In collaboration with national and international experts, researchers from Aarhus University have revealed new fundamental features of biomolecular interactions that enable plants to identify and respond appropriately to microorganisms. The new results provide a better understanding of the mechanisms governing the ability of plants to interact with beneficial microorganisms while being resistant to pathogenic bacteria and fungi. This could have implications for future sustainable agriculture, where useful microorganisms are increasingly sought to replace pesticides.
Plant roots are surrounded by thousands of bacteria and fungi living in the soil and on the root surface. To survive in this diverse environment, plants employ sophisticated detection systems to distinguish pathogenic microorganisms from beneficial microorganisms.
Here the so-called chitin molecules from microorganisms, along with modified versions, play an important role as they are detected by the plant surveillance system. Legumes, for example, build a defence against pathogenic microorganisms in response to simple chitin molecules.
However, when the plant detects a specific modified chitin molecule (called a Nod factor) that is secreted from the rhizobium soil bacteria, formation of new organs in the form of "root nodules" occurs. Rhizobium bacteria are allowed to enter and colonise in these symbiotic organs, and they ultimately produce nitrogen for the plant.