Complete sequencing of genetic material facilitates the breeding of new varieties — ScienceDaily

More than 20 years after the first release of the human genome, scientists from the Ludwig-Maximilians-Universität München and the Max Planck Institute for Plant Breeding Research in Cologne have decoded the highly complex potato genome for the first time. This technically demanding study lays the biotechnological foundation for accelerating the breeding of hardier varieties – a goal in plant breeding for many years and an important step for global food security.

When buying potatoes at a market today, buyers may well come home to a variety that was already available over 100 years ago. Traditional potato varieties are popular. And yet, this example also highlights a lack of diversity among the predominant potato varieties. However, that could soon change: researchers from the group of geneticist Korbinian Schneeberger have been able to generate the first complete assembly of a potato genome. This paves the way for breeding new hardy varieties:

“The potato is increasingly becoming an integral part of diets around the world, including even Asian countries like China, where rice is the traditional staple food. Building on this work, we can now implement genome-assisted breeding of new potato varieties that will be more productive and also resilient to climate change – this could have a huge impact on food security in decades to come. future. »

In particular, low diversity makes potato plants susceptible to disease. This can have dramatic consequences, most dramatic during the Irish famine of the 1840s, when for several years almost the entire potato crop rotted in the ground, and millions of people in Europe suffered starvation simply because the only variety grown was not resistant. to the newly appeared tuber blight. During the green revolution of the 1950s and 1960s, scientists and plant breeders managed to dramatically increase the yields of many of our major staple crops like rice or wheat. However, the potato did not experience a comparable boom, and efforts to create new varieties with higher yields remained largely unsuccessful until today.

The reason for this is simple but has proven difficult to tackle – instead of inheriting one copy of each chromosome from both father and mother (as in humans), potatoes inherit two copies of each chromosome from each parent, making it a species. with four copies of each chromosome (tetraploid). Four copies of each chromosome also means four copies of each gene, which makes it very difficult and time-consuming to create new varieties that harbor a desired combination of individual properties; Moreover, the multiple copies of each chromosome also make reconstructing the potato genome a much more difficult technical challenge than was the case for the human genome.

The researchers overcame this long-standing obstacle using a simple but elegant trick. Instead of trying to differentiate between the four, often very similar, chromosomal copies, Korbinian Schneeberger, along with his colleague Hequan Sun and other colleagues, circumvented this problem by sequencing the DNA of large numbers of individual pollen cells. Unlike all other cells, each pollen cell contains only two random copies of each chromosome; this facilitated the reconstruction of the whole genome sequence.

An overview of the complete DNA sequence of the cultivated potato has the potential to greatly facilitate breeding and has been an ambition of scientists and plant breeders for many years now. With this information in hand, scientists can now more easily identify genetic variants responsible for desires or undesirables.

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Material provided by Max Planck Institute for Plant Breeding Research. Note: Content may be edited for style and length.

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