scholarly journals Identification and Characterization of the Bacteriocin Carocin S3 from the Multiple Bacteriocin Producing Strain of Pectobacterium carotovorum subsp. carotovorum

2020 ◽  
Author(s):  
Jyun-Wei Wang ◽  
Reymund Callanga Derilo ◽  
Ruchi Briam James Lagitnay ◽  
Huang-Pin Wu ◽  
Kai-In Chen ◽  
...  
Keyword(s):  
Soft Rot ◽  
Nuclease Activity ◽  
Antimicrobial Activities ◽  
Indicator Strain ◽  
Open Reading Frames ◽  
Economic Losses ◽  
Pectobacterium Carotovorum ◽  
Chromosomal Dna ◽  
High Concentration ◽  
Killer Protein

Abstract Background: Pectobacterium carotovorum subsp. carotovorum belongs to the Enterobacteriaceae family, which causes soft-rot disease in numerous plants worldwide resulting in significant economic losses. Results from our previous studies showed that the strain H-rif-8-6 produces low-molecular-weight bacteriocin (LMWB) Carocin S1. Interestingly, TH22-10, the caroS1K:Tn5 insertional mutant in H-rif-8-6, loses Carocin S1 producing ability, but still produces other LMWBs which the indicator strain SP33 can detect. The SP33 is one of the many strains that are sensitive toward the cytotoxic effects of Carocin S3K, but not Carocin S1. The result revealed that H-rif-8-6 is a multiple-bacteriocin producing strain.Results: In this study, a 4.1-kb DNA fragment was isolated from the chromosomal DNA of Pcc strain, H-rif-8-6, by a DNA probe using the caroS1K gene as the template. DNA sequencing and analysis by GenBank revealed two complete open reading frames (ORFs), designated ORF1 and ORF2, which were identified within the sequence fragment. ORF1 and ORF2, similar to the identified carocin S2 genes, encode the killer (Carocin S3K) and the immunity (Carocin S3I) proteins, respectively, which were homologous to the colicin E3 gene. Carocin S3K and Carocin S3I were expressed, isolated, and purified in Escherichia coli BL21 after subcloning of the expression plasmid pGS3KI or pGSK3I. SDS-PAGE analysis showed that the relative masses of Carocin S3K and Carocin S3I were 95.6 kDa and 10.2 kDa, respectively. The results reveal that Carocin S3K has higher antimicrobial and specific antimicrobial activities for Pcc along with a nuclease activity than Carocin S3I. However, Carocin S3I inhibits the activity of Carocin S3K. Interestingly, a high concentration of Carocin S3I protein is also a DNA nuclease, and Carocin S3K also inhibits its activity.Conclusion: This study showed that another type of bacteriocin was found in Pectobacterium carotovorum. This new type of bacteriocin, Carocin S3, has the killer protein, Carocin S3K, and the immunity protein, Carocin S3I.

scholarly journals Identification and Characterization of the Bacteriocin Carocin S3 from the Multiple Bacteriocin Producing Strain of Pectobacterium carotovorum subsp. carotovorum

2020 ◽  
Author(s):  
Jyun-Wei Wang ◽  
Reymund Callanga Derilo ◽  
Ruchi Briam James Lagitnay ◽  
Huang-Pin Wu ◽  
Kai-In Chen ◽  
...  
Keyword(s):  
Soft Rot ◽  
Nuclease Activity ◽  
Antimicrobial Activities ◽  
Indicator Strain ◽  
Open Reading Frames ◽  
Economic Losses ◽  
Pectobacterium Carotovorum ◽  
Chromosomal Dna ◽  
High Concentration ◽  
Killer Protein

