Different Bread for the World
The unequal distribution of food is a major reason for hunger in the world. However, in order to ensure adequate food for the growing global population, additional agricultural crops are required.
Wheat, rice and maize - these three crops cover 50 percent of our calorie requirement worldwide. Diversity over the fields must increase if we are to be able to ensure enough food for the future.
Image: Thomas Lohnes / Brot für die Welt
"With current cultivation methods and the existing crops, we will not manage to still be able to feed the world in 20 years. We must continue breeding new crops." This was the conclusion on plant research reached by the Kiel Professor Karin Krupinska, during a panel discussion at the Botanikertagung 2017 (International Plant Science Conference) in Kiel, where she served as president of the congress. The problem is not only the world's growing population, but also the deterioration in growing conditions caused by climate change.
"The amount of usable agricultural land is decreasing, therefore we must also utilise marginal areas." This means that increasingly, land will be used which is not really well-suited for agriculture, for example because it is too dry or too salty, is often flooded, or is exposed to extreme temperatures. Crops of the future must be able to deal with these external stress factors (stressors).
"We must improve our understanding of how plants adapt to environmental stress," said the head of the Plant Cell Biology working group at Kiel University. Rice, for example, easily copes with flooding of the fields due to its anatomical properties, whereas "normal" plants rot under water because no gas exchange is possible. How does this work in rice? Which genes become active, in order to make this possible? This knowledge is the key to making other plants resistant to flooding.
Another stressor is light. Although plants need light for photosynthesis, getting the right amount is critical. If plants get too little light, they cannot fulfil their potential. "But too much light can lead to the formation of reactive oxygen species, which destroy the photosynthetic apparatus. So this must be properly monitored." Krupinska’s working group researches how plants deal with this light stress.
One possible approach to increase the stress resistance of crops is so-called "rewilding", i.e. restoring important properties of the original wild plants, the ancestors of today's crops. In the course of breeding high-yield crops, important properties of these wild plants have been lost, for example resistance to plant diseases.
"We crossbreed and crossbreed, mix up the genome, and select only according to yield or a specific attribute, during which other properties are lost. Here, I only need to look at what wild plants have available, in order to protect themselves. Often, these functions are lost due to a single point mutation. Professor Michael Broberg Palmgren from the University of Copenhagen drew attention to this in a lecture." With the so-called CRISPR/Cas9 method, an innovative and precise biochemical process, it is possible to correct such mutations in the genome in a targeted manner.
However, we not only require plants that are resistant to harsh environmental conditions. It is just as important to cultivate high-yield plants. According to Krupinska, a significant increase in the yield per square meter can be achieved primarily by the cultivation of C4 plants (see info box), which conduct more efficient photosynthesis. C4 plants, such as maize or sugar cane, generate more biomass in a shorter period of time than C3 plants, which include most of our existing crops.
A further advantage of C4 plants is that they have also adapted to warmer regions with higher light exposure. Due to these advantages, research groups worldwide are looking for ways to modify traditional C3 plants in such a way that they can conduct photosynthesis like a C4 plant. "It would be great to make wheat or rice into a C4 plant," said Krupinska. This is the goal set for rice by a large research institute in the Philippines, the International Rice Research Institute (IRRI).
For the agricultural production of the future, it is also important to better select appropriate plants for the respective locations. Krupinska: "We would need to analyse which plants cope with which climate the best. On the one hand, we could learn how the plants we would like to cultivate would have to be modified. On the other hand, it also helps with selecting correctly. There is much that can be done here."
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