Toxicity and translocation of graphene oxide in Arabidopsis thaliana

We investigated the possible safety property and translocation of graphene oxide (GO) in the range of μg/L in Arabidopsis. GO exposure did not obviously influence germination, seed development, shoot and root development of seedlings, and flowering time. Meanwhile, GO exposure could not induce severe H2O2 production, increase in malondialdehyde content, formation of oxidative stress, and altered activities of antioxidant enzymes. Moreover, GO exposure did not change expression patterns of examined genes required for germination, photomorphogenesis, root development, and transition from vegetative to reproductive development. In the seedling, we did not observe severe GO accumulation in mesophyll and parenchyma cells of leaf or stem, and in sieve element in leaf, stem, or root. In contrast, we observed the severe GO accumulation in root hair and root parenchyma cells. Our results provide the physiological basis for safety property of GO at the examined concentrations in Arabidopsis plants. Furthermore, our data imply that although GO was absorbed by Arabidopsis plants through root hairs, plants might still have strong ability to be against GO translocation into stem or leaves. In addition, we found that cotyledon might serve as an important site for GO distribution during the early development.