Photochemical Activity Of Chloroplasts Research Articles

PHOTOSYNTHESIS OF WHEAT SEEDLINGS WHEN GROWN IN A MEDIUM WITH HEAVY METALS AND PECTIN

Pectins are considered as a means for cleaning reservoirs and soils from heavy metals due to their high adsorption properties. The aim of the study was to find out how the adding of pectins into the nutrient medium would affect the toxicity of heavy metals such as cadmium and zinc. It was found that cadmium at a concentration of 10-4 Mol and zinc at a concentration of 5 mMol inhibited the accumulation of biomass by plants of 10-day durum wheat seedlings (Triticum durum Desf.). Pectins mitigated this effect, but to a small extent. In addition, there was a slight increase in the proportion of roots in seedlings of the variant with heavy metals and pectin. The leaf area of the seedlings also decreased under the influence of heavy metals, young leaves suffered the most. The addition of pectins had a negative effect on the formation of the leaf surface, and a decrease in this indicator was noted. It has been shown that pectins contribute to an increase in the content of organic carbon in wheat plants, while the content of the main pigments of photosynthesis decreases. However, in variants with pectins, the photochemical activity of chloroplasts is maintained at a higher level than in solutions with heavy metals only.

Influence of sodium chloride on morphophysiological characteristics of wheat and maize plants

Aim. The effect of sodium chloride on the physiological and biochemical parameters of wheat and maize genotypes, the identification of salinity-resistant varieties was studied. Wheat and maize plants were grown in pots in the soil with the addition of 0.5 % sodium chloride. To create new salt-tolerant varieties of wheat and maize, a comparative analysis of the morphophysiological parameters plants was carried out. Methods. Morphophysiological parameters such as growth, chlorophyll and carotenoid content, photochemical activty of chloroplasts and PSII activity have been studied in wheat and maize plant. Results. The effect of salt on the amount of chlorophyll a, chlorophyll b, and carotenoids, which are the main physiological indicators, is manifested in different ways in both plants. When studying salt-tolerance of plants, differences were detected in the relative amounts of chlorophyll (a+b), carotenoids, as well as the photochemical activity of chloroplasts and efficiency of PS 2. Conclusions. Among the varieties, according to all morphophysiological parameters, the most tolerant to the action of salt was the soft wheat variety Mirbashir-128, and the corn hybrid Belaya x Gurur.

Influence of light intensity and its spectral composition on photosynthetic activity of cucumber Cucumis sativus under fusarium wilt

The responses of cucumber chloroplasts of the Kustovoi variety formed under lighting of different intensity (6000 and 11 000 lx) or under LED lighting with a predominance of red light and far red light to infection with fungus Fusarium oxysporum were studied. The amount of chlorophylls and carotenoids in chloroplasts formed at low light increased in 72 h after infection, and at high light a significant increase in pigment catabolism was observed. Under fusarium wilt, the violaxanthin cycle was not involved in the conditions of the studied light range, and the photochemical activity of chloroplasts did not depend much on the level of illumination. The predominance of red light or far red light caused an increase in both chlorophylls and carotenoids content in terms of the dry mass of the leaf compared to their content in plants grown on white light. Infection on white light and red light caused an increase in the total content of chlorophylls and carotenoids, and a decrease in these parameters relative to healthy plants was noted on far red light. Fusarium wilt led to a decrease in photochemical activity and electron transport of photosystem I (by 20 %) in chloroplasts on red light and far red light. A decrease in the functional efficiency of photosystem II was also observed, most likely due to irreversible changes in pigment-protein complexes with two types of LED lighting. Various mechanisms of the response of cucumber chloroplasts to pathogen infection are discussed, depending on the light conditions of the formation of photosynthetic membranes.

Evaluation of physiological, biochemical and yield indicators of wheat and maize genotypes exposed to sodium chloride

Aim. Study the effect of sodium chloride on the physiological and biochemical characteristics of wheat and maize genotypes, to identify varieties tolerant to salinity. To create new salt-tolerant varieties of wheat and maize, a comparative analysis of the physiological and biochemical parameters of the parental and hybrid plants was carried out. Methods. Physiological parameters such as chlorophyll content, relative water content, and PSII activity have been studied in parental forms and hybrids. Results. When studying salt-tolerance of hybrids and parental forms, differences were detected in the relative amounts of chlorophyll (a+b), carotenoids, RWC, as well as the photochemical activity of chloroplasts. The effect of salt on the amount of chlorophyll a, chlorophyll b, and carotenoids, which are the main physiological indicators, is manifested in different ways in both hybrids and parental forms. Conclusions. Based on the physiological indices determined during the grain filling stage, the highest tolerance was manifested by the parental forms, Garabagh, Gobustan, and the hybrids, ♀Garabagh×♂Gobustan, ♀Garabagh×♂Mirbashir, ♀Garabagh×♂Sharg. Under the action of salt in all genotypes of corn found a slight increase in the content of soluble sugars. The highest sugar content was observed in the hybrid Zagatala 68 x Gurur.

