title: Brassinosteroids induce plant tolerance against phenanthrene by enhancing degradation and detoxification in Solanum lycopersicum L.
abstract: Polycyclic aromatic hydrocarbons (PAHs) are toxic to both plants and animals. The enhancement of plant tolerance and detoxification capacity is important for the plant-based remediation of PAHs. Therefore, we investigated the effects of 24-epibrassinolide (EBR) on the metabolism of a three-ringed PAH (phenanthrene-PHE) and subsequent stress tolerance in tomato (Solanum lycopersicum L.) plants. Exposure to PHE (300 μM) for 21 d significantly decreased biomass and net CO(2) assimilation (P(n)) but induced photoinhibition, malondialdehyde (MDA), H(2)O(2) and antioxidant enzymes. Obvious ultrastructural alterations were observed in the PHE-treated root tip cells. Importantly, the foliar application of EBR (0.1 μM) significantly increased biomass, P(n) and antioxidant enzyme activities but decreased MDA and H(2)O(2) compared with PHE alone and saved the root cells from severe damage. The expression of detoxification genes (CYP90b3, GSH1, GST1), reduced glutathione (GSH) content and glutathione S-transferase activity in the EBR+PHE-treated plants were higher than those of PHE alone. Additionally, lower levels of PHE residues in the roots were observed as a result of EBR+PHE treatment. Taken together, our results strongly suggest an enhanced and coordinated detoxification and degradation of PHE by EBR.
authors.affiliation: Department of Horticulture, Zijingang Campus, Zhejiang University, Yu Hang Tang Road 866, Hangzhou 310058, PR China.
authors.forename: Golam Jalal
authors.initials: GJ
authors.lastname: Ahammed
authors.forename: Chun-Juan
authors.initials: CJ
authors.lastname: Gao
authors.forename: Joshua Otieno
authors.initials: JO
authors.lastname: Ogweno
authors.forename: Yan-Hong
authors.initials: YH
authors.lastname: Zhou
authors.forename: Xiao-Jian
authors.initials: XJ
authors.lastname: Xia
authors.forename: Wei-Hua
authors.initials: WH
authors.lastname: Mao
authors.forename: Kai
authors.initials: K
authors.lastname: Shi
authors.forename: Jing-Quan
authors.initials: JQ
authors.lastname: Yu
mesh_terms: D000222:Adaptation, Physiological; D001673:Biodegradation, Environmental; D060406:Brassinosteroids / Q000494:pharmacology*; D005978:Glutathione / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D018551:Solanum lycopersicum / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism* / Q000502:physiology; D008315:Malondialdehyde / Q000378:metabolism; D018517:Plant Roots / Q000378:metabolism; D011084:Polycyclic Aromatic Hydrocarbons / Q000378:metabolism*
chemical_list: D060406:Brassinosteroids; D011084:Polycyclic Aromatic Hydrocarbons; D008315:Malondialdehyde; D006861:Hydrogen Peroxide; D005978:Glutathione