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Precision breeding creates super potato

January 12, 2010  By Fruit & Vegetable

The fall of 2009 was a truly special season for the Emsland Group.

The fall of 2009 was a truly special season for the Emsland Group.

These potatoes exclusively contain amylopectin starch.


For the first time in the history of the largest German potato starch
manufacturer, it processed Tilling potatoes, which exclusively contain
amylopectin starch. Not only can nutritional starches for emulsifying
soups and desserts be extracted from it – it can also be used for paste
and smooth coating for paper and thread production.

“This potato is the first product in Germany developed by Tilling that
achieves market readiness,” explains Prof. Prüfer of the Fraunhofer
Institute for Molecular Biology and Applied Ecology IME.

Tilling – an acronym for Targeting Induced Local Lesions in Genomes –
is a process in breeding that researchers want to use to push evolution
yet another step forward.

In nature, evolution proceeds slowly. Through mutation and selection,
plants and animal species adapt and change. Over the course of
generations, those species develop that, due to their genetic make-up,
are best adapted to the prevailing environmental conditions. Others
became extinct. For millennia, humans have been using this evolutionary
process for their own purposes, by focusing on highly productive- – and
profit yielding – species. Modern breeding processes operate the same
way, though the natural mutation rate is accelerated.

“With the aid of chemicals, a vast number of mutants can be rapidly
obtained,” says Jost Muth of IME, who participated in the development
of the new potato starch. “We are working here with natural principles.
In nature, sunlight triggers changes in the genome. With chemistry, we
accomplish the same thing – only faster.”

Until now, mutation breeding was an exhaustive process.

“Growers had to bring out the mutated seeds to the field, and then wait
until they reached the end of their vegetation period in order to
determine if one of the genetic modifications achieved the desired
result. In addition, the majority of generated mutations could not be
determined, since the characteristic is only expressed in a homozygous
state,” explains Prüfer.

His team has succeeded in accelerating the implementation. In the
laboratory at IME, the mutated seeds were germinated. As soon as the
first leaves appear, it’s harvest time: The researchers take a leaf
sample, break apart the cellular structure, isolate the genome and
analyze it. This way they can find out within a few weeks if a mutation
has attained the desired traits.

Researchers at IME, in collaboration with the Bioplant and
Emslandstärke companies, found the super potato germ. They had to
examine 2,748 seedlings until just the right one was identified that
exclusively produces the starch component amylopectin. From this germ,
experts were able to generate the first generation of super potatoes.
There are genes active in their genome responsible for the formation of
amylopectin, whereas genes that trigger the formation of amylose are
shut off.

“Until now, potatoes always contained both starch types. Industry had
to separate the amylopectin from the amylose – an energy and
cost-intensive process,” explains Prüfer. “With the Tilling potatoes,
which only contain amylopectin, this process stage is superfluous. In
Germany alone, the paper and adhesives industry require 500,000 tonnes
of highly purified amylopectin each year. Then there is the textile
industry too, which uses the starch to glaze threats prior to weaving.
The food industry is also relevant.”

This fall, 100 tonnes of the new super potato that exclusively produces amylopectin were harvested.

“They can be processed as usual in the production lines,” reports Muth.
“Special measures aren’t necessary, because the Tilling potatoes are
totally normal breeds that contain no genetically modified material.”

The example shows that conventional or modern breeding methods will
lead to success if the gene responsible for the expression of a
specific trait is a natural part of the plant, and is known to
scientists. The gene for the production of amylose in potatoes is one
such gene. “Gene technology-based processes are indispensable and it is
prudent to use them, when we want to integrate genetic material into a
plant genome – for example if we develop transgenic tobacco plants
producing pharmacological substances,” concludes Prüfer. “When it comes
to dealing with genes, there is an easy rule: as much modification as
needed, but as little as possible.”

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