Agriculture Reference
In-Depth Information
genetically modified (GM) plants. Commencing in the 1980s genetic transforma-
tion brought the biggest technological advances in plant biology since the green
revolution. The first generation GM plants were herbicide, insect and virus resistant
genotypes and were widely adapted in agricultural species in the United States. The
initial commercial success of this technology in horticulture was the Flavr Savr
R
tomato (Grierson and Fray
1994
) which was initially widely accepted in the retail
marketplace in both the United States and Great Britain. In this cultivar antisense
technology was used to lower the level of poly-galacturonase enzyme during fruit
ripening. By 1997, however the product was withdrawn from the market because
of rapidly changing attitudes in consumer sentiment to genetically modified plants.
Another example of gene transfer applied to a major disease of a horticultural crop
was the development of papaya ringspot virus type P (PRSV-P) resistance in pa-
paya. Although transgenic papaya genotypes were developed for many countries
by use of coat protein-mediated resistance to induce silencing of viral genes (Gon-
salves
1998
), and the technology has been available for 20 years, they have been
grown for commercial production only in Hawaii and in some regions of China.
Many markets, such as the EU and Japan still refuse to accept transgenic fruits.
In addition, many governments are reluctant to allow commercial production of
crops that are genetically modified by transgenetic engineering. The resistance has
been fuelled by over-dramatised and unsubstantiated claims by green movements
and consequential effects on many governments worldwide, who often depend on
coalitions with green parties to stay in power. The twenty-first century has also seen
a change in the attitude to science in some quarters from very positive to negative,
and GM technology has been used as a scapegoat by many organisations intent on
promoting negative views of science and its value to an ever-changing world. A
tragic consequence of this attitude has been the refusal of numerous governments
worldwide to accept golden rice (Potrykus
2001
) as a solution to vitamin A defi-
ciency. Six thousand children die daily from vitamin A deficiency; however, such is
the hostility to GM foods that this obvious solution to the problem is being ignored.
Other factors in the GM debate show that acceptance or rejection of scientific
breakthroughs is now based on more complex socioeconomic and political reasons.
One objection to GMOs has been caused by the huge number of patents that have
been applied to this technology. This has in part been caused by the pressure on
scientists to control intellectual property (IP) on their discoveries, to produce in-
come and profit, and reduce dependence on governments to provide funding for
research. This has led to legitimate concerns on the effect of IP on the cost of food
and longer term prospects of food monopolies and price control.
By contrast, the application of plant molecular biology that is making a major
contribution to horticulture and is not embroiled in controversy is genomics, the
use of molecular markers and a marker assisted breeding (Stephenson et al.
2010
).
Many plant genomes have now been sequenced and numerous molecular markers
have been developed for a wide range of character traits. Following an analysis
of the papaya genome sequence, all simple sequence repeats (SSR) markers have
been identified (Wang et al.
2008
). This example for papaya shows how quickly
technology is progressing and the quantum leaps that are being and will be made in
