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11 pages, 2880 KiB

Open AccessArticle

Field Use of Protective Bacteriophages against Pectinolytic Bacteria of Potato

by Karel Petrzik, Josef Vacek, Martin Kmoch, Denisa Binderová, Sára Brázdová, Ondřej Lenz and Rudolf Ševčík

Microorganisms 2023, 11(3), 620; https://doi.org/10.3390/microorganisms11030620 - 28 Feb 2023

Cited by 3 | Viewed by 1689

Abstract

The pectinolytic Dickeya solani bacterium is an important pathogen found in potatoes. We conducted laboratory and field experiments mimicking severe and mild Dickeya spp. infection and investigated the application of a mixture of two lytic bacteriophages before and after bacterial infection to protect [...] Read more.

The pectinolytic Dickeya solani bacterium is an important pathogen found in potatoes. We conducted laboratory and field experiments mimicking severe and mild Dickeya spp. infection and investigated the application of a mixture of two lytic bacteriophages before and after bacterial infection to protect the plants. Application of the phage solution to tuber disks and wounded tubers did not completely eliminate the infection but reduced the development of soft rot symptoms by 59.5–91.4%, depending on the phage concentration. In the field trial, plants treated with bacteriophages after severe Dickeya infection had 5–33% greater leaf cover and 4–16% greater tuber yield compared to untreated plants. When simulating a mild infection, leaf cover was 11–42% greater, and tuber yield was 25–31% greater compared to untreated plants. We conclude that the phage mixture has the potential to protect potatoes ecologically from D. solani. Full article

(This article belongs to the Special Issue Dickeya and Pectobacterium: Ecology, Pathology and Plant Protection 2.0)

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15 pages, 2659 KiB

Open AccessArticle

Increase of Glycoalkaloid Content in Potato Tubers by Greening as a Method to Reduce the Spread of Pectobacterium and Dickeya spp. in Seed Production Systems

by Dorota Sołtys-Kalina, Anna Grupa-Urbańska, Renata Lebecka, Maud Tallant, Isabelle Kellenberger and Brice Dupuis

Microorganisms 2023, 11(3), 605; https://doi.org/10.3390/microorganisms11030605 - 27 Feb 2023

Cited by 1 | Viewed by 1802

Abstract

Dickeya and Pectobacterium species are the causal agents of blackleg and soft rot diseases. This article explores the possibility of using the glycoalkaloids (GAs) naturally produced by the potato tuber after the greening process as a blackleg control method. We first tested the [...] Read more.

Dickeya and Pectobacterium species are the causal agents of blackleg and soft rot diseases. This article explores the possibility of using the glycoalkaloids (GAs) naturally produced by the potato tuber after the greening process as a blackleg control method. We first tested the effect of GAs extracted from four potato cultivars on the growth and viability of one Dickeya and one Pectobacterium strain in growth media. Then, four years of field experiments were performed in which the incidence of blackleg was assessed in plants grown from the seed tubers of cv. Agria that were subjected to various greening treatments. In the growth media, all GAs isolated from the four cultivars appeared to be bacteriostatic and bactericidal against both bacteria strains. The inhibitory effect varied among GAs from different cultivars. Except for a one-year field trial, the blackleg incidence was lower in plants grown from green seed tubers without the yield being affected. The blackleg control was marginal, probably due to the low production of GAs by the tubers of cv. Agria after greening. Based on our findings, seed tuber greening has a good potential for blackleg control after the identification of varieties that present optimal GA composition after greening. Full article

(This article belongs to the Special Issue Dickeya and Pectobacterium: Ecology, Pathology and Plant Protection 2.0)

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11 pages, 1574 KiB

Open AccessCommunication

Efficacy of Soft-Rot Disease Biocontrol Agents in the Inhibition of Production Field Pathogen Isolates

by Jérémy Cigna, Kévin Robic, Pauline Dewaegeneire, Valérie Hélias, Amélie Beury and Denis Faure

Microorganisms 2023, 11(2), 372; https://doi.org/10.3390/microorganisms11020372 - 1 Feb 2023

Cited by 4 | Viewed by 1532

Abstract

The Dickeya and Pectobacterium bacterial species cause blackleg and soft-rot diseases on potato plants and tubers. Prophylactic actions are essential to conserve a high quality of seed potato tubers. Biocontrol approaches are emerging, but we need to know how efficient biocontrol agents are [...] Read more.

