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PubMed2006

Chlorophyll catabolism pathway in fruits of Capsicum annuum (L.): stay-green versus red fruits.

The aim of the present study is to investigate the chlorophyll catabolism pathway of wild-type red and stay-green mutants of Capiscum annuum (L.) fruits. In the wild-type red lines chlorophyll catabolism is concomitant with the start of carotenogenesis, whereas in the stay-green mutant lines the chlorophylls coexist with that process, even in over-ripe fruit. During the first stages of ripening, the chlorophyll a/chlorophyll b ratio is similar for both genotypes, but as ripening proceeds, the ratio in the stay-green lines becomes very high as a result of a blocked degradation of chlorophyll a while chlorophyll b is degraded at a normal rate. The absence of dephytylated chlorophylls in the wild-type lines distinguishes these from the mutant lines, in which there is a sequential accumulation of chlorophyllide a and pheophorbide a. Allomerized chlorophylls (13(2)-OH-chlorophyll a and b) have also been identified in the catabolic process of the mutant lines, but are absent from the wild type. Consequently, an alteration in pheophorbide a oxygenase (PaO) activity seems to be responsible for the stay-green genotype in the lines of pepper analyzed in this study.

Capsicum↗
PubMed2004

Optimization and evolution of light harvesting in photosynthesis: the role of antenna chlorophyll conserved between photosystem II and photosystem I.

The efficiency of oxygenic photosynthesis depends on the presence of core antenna chlorophyll closely associated with the photochemical reaction centers of both photosystem II (PSII) and photosystem I (PSI). Although the number and overall arrangement of these chlorophylls in PSII and PSI differ, structural comparison reveals a cluster of 26 conserved chlorophylls in nearly identical positions and orientations. To explore the role of these conserved chlorophylls within PSII and PSI we studied the influence of their orientation on the efficiency of photochemistry in computer simulations. We found that the native orientations of the conserved chlorophylls were not optimal for light harvesting in either photosystem. However, PSII and PSI each contain two highly orientationally optimized antenna chlorophylls, located close to their respective reaction centers, in positions unique to each photosystem. In both photosystems the orientation of these optimized bridging chlorophylls had a much larger impact on photochemical efficiency than the orientation of any of the conserved chlorophylls. The differential optimization of antenna chlorophyll is discussed in the context of competing selection pressures for the evolution of light harvesting in photosynthesis.

Chlorophyll↗
PubMed1983

Changes in the lateral distribution of the light-harvesting chlorophyll-a/b--protein complex induced by its phosphorylation.

The effect of protein phosphorylation on the distribution of chlorophyll-protein complexes between appressed and non-appressed thylakoid regions of spinach chloroplasts has been investigated. Stroma lamellae vesicles and inside-out vesicles, representative of non-appressed and appressed thylakoids, respectively, were isolated from thylakoid membranes before and after phosphorylation. The fractions were analyzed with respect to the yield of vesicles, incorporation of [32P]phosphate into the light-harvesting chlorophyll-a/b--protein complex, chlorophyll composition, and the relative content of the main chlorophyll-protein complexes. The yield of inside-out vesicles from phosphorylated thylakoids was 20% lower than that from control thylakoids, indicating a partial destacking. The specific incorporation of [32P]phosphate into the light-harvesting chlorophyll-a/b--protein complex was at least four times higher in stroma lamellae vesicles than in inside-out vesicles. The proportion of the light-harvesting chlorophyll-a/b--protein complex in stroma lamellae vesicles increased from 13% to 21% of their total chlorophyll after phosphorylation of the thylakoids. There was also a corresponding increase in the level of chlorophyll b. These observations strongly suggest that phosphorylated light-harvesting complexes migrate from appressed thylakoids rich in photosystem 2 to non-appressed thylakoids rich in photosystem 1. In contrast, there was no evidence for a lateral migration of the chlorophyll-a--protein complex of photosystem 2 after phosphorylation. Our results indicate that a lateral migration of phosphorylated light-harvesting complexes in combination with a lateral separation of photosystem 1 and 2 to the different thylakoid regions, is a basis for the regulation of excitation energy between the two photosystems.

Chemical Phenomena↗
PubMed1994

Heterogenous lipid distribution among chlorophyll-binding proteins of photosystem II in maize mesophyll chloroplasts.

