Molecular Analysis of Bacterial Isolates From Necrotic Wheat Leaf Lesions Caused by , and Description of Three Putative Novel Species, sp. nov., sp. nov. and sp. nov.

is the etiological agent of the wheat bacterial leaf streak (BLS) disease. The isolation of this pathogen is usually based on the Wilbrink's-boric acid-cephalexin semi-selective medium which eliminates 90% of other bacteria, some of which might be novel species. In our study, a general purpose nutrient agar was used to isolate 49 bacterial strains including from necrotic wheat leaf tissues. Maximum likelihood cluster analysis of 16S rRNA sequences grouped the strains into 10 distinct genera. (32.7%) and (28.6%) were the dominant genera while and had 8.2%, each. and had two strains, each. BLAST and phylogenetic analyses of multilocus sequence analysis (MLSA) of specific housekeeping genes taxonomically assigned all the strains to validly described bacterial species, except three strains (10L4B, 12L4D and 32L3A) of and two (23L3C and 15L3B) of . Strains 10L4B and12L4D had as their closest known type strain while strain 32L3A was closest to . sp. strains 23L3C and 15L3B were closest to based on MLSA analysis. Our data on MLSA, whole genome-based cluster analysis, DNA-DNA hybridization and average nucleotide identity, matrix-assisted laser desorption/ionization-time-of-flight, chemotaxonomy and phenotype affirmed that these 5 strains constitute three novel lineages and are taxonomically described in this study. We propose the names, sp. nov. (type strain 23L3C = DOAB 1063 = CECT 30248 = LMG 32139), sp. nov. (type strain 32L3A = DOAB 1067 = CECT 30249 = LMG 32140) and sp. (type strain 10L4B = DOAB 1069 = CECT 30250 = LMG 32142). Comparative genomics of these novel species, relative to their closest type strains, revealed unique repertoires of core secretion systems and secondary metabolites/antibiotics. Also, the detection of CRISPR-Cas systems in the genomes of these novel species suggests an acquired mechanism for resistance against foreign mobile genetic elements. The results presented here revealed a cohabitation, within the BLS lesions, of diverse bacterial species, including novel lineages.