• Animal cells and systems
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• 제4권4호
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• pp.337-340
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• 2000

The photosynthetic and stomatal responses of several woody plants (Powlonia coreana, Firmiana simplex, Quercus acutissima Q. variabilis and Q. serrata) to SO$_2$ were investigated in order to understand their ecophysiological tolerance to $SO_2$ Of the plants, P, coreana showed the largest reduction in its photosynthesis in response to exposure of 0.4 ppm $SO_2$ for 20 h. Fumigation of 0.7 ppm $SO_2$ for 20 h caused complete leaf necrosis of P. coreana and f simplex, which made them unavailable for the measurement of photosynthesis. Q. variabilis exhibited the smallest reduction in photosynthesis following exposure of 0.7 ppm $SO_2$ for 20 h. Both stomatal- and non-stomatal inhibition of the plants by $SO_2$ were determined according to equations by lkeda et at. (1992). When exposed to 0.4 ppm $SO_2$ for 20 h, F. simplex and P. coreana showed the lowest stomatal and non-stomatal inhibition, respectively, while Q. variabilis and Q. serrata exhibited the lowest stomatal and non-stomatal inhibition, respectively, in response to 0.7 ppm $SO_2$ for 20 h. The data are discussed with regard to resistance mechanisms of other plants to $SO_2$ exposure and implications for restoration of declined Korean forests.

• The Korean Journal of Ecology
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• 제20권2호
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• pp.83-94
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• 1997

Stomatal closing by ozone and water stress could reduce further ozone injury by inhibition of ozone influx to the tissue. Direct effect of ozone on stomata can be explained from two aspects which are a stimulation of stomatal closing and an inhibition of stomatal opening. An increase of $Ca^{2+}$ influx into cytoplasm by ozone could stimulate potassium efflux ion channel and inhibits inward potassium ion channels. By this mechanism ozone could induce stomatal closing. On the other hand, ozone could inhibit stomatal opening by affecting the activity of $H^{+}$ dependent ATPase of the membrane in guard cells. This would inhibit proton efflux which precede stomatal opening. It is also possible that ozone could reduce the activity of photosynthesis in guard cells which lead to affect the production of osmotically active sugars and energy. Indirect effect of ozone to stomata is through the effect of $CO_2$ elevation as a result of damage of the photozynthetic machinery. This indirect effect is slower than the direct effect.

• 한국환경과학회지
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• 제6권2호
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• pp.125-131
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• 1997

The mechanism of stomatal closing in response to $O_2$ was indirectly investigated by using $H_2O_2$ which is the intermediate product of $O_2$ metabolites. Stomata in epidermal strips close in response to $H_2O_2$. The effect of $H_2O_2$ on stomatal closing was dependent on the concentration of $H_2O_2$. 10 ppm $H_2O_2$ showed a clear effect on stomatal closing and 1000 ppm $H_2O_2$ induced complete stomatal closing after the treatment of 3 hours. Stomatal closing by $H_2O_2$ in intact leaf was also observed by measuring the diffusion resistance with porometer. It was found that the stomatal closing by $H_2O_2$ was not mediated by $Ca^{2+}$, and that was a different result observed in stomatal closing by water stress. Reversely, $Ca^{2+}$ showed a great inhibition on stomatal closing. The leakage of K+ in epidermal strips was doubled in response to $H_2O_2$ when it was campared to the control. 10 ppm $H_2O_2$ decreased photosynthetic activity. Fv/Fm representing the activity of Photosystem II was reduced about 4 % in 10 ppm $H_2O_2$ and 8 % in 100 ppm $H_2O_2$ In the treatment of 1.5 hour. However, stomatal closing by 10 ppm $H_2O_2$ was reduced about 56 %. According1y, it can be suggested that stomatal closing by $H_2O_2$ is related with the decrease of photosynthetic activity, but it was chiefly induced by the change of the membrane permeability. Key words Commelina communis, stomatal closing, $H_2O_2$, $Ca^{2+}$, photosynthesis.