Photosystem II membrane fractions from dark-adapted mesophyll chloroplasts of maize were solubilized in different concentrations of dodecyl beta-D-maltoside. Chlorophyll-binding proteins from photosystem II were isolated either by ultracentrifugation on a sucrose gradient, or by flat bed isoelectric focusing and identified by gel electrophoresis analysis for their polypeptide composition. Lipid and fatty acid compositions were determined in complexes prepared by both methods and also in purified light-harvesting complex II, in minor chlorophyll a/b binding complexes 29, 26, 24, in photosystem II antennae (chlorophyll-protein complexes 43, 47) and in the photosystem II reaction centers chlorophyll-protein complexes. Comparative analysis of the results suggests that a true heterogeneity exists in the lipid class distribution among the different chlorophyll-protein complexes in this region of the photosynthetic membrane. Photosystem II core fractions prepared either by ultra-centrifugation on a sucrose gradient or by isoelectric focusing were found significantly enriched in monogalactosyldiacylglycerol; fractionation of the photosystem II core in its components showed that it was the chlorophyll-protein complexes 43 and 47 which were mainly responsible for this enrichment. One of them, the chlorophyll-protein complex 47, was found containing monogalactosyldiacylglycerol and having a very high level of saturated fatty acids. The minor chlorophyll a/b binding linkers (chlorophyll-protein complexes 24, 26 and 29) retain a largely higher amount of lipids than all other complexes and especially of highly unsaturated galactolipids. Concerning the main light-harvesting antenna (LHCII), it is demonstrated that phosphatidylglycerol is strongly linked to the complex if it cannot be detached at high detergent concentration, while many galactolipids (which nevertheless represent the major lipid classes) are lost. This main light-harvesting complex has been fractionated into several families by isoelectric focusing showing a marked difference in lipid and polypeptide composition. A spectacular increase in the phosphatidylglycerol content was observed in the fraction migrating near the anode and enriched in a 26-kDa polypeptide; but this result is difficult to interpret in physiological terms as it was shown that phosphatidylglycerol alone, because of its negative charge, also migrates toward the anode in isoelectric focusing.

Chemical Fractionation↗
PubMed1992

Inherent limitations of nondestructive chlorophyll meters: a comparison of two types of meters.

Two types of nondestructive chlorophyll meters were compared with a standard, destructive chlorophyll measurement technique. The nondestructive chlorophyll meters were 1) a custom built, single-wavelength meter, and 2) the recently introduced, dual-wavelengh, chlorophyll meter from Minolta (model SPAD-502). Data from both meters were closely correlated with destructive measurements of chlorophyll (r2 = 0.90 and 0.93; respectively) for leaves with chlorophyll concentrations ranging from 100 to 600 mg m-2, but both meters consistently overestimated chlorophyll outside this range. Although the dual-wavelength meter was slightly more accurate than the single-wavelength meter (higher r2), the light-scattering properties of leaf cells and the nonhomogeneous distribution of chlorophyll in leaves appear to limit the ability of all meters to estimate in vivo chlorophyll concentration.

Chlorophyll↗
PubMed2001

Seasonal changes of chlorophyll content in field-grown rice crops and their relationships with growth.

Field experiments were conducted on the experimental farm of the Taiwan Agricultural Research Institute (TARI) to examine seasonal changes in the amounts of chlorophylls in leaves and whole plants of rice (Oryza sativa L. cv. Tainung 67) grown in the first and the second crop seasons in 1998. Chlorophyll (Chl) differences between two crops and their relationships with growth were also investigated. The differences in climate conditions between the two crop seasons were quite phenomenal and led to different rates of plant growth and amounts of chlorophyll produced during the growth periods. Seasonal changes in Chla, Chlb, and total Chl were curvilinear in style, with Chla making up the major portion of total chlorophyll. Young plants of rice began with lower levels of chlorophyll, which increased as the plants developed, and decreased as the plants aged. A significant increase in chlorophyll occurred in the early stage of the second crop compared to that of the first crop, and the difference was maintained throughout the growing season. When the unit time transformation technique was used to exclude the difference in growth rate, the curves of the chlorophylls (Chla, Chlb, and total ChI) were similar in the two crops, but plants grown in the second crop season had higher levels of chlorophylls at the same time unit scale. Generally, the ratio of Chla to Chlb (Chla/Chlb) decreased after transplanting, indicating a significant reduction (p < 0.01) in the green-to-yellow pigment relationship. Plants grown in the first crop had higher Chla/Chlb ratios than those grown in the second crop, especially in leaf blades. Good agreement was found between growth traits and the respective total Chl cotent from regression analyses, and these growth traits were highly correlated with total Chl (R2 > 0.8). However, rice plants grown in the first crop showed a higher levels of plant growth and leaf area at the same chlorophyll level than those grown in the second crop. These results suggest that rice plants grown in the first crop may exhibit better growth and production than those grown in the second crop under normal growing conditions.

