Mycoflora Biodiversity And Genetic Variation Of Macrofungi In Alpine Meadow Of Tibet

The Qinghai-Tibet Plateau(QTP)is the highest plateau in the world,and entiled the name as the roof of the world and the third pole.The QTP mountains reached their current height mainly between the late Miocene and late Pliocene.The uplift of altitude leads to the formation of its unique environmental conditions and diverse species resources in the Qinghai-Tibet Plateau.However,the investigation of fungal species resources in this area is severely hampered due to its harsh environment and poor transportation.Our research group has been focusing on the investigation of macrofungi in Tibet since 2015.In the course of this endeavor,we found that the vegetation in this area is mainly comprised of alpine shrubs,alpine meadows,mosses and lichens,especially in the areas of over 4000 meters above sea level,and most of them are species with obvious Alpine desert characteristics.Most of the vegitations are densely growing,have small morphos and full adaptation to the environments.In parallel,the macrofungi in the same biotope also showed similar characteristics.The elevation has direct impact on the vertical distribution of fungi species.The natural environment in over 4000 meters above sea level is extremely hostile: the average annual temperature is less than 0? with large day/night fluctulations,and strong UV radiation,especially in the area over 4000 meters above the tree distribution line.It is suggested that the macrofungi may have evolved a series of adaptive changes by the strong natural selections.Our long-term goal is to explore the diversity of macrofungi in this area and unravel the genetic basis by which macrofungi has successfully adapted to the complex and extreme conditions on the QTP.This study was based on two field investigations to QIP: from July to September in 2016 and 2017,respectively.We have focused on the alpine tundra,especially over 4000 meters on Shergyla Mountain?Gawalong Mountain and Mila Mountain.In total,283 specimens were collected,according to identification,they belong to 2 phyla,3 classes,13 orders,37 families,71 genera and 183 species.We also analyzed the floristic characteristics and species composition of fungi in this area.There are 5 dominant families(?10 species in each),and 11 dominant genera(?5 species in each),and most of the macrofungi in this area belong to species with characteristics of north temperate distribution and similarity coefficients showed that the floristic diversity of Macrofungi in Tibetan alpine meadow has the highest similarity with Yunnan Province.The results of soil amplicon sequencing in this region illustrate the potential diversity of fungi in this region,however,compared with Macrofungi,the abundance of soil fungi is higher and the community richness and community diversity were all negatively correlated with altitude,that is,with the increase of altitude,the community richness and community diversity were all decreased.Genome-wide analysis showed that the genome sizes of macrofungi at different altitudes differ substantially,with genomes of high-altitude species being generally larger than those of their low-altitude relatives.Moreover,the repetitive sequences,especially the long terminal repeat(LTR)retrotransposons are positively correlated with the altitude and the Ngaro family of LTR has the greatest change.Compared with low-altitude fungi,high-altitude fungi have a large number of genomic structural variations,with rampant gene insertions and deletions.Compared with the low-altitude species,the expanded gene families and positively selected gene families of the high-altitude species are significantly enriched in pathways related to DNA damage repair,maintenance of cell membrane stability,signal transduction,enzyme activity and reproduction;the contracted gene families are significantly enriched in pathways involved in disease and immune response.The common extended gene families of different species at high-altitude is mainly involved in low temperature response and hypoxia metabolic pathway.In conclusion,this study has enabled the collection of valuable specimens and provided fundmental information of macrofungi resources in the alpine tundra of Tibet.The comparative genome analyses of macrofungi at different altitudes revealed the possible adaptive genomic and genetic changes of macrofungi at high altitudes,which are most probably due to strong selction natural and adaptive evolution.