Translator Disclaimer
1 June 2001 Spectroscopic Detection of a Phytochrome-like Photoreceptor in the Myxomycete Physarum polycephalum and the Kinetic Mechanism for the Photocontrol of Sporulation by Pfr
Author Affiliations +
Abstract

Sporulation of the true slime mold Physarum polycephalum (Myxomycetales) can be triggered by the far-red/red reversible Physarum phytochrome. Physarum plasmodia were analyzed with a purpose-built dual-wavelength photometer that is designed for phytochrome measurements. A photoreversible absorbance change at 670 nm was monitored after actinic red (R) and far-red (FR) irradiation of starved plasmodia, confirming the occurrence of a phytochrome-like photoreceptor in Physarum spectroscopically. These signals were not found in growing plasmodia, suggesting the Physarum phytochrome to be synthesized during starvation, which makes the cells competent for the photoinduction of sporulation. The photoconversion rates by R and FR light were similar in the phytochromes of Physarum and etiolated oat shoots. In dark-grown Physarum plasmodia that had not been preexposed to any light only R induced a detectable absorbance change while FR did not. This indicates that most (at least 90%) of the photoreversible pigment occurs in the red-absorbing form. Since the effectiveness of FR in triggering sporulation was enhanced by preirradiation with R, it is concluded that at least part of the Pr can be photoconverted to the active Pfr photoreceptor species. We propose a kinetic mechanism for the photocontrol of sporulation by photoconversion of Pfr, which may also hold for the high-irradiance response to FR in Arabidopsis and Cuscuta.

Tilman Lamparter and Wolfgang Marwan "Spectroscopic Detection of a Phytochrome-like Photoreceptor in the Myxomycete Physarum polycephalum and the Kinetic Mechanism for the Photocontrol of Sporulation by Pfr," Photochemistry and Photobiology 73(6), 697-702, (1 June 2001). https://doi.org/10.1562/0031-8655(2001)073<0697:SDOAPL>2.0.CO;2
Received: 12 January 2001; Accepted: 1 February 2001; Published: 1 June 2001
JOURNAL ARTICLE
6 PAGES

This article is only available to subscribers.
It is not available for individual sale.
+ SAVE TO MY LIBRARY

SHARE
ARTICLE IMPACT
RIGHTS & PERMISSIONS
Get copyright permission
Back to Top