title: Brassinosteroid alleviates polychlorinated biphenyls-induced oxidative stress by enhancing antioxidant enzymes activity in tomato.
abstract: Polychlorinated biphenyls (PCBs) are persistent organic pollutants often found in the atmosphere. Phytoremediation of airborne PCBs is an emerging new concept to minimize potential human exposure. However, effects of atmospheric PCBs on plant growth, photosynthesis and antioxidant defence system are poorly understood area. Brassinosteroids have been reported to alleviate different abiotic stresses including organic pollutants-induced stress. Hence, we studied the effects of PCBs and 24-epibrassinolide (EBR) on biomass accumulation, photosynthetic machinery and antioxidant system in tomato plants. PCBs (0.4, 2.0 and 10 μg/l) mist spray significantly decreased dry weight, photosynthesis, chlorophyll contents in a dose dependent manner. Both stomatal and non-stomatal factors were involved in PCBs-induced photosynthetic inhibition. Likewise, the maximal photochemical efficiency of PSII (Fv/Fm), the quantum efficiency of PSII photochemistry (Φ(PSII)) and photochemical quenching coefficient were increasingly decreased by various levels of PCBs, suggesting an induction of photoinhibition. Increased accumulation of H(2)O(2) and O(2)(-) accompanied with high lipid peroxidation confirmed occurrence of oxidative stress upon PCBs exposure. Meanwhile, antioxidant enzymes activity was decreased following exposure to PCBs. Foliar application of EBR (100 nM) increased biomass, photosynthetic capacity, chlorophyll contents and alleviated photoinhibition by enhancing Fv/Fm, Φ(PSII) and qP. EBR significantly decreased harmful ROS accumulation and lipid peroxidation through the induction of antioxidant enzymes activity. Our results suggest a protective role of EBR against PCBs stress which may strengthen phytoremediation approaches by enhancing plant tolerance.
authors.affiliation: Department of Horticulture, Zijingang Campus, Zhejiang University, Yu Hang Tang Road 866, Hangzhou 310058, PR China. abammed@zju.edu.cn
authors.forename: Golam Jalal
authors.initials: GJ
authors.lastname: Ahammed
authors.forename: Yi-Ping
authors.initials: YP
authors.lastname: Ruan
authors.forename: Jie
authors.initials: J
authors.lastname: Zhou
authors.forename: Xiao-Jian
authors.initials: XJ
authors.lastname: Xia
authors.forename: Kai
authors.initials: K
authors.lastname: Shi
authors.forename: Yan-Hong
authors.initials: YH
authors.lastname: Zhou
authors.forename: Jing-Quan
authors.initials: JQ
authors.lastname: Yu
mesh_terms: D000975:Antioxidants / Q000494:pharmacology*; D001673:Biodegradation, Environmental; D060406:Brassinosteroids / Q000378:metabolism*; D002734:Chlorophyll / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D015227:Lipid Peroxidation / Q000187:drug effects; D018551:Solanum lycopersicum / Q000187:drug effects* / Q000502:physiology; D018384:Oxidative Stress / Q000187:drug effects; D010788:Photosynthesis / Q000187:drug effects; D011078:Polychlorinated Biphenyls / Q000633:toxicity*; D012989:Soil Pollutants / Q000633:toxicity*
chemical_list: D000975:Antioxidants; D060406:Brassinosteroids; D012989:Soil Pollutants; D002734:Chlorophyll; D006861:Hydrogen Peroxide; D011078:Polychlorinated Biphenyls