The influence of low-temperature on the photochemical activity of chloroplasts and activity of antioxidant enzymes in maize leaves

The effects of low growth temperature on the activities of photosystems (PS) 1 and 2 and antioxidant enzymes superoxide dismutase (SOD), ascorbate peroxidase (APX), glutathione reductase (GR) and catalase (CAT) in leaves of various maize inbred and hybrid genotypes (parental lines, F1 hybrids, F2 and backcross generations) were investigated. Considerable decrease of the PS 2 activity (contrary to the activity of PS 1) due to low-temperature stress was observed in the majority of genotypes/generations examined. The GR, APX and SOD activities markedly increased due to chilling, whereas the activity of CAT showed lesser changes which depended on the genotype/generation analysed. The higher susceptibility of the inbred line 2013 to low temperature was transmitted to further generations in case this line was used as the maternal parent. The intraspecific variability in photosynthetic and antioxidant parameters was caused particularly by the dominance (negative or positive), however, the level of the expression of this effect often changed after low-temperature stress and was probably the cause of the increase in the positive F1 heterosis observed in this case. Other genetic effects (e.g. the additivity, and particularly the additive or dominant maternal effects) were also found to contribute to the intraspecific variability in parameters analyzed. The dominant maternal effects possibly played an important role in maintaining positive heterosis in F2 generation.

Characterization of chlorophyll deficient mutants of pea

A series of 17 nuclear and 1 non-mendelian pea mutants of the chlorotica and chlorina phenotypes were characterized by oxygen evolution capacity of the leaves and polypeptide composition of the photosynthetic membranes. Four chlorina mutants lack oxygen evolution capacity. Changes in the polypeptide pattern of the membranes were detected for 6 of the mutants. The ultrastructure and the photochemical activities of chloroplasts from the non-mendelian mutant and 10 of the nuclear mutants were also investigated. Abnormal membrane organizations were observed in all cases, except for one chlorina mutant. Chloroplasts from 3 mutants that lack oxygen evolution capacity do not possess detectable photosystem (PS) II activity. Altered PS I and PS II activities were observed for the other mutants that were tested. The low temperature fluorescence emission spectrum of leaves from the Chl b- and grana-rich mutant chlorotica-5824 have strongly reduced peaks at 685 and 695 nm, while that of leaves from the Chl b- and grana-deficient mutant chlorina-5535 indicates a reduction in the emission at 685 nm and at the long-wavelength maximum. The long-wavelength band is located at 734 nm for the wild type, 730 nm for chlorotica-5824 and 716 nm for chlorina-5535.

Changes in the photosynthetic apparatus during fusarium wilt of tomato

Development of fusarium wilt was studied in 4-to 6-month-old tomato plants (Lycopersicon esculentum L., cv. Kunera). It was shown that the development of this disease could follow two patterns. When the wilt developed slowly (type I disease), the mycelium of Fusarium oxysporum fungus partly blocked the xylem and grew extensively within parenchyma. When the wilt developed fast (type II syndrome), the occlusion of both xylem and phloem was observed; the xylem sap circulation was suppressed and, consequently, tomato plant tissues were dehydrated. The development of type I and type II diseases led to suppression of photosynthetic activity in plants. In the case of slow wilt (type I), both light and dark stages of photosynthesis were damaged. This was evident from the decrease in the effectiveness of light harvesting and charge separations in the reaction centers of photosystem II (PSII), suppression of electron transport at the acceptor side of PSII, and the decrease in activity of Rubisco. In the case of fast wilt (type II), the Rubisco activity did not change, and photochemical activity of chloroplasts was suppressed to a smaller degree than during type I fusarium wilt. The decrease in the rate of linear electron transport in tomato leaves was mostly due to inhibition of electron flow at the acceptor side of PSII. The data obtained suggest that photosynthetic activity in tomato plants is suppressed by different mechanisms depending on the developmental pattern of fusarium wilt.

