Algae belonging to two groups, the Chysophyceae and Dinophyceae, are
the main culprits for algal blooms in the Adriatic and North Seas. A team
from the university’s Institute of Plant Physiology, led by Werner Reisser,
has already isolated and identified viruses capable of killing strains of
freshwater Chlorella algae. They intend to use this information as a model
system for other virus-algae interactions. ‘We are routinely checking marine
algae for viruses,’ Reisser explained.

According to Reisser, the viruses that infect Chlorella attach to specific
sites on the cell wall of the algae. Reisser thinks the virus breaks into
the algae by releasing enzymes which digest the carbohydrates in the cell
wall. Then, by some unknown mechanism, the virus DNA penetrates the interior
of the algal cell and hijacks its genetic machinery for reproduction. As
the viruses multiply, the cell eventually breaks open, releasing the viruses
to infect other cells.

Reisser and his colleagues have isolated viruses capable of killing
some species of Chlorella. Under laboratory conditions, the Gottingen group
has been able to use these viruses to infect other samples of Chlorella.

The prospect of genetically modifying a virus in order to enhance the
killing of algae is still a long way off, however. It is also unlikely that
any authority would want to take the risk of releasing such a modified virus
into the environment.

With support from the government-funded German Research Organisation,
the Gottingen team is trying to understand how the virus infects plant cells,
in particular those physical conditions under which the virus is most harmful
to the algae. ‘We need to know more about plant viruses other than Chlorella
viruses, which could simply be a special case,’ says Reisser. ‘So far, there
are only a few reports on viruses in algal systems and only one system (the
Chlorella virus system) can be handled in the laboratory.’

Reisser believes this approach could also provide opportunities to kill
toxic algae and cyanobacteria (blue-green algae) in drinking water and in
fish farms. In the longer term, he sees the potential to control the growth
of large-scale marine algal blooms such as those seen in the Adriatic and
North Seas.

This gesture is applauded by John Whitcombe, associate manager of the
Overseas Development Administration’s plant sciences programme. AGC waiving
its rights means that anyone will be able to use the sweet potato technology.

The sweet potato’s susceptibility to insect damage can slash yields
up to 80 per cent. With 98 per cent of the world’s sweet potato crop grown
in the developing regions and consumed locally, the key beneficiaries of
the modified potatoes will be the farmers and consumers of the developing
world. The growers will benefit from increased yields, lower input costs
(in terms of labour, insecticides and equipment) and increased productivity
and profitability.

With funds from the ODA, scientists at AGC, the University of Durham,
and the International Potato Centre (CIP) in Lima, will attempt to incorporate
AGC’s insect resistance gene, the cowpea trypsin inhibitor (CpTI) into the
sweet potato. The gene prevents the breakdown of certain proteins in the
digestive system of insects so that insect larvae are deprived of essential
nutrients and die.

‘The research .. will contribute to overcoming the effects of sweet
potato weevil which has become an insurmountable problem to control with
conventional approaches,’ says the company.

Chemical control of sweet potato pests has had varying degrees of success,
with many chemicals being too expensive. And conventional plant breeding
has not been successful in producing high-yielding insect-resistant crops.

Champions of the rights of developing nations welcomed AGC’s offer with
the caveat that the patent system still favours the rights of richer nations
and penalises poor nations. David Cooper of Genetic Resources Action International,
based in Barcelona, pointed out that it was farmers in West Africa who first
noted the resistance of some varieties of cowpea to insects and who nutured
superior varieties that carried this characteristic.

‘Decisions about who has access to the gene should not be in private
hands in the first place,’ he said. ‘We are worried about patent law restricting
access to the gene itself, because the resource existed before.’