Chemical Ecology of Plant-herbivore Interactions

Plants produce a puzzling diversity of defensive chemicals in their struggle to deter herbivorous enemies. Complex chemical mixtures may present defensive advantages over single compounds, for example via multi-target toxicity or compound-compound facilitation. Chemical diversification is therefore considered a strategy to escape coevolved herbivores. At the same time, such diversification must be costly to the plant, in terms of both raw building blocks and maintenance costs for increasingly complex synthesizing machinery.

We aim to elucidate the selective forces that drive chemical diversification. We use a newly established model plant system and employ a combination of experimental ecology and different techniques including metabolomics, transcriptomics, and phylogenetic comparisons. In a two-pronged approach, we focus on the defensive benefits of diverse chemical mixtures via altered feeding behavior and success of generalist and specialist herbivores, as well as on the cost of diversification in terms of negative impact on plant growth and reproduction. Ultimately, we will thus be able to link variation in genes and metabolites to success in a variable and changing environment.

• Evolution of cardiac glycosides in Erysimum spp.
• Molecular mechanisms of phytochemical diversification
• Inducible defenses and growth costs
• Herbivore tolerance to basal and novel defenses
• Sequestration of plant toxins and higher-trophic interactions

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• Quantification of plant cardenolides by HPLC, measurement of Na+/K+-ATPase inhibition activity, and characterization of target enzymes.
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  Methods in Enzymology 680, 275-302, 2023
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• Evidence for tissue‐specific defence‐offence interactions between milkweed and its community of specialized herbivores
  X López‐Goldar, A Hastings, T Züst, A Agrawal
  Molecular Ecology 31 (11), 3254-3265, 2022
• Sequestration of defenses against predators drives specialized host plant associations in preadapted milkweed bugs (Heteroptera: Lygaeinae)
  G Petschenka, R Halitschke, T Züst, A Roth, S Stiehler, L Tenbusch, ...
  The American Naturalist 199 (6), E211-E228, 2022
• Metabolization and sequestration of plant specialized metabolites in insect herbivores: Current and emerging approaches
  AM Jeckel, F Beran, T Züst, G Younkin, G Petschenka, P Pokharel, ...
  Frontiers in physiology, 1905. 2022
• Soil chemistry determines whether defensive plant secondary metabolites promote or suppress herbivore growth
  Hu, Lingfei; Wu, Zhenwei; Robert, Christelle A. M.; Ouyang, Xiao; Zust, Tobias; Mestrot, Adrien; Xu, Jianming; Erb, Matthias
  Proceedings Of The National Academy Of Sciences Of The United States Of America 10.1073/pnas.2109602118 OCT 26 2021
• Predator-induced maternal effects determine adaptive antipredator behaviors via egg composition
  Sharda, Sakshi; Zuest, Tobias; Erb, Matthias; Taborsky, Barbara
  Proceedings Of The National Academy Of Sciences Of The United States Of America 10.1073/pnas.2017063118 SEP 14 2021
• Using plant chemistry to improve interactions between plants, herbivores and their natural enemies: challenges and opportunities
  Erb, Matthias; Zuest, Tobias; Robert, Christelle Aurelie Maud
  Current Opinion In Biotechnology 10.1016/j.copbio.2021.05.011 AUG 2021
• Herbivore-induced plant volatiles mediate defense regulation in maize leaves but not in maize roots
  van Doan, Cong; Zust, Tobias; Maurer, Corina; Zhang, Xi; Machado, Ricardo A. R.; et al.
  Plant Cell And Environment 10.1111/pce.14052  Early Access: APR 2021
• The plant metabolome guides fitness-relevant foraging decisions of a specialist herbivore
  Machado, Ricardo A. R.; Theepan, Vanitha; Robert, Christelle A. M.; Zust, Tobias; Hu, Lingfei; Su, Qi; Schimmel, Bernardus C. J.; Erb, Matthias
  PLOS BIOLOGY 19(2) Article Number: e3001114, DOI: 10.1371/journal.pbio.3001114   FEB 2021
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