Definition of the novel symbiovar canariense within Mesorhizobium neociceri sp. nov., a new species of genus Mesorhizobium nodulating Cicer canariense in the Caldera de Taburiente National Park (La Palma, Canary Islands)

Cicer canariense is a highly promiscuous wild chickpea nodulated by Mesorhizobium strains in La Palma Island located at Canary archipelago. Four of these strains, CCANP34, CCANP35(T), CCANP38 and CCANP95 belong to a group phylogenetically close to Mesorhizobium caraganae with 100% similarity values in the 16S rRNA gene. However, the genomes of the strains CCANP35(T) and M. caraganae LMG 24397(T) obtained in this work showed ANIb and dDDH values of 90.02% and 44.1%, respectively. These values are lower than those currently accepted for different bacterial species showing that the Canarian strains do not belong to the species M. caraganae. The Canarian strains also differ from M. caraganae in the amounts of several fatty acids and in several phenotypic traits. Based on the obtained results the Canarian strains belong to a novel species for which we propose the name Mesorhizobium neociceri sp. nov. and whose type strain is CCANP35(T). The results of the phylogenetic analyses of nodC and nifH symbiotic genes showed that the Canarian strains represent a novel symbiovar within genus Mesorhizobium phylogenetically divergent to that encompassing M. caraganae. We propose the names canariense and caraganae for the symbiovars encompassing the strains of M. neociceri and M. caraganae, respectively. (C) 2021 Elsevier GmbH. All rights reserved.

Automated summary

A new species, Mesorhizobium neociceri sp. nov., was identified in wild chickpeas nodulated by Mesorhizobium strains in La Palma Island, Canary archipelago. The Canarian strains showed differences in genome, fatty acid content, and phenotypic traits compared to the existing species, Mesorhizobium caraganae. Additionally, phylogenetic analysis revealed a novel symbiovar within the genus Mesorhizobium divergent from M. caraganae.