Feedback inhibition of chlorophyll synthesis in the phytochrome chromophore-deficient aurea and yellow-green-2 mutants of tomato


Terry, Matthew J. and Kendrick, Richard E. (1999) Feedback inhibition of chlorophyll synthesis in the phytochrome chromophore-deficient aurea and yellow-green-2 mutants of tomato. Plant Physiology, 119, (1), 143-152. (doi:10.1104/pp.119.1.143). (PMID:9880355).

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Description/Abstract

The aurea(au) and yellow-green-2(yg-2) mutants of tomato (Solanum lycopersicum L.) are unable to synthesize the linear tetrapyrrole chromophore of phytochrome, resulting in plants with a yellow-green phenotype. To understand the basis of this phenotype, we investigated the consequences of the au andyg-2 mutations on tetrapyrrole metabolism. Dark-grown seedlings of both mutants have reduced levels of protochlorophyllide (Pchlide) due to an inhibition of Pchlide synthesis. Feeding experiments with the tetrapyrrole precursor 5-aminolevulinic acid (ALA) demonstrate that the pathway between ALA and Pchlide is intact inau and yg-2 and suggest that the reduction in Pchlide is a result of the inhibition of ALA synthesis. This inhibition was independent of any deficiency in seed phytochrome, and experiments using an iron chelator to block heme synthesis demonstrated that both mutations inhibited the degradation of the physiologically active heme pool, suggesting that the reduction in Pchlide synthesis is a consequence of feedback inhibition by heme. We discuss the significance of these results in understanding the chlorophyll-deficient phenotype of the au andyg-2 mutants.

Item Type: Article
ISSNs: 0032-0889 (print)
0032-0889 (electronic)
Subjects: Q Science > QH Natural history > QH301 Biology
Q Science > QK Botany
Q Science > QP Physiology
Divisions: University Structure - Pre August 2011 > School of Biological Sciences
ePrint ID: 182697
Date Deposited: 18 May 2011 10:18
Last Modified: 27 Mar 2014 19:38
URI: http://eprints.soton.ac.uk/id/eprint/182697

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