Hornwort

Anthoceros Spp.

Anthoceros at UZH BLAST Genome Browser Downloads Expression Atlas

Hornworts comprise a bryophyte lineage that diverged from other extant land plants >400 million years ago and bears unique biological features, including a distinct sporophyte architecture, cyanobacterial symbiosis and a pyrenoid-based carbon-concentrating mechanism (CCM). Here are its main characteristics:

  • Thalloid Structure: It has a flattened, lobed thallus (the plant body) that grows on moist soil surfaces. The thallus contains cavities where cyanobacteria live in symbiosis, helping with nitrogen fixation.
  • Symbiosis with Cyanobacteria: A. agrestis forms a mutualistic relationship with nitrogen-fixing cyanobacteria, specifically Nostoc, which live in specialized chambers in the thallus. This relationship is important for nutrient acquisition, particularly in nutrient-poor environments.
  • Horn-like Sporophyte: A key characteristic of hornworts, including A. agrestis, is their elongated, horn-shaped sporophyte, which remains attached to the gametophyte and grows continuously. This is different from most other bryophytes where the sporophyte is typically short-lived.
  • Reproduction: A. agrestis can reproduce both sexually and asexually. Sexually, it produces antheridia (male structures) and archegonia (female structures), leading to the formation of spores in the sporophyte. Asexually, it can form gemmae, small reproductive bodies that can grow into new plants.
  • Ecological Role: It plays a significant role in early succession in disturbed or bare soil environments, where it contributes to soil stabilization and nitrogen cycling due to its cyanobacterial symbiosis.
  • Model for Evolutionary Studies: As a member of an ancient plant lineage, A. agrestis is valuable for studying the evolution of plant development and physiology, especially in comparison to vascular plants.

These characteristics make Anthoceros spp. interesting species for understanding plant evolution and the relationships between plants and microbial symbionts.

The available Anthoceros genomes were published at Li et al. 2020.

Genome assembly stats

Estimated genome size (Mb) Assembled genome size (Mb) Contig/scaffold number Contig/scaffold N50 length Assembly approach
A. agrestis Bonn 122–132 116.9 1577/322 155.5 kb/17.3 Mb Illumina + Nanopore + Hi-C
A. agrestis Oxford 123–135 122.9 153/– 1.8 Mb/– Nanopore + Illumina
A. punctatus 128–150 132.8 202/– 1.7 Mb/– Nanopore + Illumina

Taxonomy

Kingdom Viridiplantae
Phylum Streptophyta
Class Anthoceropsida
Order Anthocerotales
Family Anthocerotaceae
Genus Anthoceros L.
Species Anthoceros agrestis Paton