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ABSTRACT
Background
Invasive plants may displace native species. This is the case for Poa annua, the only non-native plant species successfully established in Maritime Antarctica. Nonetheless, it is uncertain which factors drive the competitive success of P. annua in the harsh environmental conditions of the region. The ability of this plant species to establish novel mutualistic interactions with resident soil fungi may be crucial for its invasiveness. Such ability may be linked to the vertical transmission of fungal endophytes via seeds.
Aims
We undertook a study to assess the role of seed fungal endophytes as promoters of the establishment and invasion of Poa annua in Maritime Antarctica.
Methods
We explored the composition and diversity of fungal communities associated with different P. annua tissues (seeds, leaves and roots) and the soil. We also measured parameters including germination rate, above-ground biomass, reproductive structures, and the survival of invasive P. annua as well as of the native Colobanthus quitensis and Deschampsia antarctica grown from seeds with and without endophytes. Furthermore, we conducted inter- and intraspecific competition experiments among native and invasive plants, where chemically mediated plant-to-plant interference (allelopathy) and plant growth rate were measured to calculate a relative competition index.
Results
We found that fungal endophyte taxa associated with P. annua tissues were very different from those in the soil. Fungal endophytes in P. annua differed among seed, root and shoot tissues, which suggests low transmission among different organs. The removal of endophytes from P. annua seeds was associated with reduced seed germination, plant growth and survivorship, while the competitive ability of P. annua (assessed by accumulated biomass) relative to native species, as well as levels of allelochemicals in soils, were higher in the presence of seed fungal endophytes.
Conclusion
Our results suggest that fungal endophytes, maternally inherited through seeds, improve host fitness and may contribute to the invasive success of P. annua in Antarctica.
Acknowledgements
We are grateful to the Instituto Antártico Chileno (INACH) for their logistic management during the Expedición Chilena Antartica n°56 (growing season 2019–2020), and to the Henryk Arctowski Polish Antarctic Station crew for their field support and assistance within their facilities.
Author contributions
GB, ISAR and MAMM conceived the ideas; GB, AB and MAMM compiled data; GB and ISAR generated figures; GB, KKN and MAMM wrote the draft manuscript, and all authors contributed to editing it.
Disclosure statement
No potential conflict of interest was reported by the author(s).
Data availability
All sequence data were submitted to NCBI Sequence Read Archive (SRA) and are available under the Bioproject accession number PRJNA812056. Representative ASVs sequences, fungal taxonomic assignments, diversity analysis tables including FUNGuild results, and supplementary files have been deposited into Figshare (doi.org/10.6084/m9.figshare.c.5889431).
Supplementary material
Supplemental data for this article can be accessed online at https://doi.org/10.1080/17550874.2022.2145579
Additional information
Funding
Notes on contributors
Gabriel I. Ballesteros
Gabriel I. Ballesteros is a research associate; his main research line is related with molecular and bioinformatic tools applied to ecological issues.
Ian S. Acuña-Rodríguez
Ian S. Acuña-Rodríguez is a research associate; his main research line is related with data analyses applied to biological issues.
Andrea Barrera
Andrea Barrera is a Ph.D. student with expertise in environmental microbiology and molecular tools.
Pedro E. Gundel
Pedro E. Gundel is an Associate Professor. His main research line is devoted to symbiosis between fungal endophytes and grasses, with ecological, evolutive and chemical approaches.
Kevin K. Newsham
Kevin K. Newsham’s main research include polar microbiology and symbiosis among fungal endophytes and polar vegetation.
Marco A. Molina-Montenegro
Marco A. Molina-Montenegro is Professor of ecology. His main research line is the functional symbiosis among plants and microorganisms from extreme environments.