title: Role of brassinosteroids in alleviation of phenanthrene-cadmium co-contamination-induced photosynthetic inhibition and oxidative stress in tomato.
abstract: Heavy metal pollution often occurs together with organic contaminants. Brassinosteroids (BRs) induce plant tolerance to several abiotic stresses, including phenanthrene (PHE) and cadmium (Cd) stress. However, the role of BRs in PHE+Cd co-contamination-induced stress amelioration is unknown. Here, the interactive effects of PHE, Cd, and 24-epibrassinolide (EBR; a biologically active BR) were investigated in tomato plants. The application of Cd (100 µM) alone was more phytotoxic than PHE applied alone (100 µM); however, their combined application resulted in slightly improved photosynthetic activity and pigment content compared with Cd alone after a 40 d exposure. Accumulation of reactive oxygen species and membrane lipid peroxidation were induced by PHE and/or Cd; however, the differences in effect were insignificant between Cd and PHE+Cd. The foliar application of EBR (0.1 µM) to PHE- and/or Cd-stressed plants alleviated photosynthetic inhibition and oxidative stress by causing enhancement of the activity of the enzymes and related transcript levels of the antioxidant system, secondary metabolism, and the xenobiotic detoxification system. Additionally, PHE and/or Cd residues were significantly decreased in both the leaves and roots after application of EBR, more specifically in PHE+Cd-stressed plants when treated with EBR, indicating a possible improvement in detoxification of these pollutants. The findings thus suggest a potential interaction of EBR and PHE for Cd stress alleviation. These results advocate a positive role for EBR in reducing pollutant residues for food safety and also strengthening phytoremediation.
authors.affiliation: Department of Horticulture, Zijingang Campus, Zhejiang University, Yuhangtang Road 866, Hangzhou 310058, People's Republic of China. abammed@zju.edu.cn
authors.forename: Golam Jalal
authors.initials: GJ
authors.lastname: Ahammed
authors.forename: Sikander Pal
authors.initials: SP
authors.lastname: Choudhary
authors.forename: Shuangchen
authors.initials: S
authors.lastname: Chen
authors.forename: Xiaojian
authors.initials: X
authors.lastname: Xia
authors.forename: Kai
authors.initials: K
authors.lastname: Shi
authors.forename: Yanhong
authors.initials: Y
authors.lastname: Zhou
authors.forename: Jingquan
authors.initials: J
authors.lastname: Yu
mesh_terms: D000975:Antioxidants / Q000378:metabolism; D001673:Biodegradation, Environmental / Q000187:drug effects; D018533:Biomass; D060406:Brassinosteroids / Q000494:pharmacology*; D002104:Cadmium / Q000633:toxicity*; D002734:Chlorophyll / Q000378:metabolism; D004787:Environmental Pollution / Q000032:analysis*; D005453:Fluorescence; D005740:Gases / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D006861:Hydrogen Peroxide / Q000378:metabolism; D008658:Inactivation, Metabolic / Q000235:genetics; D015227:Lipid Peroxidation / Q000187:drug effects; D018551:Solanum lycopersicum / Q000187:drug effects / Q000201:enzymology / Q000235:genetics / Q000502:physiology*; D018384:Oxidative Stress / Q000187:drug effects*; D010616:Phenanthrenes / Q000633:toxicity*; D010788:Photosynthesis / Q000187:drug effects*; D018515:Plant Leaves / Q000187:drug effects / Q000201:enzymology; D013260:Steroids, Heterocyclic / Q000494:pharmacology; D013481:Superoxides / Q000378:metabolism
chemical_list: D000975:Antioxidants; D060406:Brassinosteroids; D005740:Gases; D010616:Phenanthrenes; D013260:Steroids, Heterocyclic; D002104:Cadmium; D013481:Superoxides; D002734:Chlorophyll; C031181:phenanthrene; D006861:Hydrogen Peroxide; C023623:brassinolide