Wheat has problems with damp – and drought

Our daily bread has little Norwegian wheat in it this year. Last year's wet and unstable weather is to blame. What we need now are hardy and adaptable varieties of grain. Knowing about genetic variations is part of the solution.

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Anne Kjersti Uhlen

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Wheat is one of the most widely-grown types of grain in the world, and hugely important for the world’s food supplies. While we are having problems with wet weather here in the north, it is drought that is threatening wheat production in many parts of the world. Major grain producers such as the USA, India, China, Russia and Turkey are reporting particularly poor harvests, and the price of wheat has risen enormously. In July alone, it rose by 19 per cent according to the Food and Agriculture Organisation of the United Nations (FAO).

Potentially, the climate of the future could favour wheat production in Norway, but very different and more robust varieties would be needed to tolerate a more unstable climate. We need to find out more, so that we can develop types of grain that are suited to the climate change that is facing us.

"We know what is needed to get good quality wheat. Now we want to find out how to produce varieties of good quality – whatever the weather," says Ellen Færgestad Mosleth, Senior Research Scientist at the food research institute Nofima. Together with fellow researchers Anette Moldestad and Anne Kjersti Uhlen, she has been engaged in long-term research into the quality of wheat, in close collaboration with the baking and milling industry.

Norwegian wheat doesn’t get bread to rise
Wheat contains gluten proteins that are important for baking. The gluten proteins link together to create a network that can keep the carbon dioxide gas (created by fermentation) contained within the dough, so that the bread rises. If the gluten proteins are of poor quality, the bread will not rise properly.

Damp and unstable temperatures are the enemies of the wheat field. All the rain last autumn caused wheat grains to start germinating before they were harvested, making them unsuitable for baking. In recent years, 70 to 80 per cent of the flour has come from Norwegian-grown wheat, but the forecast for 2012 is for only 17 per cent of Norwegian wheat in the flour mix.

When the wheat starts to germinate before harvesting, starch and proteins are broken down by the enzymes created by the germination process, and the quality is ruined. When the grain is bought, the effect of the enzymes that break down the starch is analysed.  A so-called falling number test is performed on all batches of wheat and rye. This will no longer be enough however, because in addition to the sprouting damage problems, the researchers have now identified a completely new phenomenon that has major consequences for wheat quality. This is about the quality of gluten proteins.

Moldestad is Project Manager of the FutureWheat project. Together with research colleagues, postdoctoral fellow Ulrike Böcker and research fellow Shiori Koga, she has investigated how wheat and wheat proteins develop during the growing season.
"We already know that even grain that has developed normally for most of the season can have its quality reduced considerably by wet autumn weather. This new phenomenon we have discovered particularly affects the gluten proteins and it appears to be due to specific enzymes that only break down proteins, not starch. We have found field samples with acceptable falling number results, but where the proteins have lost their baking properties," says Moldestad.

The extent of this protein breakdown was very great in 2011, but because of the amount of sprouting damage, the grain was not considered to be of food quality anyway. What gives us pause for thought is that if the grain had not suffered sprouting damage, the harvest would have been considered to be of food quality according to the present pricing system, but it would still have been useless for baking.

Could explain the previously unexplained differences in quality
"If we are to grow wheat in Norway in the future, we must solve this problem," says Anette Moldestad.
She is supported by Mosleth, who adds that in hindsight they see that this could explain variations that have been seen in previous years.

"These variations already existed when Uhlen and I took our doctorates on wheat quality in 1989, but we did not understand what they were. At that time it was the samples from the 1987 season, which was also cool and wet, that were abnormal. It is only later, with more challenging weather conditions, that this has become so prominent," says Mosleth.

In 2007, we saw the same problems as this year, but there was less sprouting damage then, so the mills received a lot of wheat with poor quality gluten protein. Laboratory Manager Inge Sandveen of Norgesmøllene and Nordic Product Developer Augon Hellkås of Cerealia Lantmännen can both confirm that 2007 was a difficult year. "In 2007, there were great variations within the sorting classes. To put together a flour that has stable qualities, we depend on having raw materials of predictable quality," they say.

Genetic variations could solve the problem
The outlook is not entirely black however. At least one autumn wheat on the list of Norwegian varieties managed reasonably well.

Professor Anne Kjersti Uhlen explains that the FutureWheat project is helping them to begin to understand how temperatures during the grain filling phase affect quality. It appears that we have two different phenomena. The gluten proteins are produced during the first half of the grain filling period, and our findings show that a higher temperature during this phase gives better gluten quality. The other phenomenon we see is very dramatic. The quality can be destroyed completely under certain conditions. The next step is to identify these conditions. We get a huge amount of data from many years in the field, but this must be repeated under controlled conditions so that we can be certain.

"What is very interesting is that one variety of autumn wheat largely maintained its quality, while all the other varieties in the areas that were investigated had a severe loss of quality. This shows that there are genetic variations that can be exploited," says Uhlen.

Professor Odd-Arne Olsen has been researching into a basic understanding of how grain develops and now works at the Centre for Integrative Genetics (CIGENE) at the Norwegian University of Life Sciences. Here he leads the Norwegian section of the global consortium that is working on mapping the wheat genome.

"Having one variety that maintains its quality shows that we have genes available that show resistance to this recently-discovered quality problem.  We can find molecular markers that can be used in the wheat refinement programme. We can then develop varieties that are robust in terms of how weather conditions affect the properties of gluten proteins," concludes Olsen.

Raw materials and process optimisation  

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