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Preface to a Special Issue on Late Blight
and Genetic Modification
Paul C. Struik
Published online: 28 June 2008
# EAPR 2008
The 51st volume of Potato Research starts with a special issue on Late Blight and
Genetic Modification. It is a very special issue indeed as it brings together papers
from very different disciplines, some only rarely represented in Potato Research.
Late blight, caused by the oomycete Phytophthora infestans, is worldwide the
most devastating disease in the potato crop. Agronomic control of the disease
requires a large management effort, including a crop rotation excluding alternative
hosts, elimination of potential sources of the pathogen (including the use of healthy
seed tubers, eliminating piles of cull potatoes, eliminating ground keepers and
volunteer potatoes), monitoring weather, disease monitoring in the field and effective
action once an outbreak is to be expected. In organic farming in NW Europe the
disease seriously affects the profitability of the crop as there are no effective tools to
control an outbreak except the environmentally harmful copper-based Bordeaux
mixture or killing off the haulm before a certain threshold of infestation is reached.
In conventional farming an infestation can be prevented or cured by applying
fungicides. However, fungicide costs can be a large proportion of the total value of
the crop. Societal costs other than loss of value or increases of production costs are
also considerable.
Breeding for resistance against late blight has not been very successful. All major
resistance genes from Solanum demissum which were introgressed into the cultivated
potato to create resistance were overcome by development of virulence genes by the
disease. Pyramiding minor resistance genes has not proven to be possible or fruitful.
Genetic modification has great potential to contribute to effective breeding for
resistance but certain groups in society have difficulty in accepting that approach. In
order to make genetic modification more acceptable scientists have designed
breeding techniques based on cisgenesis. Cisgenesis is a genetic modification
P. C. Struik Crop and Weed Ecology, Wageningen University, P.O. Box 430, 6700 AK Wageningen,
The Netherlands
e-mail: ****.******@***.**
Potato Research (2008) 51:1 3
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technique only using gene sequences from the species itself or from closely related
crossable species. This means that a cisgenic plant does not contain genes from other
non-crossable species and suggests that cisgenic plants contain combinations of
innate genetic material that could also occur in nature. Scientists therefore claim that
cisgenesis has the advantage over classical methods of breeding in that it is quick
and efficient and that genes for resistance against late blight can be stacked and
introduced into the plant in one step without linkage drag problems, i.e. without
inserting deleterious genes together with beneficial genes.
However, the debates about moral aspects of cisgenesis and about whether
cisgenic crops can be exempted from the strict legislative regulations and oversight
for transgenic crops have not been completed. These debates are especially relevant
in the case of introducing late blight resistance to potato by cisgenesis as history has
taught us how devastating this disease is and how little progress we have made in
solving the problem in a sustainable way.
This special issue starts with a contribution by Zadoks. Zadoks tells us the story
of the Continental Famine of 1845 1847 which coincided with the Irish Famine of
1845 1849. This Continental Famine is much less known but not only claimed
many lives but also contributed to the series of social revolutions that broke out on
the European Continent in 1848 and which changed the world.
The next paper in this special issue is by Haverkort et al. who describe in great
detail the societal costs of late blight. These costs justify additional investments in an
innovative research approach based on detection of R-genes, assessment of their
function in the infection route and reproduction of the pathogen, cloning of these
R-genes and inserting them into existing varieties, spatial and temporal management
of resistance and close communication and interaction with all relevant stakeholders.
After the scene has been set and the need for alternative approaches has been
clarified, Jochemsen provides a detailed ethical assessment of cisgenesis and
concludes that there is indeed a significant ethical difference between transgenesis
and cisgenesis but that any form of genetic modification requires proper integration
in a broader, normative understanding of agriculture.
Jacobsen and Schouten provide their views on the use of the novel molecular
technique of cisgenesis. They argue that cisgenesis should be exempted from the
regulation on genetically modified organisms in a step by step approach as
cisgenesis is actually a new tool for traditional breeding and the ecological risks of
the products of cisgenesis are absent or very minor. They stress that cisgenesis could
greatly contribute to a durable solution for late blight in potato, both in conventional
and organic agriculture.
Finally, Lammerts van Bueren et al. explain why cisgenesis is incompatible with
the organic movement s perception of environmental risks, its view on the right of
farmers and consumers to make a free choice, and with the biological principles of
sustainability of that movement. The organic movement cannot accept cisgenesis as
a solution for a problem that indeed is threatening the existence of organic potato
production but prefers to go the long, and in its view more sustainable, route of
organic breeding using participatory, traditional approaches but innovative breeding
material.
Potato Research (2008) 51:1 3 3
I hope that this special issue provides interesting and pleasant reading and
contributes to a better understanding of the different views on late blight and genetic
modification.
This special issue on Late Blight and Genetic Modification is part of the
dissemination activities carried out by the EAPR within the BIOEXPLOIT project.
This project is supported by the European Commission through the 6th framework
programme. Contract number: FOOD-CT-200*-******.
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