Comparative Study Of Species Diversity Between Endolichenic Fungi From The Young And Adult Umbilicaria Esculenta Lichens

Lichens are an ecological obligate, stable mutualism between a fungal mycobiont and a greenalgal and/or cyanobacterial photobiont.Lichens,as the pioneer organisms, are widely distributedand can adapt to a variety of extreme environment. Lichens also host numerous endophyticfungal species, in addition to the mycobiont.‘Endolichenic fungi’–fungi living within healthylichen thalli–represent some lineages of Ascomycota that are distinct from mycobionts of lichen,lichenicolous fungi, and incidental fungi on thallus surfaces and show their associations withphototrophic organisms by their symptomless infections, horizontal transmission, high speciesdiversity, and taxonomic similarity. They represent at least five classes of nonlichenizedPezizomycotina, dozens of families, and large numbers of unknown species previously.In this paper,we choose the young and adult Umbilicaria esculenta lichens collected fromDadoudigou, Wangqing County, Jilin Province as experimental materials to isolate and cultureendolichenic fungi.The results show that there are numerous endolichenic fungi inside the thalli,and the young thalli harbor more endolichenic fungi than the adult. This study used a method ofshaving upper cortex layer and collecting hyphae of medulla layer to isolate the endolichenicfungi from the adult and young lichens which each has60speciments,and received286strains. Ichose255strains of filamentous fungi to go on the DNA extractoion, PCR amplification of ITSnrDNA and sequencing and after that, obtioned228ITS sequences of endolichenic fungi. Iemployed the software MAFFT to compare, MEGA5.2to compile,GenBank databases to search,Minimum-Evolution method to construct the phylogenetic tree. After the molecular biologyidentification, these fungal isolates were identified belong to the phylum Ascomycota. Theybelong to4classes: Sordariomycetes, Dothideomycetes, Eurotiomycete and Lecanoromycetes;9orders: Chaetothyriales, Hypocreales, Xylariales, Pleosporales, Myriangiales, Capnodiales,Dothideales, Eurotiales and Peltigerales;14families;19genera and most unknown species.In the experiments,numerous dominant strains:the rock-inhabiting melanized fungi, wereobtained. They include3genera: Capronia, Rhinocladiella, Cladophialophora, and belong toHerpotrichiellaceae, Chaetothyriales, Eurotiomycetes. The results show that those rock-inhabiting melanized fungi may be stable settlers in Umbilicaria lichens and has closerelationship with rock-inhabiting fungi.Based on melocular identification results, we compared the species diversity of endolichenicfungi from the young and adult U.esculenta lichens. I obtained183strains from the younglichens which represent3classes,7orders,11families,11genera and29species(includingunknown) and45from the adult which represent4classes,7orders,9families,10genera and19species(including unknown),and the number of melanized fungi from the young lichens(153) ismuch more than that from the adult(24). From the results, we could see the endolichenic fungi ofthe young lichens are more than those of the adult in number, variety, density, in other words,and the relative biomass. Based on the results, we could conclude that it is a open system beforethe lichen forms. Other microbe also could enter the system except the mycobiont. And after thelichen forms, the system close,so those fungi become endolichenic fungi.During the growth ofthe lichen, it is hard for other fungi to enter inside the thalli. This thesis provide theoretical basisfor research, development and utilization of lichens and endolichenic fungi.