RESUMO
Pectobacterium species are necrotrophic bacterial pathogens that cause soft rot diseases in potatoes and several other crops worldwide. Gene expression data identified Pectobacterium carotovorum subsp. carotovorum budB, which encodes the α-acetolactate synthase enzyme in the 2,3-butanediol pathway, as more highly expressed in potato tubers than potato stems. This pathway is of interest because volatiles produced by the 2,3-butanediol pathway have been shown to act as plant growth promoting molecules, insect attractants, and, in other bacterial species, affect virulence and fitness. Disruption of the 2,3-butanediol pathway reduced virulence of P. c. subsp. carotovorum WPP14 on potato tubers and impaired alkalinization of growth medium and potato tubers under anaerobic conditions. Alkalinization of the milieu via this pathway may aid in plant cell maceration since Pectobacterium pectate lyases are most active at alkaline pH.
Assuntos
Acetoína/metabolismo , Vias Biossintéticas , Pectobacterium carotovorum/metabolismo , Pectobacterium carotovorum/patogenicidade , Acetoína/farmacologia , Álcalis , Vias Biossintéticas/efeitos dos fármacos , Butileno Glicóis/farmacologia , Meios de Cultura/farmacologia , Perfilação da Expressão Gênica , Regulação Bacteriana da Expressão Gênica/efeitos dos fármacos , Genes Bacterianos/genética , Concentração de Íons de Hidrogênio/efeitos dos fármacos , Mutação/genética , Óperon/genética , Pectobacterium carotovorum/genética , Pectobacterium carotovorum/crescimento & desenvolvimento , Caules de Planta/efeitos dos fármacos , Caules de Planta/microbiologia , Tubérculos/efeitos dos fármacos , Tubérculos/microbiologia , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Solanum tuberosum/efeitos dos fármacos , Solanum tuberosum/microbiologia , Técnicas de Cultura de Tecidos , Virulência/efeitos dos fármacosRESUMO
Pectobacterium species cause disease worldwide in many crop and ornamental plants, including potato. A new Pectobacterium subspecies, P. carotovorum subsp. brasiliensis was recently described in Brazil and later found in the United States, Israel, and South Africa. Its virulence traits and host range remain unknown. A comparison of three taxa commonly found on potato showed that both P. carotovorum subsp. carotovorum and subsp. brasiliensis are more aggressive in causing tuber and stem soft rot than P. atrosepticum. Also, despite bacterial growth inhibition in vitro of P. carotovorum subsp. carotovorum and P. atrosepticum strains by P. carotovorum subsp. brasiliensis, this new subspecies and P. carotovorum subsp. carotovorum are able to co-colonize in the same infected tissue. Both subspecies were motile in lesions. Pathogenesis assays showed that host ranges of all three overlap, but are not identical. The host ranges of individual strains of P. carotovorum subsp. carotovorum and subsp. brasiliensis are limited, whereas P. atrosepticum can macerate many plant species in addition to potato. There was high variability in virulence assays with potato tuber; thus physiological factors were investigated. Tuber size, maturity, and field location had significant effects on susceptibility to soft rot, with larger, more mature tubers being more susceptible.
