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plant biotechnology fails to increase yields of food crops



The article below shows a rational analysis of some benefits of crop
genetic modification  and the inability of plant biotechnology to
increase yields. It is clear that knowledge of genetics and and the
mechanics of genetic modification certainly substantiate that
biotechnology has failed and will fail to increase yields for some time
to come. In contrast plant breeding has been and is still very effective
in increasing yields.
Why then do "experts" from government, universities and FAO-WHO still
proclaim that only biotech can feed the starving world? For the most
part the answer  seems to lie in what should be termed the "Enron"
syndrome, or get big bucks fast and just lie like crazy.

Trends in Plant Science volume 8, Feb. 2003

Plant biotechnology and breeding: allied for years to come, Pages 70-75
Piero Morandini and Francesco Salamini

Agricultural biotechnology has the potential to develop more-sustainable
farming practices. For instance, plants expressing single insecticidal
proteins, such as Bt cotton, reduce the use of exogenous pesticides . This
application of biotechnology usually requires the transfer of single
genes from
distantly related species and, in spite of the problem of acceptance by
consumers, farmers in developed and developing countries have readily taken
them up. A less attractive application of biotechnology, which nevertheless
holds great promise, is the rational and selective alteration of metabolism
(the so-called `metabolic engineering') to increase the production of
endogenous metabolites or to achieve the synthesis of metabolites not
produced
by plants. Metabolic engineering in plants has indeed yielded remarkable
and
encouraging results by increasing the yield of minor components, such as
vitamin A, vitamin E and essential oil , as well as the composition of
major
components, such as fatty acid (e.g.  or starch , and by engineering
entirely
new pathways, as in the case of polyhydroxyalkanoates [7]. The alternative
possibility, aimed at improving yields in already abundant metabolic
products,
such as starch, has been less successful and has been unable to yield
viable
market products. In certain cases, results were even contrary to
expectations:
attempts at increasing sink strength and starch accumulation in potato
tubers
by increasing sucrose hydrolysis and metabolism, led to the induction of
glycolysis but to a decrease in starch content . By contrast, plant
breeding
has been extremely successful in increasing yields, even though, as a
technology, it is purely empirical and based on established practices
rather
than on understanding the molecular-physiological bases of the traits under
selection. Are there reasons to explain this contradiction? We argue
that plant
breeding will not be substituted in a few years by plant biotechnology,
rather
the two different approaches are and will be cooperating for years to come.