RESUMO
Dickeya solani is a pathogen most frequently responsible for infecting potato plants in Europe. As in the case of most plant pathogens, its ability to colonize and invade the host depends on chemotaxis and motility. The coordinated movement of Dickeya over solid surfaces is governed by a quorum sensing mechanism. In D. solani motility is regulated by ExpI-ExpR proteins, homologous to luxI-luxR system from Vibrio fisheri, in which N-acyl-homoserine lactones (AHLs) serve as signaling molecules. Moreover, in many Gram-negative bacteria motility is coupled with central metabolism via carbon catabolite repression. This enables them to reach more nutrient-efficient niches. The aim of this study was to analyze the swarming motility of D. solani depending on the volume of the medium in the cultivation plate and glucose content. We show that the ability of this bacterium to move is strictly dependent on both these factors. Moreover, we analyze the production of AHLs and show that the quorum sensing mechanism in D. solani is also influenced by the availability of glucose in the medium and that the distribution of these signaling molecules are different depending on the volume of the medium in the plate.
Assuntos
Acil-Butirolactonas/farmacologia , Proteínas de Bactérias/genética , Dickeya/efeitos dos fármacos , Glucose/farmacologia , Solanum tuberosum/microbiologia , Fatores de Virulência/genética , Acil-Butirolactonas/metabolismo , Proteínas de Bactérias/metabolismo , Quimiotaxia/efeitos dos fármacos , Quimiotaxia/genética , Meios de Cultura/química , Meios de Cultura/farmacologia , Dickeya/genética , Dickeya/metabolismo , Dickeya/patogenicidade , Regulação Bacteriana da Expressão Gênica , Glucose/metabolismo , Doenças das Plantas/microbiologia , Percepção de Quorum/efeitos dos fármacos , Percepção de Quorum/genética , Proteínas Repressoras/genética , Proteínas Repressoras/metabolismo , Transativadores/genética , Transativadores/metabolismo , Fatores de Virulência/metabolismoRESUMO
Bacterial soft rot caused by the bacteria Dickeya and Pectobacterium is a destructive disease of vegetables, as well as ornamental plants. Several management options exist to help control these pathogens. Because of the limited success of these approaches, there is a need for the development of alternative methods to reduce losses. In this study, we evaluated the effect of potassium tetraborate tetrahydrate (PTB) on the growth of six Dickeya and Pectobacterium spp. Disc diffusion assays showed that Dickeya spp. and Pectobacterium spp. differ in their sensitivity to PTB. Spontaneous PTB-resistant mutants of Pectobacterium were identified and further investigation of the mechanism of PTB resistance was conducted by full genome sequencing. Point mutations in genes cpdB and supK were found in a single Pectobacterium atrosepticum PTB-resistant mutant. Additionally, point mutations in genes prfB (synonym supK) and prmC were found in two independent Pectobacterium brasiliense PTB-resistant mutants. prfB and prmC encode peptide chain release factor 2 and its methyltransferase, respectively. We propose the disruption of translation activity due to PTB leads to Pectobacterium growth inhibition. The P. atrosepticum PTB-resistant mutant showed altered swimming motility. Disease severity was reduced for P. atrosepticum-inoculated potato stems sprayed with PTB. We discuss the potential risk of selecting for bacterial resistance to this chemical.