How plants handle multiple stresses: hormonal interactions underlying responses to abiotic stress and insect herbivory.
Adaptive plant responses to specific abiotic stresses or biotic agents are fine-tuned by a network of hormonal signaling cascades, including abscisic acid (ABA), ethylene, jasmonic acid (JA) and salicylic acid. Moreover, hormonal cross-talk modulates plant responses to abiotic stresses and defenses against insect herbivores when they occur simultaneously. How such interactions affect plant responses under multiple stresses, however, is less understood, even though this may frequently occur in natural environments. Here, we review our current knowledge on how hormonal signaling regulates abiotic stress responses and defenses against insects, and discuss the few recent studies that attempted to dissect hormonal interactions occurring under simultaneous abiotic stress and herbivory. Based on this we hypothesize that drought stress enhances insect resistance due to synergistic interactions between JA and ABA signaling. Responses to flooding or waterlogging involve ethylene signaling, which likely reduces plant resistance to chewing herbivores due to its negative cross-talk with JA. However, the outcome of interactions between biotic and abiotic stress signaling is often plant and/or insect species-dependent and cannot simply be predicted based on general knowledge on the involvement of signaling pathways in single stress responses. More experimental data on non-model plant and insect species are needed to reveal general patterns and better understand the molecular mechanisms allowing plants to optimize their responses in complex environments.
Molecular Plant Physiology, Institute for Water and Wetland Research (IWWR), Radboud University, PO Box 9010, 6500 GL, Nijmegen, The Netherlands.
Duy
D
Nguyen
Molecular Plant Physiology, Institute for Water and Wetland Research (IWWR), Radboud University, PO Box 9010, 6500 GL, Nijmegen, The Netherlands.
Ivo
I
Rieu
Molecular Plant Physiology, Institute for Water and Wetland Research (IWWR), Radboud University, PO Box 9010, 6500 GL, Nijmegen, The Netherlands.
Celestina
C
Mariani
Molecular Plant Physiology, Institute for Water and Wetland Research (IWWR), Radboud University, PO Box 9010, 6500 GL, Nijmegen, The Netherlands. nicole.vandam@idiv.de.|German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Deutscher Platz 5e, 04103, Leipzig, Germany. nicole.vandam@idiv.de.|Institute of Ecology, Friedrich Schiller University Jena, Dornburger-Str. 159, 07743, Jena, Germany. nicole.vandam@idiv.de.
Nicole M
NM
van Dam
D000818:Animals; D060434:Herbivory / Q000187:drug effects*; D007313:Insecta / Q000502:physiology*; D063245:Plant Development / Q000187:drug effects; D010937:Plant Growth Regulators / Q000494:pharmacology*; D010944:Plants / Q000187:drug effects / Q000469:parasitology*; D013312:Stress, Physiological / Q000187:drug effects*
D010937:Plant Growth Regulators
Drought; Flooding; Herbivory; Hormonal cross-talk; Induced resistance; Stress responses