scholarly journals Morphological, anatomical, physiological and biochemical adaptations of Pittosporum tobira (Thunb.) W.T.Aiton and P. heterophyllum Franch. to the illumination level

2019 ◽  
Keyword(s):  
Photosynthetic Apparatus ◽  
Illumination Level ◽  
Low Light ◽  
Interspecific Differences ◽  
Common Trend ◽  
Sensitive Organ ◽  
Anatomical Adaptations ◽  
Intense Solar Radiation ◽  
Diagnostic Indicator ◽  
Physiological And Biochemical

Anatomical, morphological, physiological and biochemical adaptations of leaf as the most ecologically sensitive organ in the species P. tobira and P. heterophyllum, grown in the zones of greenhouse complex with different degree of illumination (1 zone – the level of illumination is 100–300 lx, zone 2 – 3000–7000 lx, and zone 3 – more than 10 thousand lx).) were studied. We revealed the structural morphological and anatomical adaptations, which manifested in the increase of leaf structure xeromorphy (thickening of the leaf, adaxial epidermis and columnar parenchyma, increasing pubescence density) under conditions of high insolation. With a low level of illumination in plants of both species, the thickness of the lamina decreased, mainly due to the mesophyll – the number of layers of the columnar parenchyma and the size of the cells reduced. Interspecific differences in the content of photosynthetic pigments in both species studied were found. A common trend in plants under low light conditions was decrease of chlorophyll a compared with the control, whereas the concentration of chlorophyll b in the leaves of plants increased with shading and high insolation. The result of the adaptation of the photosynthetic apparatus of Pittosporum plants, which normalizes its functioning, is a decreasing chlorophyll index both during shading and intense solar radiation. The maximum is determined in the range of 3–7 thousand lx. Such light regime is optimal for plants of the species studied. The observed decreasing pigment index in P. heterophyllum leaves is considered as an adaptive response of more light-loving species of the genus to their cultivation in the shade. The dependence of the peroxidase activity in Pittosporum leaves on the illumination level was studied. Adaptive reactions manifested in changes of peroxidase fractional composition in the leaves of the plants grown in different conditions. The obtained results on the activation and inactivation of the enzymatic activity of free and cell wall-associated peroxidase are interesting for using as an additional diagnostic indicator of stress degree for the plants of the interiors. It was established that adaptive changes in experimental plants were determined by the origin of species and their ecological and biological features.

scholarly journals Compensation Mechanism of the Photosynthetic Apparatus in Arabidopsis thaliana ch1 Mutants

2020 ◽  
Vol 22 (1) ◽  
pp. 221
Author(s):  
Joanna Wójtowicz ◽  
Adam K. Jagielski ◽  
Agnieszka Mostowska ◽  
Katarzyna B. Gieczewska
Keyword(s):  
Light Stress ◽  
Photosynthetic Apparatus ◽  
Protein Composition ◽  
Mrna Levels ◽  
Chlorophyll B ◽  
Low Light ◽  
Plant Acclimation ◽  
Chlorophyll B Deficiency ◽  
Composition Changes

The origin of chlorophyll b deficiency is a mutation (ch1) in chlorophyllide a oxygenase (CAO), the enzyme responsible for Chl b synthesis. Regulation of Chl b synthesis is essential for understanding the mechanism of plant acclimation to various conditions. Therefore, the main aim of this study was to find the strategy in plants for compensation of low chlorophyll content by characterizing and comparing the performance and spectral properties of the photosynthetic apparatus related to the lipid and protein composition in four selected Arabidopsis ch1 mutants and two Arabidopsis ecotypes. Mutation in different loci of the CAO gene, viz., NW41, ch1.1, ch1.2 and ch1.3, manifested itself in a distinct chlorina phenotype, pigment and photosynthetic protein composition. Changes in the CAO mRNA levels and chlorophyllide a (Chlide a) content in ecotypes and ch1 mutants indicated their significant role in the adjustment mechanism of the photosynthetic apparatus to low-light conditions. Exposure of mutants with a lower chlorophyll b content to short-term (1LL) and long-term low-light stress (10LL) enabled showing a shift in the structure of the PSI and PSII complexes via spectral analysis and the thylakoid composition studies. We demonstrated that both ecotypes, Col-1 and Ler-0, reacted to high-light (HL) conditions in a way remarkably resembling the response of ch1 mutants to normal (NL) conditions. We also presented possible ways of regulating the conversion of chlorophyll a to b depending on the type of light stress conditions.

