Actin-based photo-orientation movement of chloroplasts in plant cells
Department of Biology, Graduate School of Science, Osaka University, Toyonaka 560-0043, Japan
(e-mail: shingot{at}bio.sci.osaka-u.ac.jp)
Accepted 23 December 2002
![]() |
Summary |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Key words: chloroplast, photosynthesis, photo-orientation movement, actin cytoskeleton, Vallisneria gigantea, Spinacia oleracea
![]() |
Photo-orientation movement of chloroplasts |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
|
In most cases studied to date, blue light specifically induces chloroplast
movement under both dim and strong light
(Zurzycki, 1980;
Haupt and Scheuerlein, 1990
).
Recently, in the model plant Arabidopsis thaliana, flavoprotein
phototropins (phot1 and phot2) were identified as blue-light photoreceptors
that function in the light-induced relocation of chloroplasts
(Kagawa et al., 2001
;
Jarillo et al., 2001
;
Sakai et al., 2001
). On the
other hand, the involvement of phytochromes, another photo-morphogenic
photoreceptor family in plants (Furuya,
1993
), in the orientation movement of chloroplasts has been
demonstrated in algae (Haupt et al.,
1969
), mosses (Sato et al.,
2001
), ferns (Yatsuhashi,
1996
), and angiosperms (Dong et
al., 1995
). From the effects of linearly polarized light
(Zurzycki, 1967
) and microbeam
irradiation (Haupt et al.,
1969
), both blue-light photoreceptors and phytochromes are
postulated to be orderly arranged in the vicinity of the plasma membrane to
regulate the photo-orientation movement of chloroplasts
(Haupt and Scheuerlein, 1990
;
Yatsuhashi, 1996
).
Actin filaments are involved in the intracellular movement of chloroplasts
(Takagi, 2000). The anti-actin
drug cytochalasin inhibits the light-dependent movement of chloroplasts in
many kinds of plant cells, including those of algae
(Wagner et al., 1972
), mosses
(Sato et al., 2001
), ferns
(Kadota and Wada, 1992b
) and
angiosperms (Witztum and Parthasarathy,
1985
; Izutani et al.,
1990
; Tla
ka and
Gabry
, 1993
). Although the direct interaction of putative
myosin molecules with chloroplasts was suggested in a couple of plant species
based on immunolocalization studies (La
Claire, 1991
; La Claire et
al., 1995
, Liebe and Menzel,
1995
), it has been generally accepted that chloroplasts
participate only passively in the movement of the cytoplasmic matrix
(Haupt and Schönbohm,
1970
). Most of the plant myosins examined in the DNA sequences to
date belong to either class VIII or XI
(Liu et al., 2001
), and the
possible interaction of biochemically identified myosins from the alga
Chara (Yamamoto et al.,
1995
) and the angiosperm lily (Lilium longiflorum;
Yokota et al., 1995
) with cell
organelles has been investigated. The exact localization and roles of myosins
in the regulation of chloroplast movement remain to be clarified.
Concomitant with the light-dependent redistribution of chloroplasts, the
spatial reorganization of actin filaments has been shown in the coenocytic
alga Vaucheria (Blatt and Briggs,
1980; Blatt et al.,
1980
), the green algae Caulerpa
(Menzel and Elsner-Menzel,
1989
) and Mougeotia
(Mineyuki et al., 1995
) and
the pteridophytes Selaginella (Cox
et al., 1987
) and Adiantum
(Kadota and Wada, 1992a
).
Chloroplast movement in the green alga Dichotomosiphon is
microtubule-dependent (Maekawa and Nagai
1988
); however, chloroplasts that accumulated in cell apices after
photo-orientation movement were found to be associated with numerous fine
bundles of actin filaments (Fig.
2). Also, in vascular plants, actin filaments surrounding
chloroplasts have frequently been observed by light microscopy
(Kobayashi et al., 1987
;
Kadota and Wada, 1992a
;
Dong et al., 1996
;
Kandasamy and Meagher, 1999
).
