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Two lactic acid bacteria (LAB) designated J02 and J13 were recovered from fermented vegetables based on their ability to suppress soft rot disease caused by Pectobacterium carotovorum subsp. carotovorum (Pcc) on radish. J02 and J13 were identified as Lactobacillus pentosus and Leuconostoc fallax, respectively. The ability of J02 and J13 to suppress plant diseases is highly dependent on chitosan. LAB alone has no effect and chitosan alone has only a moderate effect on disease reduction. However, J02 or J13 broth cultures plus chitosan display a strong inhibitory effect against plant pathogens and significantly reduces disease severity. LAB strains after being cultured in fish surimi (agricultural waste) and glycerol or sucrose-containing medium and mixed with chitosan, reduce three cruciferous vegetable diseases, including cabbage black spot caused by Alternaria brassicicola, black rot caused by Xanthomonas campestris pv. campestris, and soft rot caused by Pcc. Experimental trials reveal that multiple applications are more effective than a single application. In-vitro assays also reveal the J02/chitosan mixture is antagonistic against Colletotrichum higginsianum, Sclerotium rolfsii, and Fusarium oxysporum f. sp. rapae, indicating a broad-spectrum activity of LAB/chitosan. Overall, our results indicate that a synergistic combination of LAB and chitosan offers a promising approach to biocontrol.

Pectobacterium carotovorum, a causal agent of vegetable soft rot, contains three valid subspecies: P. carotovorum subsp. carotovorum (Pcc), P. carotovorum subsp. brasiliensis (Pcb), and P. carotovorum subsp. odoriferum (Pco). Using 16S rDNA sequencing and genus-specific PCR, we identified 72 P. carotovorum strains from Chinese cabbage, bok choy, and celery and assessed their pathogenicity on Chinese cabbage petioles and potato tubers. Based on phylogenetic analysis of pmrA sequences and confirmation by subspecies-specific PCR, the strains were divided into 18 Pcc, 29 Pco, and 25 Pcb. Several characteristic features were also assessed and supported the distinctiveness of the Pco strains. All P. carotovorum strains caused soft rot symptoms on Chinese cabbage and potato, but the Pco strains exhibited the greatest severity. We developed a conventional PCR and a quantitative PCR (qPCR) assay for the identification of Pco based on its specific srlE gene encoding sorbitol-specific phosphotransferase. These two methods could specifically amplify the expected products of 674 and 108 bp, respectively, from all of the Pco strains. The assays demonstrated high sensitivity and could detect as little as 1 and 100 pg/µl of bacterial genomic DNA, respectively. Both assays could also detect the pathogens directly from plant tissues infected with as little as 2.5 × 10−2 CFU/mg of Pco, even before external symptoms appeared. These assays constitute effective tools for disease diagnosis and the rapid identification of soft rot pathogens.

Soft rot, a major bacterial disease affecting the production of Chinese cabbage (Brassica rapa L. ssp. pekinensis) in China, has been widely attributed to Pectobacterium carotovorum subsp. carotovorum. Outbreaks of a new disease of Chinese cabbage caused considerable economic losses in many varieties from June to July of 2018 and 2019 in Harbin, China. This new disease had symptoms similar to those of soft rot but was different from bacterial rot caused by Pcc. Plants affected by this disease showed rot at the midrib of their leaves and stumps with short hyphae. A fungal strain named DBC755 was isolated from plant samples exhibiting soft rot to determine the relevant pathogen. The pathogen had a radial colonial morphology, white hyphae, and luxuriant branches in potato dextrose agar culture medium. The isolate was identified as Pythium ultimum var. ultimum on the basis of its morphology, biological characteristics, internal transcribed spacer, β-tubulin gene and coxII gene sequence analyses. A pure fungal culture was inoculated on Chinese cabbage, and rot symptoms were consistent with those observed in the field to satisfy Koch’s postulates. The discovery and biological characteristics of P. ultimum var. ultimum causing rot in Chinese cabbage provides a deeper understanding of soft rot and has great importance for the breeding of Chinese cabbage with resistance to this disease.

This study was aimed at identification and prevalence of potato soft rot and black leg disease agent in the potato production areas of Tokat province. In March-August 2018, 67 field surveys were carried out in Central, Turhal, Zile, Pazar, Erbaa, Niksar, Artova and Basciftlik districts of Tokat. The disease incidences were 0.25%, 0.33%, 0.31%, 0.5%, 1%, and 8% in Central, Erbaa, Niksar, Pazar, Turhal, and Zile district, respectively. In Artova and Basciftlik districts, no disease was encountered. The following tests, pectolytic activity on potato, gram reaction, catalase, oxidase, growth at 37°C and 39°C, salt tolerance, hypersensitivity reaction were applied to isolates obtained from diseased plant and tuber samples. In the PCR assay, 19 isolates were produced 434 bp product with Y1/Y2 primers specific to Pectobacterium spp., and 3 isolates were produced 420 bp product with ADE1/ADE2 primers specific to Dickeya spp. The isolates resulted positive with Y1/Y2 primers weren’t produced PCR product with ECA1/ECA2 primers specific to Pectobacterium atrosepticum. According to this, 19 isolates were identified as Pectobacterium carotovorum. With this study, the causal agent of potato blackleg and soft rot disease have been identified in the potato production areas of Tokat. Further studies will be conducted to determine the species and subspecies level of the pathogens using specific primers. Bu çalışma ile, Tokat ili patates üretim alanlarında patates karabacak ve yumuşak çürüklük hastalığının bulunma oranının belirlenmesi ve etmenin tanılanması amaçlanmıştır. 2018 yılı MartAğustos ayları arasında Tokat ili Merkez, Turhal, Zile, Pazar, Erbaa, Niksar, Artova ve Başçiftlik ilçelerinde patates üretiminin yoğun olarak yapıldığı alanlarda yapılan arazi surveylerinde 67 tarla incelenmiş olup, Tokat ilinde hastalığın Merkez’de %0,25, Erbaa ilçesinde %0,33, Niksar ilçesinde %0,31, Pazar ilçesinde %0,5, Turhal ilçesinde %1 ve Zile ilçesinde %8 oranında bulunduğu belirlenmiştir. Artova ve Başçiftlik ilçelerinde ise hastalığa rastlanılmamıştır. Toplanan hastalıklı bitki ve yumru örneklerinden elde edilen izolatlara, patateste pektolitik aktivite, gram reaksiyon, katalaz, oksidaz, 37°C ve 39°C sıcaklıklarda gelişim, tuza tolerans, tütünde aşırı duyarlılık testleri uygulanmıştır. Pectobacterium spp.’ye spesifik Y1/Y2 primerleri ile 19 izolat 434 bç PCR ürünü oluşturmuştur. 3 izolat Dickeya spp.’ye spesifik ADE1/ADE2 primerleri ile 420 bç PCR ürünü oluşturmuştur. Y1/Y2 primerlerine pozitif sonuç veren izolatlar ile Pectobacterium atrosepticum’a spesifik ECA1/ECA2 primerleri ile yapılan PCR çalışmasında ise izolatlar PCR ürünü oluşturmamıştır. Buna göre 19 izolat Pectobacterium carotovorum olarak sınıflandırılmıştır. Yapılan bu çalışma ile, Tokat ilinde patates üretim alanlarında patates karabacak ve yumuşak çürüklük hastalığına sebep olan etmenler belirlenmiş olup, ileriki çalışmalarda spesifik primerler ile tür ve alttür düzeyinde etmenlerin belirlenmesi planlanmaktadır.

