Antibiotic Effects of Four Exogenous Phenolic Acids on Soilborne Pathogen, Cylindrocarpon destructans

Abstract

Cylindrocarpon root rot caused by Cylindrocarpon destructans is a serious disease on ginseng (Panax ginseng) in northeast China. Some allelochemicals (phenolic acids) from root exudates and decaying residues of ginseng plant may be related to Cylindrocarpon root rot. The antibiotic effects of phenolic acids on Cylindrocarpon destructans were studied to investigate the relationships between the phenolic acids and the fungus in the plant-microbe interaction. Results show that the hyphal growth of C. destructans was inhibited by salicylic, cinnamic and benzoic acid. At the highest concentration (1600 μg ml-1) of salicylic and cinnamic acid, the colony diameter of C. destructans decreased by 32.47% and 23.78%, respectively. C. destructans growth was powerfully repressed by benzoic acid in a concentration-dependent manner. However, activities of phytopathogenic enzymes (pectinase and cellulase) were greatly stimulated by the phenolic acids. It was concluded that phenolic acids inhibited the growth of C. destructans but dramatically stimulated activities of hydrolytic enzymes of C. destructans.