Abstract Background: Pectobacterium carotovorum subsp. carotovorum belongs to the Enterobacteriaceae family, which causes soft-rot disease in numerous plants worldwide resulting in significant economic losses. Results from our previous studies showed that the strain H-rif-8-6 produces low-molecular-weight bacteriocin (LMWB) Carocin S1. Interestingly, TH22-10, the caroS1K:Tn5 insertional mutant in H-rif-8-6, loses Carocin S1 producing ability, but still produces other LMWBs which the indicator strain SP33 can detect. The SP33 is one of the many strains that are sensitive toward the cytotoxic effects of Carocin S3K, but not Carocin S1. The result revealed that H-rif-8-6 is a multiple-bacteriocin producing strain.Results: In this study, a 4.1-kb DNA fragment was isolated from the chromosomal DNA of Pcc strain, H-rif-8-6, by a DNA probe using the caroS1K gene as the template. DNA sequencing and analysis by GenBank revealed two complete open reading frames (ORFs), designated ORF1 and ORF2, which were identified within the sequence fragment. ORF1 and ORF2, similar to the identified carocin S2 genes, encode the killer (Carocin S3K) and the immunity (Carocin S3I) proteins, respectively, which were homologous to the colicin E3 gene. Carocin S3K and Carocin S3I were expressed, isolated, and purified in Escherichia coli BL21 after subcloning of the expression plasmid pGS3KI or pGSK3I. SDS-PAGE analysis showed that the relative masses of Carocin S3K and Carocin S3I were 95.6 kDa and 10.2 kDa, respectively. The results reveal that Carocin S3K has higher antimicrobial and specific antimicrobial activities for Pcc along with a nuclease activity than Carocin S3I. However, Carocin S3I inhibits the activity of Carocin S3K. Interestingly, a high concentration of Carocin S3I protein is also a DNA nuclease, and Carocin S3K also inhibits its activity.Conclusion: This study showed that another type of bacteriocin was found in Pectobacterium carotovorum. This new type of bacteriocin, Carocin S3, has the killer protein, Carocin S3K, and the immunity protein, Carocin S3I.

scholarly journals Identification and Characterization of the Bacteriocin Carocin S3 from the Multiple Bacteriocin Producing Strain of Pectobacterium Carotovorum Subsp. Carotovorum

2020 ◽  
Author(s):  
REYMUND CALLANGA DERILO ◽  
Jyun-Wei Wang ◽  
Ruchi Briam James Lagitnay ◽  
Huang-Pin Wu ◽  
Kai-In Chen ◽  
...  
Keyword(s):  
Soft Rot ◽  
Nuclease Activity ◽  
Antimicrobial Activities ◽  
Indicator Strain ◽  
Open Reading Frames ◽  
Economic Losses ◽  
Pectobacterium Carotovorum ◽  
High Concentration ◽  
The Many ◽  
Killer Protein

Abstract BackgroundPectobacterium carotovorum subsp. carotovorum belongs to the Enterobacteriaceae family which causes soft rot disease in numerous plants worldwide resulting in significant economic losses. Results from our previous studies showed that the strain H-rif-8-6 produces low-molecular-weight bacteriocin (LMWB) Carocin S1. Interestingly, TH22-10, the caroS1K:Tn5 insertional mutant in H-rif-8-6, loses Carocin S1 producing ability, but still produces other LMWBs which can be detected by using the indicator strain SP33. The SP33 is one of the many strains that are sensitive toward the cytotoxic effects of CaroS3K, but not Carocin S1. The result revealed that H-rif-8-6 is a multiple-bacteriocin producing strain.ResultsIn this study, a 4.1-kb DNA fragment was isolated by a DNA probe using the caroS1K gene as the template. DNA sequencing and analysis by GenBank revealed two complete open reading frames (ORFs), designated ORF1 and ORF2, which were identified within the sequence fragment. ORF1 and ORF2, similar to the identified Carocin S2 genes, encode the killer (CaroS3K) and the immunity (CaroS3I) proteins, respectively, which were homologous to the colicin E3 gene. CaroS3K and CaroS3I were expressed, isolated, and purified in Escherichia coli BL21 after subcloning of the expression plasmid pGS3KI or pGSK3I. SDS-PAGE analysis showed that the relative masses of CaroS3K and CaroS3I were 95 kDa and 10 kDa, respectively. The results reveal that CaroS3K has higher antimicrobial and specific antimicrobial activities for Pcc along with a nuclease activity than CaroS3I. However, CaroS3I inhibits the activity of CaroS3K. Interestingly, high concentration of CaroS3I protein is also a DNA nuclease, and its activity is also inhibited by CaroS3K.ConclusionThis study showed that another type of bacteriocin was found in Pectobacterium carotovorum. This new type of bacteriocin, Carocin S3, has the killer protein, CaroS3K, and the immunity protein, CaroS3I.

