Prof. Dr. Jürgen Zeier

Our research investigates the metabolic and biochemical events that regulate plant-environment interactions. As a major research interest, we study a phenomenon designated as systemic acquired resistance (SAR), a plant immune response that confers broad-spectrum disease resistance to microbial pathogens and primes plants for effective defense activation. In context with this SAR, the biosynthesis and metabolic conversion of immune-active small molecules guarantee plants to maintain a fine-tuned balance between growth and defense. This metabolic homeostasis allows plants to optimally adapt to their biotic environment and further determines their interaction with pathogenic, commensalistic and beneficial microorganisms. In the past years, we have elucidated an L-Lys-derived three-step and stress-inducible plant biochemical pathway that results in the formation of N-hydroxypipecolic acid (NHP) as a novel mobile immune regulator (1-3; 5-8). Alongside with its direct biochemical precursor pipecolic acid (Pip) and the phenolic stress hormone salicylic acid (SA), NHP accumulates in the whole plant foliage upon biotic stress and induces SAR and the primed state associated with SAR. Remarkably, SAR signal transduction is terminated by coincident metabolic conversion of NHP and SA by a single glycosyltransferase, which catalyzes the formation of biologically inactive NHP- and SA-glucosides. Within CEPLAS, we investigate the interplay between microorganisms and plants on the basis of complementary, pipecolate pathway-related metabolic activities of these interaction partners. We aim at identifying and biochemically characterizing novel pipecolate-metabolizing activities of rhizosphere-associated and root endophytic bacteria and examine whether pipecolate synthesis mediated by a particular microbial soil composition can enhance pathogen resistance in the shoot. We further study the influence of specify edaphic environments on plant metabolism in roots, and investigate the function of (secondary) metabolites in adaption to these environments and shaping the composition of the root microbiome.