Searching for the resistant potato

Searching for the resistant potato

Potatoes are y far the most pesticide-intensive crop grown in Denmark. Genome-modification would quickly decrease the demand for pesticide drastically, but legislation prevents it from happening. Instead, Professor Kåre Lehmann Nielsen and his colleagues are developing algorithms that makes it possible to breed more resistant potatoes.

The sensitive potato

One of the world’s most common starch-crops – the potato – is a demand and sensitive crop. Because potatoes are grown using seed potatoes, potatoes are practically each other’s clones, and diseases have had ample time and possibility to adapt to the crop. This means that potatoes are extremely susceptible to potato fungi, that has been the arch enemy of potatoes since the 1860ies.

Among other things, this makes ecological potato farming troublesome. In Denmark, it is practically only possible to grow the earliest sorts that can be harvested in the spring before the fungi attacks begin – without the use of fungicides. Larger, starchy potatoes that spend longer time underground, have a high demand for pesticides to overcome the fungi. Even though potatoes only take up about around two per cent of the Danish agricultural area, 14 per cent of the total amount of pesticides are used on them.

- The problem with potatoes is that we use many of the same sorts, or sorts that are very similar to the ones we used 150 years ago. Genetically, they are nearly identical and thus, they are easy targets for fungi that have also had 150 years to target their attacks on all the most commonly used sorts, explains Professor Kåre Lehmann from the department of Chemistry and Bio Science.

GMO can make pesticides redundant – but aren’t allowed

With today’s knowledge about genetics and gene modification tools like CRISPR, scientist would quickly and relatively easy be able to make popular and well-known potato sorts resistant against potato fungi. However, the EU GMO directive makes it difficult and very unattractive to grow genetically modified crops in Europe. This is a shame, says Kåre Lehmann Nielsen, who estimates that up to 90 percent of today’s pesticides used on potatoes could be made redundant by tweaking minor element of the well-known potatoes’ genetic code.

Thus, the solution to the sensitive potatoes has to be found using a somewhat slower method. In order to develop a sustainable and resistant potato that can be farmed legally, it has to be bred and developed the old-fashioned way by crossing different sorts of potato plants to foster the right properties.

This is a very time-consuming labour. Therefore, Kåre Lehmann Nielsen and his colleagues have developed a series of algorithms to make resistant potato-breeding faster and easier.

- When you ennoble and cross different sorts, your success rate may be one in a thousand. You may quickly be able to produce a potato with a high degree of resistance, but you may not achieve the same taste, colour, yield or growth rate that you were hoping for. By using mathematical algorithms we can skip some of the most useless combinations of plants and speed up the whole process. This means that we can develop a wide variety of sustainable sorts within a number of years, he says.