Figure 5. Effects of plant growth and development on CCT activity in situ.

Each in-situ assay was performed on 50 mg of native or heat-denatured, blot-dried epidermis, with 0.14–0.75 kBq [³H]HHA in 300 µl pH 5.5 buffer at 20°C for 24 h. In a, b and d, the CCT products (ester-bonded radioactivity detected in extract f; Figure 2) were assayed. In c, total methanol-insolubilised products (residue B; Figure 2) are reported. (a) Epidermis samples from differently aged, expanding Hylotelephium leaves; 0.72 kBq [³H]HHA. Bars indicate standard errors (n = 3). (b) Epidermis samples from expanding versus fully expanded Hylotelephium leaves; 0.15 kBq [³H]HHA. Bars indicate range (n = 2). (c) Epidermis samples from tomato fruit (cv. Ailsa Craig) at different developmental stages; 0.14 kBq [³H]HHA. Bars indicate range (n = 2). At 7–28 days after anthesis, the fruit are expanding; thereafter they are described [90] as MG, mature green (growth stopped); BR, breaker (10% colour change); TR, turning (30% colour change), OR, orange; LR, light red; DR, deep red. (d) Epidermis samples from etiolated pea epicotyls; 0.69 kBq [³H]HHA. Bars indicate standard errors (n = 3).