The Dickeya and Pectobacterium bacterial species cause blackleg and soft-rot diseases on potato plants and tubers. Prophylactic actions are essential to conserve a high quality of seed potato tubers. Biocontrol approaches are emerging, but we need to know how efficient biocontrol agents are when facing the natural diversity of pathogens. In this work, we sampled 16 production fields, which were excluded from the seed tuber certification scheme, as well as seven experimental parcels, which were planted with seed tubers from those production fields. We collected and characterized 669 Dickeya and Pectobacterium isolates, all characterized using nucleotide sequence of the gapA gene. This deep sampling effort highlighted eleven Dickeya and Pectobacterium species, including four dominant species namely D. solani, D. dianthicola, P. atrosepticum and P. parmentieri. Variations in the relative abundance of pathogens revealed different diversity patterns at a field or parcel level. The Dickeya-enriched patterns were maintained in parcels planted with rejected seed tubers, suggesting a vertical transmission of the pathogen consortium. Then, we retained 41 isolates representing the observed species diversity of pathogens and we tested each of them against six biocontrol agents. From this work, we confirmed the importance of prophylactic actions to discard contaminated seed tubers. We also identified a couple of biocontrol agents of the Pseudomonas genus that were efficient against a wide range of pathogen species. Full article

(This article belongs to the Special Issue Dickeya and Pectobacterium: Ecology, Pathology and Plant Protection 2.0)

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16 pages, 3491 KiB

Open AccessArticle

Diversity of Bacterial Soft Rot-Causing Pectobacterium Species Affecting Cabbage in Serbia

by Aleksandra Jelušić, Petar Mitrović, Sanja Marković, Renata Iličić, Predrag Milovanović, Slaviša Stanković and Tatjana Popović Milovanović

Microorganisms 2023, 11(2), 335; https://doi.org/10.3390/microorganisms11020335 - 29 Jan 2023

Cited by 4 | Viewed by 2846

Abstract

The aim of this work was to identify and characterize the pectolytic bacteria responsible for the emergence of bacterial soft rot on two summer cabbage hybrids (Cheers F1 and Hippo F1) grown in the Futog locality (Bačka, Vojvodina), known for the five-century-long tradition [...] Read more.

The aim of this work was to identify and characterize the pectolytic bacteria responsible for the emergence of bacterial soft rot on two summer cabbage hybrids (Cheers F1 and Hippo F1) grown in the Futog locality (Bačka, Vojvodina), known for the five-century-long tradition of cabbage cultivation in Serbia. Symptoms manifesting as soft lesions on outer head leaves were observed during August 2021, while the inner tissues were macerated, featuring cream to black discoloration. As the affected tissue decomposed, it exuded a specific odor. Disease incidence ranged from 15% to 25%. A total of 67 isolates producing pits on crystal violet pectate (CVP) medium were characterized for their phenotypic and genotypic features. The pathogenicity was confirmed on cabbage heads. Findings yielded by the repetitive element palindromic-polymerase chain reaction (rep-PCR) technique confirmed interspecies diversity between cabbage isolates, as well as intraspecies genetic diversity within the P. carotovorum group of isolates. Based on multilocus sequence typing (MLST) using genes dnaX, mdh, icdA, and proA, five representative isolates were identified as Pectobacterium carotovorum (Cheers F1 and Hippo F1), while two were identified as Pectobacterium versatile (Hippo F1) and Pectobacterium odoriferum (Hippo F1), respectively, indicating the presence of diverse Pectobacterium species even in combined infection in the same field. Among the obtained isolates, P. carotovorum was the most prevalent species (62.69%), while P. versatile and P. odoriferum were less represented (contributing by 19.40% and 17.91%, respectively). Multilocus sequence analysis (MLSA) performed with concatenated sequences of four housekeeping genes (proA, dnaX, icdA, and mdh) and constructed a neighbor-joining phylogenetic tree enabled insight into the phylogenetic position of the Serbian cabbage Pectobacterium isolates. Bacterium P. odoriferum was found to be the most virulent species for cabbage, followed by P. versatile, while all three species had comparable virulence with respect to potato. The results obtained in this work provide a better understanding of the spreading routes and abundance of different Pectobacterium spp. in Serbia. Full article

(This article belongs to the Special Issue Dickeya and Pectobacterium: Ecology, Pathology and Plant Protection 2.0)

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17 pages, 3365 KiB

Open AccessArticle

Disalicylic Acid Provides Effective Control of Pectobacterium brasiliense

by Sapir Tuizer, Manoj Pun, Iris Yedidia and Zohar Kerem

Microorganisms 2022, 10(12), 2516; https://doi.org/10.3390/microorganisms10122516 - 19 Dec 2022

Viewed by 1871

Abstract

Bis(2-carboxyphenyl) succinate (disalicylic acid; DSA) is composed of two salicylic acids connected by a succinyl linker. Here, we propose its use as a new, synthetic plant-protection agent. DSA was shown to control Pectobacterium brasiliense, an emerging soft-rot pathogen of potato and ornamental [...] Read more.

