Breeding plants that respond better to biologicals

The paper From chemicals to biologicals, breeding plants for transformative sustainable agriculture was published in Trends Open, a Cell Press journal. The study was carried out by PhD candidate Mohammadhadi Sobhani and Richard Visser, Emeritus Professor of Plant Breeding at WUR.

Biologicals are naturally derived products that can help plants grow better, use nutrients more efficiently or cope better with stress caused by diseases, pests, drought or heat. Examples include micro-organisms that stimulate root growth, or natural substances that strengthen a plant’s resilience. They are seen as a building block for more sustainable agriculture. As demand for food rises, soil quality declines, biodiversity decreases and chemical inputs become less available and, more importantly, less desirable, the need for biologicals is growing.

Although the use of biologicals is increasing, their share compared with chemical products remains relatively low. At first glance, this is sometimes attributed to the higher cost of biological products. But according to researcher Mohammadhadi Sobhani, a more important reason is that biologicals are still less studied than chemical products and their efficacy is often less predictable in practice.

“Biologicals do not always work equally well. Their effectiveness can differ by variety, from negative to positive. Producers often make general claims about how a biological works, even though within a crop, such as potato or tomato, it may have been tested on only one variety, or rarely on a few varieties. As a result, farmers may see inconsistent results in yield improvement and stress management, and may revert to more reliable chemical products. If we can show that a crop variety responds well to a particular biological, we increase the chance of gaining farmers’ trust and making them use biological products more often.”

Four factors play an important role in the effectiveness of a biological: the type of biological, the environment, the type of plant stress the product is being used against, and the plant’s genetic make-up. So far, research into the effects of biologicals has focused mainly on the biological products themselves and on the type of plant stress, with far less attention paid to the role of the environment and genetics. Yet that last factor may be crucial in determining whether a biological has a positive, negative or neutral effect on a plant. Sobhani says: “There are studies showing that genetic make-up can play a role, but they looked at only a few genotypes. That is too little to generate enough knowledge in this area.”

If the genetic make-up of a variety partly determines whether a product works well, the plant itself also becomes part of the solution. The question is then not only: which biological product fits this crop? But also: which variety responds favourably to this product? That may be important for breeders. While breeders currently select for traits such as yield, quality and disease resistance, in future they may also look at how a variety responds to a biological. In their paper, the researchers call this “an underexplored route to making biologicals more reliable and using them more effectively in sustainable agricultural systems”.

According to Richard Visser, it is not easy to demonstrate the extent to which crop genetics plays a role in the effectiveness of a biological. “Each variety has its own traits and resistance genes against different diseases and pests. The challenge is to find out whether the effectiveness of a product is caused by the biological component of the product, or by the presence or absence of certain resistance genes. Initially, we hope to identify genes or processes that cause a plant to perform better or worse after a product has been applied. That knowledge can help breeders avoid certain genes or actively introduce them.”

The researchers are starting with experiments in which they will study the effects of two biologicals on 20 to 30 different potato genotypes. Sobhani explains why they chose this crop. “First of all, potato has a highly diverse genetic background. That makes it very suitable and interesting for genetic research. In addition, potato is one of the world’s most important food crops. At the same time, it is also the crop whose production currently depends heavily on chemicals. Around half of all chemical crop protection products in the Netherlands are used in potato. If we know to what extent genetic make-up plays a role in the effectiveness of biologicals, that could make an important contribution to potato cultivation with reduced reliance on chemical inputs, including in an organic production environment.”

Visser also hopes to involve breeders and other partners from the sector in the research over the coming years. “Although our research is still very much in its infancy, it is important to start familiarising the sector with this idea now. To many breeders, this sounds like something for the more distant future, but they do have valuable expertise at this stage of our research and can provide useful and critical feedback. Fortunately, several breeding companies have indicated that they would like to exchange thoughts and ideas with us in the period ahead. For even broader input, we also hope to get producers of biologicals on board.”