Potato Genome Sequence Released by International Group of Scientists

The Potato Genome Sequencing Consortium (PGSC), an international team of researchers, including scientists from Teagasc, has announced that it has released the first draft sequence of the potato genome.

Potato, a key member of the Solanaceae family, is a close relative of tomato, pepper, and eggplant. It is the world's third most important crop and the most important vegetable crop. Access to the potato genome sequence, the “genetic blueprint” of how a potato plant grows and reproduces, is anticipated to assist scientists in improving yield, quality, nutritional value and disease resistance of potato varieties. More importantly, the potato genome sequence will permit potato breeders to reduce the 10-12 years currently needed to breed new varieties.

The PGSC was initiated in January 2006 by the Plant Breeding Department of Wageningen University and Research in the Netherlands and has developed into a global consortium of research groups from 14 countries. Teagasc’s contribution to the project was carried out at Crops Research Centre, Oak Park, Carlow, where the PGSC met earlier this year to plan the release of the draft genome. Oak Park Research Centre is also the home of Teagasc’s highly successful potato breeding programme, which has produced well known varieties such as Rooster and Cara.

“Potato has tens of thousands of genes” said Oak Park project leader Dr Dan Milbourne “and the draft sequence will allow us to identify about 95% of them. This will revolutionise both our understanding of the biology of potato and our ability to breed better potato varieties.” The earliest results from the potato genome sequence have already had a positive impact on the potato breeding programme at Oak Park, where Milbourne and potato breeder Dr Denis Griffin have used the results to develop genetic fingerprinting tests to identify potential varieties with natural resistance to pests and diseases such as potato cyst nematodes and late blight.

“Research such as this is incredibly important to the future competitiveness of Irish agriculture and puts Teagasc at the forefront of exciting developments in science,” said Professor Jimmy Burke, head of Teagasc Crops Research Centre and leader of the plant biotechnology programme. He said; “combining our expertise in plant breeding with cutting-edge biotechnology-based research is enhancing our ability to develop plant varieties suitable for Irish conditions and agricultural practices. We are pursuing similar projects in other species important to agriculture here in Ireland, including perennial ryegrass, white clover and wheat, and energy crops, and we expect similar successes in these species in the future”.

This first draft of the potato genome sequence is now available in the public domain at www.potatogenome.net and updates will be made over the next six months as additional data is generated including annotation of the genes, analysis of when and where they are switched on and off, and analysis of specific suites of genes that are critical to potato production.

A complete listing as well as contact details for all PGSC members can be found at www.potatogenome.net

The potato genome

Every organism has a genome, a chemical 'instruction book' or 'blueprint' that describes how all the genes should be put together. This is written down as a DNA sequence, a long sentence made up of the chemical letters (nucleotides) A, C, T and G. This sequence contains many tens of thousands of genes which can be thought of as 'words' in the sentence. Each gene controls different aspects of how the organism grows and develops. Slight changes in these instructions give rise to different varieties - each individual has a slightly different version of the DNA sequence for the species. Understanding the complete genome sequence, the exact spelling of the DNA letters, for potato will help scientists develop a better understanding of how potato grows and develops, leading to improved crops worldwide. Each copy of the potato genome consists of 12 chromosomes and has a length of approximately 840 million nucleotides, making it a medium-sized plant genome. A high quality, well-annotated genome sequence of potato will provide a valuable foundation which can be combined with existing knowledge of potato genetics and the continuing advances in analysing which genes are switched on or off and which chemicals are produced when and where. Observing how these changes are affected by changes in the genome will allow scientists to identify different variants of genes which are responsible for important quantitative traits in potato. The Potato Genome Sequencing Consortium (PGSC) seeks to provide such a resource to the potato research and breeding community in the near future, allowing the full potential of biotechnology-based improvement of this important crop plant to be realised. The Potato Genome Sequencing Consortium aims to deduce the complete genome sequence for potato by the year 2010.

About potato

Potato is a member of the Solanaceae, a plant family that includes several other economically important species, such as tomato, eggplant (aubergine), petunia, tobacco and pepper. Potato is an important global food source. After wheat and rice, potato is the third most important food crop, with a world-wide production of 309 million tonnes in 2007. By 2020, it is estimated that more than two billion people worldwide will depend on potato for food, feed, or income. Improving potato varieties so that they can better cope with environmental challenges such as drought, and pests or diseases are key objectives of global potato breeding programmes.

The potato has one of the broadest genetic diversities of any cultivated plant. Wild species of potato are very widely distributed in the Americas, from the South Western US to Southern Chile and Argentina and from sea level to the highlands of the Andes Mountains. Many wild species can interbreed directly with the common potato and possess a wide range of valuable traits such as resistance to pests and diseases or tolerance to frost and drought, making them a useful resource for breeding new varieties.

Worldwide, an economic loss on the potato crop of about €3 billion per year is estimated from diseases such as late blight. These diseases are still largely controlled by frequent application of fungicides. It is expected that one of the first benefits of knowing the potato genome sequence will be a major breakthrough in our ability to characterise and select genes involved in disease resistance.

However, potato, unlike man, has four, slightly different, copies of the genome (it is polyploid). It gets two copies of its genome sequence from the mother plant, and a separate and slightly different set of two out of four from the father. This makes analysis rather complicated. Therefore we are working with a potato which, like human, has two copies of the genome. It gets one copy of the genome from one parent, and one copy from the other parent. These are slightly different, and different combinations of these differences are responsible for the differences we see between potato varieties, just as people differ from one another and from their parents. This makes studying potato genetics complicated and many important traits are poorly understood. Yet, an understanding of its genetic composition is a basic requirement for developing more efficient breeding methods. The potato genome sequence will provide a major boost to gaining a better understanding of how potato traits are linked to genes, underpinning future breeding efforts. Currently potato breeding takes about 10-12 years to develop a new variety. It is expected that being able to use the genome information will dramatically shorten the time taken to breed new varieties as well as reducing the cost.

Potato Genome Sequencing Consortium

The international Potato Genome Sequencing Consortium (PGSC) is a collaboration between 16 research groups in 14 countries; Argentina, Brazil, China, Chile, India, Ireland, Italy, the Netherlands, New Zealand, Peru, Poland, Russia, the UK and the US. The PGSC has its basis in long-standing research on the molecular genetics of potato within the partner organisations, and includes partners with world-leading expertise in genome sequencing and computational analysis.