Dickeya colocasiae sp. nov. isolated from wetland taro, Colocasia esculentum

Abstract

Bacterial pathogens identified as Dickeya sp. have recently been associated with a corm rot of wetland taro on Oahu, Hawaii, but the species designation of these strains was unclear. A Gram-negative, pectinolytic bacterial strain PL65T isolated from an infected taro corm was subjected to polyphasic analysis to determine its genomic and phenotypic characteristics. Multi-locus sequence analyses (MLSA) based on five housekeeping genes (dnaA, gapA, gyrB, atpD, and purA) revealed that Dickeya zeae and D. oryzae, were the closest relatives. Phylogenetic analysis based on 463 core gene sequences clearly showed two potentially new species within Dickeya oryzae. In silico DNA- DNA hybridization value of strain PL65T with 12 Type strains of Dickeya species was <68%. Average nucleotide identity (ANI) analysis revealed that PL65T was at the margin of the species delineation cut-off values with a 96% ANI value. The metabolic profile of strain PL65T using BIOLOG differentiated it from the type strains of all other known species of Dickeya. Based on the results of genome-to-genome comparisons and phenotypic data presented in this report, we propose establishment of a new species, Dickeya colocasiae sp. nov. with strain PL65T as the type strain (ICMP 24361T).