein level decreased, and there was no significant change in Lhcb1 expression under severe drought stress. The protein levels of D1, D2, Lhcb1 and Lhcb4 decreased with the increase of glyphosate concentrations under severe drought and glyphosate stress. When the glyphosate concentrations were 0.92 and 1.84 kg·ai/hm^2, the protein levels of D1, D2 and Lhcb4 were slightly higher than those in severe drought stress. When the glyphosate concentrations were 3.68 and 7.36 kg·ai/hm^2, the protein level of D1, D2, Lhcb1 and Lhcb4 decreased sharply. [Conclusion] This research provides a theoretical basis for production of genetically modified soybean.展开更多
A comparative study on chloroplast ultrastructure and light harvesting complex of photosystem Ⅱ (LHC Ⅱ) was conducted between a new rice mutant (W2555) and its wild type (WT). The chloroplasts of W2555 had less thyl...A comparative study on chloroplast ultrastructure and light harvesting complex of photosystem Ⅱ (LHC Ⅱ) was conducted between a new rice mutant (W2555) and its wild type (WT). The chloroplasts of W2555 had less thylakoids and grana stacks compared with the wild type. There was no significant change in the composition of LHC Ⅱ polypeptide in W2555, while a decline had been noted in LHC Ⅱ content. Northern blot analysis with a specific cab gene probe showed no appreciable difference in the LHC Ⅱ mRNA level between the W2555 and its wild type. The precursors of chlorophyll synthesis, δ-aminolevulinic acid (ALA) and porphobilinogen (PBG) were over accumulated in W2555, but the other precursors were all decreased. These results indicated that the decreased level of LHC Ⅱ in the mutant W2555 was attributed to the change of cab gene transcription, but a blockage in chlorophyll biosynthesis due to the formation of uroporphyrinogen Ⅲ (Urogen Ⅲ).展开更多
基金Supported by the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDB42000000)the National Natural Science Foundation of China(No.32071577)+2 种基金the International Partnership Program of Chinese Academy of Sciences(No.GJHZ2039)the Shandong Provincial Natural Science Foundation(No.ZR201911130493)the Taishan Industrial Experts Program(No.Tscy20200102)。
文摘During low tide,the intertidal seagrass Enhalus acoroides is often exposed to high light and desiccation,which can seriously threaten its survival,at least partly by inhibiting photosystem Ⅱ(PSⅡ)activity.The response of leaves of E.acoroides to high light and desiccation was compared for seedlings and mature plants.Results show that the resistance of seedling and mature leaves to high light was quite similar,but to desiccation was very different.Seedling leaves were more sensitive to desiccation than the mature plant leaves,but had better water retention.The damage of desiccation to seedling leaves was mainly caused by dehydration,whereas that to mature plant leaves was caused by hypersaline toxicity.The recovery rate of PSⅡ of seedling leaves was significantly slower than that of the mature plants after the stresses disappeared,which may at least partly contribute to seedling mortality in the wild.In addition,compared to high light,desiccation seriously inhibited the recovery rate of PSⅡ activities even if the leaves became fully rehydrated to their normal relative water content(RWC)in the following re-immersion.Desiccation inhibited the recovery rate of RC/CS_(M)(reaction center per cross section(at t=t_(Fm)))to decrease the production of assimilatory power,which maybe the cause of the slower PSⅡ recovery in desiccation treatments.This study demonstrates that desiccation particularly coupling with high light have a very negative ef fect on the PSⅡ of E.acoroides during low tide and the sensitivity of seedlings and mature plants to desiccation is significantly different,which have important reference significance to choose an appropriate transplanting depth where seedlings and mature plants of E.acoroides not only receive sufficient light for growth,but also that minimize desiccation stress during low tide.
