Root-Associated Bacteria Community Characteristics of Antarctic Plants: Deschampsia antarctica and Colobanthus quitensis—a Comparison

Abstract

Colobanthus quitensis (Kunth) Bartl. and Deschampsia antarctica Desv. are the only Magnoliophyta to naturally colonize the Antarctic region. The reason for their sole presence in Antarctica is still debated as there is no definitive consensus on how only two unrelated flowering plants managed to establish breeding populations in this part of the world. In this study, we have explored and compared the rhizosphere and root-endosphere dwelling microbial community of C. quitensis and D. antarctica specimens sampled in maritime Antarctica from sites displaying contrasting edaphic characteristics. Bacterial phylogenetic diversity (high-throughput 16S rRNA gene fragment targeted sequencing) and microbial metabolic activity (Biolog EcoPlates) with a geochemical soil background were assessed. Gathered data showed that the microbiome of C. quitensis root system was mostly site-dependent, displaying different characteristics in each of the examined locations. This plant tolerated an active bacterial community only in severe conditions (salt stress and nutrient deprivation), while in other more favorable circumstances, it restricted microbial activity, with a possibility of microbivory-based nutrient acquisition. The microbial communities of D. antarctica showed a high degree of similarity between samples within a particular rhizocompartment. The grass’ endosphere was significantly enriched in plant beneficial taxa of the family Rhizobiaceae, which displayed obligatory endophyte characteristics, suggesting that at least part of this community is transmitted vertically. Ultimately, the ecological success of C. quitensis and D. antarctica in Antarctica might be largely attributed to their associations and management of root-associated microbiota.

Simulated global warming affects endophytic bacterial and fungal communities of Antarctic pearlwort leaves and some bacterial isolates support plant growth at low temperatures

“…and Yersiniaceae ( Rahnella sp.). These findings agree with previous studies that demonstrated the colonization of C. quitensis endosphere and rhizosphere mainly by Actinobacteria, Bacteroidetes, Firmicutes, and Proteobacteria 16 , 23 . In particular, Microbacteriaceae , Pseudomonadaceae, and Sphigomonadaceae families are known to dominate C. quitensis endosphere and phyllosphere 17 , suggesting possible adaptation of endemic bacterial taxa to Antarctic conditions.…”

“…For example, bacterial communities of C. quitensis rhizosphere can be influenced by neighboring plants (e.g., D. antarctica ) and bird presence at the collection site 16 . Moreover, the relative abundances of Micrococcaceae and Xanthomonadaceae families of C. quitensis rhizosphere and endosphere can be affected by the geochemical soil background of the collection sites in Antarctic environments 23 .…”

“…Colobanthus quitensis -associated communities have been partially investigated, demonstrating that Actinobacteria, Bacteroidetes, Firmicutes, and Proteobacteria are the most abundant (dominant) bacterial phyla 14 – 17 , while Ascomycota and Basidiomycota are the dominant fungal phyla 5 , 18 – 20 . However, C. quitensis -associated microorganisms were mostly explored using culture-dependent approaches 5 , 14 , 15 , 18 – 23 and the effect of plant growth conditions on the taxonomic structure of endophytic bacterial and fungal communities of C. quitensis is almost unknown. Moreover, the functional properties of C. quitensis -associated microorganisms were mainly reported for endophytic fungi 12 , 24 – 29 , while less information is available for endophytic bacteria.…”

Source and acquisition of rhizosphere microbes in Antarctic vascular plants

“…Then, the use of 16S rRNA showed that bacteria found in the rhizosphere of Da and Cq were very different from those reported in adjacent bulk soil ( Teixeira et al, 2010 , 2013 ). Additionally, no differences were found between the bacterial communities of Da and Cq, and both rhizospheres were composed of Firmicutes, Actinobacteria, and Proteobacteria ( Teixeira et al, 2010 , 2013 ; Jorquera et al, 2016 ; Rabert et al, 2020 ; Znój et al, 2021 ). One of the most recent studies used shotgun sequencing to demonstrate that Da and Cq rhizospheres were composed mainly of Proteobacteria, Actinobacteria, and Bacteroidetes, finding differences between the rhizosphere bacteria of both plants only at the genus level ( Molina-Montenegro et al, 2019 ).…”

Meta-analysis of root-associated microbial communities of widely distributed native and invasive Poaceae plants in Antarctic.

“…Rhizospheric bacteria can also secrete organic acids, siderophores, or cyanide to participate in the dissolution of mineral matrices, thereby indirectly affecting plants. Endophytes have a major contribution to promoting plant growth by providing fixed nitrogen (Znój et al, 2021a;Oses-Pedraza et al, 2020).…”