Spud genome helps fight blight

An international consortium of 26 research organisations, including New Zealand’s Plant & Food Research, announced in 2011 the successful sequencing of the potato genome (Solanum tuberosum).

Selection of tubers

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Mixture of tubers: DM (pink), RH (white) and an F1 hybrid (red).

Rights: Photo by Richard E. Veilleux, Virginia Polytechnic Institute and State University, Department of Horticulture.

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Potatoes: an important food source

The humble spud, a type of tuber, is the world’s fourth largest crop and the most important non-grain food source – it is critical for the world’s food supply. However, in part because of a condition called ‘inbreeding depression’, the potato has been prone to devastating pests and diseases such as the potato cyst nematode and potato blight, Phytophthora infestans, which caused the 1840s Irish potato famine.

Mapping the potato genome

The genome of the potato (or any organism) is a map of how all of its genes are put together, with each gene controlling some characteristic of the plant such as growth, development, colour, disease resistance and so on.

Mapping the potato’s genome provides valuable information about the evolution of tubers and biology of the spud, allowing researchers to overcome the problems caused by the plant’s limited genetic base. This limitation is what causes inbreeding depression (reduced fitness).

Publishing the potato genome

The potato genome research was published in the 14 July 2011 issue of the science journal Nature. This is the first sequence from a subgroup of flowering plants known as asterids.

Breeding disease-resistant spuds

As part of the genome sequencing, the team identified more than 800 disease-resistant genes, which have the potential to fight diseases. Singling out these genes and others with desirable traits (such as genes that affect yield numbers, nutritional benefit, taste, colour and so on) will make it easier, with selective marker-assisted breeding and genetic modification techniques, to develop new varieties of potato. In the past, potatoes have been slow and difficult to improve because of their complex genetics.

The work of analysing the genetic sequence and the function of various genes will take several years to complete and is the next job of the consortium.

What we hope to do in a number of years is to have genetic markers where we can in the lab say to the breeder – this is the one you really want if you're breeding for one that's good for processing for chips and crisps.