Overexpression of NfsI in switchgrass improved the uptake rate of 2,4-DNT
A liquid culture system was employed to examine uptake of 2,4-DNT by theNfsI overexpressing transgenic switchgrass plants. We chose 20 mg·L-12,4-DNT as the initial concentration based on the previous 2,4-DNT tolerance analysis in wild type switchgrass. The culture medium containing 20 mg·L-1 2,4-DNT without switchgrass plants was used as a blank control. After 2 days, the control switchgrass plants removed 24.9% of 2,4-DNT from the culture medium, whereas NfsI_OE-02 and -14 transgenic lines removed 66.7% and 64.3% of 2,4-DNT from the culture medium, respectively (Fig. 5A ). After 6 days, the control switchgrass plants removed 56.3% of 2,4-DNT from the culture medium (Fig. 5A ). However, they displayed serious symptoms of toxicity including growth stunting and leaf wilting, which prevented further removal of 2,4-DNT (Fig. S5A ). In contrast, 94.1% of 2,4-DNT was taken up by the transgenic switchgrass plants after 6 days (Fig. 5A ). Moreover, their growth was barely affected by 2,4-DNT treatment (Fig. S5B ). In addition, we compared the uptake rate of DNTS between control and transgenic switchgrass plants (Fig. 5B ). Our results showed that overexpressing NfsI in switchgrass did not improve the uptake rate of DNTS.