Biological Activity of a Phytotoxic Glycopeptide Produced by Corynebacterium sepedonicum.

A purified toxic glycopeptide from Corynebacterium sepedonicum (Speick.) Dows., possesses the capacity to wilt plant cuttings. The toxin induces a rapid general flaccidity in stem tissues followed by a leaf wilt making its effects significantly different from that induced by high molecular weight substances (dextrans). In the latter case, the initial effect of a dextran induced wilt is a leaf wilt presumably caused by the plugging of xylem elements. However, physiological experiments including dye transport studies, plasmolytic studies, measurements on electrolytes, studies on the movement of (3)H(2)O through tomato cuttings, and toxin binding studies all strongly suggest that the primary effect of the toxin is to destroy the integrity of cellular membranes resulting in the net loss of water from the cell. Membrane damage in toxin treated plants was confirmed by electron microscopic observations. Evidence of damage were seen in chloroplasts, mitochondria, the plasma membrane, and the structural integrity of the cell wall. These effects appeared to be a direct cause and not a secondary result of the toxin as shown by autoradiographic studies using (3)H-toxin.