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Plant Physiol. (1999) 119: 917-924 Chloroplast-Avoidance Response Induced by High-Fluence Blue Light in Prothallial Cells of the Fern Adiantum capillus-veneris as Analyzed by Microbeam Irradiation1
Department of Biology, Faculty of Science, Tokyo Metropolitan University, Minami Osawa 1-1, Hachioji, Tokyo 192-0397, Japan
Chloroplast movement was induced by partial cell illumination using a high-fluence blue microbeam in light-grown and dark-adapted prothallial cells of the fern Adiantum capillus-veneris. Chloroplasts inside the illuminated area moved out (high-fluence response [HFR]), whereas those outside moved toward the irradiated area (low-fluence response [LFR]), although they stopped moving when they reached the border. These results indicate that both HFR and LFR signals are generated by high-fluence blue light of the same area, and that an LFR signal can be transferred long-distance from the beam spot, although an HFR signal cannot. The lifetime of the HFR signal was calculated from the traces of chloroplast movement induced by a brief pulse from a high-fluence blue microbeam to be about 6 min. This is very short compared with that of the LFR (30-40 min; T. Kagawa, M. Wada [1994] J Plant Res 107: 389-398). These data indicate that the signal transduction pathways of the HFR and the LFR must be distinct.
Light plays an important role in the life of a plant, not only as
an energy source but also as an environmental signal. Chloroplasts migrate to sites of better illumination to optimize photosynthesis. Under weak light chloroplasts spread only over surfaces perpendicular to the direction of the light, i.e. over periclinal walls, to maximize
light absorption and generate maximum photosynthesis rates (LFR). Under
strong light chloroplasts move to the anticlinal wall to avoid the
light and minimize photodamage (HFR). In most plants these types of
chloroplast rearrangements are controlled by blue light mediated by
blue-light receptors. Although the identity of the photoreceptors is
unknown, a single photoreceptor is thought to mediate both the LFR and
the HFR, because the action spectra for both responses are very similar
(Zurzycki, 1980 In some plants, such as the fern Adiantum capillus-veneris
and the green algae Mougeotia scalaris and Mesotaenium
caldriorum, light-induced chloroplast movement is also induced by
red light and is mediated by phytochrome (Wada et al., 1993 Chloroplast relocation induced by low-fluence blue light has been
analyzed in detail in a number of plants, but the response to
high-fluence blue light has not. In the present study using dark- and
light-adapted A. capillus-veneris prothallial cells and
partial cell irradiation, we have examined how chloroplasts behave in
and out of a beam of high-fluence blue light, especially at the border
of the beam, as a first step in understanding the characteristics of
the LFR and HFR signals. We have also analyzed the difference between
HFR and LFR blue-light signals and whether red and blue light work
additively in the HFR, as is the case in the LFR.
Plant Materials and Culture Conditions
Microbeam Irradiation Prothallial cells were microbeam irradiated using an epimicrobeam irradiator (Yatsuhashi and Wada, 1990 2) was used simultaneously
in some experiments as an observation light; it was obtained by
passing light from a halogen lamp through an interference filter
(Vacuum Optics) with a transmission peak at 663.2 nm (half-band-width,
32 nm).
Analysis of Chloroplast Movement Chloroplast movement induced by microbeam irradiation was observed under IR light obtained through a filter (IR-85, Hoya) or under background red light, obtained as described above, using an IR-sensitive video camera (C2400-07ER, Hamamatsu Photonics). (A quicktime movie sequence of the light-induced chloroplast relocation shown in Figs. 1, 3, and 6 is available at http://www.nibb.ac.jp/~kagawa/ForPlantPhysiol/index.html.) Analysis of chloroplast movement was performed on a computer (Power Macintosh 7600, Apple Computer) using the public domain NIH image program (developed at the U.S. National Institutes of Health and available on the Internet at http://rsb.info.nih.gov/nih-image/). We obtained images of the observed cells at 1- or 2-min intervals, if not otherwise specified. Time courses of chloroplast movement were followed as the distance changes between a chloroplast and the center of the irradiation spot (see Figs. 2, 4, 5, 7, and 8). To estimate the duration of an avoidance response induced by brief blue-light irradiation (Figs. 7 and 8), each cell was recorded at 15-s intervals, chloroplast movement was plotted as tracks, and the times when the avoidance response began and ended were defined from this analysis. All experiments were repeated at least three times with different gametophytes.