基金supported by Knowledge Innovation Program of Chinese Academy of Sciences (KZCX2-YW-335)Program of 100 Distinguished Young Scientists of the Chinese Academy of SciencesNational Natural Science Foundation of China (40673070, 40872169)
文摘Samara is the reproductive organ (seed) for many tree species in arid land in northwestern China. It is ecologically important in population development due to its dispersal function. However, information on its photosynthesis and effect of environmental stresses on its photosynthesis is still very limited. In the present study, responses of photosystem II (PSII) activity in samara and leaf of Siberian maple to short-term chilling/freezing and subsequent recovery potential were comparatively investigated by using polyphasic fluorescence test. The samara had more efficient photosynthesis (Fv/Fm and PIABS) and more efficient electron transport (φEo) but lower energy dissipation (DIo/RC) than leaf. Generally, the PSII performance and the electron transport for both samara and leaf were inhibited under low temperature stress, accompanied by an increase of energy dissipation in PSII reaction centers (RCs). PSII of both samara and leaf was not markedly affected by chilling and could acclimate to chilling stress. Short-term freezing could completely inhibit PSII activity in both samara and leaf, indicated by the drop of values of Fv/Fm, PIABS, φEo to zero. PSII functional parameters of short-term dark frozen samara could be largely recovered whereas those of frozen leaf could not be recovered. The higher tolerance of samara to short-term low temperature stress than leaf is of great ecological significance for seed development, population establishment of Siberian maple.
基金Project supported by the National Natural Science Foundation of China (20671067, 30470150)
文摘Due to 4f electron characteristics and alternation valence, cerium involved in an oxidation-reduction reaction in plant, closely relating to photosynthesis. Our studies proved that cerium could promote photosynthesis and greatly improve spinach growth. However, the mechanism of promoting energy transfer and conversion by cerium remains unclear. Here we reported that the effects of Ce3+ on energy transfer and oxygen evolution in photosystem Ⅱ(PSⅡ) isolated from spinach, which was related to 4f electron characteristics and alternation valence in Ce molecule. The methods of absorption spectrum, fluorescence spectrum were used in the research. Results showed that Ce3+ treatment at low concentration could suitably change PSⅡ microenvironment, increase the absorbance of visible light, improve the energy transfer among amino acids within PSⅡ protein-pigment complex, and accelerate energy transport from tyrosine residue to chlorophyll a. In summary, the photochemical activity of PSⅡ(fluorescence quantum yield) and its oxygen evolving rate were enhanced by Ce3+.
基金supported by the Special Fund for Nonprofit Industry (Agriculture) Research Project (201303014)Earmarked Fund for Beijing Fruit Vegetable Innovation Team Project of Modern Agro-industry Technology Research System (GCTDZJ2014033007) in China
文摘Blue and red lights differently regulate leaf photosynthesis. Previous studies indicated that plants under blue light generally exhibit better photosynthetic characteristics than those under red light. However, the regulation mechanism of related photosynthesis characteristics remains largely unclear. Here, four light qualities treatments(300 μmol m–2 s–1) including white fluorescent light(FL), blue monochromatic light(B, 440 nm), red monochromatic light(R, 660 nm), and a combination of red and blue light(RB, R:B=8:1) were carried out to investigate their effects on the activity of photosystem II(PSII) and photosystem I(PSI), and photosynthetic electron transport capacity in the leaves of cucumber(Cucumis sativus L.) seedlings. The results showed that compared to the FL treatment, the R treatment significantly limited electron transport rate in PSII(ETRII) and in PSI(ETRI) by 79.4 and 66.3%, respectively, increased non-light induced non-photochemical quenching in PSII(ΦNO) and limitation of donor side in PSI(ΦND) and reduced most JIP-test parameters, suggesting that the R treatment induced suboptimal activity of photosystems and inhibited electron transport from PSII donor side up to PSI. However, these suppressions were effectively alleviated by blue light addition(RB). Compared with the R treatment, the RB treatment significantly increased ETRII and ETRI by 176.9 and 127.0%, respectively, promoted photosystems activity and enhanced linear electron transport by elevating electron transport from QA to PSI. The B treatment plants exhibited normal photosystems activity and photosynthetic electron transport capacity similar to that of the FL treatment. It was concluded that blue light is more essential than red light for normal photosynthesis by mediating photosystems activity and photosynthetic electron transport capacity.
文摘The excitation energy transfer from phycobiliproteins to thylakoid PSII of higher plants was investigated. When incubated with spinach thylakoids, phycobiliproteins isolated from red and blue- green algae transferred light energy absorbed to spinach PSII. The efficiency of energy transfer was dependent on the kind of phycobiliproteins used. If spinach thylakoids were replaced by the thylakoids of Brassica chinensis, R phycoerythin or C- phycocyanin did not transfer their excitation energy to PSII of Brassica chinensis unless allophycocyanin was present.