scholarly journals Identification and Characterization of the Bacteriocin Carocin S3 from the Multiple Bacteriocin Producing Strain of Pectobacterium carotovorum subsp. carotovorum

2020 ◽  
Author(s):  
Jyun-Wei Wang ◽  
Reymund Callanga Derilo ◽  
Ruchi Briam James Lagitnay ◽  
Huang-Pin Wu ◽  
Kai-In Chen ◽  
...  
Keyword(s):  
Soft Rot ◽  
Nuclease Activity ◽  
Antimicrobial Activities ◽  
Indicator Strain ◽  
Open Reading Frames ◽  
Pectobacterium Carotovorum ◽  
Chromosomal Dna ◽  
High Concentration ◽  
Carotovorum Subsp ◽  
Killer Protein

Abstract Background: Pectobacterium carotovorum subsp. carotovorum belongs to the Enterobacteriaceae family which causes soft-rot disease in numerous plants worldwide resulting in significant economic losses.Results from our previous studies showed that the strain H-rif-8-6 produces low-molecular-weight bacteriocin (LMWB) Carocin S1. Interestingly, TH22-10, the caroS1K:Tn5 insertional mutant in H-rif-8-6, loses Carocin S1 producing ability, but still produces other LMWBs which can be detected by using the indicator strain SP33. The SP33 is one of the many strains that are sensitive toward the cytotoxic effects of Carocin S3K, but not Carocin S1. The result revealed that H-rif-8-6 is a multiple-bacteriocin producing strain. Results: In this study, a 4.1-kb DNA fragment was isolated from the chromosomal DNA of Pcc strain, H-rif-8-6, by a DNA probe using the caroS1K gene as the template. DNA sequencing and analysis by GenBank revealed two complete open reading frames (ORFs), designated ORF1 and ORF2, which were identified within the sequence fragment. ORF1 and ORF2, similar to the identified Carocin S2 genes, encode the killer (Carocin S3K) and the immunity (Carocin S3I) proteins, respectively, which were homologous to the colicin E3 gene. Carocin S3K and Carocin S3I were expressed, isolated, and purified in Escherichia coli BL21 after subcloning of the expression plasmid pGS3KI or pGSK3I. SDS-PAGE analysis showed that the relative masses of Carocin S3K and Carocin S3I were 95.6 kDa and 10.2 kDa, respectively. The results reveal that Carocin S3K has higher antimicrobial and specific antimicrobial activities for Pcc along with a nuclease activity than Carocin S3I. However, Carocin S3I inhibits the activity of Carocin S3K. Interestingly, high concentration of Carocin S3I protein is also a DNA nuclease, and its activity is also inhibited by Carocin S3K.Conclusion: This study showed that another type of bacteriocin was found in Pectobacterium carotovorum. This new type of bacteriocin, Carocin S3, has the killer protein, Carocin S3K, and the immunity protein, Carocin S3I.

scholarly journals Injectisome T3SS Subunits As Potential Chaperones In The Extracellular Export of Pectobacterium Carotovorum Subsp. Carotovorum Bacteriocins Carocin S1 And Carocin S3 Secreted Via Flagellar T3SS

2021 ◽  
Author(s):  
Hang-Cheng Chen ◽  
Reymund C. Derilo ◽  
Han-Ling Chen ◽  
Tzu-Rung Li ◽  
Ruchi Briam James S. Lagitnay ◽  
...  
Keyword(s):  
Type Iii Secretion ◽  
Insertional Mutagenesis ◽  
Plant Pathogens ◽  
Soft Rot ◽  
Economic Losses ◽  
Pectobacterium Carotovorum ◽  
Secretion Systems ◽  
Unique Type ◽  
Bacterial Flagellum ◽  
Type Iii

