The Community Structure Of Russulaceae Associated With Pure Forest Of Quercus Mongolica And Its Correlation With Ecological Factors

Most species of the Russulaceae are ectomycorrhizal(ECM)fungi,which widely distribute in the world.They form ectomycorrhizal fungi with woody plants and have important ecological functions such as regulating soil carbon and nitrogen cycling in forest ecosystems.At the same time,the vegetation types,physical and chemical properties of soil,climatic factors,and soil microorganisms in forest ecosystems are also important factors influencing the communities formation of Russulaceae fungi.In this study,the pure forest of Quercus mongolica in Wudalianchi City,Heilongjiang Province was taken as the research object.The methods of combining investigating and classifying large-scale fungal resources and the microecology of mycorrhizal fungi with Illumina Hiseq second-generation sequencing,which were used to explore that the dynamic changes of the community structure of Russulaceae with different niche levels from the above-ground and below-ground in Q.mongolica forest,and the key influencing factors during the growth season(June-October)that provide basis for the protection and utilization of Russulaceae fungi resources.The findings are shown below:(1)The five-point sampling method was used to collect the mycorrhiza of Q.mongolica and the ITS sequence of the fungus was sequenced by Illumina Hiseq sequencing.The results showed that there were 40 OTUs were identified to the Russulaceae in mycorrhiza,accounting for 2.78% of the entire fungal community(1440 OTUs),the number of species of Russulaceae was highest in September,lowest in August.And they were clustered into 31 species of Russula,1 species of Lactifluus and 6 species of Lactarius,and Russula was the dominant genus.The number of species of Russula and Lactarius showed a trend of first decrease,increase and then decrease;the number of species of Lactifluus showed a trend of first increase,decrease and then increase.(2)The same method was used to investigate Russulaceae fungi in the root soil of Q.mongolica forest.The results showed that there were 46 OTUs were identified as members of Russulaceae,comprising 3.31% of the entire fungal community(1388 OTUs),the number of species of Russulaceae in the soil was highest in October and lowest in June.And they were clustered into 34 species of Russula,1 species of Lactifluus,and 4 species of Lactarius,and Russula was the dominant genus.During the growing season,the species numbers of Russula and Lactarius in the root soil showed a trend of increase,decrease and increase;the species number of Lactifluus showed no obvious change trend.The community composition of Russulaceae fungi on the below-ground of Q.mongolica forest was significantly affected by the average monthly air temperature,monthly rainfall and average monthly air relative humidity.Moreover,the relative abundance of Russulaceae in the root showed a linear correlation with the relative abundance of the other fungal genera in root and soil.(3)The random investigation method was used to continuously investigate the fruit bodies in the pure forest of Q.mongolica during the growing season from June to October.The morphological and anatomical characteristics combined with ITS sequence information were used to classify.A total of 11 species of Russula,1 species of Lactifluus,and 3 species of Lactarius were detected,which Russula included 6 subgenus and Lactarius included 2 subgenus.The ITS regional phylogenetic analysis of the Russulaceae fungi was shown as follows: Russulaceae formed three branches of Russula,Lactifluus and Lactarius,with a support rate of 100%.Among them,Russula and Lactifluus were closely related and formed a large branch,with a support rate of 94%,Lactifluus species gather alone on a small branch with a support rate of 98%;Lactarius formed a large branch alone,with a support rate of 86%.And Russula were the dominant genus.During the growing season,the number of species of Russulaceae showed a trend of first increase and then decrease,reaching a peak in August,and fruit bodies of Russula appeared earlier than Lactarius and Lactifluus.The Menhinick richness index and Shannon diversity index of Russulaceae species were both the largest in August,followed by July,September,October,and June;the Pielou evenness index was the largest in July,followed by August,September,October,and June.By the correlation analysis between the community composition of Russulaceae and the physico-chemical properties of the habitat soil and climatic factors in pure forest of Q.mongolica,the results revealed that the composition of Russulaceae was significantly affected by the average monthly air temperature,average monthly air relative humidity,monthly rainfall,soil moisture and soil organic matter.(5)By comparing the community composition of Russulaceae fungi between above-ground and below-ground in Q.mongolica forest,the results showed there were a total of 49 species of Russulaceae,including 40 species of Russula,1 species of Lactifluus and 6 species of Lactarius.The results for one-way ANOVA of the Shannon diversity index between above-ground,the root and the soil showed that there were significant differences between the above-ground and the root,and between the above-ground and the soil in July;there was a significant difference between the above-ground and the root,and no significant difference between the above-ground and the soil in August.