Studies of the root nodules of leguminous plants IV: Production of indole acetic acid by a bradyrhizobium sp. from the root nodules of a leguminous shrub, crotalaria retusa L

Abstract

AbstractBradyrhizobium sp. isolated from the root nodules of a leguminous shrub, Crotalaria retusa L., produced a high amount of indole acetic acid (IAA) from tryptophan in the culture. The bacteria preferred D‐isomer to the DL‐ or L‐isomer of tryptophan for the IAA production. The IAA production could be increased up to 153.6% over control by supplementing the medium with arabinose (0.5%), ZnSO4(0.01 μg/ml), KNO3 (0.1%), thiamine‐HCl (0.01 μg/ml) and EDTA (5 μg/ml).The possible role of the rhizobial production of IAA with the rhizobia‐legume symbiosis is discussed.