title: Tocochromanols in wood: a potential new tool for dendrometabolomics.
abstract: Tocochromanols are the most abundant lipid-soluble antioxidants in plants. Among them, α-tocopherol (α-Toc) shows a particularly high sensitivity to environmental stressors and its content is used as a stress biomarker even in non-photosynthetic tissues. Nevertheless, the presence of tocochromanols has not been described yet in the xylem of woody plants, even when their functions regarding cell membrane protection and the transport of photoassimilates may be crucial in this tissue and despite its potential utility in dendrometabolomics. Considering all these, we aimed to determine the presence and distribution of tocochromanols in the xylem of woody plants, to examine their responsiveness to high temperature and to evaluate their potential as environmental bioindicators. The analysis of 29 phyllogenetically diverse species showed that α-Toc is the most abundant and frequent tocochromanol in the xylem and is ubiquitously present in all the studied species, with a concentration ranging from 0.5 to 39.3 μg g(-1) of dry weight. α-Tocopherol appeared to be mainly located in the parenchyma rays and was found in both the sapwood and the heartwood, suggesting that it is present even in dead parenchyma cells. The levels of α-Toc in the xylem did not change in response to locally induced xylem heating, but responded positively to the 3-year moving average of annual precipitation. The present findings suggest that α-Toc may be linked to changes in climatic stress. This should enhance further research on the environmental controls of α-Toc variation in the xylem as a first step towards a deeper understanding of dendrometabolomics.
authors.affiliation: Departament of Plant Biology and Ecology, University of the Basque Country (UPV/EHU), Apdo 644, E-48080 Bilbao, Spain.
authors.forename: Eva
authors.initials: E
authors.lastname: Fleta-Soriano
authors.affiliation: Departament of Plant Biology and Ecology, University of the Basque Country (UPV/EHU), Apdo 644, E-48080 Bilbao, Spain Institute of Botany and Center for Molecular Biosciences Innsbruck, University of Innsbruck, Sternwartestraße 15, Innsbruck A-6020, Austria beatriz.fernandezm@ehu.es.
authors.forename: Beatriz
authors.initials: B
authors.lastname: Fernández-Marín
authors.affiliation: Departamento de Ciencias Agroforestales, EU de Ingenierías Agrarias, Universidad de Valladolid, Los Pajaritos s/n, E-42004 Soria, Spain.
authors.forename: José Miguel
authors.initials: JM
authors.lastname: Olano
authors.affiliation: Departament of Plant Biology and Ecology, University of the Basque Country (UPV/EHU), Apdo 644, E-48080 Bilbao, Spain.
authors.forename: Fátima
authors.initials: F
authors.lastname: Míguez
authors.affiliation: Departament of Plant Biology and Ecology, University of the Basque Country (UPV/EHU), Apdo 644, E-48080 Bilbao, Spain.
authors.forename: Jon
authors.initials: J
authors.lastname: Molinero
authors.affiliation: Instituto Pirenaico de Ecología (IPE-CSIC), Avda Montañana 1005, E-50192 Zaragoza, Spain.
authors.forename: Jesús Julio
authors.initials: JJ
authors.lastname: Camarero
authors.affiliation: Departament of Plant Biology and Ecology, University of the Basque Country (UPV/EHU), Apdo 644, E-48080 Bilbao, Spain.
authors.forename: José Ignacio
authors.initials: JI
authors.lastname: García-Plazaola
mesh_terms: D000222:Adaptation, Physiological; D000975:Antioxidants / Q000378:metabolism; D001692:Biological Transport; D002980:Climate; D057231:Climate Change; D055864:Droughts; D006358:Hot Temperature; D011891:Rain; D013312:Stress, Physiological; D014197:Trees / Q000378:metabolism*; D014867:Water; D014934:Wood / Q000378:metabolism*; D052584:Xylem; D024502:alpha-Tocopherol / Q000378:metabolism*
chemical_list: D000975:Antioxidants; D014867:Water; D024502:alpha-Tocopherol
keywords: heartwood; sapwood; tocopherol; tree ring; xylem