Fig. 1.

Biological activity of purified cellulase CelC2 from R. leguminosarum bv trifolii ANU843 on clover root hairs. (A–C) Nomarski interference contrast micrographs. (A) Typical control root hair without enzyme treatment. (B) Early stage in expression of the Hot phenotype. A portion of the root hair protoplast (arrow) has extruded through the hole made at the tip of the root hair wall by CelC2. (C) Further extrusion of a larger portion of the protoplast (arrow) through the hole made by CelC2 cellulase at a root-hair tip. (D–H) Phase-contrast micrographs. (D and E) The refractile hole (arrow) made by CelC2 cellulase at the tip of a clover root hair after its cytoplasm has already been expelled into the external rooting medium. (F and G) Alfalfa root hairs remain intact in the untreated control (F) and after incubation with CelC2 from ANU843 (G). (H) Extensive degradation of clover root hairs after treatment with a commercial fungal cellulase. (Scale bar: 12 μm.)