Journal of Korean Society for Atmospheric Environment
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v.22
no.E2
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pp.89-98
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2006
Two tobacco cultivars (Nicotiana tabacum L.), Bel-B and Bel-W3, tolerant and sensitive to ozone, respectively, were grown in a greenhouse supplied with charcoal filtered air and exposed to 200 ppb ozone for 4 hr. Effects on chlorophyll fluorescence, net photosynthesis, and stomatal conductance are described. Quantum yield was calculated from chlorophyll fluorescence and the initial slope of the assimilation-light curve measured by the gas exchange method. Only the sensitive cultivar, Bel-W3, developed visual injury symptoms on up to 50% of the $5^{th}$ leaf. The maximum net photosynthetic rate of ozone-treated plants was reduced 40% compared to control plants immediately after ozone fumigation in the tolerant cultivar; however, photosynthesis recovered by 24 hr post fumigation and remained at the same level as control plants. On the other hand, ozone exposure reduced maximum net photosynthesis up to 50%, with no recovery, in the sensitive cultivar apparently causing permanent damage to the photosystem. Reductions in apparent quantum efficiency, calculated from the assimilation-light curve, differed between cultivars. Bel-B showed an immediate depression of 14% compared to controls, whereas, Bel-W3 showed a 27% decline. Electron transport rate (ETR), at saturating light intensity, decreased 58% and 80% immediately after ozone treatment in Bel-B and Bel-W3, respectively. Quantum yield decreased 28% and 36% in Bel-B and Bel-W3, respectively. It can be concluded that ozone caused a greater relative decrease in linear electron transport than maximum net photosynthesis, suggesting greater damage to PSII than the carbon reduction cycle.
Photosynthetic responses to dehydration were examined by the simulataneous measurement of O2 evolution and chlorophyll (Chl) fluorescence in green pepper leaves. Dehydration was induced by immersing the plant roots directly in the Hoagland solution containing varying concentration (2-30%) of polyethylene glycol(PEG-6000) . Water potential of the leaf was decreased time-and concentation -dependently by PEG-treatment. The decrease in water potential of leaf was correlated with the decrease in both the maximal photosynthesis (Pmax) and quantum yield of O2 evolution, but Pmax dropped more rapidly than quantum yield at all water deficit conditions tested. However, Chl fluorescence parameters were not affected much. Dehydration did not change the initial fluorescence (Fo) and maximum photochemical efficiency(Fv/Fm) of photosystem(PS) II. Both the photochemical quenching (qP) and non-photochemical quenching(NPQ) were not changed by dehydration under low PFR(50 $\mu$mols m-2s-1 ). In contrast, under high PFR(270$\mu$mols m-2s-1)qP was slightly decreased while NPQ was greatly increased. The fast induction kinetics of Chl fluroecence showed no change in Chl fluorescence pattern by dehydration at high PFR (640 $\mu$mols m-2s-1 ), but exhibited a significant drop in peak level(Fp)at low PRFR (70$\mu$mols m-2s-1 ). PS I oxidation and reduction kinetics revealed normal reduction but delayed oxidation to P-700+, suggesting no lesionin electron flow from PSII to PSI , but impaired electron transport to NADP+,These results suggest that water stress caused by PEG-treatment results in the reduction of photosynthesis, promarily due to the reducted electron trasport from PSI to NADP+ or hampered subsequent steps involving Calvin Cycle.
