Impact of Seasonal and Temperature-Dependent Variation in Root Defense Metabolites on Herbivore Preference in Taraxacum officinale

Abstract

Plants experience seasonal fluctuations in abiotic and biotic factors such as herbivore attack rates. If and how root defense expression co-varies with seasonal fluctuations in abiotic factors and root herbivore attack rates is not well understood. Here, we evaluated seasonal changes in defensive root latex chemistry of Taraxacum officinale plants in the field and correlated the changes with seasonal fluctuations in abiotic factors and damage potential by Melolontha melolontha, a major natural enemy of T. officinale. We then explored the causality and consequences of these relationships under controlled conditions. The concentration of the defensive sesquiterpene lactone taraxinic acid β-D glucopyranosyl ester (TA-G) varied substantially over the year and was most strongly correlated to mean monthly temperature. Both temperature and TAG levels were correlated with annual fluctuations in potential M. melolontha damage. Under controlled conditions, plants grown under high temperature produced more TAG and were less attractive for M. melolontha. However, temperature-dependent M. melolontha feeding preferences were not significantly altered in TAG deficient transgenic lines. Our results suggest that fluctuations in temperature leads to variation in the production of a root defensive metabolites that co-varies with expected attack of a major root herbivore. Temperature-dependent herbivore preference, however, is likely to be modulated by other phenotypic alterations.

Plant volatiles as cues and signals in plant communication

“…Global warming in the Arctic tundra affected dwarf birch ( Betula nana ) to significantly increase the amount of total terpenoids in response to herbivory, revealing a strong synergy between higher temperatures and herbivory (Li, Holst, Michelsen, & Rinnan, 2019). Plant adaption to fluctuations in temperature also occurred belowground, where the production of a root defence sesquiterpene lactone taraxinic acid β‐D glucopyranosyl ester of dandelion ( Taraxacum officinale ) covaried with the mean monthly temperature and the expected attack of a major root herbivore ( Melolontha melolontha ) (Huang, Bont, Hervé, Robert, & Erb, 2020). These unique plant responses to changes in temperature through the release of specific VOCs are particularly likely to be adaptive because plants adjust their traits in a timely manner to directly cope with stress and inform the neighbours about upcoming stresses.…”

“…. Plant adaption to fluctuations in temperature also occurred belowground, where the production of a root defence sesquiterpene lactone taraxinic acid β-D glucopyranosyl ester of dandelion (Taraxacum officinale) covaried with the mean monthly temperature and the expected attack of a major root herbivore (Melolontha melolontha)(Huang, Bont, Hervé, Robert, & Erb, 2020). These unique plant responses to changes in temperature through the release of specific VOCs are particularly likely to be adaptive because plants adjust their traits in a timely manner to directly cope with stress and inform the neighbours about upcoming stresses.Moreover, conditions of drought or high salinity cause to change their volatile emission(Caparrotta et al, 2018;Jardine et al, 2015;Vivaldo, Masi, Taiti, Caldarelli, & Mancuso, 2017) (Figure 2G,H).…”

Adaptations and responses of the common dandelion to low atmospheric pressure in high altitude environments

“…Temperature, for instance, is assumed to be a good indicator for herbivore attack in the field, because herbivore appearance and activity is often modulated by temperature (Bale et al 2002). In our previous work, we found evidence that T. officinale can use seasonal temperature variation to synchronize deployment of chemical defenses with expected herbivore attack intensity in the field, indicating an important role of abiotic conditions in fine-tuning the level of constitutively produced defensive metabolites (Huang et al 2019). With increasing altitude, it is often assumed that herbivore pressure decreases (Moreira et al 2018).…”

Looking for Hidden Enemies of Metabarcoding: Species Composition, Habitat and Management Can Strongly Influence DNA Extraction while Examining Grassland Communities

“…In many cases, the resorption and translocation of plant secondary metabolites can be important strategies for perennial plants to maximize resource use across multiple growing seasons [ 91 , 92 ]. Seasonal changes in secondary metabolite content also play a crucial role in plant defense against herbivores through toxic and feeding deterrent effects, as well as the attraction of natural enemies of herbivores [ 93 , 94 , 95 ]. An example is Taraxacum officinale that significantly increases secondary metabolite content and reveals strong seasonal variation in root latex chemistry [ 93 ].…”

“…Seasonal changes in secondary metabolite content also play a crucial role in plant defense against herbivores through toxic and feeding deterrent effects, as well as the attraction of natural enemies of herbivores [ 93 , 94 , 95 ]. An example is Taraxacum officinale that significantly increases secondary metabolite content and reveals strong seasonal variation in root latex chemistry [ 93 ].…”