Impaired Photosynthesis in Cucumber (Cucumis sativus L.) by High Root-zone Temperature Involves ABA-induced Stomatal Closure and Reduction in Ribulose-1,5-bisphosphate Carboxylase/oxygenase Activity

Effects of high root-zone temperature (RT) on ABA content, photosynthesis and its related parameters in cucumber (Cucumis sativus L., cv. Suyo) were investigated. Plants were grown in water culture at a RT of either 30°C or 3°C for 10 days. Other growth conditions were 30/25°C air temperatures (day/night), a 14-hr photoperiod, and a light intensity of 250 μmol·m·s-1. Plant growth was severely inhibited at 38°C RT as compared with that at 30°C RT. At 38°C RT, leaves did not wilt and the leaf color was normal green, but showed a marked increase in ABA content after day 6 with a significant decrease in stomatal leaf conductance. In both RT treatments, leaf water potential declined at day 6, which was more pronounced at 38°C RT than at 30°C RT, but the difference was relatively small. The photochemical activity of chloroplasts was not affected by high RT. However, the CO2 exchange rate (CER) of leaves decreased linearly after day 4 in the high RT treatment. Peeling the epidermis of the abaxial leaf surface to eliminate the stomatal limitation to CER resulted in a significant but not complete recovery of CER, indicating that the high RT limited CER through a decrease in not only stomatal aperture but also photosynthetic capacity of mesophyll cells. After day 6 of high RT treatment, ribulose-1, 5-bisphosphate carboxylase/oxygenase (Rubisco) exhibited a gradual decrease in the initial level and the activation state. The results indicate that ABA-induced stomatal closure and reduction in the activation state of Rubisco are responsible for impaired photosynthesis in cucumber grown at elevated RT.

High irradiance-induced changes in carotenoid composition and increase in non-photochemical quenching of Chl a fluorescence in primary wheat leaves

The effect of acclimation to high irradiance stress (HIS, 250 Wm-2) in wheat leaves grown under three different irradiances was investigated by HPLC analyses of pigments, chlorophyll a fluorescence parameters and photochemical activities of chloroplasts. Significant loss of beta-carotene was observed compared to the xanthophylls in all three types of seedlings exposed to HIS. However, the effect of HIS on neoxanthin and lutein contents was not significant. The loss of partial electron transport (Asc-DCPIP to MV, PSI activity) was less than the whole chain (H2O to MV) and PS II activity (H2O to DCPIP) suggesting that PS I is less susceptible to HIS compared to PS II. The percent of reductions in Fv/Fm and phi PS II were less in plants grown under high irradiance (HI-1, 30 Wm-2 and HI-2, 45 Wm-2) compared to those grown under moderate irradiance (MI, 15 Wm-2). On the other hand, the percent of NPQ increased more in the leaves of HI plants compared to the leaves of MI when exposed to HIS which suggests a more efficient non-radiative dissipation of excess excitation energy in HI plants compared to MI. These observations suggest that plants grown under relatively high irradiance are better adapted to HIS condition.

Correlation Analysis of Triticale Morphology, Chlorophyll Content and Productivity

In some lines and F1 hybrids of winter hexaploid triticale (xTriticosecale Witt.), significant positive associations were found amongst leaf anatomy, plant morphology, chlorophyll content, photochemical activity of chloroplasts, and photosynthetic or grain productivity. The data may be useful in practical triticale breeding.

Growth, photosynthesis, and uptake of heavy metals by barley and corn plants influenced by different methods of zeolite and phosphogypsum application

Natural zeolite can be used as a heavy metals adsorbent from phosphogypsum, applied as a soil amendment. We used barley and corn seedling to investigate the effect of different methods of zeolite and phosphogypsum application on (a) growth, photochemical activity of chloroplasts and chlorophyll content; (b) uptake of strontium (Sr), calcium (Ca), and cadmium (Cd) in relation to photosynthetic activity, and content of these elements in the soil. Phosphogypsum was found to negatively influence the growth and development of the seedlings, affecting their morphology traits, biomass production and photosynthetic activity. Therefore, the application of phosphogypsum together with natural zeolite, according to the recommended technique, “in mixture”; completely erased consequences of phosphogypsum treatment. Uptake of Sr by barley plants was noticed to be highly dependent on photosynthetic activity and leaf area, however, there was no close correlation found between the content of water soluble Sr in the soil and its accumulation in plants.