• Journal of Photoscience
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• 제9권2호
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• pp.158-161
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• 2002

UV-B radiation gives harmful effects on plants, such as production of several types of DNA lesions, and growth inhibition. On the other hand, plants have some protective mechanisms, including filtering effect due to accumulation of phenolic compounds in epidermal cells and reactivation of DNA lesions, which are enhanced by UV-B irradiation. We have investigated the mechanism of UV-B effects on plants using cucumber seedlings as plant materials. Cucumber plants were cultivated in an artificially lit growth chamber. Supplemental UV-B irradiation, of which intensity was almost equal to the level of natural sunlight, retarded the growth of first leaves. The growth retardation must result trom the inhibition of cell division and/or cell growth. Microscopical observation of leaf epidermis suggested that the growth retardation might be mainly caused by cell growth inhibition. The retardation was, however, restored within 2 or 3 days after the termination of UV-B irradiation. It is known that UV-B irradiation lowers the activity of photo system II (PS II). In the present experimental conditions, however, UV-B irradiation has little effect on PS II activity as estimated by chlorophyll fluorescence. The stomatal conductance, a major factor determining photosynthetic rate, of first leaves increased during the growth. The increase of stomatal conductance was suppressed by UV-B irradiation and restored by termination of the irradiation. It has not been clear, however, what mechanisms are involved in the suppression of increase of stomatal conductance.

• Journal of Plant Biology
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• 제29권1호
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• pp.41-51
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• 1986

The plants of Nicotiana tabacum L. cv. NC2326 were germinated in 10 cm D$\times$20 cm H polyethylene pot, and sand-cultured with Hoagland solution near by the window of laboratory room(26$\pm$5$^{\circ}C$). The growing plants were sprayed with various concentrations of ABA around 9 : 00 a.m. once in every two days for 12 weeks in summer. As the results, frequency of stomatal number, stomatal opening, chlorophyll content, respiration rate, and protein content in the leaves were decreased with the increasing of concentrations of ABA, respectively. The plant growth was inhibited by exogenous ABA, but leaf abscission was not found during the experimental period. The ratio of three to one in chlorophyll a to b was not altered by exogenous ABA. All the stomata were closed within three minutes by 100 $\mu\textrm{g}$ ml-1 ABA and within seven minutes by 1-10 $\mu\textrm{g}$ ml-1 ABA after the spraying of ABA, and then reopended after a few hours in 1-10 $\mu\textrm{g}$ ml-1 ABA and after 24 hours in 100 $\mu\textrm{g}$ ml-1 ABA. The polar movement of chloroplast within the guard cells was found in the higher concentrations of 10 and 100 $\mu\textrm{g}$ ml-1 ABA, but not found in the lower concentrations than 1 $\mu\textrm{g}$ ml-1 ABA. During the night and weak light, it was fond that the inhibition of respiration rate by the higher concentration of ABA was owing to firstly the stomatal closure by the spraying of ABA and secondly the decrease of stomatal frequency by the inhibition of stomatal development with exogenous ABA for the long period of 12 weeks. In the band number of leaf protein by the electrophoresis, most of the protein bands were disappeared by the higher concentration of 100 $\mu\textrm{g}$ ml-1 ABA, but were not altered by the lower concentration of ABA in comparison with control.

