A tale of two lineages: how the strains of the earliest divergent symbiotic Frankia clade spread over the world

• Published in: BMC genomics Vol. 23; no. 1; pp. 1 - 602
• Main Authors: Berckx, Fede, Nguyen, Thanh Van, Bandong, Cyndi Mae, Lin, Hsiao-Han, Yamanaka, Takashi, Katayama, Sae, Wibberg, Daniel, Blom, Jochen, Kalinowski, Jörn, Tateno, Masaki, Simbahan, Jessica, Liu, Chi-Te, Brachmann, Andreas, Pawlowski, Katharina
• Format: Journal Article
• Language: English
• Published: London BioMed Central Ltd 19-08-2022; BioMed Central; BMC
• Subjects: Actinorhizal symbiosis; Biodiversity; Biogeography; Clusters; Coriaria; Coriaria intermedia; Coriaria japonica; Dispersal; Dispersion; Evolution; Frankia; Genomes; Genomics; Gondwana; Host plants; Natural history; Nitrogen; Nitrogen fixation; Nitrogen-fixing microorganisms; Nitrogenation; Phylogenetics; Phylogeny; Root nodules; Southern Hemisphere; Symbiosis; New Zealand; Papua New Guinea; Japan; Philippines; Taiwan; India; Pakistan; Eurasia; Nepal; Gondwana
• ISSN: 1471-2164; 1471-2164
• DOI: 10.1186/s12864-022-08838-5

It is currently assumed that around 100 million years ago, the common ancestor to the Fabales, Fagales, Rosales and Cucurbitales in Gondwana, developed a root nodule symbiosis with a nitrogen-fixing bacterium. The symbiotic trait evolved first in Frankia cluster-2; thus, strains belonging to this cluster are the best extant representatives of this original symbiont. Most cluster-2 strains could not be cultured to date, except for Frankia coriariae, and therefore many aspects of the symbiosis are still elusive. Based on phylogenetics of cluster-2 metagenome-assembled genomes (MAGs), it has been shown that the genomes of strains originating in Eurasia are highly conserved. These MAGs are more closely related to Frankia cluster-2 in North America than to the single genome available thus far from the southern hemisphere, i.e., from Papua New Guinea.