First Report of <i>Dickeya dianthicola</i> Causing Blackleg on Potato in Texas

Nasaruddin, A. S.; Charkowski, Amy O.; Babler, Brooke; Perna, Nicole T.; Glasner, Jeremy D.

doi:10.1094/pdis-01-19-0024-pdn

Cited by 10 publications

(3 citation statements)

References 4 publications

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“…Both E. tracheiphila and P. stewartii only occur in temperate Eastern North America—one of the world’s most intensively cultivated regions—despite global distribution of susceptible host plants 82 . D. dianthicola causes a virulent wilt disease and is emerging into cultivated potato crops, and is also geographically restricted to Eastern North America and Europe 83 – 85 . The exlx–gh5 gene architecture in Enterobacteriaceae, the gh5–exlx gene architecture in Xanthomonadaceae and cbm2–gh5–exlx gene architecture in C. michaganensis (Actinobacteria) is consistent with multiple independent co-occurrences of bacterial expansins with evolutionarily distinct gh5 domains, and may be an example of functional convergence.…”

Section: Discussionmentioning

confidence: 99%

A horizontally acquired expansin gene increases virulence of the emerging plant pathogen Erwinia tracheiphila

Rocha

Shapiro

Kolter

2020

Sci Rep

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Erwinia tracheiphila is a bacterial plant pathogen that causes a fatal wilt infection in some cucurbit crop plants. Wilt symptoms are thought to be caused by systemic bacterial colonization through xylem that impedes sap flow. However, the genetic determinants of within-plant movement are unknown for this pathogen species. Here, we find that E. tracheiphila has horizontally acquired an operon with a microbial expansin (exlx) gene adjacent to a glycoside hydrolase family 5 (gh5) gene. Plant inoculation experiments with deletion mutants in the individual genes (Δexlx and Δgh5) and the full operon (Δexlx–gh5) resulted in decreased severity of wilt symptoms, decreased mortality rate, and impaired systemic colonization compared to the Wt strain. Co-inoculation experiments with Wt and Δexlx–gh5 rescued the movement defect of the mutant strain, suggesting that expansin and GH5 function extracellularly. Together, these results show that expansin–GH5 contributes to systemic movement through xylem, leading to rapid wilt symptom development and higher rates of plant death. The presence of expansin genes in diverse species of bacterial and fungal wilt-inducing pathogens suggests that microbial expansin proteins may be an under-appreciated virulence factor for many pathogen species.

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Section: Discussionmentioning

confidence: 99%

A horizontally acquired expansin gene increases virulence of the emerging plant pathogen Erwinia tracheiphila

Rocha

Shapiro

Kolter

2020

Sci Rep

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“…Both of these pathogen species only occur in temperate Eastern North America – one of the world’s most intensively cultivated regions – despite global distrubtion of susceptible host plants (76). D. dianthicola causes a virulent wilt disease and is emerging into cultivated potato crops, and is also geographically restricted to Eastern North America and Europe (77-79).…”

Section: Discussionmentioning

confidence: 99%

A horizontally acquired expansin gene increases virulence of the emerging plant pathogenErwinia tracheiphila

