ISOLATION AND CHARACTERIZATION OF THAXTOMIN-TYPE PHYTOTOXINS ASSOCIATED WITH STREPTOMYCES-IPOMOEAE

Chromatographic investigations of Streptomyces ipomoeae infected potat o tissue and sweetpotato tissue yielded three compounds which on asept ically cultured minitubers individually reproduced symptoms typical of the common scab disease. Spectroscopic examination of the two minor c omponents elicited sufficient information to identify them as analogs of the major constituent which had been previously characterized as -m ethylcyclo-(L-4-nitrotryptophyl-L-phenylalanyl). Subsequent investigat ions of the infected tissue extracts identified a possible toxin precu rsor substance as 12-N-methylcyclo-(L-tryptophyl-L-phenylalanyl).