Changes in the Stoichiometry of Photosystem II Components as an Adaptive Response to High-Light and Low-Light Conditions during Growth

1986 ◽  
Vol 41 (5-6) ◽  
pp. 597-603 ◽  
Author(s):  
Aloysius Wild ◽  
Matthias Höpfner ◽  
Wolfgang Rühle ◽  
Michael Richter
Keyword(s):  
Photosystem Ii ◽  
Functional Organization ◽  
Photosynthetic Apparatus ◽  
High Light ◽  
Molar Ratio ◽  
Light Conditions ◽  
Low Light ◽  
Pigment System ◽  
Transport Chain ◽  
The One

The effect of different growth light intensities (60 W·m-2, 6 W·m-2) on the performance of the photosynthetic apparatus of mustard plants (Sinapis alba L.) was studied. A distinct decrease in photosystem II content per chlorophyll under low-light conditions compared to high-light conditions was found. For P-680 as well as for Oᴀ and Oв protein the molar ratio between high-light and low-light plants was 1.4 whereas the respective concentrations per chlorophyll showed some variations for P-680 and Oᴀ on the one and Oв protein on the other hand.In addition to the study of photosystem II components, the concentrations of PQ, Cyt f, and P-700 were measured. The light regime during growth had no effect on the amount of P-700 per chlorophyll but there were large differences with respect to PQ and Cyt f. The molar ratio for Cyt f and PQ between high- and low-light leaves was 2.2 and 1.9, respectively.Two models are proposed, showing the functional organization of the pigment system and the electron transport chain in thylakoids of high-light and low-light leaves of mustard plants.

Distribution and Effects of Bentazon in Crop Plants and Weeds

1982 ◽  
Vol 37 (10) ◽  
pp. 889-897 ◽  
Author(s):  
H. K. Lichtenthaler ◽  
D. Meier ◽  
G. Retzlaff ◽  
R. Hamm
Keyword(s):  
Electron Flow ◽  
Photosynthetic Apparatus ◽  
Crop Plants ◽  
Light Conditions ◽  
Low Light ◽  
Tolerant Plants ◽  
Variable Chlorophyll Fluorescence ◽  
Pigment Ratios ◽  
Kautsky Effect ◽  
Uptake And Transport

Abstract The inhibition of photosynthetic CO2-assimilation and of the variable chlorophyll fluorescence as well as uptake and transport of 14C-labelled bentazon and the possibilities for a herbicideinduced shade-type modification of the photosynthetic apparatus were investigated in bentazonsensitive weeds (Galium, Sinapis, Raphanus) and in the tolerant crop plants wheat and maize.1. In weeds the depression of photosynthetic CO2-assimilation is irreversible, whereas tolerant plants recover due to the metabolization of the active herbicide.2. A lower rate of uptake and transport of bentazon associated with its fast metabolization is the reason for the tolerance of crop plants towards bentazon.3. The transport of [14C]bentazon proceeds in the tracheary elements of the xylem. Uptake and transport of bentazon in the weeds are light dependent.4. The loss of variable fluorescence (Kautsky effect) in the leaves after root application o f bentazon proceeds much faster at high-light than at low light conditions and confirms the light-dependency of the bentazon transport.5. In the sensitive dicot weeds bentazon not only inhibits photosynthetic electron flow and depresses CO2-fixation but also induces the formation of shade-type chloroplasts which are less efficient in photosynthetic quantum conversion. This bentazon-induced modification of the photosynthetic apparatus (e.g. changes in ultrastructure, pigment ratios, and levels of chloro-phyll-proteins) contributes to the effectiveness of bentazon as a herbicide.

