Kinetics of the dichroic reorientation of phytochrome during photoconversion inMougeotia

Kraml, Manfred; Enders, Margit M.; Bürkel, Nobert

doi:10.1007/bf00982915

Cited by 20 publications

(8 citation statements)

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“…This response is also wavelength dependent, with 690 nm being inactive, and repeated irradiation being necessary to obtain a response (Table 3b). A similar result was reported for red millisecond-flash irradiation (Kraml et al, 1984).…”

Section: Resultssupporting

confidence: 89%

INDUCTION OF CHLOROPLAST MOVEMENT IN THE ALGA Mougeotia BY POLARIZED NANOSECOND DYE‐LASER PULSES*^†

Scheuerlein

Braslavsky

1987

Photochem & Photobiology

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Chloroplast movement of white‐light treated alga Mougeotia was induced by 15‐ns dye‐laser pulses (620‐690 nm). A single pulse, polarized perpendicular to the cell axis, does not induce a significant response, although full response can be obtained when the same fluence is applied during a 30‐s irradiation. However, for 620 and 660 nm perpendicularly polarized flash irradiation results in a significant response, if the total fluence is given by 2 consecutive flashes with 2‐s dark interval (double‐flash effect), and full response can be obtained by poly‐flash induction. Flashes of 690 nm in no case induce a response. Similar to the case of lettuce‐seed germination (Scheuerlein and Braslavsky, 1985), the establishment of a photochromic system between Pr and the very early intermediates (= lumi‐R) during the 15‐ns laser pulse can explain the results. At 690 nm, the photochromic system is shifted more extensively to Pr than at shorter wavelengths; thus, Pfr formation is strongly diminished. At shorter wavelengths (620 and 660 nm) the inhibition of Pfr formation by the existence of this photochromic system is smaller. The results are compatible with parallel dipole moments of the chromophores in Pr and in the first intermediates. A smaller but still significant response is obtained for repeated pulses of 660‐nm light, polarized parallel to the cell axis. These results are explained by a gradient in light sensitivity around the cell axis (induced by the white‐light pretreatment) and an increasing Plr concentration, established around the cell axis, as a function of the number of pulses.

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Section: Resultssupporting

confidence: 89%

INDUCTION OF CHLOROPLAST MOVEMENT IN THE ALGA Mougeotia BY POLARIZED NANOSECOND DYE‐LASER PULSES*^†

Scheuerlein

Braslavsky

1987

Photochem & Photobiology

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“…The low energy, phytochrome-mediated chloroplast response and the response characterized here lead to the same kind of chloroplast movement (to face position), but it seems that they are mediated by different transduction chains. This conclusion is consistent with the results showing that this type of chloroplast response is strongly dependent upon irradiance in the FR (low Pfr/Pto, ratio) (1 1, 18) while in the low energy phytochrome-mediated response it occurs in the R (high Pfr/Ptow ratio) (9,10).…”

supporting

confidence: 92%

“…The data do not conform to the known properties of the low energy phytochrome effects that are induced by small total light fluences (low irradiance times short time) and that show full or nearly full reversibility during successive exposure to R and FR (9,10). In the case of low energy phytochrome-mediated chloroplast response in Mougeotia, flash durations of a few milliseconds are enough to induce chloroplast orientation (10 and GL on leaflet movement in Albizzia (15,16) and concerning the generation of a bioelectrical field potential of the soybean hypocotyl (17).…”

contrasting

confidence: 67%

Action Spectrum for Interaction between Visible and Far-Red Light on Face Chloroplast Orientation in Mougeotia

Lechowski¹,

Białçzyk²

1988

Plant Physiol.

