Project description: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.
Project description:Transcription profiling of Nicotinan benthamiana in response to Pectobacterium carotovorum WPP14 and Pseudomonas syringae pv. tomato DC3000
Project description:Pectobacterium atrosepticum (Pba) is a gram-negative bacterium which causes blackleg and tuber soft rot on potato. To investigate the molecular processes and responses involved in Pba-host (potato) and Pba-non-host (radish) interactions, under laboratory conditions, we used total RNA-sequencing to measure the gene expression patterns from all three species. Samples from infected and non-infected plant roots were collected after fourteen days of inoculation with Pba SCRI_1039 and subjected to total RNA-sequencing on an Illumina sequencing platform.
Project description:Pectobacterium carotovorum ssp. carotovorum (Pcc) is a necrotrophic bacterial species that causes soft rot disease in Chinese cabbage. In this study, plants harboring the resistant mutant sr gene, which confers resistance against Pcc,were screened from an 800 M2 population mutated by ethyl methane sulfonate (EMS) and scored in vitro and in vivo for lesion size. The transcript profiles showed ~512 differentially expressed genes (DEGs) between sr and WT plants occurring between 6 and 12 h postinoculation (hpi), which corresponded to the important defense regulation period (resistance) to Pcc in Chinese cabbage. The downstream defense genes (CPK, CML, RBOH MPK3, and MPK4) of pathogen pattern-triggered immunity (PTI) were strongly activated during infection at 12 hpi in resistant mutant sr; PTI appears to be central to plant defense against Pcc via recognition by three putative pattern recognition receptors (PRRs; BrLYM1-BrCERK1, BrBKK1/SERK4-PEPR1, BrWAKs). Pcc triggered the upregulation of the jasmonic acid (JA) and ethylene (ET) biosynthesis genes in mutant sr, but auxins and other hormones may have affected some negative signals.Endogenous hormones (auxins, JAs, and SA), as well as exogenous auxins (MEJA and BTH), were also verified as functioning in the immune system. Concurrently, the expression of glucosinolate and lignin biosynthesis genes was increased at 12 hpi in resistant mutant sr, and the accumulation of glucosinolate and lignin also indicated that these genes have a functional defensive role against Pcc. Our study provides valuable information and elucidates the resistance mechanism of Chinese cabbage against Pcc infection.
Project description:This project aimed to investigate the transcriptomic differences between a Pectobacterium carotovorum wild-type strain (RC5297) and a derivative in which a restriction-modification system, termed PcaRCI, is knocked out. The aim was to identify genes whose expression might be regulated through methylation by the methyltransferase of the RM system.
Project description:Pectobacterium are Gram-negative rods of the family Pectobacteriaceae. They are the causative agent of soft rot diseases of crops and ornamental plants. However, their virulence mechanisms are not yet fully elucidated. Membrane vesicles (MVs) are universally released by bacteria and are be-lieved to play an important role in pathogenicity, and survival of bacteria in the environment. Our study investigates the role of MVs in the virulence of Pectobacterium. The results indicate that the morphology and yields of MVs depend on medium composition. In polygalacturonic acid (PGA) supplemented media, Pectobacterium produce MVs of a larger size (100-300 nm) apart of vesicles below 100 nm. Proteomic analyses revealed the presence of pectate degrading enzymes in MVs. The pectate plate test and enzymatic assay proved that those enzymes are active and able to de-grade pectates. What is more, pathogenicity test indicated that MVs derived from Pectobacterium were able to induce maceration of Zantedeschia sp. leaves. We also show that MVs of β-lactamase producing strains were able to suppress ampicillin activity and permit the growth of susceptible bacteria. Those findings indicate that MVs of Pectobacterium play an important role in host-pathogen interactions and niche competition with other bacteria. Our research also sheds some light on the mechanism of MVs production. We demonstrate that Pectobacterium strains, which overexpress the green fluorescence protein (GFP), produce more MVs than wild type strains. Moreover, proteomic analysis revealed that GFP was present in MVs. Therefore, we demonstrate that protein sequestration into MVs is not limited strictly to periplasmic proteins and is a common occurrence. Our research highlights the importance of MVs production as a mechanism of cargo delivery in Pectobacterium and an alternative secretion system.
Project description:Plant pathogens require lethal virulence factors, susceptible hosts, and optimal environmental conditions for disease establishment. High soil salinity, exacerbated by climate change, significantly impacts agro-biological ecosystems. However, the overall interactions between plant pathogens and salt stress are not fully characterized or understood. This study examines the effects of salt stress on representative plant pathogens: Burkholderia gladioli, Pectobacterium carotovorum subsp. carotovorum, and Ralstonia solanacearum. Using pan-genome-based comparative transcriptomics, we analyzed the comprehensive alterations within the biological systems of plant pathogens when treated with 200 mM NaCl. Our results highlight the differential responses between salt-sensitive and salt-tolerant pathogens to salt stress.