ISIS Report 12/07/10

GM Blight-resistant Potatoes – Who Needs Them?

While researchers are wasting taxpayers’ money to create hazardous GM blight-resistant potatoes, non-GM highly blight-resistant varieties are already on the market, with low carbon impact and all-round appeal to consumers Dr Eva Novotny

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A new trial of genetically modified (GM) crops has begun in England [1].  The Sainsbury Laboratory at the John Innes Centre in Norfolk is testing a GM version of the popular Desiree potato to determine whether, as in the laboratory, the field-grown GM potato will remain resistant to late-blight disease. The challenge to develop such potatoes had already been taken up in 2007 by the German chemical giant BASF, in its Plant Science GmbH division; but their trials ended prematurely without a marketable result.  In fact, all such efforts are unnecessary, as blight-resistant non-GM potatoes already exist that are also outstanding in other respects, and further such varieties are in the pipeline.

Late blight is a serious disease of potatoes

Late blight is “ the most devastating disease of potatoes and one of the most devastating plant diseases of any crop [2, 3].”  In the UK, farmers typically spray potato crops with fungicide 10-15 times a year [4].  Much effort, therefore, has been put into means of controlling the disease.  As part of good farming practice, it is clearly advantageous to plant blight resistant varieties.

The disease can kill all the leaves of a plant within 10 days.  It was the cause of the great Potato Famine in Ireland and western Scotland in the 1840s and 1850s.  The pathogen responsible is Phytophthera infestans, notionally a fungus but actually more closely related to brown seaweeds.  Warm, humid weather favours the disease.  Leaves and stems can be infected, as can the tubers when spores are washed into the soil by heavy rain.  The disease can be carried from year to year by tubers that were infected in the previous season.  Although soil is not usually a source of the blight, it is possible for the disease to be transmitted when both mating types of the blight pathogen (see [5] GM Potatoes not Proven Safe for Release, SiS 47) are present in the soil.  In gardens, it is possible for the disease to be carried over on infected foliage in an insufficiently hot compost heap.

Unfortunately, the pathogen is evolving.  Until 1976, there was only the single mating type A1, which had various strains, all reproducing asexually.  Then mating type A2 appeared in Europe, brought from Mexico (the probable origin of the blight pathogens) on imported potatoes.  The two types were able to mate and produced new strains by sexual reproduction.  Since 2005, a highly aggressive strain A2-Blue13 has developed; causing blight in some potato varieties that were previously resistant, and it has become the dominant strain in the UK.  There is always the danger that the pathogen will evolve into a new strain that can overcome the resistance of potato varieties now free of the disease, and development of new varieties needs to take place on a continuing basis.

New trial by the Sainsbury Laboratory

The Sainsbury Laboratory at the John Innes Centre in Norfolk, England has received approval for field trials of GM blight-resistant potatoes, beginning in 2010.  The Laboratory claims that existing non-GM blight-resistant potatoes suffer from “other deficiencies”, but this claim cannot justly be applied to Sárpo potatoes, described later.

Natural resistance to blight occurs in some wild, inedible potato species in South America.  Two genes isolated from these have been transferred to a potato variety popular in Britain, Desiree [4, 5], and will undergo field trials for three years.

Justifying the use of genetic engineering to produce the new potatoes, the Laboratory claims that [4]: “Potato breeding is extremely slow and inefficient. … Breeding is not an exact science and changes many genes that affect important agronomic traits such as yield, quality and maturity time.  By using GM we can be sure that only the desired resistance gene is introduced into the resulting variety, without changing other characteristics.” This disingenuous statement is actually false: it is well known that the random insertion process of genetic engineering leads to disruption and rearrangement in the host’s own genome, causing ‘insertion mutagenesis’ in many genes with totally unpredictable effects (see review in [6] The Case for A GM-Free Sustainable World, Independent Science Panel, ISIS publication).

The GM potato also has an antibiotic resistance marker gene nptII that confers resistance to kanamycin and neomycin [7].  The Laboratory claims erroneously that the antibiotic is not used for medical treatment of either humans or animals.  The Advisory Committee on Releases to the Environment (ACRE) gave an approving opinion for the trials, on grounds that [7]: “(a) the likelihood of transfer of a functional gene from plant material tobacteria is extremely low; (b) bacteria with resistance to these antibiotics arewidespread in the environment; and (c) the acquisition of an intact gene isonly one of the possible mechanisms by which bacteria may developresistance.”  This is essentially the same opinion delivered by the pro-GM European Food Safety Authority (EFSA) when it examined the use of antibiotic resistance genes in food crops. On that occasion, however, two senior scientists on the panel disagreed and issued a minority opinion in an annex to the statement, saying it was not possible to assess any adverse effects and that the probability that the gene could transfer from the GM plants to environmental bacteria was between ‘unlikely’ and ‘high’ (see [8] GM DNA Does Jump Species, SiS 47).