Rocha

Shapiro

Kolter

2019

Preprint

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19 Author Contributions: JR and LRS conceived of the study. JR designed and conducted 20 molecular protocols and lab experiments. LRS conducted computational analyses and 21 performed experiments. JR, LRS and RK interpreted experimental data. JR and LRS 22 wrote the first draft of the manuscript, and JR, LRS and RK added critical revisions. 23 2 24 Data Deposition Statement: Analysis scripts and input files associated with 25 reconstruction of phylogenetic trees are available at 26 https://github.com/lshapiro31/gh5.expansin.phylogenetics 27 3 Abstract 28All land plants depend on proteins called 'expansins' that non-enzymatically loosen structural 29 cellulose, enabling cell wall extension during normal growth. Surprisingly, expansin genes are 30 also present -but functionally uncharacterized -in taxonomically diverse bacteria and fungi that 31 do not produce cellulosic cell walls. Here, we find that Erwinia tracheiphila 32 (Enterobacteriaceae), the causative agent of bacterial wilt of cucurbits, has horizontally acquired 33 an operon with a microbial expansin (exlx) gene and a glycoside hydrolase family 5 (gh5) gene. 34 E. tracheiphila is an unusually virulent plant pathogen that induces systemic wilt symptoms 35 followed by plant death, and has only recently emerged into cultivated cucurbit populations in 36 temperate Eastern North America. Plant inoculation experiments with deletion mutants show that 37 EXLX-GH5 is a secreted virulence factor that confers efficient xylem movement and 38 colonization ability to E. tracheiphila. Bacterial colonization of xylem blocks sap flow, inducing 39 wilt symptoms and causing plant death. Together, these results suggest that the horizontal 40 acquisition of the exlx-gh5 locus was likely a key step driving the recent emergence of E. 41 tracheiphila. The increase in E. tracheiphila virulence conferred by microbial expansins, the 42 presence of this gene in many other bacterial and fungal wilt-inducing plant pathogen species, 43 and the amenability of microbial expansins to horizontal gene transfer suggest this gene may be 44 an under-appreciated virulence factor in taxonomically diverse agricultural pathogens. 45 46 4 Importance 47Erwinia tracheiphila is a bacterial plant pathogen that causes a fatal wilt infection in cucurbit 48 crop plants. Here, we report that E. tracheiphila has horizontally acquired a microbial expansin 49 gene (exlx) adjacent to a glycoside hydrolase family 5 (gh5) gene. Expansins are predominantly 50 associated with plants due to their essential role in loosening structural cell wall cellulose during 51 normal growth. We find that the EXLX and GH5 proteins in E. tracheiphila function as a single 52 complex to facilitate xylem colonization, possibly by manipulating the size of xylem structures 53 that normally exclude the passage of bacteria. This suggests that horizontal acquisition of the 54 exlx-gh5 locus was likely a key step in the recent emergence of E. tracheiphila as an unusually 55 virulent plant pathogen. The presence of microbial expansin gene...

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“…Dickeya dianthicola [ 5 ] is now attributed to the devastating losses seen in Maine, New Jersey, and New York [ 5 , 13 , 15 , 16 ]. It has since been isolated in Texas and Hawaii [ 17 , 18 ]. Dickeya solani has not been isolated from any of the samples collected in 2015–2016.…”

Section: Introductionmentioning

confidence: 99%

Species of Dickeya and Pectobacterium Isolated during an Outbreak of Blackleg and Soft Rot of Potato in Northeastern and North Central United States

et al. 2021

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An outbreak of bacterial soft rot and blackleg of potato has occurred since 2014 with the epicenter being in the northeastern region of the United States. Multiple species of Pectobacterium and Dickeya are causal agents, resulting in losses to commercial and seed potato production over the past decade in the Northeastern and North Central United States. To clarify the pathogen present at the outset of the epidemic in 2015 and 2016, a phylogenetic study was made of 121 pectolytic soft rot bacteria isolated from symptomatic potato; also included were 27 type strains of Dickeya and Pectobacterium species, and 47 historic reference strains. Phylogenetic trees constructed based on multilocus sequence alignments of concatenated dnaJ, dnaX and gyrB fragments revealed the epidemic isolates to cluster with type strains of D. chrysanthemi, D. dianthicola, D. dadantii, P. atrosepticum, P. brasiliense, P. carotovorum, P. parmentieri, P. polaris, P. punjabense, and P. versatile. Genetic diversity within D. dianthicola strains was low, with one sequence type (ST1) identified in 17 of 19 strains. Pectobacterium parmentieri was more diverse, with ten sequence types detected among 37 of the 2015–2016 strains. This study can aid in monitoring future shifts in potato soft rot pathogens within the U.S. and inform strategies for disease management.

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First Report of Dickeya dianthicola Causing Blackleg on Potato in Texas

Cited by 10 publications

References 4 publications

A horizontally acquired expansin gene increases virulence of the emerging plant pathogen Erwinia tracheiphila

A horizontally acquired expansin gene increases virulence of the emerging plant pathogen Erwinia tracheiphila

A horizontally acquired expansin gene increases virulence of the emerging plant pathogenErwinia tracheiphila

Species of Dickeya and Pectobacterium Isolated during an Outbreak of Blackleg and Soft Rot of Potato in Northeastern and North Central United States

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