Fig. 6
Induction levels of nitrate-regulated genes are improved in VvNPF6.5 transgenic plants. The expression of NIA1 (a and b) and NiR (c and d) was analyzed by quantitative RT-PCR. Wild-type and overexpression lines were grown hydroponically for 24 days, after which they were treated with nitrate-free medium using NH4HCO3 as the nitrogen source for 4 days and then exposed to 10 mM NO3− for the indicated time. The relative expression level was calculated by normalizing to that in wild-type plants which exposed to 10 mM NO3− for 30 min. AtUBQ10 was used as the internal control. Values are means ± SD, n = 3. Asterisks indicate difference between wild type and overexpression lines at P < 0.05 (*) by Student’s t-test