• Journal of Plant Biology
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• v.25 no.1
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• pp.21-36
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• 1982

The activity of photosystem II in isolated chloroplast form the leaves of Sedum sarmentosum was measured. The photoreduction rate of DCPIP by photosystem II showed the circadian rhythm with a peak at near midday sample for a continuing fine day and at near afternoon between nidday and sunset sample for a continuing cloudy day in summer. The optimum light intensity of photoreduction by photosystem II in the chloroplast preparation was about 5~9$\times$$10^4$ lux. The saturated light intensity was over 9$\times$$10^1$lux. Photosystem II activity was inhibited by even the lowest concentration of lead. When Pi and ATP of the same concentration as Pb were added to the reaction mixture containing Tris buffer lacking of Pi prior to Pb incubation, photosystem II activity was protected from Pb-inhibiting effect by the pretreament of Pi and ATP. It was assumed that Pb inhibiiton was probably due to one, P-depriving by the precipitates of $Pb_3$ $($Pb_4$)_2$ in the reaction mixture and the other, partially Pb-combing with Pi groups of the active site of photosystem II.

• Journal of Photoscience
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• v.9 no.2
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• pp.59-62
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• 2002

In chilling-sensitive plants, the donor side of Photosystem II is inhibited by the chilling treatment in the dark, while the acceptor side of Photosystem I is inhibited by the chilling under the moderate light. Since the addition of inhibitors of electron transfer from Photosystem II protects Photosystem I from chilling induced photoinhibition of Photosystem I, inhibition or down-regulation of Photosystem II activity in vivo may also protect Photosystem I from photoinhibition. It was revealed that dark-chilling pretreatment actually protected Photosystem I from photoinhibition. The results imply that down-regulation of Photosystem II under stress conditions may have a role to protect Photosystem I from photoinhibition.

• Journal of Photoscience
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• v.5 no.1
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• pp.1-10
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• 1998

The susceptibility of chilling-resistant spinach plants. and of chilling-sensitive squash plants to photoinhibition was compared in terms of the activity of photosystem II, in relation to the deuce of fatty acid unsaturation of chloroplast membrane lipids. From thylakoid membranes of the plants. monogalactosyl diacylgtycerol, digalactosyl diacylglycerol. sulfoquinovosyt diacylglycerol, and phosphatidylglycerol were seperated as major lipid classes. It was found that the content of cis-unsaturated fatty acids of phosphatidylglycerol was greater by 32% in spinach than that in squash. When leaf disks were exposed to light at 5$\circ$C, 15$\circ$C and 25$\circ$C, photochemical efficiency of photosystem II. measured as the ratio of the variable to the maximum fluorescence of chlorophyll, declined markedly in squash plants, as compared to spinach plants. When leaf disks were exposed to strong light in the presence of lincomycin, an inhibitor of protein synthesis in chloroplasts, photoinhibition was accelerated in the two types of plants. Moreover, lincomycin treatment abolished the differences in the degree of susceptibility to strong light, which had been observed between the two types of plants. When the extent of photoinhibition of photosystem II-mediated electron transport was compared in thylakoid membranes isolated from the two types of plants, there were no differences in the degree of inactivation of photosystem II activity. However, when intact leaf disks were exposed to strong light either at 10$\circ$C or at 25$\circ$C, and then were allowed to recover either at 17$\circ$C or at 25$\circ$C in dim light. chilling-resistant plants such as spinach and pea showed marked recovery from photoinhibition, in contrast to chilling-sensitive plants, such as squash and sweet potato. whose recovery was strongly dependent on the temperature. These findings are discussed in relation to the unsaturation of fatty acids in membrane phosphatidylglycerol. It appears that fatty acid unsaturation of membrane lipids accelerates the recovery of photosystem H from photoinhibition, without affecting the photo-induced inactivation process of photosystem II associated with photoinhibition.

