T4-Related Bacteriophage LIMEstone Isolates for the Control of Soft Rot on Potato Caused by ‘Dickeya solani’

Abstract

The bacterium ‘Dickeya solani’, an aggressive biovar 3 variant of Dickeya dianthicola, causes rotting and blackleg in potato. To control this pathogen using bacteriophage therapy, we isolated and characterized two closely related and specific bacteriophages, vB_DsoM_LIMEstone1 and vB_DsoM_LIMEstone2. The LIMEstone phages have a T4-related genome organization and share DNA similarity with Salmonella phage ViI. Microbiological and molecular characterization of the phages deemed them suitable and promising for use in phage therapy. The phages reduced disease incidence and severity on potato tubers in laboratory assays. In addition, in a field trial of potato tubers, when infected with ‘Dickeya solani’, the experimental phage treatment resulted in a higher yield. These results form the basis for the development of a bacteriophage-based biocontrol of potato plants and tubers as an alternative for the use of antibiotics.

Phylogeny and classification of Dickeya based on multilocus sequence analysis

“…1) Dickeya multilocus sequence analysis (Adriaenssens et al, 2012;Van Vaerenbergh et al, 2012). Our MLSA supports the placement of these strains as a novel species clade within Dickeya, closely related to D. dieffenbachiae and D. dianthicola.…”

Isolation, characterization and complete genome sequence of PhaxI: a phage of Escherichia coli O157 : H7

“…From the O157 phages, AKFV33, Rv5, wV8, AR1, SFP10 and CBA120 are completely sequenced (GenBank accession numbers NC_017969.1, NC_011041.1, NC_ 012749.1, AP011113.1, HQ259103.1 and JN593240.1, respectively). Analysis of the PhaxI genome via BLASTN shows a high similarity to Viunalike phages, namely Salmonella phages ViI (Pickard et al, 2010), SFP10 (Park et al, 2012) and PhiSH19 (Hooton et al, 2011), Escherichia phage vB_EcoM_CBA120 , Shigella phage phiSboM-AG3 (Anany et al, 2011), and Dickeya phage vB_DsoM_LIMEstone1 (Adriaenssens et al, 2012b) (GenBank accession numbers FQ312032.1, HQ259103.1, JN126049.1, JN593240.1, FJ373894.1 and HE600015.1, respectively).…”

“…Its genome encodes a DNA polymerase, primase, helicase, ligase, primase-helicase, loader of helicase, clamp loader, sliding clamp, ssDNA-binding protein and topoisomerase subunits. All these genes are present in the genomes of the other six members of the genus 'Viunalikevirus' (Adriaenssens et al, 2012b;Anany et al, 2011;Hooton et al, 2011;Kutter et al, 2011;Park et al, 2012). These proteins have highest similarities with proteins of phages SFP10, CBA120 and PhiSH19, and lowest with AG3 and LIMEstone1.…”

Smart biologics for crop protection in agricultural systems

“…The table summarizes the results of phage trials that have been performed on a range of phytopathogens including Erwinia amylovora and Ralstonia solanacearum. However, field trials are biologically complex and the presence of other microbes and pathogens can influence the effectiveness of the phages when introduced into fields (Adriaenssens et al, 2012).…”