In A. thaliana, disruption of the actin filaments by the anti-actin
drug latrunculin B led to the disruption of the intracellular arrangement of
chloroplasts (Kandasamy and Meagher,
1999
). These studies have pointed out the possibility that actin
filaments not only provide tracks for the movement of chloroplasts but also
function to anchor the chloroplasts at proper intracellular positions. The
different roles of the actin filaments may have resulted from the different
signalling pathways from the photoreceptor systems functioning under different
light conditions. We are investigating these aspects in higher plants, using
the monocotyledonous aquatic plant Vallisneria gigantea Graebner and
the dicotyledonous terrestrial plant Spinacia oleracea L.
(spinach).
|
![]() |
Accumulation response of chloroplasts in Vallisneria |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
|
|
|
Both far-red light and inhibitors of photosynthesis [dichlorophenyl
dimethylurea (DCMU), atrazine and tetraphenyl boron] antagonized the
red-light-induced accumulation of chloroplasts on the P side. However, the
modes of inhibition were completely different. Far-red light rapidly
suppressed the initial red-light-induced increase in the motility of
chloroplasts. The rates of migration of chloroplasts between the P side and
the A sides promptly returned to the dark control level. By contrast, in the
presence of DCMU, there was hardly any decline in chloroplast motility after
the initial increased motility of chloroplasts by red light
(Fig. 5). In fact, the
increased migration of chloroplasts between the P side and the A sides
continued for a long time and did not decrease as it did after dim-red-light
irradiation in the absence of DCMU. Thus, in either case, the number of
chloroplasts on the P side did not change because no imbalance in the rates of
migration of chloroplasts between the P side and the A sides occurred. We
consequently succeeded in distinguishing the effects of dim red light on the
motility of chloroplasts. Firstly, there is the rapid, red-light and
far-red-light reversible effect. Red light accelerates the motility of
chloroplasts, whereas far-red light inhibits this increased motility. This
effect is thought to be mediated by photoreceptor phytochromes. The other
effect is a much slower, photosynthesis-dependent suppression of the motility
of chloroplasts. We clarified that the reorganization of actin filaments is
involved in the latter photosynthesis-dependent process. Although we
identified a Ca2+-sensitive motor protein activity that interacts
with actin filaments in Vallisneria leaves
(Takagi 1997), its
intracellular localization has not been determined yet. The possible
involvement of the motor protein activity in the regulation of the motility of
chloroplasts remains to be investigated.
![]() |
Actin-dependent anchoring of chloroplasts |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
|
After accumulation on the P side under dim red light, the chloroplasts
became considerably resistant to centrifugal force
(Takagi et al., 1991;
Dong et al., 1998
). This effect
was antagonized by treatment with cytochalasin, which simultaneously brought
about the complete fragmentation of the honeycomb array of the actin filaments
surrounding the chloroplasts (Dong et al.,
1998
). Therefore, in Vallisneria, we demonstrated for the
first time that actin filaments not only drive the movement of chloroplasts
but also anchor the chloroplasts after the photo-orientation movement.
![]() |
Avoidance response of chloroplasts in Vallisneria |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Using microbeam irradiation, we found that the avoidance response of chloroplasts was induced locally only in the region exposed to blue light. Chloroplasts in the non-irradiated regions did not change their positions at all. The reorganization of the actin filaments was also induced only in the irradiated region, producing a 'hybrid' cell possessing both the actin filaments of a honeycomb array surrounding the motionless chloroplasts and the thick, straight bundles that did not come in contact with any chloroplasts (Fig. 6C). The thick, straight bundles of actin filaments most probably function as tracks for the unidirectional migration of chloroplasts from the irradiated region. The regulation of the configuration of actin filaments by blue light photoreceptors is under strict spatial control in individual epidermal cells.
