Altered etioplast development in phytochrome chromophore-deficient mutants

Inhibition of chromophore synthesis in the phytochrome-deficient aurea (au) and yellow-green-2 (yg-2) mutants of tomato (Solanum lycopersicum L.) results in a severe reduction of protochlorophyllide (Pchlide) accumulation in dark-grown hypocotyls. Experiments with apophytochrome-deficient mutants in...

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Bibliographic Details
Published in:	Planta Vol. 214; no. 2; pp. 314 - 325
Main Authors:	Terry, Matthew J., Ryberg, Margareta, Raitt, Catharine E., Page, Anton M.
Format:	Journal Article
Language:	English
Published:	Berlin Springer-Verlag 01-12-2001 Springer
Subjects:	Arabidopsis - genetics Arabidopsis - metabolism Biological and medical sciences Cotyledons Darkness Etioplasts Fluorescence Fundamental and applied biological sciences. Psychology Heme - metabolism Hypocotyl - enzymology Hypocotyl - growth & development Hypocotyls Microscopy, Electron Mutation NADP - metabolism Oxidoreductases - biosynthesis Oxidoreductases Acting on CH-CH Group Donors Peas Physical agents Phytochrome - genetics Phytochrome - metabolism Pisum sativum - genetics Pisum sativum - metabolism Plant cells Plant physiology and development Plants Plants, Genetically Modified Plastids Plastids - metabolism Plastids - ultrastructure Protochlorophyllide - metabolism Pyrroles - metabolism Seedlings Signal Transduction Solanum lycopersicum - enzymology Solanum lycopersicum - genetics Solanum lycopersicum - growth & development Tetrapyrroles Vegetative apparatus, growth and morphogenesis. Senescence Functional deficit Feedback regulation Biosynthesis Morphogenesis Arabidopsis thaliana Regulation(control) Cruciferae Dicotyledones Angiospermae Lycopersicon esculentum Development Solanaceae Intraspecific comparison Chloroplast Etioplast Chromophore Interspecific comparison Genetic variant Photomorphogenesis Grain legume Pyrrole copolymer Leguminosae Vegetable crop Metabolic precursor Pisum sativum Phytochrome Spermatophyta Mutation Experimental plant
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Summary:	Inhibition of chromophore synthesis in the phytochrome-deficient aurea (au) and yellow-green-2 (yg-2) mutants of tomato (Solanum lycopersicum L.) results in a severe reduction of protochlorophyllide (Pchlide) accumulation in dark-grown hypocotyls. Experiments with apophytochrome-deficient mutants indicate that the inhibition of Pchlide accumulation results from two separate effects: one dependent on the activity of phytochromes A and B1 and one phytochrome-independent effect that is attributed to a feedback inhibition of the tetrapyrrole biosynthesis pathway. Cotyledons only show phytochrome-independent inhibition of Pchlide synthesis. Analysis of NADPH:protochlorophyllide oxidoreductase levels by western blotting showed that the reduction in Pchlide in au and yg-2 is accompanied by a correlative, but less substantial, decrease in NADPH:protochlorophyllide oxidoreductase. Consistent with this result, in vivo fluorescence spectra demonstrate that both mutants are primarily deficient in non-phototransformable Pchlide. Analysis of etioplast structure indicates that plastid development in au and yg-2 is retarded in hypocotyls and partially impaired in cotyledons, again correlating with the reduction in Pchlide. Since Pchlide synthesis is also reduced in chromophore-deficient mutants of pea (Pisum sativum L.) and Arabidopsis thaliana (L.) Heynh. (Landsberg erecta) these results may be significant for explaining aspects of the phenotype of this mutant class that are independent of the loss of phytochrome.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	0032-0935 1432-2048
DOI:	10.1007/s004250100624