Scientists breed tougher potatoes •

The potato is increasingly incorporated into regular diets around the world, even in Asian countries where rice has been the traditional staple food for millennia. However, unlike the case of other major staple crops such as rice or wheat, efforts to breed new potato varieties with higher yields have remained unsuccessful.

A research team led by the Max Planck Institute for Plant Breeding Research tries to solve this problem by implementing genome-assisted selection of new potato varieties that will be more productive and resistant to climate change.

After buying potatoes in a market today, it is quite possible that the buyer will come home with a variety of potato that was already available a century ago. This not only speaks to the enduring popularity of traditional potato varieties, but also highlights their lack of genetic variety. This can have dramatic consequences, such as the Irish famine of the 1840s, where for several years the only existing variety of potato crop was attacked by newly emerging tuber blight and rotted in the ground.

The difficulty in selecting different varieties of potatoes comes from the genetic particularity of this plant. Instead of inheriting one copy of each chromosome from both father and mother (like humans do), potatoes inherit two copies of each chromosome from each parent, making them a tetraploid species.

This increased genetic complexity makes it very difficult and time-consuming to create new varieties with the desired combinations of individual properties. Moreover, the multiple copies of each chromosome also make the scientific reconstruction of the potato genome a very difficult task.

Scientists at the Max Planck Institute have successfully overcome these long-standing problems and managed to generate the first complete assembly of the potato genome with a simple and elegant trick. Rather than trying to tell the four – often very similar – chromosomal copies apart from each other, the researchers sequenced the DNA of large numbers of individual pollen cells, which only contain two random copies of each chromosome. This helped them reduce the complexity of the problem and finally sequence the entire potato genome.

With this information, researchers can now more easily identify genetic variants responsible for desirable or undesirable traits, and incorporate or exclude them during breeding. Improved potato breeding could have a huge impact on food security in the decades to come.

By Andrei Ionescu, Personal editor