The full weight of a consortium of world-leading scientists -
including those who helped decode the entire human genome - is being thrown
at a parasitic worm less than 1mm long.The potato cyst nematode (PCN),
Globodera pallida, attacks potato crops all over the world and is
particularly devastating in developing countries where the potato is a
subsistence crop.
A ?1.7 million project led by the University of Leeds to fully
sequence its DNA, hopes to shed light on the mechanisms that make the tiny
worm such a successful parasite - and lead to methods to sustainably manage
this pest.

The research, funded by the Biotechnology and Biological Sciences
Research Council (BBSRC), draws together experts from the University of
Leeds, the Wellcome Trust Sanger Institute, Rothamsted Research and SCRI,
Scotland's leading centre for crop research.

"Although there is partial resistance in some potato varieties, it is
very difficult to breed this resistance into commercial ones - so we're
tackling the problem from a different perspective," says Dr Peter Urwin from
Leeds' Faculty of Biological Sciences. "If we can find out exactly how this
worm works so efficiently, it should lead to measures that will help the
potato plant to withstand attack."

The worm invades the roots of the potato plant and injects a substance
causing the plant to create a unique cell from which it feeds via a
specialised tube. By doing this, the nematode stunts root growth and
deprives the potato plant of essential nutrients, which leads to lower
quality, smaller crops.

Says Dr Urwin: "This tiny parasite has evolved many clever mechanisms
that we hope to be able to understand more fully through this research. We
have no idea what this injected substance is or how it manages to persuade
the plant to create the feeding cell. In addition, its eggs can remain
viable in the soil for up to twenty years, with hatching triggered by
sensing chemicals released by potato roots nearby. Because of this, once a
field is infected, it's almost impossible to get rid of them."

G. pallida is an international problem, affecting the world's two
major potato growing regions - the Ukraine and Idaho, USA - as well as 18
countries in the EU and 55 countries world wide. The widespread cultivation
of potato varieties such as Maris Piper, which whilst naturally resistant to
other PCNs, are not resistant to G. pallida, suggests that the significance
of the worm is likely to increase.

UK farmers spend in excess of ?50 million a year in efforts to manage
the pest. Infestations are currently treated with toxic chemicals, which do
not enter the food chain, but are expensive to apply and can make soil
sterile, killing other living organisms within it.

Dr Urwin says that controlling G. pallida is essential to maintain the
competitiveness of UK potato industry, which together with processing and
retail markets is worth some ?3 billion per year. "We think that consumers
are more likely to support UK production that avoids pesticide residues and
environmental harm and that is soundly based on a sustainable approach," he
says.

The team hope to complete the sequencing by 2012.

Source: adapted from materials provided by University of Leeds.
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