Fig. 7

Expression analysis of SlPT4 promoter activity in cotransformed mycorrhized tomato hairy roots after GUS staining. GUS activity in A. rhizogenes-transformed roots expressing the SlPT4 promoter β-glucuronidase fusion was assessed 45 days after inoculation with R. irregularis (b–d), and without R. irregularis (a). GUS stained roots were vibratome sectioned (d–f) and the AM fungus was counterstained with WGA-Alexa Fluor488 to visualize fungal structures (e, f). Root cells with GUS activity (SlPT4 promoter expression marker) observed under bright-field (e) are coincident to cells containing arbuscules, which deliver green fluorescence due to AM hyphae staining with WGA-Alexa Fluor488 (f). Asterisks indicate arbuscules in the host cortical cells. All images were taken with an inverted fluorescent microscope, except in b, which was taken with a stereomicroscope