Abstract Pectobacterium carotovorum subsp. carotovorum (Pcc) causes soft-rot disease in a wide variety of plants resulting in economic losses worldwide. It produces various types of bacteriocin to compete against related plant pathogens. Studies on how bacteriocins are extracellularly secreted are conducted to understand the mechanism of interbacterial competition. In this study, the secretion of the low-molecular-weight bacteriocins (LMWB) Carocin S1 and Carocin S3 produced by a multiple-bacteriocin producing strain of Pcc, 89-H-4, was investigated. Tn5 insertional mutagenesis was used to generate a mutant, TH22-6, incapable of LMWBs secretion. Sequence and homology analyses of the gene disrupted by transposon Tn5 insertion revealed that the gene sctT, an essential component of the injectisome type III secretion machinery (T3aSS), is required for the secretion of the bacteriocins. This result raised a question regarding the nature of the secretion mechanism of Pcc bacteriocins which was previously discovered to be secreted via T3bSS, a system that utilizes the bacterial flagellum for extracellular secretions. Our previous report has shown that bacteriocin Carocin S1 cannot be secreted by mutants that are defective of T3bSS-related genes such as flhA, flhC, flhD and fliC. We knocked out several genes making up the significant structural components of both T3aSS and T3bSS. The findings led us to hypothesize the potential roles of the T3aSS-related proteins, SctT, SctU and SctV, as flagellar T3SS chaperones in the secretion of Pcc bacteriocins. This current discovery and the findings of our previous study helped us to conceptualize a unique Type III secretion system for bacteriocin extracellular export which is a hybrid of the injectisome and flagellar secretion systems.

scholarly journals Emergence of Bacterial Soft Rot in Cucumber Caused by Pectobacterium carotovorum subsp. brasiliense in China

Plant Disease ◽  
2017 ◽  
Vol 101 (2) ◽  
pp. 279-287 ◽  
Author(s):  
Xianglong Meng ◽  
Ali Chai ◽  
Yanxia Shi ◽  
Xuewen Xie ◽  
Zhanhong Ma ◽  
...  
Keyword(s):  
Sequence Analysis ◽  
Soft Rot ◽  
Economic Losses ◽  
Pectobacterium Carotovorum ◽  
Bacterial Soft Rot ◽  
Bacterial Strains ◽  
Phenotypic Properties ◽  
Gene Sequence Analysis ◽  
Wide Range ◽  
Carotovorum Subsp

During 2014 to 2015, a devastating bacterial soft rot on cucumber stems and leaves occurred in Shandong, Shanxi, Hebei, Henan, and Liaoning provinces of China, resulting in serious economic losses for cucumber production. The gummosis emerged on the surface of leaves, stems, petioles, and fruit of cucumber. The basal stem color was dark brown and the stem base turned to wet rot. Yellow spots and wet rot emerged at the edge of the infected cucumber leaves and gradually infected the leaf centers. In total, 45 bacterial strains were isolated from the infected tissues. On the basis of phenotypic properties of morphology, physiology, biochemistry, and 16S ribosomal RNA gene sequence analysis, the pathogen was identified as Pectobacterium carotovorum. Multilocus sequence analysis confirmed that the isolates were P. carotovorum subsp. brasiliense, and the pathogens fell in clade II. The pathogenicity of isolated bacteria strains was confirmed. The strains reisolated were the same as the original. The host range test confirmed that strains had a wide range of hosts. As far as we know, this is the first report of cucumber stem soft rot caused by P. carotovorum subsp. brasiliense in China as well as in the world, which has a significant economic impact on cucumber production.

scholarly journals Characterization of a New Bacteriocin, Carocin D, from Pectobacterium carotovorum subsp. carotovorum Pcc21

2010 ◽  
Vol 76 (22) ◽  
pp. 7541-7549 ◽  
Author(s):  
Eunjung Roh ◽  
Tae-Ho Park ◽  
Myung-il Kim ◽  
Seungdon Lee ◽  
Sangryeol Ryu ◽  
...  
Keyword(s):  
Amino Acids ◽  
Antibacterial Activity ◽  
Biological Control Agent ◽  
Soft Rot ◽  
Control Agent ◽  
Indicator Strain ◽  
Amino Acid Sequences ◽  
Pectobacterium Carotovorum ◽  
N Terminus