A novel versatile glycoside hydrolase Cel5M was identified from Pectobacterium carotovorum and used in ramie degumming. The full-length Cel5M (GenBank: MH544226) containing the catalytic domain Cel5MD and its carbohydrate-binding module (CBM3) were expressed in E. coli. Both Cel5M and Cel5MD showed a broad substrate spectrum cleaving konjac glucomannan (KGM), carboxymethylcellulose (CMC) and oat spelt xylan. The optimal temperature of Cel5MD was 55oC with CMC and KGM, whereas the optimum temperature of Cel5M was 65oC with KGM and 60oC with CMC. The improved thermal activity with KGM was probably reflected also in the much lower K m with KGM than with CMC, indicating stronger binding of the full-length enzyme with KGM. Both enzymes were highly stable over a broad pH range from pH 5.0 to 9.0 with KGM. The use of the Cel5M enzyme together with the wild-type P. carotovorum HG-49 strain showed significant improvement when compared to using the mere strain HG-49 for application in ramie degumming. Moreover, the whole P. carotovorum Cel5M gene was over-expressed in P. carotovorum HG-49 itself to improve the ramie-degumming capacity. Altogether, this study indicates that in situ production of processing enzymes could be utilized in the textile industry.

The paper presents the results of studies to determine the optimal functioning parameters of aspartase and fumarase of the bacterial strain P. carotovorum MDC-8727, an aspartase producer. The temperature and pH optima of both enzymes are close and are in the range of T (35-40 °C) and pH (8.5-9.0). At a temperature of 50 °C, the thermal stability of aspartase is twice higher than that of fumarase. It was found that thermal treatment of cell biomass in the culture broth at low pH values contributed to the partial inactivation of fumarase. A similar treatment of cells at temperature of 50 °C and pH 5 for 90 minutes contributed to the complete inactivation of fumarase without harming the aspartase activity. fumarase, aspartase, L-aspartic acid, biotransformation

Phytochemical investigation led to the isolation of three alkaloids [skimmianine (1), vulcanine (2) and evoxine (3)] from the aerial parts of Haplophyllum tuberculatum, and two diacetylenic spiroketal enol ethers [spiroketalenolether polyyne (4) and [7-hexa-2,4-diynylidene-1,6-dioxaspiro[4.4]nona-2,8-dien-4-yl] acetate (5)] and a sesquiterpene lactone [8α acetoxy-11β,13dihydrokauniolide (6)] from the aerial parts of Chrysanthemum coronarium. The chemical structures of the isolated compounds were determined by using spectral data of 1H NMR, 13C NMR, as well as by comparison with literature data. Compounds 4, 1 and 5 were the most potent inhibitors against plant pathogenic bacteria Rhizobium radiobacter, Ralstonia solanacerum and Pectobacterium carotovorum ss. carotovorum with minimum inhibitory concentration (MIC) values of 31.3, 62.5 and 31.3 µg/ml, respectively. In antifungal assay, compounds 1 (MIC 62.5 µg/ml), 2 (MIC 62.5 µg/ml) and 5 (MIC 125 µg/ml) caused the highest inhibitory effects against phytopathogenic fungi Verticillium dahliae, Fusarium oxysporum and Alternaria solani, respectively. Moreover, crude extract of H. tuberculatum and 4 were significantly the most potent inhibitors of seed germination, root and shoot growth of Echinochloa crus-galli.

Magnetic cobalt Ferrite nanoparticles capped with caprylate groups, CH3(CH2)6CO2−, have been synthesized using a novel non-hydrolytic coprecipitation method under inert conditions. Particle diameter was characterized using dynamic light scattering (DLS) and transmission electron microscopy (TEM). The spinel ferrite crystal phase was verified using X-ray diffraction (XRD), and the presence of the capping agent was confirmed using Fourier Transform Infrared spectroscopy (FTIR). Bactericidal effects of the particles were tested against broth cultures of Erwinia carotovora and Stenotrophomonas maltophilia. The final particles had an average diameter of 3.81 nm and readily responded to a neodymium magnet. The particles did have a significant effect on the OD600 of both broth cultures.

