Production of cell‐wall polysaccharide degrading enzymes in carrot root tissues infected by Mycocentrospora acerina.

Abstract

Mycocentrospora acerina, the causal agent of liquorice rot of carrot roots, produces several cell‐wall polysaccharide degrading enzymes in vitro. To assess the involvement of these enzymes in tissue invasion, the production and localization of pectin methylesterases, polygalacturonases, pectate lyases and endoglucanases were measured in root tissue infected by M. acerina. Isoelectrofocusing studies demonstrated the production of three isoforms of pectin methylesterase in healthy tissue. In infected tissue, two isoforms already observed in the culture filtrate and two novel isoforms were detected. Tissue maceration was associated with in vivo production of pectin methylesterase and polygalacturonase, which were first detected on the second day whereas pectate lyase and endoglucanase activities were detected only from the fourth day after infection. Maceration was always detected ahead of the mycelium, indicating diffusion of these enzymes.