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Metabolomics to Detect Response of Lettuce (Lactuca sativa) to Cu(OH)2 Nanopesticides: Oxidative Stress Response and Detoxification Mechanisms
journal contribution
posted on 2016-08-02, 00:00 authored by Lijuan Zhao, Cruz Ortiz, Adeyemi
S. Adeleye, Qirui Hu, Hongjun Zhou, Yuxiong Huang, Arturo A. KellerThere
has been an increasing influx of nanopesticides into agriculture
in recent years. Understanding the interaction between nanopesticides
and edible plants is crucial in evaluating the potential impact of
nanotechnology on the environment and agriculture. Here we exposed
lettuce plants to Cu(OH)2 nanopesticides (1050–2100
mg/L) through foliar spray for one month. Inductively coupled plasma-mass
spectrometry (ICP-MS) results indicate that 97–99% (1353–2501
mg/kg) of copper was sequestered in the leaves and only a small percentage
(1–3%) (17.5–56.9 mg/kg) was translocated to root tissues
through phloem loading. Gas chromatography-time-of-flight mass spectrometry
(GC-TOF-MS) based metabolomics combined with partial least squares-discriminant
analysis (PLS-DA) multivariate analysis revealed that Cu(OH)2 nanopesticides altered metabolite levels of lettuce leaves. Tricarboxylic
(TCA) cycle and a number of amino acid-related biological pathways
were disturbed. Some antioxidant levels (cis-caffeic acid, chlorogenic
acid, 3,4-dihydroxycinnamic acid, dehydroascorbic acid) were significantly
decreased compared to the control, indicating that oxidative stress
and a defense response occurred. Nicotianamine, a copper chelator,
increased by 12–27 fold compared to the control, which may
represent a detoxification mechanism. The up-regulation of polyamines
(spermidine and putrescine) and potassium may mitigate oxidative stress
and enhance tolerance. The data presented here provide a molecular-scale
perspective on the response of plants to copper nanopesticides.