Study On Diversity Of Cohabitant Fungus And Cohabitant Mechanism With Tremella Fuciformis Based On Genome Sequence

Tremella fuciformis Berk.is a well-known edible and medicinal fungus in China.However,it is also a very special fungus.On sawdust or other substrates,the growth and reproduction of T.fuciformis are only possible with the presence of another fungus,commonly called "Xianghuijun".T.fuciformis has not the ability to complete life cycle alone in the substrate with lignocellulose.It is necessary for the xianghuijun as a trailbreaker.However,not all the xianghuijuns known can help T.fuciformis fruit.The mechanism of the interaction between T.fuciformis and different xianghuijuns has not kown yet.These will cause some obstacles to the genetic breeding of T.fuciformis and xianghuijun.In this study,we made comparisons about colonial morphology and antagonism and growth rate among six xianghuijuns we selected.At the same time,we completed the ITS sequencing and fruiting experiment and genetic polymorphism analysis of the fungus.As a result,those fungus were divided into two categories,one is the xianghuijun that can help the T.fuciformis fruit,including G03,Hp.sp0004,Hp.sp0006,Hp.sp0026,the length of ITS sequence is about 900 bp,of which the sequence similarity is reaching up to 99%.Besides,those have 99%similarity with Annulohypoxylon stygium and Hypoxylon sp.in NCBI.The others are the xianghuijuns that can not help the T.fuciformis fruit,including Hp.sp0029 and Hp.sp0032,which have an ITS sequence about 1,000 bp,those have 98%similarity with Annulohypoxylon stygium and Fungal endophyte sp.in NCBI.Then,according to the results of classification,we selected the G03,Hp.sp0029 and Hp.sp0032 for further research.Firstly,we found that there were some differences between G03 and Hp.sp0032 in microscopic structure.Based on the fruit out of the substrate,we concluded that the mycelia of T.fuciformis could suck the nutriment from xianghuijun.Hence,if the mycelia of T.fuciformis were inoculated on the mycelia of xianghuijun such as G03 but not the Hp.sp0029 or Hp.sp0032,the T.fuciformis can fruit only suck the nutriment from xianghuijun.Besides,in the hypha of T.fuciformis,there was a subglobose basal part with one or more thread-like filaments.Unexpectedly,those subglobose basal parts not only become attached to the G03 but also the Hp.sp0032.Afterwards,based on the next-generation sequencing of Illunina,we re-sequenced the xianghuijun Hp.sp0029 and Hp.sp0032,and assembled them.The result of assembling showed that the total length of the assembled genome of Hp.sp0029 are about 38 Mb,including 47.71%GC and 944 scaffolds in which N50 was 73,467 bp.At the same time,we gained about 38 Mb assembled genome of Hp.sp0032,including about 47.04%GC and 981 scaffolds in which N50 was 65,876 bp.With the prediction of software Augustus（version2.5.5）specially used for fungus,we gained 9,359 genes from the whole genome of Hp.sp0029 and 9,030 genes from Hp.sp0032.Then we annotated their functions of these genes using GO,COG and KEGG et al.Then,when we changed the research strategy,which was based on the software of salamand,homologous comparison was made among xianghuijun G03,Hp.sp0029 and Hp.sp0032.As a result,we found 679 genes special for G03,which may play an important role in helping T.fuciformis fruit.And then we annotated the function of these genes using GO、COG and KEGG.Besides,we continued to carry out the homologous comparison among xianghuijun G03、Hp.sp0029 and T.fuciformis.As a resut,we found 832 genes special for G03,and 862 genes special for Hp.sp0032.And also we annotated the function of these genes using GO、COG and KEGG,and compared their functional differences.In order to explore the difference of CAZymes among xianghuijun G03,Hp.sp0029,Hp.sp0032,T.fuciformis,we selected the different carbon sources including D-glucose,D-xylose,soluble starch,beechwood xylan,cellulose and lignin solely to cultivate the xianghuijun G03,Hp.sp0029,Hp.sp0032 and T.fuciformis,at the same time,we chose the PDA and no carbon source as a contrast.As a result,it showed that the T.fuciformis only could utilize the monosaccharide such as D-glucose and D-xylose,could not grow in substrate with a carbon source of polysaccharide.On the contrary,the xianghuijun had powerful ability to utilize the polysaccharide,but Hp.sp0029 was weaker than G03 or Hp.sp0032.The result of Carbohydrate-Active Enzyme database annotation from T.fuciformis and xianghuijun G03,Hp.sp0029,Hp.sp0032 showed that the T.fuciformis had a relatively small number of GH-encoding genes,and lacked some GHs and without PLs and AA9 that relate to cell wall degradation.Besides,T.fuciformis lacked the exonuclease（AA9,GH7）,but the number of GT48（Sugar_tr/MFS₁）was much more than the xianghuijun.The number and variety of CAZymes among G03,Hp.sp0029 and Hp.sp0032 were not very different,however,with the xianghuijun Hp.sp0029 or Hp.sp0032,the T.fuciformis still could not fruit on the cultivation substrate.Many discrepansies in AD binding domain,Cytochrome P450,NAD_binding₈,Major Facilitator Superfamily transporter/Sugar（and other）transporter,Biological adhesion existed among two kinds of xianghui species,as a result,it may be led to that the xianghui of Hp.sp0029 and Hp.sp0032 could not transport the effective nutrient to the T.fuciformis successfully.Hence,we concluded that except for the ability of substrate degradation,Smooth transport tunnel between T.fuciformis and cohabitant fungus was also needed.Here,we confirmed the relationship of trophism between T.fuciformis and xianghuijun,found some special structures for T.fuciformis to suck nutrient,and reported two genomes of xianghuijun with TIS sequence 1,000 bp.Besides,we compared genome and gene subsets（cellulose,hemicellulose and pectin degradation）with the T.fuciformis and two kinds of xianghuijun（G03、Hp.sp0029 and Hp.sp0032）through combining the genome of xianghuijun G03 and T.fuciformis T14 finished in 2012.We gained some insights into the difference of genome and CAZymes families among two kinds of xianghuijun and T.fuciformis.