| Résumé | The seedless grapes and the tangello are well known examples of novel horticultural achievement. These achievements are significant from a scientific as well as from a practical viewpoint. We can think of a great many other plants for which specific modifications would. be desirable. The development of hardy fruit crops and ornamentals for western Canada are an example. Developing plants resistant to diseases such as Fireblight or Dutch Elm disease is another important objective. These changes require genetic modifications. The usual procedures of plant breeding involves sexual crosses. These methods have been invaluable and will always be required. However, plant breeders recognize the need for making broad crosses in order to expand the gene pool and gain access to new genes representing desirable characteristics. Such a task is difficult because of incompatibility barriers in the pollination process, and interspecific crosses are very rare.
Pollination involves fuSion of sex cells. In the last 3-4 years a new idea has been proposed and. is being tested. Rather than fusing sex cells it may be possible to fuse somatic or asexual plant cells. On division the fused cells would give rise to hybrids which would contain chromosomes from separate species.
Such hybrids are available from animal cells. Since 1960 it has been possible to fuse cultured cells of man-mouse, mouse-rat etc. and obtain hybrids. However, these cells will always remain hybrid cells and organs are not produced. On the other hand, somatic plant cells can be cultured, and also be induced to differentiate and develop into complete plants. If it was possible to obtain hybrid plant cells, it may also be possible to develop hybrid plants by the cell fusion procedure. |
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