Blue-Light-Induced Chloroplast Relocation in Dark-Adapted Prothallial Cells Chloroplast relocation was induced by a continuous blue-light microbeam with different fluence rates (3, 5, 10, and 30 W m 2) at the center of the cell surface of
dark-adapted prothallial cells in which chloroplasts were localized at
the anticlinal walls but not at the upper surface. Chloroplasts moved
toward the blue-light-irradiated area (Figs.
1 and 2)
from the cell periphery. When the chloroplasts reached the edge of the
beam spot, their behavior was different depending upon the fluence
rate. At 3 to 5 W m 2 blue light, the
chloroplasts that had located there earlier entered the beam spot and
their directionality disappeared without a break in movement, whereas
those that arrived later could not enter the irradiated area because of
space constraints. In a continuous blue-light beam of 10 or 30 W
m 2, almost all of the chloroplasts that moved
toward the irradiated area stopped at the beam edge and did not enter
the illuminated area. After the light was switched off, however, the
chloroplasts entered this area (Figs. 1 and 2, c and d).
Blue-Light-Induced Chloroplast Relocation in Light-Adapted Prothallial Cells Light-adapted prothallial cells were irradiated with continuous blue-light microbeams of different fluence rates (Figs. 3 and 4). As a control the light-adapted cells were transferred to darkness and the chloroplast behavior was observed for 1.5 h, but no chloroplast relocation could be detected (Fig. 4a). When the cells were irradiated with 3 W m 2 blue light, chloroplasts
that had located outside of the beam moved toward the irradiated area
(Fig. 4b, lines 1 and 2) and chloroplasts located at the border
moved inside (Fig. 4b, line 3). However, chloroplasts inside the beam
remained in their original position (Fig. 4b, line 4). With 5 W
m 2 blue-light treatment, inside-located
chloroplasts moved toward the beam edge for the first 10 min as if they
were avoiding the high-fluence beam, but then changed their direction
of movement back toward the center (Fig. 4c, lines 3 and 4).
Chloroplasts that were located outside moved toward the irradiated
area, but stopped if they touched other chloroplasts farther inside
(Fig. 4c, line 1). When cells were irradiated with 10 or 30 W
m 2 blue light, a typical HFR was observed.
Inside-located chloroplasts began to move toward the beam border (Figs.
3 and 4, d and e), and stopped moving when they came out of the beam.
In contrast, chloroplasts that had been located far from the beam moved
toward the irradiated area as far as they could (Fig. 4d, line 1).
After the light was switched off, the chloroplasts moved inside or
toward the inside of the beam.
Effects of Background Red-Light Illumination We next examined whether the blue-light-induced chloroplast-avoidance response was affected by simultaneous illumination with background red light. Light-adapted cells were incubated in the dark (observed under IR conditions) for 30 min and then irradiated with a blue-light microbeam of 3 or 10 W m 2 (Fig. 5, a and
c, respectively) simultaneously with IR light for 60 or 45 min,
respectively, followed by 30 W m 2 red light
over the whole cell area. Under these conditions chloroplast movement
before and after the transition from IR to red light was not affected.
Similarly, after 30 min of observation under IR conditions, the cells
were irradiated with background red light over the whole cell area.
Sixty minutes after the onset of the red-light irradiation, parts of
the cells were irradiated with a blue-light microbeam of 3 or 10 W
m 2 (Fig. 5, b and d, respectively). Again, we
observed the expected pattern of blue-light-induced chloroplast
relocation. Our data indicate that the blue-light-induced chloroplast
relocation was not affected by red light under LFR or HFR conditions
(Fig. 5).
A Brief Chloroplast-Avoidance Response Induced by Blue Light In traditional experiments HFR was usually induced by continuous blue-light irradiation. We studied whether chloroplast-avoidance responses could be induced by a brief blue-light irradiation in light-adapted prothallial cells (Figs. 6 and 7a). When the cells were irradiated with a blue-light microbeam of 30 W m 2 for 1 min and transferred to darkness,
inside-located chloroplasts began to move toward the outside of the
beam, as if they were avoiding the light (Fig.
