Intraspecific variation in Heterobasidion annosum for growth in sapwood of Picea abies and Pinus sylvestris.

摘要

Two greenhouse experiments were conducted to study intraspecific variation in growth of H. annosum in living host sapwood. In experiment 1, P. sylvestris and P. abies seedlings were inoculated with H. annosum isolates, 14 each of the S- and P-intersterility groups, collected from various parts of Sweden. In Pinus, the P-group isolates were more virulent than the S-group isolates both in terms of infection frequency, induced mortality rate (p < 0.05), and fungal growth in sapwood (p < 0.05). In Picea, the P-group isolates were also more virulent on average, but the difference was not statistically significant. Both S and P isolates had a higher infection frequency and a significantly longer sapwood growth on Picea than on Pinus. The P-group causedhigher mortality on Pinus than on Picea. The length of the lesion in the inner bark was strongly correlated with fungal growth in spruce, but not in Pinus where the lesions were short or absent. In experiment 2, ten Norway Picea clones were inoculated with 18 S-isolates, originating from nine live-decayed trees and from nine spore-infected stumps in a single P. abies stand. The objective was to test whether any selection for growth rate in sapwood was detectable among individuals of H. annosum originating either from stumps or trees. The results gave no support for such selection since no difference in sapwood growth between the two groups of isolates was found.