Organisation of Photosynthetic Apparatus of Triticale in Relation to Productivity

Chlorophyll (Chl) content, photochemical activity of chloroplasts as well as photosynthetic and crop productivity were studied in different winter hexaploid Triticale (xTriticosecale Witt.) lines and their F1 hybrids. Heterosis enhanced Chl content, photosynthetic potential, photosynthetic productivity, and grain yield only in several F1 hybrids of Triticale. Indication in some genotypes of close correlations among morphological structure, Chl content, photochemical activity of chloroplasts, photosynthetic potential, and plant productivity may be used in breeding practice of Triticale.

Effects of zeolite and phosphogypsum on growth, photosynthesis and uptake of Sr, Ca and Cd by barley and corn seedlings

Barley and corn seedling were used to investigate the influence of zeolite and phosphogypsum on a) growth, photochemical activity of chloroplasts and chlorophyll content; b) content of water soluble Sr, Ca and Cd in the soil, and c) uptake of these elements in relation to photosynthetic activity, and content of these elements in the soil. Phosphogypsum was found to negatively influence the growth and development of the seedlings, affecting their morphological traits, biomass production and photosynthetic activity. Therefore, application of phosphogypsum combined with natural zeolite enabled a complete removal of the “side effects”; of phosphogypsum treatment. Furthermore, the application of zeolite was found to increase photosynthetic activity and biological yields of barley and corn plants. The results of our investigation showed the absence of close correlation between the content of water soluble Sr in the soil and its accumulation in plants. However, the uptake of Sr by barley plants was found to be highly dependent on their photosynthetic activity and leaf area.

Diurnal Fluctuations in Photochemical Activities of Chloroplasts in Field Grown Cyamopsis Tetragonoloba Seedlings

In field-grown Cyamopsis seedlings, distinct changes were found in the rates of photosystems (PS) 2 and 1 activities at different time of the day. Maximum PS2 activity was at around 11:00 h and decreased thereafter. On the contrary, PS1 activity continued to increase up to 14:00 h and declined in evening hours. Significant energy transfer from PS2 to PS1 was evident during the morning and evening hours of the day whereas a slow excitation of PS2 and energy transfer was favoured during noon hours.

Euploidy in Ricinus

The effects of nuclear genome duplication on the chlorophyll-protein content and photochemical activity of chloroplasts, and photosynthetic rates in leaf tissue, have been evaluated in haploid, diploid, and tetraploid individuals of the castor bean, Ricinus communis L. Analysis of this euploid series revealed that both photosystem II (2,6-dichlorophenolindophenol reduction) and photosystem I oxygen uptake (N,N,N',N'-tetramethyl-p-phenylenediamine to methyl viologen) decrease in plastids isolated from cells with increasingly larger nuclear complement sizes. Photosynthetic O(2)-evolution and (14)CO(2)-fixation rates in leaf tissue from haploid, diploid, and tetraploid individuals were also found to decrease with the increase in size of the nuclear genome. Six chlorophyll-protein complexes, in addition to a zone of detergent complexed free pigment, were resolved from sodium dodecyl sulfate-solubilized thylakoid membranes from cells of all three ploidy levels. In addition to the P700-chlorophyll a-protein complex and the light-harvesting chlorophyll a/b-protein complex, four minor complexes were revealed, two containing only chlorophyll a and two containing both chlorophyll a and b. The relative distribution of chlorophyll among the resolved chlorophyll-protein complexes and free pigment was found to be similar for all three ploidy levels.

Ptiotosynthetic activity and chloroplast membrane polypeptides in euploid cells of Ricinus

The possible effects of altered nuclear complement size on the poiypeptide composition and photochemical activity of chloroplasts in haploid, diploid, and tetraploid cells, of Ricinus communis L. have been evaluated. The electron transport capacity in isolated chloroplasts decreases with the increase in nuclear genome size. Both Photosystem II (DCPIP reduction) and Photosystem 1 oxygen uptake (TMPD to methyl viologen) activities were lower in plastid preparations from tetraploid individuals than in diploid and haploid cell preparations. Photosynthetic O2‐evolution and CO2‐fixation rates in leaf tissue from euploid individuals were also found to decrease with the increase in size of the nuclear genome. Specific activity levels of RuBP‐carboxylase were observed to increase with ploidy. Electrophoretic examination of the poiypeptide composition of thylakoid membranes from haploid, diploid, and tetraploid celis revealed no difference in the relative proportions of the constituent polypeptides of these membranes. The regulation of chloroplast development and the basis for altered plastid function in the presence of altered nuclear genome size are discussed.