• Journal of Practical Agriculture & Fisheries Research
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• v.22 no.1
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• pp.35-42
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• 2020

This study was conducted to investigate the photosystem II activities of Cercis chinensis by soil water condition. Drought stress was induced by withholding water and waterlogging treatments was immerging the pots for 15 days. Results showed that the relative activities per reaction center such as ABS/RC, TRo/RC and Dio/RC were significantly increased compared with the control group after 12 days in waterlogging treatments. Particularly, Dio/RC increased substantially under waterlogging stress, indicating that excessive energy was consumed by heat dissipation. Furthermore, the performance index on absorption basis(PI_abs) and responses to structural and functional PS II(SFI_abs) were dramatically decreased after 15 days in both the drought and waterlogging treatments, which reflects the relative reduction state of the photosystem II. These results of chlorophyll a fluorescence by OKJIP analysis show that the sensitive changes photosystem II activity. Thus, on the basis of our results that Cercis chinensis was exhibited a strong reduction of photosynthetic activity to waterlogging stress, and OKJIP parameters such as ABS/RC, DIo/RC, PI_abs and SFI_abs could be useful indicator to monitor the physiological states of Cercis chinensis under soil water condition.

• Journal of Photoscience
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• v.7 no.2
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• pp.39-44
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• 2000

To examine the chilling tolerance lipids, we compared the chilling susceptibility of photosystem II of wild type tobacco plants with that of transgenic tobacco plants, in which the sensitivity to chilling had been enhanced by genetic modification of fatty acid unsaturation of chloroplast membrane lipids. The transgenic tobacco plants were found to contain reduced levels of unsaturated membrane fatty acids by being tansformed with cDNA for glycerol-3-phosphate acyltransferase from squash. For the purpose of studying on the functional integrity of photosystem II during low-temperature photoinhibition, the photochemical efficiency was measured as the ration of the maximun fluorescence of chlorophyll (Fv/Fm) of photosystem II. In parallel with an investigation on the transgenic plants, susceptibility of chilling-resistant species, such as spinah and pea, and of chilling-sensitive ones, such as squash and sweet potato, to low-temperature photoinhibition was also compared in terms of room temperature-induced chlorophyll fluorescence from photosystem II. When leaf disks from the two genotypes of tobacco plants were exposed to light at 5$^{\circ}C$, the transgenic plants showed more rapid decline in photochemical activity of photosysytme II than wild-type plants. When they were pretreated with lincomycin, an inhibitor of chloroplast-encoded protein synthesis, the extent of photoinhibition was even more accelerated. More impottantly, they showed a comparable extent of photoinhibition in the presence of lincomycin, making a clear contrast to the discrepancy observed in the discrepancy observed in the absence of lincomycin. Restoration of Fv/Fm during recovery from low-temperature photoinhibition occurred more slowly in the transgenic tobacco plants than the wild-type. These findings are discussed in relation to fatty acid unsaturation of membrane phosphatidylglycerol. It appears that the ability of plants to rapidly regenerate the active photosystem II complex from might explain, in part, why chilling-resistant plants can toleratlow-temperature photoinhibition.

• Journal of Plant Biology
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• v.33 no.4
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• pp.277-283
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• 1990

Inactivation and reactivation of photosynthetic oxygen evolving complex were studied with isolated spinach (Spinacia oleraceda. L.) photosystem II particles by the activity of oxygen evolution and chlorophyll fluorescence. When the particles were treated with Tris and urea, the oxygen evolution was inactivated and three polypeptides having molecular weights of 33 kDa, 24 kDa and 18 kDa were simultaneously released. But in NaCl-treated particles, two polypeptides of 24 kDa and 18 kDa were removed from PS II particles. The oxygen evolution activities of Tris and urea-treated particles were not restored by adding cation ions (Mg2+, Mn2+ and Ca2+), but the NaCl-treated particles were restored by exogenously added Ca2+. The removal of these extrinsic polypeptides, especially 33 kDa, markedly showed the decrease of the variable fluorescence (Fv). These results are likely to be due to dissipate thermal energy by antenna of photosystem II complexes.

• Journal of Photoscience
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• v.3 no.1
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• pp.23-28
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• 1996

To investigate the structure and function of photosystem I, cartridge mutagenesis technique was used to inactivate the psaB gene of photosystem I. From the screen, many strains which have potential defects in photosystem I were generated. Biochemical analysis revealed that B2, one of the mutant, had a reduced amount of chlorophyll. Electron transfer activitx from photosystem II to photosystem I as oxygen uptake was the rate of 64 % of wild type. Also B2 showed a decreased photosystem I activity when measured by 77 K fluorescence emission spectrum. Particularly, immunodetection analysis showed that the B2 had reduced amount of PsaA/PsaB, but a normal range of PsaC and PsaD. Here we present a photoheterotrophic mutant for psaB gene as a unique model strain for future study of structural/functional relationship and biogenesis of photosystem I.

