Response at Genetic, Metabolic, and Physiological Levels of Maize (Zea mays) Exposed to a Cu(OH)2 Nanopesticide
2017
Zhao, Lijuan | Hu, Qirui | Huang, Yuxiong | Keller, Arturo A.
Nanopesticides are becoming more popular in modern agriculture to improve crop protection product efficacy. However, information on their implications for crop plants is needed. In this study, 3-week-old maize plants were exposed to different doses of Cu(OH)₂ nanopesticide (0, 10, and 100 mg) for 7 days via foliar application. Gene expression of 9 antioxidant-related enzymes (CAT1, POD1, GST1, SOD-1A, SOD-B, GPX, APX1, HSP1, PER1) was determined using a quantitative real-time polymerase chain reaction. Using gas chromatography time-of-flight mass spectrometry, levels of 12 low-molecular-weight antioxidant compounds were measured. Results showed that a dose of 100 mg of Cu(OH)₂ nanopesticide significantly decreased leaf chlorophyll content and biomass by 17–20%. In addition, potassium and phosphorus were up-regulated (14% and 13%, respectively) in response to this dose. Gene expression of POD1 and GST1 was significantly (p < 0.05) increased by 42.6% and 71.8%, respectively, at a dose of 10 mg, but declined at high dose (100 mg). Precursors of phenolic acids (phenylalanine and tyrosine), 4-hydroxycinnamic acid, and total phenolic content were significantly increased (24–122%) in response to 100 mg, indicating that phenolic acids may also play an important role in antioxidant defense. This study provides important information on maize plant responses to the Cu(OH)₂ nanopesticide at genetic, metabolic, and physiological levels and may be applied to other nanoparticle/plant interaction studies.
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