Overwhelming use of engineered nanoparticles demands rapid assessment of their environmental impacts. The transport of cerium oxide nanoparticles (nCeO(2)) in plants and their impact on cellular homeostasis as a function of exposure duration is not well understood. In this study, kidney bean plants were exposed to suspensions of similar to 8 +/- 1 nm nCeO(2) (62.5 to 500 mg/L) for 15 days in hydroponic conditions. Plant parts were analyzed for cerium accumulation after one, seven, and 15 days of nCeO(2) exposure. The primary indicators of stress like lipid peroxidation, antioxidant enzyme activities, total soluble protein and chlorophyll contents were studied. Cerium in tissues was localized using scanning electron microscopy and synchrotron mu-XRF mapping, and the chemical forms were identified using mu-XANES. In the root epidermis, cerium was primarily shown to exist as nCeO(2), although a small fraction (12%) was biotransformed to Ce(III) compound. Cerium was found to reach the root vascular tissues and translocate to aerial parts with time. Upon prolonged exposure to 500 mg nCeO(2)/L, the root antioxidant enzyme activities were significantly reduced, simultaneously increasing the root soluble protein by 204%. In addition, leaf's guaiacol peroxidase activity was enhanced with nCeO(2) exposure in order to maintain cellular homeostasis. (C) 2014 Elsevier B.V. All rights reserved.