Bacteria from Enterobacteriaceae family (SRE) are significant problem in plant production, not only during vegetation, in the field, but also during storage and marketing of agricultural commodities. Species P. carotovorum subsp. brasiliense (Pcb) is a newly identified member of Enterobacteriaceae family. It causes soft rot of different plant species, including root vegetables. Pcb is described as a new subspecies of P. carotovorum due to differences in phenotypic and genotypic characteristic, more pronounced virulence and aggressiveness. Patohogenicity of this bacterium is based on the production of several enzymes: pectatliase, polygalacturonase, cellulase and proeteases. The aim of this study was to determine whether and at which rate Pcb isolates originating from potato plants exhibit pectolytic activity on root of different root vegetable species - carrot, radish, celery, kohlrabi and beetroot. The obtained data confirmed wide host range of the bacterium Pectobacterium carotovorum subsp. brasiliense, but pointed to significant differences in pectolytic activity on different species of root vegetables (carrot, radish, celery, kohlrabi), while on beetroot tested Pcb isolates did not exhibit pectolytic activity. Moreover, on same species of root vegetables different levels of pectolytic activity of tested Pcb isolates were recorded.

AimThis work aimed at determining the pathogenicity, molecular characterization, host range and rapid detection of Pectobacterium carotovorum subsp. brasiliense (Pcb) causing soft rot disease in radish.Methods and ResultsThe four isolated isolates were inoculated to radish, typical soft rot symptoms were observed and Koch’s postulates were proved. The most virulent strain RDKLR was morphologically and biochemically distinct. Pcb showed a positive potato soft rot test and elicited hypersensitivity response on Nicotiana tobaccum. The genes Pel2 and pmrA were used for subspecies characterization of Pcb. It has a wide host range and infection was observed on slices of carrot, tomato, radish, potato, cauliflower, cabbage, chilli, knol-khol, bell pepper and cucumber. Infectivity was also seen in seedlings under glasshouse conditions. Pcb produced cell wall degrading enzymes in semi-quantification assay and is a strong biofilm producer. The LAMP technique was standardized to help rapid detection and take prophylactic measures to manage the disease.ConclusionThis work reports Pcb as a new soft rot causing organism of radish in India. Pcb is highly virulent with a broad host range. The LAMP technique helps in rapid detection.Significance and impact of the studyPcb-induced soft rot causes significant yield loss, decreased market value, damage in transit, storage and the market. Disease characterization and early identification aid in disease management and prevention in the field.

The present study aims to characterize and predict models for antibacterial activity of a novel oligosaccharide from

Irrigation with surface water carrying plant pathogens poses a risk for agriculture. Managed aquifer recharge enhances fresh water availability while simultaneously it may reduce the risk of plant diseases by removal of pathogens during aquifer passage. We compared the transport of three plant pathogenic bacteria with Escherichia coli WR1 as reference strain in saturated laboratory column experiments filled with quartz sand, or sandy aquifer sediments. E. coli showed the highest removal, followed by Pectobacterium carotovorum, Dickeya solani and Ralstonia solanacearum. Bacterial and non-reactive tracer breakthrough curves were fitted with Hydrus-1D and compared with colloid filtration theory (CFT). Bacterial attachment to fine and medium aquifer sand under anoxic conditions was highest with attachment rates of max. k att1 = 765 day -1 and 355 day -1, respectively. Attachment was the least to quartz sand under oxic conditions (k att1 = 61 day -1). In CFT, sticking efficiencies were higher in aquifer than in quartz sand but there was no differentiation between fine and medium aquifer sand. Overall removal ranged between < 6.8 log 10 m −1 in quartz and up to 40 log 10 m −1 in fine aquifer sand. Oxygenation of the anoxic aquifer sediments for two weeks with oxic influent water decreased the removal. The results highlight the potential of natural sand filtration to sufficiently remove plant pathogenic bacteria during aquifer storage.

Soft rot on potato tuber is a destructive disease caused by pathogenic bacterial species of the genera Pectobacterium and Dickeya. Accurate identification of the causal agent is necessary to ensure adequate disease management because different species may have distinct levels of aggressiveness and host range. One of the most important potato pathogens is Pectobacterium carotovorum, a highly heterogeneous species capable of infecting multiple hosts. The complexity of this species, until recently divided into several subspecies, has made it difficult to develop precise diagnostic tests. This study proposes a PCR assay based on the new pair of primers Pcar1F/R to facilitate the identification of potato isolates of P. carotovorum according to the most recent taxonomic description of this species. The new primers were designed on a variable segment of the 16S rRNA gene and the intergenic spacer region of available DNA sequences from classical and recently established species in the genus Pectobacterium. The results of the PCR analysis of genomic DNA from 32 Pectobacterium and Dickeya strains confirmed that the Pcar1F/R primers have sufficient nucleotide differences to discriminate between P. carotovorum and other Pectobacterium species associated with damage to potato crops, with the exception of Pectobacterium versatile, which improves the specificity of the currently available primers. The proposed assay was originally developed as a conventional PCR but was later adapted to the real-time PCR format for application in combination with the existing real-time PCR test for the potato-specific pathogen Pectobacterium parmentieri. This should be useful for the routine diagnosis of potato soft rot., Escalera de Excelencia” Programme Grant/Award Number: CLU-2017-03 P.O. FEDER of Castilla y León Grant/Award Number: 14-20

In a bioprospecting study of paramo soils cultivated with potato (Solanum tuberosum), 50 fungal isolates were obtained and evaluated for their nitrate reductase (NR) activity, given the role played by this enzyme in the biosynthesis of silver nanoparticles (AgNps). Five isolates strain with high NR activity belonging to Penicillium simplicissimum, Aspergillus niger, and Fusarium oxysporum species were selected, verifying the presence of the NR enzyme in their enzymatic extract. Later, these strains showed the ability to biosynthesize AgNps with distorted spherical shapes and sizes ranging from 15 to 45 nm. Subsequently, an antibiosis test was carried out by the agar diffusion method using glass fiber disks against the phytopathogenic agent Pectobacterium carotovorum, finding halos of inhibition of bacterial growth up to 15.3 mm using a 100 ppm solution of the AgNps obtained from F. oxysporum. These results contribute to generating the basis of a new alternative for the control of this phytopathogenic agent of potato, challenging to manage by traditional methods and of relevance at the post-harvest level.