• 환경생물
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• 제18권2호
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• pp.263-268
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• 2000

$Cd^{2+}$이 닭의장풀의 분리표피와 온전한 잎의 기공개폐에 미치는 영향을 조사하였다. $Cd^{2+}$을 분리표피에 처리하였을 때 기공열림이 촉진되었다. 100$\mu$M$Cd^{2+}$처리시 기공은 8.38$\mu\textrm{m}$까지 열렸으나, 대조구는 3.74$\mu\textrm{m}$였다. 대조구의 기공 크기는 일반적으로 작게 열렸다. 따라서, 분리표피가 생리적으로 건강한지를 조사하기 위해, 살리실릭산(SA)과 앱시스산(ABA)을 분리표피에 처리하여 기공크기를 측정하였다. 100$\mu$M SA와 1$\mu$M ABA는 기공열림을 각각 14%와 28% 억제하였다. 비슷한 효과가 다른 중금속인 $Al^{3+}과 Ag^{2+}$에서도 발견되는지 이들에 대한 기공개폐 효과를 살펴보았다. $Al^{3+}과 Ag^{2+}$도 기공열림을 각각 19%, 41%촉진하였다. 카드뮴에 의한 기공열림 기작을 이해하기 위해 K+흡수에 대한 카드뮴의 효과를 조사하였다. $Cd^{2+}$, SA 그리고 ABA는 분리표피에서 K+흡수를 각각 98%, 28%, 34% 억제하였다. $Cd^{2+}$이 온전한 잎에 미치는 기공개폐의 영향을 조사하기 위해 3주간 성장한 닭의장풀을 Hoagland용액(0.5mM $Cd^{2+}$, 10mM $Cd^{2+}$)에서 수경 배양한 후 온전한 잎의 기공전도도를 측정하였다. 그 결과, 기공전도도는 대조구에 비해 5mM $Cd^{2+}$과 10mM Cd$^{2+}$에서 각각 51%, 70%감소되었다. 따라서, $Cd^{2+}$은 닭의장풀의 분리표피와 온전한 잎의 기공개폐에 상반된 반응을 보이며, 분리한 표피에서 $Cd^{2+}$에 의한 기공열림은 $Cd^{2+}이 K^+$ 흡수를 방해하고, 자신이 공변세포로 들어가 팽압을 유도한 결과로 사료된다.

• 환경생물
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• 제17권3호
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• pp.359-364
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• 1999

살리실릭산(SA)이 닭의장풀의 잎의 생장, 엽록소 함량, 광합성능, 기공전도도에 미치는 영향을 조사하였다. Hoagland 용액에 SA를 처리한 후 3주 동안 배양한 닭의장풀은 잎의 길이, 너비, 면적이 크게 감소하였다. 1 mM SA를 1, 2주 처리 시에 엽면적 생장이 약 10%억제되었으며, 3주 째에는 22%억제하였다. SA는 또한 2주 째는 47%그리고 3주 째는 53%엽록소 함량을 감소시켰다. SA를 처리한 샘플의 엽록소 a/b는 3주 째에 약 3으로 크게 증가하였다. SA를 분리 엽록체에 직접 처리하여 전자전달활성을 직접 측정하였다. PSII＋PSI, PSII 그리고 PSI활성에 SA가 영향을 주지 않았다. 이는 SA가 직접 광합성 기작에는 영향을 주지 않는 다는 것을 나타낸다. 그러나, SA를 오랜 기간 처리하면 광합성의 감소는 매우 뚜렷하게 관찰되었다. Hoagland 용액에 SA를 처리한 후 3주 동안 배양한 닭의장풀에 다양한 빛 광도(100~1000$\mu$mo1 m­$^2$S­$^1$)를 조사하면 약 23~65%의 광합성능의 저하가 나타났다. 기공전도도가 유사한 반응을 보여주었다. SA처리구의 기공은 거의 닫혔다. 여러 광조건에서 기공전도도가 같다는 것은 SA가 기공의 조절 기능을 상실하게 한 것으로 보여진다. 이들 결과들로부터 광합성능에 대한 SA의 효과는 SA자체에 의한 것이 아니라 간접적인 대사 경로를 통해 매개되는 것으로 추측된다.

