• The Korean Journal of Ecology
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• v.28 no.2
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• pp.105-112
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• 2005

Environmental factors such as light and low $CO_2$ concentrations trigger events which may result in stomatal opening. Stomatal aperature is largely controlled by the solute contents of guard cells, but not exclusively, by through changes in their content of potassium salts, with $K^+$ balanced either by $Cl^-$ or malate, depending on the species and conditions. However, how these signals are sensed and how they are transduced into driving the ion fluxes that control stomatal movements is not still fully understood. The basic role of stomata is regulating transpiration and photosynthesis. Photosynthesis plays a central role in the physiology of plants and an understanding of its response to light is, therefore, critical to any discussion of how plants sense and respond to light. It had been proposed that the evidences pointed three possible mechanisms for the light response. Firstly, there is a direct response of stomata to light. Secondly. there is an indirect response of stomata to light through the effect of $CO_2$. Lastly, there are some evidences for a third effect of light on stomata. However, attempts to investigate how these three possible mechanisms explained in detail in response to light have not been made. Therefore, this study is examined the differences among these three possible mechanisms.

• Korean Journal of Environmental Biology
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• v.20 no.1
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• pp.78-84
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• 2002

The effects of light and darkness on stomatal aperture and guard cell apoplastic pH in the intact leaf and in the isolated epidermal strips of Commelina communis have been investigated. Stomata in the intact leaf opened wide in the light. In contrast, stomata in the isolated epidermal strips did not respond clearly to light. To eucidate the relationship between the stomatal aperture and the guard cell apoplastic pH, apoplastic pH was measured. In the light the guard cell wall of intact leaf was acidified by pH 1.9 units, falling from pH 7.3 to pH 5.4 in the first 10 minutes. On the contrary, apoplastic pH of isolated epidermal strips changed slowly from pH 7.3 to pH 6.9 at 20 min. Stomata in the intact leaf closed rapidly in the dark. On the other hand, stomata in the isolated epidermal strips failed to close in dark. There was a slow increase in apoplastic pH on transfer to the dark after incubation for 1.5 h in the light and the level observed before the experiment was regained after around 40 min. When the isolated epidermal strips were transferred to the dark, apoplastic pH maintained a uniform level of around pH 7.2-7.4. These results indicate that the mechanism of stomatal opening and closing from isolated epidermal strips and intact leaves could be different.

• Korean Journal of Environment and Ecology
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• v.30 no.1
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• pp.130-134
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• 2016

How does $CO_2$ affect on the stomatal mechanism? The mechanism of stomatal opening by $CO_2$ is not clear as it is difficult to see $CO_2$ effect on light-induced stomatal opening. Furthermore, stomata may react differently according to the concentration of $CO_2$. The significance of the possible endogenous rhythms must consider to understand on $CO_2$-related response. It is clear that $CO_2$ has an effect on the accumulation of osmotic materials which determines the degree of stomatal apertures because it is known that stomata open in the condition of the reduced $CO_2$ concentration. However, it is not fully understood how $CO_2$ leads to the stomatal opening. It has been thought that $CO_2$ can not affect on the ion fluxes which determines the increase of osmotic potential in guard cells. However, in this study, the changes of guard cell membrane permeability by $CO_2$ have been focused on. There are many reports that $CO_2$ related reactions are dominant when the leaf is exposed to certain a mount of $CO_2$. The hypothesis of the stomatal opening by light is based on the increase of osmotic materials in guard cells including $K^+$, $Cl^-$, sucrose and $malate^{2-}$. It was reported that $CO_2$ induced a big hyperpolarization indicating that $H^+$ was extruded to the cell outside. It was also found that $CO_2$ caused guard cell membrane hyperpolarization in the intact leaf up to 3 or 4 times higher than that of light induced membrane hyperpolarization. These results represent that $CO_2$ can affect on the change of physical characteristics which affects on the change of the membrane permeability.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.29 no.3
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• pp.267-274
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• 1984

This experiment was carried out to investigate the stomatal aperture of wheat variety 'Chokwang' grown in the two different nitrogen level. Stomatal aperture was measured at the maximal tillering, shooting, booting, flowering and grain filling stages. Stomatal aperture in leaf blades gradually increased in accordance with the successive leaf growth. The maximal opening of stomata was observed at flowering stage and around noon in a day, but stomata closed around six o'clock in the afternoon. Stomata opened wider in the high nitrogen application than in the low nitrogen and their effects were the highest at the booting and flowering stage. Diurnal course at stomatal aperture of upper leaves was wider than that of lower leaves regardless of growth stages. Positive correlation (r=0.66$^{**}$) appeared between nitrogen content in leaf blades and stomatal aperture. The leaves of low position and the developing leaves showed smaller stomatal aperture than the full expanded top leaves irrespective of leaf stages. Water content of leaf, root weight and root activity were increased by the nitrogen application and thus considered as factors increase the stomatal aperture.ication and thus considered as factors increase the stomatal aperture.

• Journal of Plant Biology
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• v.29 no.1
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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.

