Identification of antibacterial type 6 sectretion system effectors in pectobacterium carotovorum subsp. Brasiliense 1692
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University of Pretoria
Abstract
Pectobacterium carotovorum subsp. brasiliense 1692 is an economically important pathogen as
it causes soft rot and blackleg of numerous agricultural crops, especially potato, in South Africa
and in other parts of the world. In a multicellular environment, microorganisms interact with each
other and protein secretion systems mediate many of these interactions. Survival often requires
competitive interactions against closely and distantly related species. Although initially identified
as an antieukaryotic virulence factor, the T6SS has mainly been implicated in interbacterial
competition. Studies have shown that the T6SS of Pectobacterium carotovorum ssp. brasiliense
1692 (Pcb1692) is significantly upregulated upon in planta infection; however, the precise role
during infection remains unknown. In this study, the role of the T6SS in Pcb1692 was investigated.
In planta potato leaf competition assays indicate that no observable competition was mediated by
the T6SS in Pcb1692. As the majority of T6SSs are involved in bacterial competition, a
bioinformatics approach was used to identify whether the lack of T6SS-mediated competition was
due to an absence of antibacterial effectors within the genome. Upon discovery of a number of
putative antibacterial effectors, these were cloned and ectopically expressed in E. coli. Results
indicate that individual expression of effectors, except the AHH nuclease, does not contribute
towards bacterial growth inhibition. Altogether, this study has provided insight into the
antibacterial role of the T6SS of Pcb1692, and results indicate that although the T6SS is
significantly upregulated during infection, bacterial competition is not its foremost role within
potato leaves.
Description
Dissertation (MSc)--University of Pretoria, 2020.
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UCTD
Sustainable Development Goals
Citation
Miguel, N 2020, Identification of antibacterial type 6 sectretion system effectors in pectobacterium carotovorum subsp. Brasiliense 1692, MSc Dissertation, University of Pretoria, Pretoria, viewed yymmdd <http://hdl.handle.net/2263/77854>