Variability within a clonal population of Erwinia amylovora disclosed by phenotypic analysis

Rafael J Mendes; Conceição Amaro; João Pedro Luz; Fernando Tavares; Conceição Santos

doi:10.7717/peerj.13695

Variability within a clonal population of Erwinia amylovora disclosed by phenotypic analysis

PeerJ. 2022 Jul 21:10:e13695. doi: 10.7717/peerj.13695. eCollection 2022.

Authors

Rafael J Mendes^{1

2

3

4

5}, Conceição Amaro⁶, João Pedro Luz⁶, Fernando Tavares^{1

4

5}, Conceição Santos^{1

2}

Affiliations

¹ Biology Department, Faculty of Sciences, University of Porto, Porto, Portugal.
² LAQV-REQUIMTE, Faculty of Sciences, University of Porto, Porto, Portugal.
³ CITAB, University of Trás-os-Montes e Alto Douro, Vila Real, Portugal.
⁴ CIBIO, Research Centre in Biodiversity and Genetic Resources, InBIO, Associated Laboratory, Campus Agrário de Vairão, Faculty of Sciences, University of Porto, Vairão, Portugal.
⁵ BIOPOLIS Program in Genomics, Biodiversity and Land Planning, CIBIO, Campus de Vairão, Vairão, Portugal.
⁶ QRural, School of Agriculture, Polytechnic Institute of Castelo Branco, Castelo Branco, Portugal.

Abstract

Background: Fire blight is a destructive disease of pome trees, caused by Erwinia amylovora, leading to high losses of chain-of-values fruits. Major outbreaks were registered between 2010 and 2017 in Portugal, and the first molecular epidemiological characterization of those isolates disclosed a clonal population with different levels of virulence and susceptibility to antimicrobial peptides.

Methods: This work aimed to further disclose the genetic characterization and unveil the phenotypic diversity of this E. amylovora population, resorting to MLSA, growth kinetics, biochemical characterization, and antibiotic susceptibility.

Results: While MLSA further confirmed the genetic clonality of those isolates, several phenotypic differences were recorded regarding their growth, carbon sources preferences, and chemical susceptibility to several antibiotics, disclosing a heterogeneous population. Principal component analysis regarding the phenotypic traits allows to separate the strains Ea 630 and Ea 680 from the remaining.

Discussion: Regardless the genetic clonality of these E. amylovora strains isolated from fire blight outbreaks, the phenotypic characterization evidenced a population diversity beyond the genotype clonality inferred by MLSA and CRISPR, suggesting that distinct sources or environmental adaptations of this pathogen may have occurred.

Conclusion: Attending the characteristic clonality of E. amylovora species, the data gathered here emphasizes the importance of phenotypic assessment of E. amylovora isolates to better understand their epidemiological behavior, namely by improving source tracking, make risk assessment analysis, and determine strain-specific environmental adaptations, that might ultimately lead to prevent new outbreaks.

Keywords: Carbon-use; Chemical-susceptibility; Fire blight; Genetic clonality; MLSA; Specific growth rate.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Anti-Bacterial Agents
Erwinia amylovora* / genetics
Fruit
Phenotype
Virulence / genetics

Substances

Anti-Bacterial Agents

Grants and funding

This work received financial support by public funds by Ministério da Ciência e Tecnologia –Fundação para a Ciência e a Tecnologia through the project financed with reference UIDB/50006/2020 — UIDP/50006/2020, and Rafael J. Mendes received support from Ministério da Ciência e Tecnologia –Fundação para a Ciência e a Tecnologia (grant number SFRH/BD/133519/2017). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.