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.

Identification of the QTL underlying the vitamin E content of soybean seeds

“…Tocopherols have been detected in leaves, seeds, roots, tubers, fruits, stems, hypocotyls, cotyledons of higher plants and the xylem of woody plants (Buring and Hennekens , Munne‐Bosch and Alegre , Fleta‐Soriano et al. ). VE was synthesized in photosynthetic organisms such as plants, algae and some cyanobacteria (Mene and Della ).…”

“…The four different forms of tocopherols and tocotrienols (a-, b-, cand d-forms) differ from one another in the number and location of methyl groups. Tocopherols have been detected in leaves, seeds, roots, tubers, fruits, stems, hypocotyls, cotyledons of higher plants and the xylem of woody plants (Buring and Hennekens 1997, Munne-Bosch and Alegre 2002, Fleta-Soriano et al 2014. VE was synthesized in photosynthetic organisms such as plants, algae and some cyanobacteria (Mene and Della 2010).…”