"With all the soils in the world that have been degraded by mineral
salts from fertilizer overuse and irrigation, salt tolerance may be
one of the most valuable traits that can be engineered into crops."
The theory is great. When I did my doctorate on salt tolerance in the
late 70's/early 80's I bought a book "The Genetic Engineering of
Osmoregulation" (date 1980) all about how to engineer salt tolerance
in plants, and it still resides on my bookshelf. 23 years later we
still have no great advances, and no wonder salt tolerant crop. I
think the reasons are twofold:
1) Salt tolerance involves many genes, all interacting (very complex).
So far the GM crops that have been produced tend to be rather simple
efforts involving the change in one gene (e.g. herbicide resistance).
2) Naturally salt tolerant plants grow VERY slowly, and have low
yields. Probably a lot of the energy which normally goes into growth
is going into making the plant tolerant. So even if we can transfer
the salt tolerance genes to a crop it may well slow the plant down,
and decrease its yield very considerably.
Best Wishes,
Martin Hodson