Induction of adventitious roots by culture filtrates of the hairy root bacterium, Agrobacterium rhizogenes

Abstract

Cell-free culture filtrates of Agrobacterium rhizogenes significantly increased adventitious root initiation in a mung bean hypocotyl bioassay. These filtrates were most active from cultures at their maximum cell density; the root-inducing activity declined rapidly after this time. The contents of cells disrupted by sonification were not active nor did they increase the activity of a 6-day-old culture filtrate. The root-inducing factor was heat stable, apparently dialyzable, and antagonized by kinetin. The 3-indole-acetic acid concentration of the culture filtrates was not high enough to account for the number of roots formed.