PHOTOACCLIMATION IN PHOTOSYNTHETIC MICROORGANISMS: AN ULTRASTRUCTURAL RESPONSE

1998 ◽  
Vol 46 (2) ◽  
pp. 141-146 ◽  
Author(s):  
Tamar Berner ◽  
Assaf Sukenik
Keyword(s):  
Light Intensity ◽  
Light Harvesting ◽  
Photosynthetic Apparatus ◽  
Typical Feature ◽  
Optimal Operation ◽  
High Irradiance ◽  
High Rate ◽  
Low Light ◽  
Low Light Intensity ◽  
Photosynthetic Microorganisms

Photosynthetic microorganisms are able to modify their chemical composition, cellular structure, and organization of their chloroplasts in response to the level of irradiance. The photosynthetic apparatus adjusts itself to any new light regime by changing the ultrastructural properties of the chloroplast to provide space and area needed to match other biochemical changes in order to optimize light harvesting and utilization. Acclimation to low light intensity is characterized by an increase in thylakoid number in cyanobacteria, and in the chloroplast volume in eukaryotic plants. In the Eukaryota, these changes allow the packaging of more thylakoids within this organelle to harbor the addition of photosynthetic complexes, i.e., light harvesting antennae, reaction centers, and electron transport components. These changes are essential for optimal operation of the photosynthetic apparatus at low light intensity, mainly to increase the absorption of light energy. Acclimation to high irradiance is characterized by a reduction of the surface density of thylakoid membranes and reduction in the specific volume of the chloroplast. The accumulation of storage bodies containing starch and lipids is yet another typical feature of high light acclimated cells in response to the high rate of photosynthetic activity.

scholarly journals Acclimatization of photosynthetic apparatus and antioxidant metabolism to excess soil cadmium in Buddleja spp.

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Weichang Gong ◽  
Bruce L. Dunn ◽  
Yaqing Chen ◽  
Yunmei Shen
Keyword(s):  
Quantum Yield ◽  
Photosynthetic Apparatus ◽  
Photochemical Quenching ◽  
Effective Quantum Yield ◽  
Antioxidant Metabolism ◽  
Cellular Reactive Oxygen Species ◽  
Soil Cadmium ◽  
Non Photochemical Quenching ◽  
Cd Translocation ◽  
Physiological And Biochemical

AbstractHeavy metal (HM) pollutants can cause serious phytotoxicity or oxidative stress in plants. Buddleja L., commonly known as “butterfly bushes”, are frequently found growing on HM-contaminated land. However, to date, few studies have focused on the physiological and biochemical responses of Buddleja species to HM stress. In this study, potted seedlings of B. asiatica Lour. and B. macrostachya Wall. ex Benth. were subjected to various cadmium (Cd) concentrations (0, 25, 50, 100, and 200 mg kg−1) for 90 days. Both studied Buddleja species showed restricted Cd translocation capacity. Exposure to Cd, non-significant differences (p > 0.05) were observed, including quantum yield of photosystem II (PSII), effective quantum yield of PSII, photochemical quenching and non-photochemical quenching in both species between all studied Cd concentrations. Moreover, levels of cellular reactive oxygen species (ROS) significantly declined (p < 0.05) with low malondialdehyde concentrations. In B. asiatica, high superoxide dismutase and significantly enhanced (p < 0.05) peroxidase (POD) activity contributed greatly to the detoxification of excess ROS, while markedly enhanced POD activity was observed in B. macrostachya. Additionally, B. macrostachya showed higher membership function values than did B. asiatica. These results suggested that both Buddleja species exhibited high Cd resistance and acclimatization.

scholarly journals Physiological and Biochemical Properties of Potato (Solanum tuberosum L.) in Response to Ozone-Induced Oxidative Stress

Agronomy ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1745
Author(s):  
Ewa Szpunar-Krok ◽  
Marta Jańczak-Pieniążek ◽  
Dagmara Migut ◽  
Karol Skrobacz ◽  
Tomasz Piechowiak ◽  
...  
Keyword(s):  
Solanum Tuberosum L ◽  
Crop Protection ◽  
Photosynthetic Apparatus ◽  
Visual Assessment ◽  
Biochemical Properties ◽  
Potato Plants ◽  
Total Antioxidant ◽  
Physiological And Biochemical ◽  
Safe Dose ◽  
Physiological And Biochemical Properties

