Benzo[a]pyrene induced lipid changes in the monoxenic arbuscular mycorrhizal chicory roots

Abstract

Arbuscular mycorrhizal (AM) colonization may be one of the means that protects plants and allows them to thrive on polycyclic aromatic hydrocarbon-polluted soils including the carcinogenic benzo(a)pyrene (B[a]P). To understand the mechanisms involved in the AM symbiosis tolerance to B[a]P toxicity, the purpose of this study was to compare the lipid compositions as well as the contents between mycorrhizal and non-mycorrhizal chicory root cultures grown in vitro under B[a]P pollution. Firstly, B[a]P induced significant decreases of the Glomalean lipid markers: C16:1ω5 and 24-methyl/methylene sterol amounts in AM roots indicating a reduced AM fungal development inside the roots. Secondly, whereas increases in fatty acid amounts after B[a]P application were measured in non-mycorrhizal roots, no changes were shown in mycorrhizal roots. On the other hand, while, after treatment with B[a]P, the total phospholipid contents were unmodified in non-mycorrhizal roots in comparison with the control, drastic reductions were observed in mycorrhizal roots, mainly owing to decreases in phosphatidylethanolamine and phosphatidylcholine. Moreover, B[a]P affected AM root sterols by reducing stigmasterol. In conclusion, the findings presented in this paper have highlighted, for the first time, significant changes in the AM root lipid metabolism under B[a]P pollution and have culminated on their role in the defense/protection mechanisms.