Characterization of tobacco expressing functional oat phytochrome. Domains responsible for the rapid degradation of Pfr are conserved between monocots and dicots
- Univ. of Wisconsin, Madison (United States)
- E.I.du Pont de Nemours and Co., Wilmington, DE (United States)
Constitutive expression of a chimeric oat phytochrome gene in tobacco (Nicotiana tabacum) results in the accumulation of a functional 124-kilodalton photoreceptor that markedly alters the phenotype of light-grown tobacco. Here, we provide a detailed phenotypic and biochemical characterization of homozygous tobacco expressing high levels of oat phytochrome. Phenotypic changes include a substantial inhibition of stem elongation, decreased apical dominance, increased leaf chlorophyll content, and delayed leaf senescence. Oat phytochrome synthesized in tobacco is indistinguishable from that present in etiolated oats, having photoreversible difference spectrum maxima at 665 and 730 nanometers, exhibiting negligible dark reversion of phytochrome - far red-absorbing from (Pfr) to phytochrome - red-absorbing form (Pr), and existing as a dimer with an apparent size of approximately 300 kilodaltons. Heterodimers between the oat and tobacco chromoproteins were detected. Endogenous tobacco phytochrome and transgenically expressed oat phytochrome are rapidly degraded in vivo upon photoconversion of Pr to Pfr. Breakdown of both oat and tobacco Pfr is associated with the accumulation of ubiquitin-phytochrome conjugates, suggesting that degradation occurs via the ubiquitin-dependent proteolytic pathway. This result indicates that the factors responsible for selective recognition of Pfr by the ubiquitin pathway are conserved between monocot and dicot phytochromes. More broadly, it demonstrates that the domains(s) within a plant protein responsible for its selective breakdown can be recognized by the degradation machinery of heterologous species.
- DOE Contract Number:
- FG02-88ER13968
- OSTI ID:
- 5699495
- Journal Information:
- Plant Physiology; (United States), Vol. 96:3; ISSN 0032-0889
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
PHYTOCHROMES
GENES
GENETIC ENGINEERING
MOLECULAR BIOLOGY
OATS
PHENOTYPE
PHOTOCHEMICAL REACTIONS
PLANT GROWTH
PLANT STEMS
TOBACCO
BIOTECHNOLOGY
CEREALS
CHEMICAL REACTIONS
GRAMINEAE
GROWTH
LILIOPSIDA
MAGNOLIOPHYTA
ORGANIC COMPOUNDS
PIGMENTS
PLANTS
PROTEINS
550200* - Biochemistry