Bis(2-carboxyphenyl) succinate (disalicylic acid; DSA) is composed of two salicylic acids connected by a succinyl linker. Here, we propose its use as a new, synthetic plant-protection agent. DSA was shown to control Pectobacterium brasiliense, an emerging soft-rot pathogen of potato and ornamental crops, at minimal inhibitory concentrations (MIC) lower than those of salicylic acid. Our computational-docking analysis predicted that DSA would inhibit the quorum-sensing (QS) synthase of P. brasiliense ExpI more strongly than SA would. In fact, applying DSA to P. brasiliense inhibited its biofilm formation, secretion of plant cell wall-degrading enzymes, motility and production of acyl–homoserine lactones (AHL) and, subsequently, impaired its virulence. DSA also inhibited the production of AHL by a QS-negative Escherichia coli strain (DH5α) that had been transformed with P. brasiliense AHL synthase, as demonstrated by the biosensors Chromobacterium violaceaum CV026 and E. coli pSB401. Inhibition of the QS machinery appears to be one of the mechanisms by which DSA inhibits specific virulence determinants. A new route is proposed for the synthesis of DSA, which holds greater potential for use as an anti-virulence agent than its precursor SA. Based on these findings, DSA is an excellent candidate for repurposing for new applications. Full article

(This article belongs to the Special Issue Dickeya and Pectobacterium: Ecology, Pathology and Plant Protection 2.0)

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17 pages, 1520 KiB

Open AccessArticle

Natural Infections of Potato Plants Grown from Minitubers with Blackleg-Causing Soft Rot Pectobacteriaceae

by Jan van der Wolf, Marjon Krijger, Odette Mendes, Viola Kurm and Jack Gros

Microorganisms 2022, 10(12), 2504; https://doi.org/10.3390/microorganisms10122504 - 17 Dec 2022

Cited by 4 | Viewed by 2385

Abstract

Information on the infection incidence of blackleg-causing soft rot Pectobacteriaceae (BL-SRP) in potato crops grown from minitubers (PB1-crop) and the distribution of BL-SRP in individual plants was collected during a two-year survey conducted at five potato growers located in the Netherlands. In the [...] Read more.

Information on the infection incidence of blackleg-causing soft rot Pectobacteriaceae (BL-SRP) in potato crops grown from minitubers (PB1-crop) and the distribution of BL-SRP in individual plants was collected during a two-year survey conducted at five potato growers located in the Netherlands. In the last weeks before haulm destruction, leaves, stems, and tubers of 100 or 200 plants were analyzed separately for the presence of Pectobacterium parmentieri, P. brasiliense, P. atrosepticum, and Dickeya spp. Extracted plant parts enriched for BL-SRP were analyzed with TaqMan assays specific for the detection of blackleg-causing BL-SRP. In 2019, low incidences of P. parmentieri (1–6%) in leaves were found at four growing sites. At one farm, reactions were detected in TaqMan assays for D. zeae and D. chrysanthemi in leaves. In 2020, the crops of two growers were largely free from BL-SRP. At one farm, a high infection incidence (21%) was found for D. fangzhongdai in tubers. The isolated pathogen was able to cause potato blackleg. At two other farms, high infection incidences in tubers were found with P. brasiliense (35–39%) and P. parmentieri (12–19%), whereas the incidence of P. brasiliense in leaves was also high (8%). In conclusion, high infection incidences with BL-SRP in potatoes can be found in a PB1 crop at the end of the growing season. Infections in individual plants were found either in tubers or in leaves. The potential sources of initial infection are discussed. Full article

(This article belongs to the Special Issue Dickeya and Pectobacterium: Ecology, Pathology and Plant Protection 2.0)

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12 pages, 26644 KiB

Open AccessArticle

Patterns of Genomic Variations in the Plant Pathogen Dickeya solani

by Slimane Khayi, Kok-Gan Chan and Denis Faure

Microorganisms 2022, 10(11), 2254; https://doi.org/10.3390/microorganisms10112254 - 14 Nov 2022

Cited by 2 | Viewed by 1962

Abstract

The plant pathogen Dickeya solani causes soft rot and blackleg diseases in several crops including Solanum tuberosum. Unveiling the patterns of its diversity contributes to understanding the emergence and virulence of this pathogen in potato agro-systems. In this study, we analyzed the [...] Read more.

