FNOCT as a fluorescent probe for in vivo localization of nitric oxide distribution in tobacco roots

► FNOCT 8a specifically and efficiently detects fluorescence due to nitric oxide in intact tobacco roots. ► Methylene blue is more effective in scavenging NO as compared to cPTIO. ► NaNO2 enhances NO production at the root tips. ► NaNO3 inhibits NO formation in the roots.