VARIABILITY OF POPULATIONS OF THE ECTOMYCORRHIZAL FUNGUS EROCOMUS PRUINATUS INFECTING EUROPEAN BEECH (FAGUS SYLVATICA), SESSILE OAK (QUERCVS PETRAEA) OR NORWAY SPRUCE (PICEA ABIES)

摘要

Allelic frequencies of nine enzyme gene loci were studied in populations of the ectomycorrhizal fungus Xerocomus pruinatus (Fr.) Quel. infecting European beech (Fagus sylvatica L.), sessile oak (Quercus petraea (Matt.) Liebl.)) or Norway spruce (Piceaabies (L.) Karst.). The average number of alleles per polymorphic locus was 2.41. In X. pruinatus populations from European beech 21 to 23 alleles were observed at the nine loci studied, while 20 alleles were found in a population from sessile oak and 16 alleles occured in a population from Norway spruce. The effective numbers of alleles were ne = 1.58, 1.72 and 1.80 for the beech, oak and spruce populations, increasing respectively. Also the mean heterozygosities increased from the populations from European beech (H_E = 0.3332) to the one from sessile oak (H_E = 0.4659) to the one from Norway spruce (H_E = 0.5622). Genetic distances were smallest between fungal populations infecting the same host species (beech: d_0 = 0.091), whereas genetic distances were larger for populations infecting different tree species (oak/spruce: d_0 = 0.1717, beech/spruce: d_0) = 0.2219, beech/oak: d_0 = 0.2595). In individuals on European beech two loci coded for the enzyme system diaphorase, whereas one diaphorase locus was active in mycorrhizae on sessile oak and no diaphorase activity was observed in individuals infecting Norway spruce roots. The host-dependent diaphorase expressions in X. pruinatus are dircussed as adaptations of this ectomycorrhizal fungus to itshost's metabolism.