Fig. 4. Effect of 2,4-DNT on root length and ROS content of control and transgenic switchgrass plants. (A) Root length of the control and transgenic switchgrass plantlets were measured after 2,4-DNT treatment. (B) In situ detection of ROS in roots of control and transgenic switchgrass plantlets by DAB staining. (C) ROS content in roots of the control and transgenic switchgrass plantlets were measured after 2,4-DNT treatment. The control and transgenic (NfsI_OE-02 and -14) switchgrass plantlets were exposed to 0, 2, and 20 mg·L-1 2,4-DNT. After 14 days of treatment, the photographs of roots stained with NBT were taken. Root length as well as ROS content were also measured. Each sample included six vegetatively propagated copies. Values are mean ± SE (n = 3).