Tissue-Specific and Geographical Variation in Endophytic Fungi of and Fungal Associations With the Environment.

To understand the distribution of the cultivable fungal community in plant tissues and the associations of these fungi with their surrounding environments during the geographical expansion of an invasive plant, , we isolated the cultivable fungi from 72 plant tissues, 12 soils, and 12 air samples collected from six areas in Yunnan Province, China. A total of 4066 isolates were investigated, including 1641 endophytic fungi, 233 withered leaf fungi, 1255 fungi from air, and 937 fungi from soil. These fungi were divided into 458 and 201 operational taxonomic units (OTUs) with unique and 97% ITS gene sequence identity, respectively. Phylogenetic analysis showed that the fungi belonged to four phyla, including Ascomycota (94.20%), Basidiomycota (2.71%), Mortierellomycota (3.03%), and Mucoromycota (0.07%). The dominant genera of cultivable endophytic fungi were (34.61%), (17.24%), (8.03%), and (4.44%). and were primarily isolated from mature leaves, from stems, and from roots, indicating that the enrichment of endophytic fungi is tissue-specific and fungi rarely grew systemically within . In the surrounding environment, (21.46%), (19.31%), (18.45%), and (18.03%) were dominant in the withered leaves, (22.86%), (14.27%), and (9.83%) were dominant in the canopy air, and (27.27%) and (20.46%) were dominant in the rhizosphere soils. Further analysis revealed that the cultivable endophytic fungi changed across geographic areas and showed a certain degree of variation in different tissues of . The cultivable fungi in mature and withered leaves fluctuated more than those in roots and stems. We also found that some cultivable endophytic fungi might undergo tissue-to-tissue migration and that the stem could be a transport tissue by which airborne fungi infect roots. Finally, we provided evidence that the fungal community within was partially shared with the contiguous environment. The data suggested a frequent interaction between fungi associated with and those in surrounding environments, reflecting a compromise driven by both functional requirements for plant growth and local environmental conditions.