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 （ETR11） and in PSI （ETR1） by 79.4 and 66.3%, respectively, increased non-light induced non-photochemical quenching in PSII （q^No） 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 ETR, and ETR1 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
In this study, we investigated the effects of exogenous calcium nitrate on photoinhibition and thylakoid protein level in peanut plants under heat （40 ℃） and high irradiance （HI） （1,200 mmol/m2 per s） stress. C...In this study, we investigated the effects of exogenous calcium nitrate on photoinhibition and thylakoid protein level in peanut plants under heat （40 ℃） and high irradiance （HI） （1,200 mmol/m2 per s） stress. Compared with control seedlings （cultivated in 0 mmol/L Ca（NO3）2 medium）, the maximal photochemical efficiency of photosystem II （PSII） in Ca2t‐treated plants showed a slight decrease after 5 h stress, accompanied by lower degree of PSII closure （1‐qP）, higher non‐photochemical quenching, and lower level of membrane damage. Ca2t inhibitors were used to analyze the varieties of antioxidant enzymes activity and PSII proteins. These results indicated that Ca2t could protect the subunits of PSII reaction centers from photoinhibition by reducing the generation of reactive oxygen species. In the presence of both ethyleneglycol‐bis（2‐aminoethylether）‐tetraacetic acid and ascorbic acid （AsA）, the net degradation of the damaged D1 protein was faster than that only treated with AsA. Our previous study showed that either the transcriptional or the translational level of calmodulin was obviously higher in Ca2t‐treated plants. These results suggested that, under＆amp;nbsp;heat and HI stress, the Ca2t signal transduction pathway can al eviate the photoinhibition through regulating the protein repair process besides an enhanced capacity for scavenging reactive oxygen species.展开更多
So far, many important questions and problems concerning the structure and mechanism of photosynthetic oxygen evolution are still unsolved. On the basis of recent achievements in this field, a new structure model is p...So far, many important questions and problems concerning the structure and mechanism of photosynthetic oxygen evolution are still unsolved. On the basis of recent achievements in this field, a new structure model is proposed whereby two H2O molecules bind asymmetrically to two manganese ions (Mn1Ⅱ and Mn4Ⅲ) at the open end of 'C' shaped cluster and keep rather large distance. Two histidine residues coordinate to the other two manganese ions in higher oxi-展开更多
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 （ETR11） and in PSI （ETR1） by 79.4 and 66.3%, respectively, increased non-light induced non-photochemical quenching in PSII （q^No） 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 ETR, and ETR1 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.
基金supported by the Natural Science Foundation of Shandong Province (ZR2009DZ007 and ZR2011CQ042)the Supporting Plan of National Science and Technology of China (2014BAD11B04)+1 种基金the earmarked fund for Modern Agro-industry Technology Research System (CARS-14)Shandong Major Projects of Independent Innovation Achievement Transformation (2012ZHZXIA0418)
文摘In this study, we investigated the effects of exogenous calcium nitrate on photoinhibition and thylakoid protein level in peanut plants under heat （40 ℃） and high irradiance （HI） （1,200 mmol/m2 per s） stress. Compared with control seedlings （cultivated in 0 mmol/L Ca（NO3）2 medium）, the maximal photochemical efficiency of photosystem II （PSII） in Ca2t‐treated plants showed a slight decrease after 5 h stress, accompanied by lower degree of PSII closure （1‐qP）, higher non‐photochemical quenching, and lower level of membrane damage. Ca2t inhibitors were used to analyze the varieties of antioxidant enzymes activity and PSII proteins. These results indicated that Ca2t could protect the subunits of PSII reaction centers from photoinhibition by reducing the generation of reactive oxygen species. In the presence of both ethyleneglycol‐bis（2‐aminoethylether）‐tetraacetic acid and ascorbic acid （AsA）, the net degradation of the damaged D1 protein was faster than that only treated with AsA. Our previous study showed that either the transcriptional or the translational level of calmodulin was obviously higher in Ca2t‐treated plants. These results suggested that, under＆amp;nbsp;heat and HI stress, the Ca2t signal transduction pathway can al eviate the photoinhibition through regulating the protein repair process besides an enhanced capacity for scavenging reactive oxygen species.
文摘So far, many important questions and problems concerning the structure and mechanism of photosynthetic oxygen evolution are still unsolved. On the basis of recent achievements in this field, a new structure model is proposed whereby two H2O molecules bind asymmetrically to two manganese ions (Mn1Ⅱ and Mn4Ⅲ) at the open end of 'C' shaped cluster and keep rather large distance. Two histidine residues coordinate to the other two manganese ions in higher oxi-
