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Photosynthesis

About: Photosynthesis is a research topic. Over the lifetime, 19789 publications have been published within this topic receiving 895197 citations.


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Journal ArticleDOI
TL;DR: The results indicate that under N limitation both the light-collecting system and the photosynthetic rate decrease, however, the increased dissipation of excess energy shows that there is excess light absorbed at midday.
Abstract: The involvement of the xanthophyll cycle in photoprotection of N-deficient spinach (Spinacia oleracea L. cv Nobel) was investigated. Spinach plants were fertilized with 14 mM nitrate (control, high N) versus 0.5 mM (low N) fertilizer, and grown under both high- and low-light conditions. Plants were characterized from measurements of photosynthetic oxygen exchange and chlorophyll fluorescence, as well as carotenoid and cholorophyll analysis. Compared with the high-N plants, the low-N plants showed a lower capacity for photosynthesis and a lower chlorophyll content, as well as a lower rate of photosystem II photosynthetic electron transport and a corresponding increase in thermal energy dissipation activity measured as nonphotochemical fluorescence quenching. The low-N plants displayed a greater fraction of the total xanthophyll cycle pool as zeaxanthin and antheraxanthin at midday, and an increase in the ratio of xanthophyll cycle pigments to total chlorophyll. These results indicate that under N limitation both the light-collecting system and the photosynthetic rate decrease. However, the increased dissipation of excess energy shows that there is excess light absorbed at midday. We conclude that spinach responds to N limitation by a combination of decreased light collection and increased thermal dissipation involving the xanthophyll cycle.

252 citations

Journal ArticleDOI
TL;DR: Arabidopsis thaliana plants were grown at 23 degrees C end changes in carbohydrate metabolism, photosynthesis and photosynthetic gene expression were studied after the plants were shifted to 5degrees C end.
Abstract: Arabidopsis thaliana plants were grown at 23 degrees C end changes in carbohydrate metabolism, photosynthesis and photosynthetic gene expression were studied after the plants were shifted to 5 degr ...

252 citations

Journal ArticleDOI
TL;DR: The evidence strongly suggests that HCO(3) (-) was a direct C source for photosynthesis and serves to raise the CO(2) concentration around the carboxylase to levels high enough for effective fixation.
Abstract: The possibility of HCO 3 − transport in the blue-green alga (cyanobacterium) Coccochloris peniocystis has been investigated. Coccochloris photosynthesized most rapidly in the pH range 8 to 10, where most of the inorganic C exists as HCO 3 − . If photosynthesis used only CO 2 from the external solution the rate of photosynthesis would be limited by the rate of HCO 3 − dehydration to CO 2 . Observed rates of photosynthesis at alkaline pH were as much as 48-fold higher than could be supported by spontaneous dehydration of HCO 3 − in the external solution. Assays for extracellular carbonic anhydrase were negative. The evidence strongly suggests that HCO 3 − was a direct C source for photosynthesis. Weakly buffered solutions became alkaline during photosynthesis with a one-to-one stoichiometry between OH − appearance in the medium and HCO 3 − initially added. Alkalization occurred only during photosynthesis and was blocked by 3-(3,4-dichlorophenyl)-1, 1-dimethylurea, diuron. It is suggested that HCO 3 − was transported into cells of Coccochloris in exchange for OH − produced as a result of HCO 3 − fixation in photosynthesis. The inorganic C concentration required to support a rate of photosynthesis of half the maximum rate ( K m ) was 6 micromolar at pH 8.0 or, in terms of available CO 2 , a K m of 0.16 micromolar. This value is two orders of magnitude lower than reported K m values for the d-ribulose-1,5-bisphosphate carboxylase for blue-green algae. It is suggested that the putative HCO 3 − transport by Coccochloris serves to raise the CO 2 concentration around the carboxylase to levels high enough for effective fixation.

251 citations

Journal ArticleDOI
TL;DR: Applying the method to flint and dent breeding population led to a substantial increase in the photosynthetic capacity of hybrids between selected F 3 inbreeding families grown at suboptimal temperature, demonstrating that the method is an efficient selection tool for improving the cold tolerance of maize through breeding.
Abstract: The possibility of using quenching analysis of chlorophyll a fluorescence as a selection tool for improving the cold tolerance of maize was investigated in six genotypes differing greatly in the ability to develop a competent photosynthetic apparatus at low temperature. Upon gradual cooling, measurements of the quantum yield of electron transport (Φ PSII ) indicated that leaves of tolerant genotypes, that developed at suboptimal temperature (15°C), maintained higher rates of electron transport than leaves of sensitive genotypes. This difference was largely due to the ability of the tolerant plants to keep higher efficiency of excitation energy capture by open photosystem II reaction centres (F' v /F' m ). The absence of genotypic differences in leaves that developed at optimal temperature indicates that the trait is not expressed constitutively, but relies on adaptation mechanisms. Furthermore, the genotypic difference was not expressed under increasing illumination at 15°C and 25°C suggesting that the trait is also low-temperature-specific and is not expressed solely in response to increasing excess light energy. Applying the method to flint and dent breeding population led to a substantial increase (up to 31%) in the photosynthetic capacity of hybrids between selected F 3 inbreeding families grown at suboptimal temperature, demonstrating that the method is an efficient selection tool for improving the cold tolerance of maize through breeding.

251 citations

Journal ArticleDOI
TL;DR: Partial purification of the pigment complex responsible for light induced absorption changes at 700 mμ in photosynthesis was obtained in this article, where chlorophyll was removed from chloroplasts of water and hexane soluble materials, leaving an active particulate preparation.

251 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20242
20232,453
20225,090
2021738
2020732
2019616