Transformation systems plants

Wang, J. Oard, J.H. Rice ubiquitin promoters deletion analysis and potential usefulness in plant transformation systems. Plant Cell Rep. 2003, 22 (2), 129-134. 

The stable transformation of plants has been used routinely as a method to express vaccine and therapeutic proteins. A number of disadvantages such as the length of time taken for transgenic plants to be generated and containment (i.e., preventing the escape of transgenes into the environment) have brought about a search for alternative methods by which to express proteins in plants. One such alternative is the utilization of plant virus expression systems. 

Figure 13. Agrobacterium tumefaciens, the natural transformation system for plants. The bacterium contains a circular piece of DNA, the Ti-plasmid. The bacterium infects a dicotyledonous plant and transfers the T-DNA from the Ti-plasmid to the plant chromosomal DNA causing a tumor to form. The tumor is called a "crown gall". The gall, or teratoma, can be removed from the plant and placed into culture on medium without exogenous hormones.

As the toxin and allergen are both proteins and have previously been identified and cloned, it is possible to use transgenic technology to block their expression. This approach is being pursued, and has resulted in the development of a transformation system for castor, a plant that had proven to be recalcitrant to transformation and regeneration of intact plants (39). 

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]. 

A GM assembly plant located in Fremont, CaMfomia was considered until 1982, the year it ended operations, the worst plant in the GM system and in the auto industry as whole. For years, the plant presented dismay levels of quality, low productivity, and prevrilent problems of absenteeism and turnover. The plant was reopened two years later under a new joint venture with Toyota. Changes focusing primarily on the relationship between workers and management, the oigemizationeil structure, and the widespread use of teamwork transformed the plant in one of the most productive ones of the GM system, with high levels of employee satisfaction and very low levels of absenteeism (Levine, 1995). 

Procedures have been developed for the transformation of opium poppy plants 317,318), root cultures 319,320), and cell cultures 321), E. califomica plants 322), root cultures 233,319), and cell cultures 232), and T. flavum plants 323). These transformation systems have provided the opportunity to alter the activity of individual enzymes of BA biosynthesis, and to examine the consequences of such modifications on the accumulation of pathway products and intermediates. 

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