Memorandum by the Institute of Arable
1. Both wheat and sugar beet were amongst the
last crops for which reasonably efficient transformation systems
have been developed. There are, therefore, fewer products than
might otherwise have been expected. Wheat has been transformed
by using a ballistics device (gun). This approach often leads
to larger inserts of foreign DNA than the use of Agrobacterium-based
methods. sugar beet has been transformed in different ways including
using Agrobacterium vectors. The poor efficiency of almost
all techniques has required the use of selectable markers (e.g.,
herbicide resistance) and has precluded the use of more sophisticated
techniques to remove bacterial antibiotic resistance markers.
This may change as technologies develop.
2. Modification in sugar beet are nearer the
market and include herbicide tolerance (to both Roundup from Monsanto
and Basta from AgrEvo) and virus resistance. Future targets in
sugar beet might include (if suitable genes can be defined):
Virus resistance; virus yellow is
a major economic problem.
Nematode resistance; these are major
economic pests worldwide.
Aphid resistance; because the aphids
carry viruses would have to stop the aphids from damaging the
plant sufficient to transmit the virus.
Production of sugars other than sucrose;
this could provide some industrial attraction.
drought and frost; drought is the largest single problem for the
UK beet crop.
Control of bolling/flowering; sugar
beet is a biennial and is triggered to flower by colda
barrier to beneficial early planting.
3. Modifications field-tested in wheat include
genes for controlling fungal diseases and modified processing
properties. Future modifications might include.
Herbicide tolerance; although neither
Monsanto nor AgrEvo have announced such projects in wheat. There
are technical opportunities using other herbicides if they are
Modified starch and further modifications
to seed proteins; already there are commercial plants that separate
out the starch and gluten from wheat grain, possibilities exist
to enhance the value of both products and to replace imported
Modification of height and straw
strength; lodging is still a problem and chemicals to shorten
and strengthen the straw are used widely.
Genes to allow easier production
of hybrid seed; novel genetic approaches to make hybrids in oil-seed
rape are in commercial trialsthese could eventually be
adapted to work in wheat, which would greatly enhance the value
of the seed market.
Virus resistance, particularly to
Control development; sprouting, malting
quality depend on the way seeds develop.
4. Because both crops are already tolerant to
a wide range of herbicides almost all the acreage of both crops
is sprayed with herbicides. GMO herbicide-tolerant crops will
increase the range of herbicides available. This change will allow
more environmentally friendly herbicides and even less herbicidal
ingredients to be used. The result will greatly depend on the
circumstances of the crops. Because the GMO crops have a high
degree of tolerance they will allow the farmer to wait to see
where the weed problems are before spraying rather than, in some
cases, having to reply on prophylactic pre-emergence spraying.
They also offer interesting biocontrol possibilities for reducing
damage from pests without reducing biodiversity and also reducing
total pesticide usage.
Fungal disease resistance
5. Cereals are major targets for fungicides
in Europe. Really effective disease resistance, which may not
be easy to achieve, would lead to a large decrease in the use
6. Both crops suffer from viruses. The most
serious in the long term are those that are present in the soil
and transmitted by fungie.g., Rhizomania in sugar beet.
Because infected soils are almost impossible to disinfect, growing
healthy crops on infected soils depends on in-built genetic resistance
to either the fungus, or the virus, or both. Some conventional
sources of resistance exist within the germplasm but there is
considerable potential for a novel GM approach. Some concerns
may arise over certain anti-viral approaches, where homologous
recombination events occur and give rise to new viruses.
Straw shortening and development in wheat
7. Genetic straw shortening could potentially
lead to increased yields and decrease use of synthetic chemicals.
Control of sprouting and germination could markedly increase the
quality and value of wheat and barley for breadmaking and brewing
8. The value of the wheat seed market is much
lower than that for hybrid crops, e.g., maize, sugar beet. The
low value of the seed will constrain the investment and traits
that are devoted to the crop. A hybrid seed market would allow
investors to recover the value of their investment. Without hybrid
cereals there will be a dependence on the public sector to drive
crop improvement by GM technology. This could have adverse effects
on the competitiveness of UK agriculture.
GMOs and end products
9. I have not covered very high value chemicals
(e.g., pharmaceuticals) which may only be grown on a very small
scale. Products, e.g., sugars, which are extracted and purified
from GMOs should not contain any trace of the inserted genes in
that they contain neither DNA nor protein. In contrast, modifications
in seed proteins will be carried through into the final product.
There will therefore be different issues to be considered in using
and following the products of GMOs in the food chain.
Escape into the wild
10. Wheat is not able to exist in the wild in
the UK for more than two or three years at most. It also has no
wild relatives in the UK with which it could cross. Cultivated
sugar beet rarely survives long in the wild. However, although
a biennial crop, a small proportion of the plants in the root
crop flower in the first year and, if not eradicated, can give
rise to a long-term weed beet problem. Therefore transgenes could
become established in weed beet. Wild Beta maritima is
restricted to costal margins and there is evidence that cross
pollination occurs rarely between these and cultivated beet. These
risks of transgene escape are currently being evaluated at IACR.