A Role of Phytotoxin in Virulence of Pseudomonas glumae Kurita et Tabei.

Abstract

The relationship between the phytotoxin (C7H7N5O2) produced by Pseudomonas glumae and its virulence was studied. All of the phytotoxin productive strains were virulent to rice plants with a few exception, whereas all the phytotoxin non-productive strains were avirulent. A striking difference in the time course of phytotoxin production was observed between virulent strains and avirulent strains of P. glumae. The phytotoxin inhibited elongation of sprouts and roots of rice seedlings almost completely at 10 microgram/ml. Rice panicles,which were treated with the phytotoxin at concentrations of 2.5 or 25 microgram/ml by dipping for 10 min at the flowering stage, produced a brown band on the palea and lemmaa, a characteristic symptom of the bacterial grain rot of rice. The phytotoxin was isolated not only from culture filtrates, but also from rice seedlings infected with P. glumae. These results suggest that the phytotoxin produced by P. glumae will be closely associated with its virulence