• Journal of Environmental Science International
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• v.5 no.4
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• pp.545-553
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• 1996

The effects of 0.2 ppm ozone on the developing chloroplast of barley (Hordeum vulgare L.) seedling during greening were examined by chlorophyll contents, photosynthetic electron tiansport activity, Fo, Fv and fluorescence quenching coefficient. Chlorophyll contents of seedling treated with ozone were not changed in comparison with the control during the 96 h greening experiment, but PS II activity of the chloroplasts of seedlings treated with ozone was decreases by- l5%. Fo was slightly decreased but Fv was decreases by 5% in comparison with the control, In fluorescence quenching analysis, qP and qE were decreased by 11% and 9%, respectively, in comparison with the control. These results suggest that oxidation site of PS II is the site affected mostly and PQ pool is also affected slightly by 0.2 ppm ozone.

• Journal of Environmental Science International
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• v.24 no.12
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• pp.1591-1600
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• 2015

The response of the freshwater microalga, Chlorella vulgaris, to heavy metal stress was examined based on chlorophyll fluorescence analysis to assess the toxic effects of heavy metals in freshwater ecosystems. When toxic effects were analyzed using regular chlorophyll fluorescence analysis, photosystem II activity($F_v/F_m$) decreased significantly when exposed to $Cu^{2+}$ and $Hg^{2+}$ for 12 h, and decreased in the order of $Hg^{2+}>Cu^{2+}>Cd^{2+}>Ni^{2+}$ when exposed for 24h. The effective photochemical quantum yield(${\phi}{\prime}_{PSII}$), chlorophyll fluorescence decrease ratio($R_{Fd}$), minimal fluorescence yield($F_o$), and non-photochemical quenching(NPQ), but not photochemical quenching(qP), responded sensitively to $Hg^{2+}$, $Cu^{2+}$, and $Cd^{2+}$. These results suggest that $F_v/F_m$, as well as ${\phi}{\prime}_{PSII}$, $R_{Fd}$, $F_o$, and NPQ could be used to assess the effects of heavy metal ions in freshwater ecosystems. However, because many types of heavy metal ions and toxic compounds co-occur under natural conditions, it is difficult to assess heavy metal toxicity in freshwater ecosystems. When Chlorella was exposed to heavy metal ions for 12 or 24h, $F_v/F_m$ and maximal fluorescence yield($F_m$) changed in response to $Hg^{2+}$ and $Cu^{2+}$ based on image analysis. However, assessing quantitatively the toxic effects of several heavy metal ions is challenging.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.5
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• pp.676-682
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• 2012

The objectives of this study focused on measuring chlorophyll fluorescence related to drought stress comparing some parameters. Almost parameters were declined although they were not significant on the basis of mean values of fluorescence of total leaf area. While the ratio of fluorescence intensity variable chlorophyll ($F_V$) to fluorescence intensity maximal chlorophyll ($F_M$) was not changed, the effective quantum yield of photochemical energy conversion in photosystemII (${\Phi}PSII$) and chlorophyll fluorescence decrease ratio ($R_{fd}$) were slightly reduced, indicating inhibition of the electron transport from quinone bind protein A ($Q_A$) to quinone bind protein B ($Q_B$). Some parameters such as non-photochemical quenching rate ($NPQ_{_-LSS}$) and coefficients of non-photochemical quenching of variable fluorescence (qN) in mid-zone of leaf and near petiole zone leaf were significantly enhanced within 4 days after drought stress, which can be used as physiological stress parameters. Decrease in ${\Phi}PSII$ could was significantly measured in all leaf zones. In conclusion, three parametric evidences for chlorophyll fluorescence responses such as ${\Phi}PSII$, NPQ, and qN insinuated the possibility of photophysiological indices under drought stress.

• Journal of Plant Biology
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• v.34 no.4
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• pp.303-309
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• 1991

Limitation of photosynthesis in detached Chinese cabbage (Brassica campestris L.) leaves was induced by feeding of mannose (25 mM) for 12 h in the light, and changes in the basic thylakoid functions under this condition were investigated. The acid soluble phosphate contend and CO2 uptake rate was decreased by 66% and 67%, respectively. However, the starch content was increased by 24% compared to those of controls. From the fast induction curves of chlorophyll fluorescence, dark level fluorescence (Fo) slightly increased while intermediate plateau fluorescence level (FI) to peak level fluorescence (Fp) transient was significantly decreased with a slight decrease in the Fo-to-FI transient. This data means that reduction of secondary electron acceptor of PSII (QB) might be more severely inhibited than that of primary electron acceptor of PSII (QA) by decrease in phosphate level. The strong decline of (Fv)m//Fm ratio suggests that efficiency of excitation energy capture by PSII was decreased markedly. The quenching of Fo (qO), an indicator of state transition, was also occurred over the slow induction kinetics of chlorophyll fluorescence. From quenching analysis, fluorescence was dominantly quenched by nonphotochemical quenchings (qE+qT). These results showed that the capture and transfer efficiency of excitation energy to PSII reaction center in thylakoid was decreased with the decline of leaf phosphate level, and that the state transition was occurred during the induction of photosynthesis under these conditions.