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The orientation of chloroplasts from profile to face position in Mougeotia can be controlled in two ways: by a typical phytochrome-mediated system or by continuous, simultaneous irradiation with far-red and visible light. In experiments with dichromatic irradiation of Mougeotia, the light conditions applied prevented the formation of a far-red-absorbing form of phytochrome gradient in the cell. An unpolarized background of farred light and linearly polarized monochromatic light of different wavelengths and vibrating parallel to the cell axis, if given by themselves, were completely ineffective in producing any changes in chloroplast orientation. Given together, however, changes in chloroplast orientation were induced. The action spectrum for this interaction between constant far-red and variable visible light was maximal at 620 nanometers. The chloroplast response in these dichromatic light conditions required a prolonged duration of exposure to simultaneous continuous irradiation of high fluence energy. The vibrating plane of linearly polarized 620 nanometer light had no significant influence on interaction with far-red light in chloroplast movement. The results obtained are different from the typical low energy phytochrome-mediated chloroplast orientation. This new type of chloroplast photoresponse might be mediated by an unknown sensory pigment.Light-oriented chloroplast movement in Mougeotia has been shown to be controlled by R2 and BL. The low-fluence-rate chloroplast orientation (profile to face position) is most effectively induced by R (14), with phytochrome being involved (for detailed information, see Refs.

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“…Intuitively the slowest component in the conversion of P, to Pfr involves the largest conformational change of the chromophore and protein. It is already known from physiological experiments (Kraml et al, 1984) and in vitro experiments (Sundqvist and Bjorn, 1983) that the absorption dichroism of P changes upon photo-transformation. It seems likely that these large three dimensional rearrangements take place as Pf, is formed.…”

Section: Resultsmentioning

confidence: 99%

KINETICS OF P_fr APPEARANCE IN Amaranthus caudatus‡

Kendrick

Kome

Jaspers

1985

Photochem & Photobiology

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Abstract— The kinetics of the far‐red absorbing form of phytochrome (Pfr) appearance from intermediates in the pathway from the red absorbing form of phytochrome (Pr) to Pfr that accumulate under high fluence rate white light have been investigated in 3‐day old dark grown Amaranthus caudatus seedlings. The appearance of P(r after a 5 s white light pulse was measured over the temperature range ‐8 to 25°C in samples flushed with O2 or N2. Over the whole temperature range under anaerobic conditions the kinetics of the slowest component of Pfr appearance are faster than in the presence of O2. Arrhenius plots are linear over this temperature range and indicate the activation energy for the slowest component of Pfr appearance is 44.05 ± 1.97 kJ mol−1 for O2 and 53.69 ± 4.86 kJ mol−1 for N2.

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Kinetics of the dichroic reorientation of phytochrome during photoconversion inMougeotia

Cited by 20 publications

References 20 publications

INDUCTION OF CHLOROPLAST MOVEMENT IN THE ALGA Mougeotia BY POLARIZED NANOSECOND DYE‐LASER PULSES*^†

INDUCTION OF CHLOROPLAST MOVEMENT IN THE ALGA Mougeotia BY POLARIZED NANOSECOND DYE‐LASER PULSES*^†

Action Spectrum for Interaction between Visible and Far-Red Light on Face Chloroplast Orientation in Mougeotia

KINETICS OF P_fr APPEARANCE IN Amaranthus caudatus‡

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Kinetics of the dichroic reorientation of phytochrome during photoconversion inMougeotia

Cited by 20 publications

References 20 publications

INDUCTION OF CHLOROPLAST MOVEMENT IN THE ALGA Mougeotia BY POLARIZED NANOSECOND DYE‐LASER PULSES*†

INDUCTION OF CHLOROPLAST MOVEMENT IN THE ALGA Mougeotia BY POLARIZED NANOSECOND DYE‐LASER PULSES*†

Action Spectrum for Interaction between Visible and Far-Red Light on Face Chloroplast Orientation in Mougeotia

KINETICS OF Pfr APPEARANCE IN Amaranthus caudatus‡

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INDUCTION OF CHLOROPLAST MOVEMENT IN THE ALGA Mougeotia BY POLARIZED NANOSECOND DYE‐LASER PULSES*^†

INDUCTION OF CHLOROPLAST MOVEMENT IN THE ALGA Mougeotia BY POLARIZED NANOSECOND DYE‐LASER PULSES*^†

KINETICS OF P_fr APPEARANCE IN Amaranthus caudatus‡