Feedback Inhibition of Chlorophyll Synthesis in the Phytochrome Chromophore-Deficient aurea and yellow-green-2 Mutants of Tomato
AUTOR(ES)
Terry, Matthew J.
FONTE
American Society of Plant Physiologists
RESUMO
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 and yg-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 in au 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 and yg-2 mutants.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=32213Documentos Relacionados
- Complementation of phytochrome chromophore-deficient Arabidopsis by expression of phycocyanobilin:ferredoxin oxidoreductase
- Genetic and Chlorophyll Studies of a Yellow-Green Mutant in Muskmelon
- Physiology of the Yellow-Green 6 Gene in Tomato: A Possible Interrelationship between the Phenotypic Expressions of the Yellow-Green 6 Gene Mutation and the Gibberellins 12
- A Factor for Yellow-Green Chlorophyll Color in Maize and Its Linkage Relations
- A Factor for Yellow-Green Chlorophyll Color in Maize and Its Linkage Relations