• Proceedings of the Zoological Society Korea Conference
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• 1996.10a
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• pp.187.1-187
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• 1996

No Abstract, See Full Text

• KOREAN JOURNAL OF CROP SCIENCE
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• v.40 no.5
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• pp.556-561
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• 1995

Persisent circadian rhythms in carbon assimilation, stomatal conductance and soluble carbohydrate concentration were investigated during grain filling period in rice plant transferred from a natural photoperiod to constant conditions. A weak rhythm in photosynthesis, measured as carbon assimilation, and stomatal opening, as conductance to water vapor, with a period of approximately 24-hours, occurred under constant condition. Carbon assimilation and stomatal conductance reached maximum values near noon and minimum values near midnight during the early stage (until 72-hour) after transferring to constant condition, and then the amplitude and phase were changed slowly, the rhythms with little damping, reaching maximum values near midnight and minimum values near noon during 96~120-hours after transferring. However, photosynthesis in plants grown for 14days after anthesis under constant moderate light(day and night) did not oscillated in constant condition unlike plants grown under a cycle of light and darkness. These phenomenon was observed in soluble carbohydrate concentration in flag leaves as well. Evidences from several approaches indicate that endogenous rhythms of $CO_2$ assimilation, stomatal conductance and soluble carbohydrate concentration are closely couped with each other and particularly important to plants, which depend on the natural day-night cycle as a external signal.

• Korean Journal of Environmental Biology
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• v.19 no.1
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• pp.1-6
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• 2001

Many researchers have been studied with guard cell protoplasts and detached epidermis as they think that properly stabilized protoplasts and detached epidermis retain many of the properties of intact guard cells. However, some studies have shown that stomata in detached epidermis behave differently, both quantitatively and qualitatively, from those in the intact leaf. Stomata in the intact leaf are very sensitive to environmental factors such as light, $CO_2$ and osmotic stress, but stomata in detached epidermis are less sensitive to these factors than those in the intact leaf. The clearest evidence to suggest the different response between detached epidermis and intact leaf obtained from the experiments with heavy metal, cadmium. 3-weeks old Commelina. communis was transferred to and grown in Hoagland solution in the presence or absence of 5 mM $Cd^{2+}$ for 4 days. The application of $Cd^{2+}$ showed about 70% inhibition of stomatal conductance when measured at various light intensity (100-1,000 $\mu$mole $m^{-2}s^{-1}). However, stomata in detached epidermis floated on an incubation medium containing 100 $\mu$M $Cd^{2+}$ opened to a degree of about 8.38 fm, but the stomata treated with no cadmium opened to 3.74 ${\mu}{\textrm}{m}$. These results were unexpected as the intact leaf grown in a Hoagland solution containing cadmium showed very negative physiological responses. These results showed that stomata in detached epidermis and in the intact leaf could respond reversely. Therefore, it is possible that we now misunderstand how stomata open in real natural condition.

• Korean Journal of Agricultural Science
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• v.9 no.2
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• pp.453-460
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• 1982

In order to investigate the effect of $AgNO_3$ pretreatment on reducing $SO_2$ injury in leaves of Forsythia koreana, changes of pH, chlorophyll content, peroxidase activity, sulfur content, and stomatal behaviour in leaves were examined. 1. $AgNO_3$ sprayed at 200 ppm or above increased black spot development in lower epidermis of leaves. But pretreatment with 100 ppm $AgNO_3$ significantly reduced de foliation and visible injury rate of leaves exposed to $SO_2$. 2. $AgNO_3$ pretreatment prevented lowering pH and decreasing chlorophyll content induced by $SO_2$ injury in leaves. But both $AgNO_3$ pretreatment and $SO_2$ exposure increased peroxidase activity in leaves. 3. $AgNO_3$ pretreatment did not affect reducing $SO_2$ absorption and stomatal opening in leaves exposed to $SO_2$.

• The Plant Pathology Journal
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• v.35 no.2
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• pp.178-187
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• 2019

Plants are exposed to biotic stresses caused by pathogen attack and complex abiotic stresses including heat and drought by dynamic climate changes. To alleviate these stresses, we investigated two bacterial stains, H26-2 and H30-3 in two cultivars ('Ryeokkwang' and 'Buram-3-ho') of Chinese cabbage in plastic pots in a greenhouse. We evaluated effects of bacterial strains on plant growth-promotion and mitigation of heat and drought stresses; the role of exopolysaccharides as one of bacterial determinants on alleviating stresses; biocontrol activity against soft rot caused by Pectobacterium carotovorum subsp. carotovorum PCC21. Strains H26-2 and H30-3 significantly increased fresh weights compared to a $MgSO_4$ solution; reduced leaf wilting and promoted recovery after re-watering under heat and drought stresses. Chinese cabbages treated with H26-2 and H30-3 increased leaf abscisic acid (ABA) content and reduced stomatal opening after stresses treatments, in addition, these strains stably colonized and maintained their populations in rhizosphere during heat and drought stresses. As well as tested bacterial cells, exopolysaccharides (EPS) of H30-3 could be one of bacterial determinants for alleviation of tested stresses in Chinese cabbages, however, the effects were different to cultivars of Chinese cabbages. In addition to bacterial activity to abiotic stresses, H30-3 could suppress incidence (%) of soft rot in 'Buram-3-ho'. The tested strains were identified as Bacillus aryabhattai H26-2 and B. siamensis H30-3 based on 16S rRNA gene sequence analysis. Taken together, H26-2 and H30-3 could be candidates for both plant growth promotion and mitigation of heat and drought stresses in Chinese cabbage.