Symbiosis islands of Loteae-nodulating Mesorhizobium comprise three radiating lineages with concordant nod gene complements and nodulation host-range groupings.
MetadataShow full item record
© 2020 The Authors
Mesorhizobium is a genus of soil bacteria, some isolates of which form an endosymbiotic relationship with diverse legumes of the Loteae tribe. The symbiotic genes of these mesorhizobia are generally carried on integrative and conjugative elements termed symbiosis islands (ICESyms). Mesorhizobium strains that nodulate Lotus spp. have been divided into host-range groupings. Group I (GI) strains nodulate L. corniculatus and L. japonicus ecotype Gifu, while group II (GII) strains have a broader host range, which includes L. pedunculatus. To identify the basis of this extended host range, and better understand Mesorhizobium and ICESym genomics, the genomes of eight Mesorhizobium strains were completed using hybrid long- and short-read assembly. Bioinformatic comparison with previously sequenced mesorhizobia genomes indicated host range was not predicted by Mesorhizobium genospecies but rather by the evolutionary relationship between ICESym symbiotic regions. Three radiating lineages of Loteae ICESyms were identified on this basis, which correlate with Lotus spp. host-range grouping and have lineage-specific nod gene complements. Pangenomic analysis of the completed GI and GII ICESyms identified 155 core genes (on average 30.1 % of a given ICESym). Individual GI or GII ICESyms carried diverse accessory genes with an average of 34.6 % of genes unique to a given ICESym. Identification and comparative analysis of NodD symbiotic regulatory motifs - nod boxes - identified 21 branches across the NodD regulons. Four of these branches were associated with seven genes unique to the five GII ICESyms. The nod boxes preceding the host-range gene nodZ in GI and GII ICESyms were disparate, suggesting regulation of nodZ may differ between GI and GII ICESyms. The broad host-range determinant(s) of GII ICESyms that confer nodulation of L. pedunculatus are likely present amongst the 53 GII-unique genes identified.
Showing items related by title, author, creator and subject.
High-quality permanent draft genome sequence of the Bradyrhizobium elkanii type strain USDA 76<sup>T</sup>, isolated from Glycine max (L.) MerrReeve, W.; van Berkum, P.; Ardley, J.; Tian, R.; Gollagher, M.; Marinova, Dora; Elia, P.; Reddy, T.; Pillay, M.; Varghese, N.; Seshadri, R.; Ivanova, N.; Woyke, T.; Baeshen, M.; Baeshen, N.; Kyrpides, N. (2017)Â© 2017 The Author(s). Bradyrhizobium elkanii USDA 76 T (INSCD = ARAG00000000), the type strain for Bradyrhizobium elkanii, is an aerobic, motile, Gram-negative, non-spore-forming rod that was isolated from an effective ...
The genetics of symbiotic nitrogen fixation: Comparative genomics of 14 rhizobia strains by resolution of protein clustersBlack, M.; Moolhuijzen, Paula; Chapman, B.; Barrero, R.; Howieson, J.; Hungria, M.; Bellgard, M. (2012)The symbiotic relationship between legumes and nitrogen fixing bacteria is critical for agriculture, as it may have profound impacts on lowering costs for farmers, on land sustainability, on soil quality, and on mitigation ...
Haskett, T.; Ramsay, Joshua; Bekuma, A.; Sullivan, J.; O'Hara, G.; Terpolilli, J. (2017)Integrative and conjugative elements (ICEs) are generally regarded as regions of contiguous DNA integrated within a bacterial genome that are capable of excision and horizontal transfer via conjugation. We recently ...