![]() |
Interaction of chloroplasts with actin filaments in spinach |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
|
Because we succeeded in visualizing the actin filaments associated with chloroplasts in spinach mesophyll cells under dim light, we attempted to isolate such chloroplasts from the cells. In the cytoplasm obtained by squeezing manually dissected cells, we occasionally observed chloroplasts associated with actin filaments (Fig. 8). This suggested a possible direct interaction of chloroplasts with actin filaments; however, when chloroplasts were isolated after homogenization of the leaves and Percoll centrifugation, we could not detect any actin by immunoblotting of the final fraction, which was rich in intact chloroplasts (Fig. 9; lane 1). Actin filaments might have been detached from the chloroplasts during the isolation procedure. Finally, using such isolated intact chloroplasts, which are apparently free of actin filaments, we examined the possible binding of the exogenously added skeletal F-actin. As expected, F-actin co-sedimented with the intact chloroplasts, depending on the incubation time (Fig. 9; lanes 2 and 3).
|
|
![]() |
Concluding remarks |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Furthermore, as has already been pointed out by several eco-physiologists
(Evans and von Caemmerer,
1996), chloroplasts are almost always positioned along the cell
walls facing the intercellular spaces in the leaves
(Fig. 10). Although this may
be interpreted as indicating that chloroplasts have to capture much
CO2 even under spatially limited conditions
(Terashima et al., 1995
), we
know nothing about the mechanism of this simple phenomenon. To obtain a much
deeper insight into the photo-orientation movement of chloroplasts- one of the
most precisely regulated cellular responses in plants to environmental
stimuli- much more extensive collaboration among cell biologists and
eco-physiologists is essential.
|
![]() |
Acknowledgments |
---|
![]() |
References |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Blatt, M. R. and Briggs, W. R. (1980). Blue-light-induced cortical fiber reticulation concomitant with chloroplast aggregation in the alga Vaucheria sessilis. Planta 147,355 -362.
Blatt, M. R., Wessells, N. K. and Briggs, W. R. (1980). Actin and cortical fiber reticulation in the siphonaceous alga Vaucheria sessilis. Planta 147,363 -375.
Cox, G., Hawes, C. R., van der Lubbe, L. and Juniper, B. E. (1987). High-voltage electron microscopy of whole, critical-point dried plant cells. 2. Cytoskeletal structures and plastid motility in Selaginella. Protoplasma 140,173 -186.
Dong, X.-J., Nagai, R. and Takagi, S. (1998). Microfilaments anchor chloroplasts along the outer periclinal wall in Vallisneria epidermal cells through cooperation of PFR and photosynthesis. Plant Cell Physiol. 36,1299 -1306.
Dong, X.-J., Ryu, J.-H., Takagi, S. and Nagai, R. (1996). Dynamic changes in the organization of microfilaments associated with the photocontrolled motility of chloroplasts in epidermal cells of Vallisneria. Protoplasma 195, 18-24.
Dong, X.-J., Takagi, S. and Nagai, R. (1995). Regulation of the orientation movement of chloroplasts in epidermal cells of Vallisneria: cooperation of phytochrome with photosynthetic pigment under low-fluence-rate light. Planta 197,257 -263.
Evans, J. R. and von Caemmerer, S. (1996).
Carbon dioxide diffusion inside leaves. Plant Physiol.
110,339
-346.
Furuya, M. (1993). Phytochromes: their molecular species, gene families, and functions. Annu. Rev. Plant Physiol. Plant Mol. Biol. 44,617 -645.[CrossRef]
Haupt, W., Mörtel, G. and Winkelnkemper, I. (1969). Demonstration of different dichroic orientation of phytochrome Pr and Pfr. Planta 88,183 -186.
Haupt, W. and Scheuerlein, R. (1990). Chloroplast movement. Plant Cell. Environ. 13,595 -614.
Haupt, W. and Schönbohm, E. (1970). Light-oriented chloroplast movements. In Photobiology of Microorganisms (ed. P. Halldall), pp.283 -306. London: Wiley-Interscience.
Inoue, Y. and Shibata, K. (1974). Comparative examination of terrestrial plant leaves in terms of light-induced absorption changes due to chloroplast rearrangements. Plant Cell. Physiol. 15,717 -721.
