Articles
GENETIC MANIPULATION OF TEMPERATE FRUIT PLANTS: IMPLICATIONS FOR THE FUTURE ROLE OF PLANT GROWTH REGULATORS
The roles of micropropagation, somaclonal variation, in vitro mutagenesis, protoplast technology and gene transfer are examined for their capacity to control form and habit, cropping potential and plant propagation.
These techniques may influence all aspects of fruit production, but with the exception of gene transfer methods, are all ‘uncontrolled’ in the sense that although a desired variant character may be produced in a given cultivar, it may also be accompanied by other undesired changes that may lead to loss of clonal fidelity.
Obviously, where these techniques are successful it may be expected that PGR application will be reduced, but probably not replaced, since PGR technology will still be required for the ‘fine tuning’ of some of these processes.
Because of the relative newness of genetic manipulation techniques, there is very little evidence to show whether or not they will affect the short or long term future of PGR application.
Although it is possible to transfer foreign genes into fruit crops using plasmid vectors in agrobacteria, the range of their application and their effect on PGR technology in the short term is likely to be minimal.
It will prove possible to manipulate the form and density of root systems by producing genetic chimeras using Agrobacterium rhizogenes, but assessing the value of such methods requires full scale field trials, and these have yet to be carried out.
Since most of the important biological processes that affect fruit production are under polygenic control, there is no prospect in the near future of gene transfer affecting the use of PGRs, although the availability of herbicide tolerance genes may prove an exception.
It is concluded that in the short term, at least, the development of PGR technology will be impacted more by an environmentally aware public than by the implementation of genetic manipulation techniques.