Production of the Soybean-Chlorosis Toxin by Rhizobium japonicum in Pure Culture.

Rhizobial-induced chlorosis in soybeans (Glcine uinax.) is caused by a phytotoxin produced in the nodules of the affected plants (1, 4). The phytotoxin has been isolated from nodules and partially characterized as a low molecular-weight amino compound (3). In the previous paper we reported finding an unidentified amino acid (unknown Y) in soybean nodules, the metabolism of which appeared to be somewhat related to that of the toxin. Although production of the 2 compounds in the nodule was associated with certain strains of Rhi4obimni japonicumin, it was not established whether the rhizobia or the host was actually synthesizing either or both of the compounds. In this paper we report that both the phytotoxin and unknown Y can be synthesized by Rhi-obium in pure culture, and we describe methods for relatively large-scale production and isolation of both compoullds.