Increasing yields, securing the food supply

Indeed, the FAO data indicates that global food production will have to almost double by 2050. But while the number of people increases by around 80 million every year, the amount of arable land per person available for growing food continues to shrink in proportion. “The global potential for creating new agricultural land is seriously limited, and the available acreage is even declining in many countries – due to water scarcity, soil erosion and desertification,” warns Prof. Chiara Tonelli, Professor of Genetics at the University of Milan in Italy. If food production is to keep up with demand, then the productivity of crops must increase significantly – as many experts will confirm.
Scientists are therefore working intensively to develop plants that produce higher yields. Drought tolerance and fertilizer uptake are also important targets in the development of new varieties, because global climate change might exacerbate the current supply challenges. In fact, classical methods of cross-breeding are unlikely to meet the high demands imposed on the crops of the future. But rapid progress in plant biotechnology in recent years has made new tools available to breeders and researchers: “Biotechnological methods don’t just accelerate plant breeding considerably, they also complement the many years of traditional breeding experience,” says Dr. Johan Botterman, Head of Product Research in BioScience at Bayer CropScience. Using the new breeding techniques, plants can be equipped with the desired properties more quickly.

“This is thanks mainly to progress in gene sequencing“, explains Dr. Michael Metzlaff, Manager of Research Collaborations for BioScience at Bayer Crop­Science. Genes – and their functions – can now be identified much more easily than was the case ten years ago. Since the decoding of the genome of the model plant Arabidopsis thaliana, researchers have ever more accurate and novel insights into the interplay of plant genes, their functions and mutual relationships. In the meanwhile, researchers have also decoded the genomes of some major crops, including corn, rice and oilseed rape.

Prof. Tonelli mentions only one example among many: “Plant biotechnology allows us to identify the most important genes involved in water use and drought tolerance.” Often, whole networks of genes are responsible for the desired characteristics. These complex networks, with their many cross-links, are what biotechnologists and plant breeders are trying to decipher and understand.

Raising yields, improving quality

One modern method that takes the researchers to the heart of the plant cell – to the genome, within the nucleus – is ‘Molecular Breeding’. Analytical techniques like this usually give a much more detailed insight into a plant than is revealed to the naked eye. These tools allow the breeding experts of Nunhems to know, for example, how hot a chili pepper is likely to taste – long before it develops on the plant. Indeed, it is possible to change one or more genes through skillful crossing and selection in the laboratory to ensure that the plant expresses the desired property. “This targeted approach to selection saves an enormous amount of development time, space in the greenhouse and field trials – enabling us to better meet market demands,” comments Dr. Jan van den Berg, Head of Molecular Breeding for Nunhems, the vegetable specialists at Bayer CropScience.

Together with a group of colleagues including molecular geneticists, biochemists and bioinformaticians, van den Berg is working to characterize new properties of vegetables that are associated with the quality of the fruit, resistance to disease, and yield. This represents a shift in the work of plant breeders from the field to the laboratory – and not least to the computer. For this is where the real challenge begins: bioinformaticians and statisticians have to analyze, and then interpret, the many data. Using computer databases, they develop gene maps that help them to screen the genetic profile for the genes behind specific plant properties. Then, using computer analysis, researchers and breeders even try to define complete crossing programs for developing new varieties. “Our computer models now provide very reliable forecasts – before we even start our field trials,” Botterman confirms.

Whereas researchers have traditionally identified the genes they’re interested in on the basis of a plant’s appearance, the team led by Dr. Bart Lambert, Product Research Manager for Oilseeds in BioScience performs exactly the opposite of this process: using so-called “reverse genetics”, the scientists change a gene or gene network specifically in order to equip the plant with a new characteristic. To this end, they treat the seeds with a substance that causes gene mutations, which then become randomly distributed across the genome. “Changes like this also occur in nature. But we speed up the process of evolution in a targeted way,” is how Lambert describes the approach. Taking thousands of mutant seed samples, the scientists use conventional methods to select out individuals that carry a promising mutation in their genetic material, and then cross them into new varieties.
Bayer CropScience wants to use “reverse genetics” to solve a problem that currently faces many rapeseed farmers: seeds often fall to the ground from mature rape pods before harvesting. BioScience researchers are developing plants whose pods do not split so easily. To this end, they have identified a specific gene that is involved in controlling the development of pod tissues. They now know how to change the activity of the gene such that the rape pods are more stable – and thus more resistant to splitting.

Developing new seeds: speeding up evolution

Whilst providing their plants with the capacity for higher yields and increased resistance, the reserarch team at the Innovation Center of Bayer CropScience in Ghent also relies on the still relatively young field of epigenetics. This line of research deals with the influence of environmental factors on networks of genes. For example, the researchers were able to clarify why some oilseed rape plants grow better than others under certain circumstances – despite sharing the same genetic make up. In fact, stress can trigger the appearance in plant cells of short, single-stranded ribonucleic acid (RNA) molecules that turn off individual genes and thereby inhibit plant growth. If cell biologists can learn to interpret these epigenetic mechanisms even better, they will be able to use this knowledge in future to switch on and off genes in a more targeted way.

	Using full-automated gene analysis and molecular markers, Bayer CropScience's biotechnology experts are able to investigate samples from several thousand plants each day. The results help towards targeted breeding of vegetable varieties.

So – from the targeted insertion of the desired properties, through the switching on and off of individual genes or networks of genes, to the traditional methods of selecting and crossing – plant breeders now have an extensive toolbox. And by cleverly combining proven technologies, these processes can be markedly accelerated. Take hybrid breeding, for example: this method takes advantage of the so-called heterosis effect. This phenomenon can be observed when crossing two pure-bred parental lines that are genetically as different as possible. They produce offspring that are capable of improved performance: the new hybrids are better yielding and more stress-tolerant than conventional varieties. Bayer CropScience is one of the leading breeding companies of hybrid rice and oil seed rape varieties.

“The breeding process itself is not a secret. The trick is rather to determine the right locations to select parents with the right properties that are suited to the particular markets in question and then combine the right parents,” says Paul Degreef, Head of Plant Breeding at Nunhems. To meet the needs of their customers, the researchers are turning to their global infrastructure: with three research centers and 26 breeding sites in 14 countries, there is a strong network of cooperation with international colleagues – along with an extensive exchange of germplasm, usually material that already has one or two interesting features. And this is where the new molecular markers become important again: “They are used to identify the most promising lines from the large available pool of seed, thus all the better to steer and speed up the selection process,” says Dirk Decherf, a oilseed rape breeder for Bayer CropScience.

The molecular markers allow the development of an enormous variety of new plants that differ only in terms of small nuances, each of which meets a particular customer’s requirements. In this way, Nunhems has developed more than half of its 2,500 varieties of vegetable seeds in just the last six years. More will follow. Because the expectations made of each individual seed remain great.