Multidrug resistance (MDR) is a major concern in battling infectious bacterial diseases. The overuse of antibiotics contributes to the emergence of resistance by eradicating the drug-sensitive strains, leaving behind the resistant strains that multiply without any competition. Nanoparticles are becoming popular as novel antimicrobial agents that follow a different mode of action from standard antibiotics and are therefore desirable against MDR bacteria. In this study, we synthesized carbon dots from different precursors including glucosamine HCL (GlcNH2·HCl) and 4,7,10-trioxa-1,13-tridecanediamine (TTDDA, and studied their antimicrobial effects in a diverse list of Gram-negative bacteria including Escherichia coli, Pseudomonas syringae, Salmonella enterica subsp. enterica serovar Typhimurium, Pectobacterium carotovorum, Agrobacterium tumefaciens, and Agrobacterium rhizogenes. We demonstrated the antimicrobial properties of these carbon dots against these bacteria and provided the optimum concentration and incubation times for each bacterial species. Our findings indicated that not all carbon dots carry antimicrobial properties, and there is also a variation between different bacterial species in their resistance against these carbon dots.

Soft rot caused by Pectobacterium sp. is responsible for significant losses in vegetable production worldwide. Methods for the effective control of soft rot are limited and are primarily based on good agricultural practices. The use of bacteriophages as biocontrol agents appears to be a promising alternative to combat phytopathogens. In this study, we investigated the efficacy of lytic phages recovered from symptomatic tissues and environmental samples against soft rot caused by Pectobacterium carotovorum subsp. carotovorum. Three bacteriophage isolates, designated as vB_PcaP-A3, vB_PcaM-D1, and vB_PcaM-J3, were observed to effectively lyse P. carotovorum subsp. carotovorum. Phage vB_PcaP-A3 exhibited virion morphology similar to the members of the podovirus group, while phages vB_PcaM-D1 and vB_PcaM-J3 showed myovirus morphology based on transmission electron microscopy. The optimal multiplicity of infection (MOI) differed greatly among the three phages. All three phages survived incubations at 30°C, 40°C and 50°C and pH conditions ranging from 3.0 to 9.0, but were all inactivated at 60°C and at pH 12. Both monophage and cocktail preparations were effective in inhibiting the growth of P. carotovorum subsp. carotovorum in the in vitro challenge tests. In the semi-in planta assays, while treatment with cocktail preparations completely inhibited the development of soft rot in tissue slices, monophage treatments not only resulted in significant reduction of tissue maceration in slices, but also showed protective effect against soft rot in tubers. Overall, these results demonstrate the efficacy of phages vB_PcaP-A3, vB_PcaM-D1, and vB_PcaM-J3 for the biocontrol of soft rot caused by P. carotovorum subsp. carotovorum.

Pectobacterium and Dickeya species are the causal agents of blackleg and soft rot diseases in potatoes. The main pathogenic species identified so far on potatoes are Dickeya dianthicola, Dickeya solani, Pectobacterium atrosepticum, Pectobacterium brasiliense, Pectobacterium carotovorum, and Pectobacterium parmentieri. Ten years ago, the most prevalent Soft Rot Pectobacteriaceae in Europe were the Dickeya species, P. atrosepticum and P. carotovorum, with some variations among countries. Since then, a drastic increase in the abundance of P. brasiliense has been observed in most European countries. This shift is difficult to explain without comparing the pathogenicity of all Dickeya and Pectobacterium species. The pathogenicity of all the above-mentioned bacterial species was assessed in field trials and in vitro tuber slice trials in Switzerland. Two isolates of each species were inoculated by soaking tubers of cv. Desiree in a suspension of 105 CFU/mL, before planting in the field. For all trials, the Dickeya species were the most virulent ones, but long-term strain surveys performed in Switzerland indicate that P. brasiliense is currently the most frequent species detected. Our results show that the pathogenicity of the species is not the main factor explaining the high prevalence of P. brasiliense and P. parmentieri in the Swiss potato fields.

Biotic stress caused by pathogenic microorganisms leads to damage in crops. Tomato and carrot are among the most important vegetables cultivated worldwide. These plants are attacked by several pathogens, affecting their growth and productivity. Fourteen plant growth-promoting actinomycetes (PGPA) were screened for their in vitro biocontrol activity against Solanum lycopersicum and Daucus carota microbial phytopathogens. Their antifungal activity was evaluated against Fusarium oxysporum f. sp. radicis-lycopersici (FORL) and Rhizoctonia solani (RHS). Antibacterial activity was evaluated against Pseudomonas syringae, Pseudomonas corrugata, Pseudomonas syringae pv. actinidiae, and Pectobacterium carotovorum subsp. carotovorum. Strains that showed good in vitro results were further investigated in vitro (cell-free supernatants activity, scanning electron microscope observations of fungal inhibition). The consortium of the most active PGPA was then utilized as biocontrol agents in planta experiments on S. lycopersicum and D. carota. The Streptomyces albidoflavus H12 and Nocardiopsis aegyptica H14 strains showed the best in vitro biocontrol activities. The diffusible and volatile compounds and cell-free supernatants of these strains showed both antifungal (in vitro inhibition up to 85%, hyphal desegregation and fungicidal properties) and antibacterial activity (in vitro inhibition &gt, 25 mm and bactericidal properties). Their consortium was also able to counteract the infection symptoms of microbial phytopathogens during in planta experiments, improving plant status. The results obtained highlight the efficacy of the selected actinomycetes strains as biocontrol agents of S. lycopersicum and D. carota.

