Recommendations for naming plant pathogenesis-related proteins

Pathogenesis-related proteins (abbreviated PRs) are defined as plant proteins that are induced in pathological or related situations. We propose a unifying nomenclature for PRs based on their grouping into families sharing amino acid sequences, serological relationship, and/or enzymatic or biological activity. The nomenclature classifies novel proteins identified by electrophoresis or chromatography along with those established by other workers. The previously proposed system of the five well-established families from tobacco is extended to accommodate a further six families. Families are indicated by arabic numerals and individual members are named by lower case letters in the order in which they are described. Additional rules are proposed to deal with forms containing more than a single polypeptide and as yet unclassified PRs. PR genes whose sequences are conserved but whose designations are not based on function are to be designated Ypr in accordance with the recommendations of the Commission on Plant Gene Nomenclature.