Microbiome and related structural features of Earth’s most archaic plant indicate early plant symbiosis attributes

Abstract

Origin of earliest land plants from ancestral algae dramatically accelerated the evolution of Earth’s terrestrial ecosystems, in which microbial symbioses have played key roles. Recent molecular diversification analyses identify the rare, geographically-limited moss Takakia as Earth’s most archaic modern land plant. Despite occupying a phylogenetic position pivotal for understanding earliest plants, Takakia microbial associations are poorly known. Here, we describe symbiosis-related structural features and contig-based metagenomic data that illuminate the evolutionary transition from streptophyte algae to early embryophytes. We observed that T. lepidozioides shares with streptophyte algae secretion of microbe-harboring mucilage and bacterial taxa such as Rhizobium and genes indicating nitrogen fixation. We find that Takakia root-analogs produce lateral mucilage organs that are more complex than generally understood, having structural analogies to angiosperm lateral roots adapted for N-fixation symbioses, including presence of intracellular microbes. We also find structural and metagenomic evidence for mycorrhiza-like species of glomalean fungi (including Rhizophagus irregularis) not previously known for mosses, as well as ascomycete fungi (e.g. Rhizoscyphus ericae) that associate with other early-diverging plants. Because Takakia is the oldest known modern plant genus, this study of plants of a remote locale not strongly influenced by human activities may indicate microbiome features of early land plants.

Phyllosphere Microbiome

“…In both Sphagnum and Racomitrium lanuginosum (an abundant terrestrial mat-forming moss) bacterial communities are dominated by Pseudomonadota, Acidobacteriota, Actinomycetota, and Cyanobacteria (79,82). Takakia, a moss genus of what may be the earliest diverging land plants, hosts Alpha-and Betaproteobacteria capable of nitrogen fixation, in addition to their associations with ascomycete and glomalean (arbuscular-mycorrhizal) fungi, which form mycorrhizal-like structures (150).…”

Endofungal bacteria boost anthelminthic host protection with the biosurfactant symbiosin

“…[1][2][3][4] Omnipresent in all of the world's habitats, in marine environments, ora and soil biotopes, symbioses can inuence the diversity and composition of species in an ecological community and thus play a central role in the development and maintenance of an ecological system. [4][5][6][7][8] In mutualistic associations, partnerships that are benecial to all symbionts, different organisms live together and combine their individual skills to promote assertiveness or supply nutrients to the alliance. 3,9,10 While one partner may provide the food supply, 11,12 the other partner may possess the genomic abilities to biosynthesize a selection of natural products, such as communication molecules, UV-protectants or antibiotics.…”