The Norfolk trials are funded entirely by UK taxpayers, through the Biotechnology and Biological Sciences Research Council (BBSRC) [4].  This is unfortunate and a waste of taxpayers’ money, as even a Monsanto representative acknowledged that “ultimately [non-GM] biotech offers the greatest potential” for developing crops with such complex traits [9]. 

Another questionable aspect of the trials, and indeed of the whole project, is that the parent variety Desiree is already widely planted.  Thus, a newly invading disease affecting the GM potato may wipe out a major portion of the UK’s potato harvest, both GM and non-GM.

In fact, GM potatoes for late-blight resistance had already been trialled and abandoned by another corporation.  German chemical company BASF had produced GM blight-resistant potatoes.  Field trials were started in 2007, originally planned for the Irish Republic but moved to England after the Irish authorities placed very high requirements on the conduct of the trials, especially the requirement for safety testing by feeding the potatoes to animals prior to commencement of  trials. 

A site at Hedon, near Hull, was then chosen but was cancelled when the hosting farmer realised the damage that would result from GM contamination of nearby borage farms, valuable to bees.  Trials did, however, proceed at the National Institute of Agricultural Botany (NIAB) in Cambridge, despite protest from local residents.

A geneticist commented on these trials [10]:

“The risk assessment has been granted using the assumption that these are normal potatoes with a few predictable genes added. A characteristic feature of transgenic crops is that they do not behave in such a predictable fashion. The reason BASF is testing so many transgenic lines is precisely because transgenics are not predictable ... the documents show an astonishing reliance on assumption-based reasoning.”

Five years of trials were planned at NIAB, but only two years, 2007 and 2008, were completed; after that, the Cambridge trials were discontinued.  The reason given was the delays in EU approval for GM potatoes: another variety they were testing elsewhere, Amflora, which produces an industrial starch, had still not received approval at the time the Cambridge trials were aborted [11].  Now that the EU has at last given approval for the cultivation of Amflora [12], BASF may be encouraged to resume research in this direction.

Non-GM blight-resistant potatoes

The GM industry has been claiming that non-GM blight-resistant Sárpo potatoes are not liked by consumers because they do not taste good and do not boil up well.  These allegations were put to the test in London in March, 2010.  A tasting event was organised at the Konstam Restaurant at the Prince Albert in London, where the chef prepared Sárpo potatoes in various ways.  Invitations had been issued to various groups and individuals, including supermarkets (with one positive response) and the media (with one positive response).  Four varieties were made available for the event: Sárpo Mira, Sárpo Axona, Sárpo Una and Blue Danube.  Their properties differ and, as with the common varieties of potato, some are better suited than others for particular methods of cooking.  One variety that indeed does not boil well nevertheless proved its worth in the tasting event: it made a delicious soup and also a tempting puree served on small biscuits.  Other Sárpos were made into chips, fries and jacket potatoes.  They were unanimously acclaimed by the participants to be very tasty and deserving of widespread adoption.  The representative of a major supermarket who took part declared that she would urge her company to market Sárpos.

Six varieties are now on the UK National List of seeds given approval for commercial sale: Sárpo Axona and Sárpo Mira were the first to be registered, followed in June 2009 by four more.  All of these are described by the Sárvari Research Trust, and more are on the way [13].

“Sárpo Mira and Axona are both high yielding, red-skinned, main crop varieties with high dry matter.  Sárpo Mira makes attractive chips (French fries) and Axona makes excellent flavoured mash.

“Sárpo Una has good foliage-blight resistance for an early variety and excellent tuber resistance.  Tubers are rose-pink with a good skin finish.  Flesh is white in colour and low in dry matter making it useful for boiling, gratin and as a salad.  Trials have found good resistance to powdery scab, potato virus Yo, dry rot (F. sulphureum), black dot, silver scurf and skin spot.

“Sárpo Shona is a blight resistant and virus Yo resistant, white-skinned variety with early-maincrop maturity.  The short foliage is dense and weed-smothering.  Tubers are short oval and can be prepared in most ways due to their medium dry matter content.  Independent Variety Trials show tubers to have good resistance to black dot and black scurf.