Izutani, Y., Takagi, S. and Nagai, R. (1990). Orientation movements of chloroplasts in Vallisneria epidermal cells: different effects of light at low-and high-fluence rate. Photochem. Photobiol. 51,105 -111.
Jarillo, J. A., Gabry, H., Capel, J., Alonso, J. M.,
Ecker, J. R. and Cashmore, A. R. (2001). Phototropin-related
NPL1 controls chloroplast relocation induced by blue light.
Nature 410,952
-954.[CrossRef][Medline]
Kadota, A. and Wada, M. (1992a). Photoinduction of formation of circular structures by microfilaments on chloroplasts during intracellular orientation in protonemal cells of the fern Adiantum capillus-veneris. Protoplasma 167,97 -107.
Kadota, A. and Wada, M. (1992b). Photoorientation of chloroplasts in protonemal cells of the fern Adiantum as analyzed by use of video-tracking system. Bot. Mag. Tokyo 105,265 -279.
Kagawa, T., Sakai, T., Suetsugu, N., Oikawa, K., Ishiguro, S.,
Kato, T., Tabata, S., Okada, K. and Wada, M. (2001).
Arabidopsis NPL1: a phototropin homolog controlling the chloroplast
high-light avoidance response. Science
291,2138
-2141.
Kandasamy, M. K. and Meagher, R. B. (1999). Actin-organelle interaction: association with chloroplast in Arabidopsis leaf mesophyll cells. Cell Motil. Cytoskel. 44,110 -118.[CrossRef][Medline]
Kobayashi, H., Fukuda, H. and Shibaoka, H. (1987). Reorganization of actin filaments associated with the differentiation of tracheary elements in Zinnia mesophyll cells. Protoplasma 138,69 -71.
La Claire, J. W., II (1991). Immunolocalization of myosin in intact and wounded cells of the green alga Ernodesmis verticillata (Kutzing) Borgesen. Planta 184,209 -217.
La Claire, J. W., II, Chen, R. and Herrin, D. L. (1995). Identification of a myosin-like protein in Chlamydomonas reinhardtii (Chlorophyta). J. Phycol. 31,302 -306.
Liebe, S. and Menzel, D. (1995). Actomyosin-based motility of endoplasmic reticulum and chloroplasts in Vallisneria mesophyll cells. Biol. Cell 85,207 -222.[CrossRef][Medline]
Liu, L., Zhou, J. and Pesacreta, T. C. (2001). Maize myosins: diversity, localization and function. Cell Motil. Cytoskel. 48,130 -148.[CrossRef][Medline]
Maekawa, T. and Nagai, R. (1988). Reorganization of microtubule bundles in Dichotomosiphon: its implication in the light-induced translocation of cytoplasm. Protoplasma Suppl. 1,162 -171.
Menzel, D. and Elsner-Menzel, C. (1989). Actin-based chloroplast rearrangements in the cortex of the giant coenocytic green alga Caulerpa. Protoplasma 150, 1-8.
Mineyuki, Y., Kataoka, H., Masuda, Y. and Nagai, R. (1995). Dynamic changes in the actin cytoskeleton during the high-fluence rate response of the Mougeotia chloroplast. Protoplasma 185,222 -229.
Park, Y.-I., Chow, W. S. and Anderson, J. M.
(1996). Chloroplast movement in the shade plant Tradescantia
albiflora helps protect photosystem II against light stress.
Plant Physiol. 111,867
-875.
Raghavendra, A. S., Padmasree, K. and Saradadevi, K. (1994). Interdependence of photosynthesis and respiration in plant cells. Interactions between chloroplasts and mitochondria. Plant Sci. 97,1 -14.[CrossRef]
Sakai, T., Kagawa, T., Kasahara, M., Swartz, T. E., Christie, J.
M., Briggs, W. R., Wada, M. and Okada, K. (2001).
Arabidopsis nph1 and npl1: Blue light receptors that mediate both
phototropism and chloroplast relocation. Proc. Natl. Acad. Sci.
