Figure 4.

Inducible in vivo LUC activity conferred by the −258 to −45 and −147 to −45 TCH4 sequences in response to touch stimulation. Plants harboring −258 to −45 TCH4::LUC (A), −147 to −45 TCH4::LUC (B), or UBQ10::LUC (C) transgenes, were sprayed with 1 mm luciferin and 50 mm sodium citrate, pH 5.6, and allowed to absorb the substrate for 30 min. The plants were then placed in a low-light imager and an initial luminescence reading was obtained before stimulation. Control plants were left undisturbed, whereas others were touch stimulated by gently bending them back and forth 20 times. Fifteen-minute (A and B) or 5-min (C) luminescence readings were collected, and the data were extracted and analyzed with Excel (Microsoft, Redmond, WA). The graphs at the top represent the response profiles of individual plants. Traces of control plants are shown in blue; touch-stimulated plants are shown in red. Bottom, Computer-generated false-color overlays of the light emission at 45 min poststimulation. The color bar inset represents the dynamic range of light levels, where minimum light is indicated with dark blue and maximum light is shown in magenta. The transgenes assayed are represented by rectangles below each panel (not drawn to scale); see Figure 1 legend for details.