AUXIN-INDUCED RELEASE OF CELLULOLYTIC ACTIVITY FROM RHIZOBIA AND THE PROMOTION OF EFFECTS OF THIS ACTIVITY ON ROOT HAIR CURLING IN AVENA-SATIVA

Rhizobium leguminosarum biovar viciae 128C53 induces root hair curling in its host pea plant (Pisum sativum L.), but not in non-host plants. However, R. I. viciae 128C53 pre-incubated with 2,4-dichlorophenoxyac etic acid (2,4-D), induced curling in oat (Avena sativa L.), a monocot yledonous non-host plant. Cellulolytic activity was detected in the me dium after cultivation of the rhizobia with 2,4-D, but less after cult ivation without 2,4-D. Authentic cellulase supplied exogeneously stimu lated the root hair curling at low concentration (0.01% w/v). These re sults suggest that cellulase was secreted from R. I. viciae 128C53 and induced curling when rhizobia were treated with 2,4-D. Other cell wal l decomposing enzymes, hemicellulase and pectinase, may co-operate wit h cellulase in the curling of root hairs.