The plant pathogen Dickeya solani causes soft rot and blackleg diseases in several crops including Solanum tuberosum. Unveiling the patterns of its diversity contributes to understanding the emergence and virulence of this pathogen in potato agro-systems. In this study, we analyzed the genome of several D. solani strains exhibiting an atypically high number of genetic variations. Variant calling and phylogenomics support the evidence that the strains RNS10-105-1A, A623S-20A-17 and RNS05.1.2A belong to a divergent sub-group of D. solani for which we proposed RNS05.1.2A as a reference strain. In addition, we showed that the variations (1253 to 1278 snp/indels) in strains RNS13-30-1A, RNS13-31-1A and RNS13-48-1A were caused by a horizontal gene transfer event from a donor belonging to the D. solani RNS05.1.2A subgroup. The overall results highlight the patterns driving the diversification in D. solani species. This work contributes to understanding patterns and causes of diversity in the emerging pathogen D. solani. Full article

(This article belongs to the Special Issue Dickeya and Pectobacterium: Ecology, Pathology and Plant Protection 2.0)

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13 pages, 2659 KiB

Open AccessArticle

Hfq Is a Critical Modulator of Pathogenicity of Dickeya oryzae in Rice Seeds and Potato Tubers

by Zurong Shi, Qingwei Wang, Shunchang Wang, Chengrun Wang, Lian-Hui Zhang and Zhibin Liang

Microorganisms 2022, 10(5), 1031; https://doi.org/10.3390/microorganisms10051031 - 16 May 2022

Cited by 3 | Viewed by 2268

Abstract

The frequent outbreaks of soft-rot diseases caused by Dickeya oryzae have emerged as severe problems in plant production in recent years and urgently require the elucidation of the virulence mechanisms of D. oryzae. Here, we report that Hfq, a conserved RNA chaperone [...] Read more.

The frequent outbreaks of soft-rot diseases caused by Dickeya oryzae have emerged as severe problems in plant production in recent years and urgently require the elucidation of the virulence mechanisms of D. oryzae. Here, we report that Hfq, a conserved RNA chaperone protein in bacteria, is involved in modulating a series of virulence-related traits and bacterial virulence in D. oryzae EC1. The findings show that the null mutation of the hfq_EC1 gene totally abolished the production of zeamine phytotoxins and protease, significantly attenuated the production of two other types of cell wall degrading enzymes, i.e., pectate lyase and cellulase, as well as attenuating swarming motility, biofilm formation, the development of hypersensitive response to Nicotiana benthamiana, and bacterial infections in rice seeds and potato tubers. QRT-PCR analysis and promoter reporter assay further indicated that Hfq_EC1 regulates zeamine production via modulating the expression of the key zeamine biosynthesis (zms) cluster genes. Taken together, these findings highlight that the Hfq of D. oryzae is one of the key regulators in modulating the production of virulence determinants and bacterial virulence in rice seeds and potato tubers. Full article

(This article belongs to the Special Issue Dickeya and Pectobacterium: Ecology, Pathology and Plant Protection 2.0)

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15 pages, 24035 KiB

Open AccessArticle

Unraveling the Uncharacterized Domain of Carocin S2: A Ribonuclease Pectobacterium carotovorum subsp. carotovorum Bacteriocin

by Ping-Chen Chung, Ruchi Briam James S. Lagitnay, Reymund C. Derilo, Jian-Li Wu, Yutin Chuang, Jia-De Lin and Duen-Yau Chuang

Microorganisms 2022, 10(2), 359; https://doi.org/10.3390/microorganisms10020359 - 4 Feb 2022

Cited by 1 | Viewed by 2682

Abstract

Carocin S2 is a bacteriocin with a low molecular weight generated by Pectobacterium carotovorum subsp. carotovorum 3F3 strain. The caroS2K gene, which is found in the genomic DNA alongside the caroS2I gene, which codes for an immunity protein, encodes this bacteriocin. We explored [...] Read more.

Carocin S2 is a bacteriocin with a low molecular weight generated by Pectobacterium carotovorum subsp. carotovorum 3F3 strain. The caroS2K gene, which is found in the genomic DNA alongside the caroS2I gene, which codes for an immunity protein, encodes this bacteriocin. We explored the residues responsible for Carocin S2’s cytotoxic or RNA-se activity using a structure-based mutagenesis approach. The minimal antibiotic functional region starts at Lys691 and ends at Arg783, according to mutational research. Two residues in the identified region, Phe760 and Ser762, however, are unable to demonstrate this activity, suggesting that these sites may interact with another domain. Small modifications in the secondary structure of mutant caroS2K were revealed by circular dichroism (CD) spectroscopy and intrinsic tryptophan fluorescence (ITF), showing ribosomal RNA cleavage in the active site. A co-immunoprecipitation test indicated that the immunity protein CaroS2I binds to CaroS2K’s C-terminus, while a region under the uncharacterized Domain III inhibits association of N-terminally truncated CaroS2K from interacting with CaroS2I. Carocin S2, a ribosomal ribonuclease bacteriocin, is the first to be identified with a domain III that encodes the cytotoxic residues as well as the binding sites between its immunity and killer proteins. Full article

(This article belongs to the Special Issue Dickeya and Pectobacterium: Ecology, Pathology and Plant Protection 2.0)

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