Polyester synthesis in transplastomic tobacco (Nicotiana tabacum L.): significant contents of polyhydroxybutyrate are associated with growth reduction

The pathway for synthesis of polyhydroxybutyrate (PHB), a polyester produced by three bacterial enzymes, was transferred to the tobacco plastid genome by the biolistic transformation method. The polycistronic phb operon encoding this biosynthetic pathway was cloned into plastome transformation vecto...

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Bibliographic Details
Published in:Plant cell reports 2003-06, Vol.21 (9), p.891-899
Main Authors: LÖSSL, A, EIBL, C, HARLOFF, H.-J, JUNG, C, KOOP, H.-U
Format: Article
Language:English
Subjects:
Biological and medical sciences
Blotting, Southern
Chromatography, Gas
Chromatography, High Pressure Liquid
Fertility
Fundamental and applied biological sciences. Psychology
Gas chromatography
Hydroxybutyrates - metabolism
Male sterility
Nicotiana - growth & development
Nicotiana - metabolism
Plants, Genetically Modified - growth & development
Plants, Genetically Modified - metabolism
Plastids
Polyhydroxybutyrate
Polymerase Chain Reaction
Polymers
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Summary:The pathway for synthesis of polyhydroxybutyrate (PHB), a polyester produced by three bacterial enzymes, was transferred to the tobacco plastid genome by the biolistic transformation method. The polycistronic phb operon encoding this biosynthetic pathway was cloned into plastome transformation vectors. Following selection and regeneration, the content and structure of plant-produced hydroxybutyrate was analysed by gas chromatography. Significant PHB synthesis was limited to the early stages of in vitro culture. Within the transformants, PHB synthesis levels were highly variable. In the early regeneration stage, single regenerates reached up to 1.7% PHB in dry weight. At least 70% of plant-produced hydroxybutyric acid was proven to be polymer with a molecular mass of up to 2,500 kDa. PHB synthesis levels of the transplastomic lines were decreasing when grown autotrophically but their phb transcription levels remained stable. Transcription of the three genes is divided into two transcripts with phbB being transcribed separately from phbC and phbA. In mature plants even low amounts of PHB were associated with male sterility. Fertility was only observed in a mutant carrying a defective phb operon. These results prove successful expression of the entire PHB pathway in plastids, concomitant, however, with growth deficiency and male sterility.
ISSN:0721-7714
1432-203X
DOI:10.1007/s00299-003-0610-0