USA 98,6969
-6974.
Sato, Y., Wada, M. and Kadota, A. (2001).
Choice of tracks, microtubules and/or actin filaments for chloroplast
photo-movement is differentially controlled by phytochrome and a blue light
receptor. J. Cell Sci.
114,269
-279.
Senn, G. (1908). Die Gestalts- und Lageveranderung der Pflanzenchromatophoren. Leipzig Stuttgart: W. Engelmann.
Staiger, C. J. (2000). Signaling to the actin cytoskeleton in plants. Annu. Rev. Plant Physiol. Plant Mol. Biol. 51,257 -288.[CrossRef]
Takagi, S. (1997). Photoregulation of cytoplasmic streaming: cell biological dissection of signal transduction pathway. J. Plant Res. 110,299 -303.
Takagi, S. (2000). Roles for actin filaments in chloroplast motility and anchoring. In Actin: a Dynamic Framework for Multiple Plant Cell Functions (ed. C. J. Staiger, F. Baluska, D. Volkmann and P. Barlow), pp. 203-212.Dordrecht, The Netherlands: Kluwer Academic Publishers.
Takagi, S., Kamitsubo, E. and Nagai, R. (1991). Light-induced changes in the behavior of chloroplasts under centrifugation in Vallisneria epidermal cells. J. Plant Physiol. 138,257 -262.
Terashima, I., Ishibashi, M., Ono, K. and Hikosaka, K. (1995). Three resistances to CO2 diffusion: leaf-surface water, intercellular spaces and mesophyll cells. In Photosynthesis: from Light to Biosphere, vol.V (ed. P. Mathis), pp.537 -542.Dordrecht, The Netherlands: Kluwer Academic Publishers.
Tlaka, M. and Gabry
, H. (1993).
Influence of calcium on blue-light-induced chloroplast movement in Lemna
trisulca L. Planta
189,491
-498.
Wada, M. and Kagawa, T. (2001). Light-controlled chloroplast movement. In Photomovement (ed. D.-P. Hader and M. Lebert), pp.897 -924.Amsterdam, The Netherlands: Elsevier Science.
Wagner, G., Haupt, W. and Laux, A. (1972). Reversible inhibition of chloroplast movement by cytochalasin B in the green alga Mougeotia. Science 176,808 -809.
Witztum, A. and Parthasarathy, M. V. (1985). Role of actin chloroplast clustering and banding in leaves of Egeria, Elodea and Hydrilla. Eur. J. Cell Biol. 39, 21-26.
Yamaguchi, Y. and Nagai, R. (1981). Motile apparatus in Vallisineria leaf cells. I. Organization of microfilaments. J. Cell Sci. 48,193 -205.[Abstract]
Yamamoto, K., Kikuyama, M., Sutoh-Yamamoto, N., Kamitsubo, E. and Katayama, E. (1995). Myosin from alga Chara: unique structure revealed by electron microscopy. J. Mol. Biol. 254,109 -112.[CrossRef][Medline]
Yatsuhashi, H. (1996). Photoregulation systems for light-oriented chloroplast movement. J. Plant Res. 109,139 -146.
Yokota, E., McDonald, A. R., Liu, B., Shimmen, T. and Palevitz, B. A. (1995). Localization of a 170 kDa myosin heavy chain in plant cells. Protoplasma 185,178 -187.
Zurzycki, J. (1955). Chloroplast arrangement as a factor in photosynthesis. Acta Soc. Bot. Pol. 24, 27-63.
Zurzycki, J. (1957). The destructive effect of light on the photosynthetic apparatus. Acta Soc. Bot. Pol. 26,157 -175.
Zurzycki, J. (1967). Properties and localization of the photoreceptor active displacements of chloroplasts in Funaria hygrometrica. II. Studies with polarized light. Acta Soc. Bot. Pol. 36,143 -152.
Zurzycki, J. (1980). Blue light-induced intracellular movements. In The Blue Light Syndrome (ed. H. Senger), pp. 50-68. New York: Springer-Verlag.