Hypersensitive Response and Invasion of Stelar Regions of Norway Spruce Germling Roots by Heterobasidion annosum : Root and Butt Rots

Uppsala

International Union of Forest Research Organizations, Swedish University of Agricultural Sciences

1994

S. 88-103

19 Lit. Ang.

Bandaufführung

13462

73440

Induction of hypersensitive response and colonisation of cortical tissues was found to be a function of both spore concentration and time. Increase in browning of root tissues was found within 72 hr post infection (p.i.) using 10hoch6 - 10hoch7 spores/ml. Some saprophytic and pathogenic fungi were assessed for their ability to induce similar hypersensitive response. Elisa studies showed that a polyclonal antibody raised against Heterobasidion annosum cross reacted with hyphal extracts of all the fungi tested. Slight induction of hypersensitive response was observed with concentrated culture filtrates of Heterobasidion annosum or dialysed ammounium sulphate precipitate of the filtrate. Similarly, NaCl, ethephone and polygalacturonic acid (PGA) induced significantly stronger response than pectin and chitin. Invasion of cortical regions was observed within 72hr using high inoculum concentration but was delayed to 12-15d with a low spore concentration (10hoch2 - 10hoch3 spores/m.). Penetration of stelar regions occurred 10 - 15 d p.i. Invasion of cortical and endodermal regions was correlated with increased lignification, phenolic accumulation and papillae formation.