• Journal of Environmental Science International
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• v.1 no.1
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• pp.13-21
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• 1992

The inhibitory effects of mercury ions on the growth of barley seedlings were studied and the distribution of metal elements in the organs of treated plants was investigated by using synchrotron radiation induced X-ray emission (SRIXE). Although the treatment of mercury ions caused growth inhibition, the mercury-specific increase in variable fluorescence and the abolishment of energy-dependent quenching in broken barley chloroplasts as shown by Moon et at. (1992) were not observed in the leaves of growth-inhibited seedlings. Instead the treatment of mercury decreased Fmax and Fo values. However, Fmax/Fo ratio and photochemical and nonphotochemical quenching coefficients were not affected significantly. By SRIXE analysis of $10\mu\textrm{m}$ mercury chloride treated seedlings, accumulation of mercury in roots was observed after 1 hour of treatment and similar concentration was sustained for 48 hours. Relative contents of mercury was high in roots and underground nodes where seeds were attachedl but was very low in leaves. Iron and zinc were also distributed mainly in the lower parts of the seedlings. However after 72 hours of treatment the contents of these metals in roots decreased and their distribution became more uniform, which may lead to death of the plants. These results suggest that the observed inhibitory effects on barley seedlings upto 48 hours after the treatment is not due to direct damages in the photosynthetic apparatus, but due to its accumulation in roots and the consequent retardation of the growth of barley seedlings. The decrease in Fmax and Fo is probably due to the decrease in chlorophyll and protein contents caused by the retardation of growth. The observed slow expansion of primary leaves could be also explained by the retardation of growth, but the fluorescence induction pattern from the leaves did not show characteristic symptoms of leaves under water stress.

• The Plant Pathology Journal
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• v.32 no.4
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• pp.300-310
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• 2016

Pathogen infection in plants induces complex responses ranging from gene expression to metabolic processes in infected plants. In spite of many studies on biotic stress-related changes in host plants, little is known about the metabolic and phenotypic responses of the host plants to Pseudomonas cichorii infection based on image-based analysis. To investigate alterations in tomato plants according to disease severity, we inoculated plants with different cell densities of P. cichorii using dipping and syringe infiltration methods. High-dose inocula (${\geq}10^6cfu/ml$) induced evident necrotic lesions within one day that corresponded to bacterial growth in the infected tissues. Among the chlorophyll fluorescence parameters analyzed, changes in quantum yield of PSII (${\Phi}PSII$) and non-photochemical quenching (NPQ) preceded the appearance of visible symptoms, but maximum quantum efficiency of PSII ($F_v/F_m$) was altered well after symptom development. Visible/near infrared and chlorophyll fluorescence hyperspectral images detected changes before symptom appearance at low-density inoculation. The results of this study indicate that the P. cichorii infection severity can be detected by chlorophyll fluorescence assay and hyperspectral images prior to the onset of visible symptoms, indicating the feasibility of early detection of diseases. However, to detect disease development by hyperspectral imaging, more detailed protocols and analyses are necessary. Taken together, change in chlorophyll fluorescence is a good parameter for early detection of P. cichorii infection in tomato plants. In addition, image-based visualization of infection severity before visual damage appearance will contribute to effective management of plant diseases.

• Journal of Plant Biology
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• v.37 no.1
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• pp.37-42
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• 1994

Correlative changes between photosynthetic O2 exchange rates and room temperature Chl fluorescence were investigated in wheat (Triticum aestivum L.) chloroplasts treated with high temperature for 5 min. With increasing treatment temperature, photosynthetic O2 evolution rate mediated by PSII was decreased, showing 50% inhibition at 38$^{\circ}C$ (I50). But PSI activity measured by O2 uptake rates was stimulated as a function of increasing temperature. Dark level fluorescence (Fo)-temperature (T) analysis showed that fluorescence rising temperature (Tr), critical temperature (Tc), and peak temperature (Tp) was 38, 43, and 52$^{\circ}C$, respectively. Quenching analysis of Chl fluorescence showed that both the oxidized fraction of plastoquinone (qQ) and degree of thylakoid membrane energization (qNP) increased up to 4$0^{\circ}C$ and then declined dramatically. These results suggest that Tr is correlated with temperature showing a 50% of inhibition of photosynthesis and under mild high temperature stress, qNP is worth regarding as indicator for heat-induced damage of photosynthesis.