• Journal of Ginseng Research
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• 제18권3호
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• pp.175-181
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• 1994

We studied the folilar wiping effects of antioxidants (ascorbate, glutathione and sodium azide), which effectively inhibited the chlorophyll bleaching or completely recorved the early stage of photosynthesis of Panax ginseng C.A. Meyer, on photosynthesis, stomatal resistance, free sugar, starch, and total saponin contents of ginseng under the excess light intensity (45 kLux) during 6 days. Ascorbate and glutathione, endogenous antioxidant, recovered photosynehtsis and stomatal resistance, and reduced the photoinhibition by the excess light intensity (45 kLux) on free sugar, starch and total saponin contents. But sodium azide, exogenous $^{1}O_2$ quencher, showed negative effect. Therefore, we assumed that carbohydrates and saponin metabolisms of ginseng by antioxidants (ascorbate, glutathione) were normal. For the reduction of inhibition by excess light in ginseng a program for the higher activation of antioxidants and antioxidative enzymes in ginseng leaf will be desirable. Key words Antioxidants, ascorbate, glutathione, Photoinhibition, ginseng.

• Journal of Ecology and Environment
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• 제36권4호
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• pp.255-265
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• 2013

This study was conducted to determine the extent of drought resistance based on physiological responses of Calystegia soldanella under water deficit. In order to investigate the changes of plant growth, stomatal density, photosynthesis, chlorophyll fluorescence, the contents of chlorophyll and carotenoid, osmolality, total ion contents, the contents of carbohydrate and proline, C. soldanella was grown under well watered and drought stressed conditions for 12 days. In this study, water-deficit resulted in remarkable growth inhibition of C. soldanella. The effect of water-deficit on plant growth was associated with low osmotic potential of soil. On day 12 after drought treatment, dry weight, relative water contents, number and area of leaves and stem length were lower than those of control. The stomatal conductance and net photosynthetic rate were significantly reduced in water stressed plant to regulate inner water contents and $CO_2$ exchange through the stomatal pore. Chlorophyll fluorescence and chlorophyll contents were not different in comparison with the control, indicating that the efficiency of photosystem II was not affected by drought stress. This results could be explained that water-deficit in C. soldanella limits the photosynthetic rate and reduces the plant's ability to convert energy to biomass. A significant increase in total ion contents and osmolality was observed on day 7 and day 12. Accumulation of proline in leaves is associated with the osmotic adjustment in C. soldanella to soil water-deficit. Consequently, this increase in osmolality in water stressed plant can be a result in the increase of ion contents and proline.

• 환경생물
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• 제18권1호
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• pp.63-67
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• 2000

$Cd^2+$이 닭의장풀의 엽록소 함유량, 기공 크기, 수분퍼텐셜, 이온 수송에 대한 효과와 기관내의 카드뮴의 축적에 대하여 조사하였다. 3주간 성장한 닭의장풀을 Hoagland용액(${\pm}5mM Cd^2+$)에서 4일 동안 수경배양하였다. 카드뮴은 식물의 뿌리, 줄기 그리고 잎 등 모든 기관에 축적되었다. 뿌리로부터의 거리와 잎의 나이 등이 카드뮴 분포를 결정짓는 가장 중요한 요소였다. 대부분의 $Cd^2+$이 뿌리로부터 가장 인접한 성숙한 첫 번째 잎에 축적되었다. 잎에 $Cd^2+$의 축적은 여러 생리적인 대사의 활성에 감소를 가져왔다. 카드뮴 처리는 70%의 엽록소 함량 감소를 가져왔으며, 엽록소 a/b비도 2로 감소하였다. $Cd^2+$은 또한 20%의 수분퍼텐셜을 감소시켰다. 카드뮴 처리는 여러 광도(100-l,000$\mu$mol $Em^-2s^-1$)에서 광합성 활성을 약 60% 감소시켰으며 기공전도도도 비슷한 반응을 보였다. 따라서, $Cd^2+$이 닭의장풀의 전반적인 생리적 활성을 감소시키거나 차단하는 것으로 추측된다.