The hornwort genome and early land plant evolution

Abstract

Hornworts, liverworts and mosses are three early diverging clades of land plants, and together comprise the bryophytes. Here, we report the draft genome sequence of the hornwort Anthoceros angustus. Phylogenomic inferences confirm the monophyly of bryophytes, with hornworts sister to liverworts and mosses. The simple morphology of hornworts correlates with low genetic redundancy in plant body plan, while the basic transcriptional regulation toolkit for plant development has already been established in this early land plant lineage. Although the Anthoceros genome is small and characterized by minimal redundancy, expansions are observed in gene families related to RNA editing, UV protection and desiccation tolerance. The genome of A. angustus bears the signatures of horizontally transferred genes from bacteria and fungi, in particular of genes operating in stress-response and metabolic pathways. Our study provides insight into the unique features of hornworts and their molecular adaptations to live on land.

Draft genome of the aquatic mossFontinalis antipyretica(Fontinalaceae, Bryophyta)

“…With the streptophyte alga K. nitens rooted as the outgroup, bryophytes were confirmed as a monophyletic group, and sister to the vascular plant S. moellendorffii. Within bryophytes, hornwort is sister to liverworts and mosses, which is consistent with previous studies [29]. The 6 four mosses formed a clade, the newly sequenced F. antipyretica and another Hypnales species P. schreberi clustered as one clade (Fig.…”

“…Reconstructions of the relationships of extant land plant lineages are converging on a scenario wherein bryophytes compose a sister lineage to living vascular plants, with mosses and liverworts sharing a unique common ancestor that arose from a split from the ancestor giving rise to hornworts [31]. Following the recent release of the hornwort genomes [29,32], gene and gene family evolution among bryophytes can be assessed within a robust phylogenetic framework.…”

A mycorrhizae-like gene regulates stem cell and gametophore development in mosses

“…The PpMACRO2 protein includes a single macro2 domain of 145 aa, with an additional N-terminus of 97 aa and a short C-terminus of about 64 aa. With the PpMACRO2 protein sequence (Genbank accession number: XP_024388278) as query, we performed a BLAST search of the NCBI non-redundant (nr) protein sequence database, the 1000 plants project (OneKP) and other resources, including the recently published genomes of hornworts (Anthoceros angustus), ferns (Azolla filiculoides and Salvinia cucullata) and charophytes (e.g., Chara braunii, Spirogloea muscicola, Mesotaenium endlicherianum, Mesostigma viride, and Chlorokybus atmophyticus) [23][24][25][26][27][28] , as well as our internal draft genome of another charophyte, Interfilum paradoxum. Additional pHMMER search was performed against Reference Proteomes.…”

“…This second scenario is not only consistent with the common belief that physical association, such as symbiosis, often facilitates horizontal gene transfer (HGT), but also supported by the amino acid residues uniquely shared by Mucoromycota and bryophyte sequences. Thus far, HGT in eukaryotes remains hotly debated 64,65 but has been reported in many eukaryotic lineages [66][67][68] , and foreign genes have also been documented in bryophytes and their charophyte relatives 6,25,27,69 . The vast majority of the documented foreign genes in bryophytes and charophytes, however, have not been investigated experimentally.…”

A study of male fertility control in Medicago truncatula uncovers an evolutionarily conserved recruitment of two tapetal bHLH subfamilies in plant sexual reproduction

“…(2017) and J. Zhang et al . (2020) respectively. Complete datasets of full‐length protein sequences containing the bHLH domain from five genomes (tomato, Vitis vinifera, Dioscorea rotundata , maize and Amborella trichopoda ) were identified through B lastp searches from the Phytozome.…”