Chlorophyll↗
PubMed1992

[Chlorophyll synthesis in cotyledons after gamma ray irradiation of black pine seeds].

The radiosensitivity of the greening system of Pinus nigra Arn. cotyledons has been studied in this paper. An exponential relation exists between the effect and dose for chlorophyll synthesis in the dark. Chlorophyll synthesis in the light roughly parallels that of chlorophyll synthesis in the dark. The restoration of chlorophyll was observed both in the light and in the dark. A stimulative effect of low doses of gamma radiation on chlorophyll synthesis was noticed. The radiosensitivity of chlorophyll a and chlorophyll b synthesis varied with the experimental conditions, suggesting that chlorophyll b synthesis might occur independently of chlorophyll a synthesis.

Chlorophyll↗
PubMed1997

[Simultaneous determination of carotenoids and chlorophylls in algae by high performance liquid chromatography].

An isocratic reversed-phase HPLC method for the simultaneous determination of carotenoids and chlorophylls in algae is presented. Both carotenoids and chlorophylls were separated by using a C18 column and a mobile phase consisting of dichloromethane/acetonitrile/methanol/water (22.5:9.5:67.5:0.5). The flow rate was 1.0mL/min. These pigments were detected by a UV-VIS absorbance detector set at 450nm. The average recoveries of these pigments by standard addition method were 99.1% for lutein, 98.5% for alpha-carotene, 99.4% for beta-carotene, 100.6% for chlorophyll a and 99.9% for chlorophyll b. The relative standard deviations of these pigments were 2.4% for lutein, 5.6% for alpha-carotene, 6.0% for beta-carotene, 4.1% for chlorophyll a and 4.0% for chlorophyll b. The calibration curves for these pigments gave good linearity over a wide range of 0-50mg/L (r = 0.9992-0.9999). The retention times were 3.0 min for lutein, 4.7 min for chlorophyll b, 6.3 min for chlorophyll a, 14.1 min for alpha-carotene, and 14.7 min for beta-carotene. Using this method, carotenoids and chlorophylls were determined in Spirulina platensis, Chlorella vulgaris and Haematococcus lacustris. Chlorella vulgaris and Haematococcus lacustris samples were ground in a B. Braun homogenizer. Spirulina platensis sample was smashed by supersonic wave. Acetone was used as extractant.

Carotenoids↗
PubMed1986

Regulation of chloroplast-encoded chlorophyll-binding protein translation during higher plant chloroplast biogenesis.

Etioplasts of 5-day-old dark-grown barley seedlings synthesize most of the soluble and membrane proteins found in chloroplasts of illuminated plants. Prominent among these proteins are the large subunit of ribulose bisphosphate carboxylase and the alpha- and beta-subunits of the chloroplast ATPase. However, etioplasts do not synthesize four chloroplast-encoded proteins which are major constituents of the chloroplast thylakoid membrane: two chlorophyll apoproteins of photosystem I (68 and 65 kDa) and two chlorophyll apoproteins of photosystem II (47 and 43 kDa). Pulse-labeling experiments show that the lack of radiolabel accumulation in the chlorophyll apoproteins in etioplasts is due to inhibition of synthesis rather than apoprotein instability. Illumination of 5-day-old dark-grown barley selectively induces synthesis of the plastid-encoded chlorophyll apoproteins and proteins of 32, 23, and 21 kDa. Synthesis of the chlorophyll apoproteins was significant in plants illuminated for 15 min and was near maximum by 1 h. The induction of photosystem I chlorophyll apoprotein synthesis was not accompanied by an increase in mRNA for these proteins. These results demonstrate that the synthesis of the plastid-encoded photosystem I chlorophyll apoproteins is blocked at the translational level in dark-grown barley. Translation of the chlorophyll apoproteins is induced rapidly by light with a time course which is similar to the light-dependent formation of chlorophyll from protochlorophyllide.

