Abstract: [Objective]The host trees are damaged by Sirex noctilio and Amylostereum areolatum coordinately. But the endophytic of the host trees also have an impact on the growth of A. areolatum. In China, the invasion of S. noctilio in coniferous mixed forest only results in the injury of Pinus sylvestris var. mongolica. This study was to clarify the differences in species, quantity and distribution of the conifer-inhabiting fungi associated with four kinds of conifers in coniferous mixed forest, and determine the dominant fungus of P. sylvestris var. mongolica invaded by S. noctilio, to reveal the relation between the endophytic diversity and S. noctilio invasion.[Method]We used tissue isolation, morphology and molecular biology methods to study the endophytic fungi of P. sylvestris var. mongolica,Larix gmelinii,Pinus koraiensis,Picea asperata in mixed conifer forest invaded by S. noctilio.[Result]Totally, we had isolated 35 species of endophytic fungi belonging to 22 genera from our experimental material. The endophytic fungi isolated from P. sylvestris var. mongolica,L. gmelinii,P. koraiensis and P. asperata refer to 13 species in 9 genera, 13 species in 7 genera, 17 species in 8 genera and 20 species in 15 genera, respectively. Comparing the results referred to endophytic fungi from the 4 kinds of conifers exhibited a conclusion of total amount:L. gmelinii > P. asperata > P. koraiensis > P. sylvestris var. mongolica; and the diversity of endophytic fungi:P. asperata > L. gmelinii > P. koraiensis > P. sylvestris var. mongolica. As the isolation ratio of sample from different trunk height of healthy pines, the maximum was from the upper part of trunk, whereas the minimum was from the basal part of trunk. The maximum strain species was from the upper part of trunk, and the minimum was from the middle part of trunk. The diversity level of endophytic fungi varies among the four kinds of conifers. The diversity index (H'=3.342 5), evenness index (J=1.097 9) and richness index (R=3.374 4) of P. asperata were the highest among the four species. The similarity of endophytic fungi were low among the four species. Four species of endophytic fungi can be isolated from all the four kinds of conifers, accounting 11.43% of the total species; 20 kinds of fungi were isolated in one kind of conifer, accounting 57.14% of the total species; which illustrates the host-specificity of the conifer-inhabiting fungi.[Conclusion]A certain amount of fungi are present in four kinds of conifers and species vary among this four conifers. Dominant fungi of P. sylvestris var. mongolica invaded by the S. noctilio are different from which of the other kinds of conifers in coniferous mixed forest. Both of the amount and kinds of fungi of P. sylvestris var. mongolica are the least compared to the other species. This may be beneficial for the invasion of A. areolatum and could be the potential causes of S. noctilio injury only happens to P. sylvestris var. mongolica.

Key words: Sirex noctilio, endophytic fungi community, P.sylvestris var.mongolica, Pinus koraiensis, Picea koraiensis, Larix gmelinii, diversity