How plants handle multiple stresses: hormonal interactions underlying responses to abiotic stress and insect herbivory

Abstract

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.

Influence of drought on plant performance through changes in belowground tritrophic interactions

“…Soil moisture may influence the impact of herbivores on plant performance (Gray & Steffey, 1998; Jamieson, Trowbridge, Raffa, & Lindroth, 2012) and chemistry (Erb & Lu, 2013; Nguyen, Rieu, Mariani, & van Dam, 2016). We found that WCR attack reduced plant height and accentuated the effect of low soil moisture on the onset of silk emergence.…”

Engineering abiotic stress response in plants for biomass production

“…Knockout T-DNA insertion mutant of Osgsk1 (a rice GSK3/SHAGGY-like protein kinase gene, ortholog of AtBIN2/AtSK21, a negative regulator of BR-signaling), depicted enhanced tolerance towards abiotic stress, while OsGSK1 overexpression resulted in stunted growth in Arabidopsis (80). In addition, hormones target various members of protein families playing a significant role in growth either individually or in co-regulated manner, thereby indicating the synergistic action of metabolic pathways (81). Biotechnological manipulation of these key proteins could allow not only the adaptation under adverse environmental conditions, but also determine the flux in phytohormone biosynthesis for securing, in the long run, improved food production.…”

Cumulative herbivory outpaces compensation for early floral damage on a monocarpic perennial thistle

“…Plant resource condition, herbivore dynamics, phenological overlap with shared hosts and pollinators or competing predators, and timing of damage can influence the degree of plant tolerance (Kolb et al 2007;Wise and Abrahamson 2007;von Euler et al 2014;Lehndal and Ågren 2015;Krimmel and Pearse 2016;Stieha et al 2016;Kafle et al 2017). Co-occurring stressors may further interact with cumulative herbivory pressure to inhibit successful tolerance (Lay et al 2011;Nguyen et al 2016). Population-level effects of herbivory have been well-documented in C. canescens.…”