Chlorophyll↗
PubMed1995

Exploring the relationship between reflectance red edge and chlorophyll concentration in slash pine leaves.

Chlorophyll concentration is related positively to the point of maximum slope in the reflectance spectra of leaves and this point is termed the red edge. The reflectance spectra of slash pine (Pinus elliottii Engelm.) needles were measured in the field and the chlorophyll concentrations of the same needles were measured in the laboratory. The measurement errors for red edge and chlorophyll concentration were determined to be 2.2 nm (3% of mean) and 0.35 mg g(-1) (19% of mean), respectively. The red edge-chlorophyll concentration relationship was strong (r(2) = 0.82, n = 152). A red edge-chlorophyll concentration relationship for n = 100 was used with red edge measurements to estimate chlorophyll concentration with an rms error of 0.31 mg g(-1) (17% of mean, n = 52). The entire red edge-chlorophyll concentration relationship for n = 152 was also used with red edge measurements to estimate the chlorophyll concentration of samples from an earlier experiment with an rms error of 0.47 mg g(-1) (30% of mean, n = 38). We conclude that measures of red edge can be used to estimate the chlorophyll concentration of detached needles in the field with an accuracy similar to that obtained by conventional laboratory measurements.

Journal Article↗
PubMed1976

The Light-harvesting Chlorophyll a/b-Protein Complex of Chlamydomonas reinhardii.

The molecular organization of chlorophyll in Chlamydomonas reinhardii has been shown to be essentially similar to that in higher plants. Some 50% of the chlorophyll in Chlamydomonas reinhardii chloroplast membranes has been shown to be located in a chlorophyll a/b-protein complex. The complex was isolated in a homogeneous form by hydroxylapatite chromatography of sodium dodecyl sulfate extracts of the chloroplast membranes. Its absorption spectrum exhibits two maxima in the red region at 670 and 652 nm due to the presence of equimolar quantities of chlorophylls a and b in the complex. Preparations of the chlorophyll-protein also contain some of each of the carotenoids observed in the intact chloroplast membrane, but not in the same proportions. The native complex (S value = 2.3S) exhibits a molecular weight of 28,000 +/- 2,000 on calibrated sodium dodecyl sulfate-polyacrylamide gel electrophoresis. However, on the basis of its amino acid composition and other data a more probable molecular weight of about 35,000 was calculated. Each 35,000 dalton unit contains three chlorophyll a and three chlorophyll b molecules, and on the average one carotenoid molecule conjugated with probably a single polypeptide of 29,000 daltons. Comparison of spectral and biochemical characteristics demonstrates that this algal chlorophyll-protein is homologous to the previously described major light-harvesting chlorophyll a/b-protein of higher plants. It is anticipated that the Chlamydomonas complex functions solely in a light-harvesting capacity in analogy to the function determined for the higher plant component.

Journal Article↗
PubMed1977

Chlorophyll destruction by the bisulfite-oxygen system.

Destruction of chlorophyll, as determined by the loss in absorbance at 665 nm, occurred in two in vitro systems in the presence of bisulfite in 76% ethanol. The first system required light and O(2) in addition to bisulfite and exhibited an optimum pH of 4. Chlorophyll functioned as a photosensitizer and there was little chlorophyll destruction occurring above pH 5. With 286 mueinsteins m(-2) irradiation, approximately 80% of the chlorophyll was destroyed in three minutes. In the second system, chlorophyll destruction in the presence of bisulfite occurred in the dark and required Mn(2+), O(2), and glycine. Destruction of chlorophyll in this system was much more rapid than in the light system with approximately 70% destruction occurring in two seconds. In both systems, chlorophyll destruction was linked to bisulfite oxidation. The free radical scavengers hydroquinone, butylated hydroxytoluene, 1,2-dihydroxybenzene-3,5-disulfonic acid, and alpha-tocopherol were effective in inhibiting the destruction of chlorophyll in both systems. The singlet O(2) scavengers, 2,5-dimethylfuran and 1,3-diphenylisobenzofuran, were ineffective inhibitors and beta-carotene only slightly effective when tested in the light system. The evidence suggests that in these two systems chlorophyll was destroyed by free radicals, probably superoxide radical, which was produced during the aerobic oxidation of bisulfite.

