Breakthrough in potato genome
Scientists at Teagasc Oak Park, Co Carlow, and their partners in the inter-national potato genome sequencing consortium (PGSC) have published the world’s first high-quality draft sequence of the potato genome in the journal Nature.
Knowledge of the genetic blueprint will reduce the 10-12 years currently needed to breed new varieties of potato, the world’s third most important food crop after wheat and rice. With the Teagasc team already enjoying success in tackling potato blight and diseases, the longer term implications in battling world hunger could be very significant.
Teagasc group leader Dr Dan Milbourne, said: “Having the genome sequence will supercharge our ability to produce new types of potato. This really speeds up the process. It allows us to test for disease resistance about five years earlier.
“We are already using this in our potato breeding programme, developing resistance to blight and diseases caused by nematode worms. Previously, it took five years of development work to get to that stage.”
By 2020, more than two billion people worldwide are expected to depend on the potato.
Dr Milbourne said: “All breeding is essentially taking pairs of potato plants with complementary traits and crossing them with each other. You are trying to produce progeny combining the best of these traits. One of these traits is disease resistance, and this is the main focus of the drive to exploit the genome sequence at Teagasc.
“We have developed genetic fingerprinting tests which tag disease resistance genes — called ‘R’ genes — which already exist in one or other of the parents. For predictive purposes, you can take DNA of the progeny and look to see which ones have the ‘R’-genes from the parents. Using this approach we can identify resistant plants several years earlier than previously. Unlike GM, you are tracking genes which are already there.”
Dr Milbourne and his colleagues at the Crops, Environment and Land Use Research programme at Oak Park are also hoping to use this research to enhance the potatoes’ nutrients and production efficiencies. This work will also be useful in managing climate change and cutting carbon costs.
Teagasc potato breeder Dr Denis Griffin said:“The capacity to combine cutting edge genetic fingerprinting technologies with our expertise in traditional breeding methods will contribute significantly to our continued success in developing high-quality potato varieties for both Irish and international markets.”
The Oak Park team was one of the earliest members of the PGSC project, initiated in January 2006 by the Plant Breeding Department of Wageningen UR in the Netherlands, which has developed into a global consortium of 29 research groups from 14 countries.
The Teagasc group contributed directly to the whole genome sequencing effort, and also performed an in-depth analysis of a region on ‘chromosome 4’, which harbours genes that confer natural resistance to late blight and the potato cyst nematode, the two most significant limitations to potato production.
The group also gained insights into the biology and evolution of potato; significantly how expan-sion of particular gene families has contributed to the evolution of the potato tuber — the edible storage organ that is the most striking feature of this important crop plant.
In late 2009, the consortium released a preliminary draft sequence of the potato genome online. Since that time the consortium has been refining the genome assembly, as well as performing exhaustive analysis and interpretation of the data.
The genome assembly covers approximately 95% of the genes in potato, and was facilitated by radical advances in DNA sequencing technology that have occurred over the past few years, and new software developed by the Beijing Genomics Institute, one of the Chinese partners in the PGSC.
Analysis of the genome sequence data has revealed that the potato contains approximately 39,000 protein coding genes. For over 90% of the genes, the location on one of the potato’s 12 chromosomes is now known.
For more on the potato genome assembly and other resources, see: www.potatogenome.net, which also has a complete listing and contact details for all PGSC members.
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