THE EFFECT OF ANTIBIOTICS ON INFECTION OF WHEAT BY XANTHOMONAS TRANSLUCENS

Abstract

Seedlings were grown in plexiglas culture vessels containing Shive's four-salt solution with trace elements added. Single antibiotics in various concentrations were added to the culture solution. Streptomycin and chloramphenicol increased the resistance of Thatcher wheat to infection by Xanthomonas translucens (S.J. & R.) Hagb., but additions of actidione (cycloheximide), griseofulvin, and neomycin failed to do so. The dry weight per plant was reduced by all of the antibiotics even when the antibiotic had no apparent effect on the rate or amount of disease development. The reduction in weight was least with neomycin and greatest with the higher concentrations of three forms of streptomycin tested. Chloramphenicol reduced dry weight appreciably even though infection was controlled. The induction of resistance appears to be closely related to phytotoxicity and to the sensitivity of the pathogen to the same antibiotic.