Capability of the European and North American race of Gremmeniella abietina to hydrolyse polygalacturonic acid in vitro

Abstract

Polygalacturonase was found to be one of the first enzymes secreted by a pathogen during infection. The polygalacturonic-acid hydrolysing activity was compared between the North American and the European race of Gremmeniella abietina in vitro. Isolates were grown in pure pectin media from which the enzyme activity was analysed. Altogether, 29 isolates were tested in hve experiments (experimental runs in a growing chamber). The data were analysed using variance-component models that included fixed-race effects and random-experiment, isolate, flask and measurement effects. The European race secreted more poJygalacturonic-acid hydrolysing enzyme than the North American race and the mycelial dry weight produced was smaller for the European race. The differences between races were of the same order of magnitude as the variation between isolates within races; variance components relating to experimental errors were quite large. No correlation was found between the activity and mycelial dry-matter production within the races. Logarithmic transformation removed the apparent racial differences in the variabihty of the activity and mycelial dry weight. Results from the additionally tested A-and B-type of Fmnish isolates indicated differences in dry-matter production.

Enzymatic interactions between Gremmeniella abietina var. abietina, European race, and two resistant hosts, Pinus banksiana and P. contorta

“…Herron et al 2000). Previous reports (Petäistö and Kajander 1993;Petäistö and Lappi 1996) have proposed that both races (EU and NA) of GAA could potentially secrete at least one enzyme with polygalacturonase activity because G. abietina can grow on a medium with pectin as a sole carbon source. Pectin degradation in the susceptible P. resinosa was also clearly reported using two monoclonal antibodies, JIM-5 and JIM-7, specific to pectin with varying degrees of esterification (Ylimartimo et al 1997).…”

“…This pathogen penetrates its hosts through stomata (Ylimartimo et al 1997) but soon has to deal with various cell walls in order to colonize the host further. In vitro studies revealed that G. abietina is surrounded by an extracellular sheath (ES) containing chitin, galactose, proteins, lipids and polygalacturonic acids (Benhamou and Ouellette 1987a,b) and that it could produce several enzymes such as cellulase, glucanase, xylanase and polygalacturonase (Petäistö et al 1992(Petäistö et al , 1994Petäistö and Kajander 1993;Petäistö and Lappi 1996). Using histo-and cytochemical tests, significant progress has been made in understanding host-pathogen interactions involving G. abietina.…”

Management of Gremmeniella abietina by means of biological control agents and host resistance

“…xylanase and polygalacturonase (Petäistö et al, 1992(Petäistö et al, , 1994Petäistö and Kajander, 1993;Petäistö and Lappi 1996; which seem essential during this process.…”