Pectobacterium sinaloense sp. nov., a novel phytopathogenic species isolated from potato plants in Mexico

As part of a broader effort to survey and characterize the diversity of pectolytic bacteria affecting potato crops in Mexico, phytopathogenic strains were isolated from soft-rot symptoms on potato plants in Sinaloa. Among them, an atypical <i>Pectobacterium</i>-like strain, LFLA-215^T, could not be confidently assigned to any known species through biochemical or molecular methods. To clarify its taxonomic position and explore its genomic and functional features, whole-genome sequencing and comparative analyses were conducted, along with biochemical, morphological and pathogenicity evaluations. The strain LFLA-215^T is Gram-stain-negative, with peritrichous flagella, catalase-positive and oxidase-negative. Phylogenetic analyses based on the 16S rRNA operon, <i>dnaJ</i> and 923 core genes confirmed that strain LFLA-215^T and three additional strains (CFBP8739, CSR2 and CSR3) are members of the genus <i>Pectobacterium</i>. Although genomic similarity values between LFLA-215^T and other <i>Pectobacterium</i> species ranged from 87.73 to 93.53% (OrthoANI blast-based), 87.63-93.46% (OrthoANI USEARCH) and 34.0-52.1% (digital DNA-DNA hybridization), falling below species delineation thresholds, phylogenomic reconstructions consistently positioned all four strains within a coherent clade. This clade showed the closest relationship to '<i>Pectobacterium colocasium'</i> LJ1, whereas <i>Pectobacterium parmentieri</i> RNS 08-42-1A^T was the most distantly related. Although LFLA-215^T fulfilled Koch's postulates and demonstrated pathogenicity in potato plants, its virulence on tubers was comparatively lower than that of other known <i>Pectobacterium</i> strains, which could be related to the size and the reduction in the total number of genes when its complete genome is reported here. Our findings support the classification of the strains LFLA-215^T, CFBP8739, CSR2 and CSR3 as a novel species within the genus <i>Pectobacterium</i>, for which the name <i>Pectobacterium sinaloense</i> sp. nov. is proposed, with LFLA-215^T (=NCCB 101086=CM CNRG 1201=ATCC TSD-577) designated as the type strain.