Biocontrol of the Potato Blackleg and Soft Rot Diseases Caused by Dickeya dianthicola
ABSTRACTDevelopment of protection tools targetingDickeyaspecies is an important issue in the potato production. Here, we present the identification and the characterization of novel biocontrol agents. Successive screenings of 10,000 bacterial isolates led us to retain 58 strains that exhibited growth inhibition properties against severalDickeyasp. and/orPectobacteriumsp. pathogens. Most of them belonged to thePseudomonasandBacillusgenera.In vitroassays revealed a fitness decrease of the testedDickeyasp. andPectobacteriumsp. pathogens in the presence of the biocontrol agents. In addition, four independent greenhouse assays performed to evaluate the biocontrol bacteria effect on potato plants artificially contaminated withDickeya dianthicolarevealed that a mix of three biocontrol agents, namely,Pseudomonas putidaPA14H7 andPseudomonas fluorescensPA3G8 and PA4C2, repeatedly decreased the severity of blackleg symptoms as well as the transmission ofD. dianthicolato the tuber progeny. This work highlights the use of a combination of biocontrol strains as a potential strategy to limit the soft rot and blackleg diseases caused byD. dianthicolaon potato plants and tubers.