“Kifli is a long, white-skinned variety with outstanding flavour when prepared as a freshly harvested, loose-skinned potato.  Plants show medium resistance to late-blight and high resistance to virus Yo.  It has good resistance to splitting and bruising, to blackleg and to PCN Ro1 [potato cyst nematode].

“Blue Danube has purple-black stems, shiny dark foliage and spectacular blue-skinned tubers of good shape and skin finish.  It is an early maincrop with medium foliage-blight resistance and good tuber-blight resistance.  It has good resistance to virus Yo and to leafroll virus, blackleg, dry rot (F. coeruleum) and PCN Ro1.  The flesh is white  and of medium dry matter content.  Growers experimenting with this variety always want more – it is developing cult-status.”

Thompson & Morgan, “Experts in the garden since 1885”, sell three varieties of Sárpo potatoes, and describe them very favourably [14].

At the tasting event in London, Dr David Shaw, Director of Research at the Sárvári  Research Trust, said that farmers’ markets and the Prince of Wales’ estate, Highgrove, “love them”.  They are popular in the Duchy box-scheme.   “Glowing reports” come from Ireland; and Wales and Scotland are also becoming interested in Sárpos.

Environmental benefits of Sárpo potatoes

Not only are Sárpo potatoes a boon to farmers for their disease resistance but they offer additional benefits, which importantly include a light carbon-footprint [15].  With natural resistance to viruses, they rarely require spraying for virus-transmitting aphids.  Their abundant foliage smothers weeds, unless weed infestation is high; hence spraying of herbicides is not necessary.  No spraying against blight is needed, even in wet seasons such as 2007, when other normally resistant varieties succumbed.  The best Sárpos are resistant to all known strains of blight. Sárpos can be grown in poor soils with a minimum of added nutrients.  Storage even into late spring requires no refrigeration because of their long dormancy, nor do they need application of a sprout-inhibitor.  In addition, some varieties have excellent drought tolerance.

The lack of chemical use on Sárpos contrasts with the heavy use on other potatoes, which need chemical sprays every 5-7 days or, in a bad season, every 3 days.  Even organic farmers may be forced to apply chemicals, based on copper; however, these are poisonous and will be phased out in EU countries.

Sárpo potatoes can undoubtedly be grown also outside Europe, particularly in developing countries where chemical controls for blight are unaffordable.

History of Sárpos

Breeding of the non-GM potatoes began in Hungary during the days of the Soviet Union [16].  They were intended for cultivation throughout that bloc; and a hardy strain, resistant to harsh climate and disease, was required.  Research was undertaken at the Keszthely Institute, which later became the Potato Research Centre at the Pannonia Georgikon Faculty of Agriculture.  The Director was Dr Istvaán Sárvári, who was joined in the work by his wife; and the family name has been given to Sárpo potatoes as a combination of Sárvári and potato. 

To develop the high degree of resistance required, wild potatoes from South America and Mexico were used in the breeding programme to confer resistance to common viruses.  Later, high resistance to late blight was added.  In 1994, a Scottish potato seed grower, Adam Anderson, came upon a potato trial in Romania.  The potatoes had been devastated by blight except for certain plants, which Anderson traced to the Sárvári family.  Anderson and others then formed a company to help support the breeding programme and built a research station near the Sárvári family home.  Work has continued after the death of Dr Sárvári by his wife and two sons.

The Sárvári Research Trust was formed in Wales as a not-for-profit organisation in 2002.  When a promising variety is developed in Hungary, it is sent to Wales for further testing and commercialisation.  To expose the potatoes to as many different strains of the pathogen as possible, trials are carried out at many places in the United Kingdom, several European countries and Mexico.  In addition to late-blight resistance, new candidates are tested for “yield; tuber number, shape and uniformity; resistance to other pests and diseases; foliage maturity and dormancy; cooking and processing quality and taste”.  Continuing research is necessary to keep pace with evolving new strains of blight.

Why we don’t need GM potatoes 

Development of a GM crop takes years of research and trials, and it is an extremely costly process that includes taxpayer funding. Many hazards to health and the environment are incurred once the crop is approved for commercialization, and even during field trials.  Evaluation of these hazards by the UK government and by the EU is lax, relying on data supplied by the seed company while dismissing the warnings of independent scientists whose own trials show harm [8].  In contrast, Sárpo potatoes, already on the market and with more to follow, have all-round excellent characteristics including a low carbon-footprint.  They provide much more value, at far lower cost than those on trial at the Sainsbury Laboratory. So why do we need GM potatoes at all? 

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