ABSTRACT Two different bacteriocins, carotovoricin and carocin S1, had been found in Pectobacterium carotovorum subsp. carotovorum, which causes soft-rot disease in diverse plants. Previously, we reported that the particular strain Pcc21, producing only one high-molecular-weight bacteriocin, carried a new antibacterial activity against the indicator strain Pcc3. Here, we report that this new antibacterial activity is due to a new bacteriocin produced by strain Pcc21 and named carocin D. Carocin D is encoded by the caroDK gene located in the genomic DNA together with the caroDI gene, which seems to encode an immunity protein. N-terminal amino acid sequences of purified carocin D were determined by Edman degradation. In comparison with the primary translation product of caroDK, it was found that 8 amino acids are missing at the N terminus. This finding proved that carocin D is synthesized as a precursor peptide and that 8 amino acids are removed from its N terminus during maturation. Carocin D has two putative translocation domains; the N-terminal and C-terminal domains are homologous to those of Escherichia coli colicin E3 and Pseudomonas aeruginosa S-type pyocin, respectively. When caroDK and caroDI genes were transformed into carocin D-sensitive bacteria such as Pcc3, the bacteria became resistant to this bacteriocin. Carocin D has one putative DNase domain at the extreme C terminus and showed DNase activity in vitro. This bacteriocin had slight tolerance to heat but not to proteases. The caroDK gene was present in only 5 of 54 strains of P. carotovorum subsp. carotovorum. These results indicate that carocin D is a third bacteriocin found in P. carotovorum subsp. carotovorum, and this bacteriocin can be readily expressed in carocin D-sensitive nonpathogenic bacteria, which may have high potential as a biological control agent in the field.

scholarly journals First Report of Soft Rot Caused by Pectobacterium carotovorum subsp. carotovorum on Pepper Fruits (Capsicum annuum) in Malaysia

Plant Disease ◽  
2013 ◽  
Vol 97 (8) ◽  
pp. 1109-1109 ◽  
Author(s):  
E. Golkhandan ◽  
S. Kamaruzaman ◽  
M. Sariah ◽  
M. Z. Zainal Abidin ◽  
A. Nasehi ◽  
...  
Keyword(s):  
16S Rrna ◽  
Capsicum Annuum ◽  
Soft Rot ◽  
Rrna Genes ◽  
Economic Losses ◽  
Pectobacterium Carotovorum ◽  
Bacterial Strains ◽  
Appl Environ ◽  
Pathogenicity Tests ◽  
Carotovorum Subsp

Symptoms of water-soaked lesions and soft rot were first observed in June 2011 on bell pepper fruits (Capsicum annuum cv. Annuum) in the two main regions of pepper production in Malaysia (Cameron Highlands and Johor State). Economic losses exceeded 40% in severely infected fields and greenhouses with the estimated disease incidence of 70%. In pepper fruits damaged by insects, sunscald, or other factors, symptoms initially appeared in the peduncle and calyx tissues and entire fruits were turned into watery masses within 2 to 6 days. Fruits infected in the field tended to collapse and hang on the plant. When the contents leaked out, the outer skin of the fruit dried and remained attached to the plant. Field-grown transplants and infected soil were identified as probable sources of inocula. A total of 50 attached fruits were collected from 10 pepper fields and greenhouses located in the two growing regions. Tissue from the margins of water-soaked lesions was surface-sterilized in 1% NaOCl for 2 min, rinsed in sterile water, dried, and plated onto nutrient agar (NA) and eosin methylene blue agar (EMB) media (3). A similar bacterium was isolated from all samples. After 2 days, white to creamy bacterial colonies on NA and emerald green colonies on EMB developed. Five independent strains were subjected to further biochemical, molecular, and pathogenicity tests. Bacterial strains were gram-negative, motile rods, grew at 37°C, were facultatively anaerobic, oxidase-negative, phosphatase-negative, and catalase-positive. They degraded pectate, were sensitive to erythromycin, did not utilize Keto-methyl glucoside, were indole production-negative, and reduced sugars from sucrose (3). Acid production was negative from sorbitol and arabitol, but positive from melibiose and citrate. PCR amplification of the pel gene by Y1 and Y2 primers produced a 434-bp fragment (2). Amplification of the intergenic transcribed spacer (ITS) region by G1 and L1 primers (4) gave two amplicons ca. 550 and 580 bp long. The expected amplicon was not produced with any of the strains using primers Br1f/L1r and Eca1f/Eca2r (1), whereas a 550-bp PCR product, typical of Pectobacterium carotovorum subsp. carotovorum, was obtained with primers EXPCCF and EXPCCR (1). Based on biochemical and molecular characteristics, and analysis of PCR-RFLP of 16S-ITS-23R rRNA genes using Rsa I enzyme (4), all five bacterial strains were identified as P. carotovorum subsp. carotovorum. BLAST analysis of the 16S rRNA sequence (GenBank Accession No KC189032) showed 100% identity to the 16S rRNA of P. carotovorum subsp. carotovorum strain PPC192. For pathogenicity tests, four mature pepper fruits of cv. Annuum were inoculated by injecting 10 μl of a bacterial suspension (108 CFU/ml) into pericarps and the fruits were incubated in a moist chamber at 80 to 90% relative humidity and 30°C. After 72 h, water-soaked lesions similar to those observed in the fields and greenhouses were observed and bacteria with the same characteristics were consistently reisolated, thereby fulfilling Koch's postulates. Symptoms were not observed on water-inoculated controls. References: (1) S. Baghaee-Ravari et al. Eur. J. Plant Pathol. 129:413, 2001. (2) A. Darraas et al. Appl. Environ. Microbiol. 60:1437, 1994. (3) N. W Schaad et al. Laboratory Guide for the Identification of Plant Pathogenic Bacteria. 3rd ed. The American Phytopathological Society Press, St Paul, MN, 2001. (4) I. K. Toth et al. Appl. Environ. Microbiol. 67:4070, 2001.