• ALGAE
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• v.20 no.2
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• pp.121-125
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• 2005

The modern integrated fish-seaweed mariculture has been tested to reduce the environmental impacts of an intensive fed culture. To obtain the best seaweed bioremediation performance, the effects of therapeutants used for fish disease control on the selected seaweed species should be considered. As a selected seaweed, Porphyra yezoensis was tested with six commercial antibiotics including erythromycin thiocyanate_A, erythromycin thiocyanate_B, oxytetracycline, doxycycline, pefloxacin, and amoxicillin trihydrate under the batch incubation at a photon flux density of 10 $\mu$mol ${\cdot}m^{-2}\;{\cdot}\;s^{-1}$ at 15$^{\circ}C$. Among the tested commercial antibiotics, erythromycin thiocyanate_A, erythromycin thiocyanate_B, oxytetracycline, and doxycycline showed decreases in Fv/Fm, the photochemical efficiency of photosystem II, with a dose-dependant and time-dependant manner. From the quenching analysis of chlorophyll fluorescence, three differential patterns were observed in the antibiotics-treated Porphyra: (1) high nonphotochemical quenching (NPQ) and low photochemical quenching (qP) in the cases of Erythromycin thiocyanate_B and amoxicillin trihydrate, (2) high NPQ and high qP in the case of pefloxacin and (3) low NPQ and low qP in the case of oxytetracycline. These results indicated that antibiotics affected in various ways on the photosynthetic apparatus, reflecting differential lesion sites of antibiotics. In addition, the rates of ammonium uptake also decreased with a decrease of Fv/Fm in P. yezoensis thalli treated with erythromycin thiocyanate_B and oxytetracycline. Therefore, the four antibiotics mentioned could affect the bioremediation capacity of the selected seaweed species in the integrated fish-seaweed mariculture system due to the decrease of photosynthetic activity and the simultaneous decrease of ammonium uptake.

• Journal of Plant Biotechnology
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• v.37 no.4
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• pp.567-573
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• 2010

To ascertain the effect of over-expressed maize calreticulin in tomato plant on tobamovirus movement in addition to validating potentiality of the gene (ZmCRT) as a means for the virus-resistance resource, four ZmCRT-expressing homozygous lines were generated from the T0 plants as using an Agrobacterium-mediated transformation, nucleic acid analyses, and a conventional breeding method. Of them, a line was subjected to the bioassay for tolerances to tobacco mosaic virus-U1 (TMV-U1) and tomato mosaic virus (ToMV) followed by RT-PCR and a chlorophyll fluorescence quenching analyses. Both transgenic plants transcribing ZmCRT and wild-type plants showed no symptom by 20 days after viruses inoculation, however the photosystem II quantum yield parameter measured from the upper leaves of ToMV-inoculated plants revealed that ZmCRT transgenic plants have higher photosynthetic ability than wild-type ones at that time, which indirectly implies that over-expressed ZmCRT product acts as a barrier to the cell-to-cell and/or systemic movement of ToMV. Moreover, ZmCRT transgenic plants showed remarkably longer shoot length than wild-type ones in 40 days after TMV-U1 or ToMV inoculation each, which might be resulted from higher photosynthetic ability during the phase not yet showing any external symptoms. Collectively, over-expressed ZmCRT protein in tomato plants is able to interrupt the systemic movement of infected TMV-U1 and ToMV even though not perfect.

• Journal of Plant Biology
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• v.38 no.1
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• pp.11-18
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• 1995

Mercury-induced changes in Chl a fluorescence induction kinetics of scratched barley leaf segments were dependent on the presence of light. By the treatment of 50$\mu$M HgCl2 under light condition, Fm and Fp were decreased. However, they were not significantly reduced under dark condition even after 2 h of mercury treatment. Under dark condition the decrease in variable fluorescence (Fv) after P transient was blocked within 20 min of the treatment. The analysis of fast fluorescence rise curve suggests that the inhibitory site of mercury under both light and dark conditions is not at QB binding site and the inhibition does not involve the increase in inactive PSII centers. Under light condition the decrease in Fp was partially recovered by addition of 50 $\mu$M NH2OH. These results suggest that a major inhibitory site of mercury under dark condition is at the reducing side of PSII and the site under light condition is at the oxidizing side of PSII possibly in addition to the one under dark condition. Under both light and dark conditions, energy-dependent quenching(qE) was alomost completely repressed within 20 min of mercury treatment and noticible change in Fo was not observed. The qE repression is probably due to the blockage of transthylakoid ΔpH formation.