Studies on a barley mutant lacking chlorophyll b II. Fluorescence properties of isolated chloroplasts

Boardman, N.K.; Thorne, S.W.

doi:10.1016/0005-2728(68)90086-8

Cited by 73 publications

(15 citation statements)

References 21 publications

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“…Weak white light was obtained by reflection from a single white fluorescent lamp, the incident intensity at leaf level being 50 erg cm-2sec'1 or between 2 and 3 ft-c on the light meter. Moderate white light of intensity 2 (8). The bandwidths of the excitation and emission monochromators were ± 1.5 nm and + 1.0 nm, respectively.…”

Section: Methodsmentioning

confidence: 99%

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Formation of Chlorophyll b, and the Fluorescence Properties and Photochemical Activities of Isolated Plastids from Greening Pea Seedlings

Thorne

Boardman

1971

Plant Physiol.

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Chlorophyll b was first detectable after 10 minutes of illumination of etiolated pea seedlings (Pisum sativum L. var Greenfeast) with continuous white light. The chlorophyll a/b ratio decreased from 300 at 10 minutes to 15 after 1 hour. There was little change in the chlorophyll a/b ratio between 1 and 2 hours, and it declined to 3 between 2 and 5 hours of illumination. In red light, the time courses of total chlorophyll synthesis and chlorophyll a/b ratio were similar to those in white light for the first 5 hours of illumination. But with increasing time of illumination with red light, there was an increase in the chlorophyll a/b ratio to 7 after 30 hours. Illumination with white light of very low intensity also gave high chlorophyll a/b ratios. Seedlings which had been illuminated for varying periods and then returned to darkness always showed an increase in chlorophyll a/b ratio during the dark period. It is concluded that the synthesis of chlorophyll b is controlled by light.The onset of the transfer of excitation energy from carotenoids to chlorophyll a correlated with the appearance of chlorophyll b. The detection of chlorophyll b and the onset of energy transfer from carotenoids to chlorophyll a preceded by several hours the appearance of Hill activity in the isolated pea plastids. The detection of the large fluorescence emission band at 735 nm at 77 K also preceded the observation of Hill activity, but it correlated with the phase of rapid chlorophyll synthesis. There was a good correlation between Hill activity and the formation of grana. The fluorescence kinetics which are characteristic of mature chloroplasts appeared considerably later than grana or the observation of Hill activity.It is concluded that the formation of photosynthetic membranes and the assembly of the photosystems is not a single step process, at least in the initial stages of chloroplast development from the etioplast.In angiosperm seedlings the synthesis of chlorophyll and the formation of photosynthetically active membranes is controlled by light. Following the initial photoconversion of protochlorophyllide to chlorophyllide a there is a lag phase of 1 to 3 hr, depending on the age and species of plant, before additional chlorophyll is synthesized. The lag phase in continuous light is controlled to some degree by phytochrome, since it can be eliminated by giving dark-grown seedlings a short exposure to red light followed by 3 to 5 hr of darkness. Continuous irradiation following the dark period causes an immediate rapid formation of chlorophyll. The effect of red light can be partly reversed by far red light (26,29,36).Phytylation of chlorophyllide a occurs over a period of 30 to 40 min after the initial photoconversion of protochlorophyllide, and the esterification does not require additional light (5, 37). The appearance of chlorophyll b has been correlated with the end of the lag phase and the synthesis of additional chlorophyll a (35). Recently, Rudoi et al. (30) have reported that chlorophyll b is detectable within a ...

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Section: Methodsmentioning

confidence: 99%

“…The bandwidths of the excitation and emission monochromators were ± 1.5 nm and + 1.0 nm, respectively. Fluorescence quantum efficiencies were measured by an extension of the relative method (8). Fluorescence kinetics were measured as described earlier (8).…”

Section: Methodsmentioning

confidence: 99%

Formation of Chlorophyll b, and the Fluorescence Properties and Photochemical Activities of Isolated Plastids from Greening Pea Seedlings

Thorne

Boardman

1971

Plant Physiol.

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“…ment was diluted 100-fold into ethanol (absorbance <0.05 at 660 nm) and was analyzed by narrow band fluorescence spectroscopy at 77 K. At this temperature, the excitation and emission spectra are considerably sharpened and enhanced, whilst ethanol provides a clear, frozen, transparent medium. Also, as has been shown previously (6), advantageous shifts in relative peak positions of both chlorophylls and pheophytins occur at 77 K, allowing greater wavelength separation of the mixed pigment peak positions and giving up to a 10-fold increase in both sensitivity and selectivity over measurements at 200C. Fluorescence emission and excitation spectra were recorded on a fluorescence spectrometer incorporating automatic corrections for photomultiplier-and monochromator responses with wavelength, and variation in the output of the light source (7,8). The fluorescence excitation band width was 1.5 nm with a fluorescence emission band width of 1 nm.…”

mentioning

confidence: 94%

Identification of chlorophyll b in extracts of prokaryotic algae by fluorescence spectroscopy.

Thorne¹,

Newcomb²,

Osmond³

1977

Proc. Natl. Acad. Sci. U.S.A.

