Implications of mistletoe parasitism for the host metabolome: A new plant identity in the forest canopy Lázaro González, Alba Hodar Correa, José Antonio Zamora Rodríguez, Regino Jesús Ecometabolomic Mistletoe-host system Oxidative stress Permanent and systemic effects Plant-plant interaction Seasonality Catalan Government, Grant/Award Number: SGR 2017-1005; European Research Council Synergy, Grant/Award Number: IMBALANCE-P ERC-2013-SyG-610028; Ministerio de Ciencia e Innovacion, Grant/Award Numbers: CLAVINOVA CGL2011-29910, ELEMENTALSHIFT PID2019-110521GB-I00; Ministerstvo Skolstvi, Mladeze a Te. lovychovy, Grant/Award Number: SustES CZ.02.1.01/0.0/0.0/16_019/0000797; Secretaria de Estado de Investigaci ~on, Desarrollo e Innovaci~on, Grant/Award Number: BES-2012-057125 Mistletoe–host systems exemplify an intimate and chronic relationship where mistletoes represent protracted stress for hosts, causing long-lasting impact. Although host changes in morphological and reproductive traits due to parasitism are well known, shifts in their physiological system, altering metabolite concentrations, are less known due to the difficulty of quantification. Here, we use ecometabolomic techniques in the plant–plant interaction, comparing the complete metabolome of the leaves from mistletoe (Viscum album) and needles from their host (Pinus nigra), both parasitized and unparasitized, to elucidate host responses to plant parasitism. Our results show that mistletoe acquires metabolites basically from the primary metabolism of its host and synthesizes its own defence compounds. In response to mistletoe parasitism, pines modify a quarter of their metabolome over the year, making the pine canopy metabolome more homogeneous by reducing the seasonal shifts in topdown stratification. Overall, host pines increase antioxidant metabolites, suggesting oxidative stress, and also increase part of the metabolites required by mistletoe, which act as a permanent sink of host resources. In conclusion, by exerting biotic stress and thereby causing permanent systemic change, mistletoe parasitism generates a new host-plant metabolic identity available in forest canopy, which could have notable ecological consequences in the forest ecosystem. 2021-10-15T06:42:08Z 2021-10-15T06:42:08Z 2021-09-06 info:eu-repo/semantics/article Lázaro-González, A... [et al.] (2021). Implications of mistletoe parasitism for the host metabolome: A new plant identity in the forest canopy. Plant, Cell & Environment, 1– 12. [https://doi.org/10.1111/pce.14179] http://hdl.handle.net/10481/70860 10.1111/pce.14179 eng info:eu-repo/grantAgreement/EC/FP7/610028 http://creativecommons.org/licenses/by-nc/3.0/es/ info:eu-repo/semantics/openAccess Atribución-NoComercial 3.0 España Wiley-Blackwell Publishing