Fig. 3. Histochemical staining of GUS enzymatic activity in 7‐d‐old seedlings following transfer to vertically positioned plates with solid medium containing 5 mm caffeine for 24 h. GUS activity was found in: A, GTR81, shoot apex, leaf primordia and hypocotyl vasculature; B, GTR150, lateral root primordia; C, GTR404, induced throughout root except the tip; D, GTR424, cotyledon and root vasculature; E, ETR414, induced throughout cotyledons; F, GTR426, cotyledon vasculature; G, ETR528, cotyledons and stipules, induced ubiquitously by caffeine treatment.