Labedella phragmitis sp. nov. and Labedella populi sp. nov., two endophytic actinobacteria isolated from plants in the Taklamakan Desert and emended description of the genus Labedella

Two novel strains, designated 11W25H-1T and 8H24J-4-2T, were isolated from surface-sterilized plant tissues collected from the Taklamakan Desert in the Xinjiang Uygur Autonomous Region, China. The strains were characterized by a polyphasic approach in order to clarify their taxonomic positions. They were Gram-stain positive, aerobic, non-motile, non-spore-forming and rod-shaped. The 16S rRNA gene sequences of the strains showed highest similarities with Labedella gwakjiensis KCTC 19176T (99.2% and 98.9%, respectively) and Labedella endophytica CPCC 203961T (98.9% and 99.0%, respectively). The sequence similarity between strains 11W25H-1T and 8H24J-4-2T was 99.4%. Phylogenetic analyses based on 16S rRNA gene sequences and single-copy phylogenetic marker genes (pMGs) showed that the two strains belonged to the genus Labedella and formed a separate cluster from the closest species L. gwakjiensis KCTC 19176T and L. endophytica CPCC 203961T. Genomic analyses, including average nucleotide identity (ANI) and digital DNA–DNA hybridization (dDDH), clearly separated the strains from each other and from the other species of the genus Labedella with values below the thresholds for species delineation. The two strains showed chemotaxonomic characteristics and phenotypic properties in agreement with the description of the genus Labedella and also confirmed the differentiation from the closest species. The data demonstrated that strains 11W25H-1T and 8H24J-4-2T represented two novel species of the genus Labedella, for which the names Labedella phragmitis sp. nov. (type strain 11W25H-1T=JCM 33144T=CGMCC 1.16700T) and Labedella populi sp. nov. (type strain 8H24J-4-2T=JCM 33143T=CGMCC 1.16697T) are proposed.