plant-insect interactions; detoxification by insect herbivores; plant defence chemistry; crop protection; interspecific metabolic networks
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Li B., Förster C., Robert C. A. M., Züst T., Hu L., Machado R. A. R., Berset J.-D., Handrick V., Knauer T., Hensel G., Chen W., Kumlehn J., Yang P., Keller B., Gershenzon J., Jander G., Köllner T. G., Erb M. (2018), Convergent evolution of a metabolic switch between aphid and caterpillar resistance in cereals, in Science Advances
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Hu L., Mateo P., Ye M., Zhang X., Berset J. D., Handrick V., Radisch D., Grabe V., Köllner T. G., Gershenzon J., Robert C. A. M., Erb M. (2018), Plant iron acquisition strategy exploited by an insect herbivore, in Science
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Hu Lingfei, Robert Christelle A. M., Cadot Selma, Zhang Xi, Ye Meng, Li Beibei, Manzo Daniele, Chervet Noemie, Steinger Thomas, van der Heijden Marcel G. A., Schlaeppi Klaus, Erb Matthias (2018), Root exudate metabolites drive plant-soil feedbacks on growth and defense by shaping the rhizosphere microbiota, in NATURE COMMUNICATIONS
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Robert Christelle AM, Zhang Xi, Machado Ricardo AR, Schirmer Stefanie, Lori Martina, Mateo Pierre, Erb Matthias, Gershenzon Jonathan (2017), Sequestration and activation of plant toxins protect the western corn rootworm from enemies at multiple trophic levels, in eLife
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Activation of secondary metabolites by de-glycosylation is a widespread anti-herbivore defense strategy which allows plants to store harmless glycosides and hydrolyze them to toxic or deterrent products upon attack. However, various specialized herbivores can re-glycosylate the activated toxins and store them for self-defense. Although glyco-modulation has been described in a number of systems, a detailed understanding of the biochemical mechanisms and ecological consequences is lacking. The interactions among maize plants, the western corn rootworm (WCR) and its natural enemies, such as entomopathogenic nematodes (EPNs) and parasitoids are ideally suited to study the ecological as well as agricultural significance of defensive glyco-modulation (Figure 1). WCR is a key pest of maize, and entomopathogenic nematodes are highly promising biocontrol agents. The main insect resistance factors in maize roots are 1,4-benzoxazin-3-one derivatives (BXDs), which are stored as glucosides and activated by plant ß-glucosidases. During a previous Sinergia project, we have found that the specialized WCR larvae are fully tolerant to BXDs and accumulate stabilized BXD glycosides upon BXD ingestion. Larval tissue disruption results in the rapid re-activation by putative insect ß-glucosidases, which is associated with increased resistance against natural enemies. BXD glyco-modulation is therefore a key process that may explain the success of WCR as a maize pest. As a next step, this project will identify and characterize BXD glyco-modulation enzymes in maize and WCR, manipulate them using reverse genetics and investigate their role in tritrophic interactions below ground. To achieve this goal, we will combine expertise in analytical chemistry, biochemistry, molecular physiology and ecology to: 1) develop a next-generation analytical toolbox to identify and trace BXDs across cell organelles, tissues and trophic levels using cell fractionation, 2H labeled precursors and sensitive absolute quantification methods; 2) identify and analyze maize BXD ß-glucosidases and ß-glucosidase aggregating factors as well as WCR glycosyl transferases and ß-glycosidases; 3) generate maize mutants and transiently silenced WCR larvae that are defective in BXD glyco-modulation 4) use the generated transformants to assess how BXD glyco-modulation affects WCR resistance to natural enemies. The above activities will result in the following output: 1) A comprehensive integrative set of unique research tools, including novel analytical methods, chemical and biochemical reagents, maize mutants and transformed strains. 2) Knowledge on the mechanistic basis of glyco-modulation as a general phenomenon in plant herbivore-interactions. 3) A detailed understanding of the importance of secondary metabolite hijacking for soil tritrophic interactions and biological control. By investigating glyco-modulation in a molecular, multitrophic context using an interdisciplinary approach, we expect push the boundaries of an important frontier in plant-insect interactions.