Kim, Hyun-Ju;Kang, In-Soon;Lee, Chin-Bum;Lee, Choon-Hwan;Cho, Sung-Ho;Moon, Byoung-Yong
Journal of Photoscience
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v.12
no.1
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pp.33-39
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2005
Plants possess the ability to dissipate the excitation energy for the protection of photosynthetic apparatus from absorbed excess light. Heat dissipation is regulated by xanthophyll cycle in thylakoid membranes of chloroplasts. We investigated the mechanistic aspects of xanthophyll cycle-dependent photoprotection against low-temperature photoinhibition in plants. Using barley and rice as chilling-resistant species and sensitive ones, respectively, chilling-induced chlorophyll fluorescence quenching, composition of xanthophyll cycle pigments and mRNA expression of the zeaxanthin epoxidase were examined. Chilled barley plants exhibited little changes in chlorophyll fluorescence quenching either of photochemical or non-photochemical nature and in the photosynthetic electron transport, indicating low reduction state of PS II primary electron acceptor. In contrast to the barley, chilled rice showed a marked decline in those parameters mentioned above, indicating the increased reduction state of PS II primary electron acceptor. In addition, barley plants were shown to have a higher capacity to elevate the pool size of xanthophyll cycle pigments in response to cold stress compared to rice plants. Such species-dependent regulation of xanthophyll cycle activity was correlated with the gene expression level of cold-induced zeaxanthin epoxidase. Chilled rice plants depressed the gene expression of zeaxanthin epoxidase, whereas barley increased its expression in response to cold stress. We suggest that chilling-induced alterations in the pool size of xanthophyll cycle pigments related to its capacity would play an important role in regulating plant's sensitivity to chilling stress.
The aim of this study is to determine the drought stress index through photochemical analysis in red pepper (Capsiumannuum L.). The photochemical interpretation was performed in the basis of the relation between Kautsky effect and Photosystem II (PSII) following the measurement of chlorophyll, pheophytin contents, and $CO_2$ assimilation in drought stressed 5-week-old red pepper plants. The $CO_2$ assimilation rate was severely lowered with almost 77% reduction of chlorophyll and pheophytin contents at four days after non-irrigation. It was clearly observed that the chlorophyll fluorescence intensity rose from a minimum level (the O level), in less than one second, to a maximum level (the P-level) via two intermediate steps labeled J and I (OJIP process). Drought factor index (DFI) was also calculated using measured OJIP parameters. The DFI was -0.22, meaning not only the initial inhibition of PSII but also sequential inhibition of PSI. In real, most of all photochemical parameters such as quantum yield of the electron transport flux from Quinone A ($Q_A$) to Quinone B ($Q_B$), quantum yield of the electron transport flux until the PSI electron acceptors, quantum yield of the electron transport flux until the PSI electron acceptors, average absorbed photon flux per PSII reaction center, and electron transport flux until PSI acceptors per cross section were profoundly reduced except number of QA reducing reaction centers (RCs) per PSII antenna chlorophyll (RC/ABS). It was illuminated that at least 6 parameters related with quantum yield/efficiency and specific energy fluxes (per active PSII RC) could be applied to be used as the drought stress index. Furthermore, in the combination of parameters, driving forces (DF) for photochemical activity could be deduced from the performance index (PI) for energy conservation from photons absorbed by PSII antenna until the reduction of PSI acceptors. In conclusion, photochemical responses and their related parameters can be used as physiological DFI.
Highly stable $O_2$-evolving cells and thylakoid membranes have been obtained from the cyanobacterium, Synechococcus PCC7002, by immobilization with polyvinylalcohol(PVA). The absorption peak showed the blue-shift of about 3 nm after immobilization of intact cells and thylakoid membranes as well as isolation of thylakoid membranes. Photosynthetic electron transport activities, especially PS II activity showed greater stability in the PVA-immobilized cells and thylakoid membranes when stored at $4^{\circ}C$ than in those at $25^{\circ}C$. When the cells were threated at higher temperature, the level of Fo and Fv increased. After imobilization, however, Fo showed no change. This suggests that the immobilization can protect against the damages of PS II complex, especially a water-spiliting system, by heat treatment.
