title: The effect of glufosinate on nitrogen assimilation at the physiological, biochemical and molecular levels in Phaeodactylum tricornutum.
abstract: This study investigated the effects of glufosinate, a widely used herbicide, on the marine diatom Phaeodactylum tricornutum through short-term toxicity tests at the physiological and gene transcriptional levels. Glufosinate (4 mg L(-1)) decreased the amount of pigments but increased reactive oxygen species (ROS) and malondialdehyde levels. As a glutamine synthetase (GS) inhibitor, glufosinate affected the transcripts and activities of key enzymes related to nitrogen assimilation. Transcript levels of GS and nitrate reductase (NR) in P. tricornutum decreased to only 57 and 26 % of the control. However, transcript levels of nitrate transporter (NRT) and the small subunit of glutamate synthase (GltD) were 1.79 and 1.76 times higher than that of the control. The activities of NRT, GS and GOGAT were consistent with gene expression except for NR, which was regulated mainly by post-translational modification. Furthermore, the results of electron microscopy showed that chloroplast structure was disrupted in response to glufosinate exposure. These results demonstrated that glufosinate first disturbed nitrogen metabolism and caused a ROS burst, which disrupted chloroplast ultrastructure. Ultimately, the growth of P. tricornutum was greatly inhibited by glufosinate.
authors.affiliation: College of Biological and Environmental Engineering, Zhejiang University of Technology, Hangzhou, 310032, People's Republic of China.
authors.forename: Jun
authors.initials: J
authors.lastname: Xie
authors.forename: Xiaocui
authors.initials: X
authors.lastname: Bai
authors.forename: Yali
authors.initials: Y
authors.lastname: Li
authors.forename: Chongchong
authors.initials: C
authors.lastname: Sun
authors.forename: Haifeng
authors.initials: H
authors.lastname: Qian
authors.forename: Zhengwei
authors.initials: Z
authors.lastname: Fu
mesh_terms: D000613:Aminobutyrates / Q000633:toxicity*; D027321:Anion Transport Proteins / Q000378:metabolism; D002736:Chloroplasts / Q000473:pathology / Q000648:ultrastructure; D017377:Diatoms / Q000187:drug effects* / Q000378:metabolism; D005974:Glutamate-Ammonia Ligase / Q000378:metabolism; D008315:Malondialdehyde / Q000032:analysis / Q000378:metabolism; D050901:Nitrate Reductase / Q000378:metabolism; D000091285:Nitrate Transporters; D009566:Nitrates / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism*; D010860:Pigments, Biological / Q000032:analysis; D017382:Reactive Oxygen Species / Q000032:analysis; D023382:Toxicity Tests, Acute; D014158:Transcription, Genetic
chemical_list: D000613:Aminobutyrates; D027321:Anion Transport Proteins; D000091285:Nitrate Transporters; D009566:Nitrates; D010860:Pigments, Biological; D017382:Reactive Oxygen Species; D008315:Malondialdehyde; C003121:phosphinothricin; D050901:Nitrate Reductase; D005974:Glutamate-Ammonia Ligase; D009584:Nitrogen