Pectobacterium spp. are a major cause of loss in vegetable and ornamental plant production. One of these species, Pectobacterium carotovorum, can cause soft rot disease on many plants, particularly potato. These diseases lead to significant economic loss and pose food security threats by reducing crop yields in the field, in transit, and during storage. The Gram-negative enterobacterium P. carotovorum WPP14 is a particularly virulent strain for which there is no available closed genome, limiting the molecular research for this important pathogen. Here, we report a high-quality complete and annotated genome sequence of P. carotovorum WPP14. The 4,892,225-bp genome was assembled with Nanopore reads and polished with Illumina reads, yielding 394× and 164× coverage, respectively. This closed genome provides a resource for research on improved detection and biology of P. carotovorum, which could translate into improved disease management.

Plant diseases are important issues in agriculture, and the development of effective and environment-friendly means of disease control is crucial and highly desired. Antimicrobial peptides (AMPs) are known as potential alternatives to chemical pesticides because of their potent broad-spectrum antimicrobial activity and because they have no risk, or have only a low risk, of developing chemical-resistant pathogens. In this study, we designed a series of amphipathic helical peptides with different spatial distributions of positive charges and found that the peptides that had a special sequence pattern “BBHBBHHBBH” (“B” for basic residue and “H” for hydrophobic residue) displayed excellent bactericidal and fungicidal activities in a wide range of economically important plant pathogens. The peptides with higher helical propensity had lower antimicrobial activity. When we modified the peptides with a long acyl chain at their N-terminus, their plant protection effect improved. Our application of the fatty acyl-modified peptides on the leaves of tomato and Arabidopsis plants lessened the infection caused by Pectobacterium carotovorum subsp. carotovorum and Botrytis cinerea. Our study provides important insights on the development of more potent novel AMPs for plant protection.

Soft rot on potato tuber is a destructive disease caused by pathogenic bacterial species of the genera

BACKGROUND Copper agents have been widely used in crop protection because of their unique mechanism against resistant pathogenic bacteria; however, their application brings environmental pollution and biosafety problems. Therefore, environmentally friendly copper agents have attracted attention. In this study, copper sulfide nanoparticles (CuS NPs) were prepared, characterized, analyzed for antibacterial activity and safety. RESULTS Characterization results showed that the prepared pure CuS NPs have flake nanostructures, hexagonal crystal system, and size range from 40 to 60 nm. These CuS NPs exerted excellent antibacterial effects [median effective concentration (EC50 ) = 17 mg L-1 ] against Pectobacterium carotovorum subsp. carotovorum (Pcc) in vitro and can effectively delay and reduce bacterial infection in vivo. Antibacterial mechanism analysis revealed that CuS NPs can increase the levels of reactive oxygen species (ROS) and lipid peroxidation and destroy the structure of bacterial cells as observed through scanning electron microscopy (SEM) and Fourier-transform infrared (FTIR) spectroscopy. These NPs can also inhibit the motility of Pcc. At 7 and 14 days, the 50% lethal concentrations (LC50 ) of CuS NPs against earthworms were 1136 and 783 mg kg-1 , respectively, indicating their low acute toxicity to earthworms and environmental friendliness. Furthermore, the cells (L02) treated by CuS NPs showed relatively high cell viability (> 96%) and low apoptosis rate (only 5.2%), proving that CuS NPs had low cytotoxicity. CONCLUSION Compared with commercial dicopper chloride trihydroxide (Cu2 (OH)3 Cl), CuS NPs could be used as a highly effective, lowly toxic, and environmentally friendly antibacterial agent.

Potato blackleg is frequently observed on the production fields in the Backa region of Vojvodina province, which is one of the largest potato-growing areas in Serbia. This disease usually occurs during June and July. In July 2020, blackleg symptoms in the form of stem necrotic lesions, vascular discoloration, hollow stems, and wilting of whole plants were noted on potato cultivar VR808 on a field 28 ha in size located in Maglic village (GPS coordinates 45.349325 N, 19.542768 E). Disease incidence was estimated at 20-25%. Isolations were performed from 12 potato samples on Crystal Violet Pectate medium (CVP). Stem sections consisted of brown lesions and healthy tissue (c.10 cm) were surface sterilized with ethyl alcohol 70% (w/v) and rinsed with sterile distilled water. Small pieces of tissue were taken at the edges of stem lesions (between healthy and diseased tissue) were soaked in phosphate buffer saline for 20 min and plated using a standard procedure (Klement et al. 1990). Single colonies that formed pits after 48 hours at 26 °C were re-streaked onto Nutrient Agar (NA) where creamy white colonies with smooth surfaces were formed. A total of 30 isolates were selected and DNA isolated from the colonies was further analyzed by polymerase chain reaction (PCR) using the partial dnaX gene (DNA polymerase subunit III gamma/tau) with primer pair dnaXf/dnaXr for Pectobacterium and Dickeya species identification (Slawiak et al. 2009). A single characteristic band of 535 bp was amplified in all isolates (Slawiak et al. 2009). DNA sequence alignment showed two distinct groups of isolates (Fig.S1), which were genetically uniform within each group. Using BLASTn search, it was established that the dnaX sequence of the first group (consisting of 19 Serbian potato isolates) had 99.79% identity with NCBI-deposited Pectobacterium versatile strains 14A and 3-2 from potato from Belarus (Acc. No. CP034276 and CP024842, respectively) as well as SCC1 from Finland (Acc. No. CP021894). The remaining 11 dnaX sequences had 100% identity with Pectobacterium carotovorum subsp. carotovorum strain CFBP7081 originating from water in Spain (Acc. No. MK516961). The partial dnaX sequences of three Serbian P. versatile isolates (Pv1320, Pv1520, and Pv1620) and one P. carotovorum subsp. carotovorum (Pcc2520) were deposited in GenBank under Acc. No. MW839571, MW805306, MW839572, and MW805307, respectively. These results, indicating combined infection in the observed field, signify the first identification of P. versatile in Serbia. Multilocus sequence analysis (MLSA) performed with proA (proAF1/ proAR1) and mdh (mdh2/mdh4) genes (Ma et al. 2007; Moleleki et al. 2013) grouped three tested Serbian potato P. versatile isolates together with P. versatile strains from NCBI (Fig.S2). For both tested genes, BLASTn search revealed 100% homology with P. versatile strain SCC1 from Finland. Three Serbian P. versatile potato isolates were deposited under Acc. Nos. MZ682623-25 for proA and MZ682620-22 for mdh genes. According to the routine tests suggested for Pectobacteriaceae (Schaad et al. 2001), Serbian isolates possessed microbiological traits identical to P. versatile description (Portier et al. 2019). Pathogenicity was performed on potato cultivar VR808 with three selected P. versatile isolates (Pv1320, Pv1520, and Pv1620) in the following assays: (i) surface-sterilized tuber slices with holes in the center filled with 100 µL of bacterial suspensions (adjusted to 109 CFU mL-1) to test the isolates' ability to cause soft rot, and (ii) young, four-week old plants with developed 3rd true leaf (c. 30 cm tall) were inoculated by injecting stems with bacterial suspension adjusted to 107 - 108 CFU mL-1 at a height 5 cm above the soil line. Negative controls were treated with sterile distilled water. Inoculated plants were kept under controlled conditions (25 °C temperature and >70% relative humidity). Each assay was replicated twice. Soft rot appeared on tuber slices 24 h after inoculation. On inoculated stems, initial symptoms manifested as greasy elongated spots at inoculation sites two days after inoculation (DAI), and subsequently extended along the vascular tissue and became necrotic. Whole plant's decay was recorded in five DAI, while negative controls remained healthy. To complete Koch's postulates, bacteria were re-isolated from symptomatic potato plants and confirmed by PCR and sequencing of dnaX. This first report of P. versatile in potato indicates that blackleg currently present in Serbia is caused by a diverse bacterial population. This pathogen was first identified in genome comparison as 'Candidatus Pectobacterium maceratum' (Shirshikov et al. 2018) and was later renamed as Pectobacterium versatile sp. nov. (Portier et al. 2019). Thus far, bacterium Pectobacterium carotovorum subsp. brasiliensis has been recognized as dominant pathogen on most of the infected fields in Vojvodina province, and was recently noted on one plot subjected to a combined infection with Dickeya dianthicola (Markovic et al. 2021). Findings achieved in this study are highly relevant, as they point to the diversity in potato blackleg pathogens, likely due to the increasingly widespread distribution of imported seed potatoes.

