Abstract
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, Ageratina adenophora, 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 Colletotrichum (34.61%), Diaporthe (17.24%), Allophoma (8.03%), and Fusarium (4.44%). Colletotrichum and Diaporthe were primarily isolated from mature leaves, Allophoma from stems, and Fusarium from roots, indicating that the enrichment of endophytic fungi is tissue-specific and fungi rarely grew systemically within A. adenophora. In the surrounding environment, Alternaria (21.46%), Allophoma (19.31%), Xylaria (18.45%), and Didymella (18.03%) were dominant in the withered leaves, Cladosporium (22.86%), Trichoderma (14.27%), and Epicoccum (9.83%) were dominant in the canopy air, and Trichoderma (27.27%) and Mortierella (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 A. adenophora. 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 A. adenophora was partially shared with the contiguous environment. The data suggested a frequent interaction between fungi associated with A. adenophora and those in surrounding environments, reflecting a compromise driven by both functional requirements for plant growth and local environmental conditions.
Highlights
Biological invasion has seriously threatened ecosystem services and caused huge economic losses (Vilà et al, 2010)
Callaway et al (2004) reported that soil microbes were involved in negative plant–soil feedback in the growth of Centaurea in the plant’s native range but positive feedback outside of this range; Crocker et al (2015) found that the pathogenic fungi Pythium accumulated in invaded soils and caused the death of many native plants while indirectly enhancing the Phragmites australis invasion
We found that the invasive plant A. adenophora enriched the cultivable endophytic fungi, which showed a significant tissue specificity, and demonstrated that the fungi rarely occurred systemic growth
Summary
Biological invasion has seriously threatened ecosystem services and caused huge economic losses (Vilà et al, 2010). Callaway et al (2004) reported that soil microbes were involved in negative plant–soil feedback in the growth of Centaurea in the plant’s native range but positive feedback outside of this range; Crocker et al (2015) found that the pathogenic fungi Pythium accumulated in invaded soils and caused the death of many native plants while indirectly enhancing the Phragmites australis invasion. Previous studies on native plants and crops indicated that fungal endophyte communities varied based on host genotypes (Emi and Kenji, 2013), plant tissues (Wearn et al, 2012), growth stages (Shi et al, 2016), and distribution areas (Geisen et al, 2017). Endophytic fungi have been proven to be a contributor to the competitiveness of exotic plants (Aschehoug et al, 2012), their variation in different tissues has not been investigated in detail during the geographical expansion of invasive plants
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