Diversity And Distribution Pattern Studies On Lignicolous Freshwater Fungi In Lancang River

Lignicolous freshwater fungi was a fungus growing on submerged decaying wood,whose whole life cycle or part of life cycle depended on water environment.Lignicolous freshwater fungi are important microbial components in freshwater ecosystems and play an important role in freshwater ecosystems.They can decompose plant residues,cellulose and organic matters with high lignin content in water bodies and are eaten by aquatic animals into the food chain.Blackwell,based on metagenomics,estimates that there are about 1.5 to 5.1 million species of fungi on earth,and there are now an estimated 2.2 to 3.8 million fungal species.Shearer & Raja(2018)counted about 135,000 species of fungi reported,of which about 65,000 species were ascomycetes,most of which were from terrestrial habitats,while few were reported from aquatic ascomycetes.Yunnan is one of the most biodiverse provinces in China,but there are few studies on Lignicolous freshwater fungi,especially on the lancang river basin.This project is divided into three sections to study the lignicolous freshwater fungi on the samples of saprophyllum lancang river,identify the species by combining morphological and molecular systematics methods,and systematically study the diversity composition of lignicolous freshwater fungi and its relationship with altitude,water area,temperature,climate and environment.The results are as follows:1.A total of 2070 samples of submerged decaying wood from lancang river were collected,and 866 strains were obtained.According to morphological characteristics and phylogenetic development,320 species of 180 genera were identified,among which 59 species of 47 genera were identified in the upstream of lancang river,124 species of 74 genera were identified in the middle reaches,and 192 species of 135 genera were identified in the downstream.the Shannon's diversity index H' of freshwater woody fungi in the upper,middle and lower reaches of lancang river were 3.18,3.81 and 4.36 respectively.S?rensen's index of similarity of the upper,middle and lower reaches of the lancang river were: middle and lower reaches(0.089),upper and middle reaches of >(0.058),and upper and lower reaches of >(0.054).The results showed that the species diversity of the lower reaches of lancang river was the highest,the middle reaches was the second,and the upper reaches was the lowest.The community similarity between the middle reaches and the lower reaches was the highest,and the community similarity between the upper reaches and the lower reaches was the lowest,indicating that the geographical distance would affect the community composition of freshwater fungi.2.In this study,we conducted statistical analysis on species diversity of lignicolous freshwater fungi at different elevations in the lancang river basin.Species richness and detection rate tend to increase first and then decrease with elevation(500–1000m),(1000–2000m),(2000–3000m),(3000–4000m)and(4000–4500m).the Shannon's diversity index H' analysis shows that the diversity of freshwater woody fungi reaches its peak in the middle and high altitude,which is consistent with the conclusion of Shearer et al.The distribution pattern of Lignicolous freshwater fungi along the altitude has species specificity.Some groups only appear in the high altitude segment,such as Artocarpomyces,Ascolacicola,Cirrenalia,etc.Some groups are only distributed in the low altitude segment,such as Dictyochaeta,Digitodesmium,Endophragamiella,etc.,while some groups are distributed in each altitude segment,such as Aniptodera,Astrosphaeriella,Dactylaria,etc.3.Relationship between temperature and diversity of freshwater woody fungiIn this study,we measured the water temperature of sample points in the lancang river basin to evaluate the influence of water temperature on the species abundance of Lignicolous freshwater fungi.Acquisition of the cryogenic temperature 2.4 ?,the most high temperature 29 ?,species diversity along with the rise of temperature is on the rise.4.The diversity of lignicolous freshwater fungi in various climatic regions of lancang river basin(Temperate zone,subtropical zone and tropical zone)was studied,and the results showed that the species diversity of freshwater woody fungi was the highest in tropical zone and subtropical zone,which was consistent with the findings of Hyde et al.5.The latest phylogenetic tree of Dictyosporaceae was established,a new genus,Aquadictyospora,and a new species within the genus,Aquadictyospora lignicola,was introduced,and a new Chinese record species,Pseudodictyosporium wauense,was reported,and the corresponding morphology was described,providing molecular phylogenetic evidence.6.In this paper,the endemic species,dominant species,24 common hyphomycetes and 8 ascomycetes of fresh water woody fungi in different sections of lancang river were described in detail,and the corresponding map plates were attached.