We investigated the changes in the physiological and biochemical properties of potato plants exposed to differing ozone (O3) concentrations (5 ppm, 10 ppm) and exposure times (2, 4, 8, 12, 16 min) to determine the safe dose that could be used in crop protection programs. We measured the gas exchange, relative chlorophyll content, chlorophyll fluorescence and total antioxidant capacity in potato leaves exposed to O3 fumigation. The fresh weight (FW) of the aboveground part of the plants and a visual assessment of plant condition were determined after the end of the experiment. The plants were given two O3 treatments and measurements were carried out four times: on the 1st and 7th day after treatment. We conclude that O3 exposure time had a greater impact on the reduction in the efficiency of the potato photosynthetic apparatus than O3 concentration. Research has showed that O3 in 5 ppm concentration for 2 and 4 min and 10 ppm for 2 min increased the efficiency of the photosynthesis and antioxidant activity in leaf processes, and these doses could be taken into account in further research on the potential for using O3 in potato protection.

scholarly journals Comparative analysis of methods for keypoint detection in images with different illumination level

2018 ◽  
Vol 239 ◽  
pp. 01028
Author(s):  
Aleksei Makarov ◽  
Marina Bolsunovskaya ◽  
Olga Zhigunova
Keyword(s):  
Comparative Analysis ◽  
Illumination Level ◽  
Image Stitching ◽  
Light Conditions ◽  
Night Time ◽  
Low Light ◽  
Camera System ◽  
Keypoint Detection ◽  
Series Of Experiments

This article presents a comparative analysis of methods for keypoint detection that is a part of the research on the development of a surround camera system for large vehicles. Since the night time is the most dangerous for driving and the most difficult for image stitching, particular attention will be given to keypoint detection and image stitching in low light conditions. A comparative analysis of methods for keypoint detection has been made, a relevant technique has been developed and a series of experiments has been conducted to detect keypoints using the SURF, MSER, BRISK, Harris, FAST, and MinEigen methods. During the research, a search for identical keypoints for a pair of images, an analysis of their number and different methods of image stitching at different illumination levels were carried out. The results of the experiments are shown in graphs and tables.

Photosynthetic Utilisation of Lightflecks by Understory Plants

1988 ◽  
Vol 15 (2) ◽  
pp. 223 ◽  
Author(s):  
RW Pearcy
Keyword(s):  
Photosynthetically Active Radiation ◽  
Co2 Fixation ◽  
Photosynthetic Apparatus ◽  
Continuous Light ◽  
Stomatal Opening ◽  
Carbon Gain ◽  
Light Activation ◽  
Low Light ◽  
Active Radiation ◽  
Induction State

The light environment in forest understories is highly dynamic because the weak shade light is period- ically punctuated by lightflecks lasting from a second or less to tens of minutes. Although present for only a small fraction of the day, these lightflecks can contribute more than two-thirds of the photosynthetically active radiation. Several factots are of importance in determining the capacity of a leaf to utilise lightflecks. Following long low-light periods the induction state of the photosynthetic apparatus is limiting. During induction, 20-60 min may be required before maximum assimilation rates are reached due first to a light activation requirement. of ribulose-1,5-bisphosphate carboxylasel oxygenase and later to the light-induced stomatal opening. Continuous light is not required and induction occurring during a series of lightflecks results in higher carbon gain for later as compared to earlier lightflecks. Post-illumination CO2 fixation resulting from utilisation of metabolite pools built up during the lightfleck can significantly enhance carbon gain during short (5-20 s) lightflecks. The carbon gain of a leaf in response to a lightfleck is a consequence of the limitations imposed by induction state plus the enhancements due to post-illumination CO2 fixation. In the field, this will depend on the frequency and duration of the lightflecks and the duration of the intervening low-light periods.

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