Abstract
Unilateral irradiation with red light (R) or blue light (BL) elicits positive curvature of the mesocotyl of maize (Zea mays L.) seedlings raised under R for 2 d from sowing and kept in the dark for 1 d prior to curvature induction. The fluenceresponse curve for R-induced mesocotyl curvature, obtained by measuring curvature 100 min after phototropic induction, shows peaks in two fluence ranges, designated first positive range (from the threshold to the trough), and second positive range (above the trough). The fluence-response curve for BL is similar to that for R but shifted two orders of magnitude to higher fluences. Blue light elicits the classical first positive curvature of the coleoptile, whereas this response is not found with R. Positive mesocotyl curvature induced by either R or BL is eliminated by R given from above just before the unilateral irradiation, whereas BL-induced coleoptile curvature is not eliminated. The above results collectively offer evidence that phototropic curvature of the mesocotyl is induced by R-sensitive photosystem(s). Mesocotyl curvature in the second positive range is reduced by vertical far-red light (FR) applied after phototropic induction with R, but is not affected by FR applied before R. Unilateral irradiation with FR following vertical irradiation with a high R fluence leads to negative curvature of the mesocotyl. It is concluded that mesocotyl curvature in the second positive range results from a gradient in the amount of the FR-absorbing form of phytochrome (Pfr) established across the plant axis. Mesocotyl curvature in the first positive range is inhibited by vertical FR given either before or after phototropic induction with R. Since the FR used here is likely to produce more Pfr than the very low fluences of R eliciting the mesocotyl curvature in the first positive range, it is assumed that FR reduces the response in this case by adding Pfr at both sides of the plant axis. By rotating seedlings on a clinostat with its axis horizontal, the kinetics of mesocotyl curvature can be studied in the absence of a counteracting gravitropic response. On the clinostat, the R-induced mesocotyl curvature develops after a lag, through two successive phases having different curvature rates, the late phase is slower than the early phase. Negative curvature of the coleoptile can be induced by either R or BL; the BL-induced negative curvature is found at fluences higher than those giving positive curvature. The clinostat experiments show that the negative coleoptile curvature induced by either R or BL is a gravitropic compensation for positive mesocotyl curvature.
Similar content being viewed by others
Abbreviations
- BL:
-
blue light
- FR:
-
far-red light
- Pfr:
-
phytochrome in the far-red-absorbing form
- Pr:
-
phytochrome in the red-absorbing form
- R:
-
red light
References
Atkins, G.A. (1936) The effect of pigment on phototropic response: a comparative study of reactions to monochromatic light. Ann. Bot. 50, 197–218
Bachmann, F., Bergann, F. (1930) Über die Wertigkeit von Strahlen verschiedener, Wellenlänge für die phototropische Reizung von Avena sativa. Planta 10, 744–755
Blaauw, O.H., Blaauw-Jansen, G. (1964) The influence of red light on the phototropism of Avena coleoptiles. Acta Bot. Neerl. 13, 541–552
Blaauw, O.H., Blaauw-Jansen, G., van Leeuwen, W.J. (1968) An irreversible red-light-induced growth response in Avena. Planta 82, 87–104
Briggs, W.R., Chon, H.P. (1966) The physiological versus the spectrophotometric status of phytochrome in corn coleoptiles. Plant Physiol. 41, 1159–1166
Briggs, W.R., Iino, M. (1983) Blue-light-absorbing photoreceptors in plants. Philos. Trans. R. Soc. London Ser. B (in press)
Chon, H.P., Briggs, W.R. (1966) Effect of red light on the phototropic sensitivity of corn coleoptiles Plant Physiol. 41, 1715–1724
Curry, G.M. (1969) Phototropism. In: Physiology of plant growth and development, pp. 243–273, Wilkins, M.B., ed. McGraw-Hill, London
Curry, G.M., Thimann, K.V., Ray, P.M. (1956) The base curvature response of Avena seedlings to the ultraviolet. Physiol. Plant. 9, 429–440
Dennison, D.S. (1979) Phototropism. In: Encyclopedia of plant physiology, N.S., vol. 7: Physiology of movements pp. 506–566, Haupt, W., Feinleib, M.E., eds. Springer, Berlin Heidelberg New York
Galston, A.W. (1959) Phototropism of stems, roots and coleoptiles. In: Encyclopedia of plant physiology, vol. 17–1, pp. 492–529, Ruhland, W., ed. Springer, Berlin Heidelberg NewYork
Iino, M. (1982a) Action of red light on indole-3-acetic-acid status and growth in coleoptiles of etiolated maize seedlings. Planta 156, 21–32
Iino, M. (1982b) Inhibitory action of red light on the growth of the maize mesocotyl: evaluation of the auxin hypothesis. Planta 156, 388–395
Iino, M., Carr, D.J. (1981) Safelight for photomorphogenetic studies: infrared radiation and infrared-scope. Plant Sci. Lett. 23, 262–268
Mandoli, D.F., Briggs, W.R. (1991) Phytochrome control of two low-irradiance responses in etiolated oat seedlings. Plant Physiol. 67, 733–739
Pratt, L.H., Briggs, W.R. (1966) Photochemical and nonphotochemical reactions of phytochrome in vivo. Plant Physiol. 41, 467–474
Schäfer, E., Lassig, T.-U., Schopfer, P. (1982) Phytochromecontrolled extension growth of Avena sativa L. seedlings. II. Fluence rate relationships and action spectra of mesocotyl and coleoptile responses. Planta 154, 231–240
Seyfried, M., Fukshansky, L. (1983) Light gradients in plant tissue. Appl. Opt. 22, 1402–1408
Shen-Miller, J., Gordon, S.A. (1967) Gravitational compensation and the phototropic response of oat coleoptiles. Plant Physiol. 42, 353–360
Shropshire, W., Jr., Mohr, H. (1970) Gradient formation of anthocyanin in seedlings of Fagopyrum and Sinapis unilaterally exposed to red and far-red light. Photochem. Photobiol. 12, 145–149
Thimann, K.V., Curry, G.M. (1960) Phototropism and phototaxis. In: Comparative biochemistry, vol. 1, pp 243–309, Mason, H.S., Florkin, M., eds., Academic Press, New York
Vanderhoef, L.N., Quail, P.H., Briggs, W.R. (1979) Red lightinhibited mesocotyl elongation in maize seedlings. Plant Physiol. 53, 1062–1067
Zimmerman, B.K., Briggs, W.R. (1963) Phototropic dosageresponse curves for oat coleoptiles. Plant Physiol. 38, 248–253
Author information
Authors and Affiliations
Additional information
C.I.W.-D.P.B. Publication No. 824
Rights and permissions
About this article
Cite this article
Iino, M., Briggs, W.R. & Schäfer, E. Phytochrome-mediated phototropism in maize seedling shoots. Planta 160, 41–51 (1984). https://doi.org/10.1007/BF00392464
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00392464