In a three-year GM research trial, scientists boosted resistance of potatoes to late blight, their most important disease, without deploying fungicides.
The findings, funded by the Biotechnology and Biological Sciences Research Council and The Gatsby Foundation, will be published in ‘Philosophical Transactions of the Royal Society B’ on 17 February.
In 2012, the third year of the trial, the potatoes experienced ideal conditions for late blight. The scientists did not inoculate any plants but waited for races circulating in the UK to blow in.
Non-transgenic Desiree plants were 100% infected by early August while all GM plants remained fully resistant to the end of the experiment. There was also a difference in yield, with tubers from each block of 16 plants weighing 6-13 kg while the non-GM tubers weighed 1.6-5 kg per block.
The trial was conducted with Desiree potatoes to address the challenge of building resistance to blight in potato varieties with popular consumer and processing characteristics.
The introduced gene, from a South American wild relative of potato, triggers the plant’s natural defence mechanisms by enabling it to recognise the pathogen. Cultivated potatoes possess around 750 resistance genes but in most varieties, late blight is able to elude them.
“Breeding from wild relatives is laborious and slow and by the time a gene is successfully introduced into a cultivated variety, the late blight pathogen may already have evolved the ability to overcome it,” said Professor Jonathan Jones from The Sainsbury Laboratory.
“With new insights into both the pathogen and its potato host, we can use GM technology to tip the evolutionary balance in favour of potatoes and against late blight.”
In northern Europe, farmers typically spray a potato crop 10-15 times, or up to 25 times in a bad year. Scientists hope to replace chemical control with genetic control, though farmers might be advised to spray even resistant varieties at the end of a season, depending on conditions.
The Sainsbury Laboratory is continuing to identify multiple blight resistance genes that will difficult for blight to simultaneously overcome. Their research will allow resistance genes to be prioritized that will be more difficult for the pathogen to evade.
In a new BBSRC-funded industrial partnership award with American company Simplot and the James Hutton Institute, the TSL researchers will continue to identify and experiment with multiple resistance genes. By combining understanding of resistance genes with knowledge of the pathogen, they hope to develop Desiree and Maris Piper varieties that can completely thwart attacks from late blight.
Notes to editors
The full reference: Elevating crop disease resistance with cloned genes. Phil. Trans. R. Soc. B 368: 20130087. http://dx.doi.org/10.1098/rstb.2013.0087
It is part of a special issue of the journal on the subject of: ‘Achieving food and environmental security: new approaches to close the gap’.
Funding: Findings in the current paper were largely funded through the £750,648 BBSRC grant BB/G02197X/1, ‘A pipeline of resistance genes to Phytophthora infestans from wild Solanum species and their accelerated isolation using Illumina sequencing methods’. They include insights into the pathogen, resistance in Solanum species and the 3-year field trial.
Security for the field trial was funded via a £46,039 supplement from the BBSRC.
The subsequent grant BB/H019820/1 ‘An enduring pipeline to identify and utilize durable late blight disease resistance in potato’ was awarded at £712,792 jointly between The Sainsbury Laboratory, the University of Dundee and Scottish Crop Research Institute. This project, which contributed to some findings in the current paper, is ongoing until April 2015.
The industrial partnership award is for £1.2million to the James Hutton Institute and The Sainsbury Laboratory (around £450,000 is awarded to TSL).
More on late blight
The total economic cost to farmers (losses and control measures) is currently up to £500 per hectare, or up to half the total cost of potato production in a bad year. UK farmers spend an average of £60 million a year controlling blight. It causes worldwide losses of about £3.5 billion.
As well being an economic cost, recurrent chemical sprays cause soil compaction from tractor journeys and CO2 emissions from diesel fuel.
Why improve Desiree and Maris Piper when a conventionally-bred variety is already available?
In the UK we produce and consume about 6 million tonnes of potatoes each year. The most popular are Maris Piper with around 15% of the market and Desiree with approximately 2%.
Production is from the traditional earlies, for example crops grown in the South West, through to the more widespread maincrop potatoes produced e.g. from Lincolnshire and up into Scotland. A range of different varieties are needed for this extended window of cropping from the first earlies planted in February to the later maincrops being harvested up until October for production and for the broad geographic spread on different soil types.
Overlaying these production needs with the consumer’s requirements for fresh market potatoes or ones that need to be processed for crisps or french fries - all of which have different cooking characteristics – means that no one variety meets our national needs. In fact around 200 different varieties are grown in GB to meet the needs of our market place.