scholarly journals Injectisome T3SS subunits as potential chaperones in the extracellular export of Pectobacterium carotovorum subsp. carotovorum bacteriocins Carocin S1 and Carocin S3 secreted via flagellar T3SS

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Huang-Pin Wu ◽  
Reymund C. Derilo ◽  
Han-Ling Chen ◽  
Tzu-Rung Li ◽  
Ruchi Briam James S. Lagitnay ◽  
...  
Keyword(s):  
Type Iii Secretion ◽  
Insertional Mutagenesis ◽  
Plant Pathogens ◽  
Soft Rot ◽  
Economic Losses ◽  
Pectobacterium Carotovorum ◽  
Secretion Systems ◽  
Unique Type ◽  
Bacterial Flagellum ◽  
Type Iii

AbstractPectobacterium carotovorum subsp. carotovorum (Pcc) causes soft-rot disease in a wide variety of plants resulting in economic losses worldwide. It produces various types of bacteriocin to compete against related plant pathogens. Studies on how bacteriocins are extracellularly secreted are conducted to understand the mechanism of interbacterial competition. In this study, the secretion of the low-molecular-weight bacteriocins (LMWB) Carocin S1 and Carocin S3 produced by a multiple-bacteriocin producing strain of Pcc, 89-H-4, was investigated. Tn5 insertional mutagenesis was used to generate a mutant, TH22–6, incapable of LMWBs secretion. Sequence and homology analyses of the gene disrupted by transposon Tn5 insertion revealed that the gene sctT, an essential component of the injectisome type III secretion machinery (T3aSS), is required for the secretion of the bacteriocins. This result raised a question regarding the nature of the secretion mechanism of Pcc bacteriocins which was previously discovered to be secreted via T3bSS, a system that utilizes the bacterial flagellum for extracellular secretions. Our previous report has shown that bacteriocin Carocin S1 cannot be secreted by mutants that are defective of T3bSS-related genes such as flhA, flhC, flhD and fliC. We knocked out several genes making up the significant structural components of both T3aSS and T3bSS. The findings led us to hypothesize the potential roles of the T3aSS-related proteins, SctT, SctU and SctV, as flagellar T3SS chaperones in the secretion of Pcc bacteriocins. This current discovery and the findings of our previous study helped us to conceptualize a unique Type III secretion system for bacteriocin extracellular export which is a hybrid of the injectisome and flagellar secretion systems.

scholarly journals Isolation and efficacy of two bacterial strains antagonists of Erwinia amylovora and Pectobacterium carotovorum