Journal Article↗
PubMed1980

Nutritional Regulation of Organelle Biogenesis in Euglena: REPRESSION OF CHLOROPHYLL AND NADP-GLYCERALDEHYDE-3-PHOSPHATE DEHYDROGENASE SYNTHESIS.

Nitrogen deficiency and the presence of specific organic carbon sources prevent chloroplast development in Euglena. In exponentially growing cultures, chlorophyll levels were low and independent of the nitrogen content of the growth medium. Chlorophyll levels increased in stationary phase and the amount of chlorophyll formed was proportional to the initial nitrogen content of the growth medium; the greater the concentration of nitrogen, the greater the amount of chlorophyll synthesized during stationary phase. Washing experiments demonstrated that the major nutritional factor inhibiting chlorophyll synthesis in stationary phase cultures grown on medium containing a high carbon to nitrogen ratio was the absence of nitrogen rather than the presence of utilizable organic carbon.The light-induced synthesis of chlorophyll and of NADP-glyceraldehyde-3-phosphate dehydrogenase was inhibited when acetate or ethanol was added at the time of exposure of dark-grown resting cells to light. Malate addition, however, stimulated chlorophyll and enzyme synthesis. Both cell number and total cell protein increased after ethanol, acetate, or malate addition, indicating that the resting cells were not nitrogen-deficient. Ethanol and acetate specifically repress light-induced chlorophyll synthesis. NADP-glyceraldehyde-3-phosphate dehydrogenase synthesis was inhibited at a time, the first 24 hours of light exposure, when chlorophyll synthesis was unaffected by carbon addition.

Journal Article↗
PubMed1984

Isolation and Characterization of a Light-Harvesting Chlorophyll a/b Protein Complex Associated with Photosystem I.

A chlorophyll a/b protein complex has been isolated from a resolved native photosystem I complex by mildly dissociating sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The chlorophyll a/b protein contains a single polypeptide of molecular weight 20 kilodaltons, and has a chlorophyll a/b ratio of 3.5 to 4.0. The visible absorbance spectrum of the chlorophyll a/b protein complex showed a maximum at 667 nanometers in the red region and a 77 K fluorescence emission maximum at 681 nanometers. Alternatively, by treatment of the native photosystem I complex with lithium dodecyl sulfate and Triton, the chlorophyll a/b protein complex could be isolated by chromatography on Sephadex G-75. Immunological assays using antibodies to the P(700)-chlorophyll a-protein and the photosystem II light-harvesting chlorophyll a/b protein show no cross-reaction between the photosystem I chlorophyll a/b protein and the other two chlorophyll-containing protein complexes.

Journal Article↗
PubMed1989

A new form of chlorophyll C involved in light-harvesting.

A new form of chlorophyll c has been isolated from the pyrmnesiophyte Pavlova gyrans Butcher. This pigment is spectrally similar to chlorophyll c(2), but all the absorption maxima (454, 583, and 630 nm in diethyl ether) are shifted 4 to 6 nanometers to longer wavelengths. The new pigment can be separated from other chlorophyll c-type pigments by reversed-phase high performance liquid chromatography and thin layer chromatography. Both chlorophylls c(1) and c(2) are found with the new chlorophyll c pigment in P. gyrans, and it has also been detected in the chrysophyte Synura petersenii Korsh. The light-harvesting function of the new chlorophyll c pigment is indicated by its presence along with chlorophyll c(1) and c(2) in a light-harvesting pigment-protein complex isolated from P. gyrans in which chlorophyll c pigments efficiently transfer absorbed light energy to chlorophyll a.

Journal Article↗
PubMed1990

Light-harvesting proteins of diatoms: their relationship to the chlorophyll a/b binding proteins of higher plants and their mode of transport into plastids.

