ISHS Acta Horticulturae 418: III International Symposium on Artificial Lighting in Horticulture
ROLES OF PHOTORECEPTORS AND ENDOGENOUS RHYTHMS IN THE PHOTOPERIODIC CONTROL OF FLOWERING |
| Author: | Peter J. Lumsden |
| Keywords: | Arabidopsis, circadian rhythm, entrainment, mutants, Pharbitis nil, phytochrome |
| Abstract:
Photoperiodism requires the participation of a photoperception system and a timing system. The photoreceptor phytochrome has been assumed to be the photoreceptor for light perception in photoperiodism. However, there are now known to be at least 3 different molecular species of phytochrome molecule. Evidence from mutants and transgenic plants indicating specific roles for different molecular species, and for the blue-light photoreceptor, is discussed. The accepted view has also been that time measurement is based on a circadian rhythm, the characteristics of which are a changing sensitivity to light. More recently it has been suggested that, in short-day plants, a semidian (12 hour) rhythm is the basis of time measurement, but the data for this assertion can also be explained in terms of circadian rhythmicity. Of more interest is whether the control by light of the phase of rhythms (light-on / light-off) is significantly different in long and short-day plants. | |
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