7a, right panel, lines 3 and 4). In
contrast, outside-located chloroplasts moved toward the beam (Fig. 7a,
right panel, line 1). Most of the inside-located chloroplasts stopped outward movement within 10 min after the light was switched off. The
average duration of the outward movement was 6.2 ± 0.4 min (Fig.
7b). The outward movement of inside-located chloroplasts could also be
induced with a blue-light irradiation of 30 W
m 2 for 20 s (Fig.
8), but 6 s was not enough (data not
shown).
Light-induced chloroplast relocation was induced by a microbeam of
high-fluence blue light given in the center of fern prothallial cells.
When we observed the behavior of each chloroplast in a given cell
continuously, both LFRs and HFRs, even in a single cell, could be seen
outside and inside of the beam spot of blue light, respectively. This
result indicates that both LFR and HFR signals were elicited in the
beam-irradiated area, although it is not known whether they shared one
or more common photoreceptors. Furthermore, these findings suggest that
the LFR signal can be transferred long distances from the beam to the
cell periphery, but that the HFR signal cannot. In very high-fluence
light (30 W m
2 Present address: Division of Biological Regulation, National Institute for Basic Biology, Okazaki 444-8585, Japan. * Corresponding author; e-mail kagawa{at}nibb.ac.jp; fax 81-564-55-7611. Received May 21, 1998;
accepted November 22, 1998.
Abbreviations: HFR, high-fluence response. LFR, low-fluence response.
We are grateful to Dr. Jane Silverthorne of the University of California (Santa Cruz) for her critical reading of the manuscript.
Haupt W, Häder D-P (1994) Photomovement. In RE Kendrick, GHM Kronenberg, eds, Photomorphogenesis in Plants, Ed 2. Kluwer Academic Publishers, Dordrecht, The Netherlands, pp 707-732 Kagawa T, Wada M (1993) Light-dependent nuclear positioning in prothallial cells of Adiantum capillus-veneris. Protoplasma 177: 82-85 [CrossRef][Web of Science] Kagawa T, Wada M (1994) Brief irradiation with red or blue light induces orientational movement of chloroplasts in dark-adapted prothallial cells of the fern Adiantum. J Plant Res 107: 389-398 [CrossRef] Kagawa T, Wada M (1996) Phytochrome- and blue-light-absorbing pigment-mediated directional movement of chloroplasts in dark-adapted prothallial cells of fern Adiantum as analyzed by microbeam irradiation. Planta 198: 488-493 [CrossRef][Web of Science] Kanegae T, Wada M (1998) Isolation and characterization of the plant blue light photoreceptor (cryptochrome) homologousgenes of the fern Adiantum capillus-veneris. Mol Gen Genet 259: 345-353 [CrossRef][Web of Science][Medline] Kraml M, Büttner G, Haupt W, Herrmann H (1988) Chloroplast orientation in Mesotaenium: the phytochrome effect is strongly potentiated by interaction with blue light. Protoplasma S1: 172-179
Nozue K,
Kanegae T,
Imaizmi T,
Fukoda S,
Okamoto H,
Yeh K-C,
Lagarias JC,
Wada M
(1998)
A phytochrome from the fern Adiantum with features of putative photoreceptor NPHI.
Proc Natl Acad Sci USA
95:
15826-15830
Trojan A, Gabrys H (1996) Chloroplast distribution in Arabidopsis thaliana (L.) depends on light conditions during growth. Plant Physiol 111: 419-425 [Abstract] Wada M, Grolig F, Haupt W (1993) Light-oriented chloroplast positioning: contribution to progress in photobiology. J Photochem Photobiol 31: 415-418 Wada M, Kanegae T, Nozue K, Fukuda S (1997) Cryptogam phytochrome. Plant Cell Environ 20: 685-690 [CrossRef] Yatsuhashi H, Kadota A, Wada M (1985) Blue- and red-light action in photo-orientation of chloroplasts in Adiantum protonemata. Planta 165: 43-50 [CrossRef][Web of Science] Yatsuhashi H, Wada M (1990) High-fluence rate responses in the light-oriented chloroplast movement in Adiantum protonemata. Plant Sci 68: 87-94 [CrossRef] Zurzycki J (1980) Blue light-induced intracellular movement. In H Senger, eds, Blue Light Syndrome. Springer-Verlag, New York, pp 50-68
Copyright Clearance Center: 0032-0889/99/119//08
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