Priliminary Study On Mycelial Interaction Between Tremella Fuciformis And Hypoxylon Sp.

Mycelial interaction between Tremella fuciformis and Hypoxylon sp.was studied in three aspects:（1） Morphology of the two kinds ofmycelia and the special structures were observed by light microscopy and scanning electronic microscopy.The two fungi and seven different fungi were paired with each other to reveal the morphological distinctions between these interactions.（2） The activities of cellulases（endo-1,4-β-glucanase,exo-1, 4-β-glucanase and 1,4-β-glucosidase）,xylanase,polyphenoloxidase,laccase,chitinase and 1,3-β-glucanase from the pure and mixed cultured mycelia were determined in PDB or wood-chips media.Besides,effects of melanin isolated from Hypoxylon sp.on polyphenoloxidase activity of Trernella fuciformis were studied.（3） Differential expressed genes of Tremella fuciformis in pure culture and co-culture with Hypoxylon sp. were analyzed by RAP-PCR methods.The main results were shown as follows:1.Observation by light microscopy and scanning electronic microscopy showed that mycelia of Tremella fuciformis were always coiling,swollen at terminal and with clear clamp connections,whereas mycelia of Hypoxylon sp.described as a sparse,spindly and straight hapha without clamp connections.Haustoria cells which were obviously observed in mycelia of Tremella fuciformis always attach with many mycelia similar to Hypoxylon sp.in co-culture.Tremella fuciformis had disadvantages in competition with other seven fungi,whereas Hypoxylon sp.showed much strong ability by secreting melanin.The phenomenon of "excreting-yellow-water" and "white-hairball" appeared in colony of Tremella fuciformis when co-cultured with Hypoxylon sp..2.The growing of Tremella fuciformis was not appeared in wood-chips culture media.Meanwhile,the activities of three cellulases in Tremella fuciformis were lower than those in Hypoxylon sp..The maximum of exo-1,4-β-glucanase in co-cultured mycelia were 122.5U in PDB and 502.1U in wood-chips media,which were higher than that in pure culture conditions.It showed that the co-cultured mycelia had stronger cellulose degradation ability.The activity of xylannase in Tremella fuciformis,Hypoxylon sp.and co-cultured mycelia was respectively higher than that of cellulases.The maximum activity of xylanase from co-cultured mycelia in wood-chips media was 923.9U,which was higher than that of 836.1U in Hypoxylon sp.obviously.Hypoxylon sp. showed activity of polyphenoloxidase but no laccase activity.The maximum activity of laccase in Tremella fuciformis was 18.5U,however only 21.5U in co-culture mycelia in PDB.Determination of polyphenoloxidase and laccase activity in pure and mixed culture of Tremella fuciformis and Hypoxylon sp.indicated that they had weak ability in lignin degradation.The activity of chitinase in co-culture mycelia was a little higher than that of Tremella fuciformis,and Hypoxylon sp.in pure culture showed least activity of chitinase in PDB culture.But the activity of 1,3-β-glucanase in these mycelia did not show great difference.Determination of chitinase and 1,3-β-glucanase indicated that Tremella fuciformis had no great ability in fungi cell wall degradation.The maximal activity of polyphenoloxidase in Tremella fuciformis culture in PDB containing 0.05g/L melanin was 156.3U at the 15^th day,which was obvious higher than that of control and culture in PDB containing other concentrations of melanin.3.Total RNA were extracted and purified from Tremella fuciformis culture in two different conditions,and then quantified to 1μg/mL.Using six primers in RAP-PCR, twelve differential bands were obtained.Altogether nine bands showed efficient amplification after these differential bands were re-amplified with the corresponding primers and the same cycling parameters.PCR products from the nine bands were cloned and sequenced.BLAST analysis of the differential expressed clones in GenBank. Confirmed by Northern hybridization,sequence Seq1 identified as a differential expressed gene.Seq1 showed high similarity to a conserved hypothetical protein in Cryptococcus neoformans var.neoformans.