Potsdam Researcher Awarded Prestigious Research Grant to Optimize Plant-Microbe Interactions for Improved Crop Yields

Alexander Förderer from the Max-Planck Institute of Molecular Plant Physiology receives €2.85 million from the German Federal Ministry of Education and Research to study the harmful and beneficial relationships between plants and the microbes that surround them.

July 18, 2024

Dr. Alexander Förderer, Research Group Leader at the Max Planck Institute of Molecular Plant Physiology in Potsdam, has been awarded one of the highly prestigious BMBF Junior Group Leader grants in the “Bioökonomie” program. In his project "DETECTOME", he will investigate the molecular principles of how plants recognize the microbes around them and how they process this information for an appropriate response. His findings could contribute to a new form of agriculture that harnesses knowledge about protein structures for crop improvement.

Microbes influence plant yields

The poet John Donne wrote ‘no man is an island’. The same can be said about plants! They are surrounded by a staggering diversity of microbes. Microbes are on their leaves, around the roots, in the water and air. Some of these microbes just live on plants but hardly affect them. But not all microbes are such ‘silent’ residents. Some of them live off their plant and make it sick. They are called pathogens. Other microbes trade with the plant and deliver essential nutrients like nitrogen or phosphate in exchange for sugars or lipids provided to them by the plant. We call them symbionts.

Normally, we don’t really pay attention to these plant-microbe interactions, but when it comes to crops, we start to really care. This is because specific plant-microbe interactions dictate yield. The path of human history is paved with stories of people's constant struggle to protect their food crops from pathogens. Wheat cereal for example is plagued by the relentless stem rust fungus since its domestication in the stone-age. Potato blight, caused the Irish potato famine in the 1840s and the starvation and emigration of about a third of the Irish population. Despite international efforts, crop pandemics have become commonplace. Humans fight these diseases with adapted cultivation methods, resistance breeding and chemical agents.

The potential for improving yield by encouraging symbiotic interactions of crops with microbes is poorly explored. Farmers instead use artificial fertilizers to enhance yield. However, these fertilizers cause ecological problems and their production relies on fossil fuels, large amounts of energy and naturally occurring ores.

A fungal infection on a wheat leaf. Pathogenic fungi grow within the plant tissue and reduce the yield if the plant is unable to mount a successful immune response. Millions of tons of yield from cereals are lost to fungal pathogens. — **A fungal infection on a wheat leaf.** Pathogenic fungi grow within the plant tissue and reduce the yield if the plant is unable to mount a successful immune response. Millions of tons of yield from cereals are lost to fungal pathogens.

© sevens+maltry

**A fungal infection on a wheat leaf.** Pathogenic fungi grow within the plant tissue and reduce the yield if the plant is unable to mount a successful immune response. Millions of tons of yield from cereals are lost to fungal pathogens.

© sevens+maltry

The research of Dr. Alexander Förderer aims to improve the resistance of crops to pathogens and to equip them for the benefits of symbiosis

“The key to improving crop yields by improving the plants’ response to microbes lies in their receptors”, says Alexander Förderer. Receptors are specific proteins and many of them are used by the plant to recognize and differentiate between microbes. Plants have hundreds of them. Like the receptor proteins in our noses detect odor molecules to create a sensation of smell, plants use receptors to detect molecules that originate from the surrounding microbes. Depending on whether the plant detects molecules from symbiotic or from pathogenic microbes its reaction differs.

In case a pathogenic microbe is detected, the plant mounts a powerful immune response with the intention to block any further invasion by the pathogen. A resistant crop cultivar that has a specific receptor to detect a certain pathogen can resist the attack. A susceptible crop cultivar succumbs to the pathogen invasion, typically because it lacks a specific receptor to detect the pathogenic microbe.

A plants’ reaction to symbiotic partners is vastly different. If the right combination of molecules from a symbiotic partner is detected, the plant allows the microbe to grow within its tissue. Even more so, many plants have evolved features to even encourage this colonization and to actively deliver resources to such a microbial partner. How successfully this mutually beneficial relationship can develop, varies much between different crops. The natural variation in the ability of plants to detect beneficial and pathogenic microbes, to distinguish between friend and foe, is the focus of the research project.

Cryo-EM structure of a plant receptor (green) in complex with proteins from a pathogenic rust fungus (red). The globular protrusions are individual atoms on the surface of the protein molecules. The insight on the atomic level allows researchers to understand how some receptors can, and others cannot recognize a certain microbe.

© Alexander Förderer

Cryo-EM structure of a plant receptor (green) in complex with proteins from a pathogenic rust fungus (red). The globular protrusions are individual atoms on the surface of the protein molecules. The insight on the atomic level allows researchers to understand how some receptors can, and others cannot recognize a certain microbe.

© Alexander Förderer

Insights with atomic resolution

Plants have a remarkable ability to detect nearby microbes, but the differences between plants that can do this effectively and those that cannot are often very small. Sometimes, just minor changes in the amino acid composition of a receptor protein determine if a plant variety can resist a microbe, or if it is able to form a beneficial relationship with another microbe.

To understand how these minor differences in receptors affect their ability to detect microbes, the group uses cryo-electron microscopy (cryo-EM). Cryo-EM is a cutting-edge technique from the field of structural biology, which allows to see the structure of proteins with atomic detail. It uses a powerful electron microscope to take thousands of detailed images of protein particles from different angles to create a 3D model of the protein molecule. By deciphering how slight changes in the composition of the receptor molecule affect its shape and function, it is possible to determine which atomic differences are crucial. Such knowledge allows to focus efforts of gene editing and breeding techniques on those few amino acids that are crucial for the function of the receptor, narrowing down the number of targets from hundreds to a handful. This is a crucial step on the road towards equipping crop plants with receptors that are better able to recognize and react to all types of microbes, be they pathogenic or symbiotic.

Dr. Alexander Förderer

Alexander Förderer is a research group leader at the Max Planck Institute of Molecular Plant Physiology at Potsdam Science Park. He heads the team ‘receptor structures at the plant-microbe interface’ and specializes in the interactions between plants and microbes.

With its Bioeconomy agenda, the German Federal Ministry of Education and Research (BMBF) supports research projects by top researchers at an early-career stage who want to boldly advance into innovative research and that has the potential to shape a future economy relying on biogenic resources and biological knowledge for more sustainability. The award procedure is highly competitive and the success rate is less than 10%. Next to „DETECTOME“, only 2 more research projects were funded in 2024 in Germany.