Nopaline synthase gene

Fig. 7. Diagrams of the schemes for modifying levels of A, alcohol dehydrogenase and B, pyruvate decarboxylase activity and testing for survival of anoxia. In A, constructs contain the 35S promoter of the cauliflower mosaic virus (35S) driving expression of the cotton Adh cDNA in either the sense (Adh) or antisense (hdA) orientation, linked to the 3 termination signal of the nopaline synthase gene (Nos). Alternatively, the expression of cotton Adh cDNA is under control of the pea Adh promoter sequence (pea Adh). In B, either the 35S promoter or the pea Adh promoter is used to drive expression of the maize pyruvate decarboxylase cDNA (Pdc), linked to a Nos 3 termination sequence. Constructs are introduced into cotton via Agrobacterium tumefaciens-mediated infection of cotton. Transformed cotton callus is then assayed for its ability to survive anoxia.

The E. coli mutant EPSPS gene was engineered into a plant expression vector (pMON8078) and used for transformation of tobacco leaf discs. In this construct, the mutant EPSPS gene was driven by the CaMV 35S promoter and the 3 -polyadenylation signal was derived from the nopaline synthase gene. 

Figure 6. Structure of /3-glucuronidase expression cassettes. TER is a 260 bp polyadenylation signal from the nopaline synthase gene (50). The degradative activity of a "bad batch" of Smal was used to make three different reading frames at lacZ and GUS. Translational and transcriptional fusions can easily be made in this vector.

Very little is known about plant terminators. It has not been determined whether an animal terminator can be functional in plants or not. Until such information is available, it is safer to use a plant terminator for the maximum expression of a foreign gene. The nopaline synthase nos terminator is most frequently used although several other plant terminators have also been isolated. 

Fig. 1. Schematic representation of Elcd expression cassette. CaMV 35Sp, cauliflower mosaic virus promoter NOS, nopaline synthase transcription termination signal Elcd, catalytic domain of El gene VSPP, soybean vegetative storage protein P leader sequence to target the protein to apoplast (15).

Barta A. The expression of a nopaline synthase human growth hormone chimaeric gene in transformed tobacco and sunflower callus tissue. Plant Mol. Biol., 1986 6 347-357. 

In plants, antisense RNA or otiier gene disruption methods have been used to reduce the activity of nopaline synthase (28,29), chloramphenicol acetyltransferase (30, 31), chalcone synthase (32-34), polygalacturonase (35,36), phosphinothricin acetyltransferase (37), p-glucuronid e (38,39), granule-bound starch synthase (40), Rubisco (7,41,42), 1-aminocyclopropane-l-carboxylate synthase (43) and oxidase (44-46), phenylalanine ammonia lyase (PAL) (47), stearoyl-acyl carrier protein... 

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