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Solvent extracts of three different prokaryotic algae from three species of didemnid ascidians contained pigments identified, on the basis of their fluorescence excitation (E) and fluorescence emission (F) spectral maxima (measured in nm) at 77 K, as chlorophyll a (E 449, F 678) and chlorophyll b (E 478, F 658). The release of algae on cutting or freezing Diplosoma virens was accompanied by a strong unidentified acid that converted these pigments to pheophytins. This unexpected finding provided further confirmation of the identity of the chlorophylls on the basis of the fluorescence spectra at 77 K of pheophytin a (E 415, F 669) and pheophytin b (E 439, F 655). There was no evidence for the presence of the fluorescent bilin pigments found in other prokaryotic blue-green algae. Chlorophyll a/b ratios ranged from 2.6 to 12.0 in algae from different ascidians. The photosynthetic membranes were not organized into appressed thylakoids or grana in the algae from any of the three species of ascidians. The relationship between these observations and those in higher eukaryotic organisms is discussed.Several species of colonial ascidians in the family Didemnidae (Phylum Chordata, Subphylum Urochordata) from the Great Barrier Reef of northeastern Australia harbor bright green, unicellular algae in their cloacal cavities. Earlier studies of these algae showed that they are prokaryotic, with an ultrastructure resembling that of blue-green algae, but that they apparently lack the phycobilin pigments and the phycobilosomes characteristic of the blue-green algae (1). Similar prokaryotic algae have been reported growing on the surface of an unidentified didemnid ascidian from Baja California, and the presence of chlorophylls a and b in these algae was provisionally established on the basis of chromatography and room temperature absorbance spectra (2,3 (Hartmeyer), Trididemnum Cyclops (Michaelsen), and juvenile colonies of Didemnum ternatanum (Gottschaldt) were collected at low tide from coral rocks immediately behind the reef front. Larger, older colonies of D. ternatanum were found attached to branches of staghorn coral in deeper water along the front edge of the reef. The specimens collected in July were identified at the Heron Island Research Station laboratory by Patricia Kott Mather. Samples were embedded as previously described (4) for later electron microscopic study.Differences were noted in the ease with which the algae are removed from their ascidian hosts. Those from Diplosona mrens were released readily by applying pressure to the ascidian colony after it had been cut in two. The algae from this ascidian were either expressed into cold, filtered sea water, or into cold 0.1 M Tris.HCl buffer at pH 8.3, and then sedimented by centrifugation. Algae were much more difficult to extract from the other two ascidians, and consequently were isolated in relatively small quantities from these species. In Didemnum ternatanum their release is accompanied by the breakage of many of the algal cells and by embedment of the ...

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“…Hill reaction measurements on isolated chloroplasts showed that the mutant chloroplasts were more active per mg of total chlorophyll if assayed at saturating light intensities, but less active at low light intensities (6). The mutant chloroplasts were less fluorescent (7), and their molar ratio of total chlorophyll to cytochrome b6 plus cytochrome 559 was only about one-half of the corresponding ratio of normal chloroplasts (4).…”

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confidence: 99%

Photosynthetic Studies on a Pea-mutant Deficient in Chlorophyll

1969

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Abstract. A chlorophyll-deficient mutant of pea (Pisum sativum) was found as a spontaneous mutation of the variety Greenfeast. Total chlorophyll of the mutant leaves was about one-half that of normal pea leaves per mg dry weight, and the ratio of chl a:chl b ranged from 10 to 18, compared with 3 for normal pea. In each generation the mutant plants gave rise to normal and mutant plants and lethal plants with yellow leaves.For a normal pea plant, CO2 uptake was saturated at about 60,000 lux, whereas with mutant leaves, the rate of CO2 uptake was still increasing at 113,000 lux. At 113,000 lux the mutant and normal leaves showed similar rates of CO2 fixation per unit area of leaf surface, but on a chlorophyll basis the mutant leaves were twice as active. Hill reaction measurements on isolated chloroplasts also showed that the mutant chloroplasts werc saturated at higher intensities than the normal, and that the activity of the mutant was at least double that of the normal on a chlorophyll basis.It is suggested that the photosynthetic units of the mutant chloroplasts contain about half the number of chlorophyll molecules as compared to the normal photosynthetic units.Electron microscopy of leaf sections of normal and mutant leaves showed that the mutant chloropla,sts oontain fewer lamellae per chloroplast and fewer lamellae per granum. The lethal chloroplasts, which were virtually devoid of chlorophyll, were characterized by an absence of grana.

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Studies on a barley mutant lacking chlorophyll b II. Fluorescence properties of isolated chloroplasts

Cited by 73 publications

References 21 publications

Formation of Chlorophyll b, and the Fluorescence Properties and Photochemical Activities of Isolated Plastids from Greening Pea Seedlings

Formation of Chlorophyll b, and the Fluorescence Properties and Photochemical Activities of Isolated Plastids from Greening Pea Seedlings

Identification of chlorophyll b in extracts of prokaryotic algae by fluorescence spectroscopy.

Photosynthetic Studies on a Pea-mutant Deficient in Chlorophyll

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