Park, So-Hyun;Yoo, Sung-Yung;Lee, Min-Ju;Park, Jong-Yong;Song, Ki-Tae;Kim, Tae Wan;Lee, Byung-Moo
KOREAN JOURNAL OF CROP SCIENCE
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v.60
no.1
/
pp.1-7
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2015
The photochemical characteristics were analyzed in the context of sowing time and different levels of fertilized nitrogen during the maize (Zea mays L.) growth. When maize was early sawn, the fluorescence parameters related with electron-transport, in photosystem II (PSII) and PSI, were effectively enhanced with the higher level of fertilized nitrogen. Highest values were observed in maize leaves grown in double N-fertilized plot. The photochemical parameters were declined in the progress of growth stage. In early growth stage, the fluorescence parameters were highest, and then reduced to about half of the parameters related with electron transport on PSII and PSI at middle and late growth stages. In 1/2 N plot, the photochemical energy dissipation was measured to 13% in term of active reaction center per absorbed photon resulting in decrease in performance index and driving force of electron. This decrease induced to lower the photochemical effectiveness. In 2 N plots, the electron transport flux from $Q_A$ to $Q_B$ per cross section and the number of active PSII RCs per cross section were considerably enhanced. It was clearly indicated that the connectivity between photosynthetic PSII and PSI, i.e. electron transport, was far effective.
Garbary, David J.;Miller, Anthony G.;Scrosati, Ricardo A.
ALGAE
/
v.29
no.4
/
pp.321-331
/
2014
Vertebrata lanosa is an abundant and obligate red algal epiphyte of Ascophyllum nodosum that forms part of a complex and highly integrated symbiotic system that includes the ascomycete, Mycophycias ascophylli. As part of ongoing studies to resolve interactions among species in the symbiosis, we used pulse amplitude modulation fluorimetry of chlorophyll a fluorescence, from photosystem II (PSII), to measure the maximum quantum yield ($F_v/F_m$) of PSII [$QY(II)_{max}$] and relative photosynthetic electron transport rates (rETR), as a function of light intensity, in order to evaluate the photosynthetic capacity of the two algal symbionts in the field and in the laboratory under different treatments. Our primary question was 'Is the ecological integration of these species reflected in a corresponding physiological integration involving photosynthetic process?' In the laboratory we measured changes in $QY(II)_{max}$ in thalli of V. lanosa and A. nodosum over one week periods when maintained together in either attached or detached treatments or when maintained separated from each other. While the $QY(II)_{max}$ of PSII of A. nodosum remained high and showed no significant variation among treatments, V. lanosa showed decreasing performance in the following conditions: V. lanosa attached to A. nodosum, V. lanosa in the same culture, but not attached to A. nodosum, and V. lanosa alone. These results are consistent with observations in which rETR was reduced in V. lanosa maintained alone versus attached to A. nodosum. Values for $QY(II)_{max}$ in V. lanosa measured in the field in fully submerged thalli were similar to those measured in the laboratory when V. lanosa was attached to it obligate host A. nodosum. Our results provide evidence of a physiological association of the epiphyte and its host that reflects the known ecology.
Tomato yellow leaf curl China virus is a species of the widespread geminiviruses. The infection of Nicotiana benthamiana by Tomato yellow leaf curl China virus (TYLCCNV) causes a reduction in photosynthetic activity, which is part of the viral symptoms. ${\beta}C1$ is a viral factor encoded by the betasatellite DNA ($DNA{\beta}$) accompanying TYLCCNV. It is a major viral pathogenicity factor of TYLCCNV. To elucidate the effect of ${\beta}C1$ on plants' photosynthesis, we measured the relative chlorophyll (Chl) content and Chl fluorescence in TY-LCCNV-infected and ${\beta}C1$ transgenic N. benthamiana plants. The results showed that Chl content is reduced in TYLCCNV A-infected, TYLCCNV A plus $DNA{\beta}$ (TYLCCNV A + ${\beta}$)-infected and ${\beta}C1$ transgenic plants. Further, changes in Chl fluorescence parameters, such as electron transport rate, $F_v/F_m$, NPQ, and qP, revealed that photosynthetic efficiency is compromised in the aforementioned N. benthamiana plants. The presense of ${\beta}C1$ aggravated the decrease of Chl content and photosynthetic efficiency during viral infection. Additionally, the real-time quantitative PCR analysis of oxygen evolving complex genes in photosystem II, such as PsbO, PsbP, PsbQ, and PsbR, showed a significant reduction of the relative expression of these genes at the late stage of TYLCCNV A + ${\beta}$ infection and at the vegetative stage of ${\beta}C1$ transgenic N. benthamiana plants. In summary, this study revealed the pathogenicity of TYLCCNV in photosynthesis and disclosed the effect of ${\beta}C1$ in exacerbating the damage in photosynthesis efficiency by TYLCCNV infection.
