Summary
The binding of phytochrome to a particulate fraction in extracts from hypocotyl hooks of etiolated Cucurbita pepo L. seedlings has been examined as a function of the light dose and P fr level established in vitro. As the steady-state level of P fr transiently established in the 500×g supernatant is increased, so the level of P r subsequently pelletable at 20 000×g increases up to a saturation level. Increasing both the time and irradiance parameters of the light dose while holding the steady-state P fr level constant, results similarly in increasing P r pelletability. This agrees with results obtained previously with in-vivo irradiations of maize coleoptiles. Thus, like the in-vivo response, phytochrome binding in vitro appears to be a function of the total number of molecules converted to the P fr form during the irradiation period.
Abbreviations
- P fr :
-
far-red-absorbing form of phytochrome
- P r :
-
red-absorbing form of phytochrome
References
Marmé, D., Boisard, J., Briggs, W. R.: In vitro binding properties of phytochrome to a membrane fraction. Proc. nat. Acad. Sci. (Wash.) 70, 3861–3865 (1973)
Quail, P. H.: Particle-bound phytochrome: spectral properties of bound and unbound fractions. Planta (Berl.) 118, 345–355 (1974)
Quail, P. H., Marmé, D., Schäfer, E.: Particle-bound phytochrome from maize and pumpkin. Nature (Lond.) New Biol. 245, 189–191 (1973)
Quail, P. H., Schäfer, E.: Particle-bound phytochrome: a function of light dose and steady-state P fr concentration. J. Memb. Biol., in press (1974)
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Quail, P.H. In-vitro binding of phytochrome to a particulate fraction: A function of light dose and steady-state P fr level. Planta 118, 357–360 (1974). https://doi.org/10.1007/BF00385585
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DOI: https://doi.org/10.1007/BF00385585