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The phytochrome-deficient pcd1 mutant of pea is unable to convert heme to biliverdin IXα

The phytochrome-deficient pcd1 mutant of pea is unable to convert heme to biliverdin IXα
The phytochrome-deficient pcd1 mutant of pea is unable to convert heme to biliverdin IXα

We isolated a new pea mutant that was selected on the basis of pale color and elongated internodes in a screen under white light. The mutant was designated pcd1 for phytochrome chromophore deficient. Light-grown pcd1 plants have yellow-green foliage with a reduced chlorophyll (Chl) content and an abnormally high Chl a/Chl b ratio. Etiolated pcd1 seedlings are developmentally insensitive to far-red light, show a reduced response to red light, and have no spectrophotometrically detectable phytochrome. The phytochrome A apoprotein is present at the wild-type level in etiolated pcd1 seedlings but is not depleted by red light treatment. Crude phytochrome preparations from etiolated pcd1 tissue also lack spectral activity but can be assembled with phycocyanobilin, an analog of the endogenous phytochrome chromophore phytochromobilin, to yield a difference spectrum characteristic of an apophytochrome-phycocyanobilin adduct. These results indicate that the pcd1-conferred phenotype results from a deficiency in phytochrome chromophore synthesis. Furthermore, etioplast preparations from pcd1 seedlings can metabolize biliverdin (BV) IXα but not heme to phytochromobilin, indicating that pcd1 plants are severely impaired in their ability to convert heme to BV IXα. This provides clear evidence that the conversion of heme to BV IXα is an enzymatic process in higher plants and that it is required for synthesis of the phytochrome chromophore and hence for normal photomorphogenesis.

1040-4651
55-67
Weller, James L.
96be1cd9-b580-4e2d-9376-e50950d2ab35
Terry, Matthew J.
a8c2cd6b-8d35-4053-8d77-3841c2427c3b
Rameau, Catherine
10207aaf-8307-4368-a573-e299b22c98fe
Reid, James B.
782bf949-2d53-47ab-a615-2f4468d76f26
Kendrick, Richard E.
37bc46ac-ccf3-4d45-a77a-6b1879f190c7
Weller, James L.
96be1cd9-b580-4e2d-9376-e50950d2ab35
Terry, Matthew J.
a8c2cd6b-8d35-4053-8d77-3841c2427c3b
Rameau, Catherine
10207aaf-8307-4368-a573-e299b22c98fe
Reid, James B.
782bf949-2d53-47ab-a615-2f4468d76f26
Kendrick, Richard E.
37bc46ac-ccf3-4d45-a77a-6b1879f190c7

Weller, James L., Terry, Matthew J., Rameau, Catherine, Reid, James B. and Kendrick, Richard E. (1996) The phytochrome-deficient pcd1 mutant of pea is unable to convert heme to biliverdin IXα. The Plant Cell, 8 (1), 55-67. (doi:10.1105/tpc.8.1.55).

Record type: Article

Abstract

We isolated a new pea mutant that was selected on the basis of pale color and elongated internodes in a screen under white light. The mutant was designated pcd1 for phytochrome chromophore deficient. Light-grown pcd1 plants have yellow-green foliage with a reduced chlorophyll (Chl) content and an abnormally high Chl a/Chl b ratio. Etiolated pcd1 seedlings are developmentally insensitive to far-red light, show a reduced response to red light, and have no spectrophotometrically detectable phytochrome. The phytochrome A apoprotein is present at the wild-type level in etiolated pcd1 seedlings but is not depleted by red light treatment. Crude phytochrome preparations from etiolated pcd1 tissue also lack spectral activity but can be assembled with phycocyanobilin, an analog of the endogenous phytochrome chromophore phytochromobilin, to yield a difference spectrum characteristic of an apophytochrome-phycocyanobilin adduct. These results indicate that the pcd1-conferred phenotype results from a deficiency in phytochrome chromophore synthesis. Furthermore, etioplast preparations from pcd1 seedlings can metabolize biliverdin (BV) IXα but not heme to phytochromobilin, indicating that pcd1 plants are severely impaired in their ability to convert heme to BV IXα. This provides clear evidence that the conversion of heme to BV IXα is an enzymatic process in higher plants and that it is required for synthesis of the phytochrome chromophore and hence for normal photomorphogenesis.

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More information

Published date: January 1996

Identifiers

Local EPrints ID: 182699
URI: http://eprints.soton.ac.uk/id/eprint/182699
ISSN: 1040-4651
PURE UUID: 1e63e8cd-de06-4a26-a092-5a05217427f3
ORCID for Matthew J. Terry: ORCID iD orcid.org/0000-0001-5002-2708

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Date deposited: 18 May 2011 10:23
Last modified: 09 Nov 2021 02:51

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Contributors

Author: James L. Weller
Author: Catherine Rameau
Author: James B. Reid
Author: Richard E. Kendrick

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