Close and distant: Contrasting the metabolism of two closely related subspecies of Scots pine under the effects of folivory and summer drought

Abstract

Metabolomes, as chemical phenotypes of organisms, are likely not only shaped by the environment but also by common ancestry. If this is the case, we expect that closely related species of pines will tend to reach similar metabolomic solutions to the same environmental stressors. We examined the metabolomes of two sympatric subspecies of Pinus sylvestris in Sierra Nevada (southern Iberian Peninsula), in summer and winter and exposed to folivory by the pine processionary moth. The overall metabolomes differed between the subspecies but both tended to respond more similarly to folivory. The metabolomes of the subspecies were more dissimilar in summer than in winter, and iberica trees had higher concentrations of metabolites directly related to drought stress. Our results are consistent with the notion that certain plant metabolic responses associated with folivory have been phylogenetically conserved. The larger divergence between subspecies metabolomes in summer is likely due to the warmer and drier conditions that the northern iberica subspecies experience in Sierra Nevada. Our results provide crucial insights into how iberica populations would respond to the predicted conditions of climate change under an increased defoliation in the Mediterranean Basin.

Insect defoliation is linked to a decrease in soil ectomycorrhizal biomass and shifts in needle endophytic communities

“…Our results regarding tree chemical defences can only be interpreted as a post-defoliation tree physiological status, therefore we cannot speculate whether differences in chemical defences influenced tree selection by the PPM. Second, chemical defensive differences between defoliated and non-defoliated trees could be the result of genotypic or phenotypic differences among individual trees that have conditioned the host selection by the PPM (Rivas-Ubach et al 2017). In any case, several studies have reporteds a weak or unclear influence of tree volatiles and defensive chemistry on tree selection for oviposition by this insect (Hódar et al 2002;Jactel et al 2011), whereas oviposition is determined by stand structure and composition characteristics for landscape factors such as appariency and the presence of non-host trees (Hódar et al 2002;Jactel et al 2011;Dulaurent et al 2012;Régolini et al 2014).…”

Experimental Design and Sample Preparation in Forest Tree Metabolomics

“…In forest tree research, LC-MS instruments have also been used for untargeted secondary metabolite profiling and phytohormone quantification studies. The focus of these studies was related with abiotic stress responses [19][20][21][22][23][24]67,88,89]; and to a smaller extent to biotic stress responses [90,91] and plant growth and developmental processes [77,92,93].…”

“…Metabolite extraction for LC-MS untargeted analysis are usually performed using a simple protocol based on methanol [19] or methanol:water 80:20, v/v [20,91] or 50:50, v/v [90] as extraction solvents. However, most untargeted secondary metabolite profiling studies in forest tree metabolomics research are performed in combination with GC-qMS or GC-TOF-MS primary metabolite profiling, ultimately allowing for more comprehensive coverage of the tree metabolome.…”

We Are What We Eat: A Stoichiometric and Ecometabolomic Study of Caterpillars Feeding on Two Pine Subspecies of Pinus sylvestris

“…Ecometabolomics, the study of the ecosystem structure and function through metabolomics analyses [28,29,30,31,32,33], has proven to be useful to understand the metabolic changes of organisms under the pressure of biotic and/or abiotic stressors [22,31,34,35,36,37,38]. The metabolome is defined as the total set of metabolites present in the organism at a particular abundance and moment [39].…”

“…The main aim of this study is to examine whether caterpillars of PPM feeding on different plant hosts (subspecies of P. sylvestris ( nevadensis and iberica )) present distinct metabolomes and nutritional properties. Although nevadensis and iberica belong to the same species, their overall metabolome structure and nutrient concentrations have proven to be significantly different [23,36]. We hypothesize that metabolomic differences between pine subspecies can lead to changes of insect herbivore metabolomes despite having physiological and metabolic mechanisms to regulate nutrient intake for maintaining body homeostasis.…”