Transgenic plants plastid

Fig. 2. Accumulation of PHA inclusions in Arabidopsis transgenic plants. Transgenic cell expressing the poly(3HB) pathway in the plastid showing accumulation of poly(3HB) inclusions (arrows) in the chloroplast of a leaf mesophyll cell. Bar represents 1 pm... 

The wild type ilvA gene was modified to target the protein to the plastid and expressed in A. thaliana. Transgenic plants showed a 20-fold increase in levels of 2-ketobutyrate as well as a large increase in 2-aminobutyrate, the transaminated product of 2-ketobutyrate [27, 41]. The levels of threonine remained stable whereas isoleucine concentration increased. Constitutive expression of the ilvA protein along with bktB, phaA, and phaC proteins in the plastids of A. thaliana led to the synthesis of poly(3HB-co-3HV) in the range of 0.2 - 0.8 % dry weight, with a HV level between 4-17 mol % [27,41]. Co-expression of the iso-... 

Since the first successful transformation of tobacco chloroplasts [83], expression systems based on the transformation of plant plastids has attracted the attention of plant biotechnologists. The features that make this technology so attractive are its potential for high protein yield, along with inherent biosafety features such as limited plastid transfer via pollen (due to maternal inheritance of plastid-encoded genes) [84] and the relatively low probability of transgene movement from the chloroplast to the nucleus [85, 86]. 

In summary the presented data clearly show that the bacterial LPA-AT is functionally expressed in plastids and eflfecitvely competes with the plastidial enzyme. Hence, transgenic plants have been developed which are capable of de novo biosynthesis of eukaryotic glycerolipids within plastids. In spite of this ability the formation of PG species carrying unsaturated fatty acids at both positions was largely prevented. Whether this is due to the substrate species selectivities of the enzymes involved in PG synthesis, is currently under investigation. 

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