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Bioscience in brief

Plant genetics and crop breeding

Why do breeders backcross elite events into elite varieties?

This approach much simplifies future breeding programmes: having a large number of independent transformation events, such as 20 virus resistant sorghum varieties each with a different insertion in the plant genome, would make targeted breeding very difficult. For future plant breeding programmes it is essential that material can be freely used.

Some crop varieties may be much more ameanable than other to genetic transformation.

New technologies have greatly reduced the time required for a backrossing programme. A typical backcrossing project for e.g. maize takes now 18 months, and delivers a set of several dozens of parent lines for hybrid seed production. For other crops similar reductions in time lines are routinely achieved in breeding.

The unit of regulation in GM crops is the event. In other words, each separate insertion locus of a gene in a crop requires a full biosafety assessment. The reason for this approach is that regulatory bodies have, at the start, taken the view that a biosafety assessment has three components:
(1) the nature of the host plant;
(2) the inserted new gene(s); and
(3) the location of the insert as a determinant of interactions that might have the potential to affect safety parameters.

Almost all biosafety professionals take the view that this is unnecessary duplication, and that, provided that separate events have been assessed for the location of the insert and do not interfere with a native gene, one biosafety file could cover many separate events.