Pectinolytic enzymes (pectinases) produced by microbes are highly important for their biotechnological use in processing of vegetables and fruits beverages and use in pulp and paper industry. A pectinase, namely endo-polygalacturonase (endo-PGase), encoding gene isolated from Pectobacterium carotovorum, a plant pathogenic strain of bacteria was successfully cloned into a secretion vector pHT43 having σA-dependent promoter P grac. For enhanced expression analysis, competent cells of Bacillus subtilis (WB800N) were prepared at stationary phase using high salt medium. The recombinant B. subtilis competent cells, harbouring the engineered pHT43 with the endo-PGase gene were cultured in 2X-yeast extract tryptone medium. The recombinant endo-PGase enzyme was secreted directly into the medium after 72 hours of the first IPTG induction. The recombinant endo-PGase was screened for its activity at various temperatures and pH ranges. Optimal activity was found at pH 5.0 and a temperature of 40°C with a stability ranging from pH 5.0-9.0. For detection of metal ion effect, recombinant enzyme was incubated with 1mM concentration of; Ca++, Mg++, Zn++, EDTA, K++ for 45 minutes. Resultantly, Ca++, EDTA and Zn++ strongly inhibited the enzyme activity. The chromatographic analysis of enzymatic hydrolysate of polygalacturonic acid (PGA) and pectin substrates using HPLC and TLC revealed that tri and tetra-galacturonates were the end products of hydrolysis. The study led to the conclusion that endo-PGase gene from the plant pathogenic strain was successfully expressed in Bacillus subtilis and could be assessed for enzyme production using a very simple medium with IPTG induction. These findings proposed that the Bacillus expression system might be safe for commercial enzyme production as compared to yeast and fungi to escape endotoxins.

Bacterial soft rot is a destructive disease that restricts the development of the konjac (Amorphophallus konjac K. Koch ex N.E.Br) industry. The objective of this study was to investigate how soft rot disease affects bacterial communities associated with the roots of konjac plants growing under a pure Robinia pseudoacacia plantation. Three sampling sites affected by different degrees of soft rot damage were selected based on the disease incidence [0%, non-diseased (ND); 4.2%, moderately diseased (MD); and 18.6%, highly diseased (HD)]. The variation in soil and root bacterial diversity and community composition among the sampling sites was determined by Illumina HiSeq sequencing of the V3–V4 hypervariable regions of the bacterial 16S rRNA gene. The results showed that the contents of soil organic matter and available nutrients (N, P, and K) increased with increasing damage degree, whereas higher damage degree resulted in lower soil pH and enzymatic activity (sucrase, urease, catalase, and polyphenol oxidase). The composition of root-associated bacterial communities differed among the three sampling sites. Proteobacteria was the most dominant bacterial phylum in all soil and root samples. Pseudomonas, Bacillus, Rhizobium, and Streptomyces were the most abundant in all samples from the ND sites, whereas Pectobacterium carotovorum and Serratia were predominant in the samples from the MD and HD sites. The abundance and alpha diversity of root-associated bacteria were significantly higher (p < 0.05) in the ND sites than in the diseased sites. The results suggested pronounced differences in the abundance, alpha diversity, and community composition of bacteria associated with the roots of konjac plants affected by different degrees of soft rot damage. Such differences in bacterial community structure were related to dynamic changes in soil variables, especially soil available potassium content, sucrase activity, and urease activity. Analysis of the dominant root-associated bacterial taxa offers an approach to predict the damage degree due to soft rot in konjac and provides evidence for the prevention of this soil-borne disease via microecological regulation.

