Rathayibacter agropyri (non O'Gara 1916) comb. nov., nom. rev., isolated from western wheatgrass (Pascopyrum smithii)

Aplanobacter agropyri was first described in 1915 by O'Gara and later transferred to the genus Corynebacterium by Burkholder in 1948 but it was not included in the Approved Lists of Bacterial Names in 1980 and, consequently, is not recognized as a validly published species. In the 1980s, bacteria resembling Corynebacterium agropyri were isolated from plant samples stored at the Washington State Mycological Herbarium and from a diseased wheatgrass plant collected in Cardwell, Montana, USA. In the framework of this study, eight additional isolates were recovered from the same herbarium plant samples in 2011. The isolates are slow-growing, yellow-pigmented, Gram-stain-positive and coryneform. The peptidoglycan is type B2γ containing diaminobutyric acid, alanine, glycine and glutamic acid, the cell-wall sugars are rhamnose and mannose, the major respiratory quinone is MK-10, and the major fatty acids are anteiso-15 : 0, anteiso 17 : 0 and iso-16 : 0, all of which are typical of the genus Rathayibacter. Phylogenetic analysis of 16S rRNA gene sequences placed the strains in the genus Rathayibacter and distinguished them from the six other described species of Rathayibacter. DNA-DNA hybridization confirmed that the strains were members of a novel species. Based on phenotypic, chemotaxonomic and phylogenetic characterization, it appears that strains CA-1 to CA-12 represent a novel species, and the name Rathayibacter agropyri (non O'Gara 1916) comb. nov., nom. rev. is proposed; the type strain is CA-4^T (=DSM 104101^T;=ATCC TSD-78^T).