We have cloned and characterized members of a gene family encoding polypeptide constituents of the fucoxanthin, chlorophyll a/c protein complex, a light-harvesting complex associated with photosystem II of diatoms and brown algae. Three cDNA clones encoding proteins associated with this complex in the diatom Phaeodactylum tricornutum have been isolated. As deduced from the nucleotide sequences, these light-harvesting proteins show homology to the chlorophyll a/b binding polypeptides of higher plants. Specifically, the N-terminal regions of the fucoxanthin, chlorophyll a/c-binding proteins are homologous to the chlorophyll a/b binding proteins in both the third membrane-spanning domain and the stroma-exposed region between membrane-spanning domains 2 and 3. Like the chlorophyll a/b-binding proteins, the mature fucoxanthin, chlorophyll a/c polypeptides have three hydrophobic alpha-helical domains which could span the membrane bilayer. The similarities between the two light-harvesting proteins might reflect the fact that both bind chlorophyll molecules and/or might be important for maintaining certain structural features of the complex. There is little similarity between the N-terminal sequences of the primary translation products of the fucoxanthin, chlorophyll a/c proteins and any transit sequences that have been characterized. Instead, the N-terminal sequences have features resembling those of signal sequences. Thus either transit peptides used in P. tricornutum show little resemblance to those of higher plants and green algae or the nuclear-encoded plastid proteins enter the organelle via a mechanism different from that used in higher plants.

Amino Acid Sequence↗
PubMed2005

Hydrogen, carbon and nitrogen isotopic fractionations during chlorophyll biosynthesis in C3 higher plants.

We determined hydrogen, carbon and nitrogen isotopic compositions of chlorophylls a and b isolated from leaves of five C3 higher plant species (Benthamidia japonica, Prunus japonica, Acer carpinifolium, Acer argutum and Querus mongloica), and hydrogen and carbon isotopic compositions of phytol and chlorophyllides in the chlorophylls to understand isotopic fractionations associated with chlorophyll biosynthesis in these species. Chlorophylls are depleted in D relative to ambient water by approximately 189 per thousand and enriched in (13)C relative to bulk tissue by approximately 1.6 per thousand. These data can be explained by the contribution of isotopic fractionations during phytol and chlorophyllide biosyntheses. Phytol is more depleted in both D (by approximately 308 per thousand) and (13)C (by approximately 4.3 per thousand), while chlorophyllides are less depleted in D (by approximately 44 per thousand) and enriched in (13)C (by approximately 4.8 per thousand). Such inhomogeneous distribution of isotopes in chlorophylls suggests that (1) the phytol in chlorophylls reflects strong D- and (13)C-depletions due to the isotopic fractionations during the methylerythritol phosphate pathway followed by hydrogenation, and (2) the chlorophyllides reflect D- and (13)C-enrichments in tricarboxylic acid cycle. On the other hand, chlorophylls are slightly ( approximately 1.2 per thousand) depleted in (15)N relative to the bulk tissue, indicating that net isotopic fractionation of nitrogen during chlorophyll biosynthesis is small compared with those of hydrogen and carbon.

Carbon Isotopes↗
PubMed2000

Suspended chlorophyll in the River Nene, a small nutrient-rich river in eastern England: long-term and spatial trends.

The distribution of suspended algae was investigated in a 69-km length of a small lowland river in the UK, the Nene, using chlorophyll as a measure of biomass. Variations in chlorophyll data collected between 1975 and 1996 by water management organisations at a downstream site (km 91.7) were evaluated against a range of physical and chemical variables. Interpretation was aided by additional sampling at eight sites on the main river (including km 91.7) and three tributaries between 1994 and 1996. Significant inter-year variation was evident in all data and was most pronounced in discharge. The latter half of the 22-year period had significantly higher temperature and light and significantly lower ammonia concentrations. Discharge, temperature and light were significant predictors of chlorophyll concentration, particularly between January and June, and spring chlorophyll maxima ranged from 106 to 276 microg l(-1). Summer chlorophyll concentrations were generally low relative to spring peaks. Some summers, however, had very low chlorophyll concentrations (average < 10 microg l(-1)) which were independent of the controlling factors at other times and inter-year variation in submerged macrophyte abundance is proposed as a causal factor for their occurrence. Spring chlorophyll peaks occurred earlier and had smaller amplitude at downstream sites compared to those further upstream. Average spring chlorophyll concentration (April-June) increased significantly between km 22.4 and 43.9, thereafter remaining high to km 91.7. Spatial trends were attributed to changes in channel morphology, retention time and longitudinal variations in velocity and temperature.

Biomass↗