Proposal to reclassify Brenneria quercina (Hildebrand and Schroth 1967) Hauben et al. 1999 into a new genus, Lonsdalea gen. nov., as Lonsdalea quercina comb. nov., descriptions of Lonsdalea quercina subsp. quercina comb. nov., Lonsdalea quercina subsp. iberica subsp. nov. and Lonsdalea quercina subsp. britannica subsp. nov., emendation of the description of the genus Brenneria , reclassification of Dickeya dieffenbachiae as Dickeya dadantii subsp. dieffenbachiae comb. nov., and emendation of the description of Dickeya dadantii

Abstract

Bacterial isolates from oak trees in Spain and Britain, showing symptoms of bark canker and Acute Oak Decline (AOD), respectively, were examined by a polyphasic approach. Both 16S rRNA gene sequencing and multilocus sequence analysis (MLSA), based on partial sequences of gyrB, rpoB, infB and atpD genes, revealed that the isolates were separated into two genetic groups according to their origin. Their closest phylogenetic relative was Brenneria quercina , the causal agent of drippy nut disease of oak, which clustered distant to the other species of the genus Brenneria . MLSA data for species of the genera Brenneria , Pectobacterium , Dickeya , Erwinia , Pantoea and Samsonia confirmed the polyphyletic nature of the genus Brenneria and indicated synonymy of Dickeya dadantii and Dickeya dieffenbachiae . DNA–DNA hybridization experiments confirmed this synonymy and also revealed DNA–DNA relatedness values of 58–73 % between the new oak isolates and B. quercina . Phenotypic and/or chemotaxonomic methods allowed B. quercina and the two genetic groups of new oak isolates to be discriminated from other recognized species of the genus Brenneria and from members of the closely related genera Dickeya , Pectobacterium and Samsonia . Based on the data obtained, the following taxonomic proposals are made: (1) reclassification of B. quercina as the type species of a novel genus, Lonsdalea gen. nov., as Lonsdalea quercina comb. nov. (type strain LMG 2724T = ATCC 29281T = CCUG 48867T = CFBP 3617T = CIP 105201T = DSM 4561T = ICMP 1845T), (2) classification of the oak isolates as Lonsdalea quercina subsp. iberica subsp. nov. (type strain LMG26264T = NCPPB 4490T) and Lonsdalea quercina subsp. britannica subsp. nov. (type strain LMG 26267T = NCPPB 4481T) and leading to the automatic creation of Lonsdalea quercina subsp. quercina subsp. nov. (type strain LMG 2724T = ATCC 29281T), (3) emendation of the description of the genus Brenneria , and (4) reclassification of Dickeya dieffenbachiae as Dickeya dadantii subsp. dieffenbachiae comb. nov. (type strain LMG 25992T = CFBP 2051T), with the automatic creation of Dickeya dadantii subsp. dadantii subsp. nov. (type strain LMG 25991T = CFBP 1269T).