Biliverdin Reductase-Induced Phytochrome Chromophore Deficiency in Transgenic Tobacco

• Published in: Plant physiology (Bethesda) Vol. 125; no. 1; pp. 266 - 277
• Main Authors: Beronda L. Montgomery, Franklin, Keara A., Terry, Matthew J., Thomas, Brian, Stephen D. Jackson, Crepeau, Marc W., Lagarias, J. Clark
• Format: Journal Article
• Language: English
• Published: Rockville, MD American Society of Plant Physiologists 01-01-2001; American Society of Plant Biologists
• Subjects: Agrobacterium tumefaciens - genetics; Anthocyanins - metabolism; Biological and medical sciences; Carotenoids; Cell Biology and Signal Transduction; Chlorophyll - analogs & derivatives; Chlorophyll - metabolism; Chlorophylls; Chromophores; Flowering; Fundamental and applied biological sciences. Psychology; Growth conditions; Hypocotyl - physiology; Light; Nicotiana - enzymology; Nicotiana - growth & development; Oxidoreductases Acting on CH-CH Group Donors - genetics; Oxidoreductases Acting on CH-CH Group Donors - metabolism; Phenotypes; Photoperiod; Physical agents; Phytochrome - metabolism; Plant physiology and development; Plants; Plants, Genetically Modified - enzymology; Plants, Genetically Modified - growth & development; Plastids; Recombinant Proteins - metabolism; Seedlings; Transgenic plants; Vegetative apparatus, growth and morphogenesis. Senescence; Enzyme; Environmental factor; Biosynthesis; Nicotiana tabacum; Photobiology; Structure function relationship; Regulation(control); Dicotyledones; Light; Angiospermae; Phytochrome; Biliverdin reductase; Flowering; Spermatophyta; Transgenic plant; Oxidoreductases; Solanaceae; Experimental plant; Elongation; Chromophore
• ISSN: 0032-0889; 1532-2548
• DOI: 10.1104/pp.125.1.266

Targeted expression of mammalian biliverdin IXα reductase (BVR), an enzyme that metabolically inactivates linear tetrapyrrole precursors of the phytochrome chromophore, was used to examine the physiological functions of phytochromes in the qualitative short-day tobacco (Nicotiana tabacum cv Maryland Mammoth) plant. Comparative phenotypic and photobiological analyses of plastid- and cytosol-targeted BVR lines showed that multiple phytochrome-regulated processes, such as hypocotyl and internode elongation, anthocyanin synthesis, and photoperiodic regulation of flowering, were altered in all lines examined. The phytochrome-mediated processes of carotenoid and chlorophyll accumulation were strongly impaired in plastid-targeted lines, but were relatively unaffected in cytosol-targeted lines. Under certain growth conditions, plastid-targeted BVR expression was found to nearly abolish the qualitative inhibition of flowering by long-day photoperiods. The distinct phenotypes of the plastid-targeted BVR lines implicate a regulatory role for bilins in plastid development or, alternatively, reflect the consequence of altered tetrapyrrole metabolism in plastids due to bilin depletion.