TY - JOUR

T1 - The “Trojan horse” strategy

T2 - Seed fungal endophyte symbiosis helps to explain the invasion success of the grass, Poa annua, in Maritime Antarctica

AU - Molina-Montenegro, Marco A.

AU - Ballesteros, Gabriel I.

AU - Acuña-Rodríguez, Ian S.

AU - Pertierra, Luis R.

AU - Greve, Michelle

AU - Richardson, David M.

AU - Convey, Peter

AU - Biersma, Elisabeth M.

AU - Goodall-Copestake, William P.

AU - Newsham, Kevin K.

N1 - Publisher Copyright: © 2023 The Authors. Diversity and Distributions published by John Wiley & Sons Ltd.

PY - 2023

Y1 - 2023

N2 - Aim: Poa annua L. (annual bluegrass) is presently the sole invasive vascular plant species to have successfully established in Maritime Antarctica, where it poses a significant conservation threat to native plant species. However, the reasons for its success in the region have yet to be established. Here, we determined whether the invasiveness of P. annua, and its competitiveness with the native Antarctic hairgrass Deschampsia antarctica, is influenced by symbioses formed with seed fungal endophytes, and whether plants derived from seeds from four global regions differ in their performance. Locations: Four regions (Maritime Antarctica, sub-Antarctica, South America and Europe). Methods: Endophyte frequency was measured in P. annua seeds collected from the four regions. The germination, survival, biomass accumulation, flowering and competitiveness with D. antarctica of P. annua plants grown from endophyte-uncolonised and uncolonised seeds was determined in the laboratory. The effects of endophytes on P. annua seed germination and survival and seedling osmoprotection were also assessed in the Maritime Antarctic natural environment using locally-sourced seeds. Results: Endophytes were at least twice as frequent in seeds from Maritime Antarctica than in those from other regions. A higher proportion of endophyte-colonized seeds germinated and survived than did uncolonised seeds, but only when they originated from Maritime Antarctica. Seed endophytes increased the competitiveness of P. annua with D. antarctica, but only for plants grown from Maritime Antarctic seeds. In the field, endophyte-colonized seeds from Maritime Antarctica germinated and survived more frequently than uncolonised seeds, and osmoprotection was higher in seedlings grown from colonized seed. Main Conclusions: The findings indicate beneficial effects of seed endophytes on invasion-related traits of P. annua, such as survival, germination success and flowering. Together with vegetative and reproductive traits facilitating the colonization process, the seed-fungal endophyte symbiosis can be invoked as an important factor explaining the invasiveness of P. annua in Maritime Antarctica.

AB - Aim: Poa annua L. (annual bluegrass) is presently the sole invasive vascular plant species to have successfully established in Maritime Antarctica, where it poses a significant conservation threat to native plant species. However, the reasons for its success in the region have yet to be established. Here, we determined whether the invasiveness of P. annua, and its competitiveness with the native Antarctic hairgrass Deschampsia antarctica, is influenced by symbioses formed with seed fungal endophytes, and whether plants derived from seeds from four global regions differ in their performance. Locations: Four regions (Maritime Antarctica, sub-Antarctica, South America and Europe). Methods: Endophyte frequency was measured in P. annua seeds collected from the four regions. The germination, survival, biomass accumulation, flowering and competitiveness with D. antarctica of P. annua plants grown from endophyte-uncolonised and uncolonised seeds was determined in the laboratory. The effects of endophytes on P. annua seed germination and survival and seedling osmoprotection were also assessed in the Maritime Antarctic natural environment using locally-sourced seeds. Results: Endophytes were at least twice as frequent in seeds from Maritime Antarctica than in those from other regions. A higher proportion of endophyte-colonized seeds germinated and survived than did uncolonised seeds, but only when they originated from Maritime Antarctica. Seed endophytes increased the competitiveness of P. annua with D. antarctica, but only for plants grown from Maritime Antarctic seeds. In the field, endophyte-colonized seeds from Maritime Antarctica germinated and survived more frequently than uncolonised seeds, and osmoprotection was higher in seedlings grown from colonized seed. Main Conclusions: The findings indicate beneficial effects of seed endophytes on invasion-related traits of P. annua, such as survival, germination success and flowering. Together with vegetative and reproductive traits facilitating the colonization process, the seed-fungal endophyte symbiosis can be invoked as an important factor explaining the invasiveness of P. annua in Maritime Antarctica.

KW - annual bluegrass (Poa annua)

KW - Antarctic hairgrass (Deschampsia antarctica)

KW - biological invasion

KW - Cladosporium

KW - King George Island

KW - Maritime Antarctica

KW - seed fungal endophytes

KW - symbiosis

U2 - 10.1111/ddi.13768

DO - 10.1111/ddi.13768

M3 - Journal article

AN - SCOPUS:85173115812

VL - 29

SP - 1432

EP - 1444

JO - Diversity and Distributions

JF - Diversity and Distributions

SN - 1366-9516

IS - 11

ER -