Figure 4. Changes in enzyme activity by fungal associate and treatment.

N-acetyl-glucosaminidase activity was elevated for Rhizopogon occidentalis-associated root tips when in isolation relative to competition with Suillus pungens (C). β-xylosidase and acid phosphatase activities were elevated for Thelephora terrestris-associated tips when in competition with R. occidentalis (D–E). Bar heights indicate means across root tips within a treatment group (measured in pmol mm⁻² min⁻¹); whiskers give standard error. Letters indicate statistically significant differences in mean within species by treatment (Tukey’s HSD, P < 0.05). Colors represent treatments: red, R. occidentalis; yellow, S. pungens; and blue, T. terrestris; color blends represent species combinations (e.g., green, S. pungens + T. terrestris).