Unknown,Transcriptomics,Genomics,Proteomics

Dataset Information

RNA-seq of Pectobacterium carotovorum subsp. carotovorum and P. polaris infecting potato at 24, 48 and 72 hpi, and grown on M9 solid minimal medium at 24 hpi

ABSTRACT: Importance: Pectobacterium species cause soft rot in potato and other host plants primarily by secreting a battery of plant cell wall degrading enzymes. In addition, several different secretion systems are mobilized during infection. Previous studies of gene expression and regulation thereof primarily focused on the onset of infection. This work investigated transcriptome changes in Pectobacterium during the infection of potato tubers up to 72 hours post inoculation to elucidate biological processes during a longer infection period. Methods: The transcriptomes of aggressive strains of the two species P. carotovorum subsp. carotovorum and P. polaris were investigated during infection of potato minitubers (cv. 'Asterix') at 24, 48 and 72 hours after inoculation by RNA sequencing. The transcriptomes were compared to that of bacteria grown on minimal M9 medium, and transcriptomes from later infection time points (48 and 72 hours after inoculation) were compared to early infection (24 hours after inoculation). Results: Plant cell wall degrading enzymes and secretion system associated genes were largely upregulated during infection compared to in vitro growth, but downregulated in the later phases of infection compared to the early infection phase. The downregulation was not sufficiently explained by the expression of known virulence regulators such as the RsmA/B or the ExpA/S systems.

INSTRUMENT(S): Illumina HiSeq 2500

ORGANISM(S): Pectobacterium polaris

SUBMITTER: Merete Wiken Dees

PROVIDER: E-MTAB-7921 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Posttranscriptional regulator RsmA is part of a regulatory system that controls production of plant cell wall degrading enzymes (PCWDEs), motility and other virulence factors among the Pectobacterium spp of plant pathogens. We constructed the knockout mutation of rsmA gene in Pectobacterium wasabiae strain SCC3193. The rsmA- strain has three times lower growth rate but increased virulence when compared to wild type. To explain this phenotype we compared wild type and rsmA- mRNA levels using genome wide microarray. We found that the synthesis of all known virulence factors and flagella is upregulated, while cell division and peptidoglycan synthesis is down regulated in rsmA- strain. The TCA cycle is directed fully to energy production, indicating low energetic status of the cell that is a probable reason for the low growth rate of the mutant. Growth experiments showed that the enzymatic activities of extracellular virulence factors polygalacturonase and pectate lyase are very high throughout the growth curve even without induction by plant component. Wild type cells are rod shaped in liquid media, but elongated and hyperflagellated in swarm plate containing potato tuber extract and in potato tuber. The rsmA- strain exhibits the same conditional phenotype, but differentiation into swarmer cells is faster and cell elongation more pronounced. Virulence experiments in potato tuber showed that although rsmA- strain causes bigger tissue maceration, its ability to compete with the natural bacterial community in the host is decreased. We conclude that the lack of RsmA switches the cells to infective phenotype characterized by expression of virulence factors and swarming. The lack of control over these energy costly processes is probably the reason for decreased growth rate and fitness. Gene expression analysis from P. wasabie SCC3193 wildtype and SCC3193 rsmA mutant was performed on RNA samples extraxcted from the rsmA mutant (at 40 and 48 hours) and wildtype (at 24 hours). The strain were grown on 1.5% agar M9 minimal media plates supplemented with 10% potato extract. Three biological replicates were used from each strain at each time point.

Dataset Information

RNA-seq of Pectobacterium carotovorum subsp. carotovorum and P. polaris infecting potato at 24, 48 and 72 hpi, and grown on M9 solid minimal medium at 24 hpi

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