1H NMR and GC-MS Based Metabolomics Revealed Defense and Detoxification Mechanism of Cucumber Plants under Nano-Cu Stress

Oral Presentation

Prepared by L. Zhao1, H. Yuxiong2, J. Hu3, A. Keller4
1 - University of California, Santa Barbara, Bren Hall, Isla Vista, Santa Barbara, CA, 03117, United States
2 - Bren School of Environmental Science & Management, University of California, Santa Barbara, CA, 93106-5131, United States
3 - University of California Center for Environmental Implications of Nanotechnology, , Santa Barbara, CA, 93106-5131, United States
4 - aterials Research Laboratory, University of California, Santa Barbara, CA, 93106-5131,

Contact Information: andrewlijuan@gmail.com; 805-689-9457


Nano-Cu is organic pesticide and is regarded as less toxic compared to traditional pesticides. However, with the continuous accumulation in soil, concerns about their toxicity and bioaccumulation in crop plants have been raised. Root exudates, as hidden part of plant defense, have been underestimated and less reported. In this study, two-week-old cucumber plants were cultivated in a hydroponic system were exposed to 0, 10 mg/L and 20 mg/L nano-Cu for one week. The root exudates profiling were evaluated by Gas Chromatography-Mass Spectrometry (GC-MS) based metabolomics. Changes in mineral nutrient metabolism induced by nano-Cu were determined by ICP-MS. Results showed that nano-Cu at both concentrations interfere with the uptake of a number of micro- and macro-nutrients, such as Na, P, S, Mo, Zn, and Fe. Metabolomics results showed totally 11 amino acids in root exudates have been up-regulated by nano-Cu. The secreted amino acids are possibly acting as chelating agent with Cu ions/nano Cu and hindering its translocate to upper part tissues. In addition, the level of two secondary metabolites salicylic acid and benzoic acids, which play an important role in stress defense, were significantly increased by nano-Cu. Threonic acid, a byproduct of ascorbic acids, was up-regulated by nano-Cu, indicating reactive oxygen species (ROS) has been triggered and oxidative stress occurred in the rhizosphere. Thus, we demonstrate that non-targeted GC-MS based metabolomics on root exudate profiling is a powerful tool to uncover the stress response and detoxification mechanism of cucumber plants to nano-Cu.