Demystifying the nomenclature of bacterial plant pathogens

Abstract

A unified approach to naming bacteria ensures accurate communication among scientists, regulators and the public. Rules for nomenclature, set out in the International Code of Nomenclature of Bacteria (ICNB), ensure that proposals for new names and combinations follow a logical and standardized progression that maintains the integrity of the established nomenclature while facilitating changes based on scientific inquiry into relationships among organisms. However, these Rules only apply to ranks at the level of subspecies and above and not to lower taxonomic ranks. The pathovar is one infraspecific rank that is widely used in the classification and nomenclature of plant pathogenic bacteria and is often included in legislation to provide statutory control of bacterial plant pathogens. Thus, phytobacteriologists must rely on two discontinuous but, complimentary systems: the Rules set forth in ICNB for naming down to subspecies level, and the Standards in the International Standards for Naming Pathovars of Plant Pathogenic Bacteria to name pathovars. A framework for determining the priority of names is provided by the Approved Lists of Bacterial Names, which gives genus, species and subspecies names and their corresponding type strains, and subsequent lists of validly published names appearing in the International Journal of Systematic and Evolutionary Microbiology. For pathovar names priority is based on the date of valid publication of legitimate names. A list of pathovar names and pathotype strains is maintained by the Committee on the Taxonomy of Plant Pathogenic Bacteria of the International Society of Plant Pathology. To help researchers avoid common pitfalls encountered when developing nomenclature for novel classification systems, this manuscript clarifies several key Rules and Standards. It aims to promote best practice, in that names developed to conform to the ICNB should also consider precedents set by previous nomenclatural designations as per the International Standards for Naming Pathovars of Plant Pathogenic Bacteria, thus ensuring continuity across the nomenclature of all phytopathogenic bacteria.