Effect of Water Stress on Photochemical Activity of Chloroplasts during Greening of Etiolated Barley Seedlings

Effect of Water Stress on Photochemical Activity of Chloroplasts during Greening of Etiolated Barley Seedlings

Interference of herbicides with photochemical activities of chloroplasts in six shrub species

Summary:The effects of paraquat and 2,4,5‐T on the photochemical activities of chloroplasts from the leaves of the woody species Carissa spinarum, Maba buxifolia, Flacourtia sepiaria, Chomelia asiatica, Gymnosporia emarginata and Dodonaea viscosa were investigated by comparing the effects on isolated chloroplasts from untreated leaves with those on chloroplasts isolated from herbicide‐sprayed plants. DCPIP and NADP reduction of chloroplasts incubated in paraquat or 2,4,5‐T solution was inhibited, whereas that of chloroplasts isolated from most species sprayed with these herbicides was enhanced after 24 and 48 h. The enhancement was smaller or disappeared after 72 h. The cyclic and noncyclic photophosphorylation rates were suppressed in chloroplasts isolated from herbicide‐treated plants, and also in those from most untreated plants incubated in the herbicide solutions. The differences in reactions of chloroplasts from herbicide‐treated and untreated plants are discussed.

Chloroplast membrane alterations in triazine-resistant Amaranthus retroflexus biotypes

The effectiveness of diuron, atrazine, procyazine, and cyanazine were compared in controlling growth of redroot pigweed (Amaranthus retroflexus L.) in hydroponic culture. A very marked differential inhibition response was observed for atrazine between resistant and susceptible biotypes. Procyazine and cyanazine exhibited less dramatic differential responses, whereas diuron was equally effective in controlling growth in both biotypes. Photosystem II activity of chloroplasts from both triazine-resistant and triazine-susceptible biotypes was inhibited by diuron but only the chloroplasts from triazine-susceptible biotypes were inhibited significantly by atrazine. The photochemical activity of chloroplasts from triazine-resistant biotypes was partially resistant to procyazine or cyanazine inhibition. The parallel lack of diuron differential effects, partial procyazine and cyanazine differential response, and very marked atrazine differential response in both whole plant and chloroplast assays indicates that the chloroplast is the site of selective herbicide tolerance in these triazine-resistant redroot pigweed biotypes.Photosystem II photochemical properties were characterized by analysis of chlorophyll fluorescence transients in the presence or absence of herbicides. Data with susceptible chloroplasts indicated that both diuron and atrazine inhibit electron flow very near the primary electron acceptor of photosystem II. Only diuron altered the fluorescence transient in resistant chloroplasts. In untreated preparations there were marked differences in the fast phases of the fluorescence increase in resistant vs. susceptible chloroplasts; these data are interpreted as showing that the resistant plastids have an alteration in the rate of reoxidation of the primary photosystem II electron acceptor. Electrophoretic analysis of chloroplast membrane proteins of the two biotypes showed small changes in the electrophoretic mobilities of two polypeptide species. The data provide evidence for the following herbicide resistance mechanism: genetically controlled modification of the herbicide target site.

Herbicidal interference with the photochemical activities of chloroplasts ( in vivo and in vitro) of certain crop and weed species

The independent modes of action of diuron and atrazine on the photochemical activities of chloroplasts ( In vivo and in vitro) from the leaves of crop plants Pisum sativum and Pennisetum typhoides and the weeds Amaranthus viridis and Cyperus rotundus were investigated. Hill reaction activity (DCPIP photoreduction) of in vivo chloroplasts (chloroplasts isolated from herbicide-sprayed plants) was unaffected by treatment at sublethal or intermediate levels of diuron or atrazine while that of in vitro chloroplasts (chloroplasts incubated in the required herbicidal concentration) was severely inhibited. The ferricyanide catalyzed noncyclic photophosphorylation was markedly reduced in both the in vivo and in vitro chloroplast systems. N-Methyl phenozonium sulfate (PMS)-mediated cyclic photophosphorylation was inhibited in the in vivo system while a pronounced enhancement of activity was noticed in the in vitro chloroplasts. The rate of NADP + photoreduction was severely inhibited in the in vitro chloroplasts. The unaffected in the in vivo system. The herbicidal effects on the photoreactions of isolated chloroplasts were compared with chloroplasts isolated from herbicide-sprayed plants.