Bacterial soft rot is one of the major destructive diseases affecting crop production worldwide. In summer 2017, soft rot of fruit and stem blight was observed on bell pepper in commercial fields in south Georgia, USA. Bacteria were isolated from infected fruits and stems, and 5 isolates (MPS05, MPS06, PF01–2, PF04–3 and PF05–3) were characterized in the study. The isolates were identified as Pectobacterium carotovorum subsp. brasiliense (Pcb) and P. aroidearum (Pa) by morphological characteristics, biochemical and physiological tests, PCR amplification using Pcb-specific primers, and phylogenetic analysis of the 16S rDNA sequences. Pathogenicity tests on bell pepper seedlings indicated that isolates MPS05 (Pcb) and PF05–3 (Pa) were aggressive, causing plant tissue discoloration, lesions on leaves and stems, plant wilt and death. Inoculation of bell pepper fruit with MPS05 and PF05–3 at different concentrations (105, 106, 107 and 108 CFU/ml) resulted in fruit tissue maceration and complete fruit rot. To our knowledge, this study is the first report of disease caused by P. carotovorum subsp. brasiliense on pepper in the United States and the first report of P. aroidearum causing disease on pepper in the world.

Saccharin is generated from probenazole (PBZ) in plants and acts as a plant defense activator. Our study of the mechanism underlying saccharin-induced systemic acquired resistance in Arabidopsis thaliana suggests an antagonistic interaction between salicylic acid (SA)- and jasmonic acid (JA)-signaling as revealed through gene expression analyses. In wild-type plants (Col-0) exposed to saccharin, there was a consistent increase in callose deposition and in expression of SA-marker genes, PR1 and PR2, which coincided with a decrease in expression of JA-marker genes such as VSP2, LOX2 and PDF1.2. Actually, pretreatment of Col-0 with saccharin or PBZ conferred resistance to Pseudomonas syringae pv. tomato DC3000, but not to Pectobacterium carotovorum subsp. carotovorum, Botrytis cinerea, or Colletotrichum higginsianum. Enhanced expression of SA- and JA-marker genes and the augmented deposition of callose were evident after a challenge with virulent DC3000 in saccharin-pretreated plants. Consistently, pretreatment of saccharin and PBZ with SA- and JA-defective mutants led to diminished resistance in NahG-transgenic and npr1 mutant plants, but not in jar1 mutant plants, suggesting that saccharin and PBZ induce resistance in A. thaliana against Pto DC3000 mainly via activation of SA-signaling, leading to suppression of JA/ET-signaling and vice versa. Collectively, an antagonism between SA- and JA-signaling conditioned by saccharin renders resistance to a specific pathogen in Arabidopsis.

Background. At present, the problem of plant colonization by bacteria pathogenic for human is of particular interest. Among the bacteria capable of polyhostality, species of the Enterobacteriaceae family, which includes both phytopathogenic and human pathogens, are of particular interest. Fruits and vegetables contaminated with such pathogens have been shown to be able to cause human intestinal infections. Being one of the ways of communication in the plantmicroorganism system, it is possible that the synthesis of indole acetic acid (IAA) by Enterobacteriaceae determines the growth rate of bacteria, contributing to more rapid colonization of the plant.Aim: comparative study of the synthesis of IAA by different types of enterobacteria.Methods. Eight types of enterobacteria were used in the study, seven of which were isolated from sick people, as well as the phytopathogen Pectobacterium carotovorum spp. carotovorum. The work was performed using microbiological and spectrophotometric research methods.Results. The ability of the synthesis of IAA by opportunistic microorganisms belonging to the Enterobacteriaceae family was studied. We found that the majority of the studied strains synthesize IAA. Studies on the effect on the synthesis of IAA, the introduction into the nutrient medium of tryptophan and its enrichment with glucose, as well as the variation of the temperature regime of the cultivation of bacteria were carried out.

Diseases of carrot (Daucus carota L.) that cause yield losses include bacterial soft-rot incited by Pectobacterium carotovorum pv. carotovorum (Jones) Waldee; bacterial leaf blight incited ...

Blackleg and soft rot of potato cause economic loss through reduced yield and quality. The causal agents of bacterial blackleg and soft rot of potato were identified based on biological data and sequence analyses of the 16S rDNA gene. Between 2016 and 2018, diseased potato stems and tubers were collected in Chai Prakan District, Chiang Mai Province, and Chiang Khum District, Pa Yao Province. The symptoms included black stem lesions, soft rot on tubers, wilting, break down of the stem vascular ring and foliar yellowing. Of 13 bacterial isolates, five were identified as Pectobacterium carotovorum subsp. brasiliense, four‐Dickeya dadantii, two‐Pseudomonas putida and two‐Bacillus altitudinis. Pathogenicity tests of P. carotovorum subsp. brasiliense and D. dadantii resulted in lower leaves turning yellow and wilting followed by blackleg symptoms on lower stems and maceration of tuber tissue. Symptoms caused by P. putida were yellowing and wilting of leaves. B. altitudinis caused yellowing of the lower leaves and wilting followed by drying of leaf tissue. This is a first report of these bacterial pathogens causing blackleg and soft rot of potato in Thailand.

In this study, an antagonistic yeast isolate, Wickerhamiella versatilis was considered as a promising biocontrol agent against Pectobacterium carotovorum subsp. Carotovorum (Pcc) the causal...

Cross-contamination of Pectobacterium carotovorum subsp. carotovorum (PCC) from a stainless-steel surface to cabbage (Brassica rapa L. subsp. pekinensis) was evaluated. To investigate the PCC transfer pattern from mechanical knife surfaces to cabbage during 100 cuts, two mathematical models (power and logarithmic model) were fitted to the mean log10 detection data from cabbage. Overall, regression analysis determined that the best-fitting regression curves of planktonic cells and detached cells from biofilms transferred onto fresh cabbage were Y = 3.7X-0.41 , RMSE = 0.371 and Y = 4.6X-0.35 , RMSE = 0.254, respectively. For salted cabbage, the best-fit regression curves of planktonic cells and biofilm were Y = 5.8X-0.38 , RMSE = 0.209 and Y = 5.4X-0.23 , RMSE = 0.195, respectively. Our data provide a meaningful indication of the level of PCC cross-contamination.