基金Supported by the Shandong Provincial Natural Science Foundation(Nos.ZR2019MC015,ZR2020QC025,ZR2020MD092)the open project of Rongcheng Marine Industrial Technology Research Institute,Ludong University(No.KF20180001)the Key Technology Research and Development Program of Shandong(No.2019GSF107091)。
文摘To investigate the effect of reduced salinity on diatoms’ capacity to cope with changing ultraviolet radiation(U VR) and photosynthetically active radiation(PAR),Skeletonema costatum was grown in a range of salinity(15,25,and 35).The photo system Ⅱ(PSⅡ) function was analyzed by increasing PAR and UVR to mimic a mixing event in turbulent waters.The re sults show that high UVR exposure significantly reduced PSII activity,especially in cells grown at low salinity.UVR,but not salinity,stimulated the ’removal’ rate of PSII protein PsbA.Salinity alone,in the range of 15 to 35,did not regulate PSⅡ acceptor region;however,the low salinity+UVR treatment decreased the energy flux for electron transport per PSⅡ reaction center in S.costatum.It showed that low salinity exacerbated the damaging effect of UVR on PSⅡ function in S.costatum by suppressing Psb A protein synthe sis and modifying the photochemistry of PSⅡ.Although higher catalase(CAT) activity and NPQs were induced,they were unable to prevent the combined damage effect of low salinity+UVR.Our findings indicate that reduced salinity and increased UVR potentially affect the abundance and distribution of S.costatum with the escalation of climate disturbances.
基金Supported by Youth Fund of Genetic Engineering of Provincial Finance(2018QNJJ-023)Applied Basic Research of Sichuan Science and Technology Program(2018JY0153)Excellent Thesis Fund Project of Genetic Engineering of Provincial Finance(2016 LWJJ-010)
文摘[Objective] The paper was to investigate effects of glyphosate stress on physiological characteristics and protein expression of photosystem Ⅱ(PSⅡ) in genentically modified soybean GTS 40-3-2 seedlings under severe drought condition. [Method] A pot experiment was carried out in growth chamber to determine the response of genetically modified soybean treated by severe drought stress and different concentrations of glyphosate at the third compound leaf stage. [Result] Severe drought treatment increased the electrolyte leakage(EL), superoxide dismutase(SOD) and peroxidase(POD) activities, and decreased the relative water content(RWC), chlorophyll content, and catalase(CAT) activity. The EL, SOD and POD activities were significantly increased in severe drought and glyphosate treatments, which were related to glyphosate concentrations. The chlorophyll content decreased, which was also related to glyphosate concentrations. But the BWC and CAT activity were not affected by glyphosate concentrations. Western blot displayed that PSⅡ protein Lhcb2 was not affected by stress conditions and stably expressed. D1, D2 and Lhcb4 protein level decreased, and there was no significant change in Lhcb1 expression under severe drought stress. The protein levels of D1, D2, Lhcb1 and Lhcb4 decreased with the increase of glyphosate concentrations under severe drought and glyphosate stress. When the glyphosate concentrations were 0.92 and 1.84 kg·ai/hm^2, the protein levels of D1, D2 and Lhcb4 were slightly higher than those in severe drought stress. When the glyphosate concentrations were 3.68 and 7.36 kg·ai/hm^2, the protein level of D1, D2, Lhcb1 and Lhcb4 decreased sharply. [Conclusion] This research provides a theoretical basis for production of genetically modified soybean.
文摘A comparative study on chloroplast ultrastructure and light harvesting complex of photosystem Ⅱ (LHC Ⅱ) was conducted between a new rice mutant (W2555) and its wild type (WT). The chloroplasts of W2555 had less thylakoids and grana stacks compared with the wild type. There was no significant change in the composition of LHC Ⅱ polypeptide in W2555, while a decline had been noted in LHC Ⅱ content. Northern blot analysis with a specific cab gene probe showed no appreciable difference in the LHC Ⅱ mRNA level between the W2555 and its wild type. The precursors of chlorophyll synthesis, δ-aminolevulinic acid (ALA) and porphobilinogen (PBG) were over accumulated in W2555, but the other precursors were all decreased. These results indicated that the decreased level of LHC Ⅱ in the mutant W2555 was attributed to the change of cab gene transcription, but a blockage in chlorophyll biosynthesis due to the formation of uroporphyrinogen Ⅲ (Urogen Ⅲ).
