The Role of Graphene Oxide on Tobacco Root Growth and Its Preliminary Mechanism

To better understand the effects of nanomaterials on plants, tobacco seedlings and graphene oxide were used as research materials for detailed study. The tobacco seedlings were treated with 0 mg/L and 20 mg/L of graphene oxide. Results indicated that 20 mg/L of graphene oxide had a significant effect on the tobacco roots growth. Treatment with 20 mg/L of graphene oxide resulted into shorter seminal root length than control samples after 20 days treatment. Moreover, the numbers of adventitious roots were also dramatically increased in the treated samples when compared to the untreated ones after 35 days treatment, the increase being about two to three times more in the treated samples. The average weight of treated fresh plants' roots was 64.8 mg after 35 days treatment, which was 1.5 times as great as that of the untreated plants. Graphene oxide treatments also resulted into higher SOD, POD, and CAT activities, and also lower MDA content. The treatment with 20 mg/L of graphene oxide also resulted in the increased transcript levels of IAA3, IAA4, IAA7, ARF2, and ARF8, indicating that the graphene oxide treatment affected the gene transcript levels of the IAA relatives, resulting in enhanced roots' growth. However, the mechanism by which 20 mg/L of graphene improves part of roots' growth still needs further study.