Uptake, transport, distribution and Bio-effects of SiO(2) nanoparticles in Bt-transgenic cotton

BACKGROUND: SiO(2) nanoparticle is one of the most popular nanomaterial which has been used in various fields, such as wastewater treatment, environmental remediation, food processing, industrial and household applications, biomedicine, disease labeling, and biosensor, etc. In agriculture, the use of SiO(2) nanoparticles as insecticide, carriers in drug delivery, or in uptake and translocation of nutrient elements, etc., has been given attention. However, the effects of nanoparticles on plants have been seldom studied. In this work, the toxicity of SiO(2) nanoparticles and their uptake, transport, distribution and bio-effects have been investigated in Bt-transgenic cotton. METHODS: The phytotoxic effects of SiO(2) nanoparticles were exhibited in Bt-transgenic cotton with different SiO(2) concentrations of 0, 10, 100, 500 and 2000 mg.L(−1) for 3 weeks through dry biomasses, nutrient elements, xylem sap, enzymes activities, and hormone concentrations. The uptake and distribution of nanoparticles by the plants were confirmed using transmission electron microscopy (TEM). RESULTS: The SiO(2) nanoparticles decreased significantly the plant height, shoot and root biomasses; the SiO(2) nanoparticles also affected the contents of Cu, Mg in shoots and Na in roots of transgenic cotton; and SOD activity and IAA concentration were significantly influenced by SiO(2) nanoparticles. In addition, SiO(2) nanoparticles were present in the xylem sap and roots as examined by TEM showing that the SiO(2) nanoparticles were transported from roots to shoots via xylem sap. CONCLUSIONS: This is the first report of the transportation of SiO(2) nanoparticles via xylem sap within Bt-transgenic cotton. This study provides direct evidence for the bioaccumulation of SiO(2) nanoparticles in plants, which shows the potential risks of SiO(2) nanoparticles impact on food crops and human health.