UTILIZATION BY TOMATOES OF IRON MEDIATED BY A SIDEROPHORE PRODUCED BY RHIZOPUS-ARRHIZUS

Rhizonus arrhizus was found to produce a novel siderophore named raphorin (Ra) when grown under Fe deficiency. Partially purified Fe-Ra was found to alleviate Fe deficiency when applied to tomato plants grown in nutrient solutions buffered by either CaCO3 (pH 7.3) or HEPES (pH 7). Iron (Fe-55) uptake rate by plants mediated by Ra, and translocation rate to the shoot, was almost as high as from (FeEDDHA)-Fe-55. It has been concluded the Fe-Ra is a most efficient Fe source for plants when compared to other microbial siderophores.