• Journal of Environmental Science International
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• v.31 no.4
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• pp.311-318
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• 2022

In this study, we analyzed the relationships between weather factors and photosystem II activity (F_v/F_m), as a measure of photochemical efficiency, in three cool-season turfgrasses commonly planted on golf courses in Jeju, South Korea: perennial ryegrass (Lolium perenne L.), Kentucky bluegrass (Poa pratensis L.), and creeping bentgrass (Agrostis palustris Huds.). In all three turfgrasses, F_v/F_m was higher during late summer than during early summer. However, in late summer, F_v/F_m was significantly lower in perennial ryegrass than in the other two species. In early summer, F_v/F_m in perennial ryegrass and Kentucky bluegrass was positively correlated with mean low temperature and extreme minimum temperature, whereas, in late summer, this parameter in Kentucky bluegrass and creeping bentgrass was positively correlated with relative humidity, and in creeping bentgrass was negatively correlated with mean high temperature, mean low temperature, and extreme maximum temperature. These results indicate that raising low temperatures is favorable for perennial ryegrass and Kentucky bluegrass in early summer, whereas, in late summer, the lowering of high temperatures proves to be beneficial for creeping bentgrass, and raising relative humidity is conducive to the growth of Kentucky bluegrass and creeping bentgrass. These findings will contribute to improving the selection and management of turfgrasses on golf courses and sports fields.

• Journal of Plant Biology
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• v.19 no.4
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• pp.95-99
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• 1976

This work deals with different extraction media and reaction mixtures on photosystem II activity of Spinach chloroplasts. The photoreduction rate of ferricyanide and DPIP by intact chloroplasts which extracted with four kinds of extraction media; S-Tris-N pH 7.2, 8.0, S-Tricine-N pH 7.2, 8.0, was measured in five kinds of reaction mixtures; S-Tris-N pH 7.2, 8.0, S-Tricine-N pH 7.2, 8.0, 0.05 M-Tris pH 7.2. The extraction medium which shows the highest photoreduction rate was S-Tris-N at pH 7.2 and S-Tricine-N at pH 8.0. As to the reaciton mixture, S-Tricine-N pH 8.0 showed the highest rate. On the complex effects of extraction media and reaction mixtures, the highest photordeuction rate of Hill oxidant by intact chloroplasts was obtained by S-Tris-N pH 7.2 extraction medium and S-Tricine-N pH 8.0 reaction mixture. The second highest activity was obtained by S-Tricine-N pH 8.0 extraction medium and reaction mixture.

• Korean Journal of Medicinal Crop Science
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• v.22 no.1
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• pp.38-45
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• 2014

This study was performed to investigate the physiological responses of Oplopanax elatus by water condition. Drought stress was induced by withholding water for 26 days. The results show that $P_{N\;max}$, SPAD, gs, E and Ci were significantly decreased with decreasing of soil moisture contents. However, AQY and WUE were decreased slightly only at 26 day. This implies that photosynthetic rate is reduced due to an inability to regulate water and $CO_2$ exchange through the stomatal. According to JIP analysis, ${\Phi}_{PO}$, ${\Psi}_O$, ${\Phi}_{EO}$ and $PI_{ABS}$ were dramatically decreased at 21 day and 26 day, which reflects the relative reduction state of the photosystem II. On the other hand, the relative activities per reaction center such as ABS/RC, TRo/RC were significantly increased at 26 day. Particularly, Dio/RC and DIo/CS increased substantially under drought stress, indicating that excessive energy was consumed by heat dissipation. These results of chlorophyll a fluorescence show that the sensitivity changes photosystem II activity. Thus, according to the results, O. elatus was exhibited a strong reduction of photosynthetic activity to approximately 10% soil moisture contents, and JIP parameters could be useful indicator to monitor the physiological states of O. elatus under drought stress.