Rotihibins, novel plant growth regulators from Streptomyces graminofaciens.

In the course of screening search for plant growth regulators, a culture filtrate of Streptomyces graminofaciens 3C02 was found to inhibit the growth of lettuce seedlings. The active substances, named rotihibin A (1) and B (2), were revealed to be lipo-peptidal compounds. Rotihibins inhibit growth of various plants at below 1 microgram/ml, but do not show lethal activity even at higher doses.