Figure 3.

Effect of plant age and organ (roots or leaves) on M. maydis extracellular laccase activity: The laccase test was performed, as described in the legend of Figure 1. The experiment conditions are described in the legend of Figure 2. Maize plants’ powder from plants aged 23 and 43 days (designated young and mature, respectively) was added to MM without glucose. The resulting growth medium was incubated with ABTS for 10 min. The enzymatic units (U) were defined as the amount of enzyme oxidizing 1 µmol ABTS in 1 min at 28 ± 1 °C in the dark. The values represent an average of 4–6 repetitions with the exception of the control (minimal medium only), which included two repetitions. Each repeat consists of the entire roots or leaves of one plant. Levels not connected by the same letter (A, B, C, and D) are significantly different (p < 0.05, ANOVA). The insert is a representative photo of the experiment treatments after 30 min of incubation.