High soil salinity is the most severe threat to global rice production as it causes a significant decline in rice yield. Here, we investigated the effects of various plant extracts on rice plant stress associated with high salinity. Additionally, we examined various physiological and biochemical parameters such as growth, photosynthetic activity, chlorophyll content, and lipid peroxidation - in rice plants after treatment with selected plant extracts under salt stress conditions. Of the 11 extracts tested, four - soybean leaf, soybean stem, moringa (Moringa oleifera), and Undaria pinnatifida extracts - were found to effectively reduce salt stress. A reduction of only 3-23% in shoot fresh weight was observed in rice plants under salt stress that were treated with these extracts, compared to the 43% reduction observed in plants that were exposed to stress but not given plant extract treatments (control plants). The effectiveness varied with the concentration of the plant extracts. Water content was higher in rice plants treated with the extracts than in the control plants after 6 d of salt stress, but not after 4 d of salt stress. Although photosynthetic efficiency (Fv/Fm), electron transport rate (ETR), and the content of pigments (chlorophyll and carotenoid) varied based on the types and levels of stress and the extracts that the rice plants were treated with, generally, photosynthetic efficiency and pigment content were higher in the treated rice compared to control plants. Reactive oxygen species (ROS), such as superoxide radicals, hydrogen peroxide (H2O2), and malondialdehyde (MDA), increased as the duration of stress increased. ROS and MDA levels were lower in the treated rice than in the control plants. Proline and soluble sugar accumulation also increased with the duration of the stress period. However, proline and soluble sugar accumulation were lower in the treated rice than in the control plants. Generally, the values of all the parameters investigated in this study were similar, regardless of the plant extract used to treat the rice plants. Thus, the extracts found to be effective can be used to alleviate the adverse effects of stress on rice crops associated with high-salinity soils.
Lee, Solji;Oh, Chang-Young;Han, Sim-Hee;Kim, Ki Woo;Kim, Pan-Gi
Korean Journal of Agricultural and Forest Meteorology
/
v.16
no.1
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pp.22-28
/
2014
This study was conducted to investigate the photosynthetic characters of Populus alba${\times}$glandulosa cuttings in response to elevated $CO_2$ concentration and air temperature for selecting tree species adaptive to climate change. The cuttings were grown in environment controlled growth chambers with two combinations of $CO_2$ concentration and air temperature conditions: (i) $22^{\circ}C$ + $CO_2$ 380 ${\mu}mol$$mol^{-1}$ (control) and (ii) $27^{\circ}C$ + $CO_2$ 770 ${\mu}mol$$mol^{-1}$ (elevated) for almost three months. The cuttings under the elevated treatment showed reduced tree height and photosynthetic pigment contents such as chlorophyll and carotenoid. In particular, the elevated treatment resulted in a marked reduction in the chlorophyll a closely associated with $CO_2$ fixative reaction system. Different levels of reduction in photosynthetic characters were found under the elevated treatment. A decrease was noted in photochemical reaction system parameters: net apparent quantum yield (7%) and photosynthetic electron transport rate (14%). Moreover, a significant reduction was obvious in $CO_2$ fixative reaction system parameters: carboxylation efficiency (52%) and ribulose-1,5-bisphosphate(RuBP) regeneration rate (24%). These results suggest that the low level of photosynthetic capacity may be attributed to the decreased $CO_2$ fixative reaction system rather than photochemical reaction system.
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