2021 ◽  
Vol 31 (1) ◽  
Author(s):  
M’hamed BENADA ◽  
Boualem BOUMAAZA ◽  
Sofiane BOUDALIA ◽  
Omar KHALADI
Keyword(s):  
Fire Blight ◽  
Erwinia Amylovora ◽  
Bacterial Species ◽  
Crop Protection ◽  
Soft Rot ◽  
Causal Agent ◽  
Plant Diseases ◽  
Ecological Niches ◽  
Pectobacterium Carotovorum ◽  
Bacterial Strains

Abstract Background The development of ecofriendly tools against plant diseases is an important issue in crop protection. Screening and selection process of bacterial strains antagonists of 2 pathogenic bacterial species that limit very important crops, Erwinia amylovora, the causal agent of the fire blight disease, and Pectobacterium carotovorum, the causal agent of bacterial potato soft rot, were reported. Bacterial colonies were isolated from different ecological niches, where both pathogens were found: rhizosphere of potato tubers and fruits and leaves of pear trees from the northwest region of Algeria. Direct and indirect confrontation tests against strains of E. amylovora and P. carotovorum were performed. Results Results showed a significant antagonistic activity against both phytopathogenic species, using direct confrontation method and supernatants of cultures (p<0.005). In vitro assays showed growth inhibitions of both phytopathogenic species. Furthermore, results revealed that the strains of S. plymuthica had a better inhibitory effect than the strains of P. fluorescens against both pathogens. In vivo results on immature pear fruits showed a significant decrease in the progression of the fire blight symptoms, with a variation in the infection index from one antagonistic strain to another between 31.3 and 50%, and slice of potato showed total inhibition of the pathogen (P. carotovorum) by the antagonistic strains of Serratia plymuthica (p<0.005). Conclusion This study highlighted that the effective bacteria did not show any infection signs towards plant tissue, and considered as a potential strategy to limit the fire blight and soft rot diseases.

scholarly journals Assessment of Xanthomonas arboricola pv. juglandis Bacterial Load in Infected Walnut Fruits by Quantitative PCR

Plant Disease ◽  
2019 ◽  
Vol 103 (10) ◽  
pp. 2577-2586
Author(s):  
Leonor Martins ◽  
Camila Fernandes ◽  
Pedro Albuquerque ◽  
Fernando Tavares
Keyword(s):  
Quantitative Pcr ◽  
Juglans Regia ◽  
Bacterial Load ◽  
Etiologic Agent ◽  
Economic Losses ◽  
Rapid Diagnostics ◽  
In Planta ◽  
Chromosomal Dna ◽  
Fruit Samples ◽  
Xanthomonas Arboricola

Xanthomonas arboricola pv. juglandis is the etiologic agent of important walnut (Juglans regia L.) diseases, causing severe fruit drop and high economic losses in walnut production regions. Rapid diagnostics and knowledge of bacterial virulence fitness are key to hinder disease progression and apply timely phytosanitary measures. This work describes an X. arboricola pv. juglandis-specific real-time quantitative PCR (qPCR) using X. arboricola pv. juglandis-specific DNA markers to quantify the bacterial load in infected walnut plant tissues. Method validation was achieved using calibration curves obtained with serial dilutions of X. arboricola pv. juglandis chromosomal DNA and standard curves obtained from walnut samples spiked with X. arboricola pv. juglandis cells. High correlations (R2 > 0.990 and > 0.995) and low limits of detection (35 chromosomes/qPCR reaction and 2.7 CFU/qPCR reaction) were obtained for both markers considering the calibration and standard curves, respectively. Assessment of qPCR repeatability, reproducibility, and specificity allowed us to demonstrate the reliability and consistency of the method. Furthermore, in planta quantification of X. arboricola pv. juglandis bacterial load using infected walnut fruit samples showed a higher detection resolution compared with standard PCR detection. By allowing quantification of virulence fitness of distinct X. arboricola pv. juglandis strains in planta, the proposed qPCR method may contribute to assertive risk assessment of walnut diseases caused by X. arboricola pv. juglandis and ultimately help to improve phytosanitary practices.

Sign in / Sign up

Export Citation Format

Share Document