The integral defense responses of plants triggered by the small molecules of plant pathogens are regarded as plant immunity. The pathogen-associated molecular pattern-triggered immunity (PTI) occurs on the recognition of a pathogen by receptors on plant cell surfaces as an infection begins. During the activation of PTI, the effectiveness of a plant’s photosynthetic system may be altered. In this study, chlorophyll fluorescence was used to assay the dynamic changes of PTI. When we used flg22Pst as an elicitor, we found that the photosynthetic electron transport rate (ETR) of Arabidopsis thaliana Col-0 was significantly decreased at 2, 4, and 24 h on treatment with a PTI-intensifying protein, plant ferredoxin-like protein (PFLP). In addition, this reduction in the photosynthetic ETR was also carried out with a PTI-intensifying Bacillus amyloliquefaciens strain, PMB05, on the induction of flg22Pst. The disease resistance against bacterial soft rot caused by Pectobacterium carotovorum subsp. carotovorum (Pcc) was still enhanced by PMB05. Interestingly, among the eight tested Bacillus species strains, the PTI triggered by HrpNPcc from P. carotovorum subsp. carotovorum exhibited an ETR that was significantly decreased by PMB05. Furthermore, this decrease was consistent with rapid H2O2 generation and callose deposition triggered by HrpNPcc and the disease resistance against bacterial soft rot. Taken together, such results led us to conclude that the assay based on the ETR established in this study can be used as a model for evaluating the effectiveness of plant immunity-intensifying microbes for controlling plant diseases.

Seven bacterial isolates were isolated and identified from green onion and mature bulb (Allium cepa L.) that showing naturally infected soft rot disease. Onion samples used for isolation were collected from different super markets and store houses of Abou-Hamad District, Sharkia Governorate, during 2016/2017 seasons. Seven isolates showed different degree of aggressive pathogenic capability on onion bulbs. Morphological, physiological and biochemical diagnostic properties of the seven bacterial isolates confirmed that one isolate identified as Bacillus polymyxa, three isolates as Pseudomonas cepacia and three isolates as Pectobacterium carotovorum subsp. carotovorum. The seven identified bacterial isolates were compared for their degree of pathogenic capabilities in some different plant hosts. With the exception of chili fruits, the seven bacterial isolates were able to infect fruits, tubers, pods and roots of seventeen host plant species related to seven plant genera. Percentage of rotted onion bulb during storage significantly affected by the packing materials that used in preparing storage package, onion cultivar, maturity of bulb, type of cultivated soil and storage time. Results revealed that good control against onion soft rot could be obtained when mature bulbs of resistant cultivar cultivated in clay soil conducted to good cure program and stored under low temperature and high ventilation conditions.

Phages of the phytopathogenic Pectobacteriaceae species causing black leg and soft rot of potato were investigated. These phages are promising as biocontrol agents to prevent the loss of seed and ware potato tubers. The present work characterizes a new podovirus PP16, infecting a broad range of Pectobacterium carotovorum strains. Based on its genomic composition, phage PP16 was assigned to a separate phylogenetic branch of the genus Phimunavirus, subfamily Autographivirinae. Bacteriophage PP16 efficiently inhibited development of bacterial infection both in vitro and in planta. The field experiment demonstrated a substantial increase of plant germination after the treatment of seed potato with phage PP16.

Background Pectobacterium carotovorum subsp. brasiliense is a broad host range bacterial pathogen, which causes blackleg of potatoes and bacterial soft rot of vegetables worldwide. Production of plant cell wall degrading enzymes is usually critical for Pectobacterium infection. However, other virulence factors and the mechanisms of genetic adaptation still need to be studied in detail. Results In this study, the complete genome of P. carotovorum subsp. brasiliense strain SX309 isolated from cucumber was compared with eight other pathogenic bacteria belonging to the Pectobacterium genus, which were isolated from various host plants. Genome comparison revealed that most virulence genes are highly conserved in the Pectobacterium strains, especially for the key virulence determinants involved in the biosynthesis of extracellular enzymes and others including the type II and III secretion systems, quorum sensing system, flagellar and chemotactic genes. Nevertheless, some variable regions of the T6SS and the CRISP-Cas immune system are unique for P. carotovorum subsp. brasiliense. Conclusions The extensive comparative genomics analysis revealed highly conserved virulence genes in the Pectobacterium strains. However, several variable regions of type VI secretion system and two subtype Cas mechanism-Cas immune systems possibly contribute to the process of Pectobacterium infection and adaptive immunity. Electronic supplementary material The online version of this article (10.1186/s12864-019-5831-x) contains supplementary material, which is available to authorized users.

The effects of graphene oxide (GO) and zinc oxide (ZnO) nanoparticles (NPs) at two concentrations, i.e., 0.05 mg ml−1 and 0.10 mg ml−1 were observed on Pectobacterium carotovorum, Xanthomonas campestris pv. carotae, Meloidogyne javanica, Alternaria dauci and Fusarium solani on the growth of carrot (Daucus carota). Specific physiological variables studied include chlorophyll, carotenoid and proline contents. Inoculation of plants with P. carotovorum, X. campestris pv. carotae, M. javanica, A. dauci and F. solani reduced plant growth and chlorophyll and carotenoid contents but increased proline contents. Application of GO or ZnO NPs to plants with or without pathogens caused significant increases in plant growth, chlorophyll, carotenoid and proline contents. ZnO NPs were more effective than GO NPs in increasing plant growth, chlorophyll, carotenoid and proline contents. The 0.10 mg ml−1 concentration of both NPs was more effective in increasing plant growth, chlorophyll, carotenoid and proline contents than the 0.05 mg ml−1 concentration. Galling and multiplication of M. javanica was reduced by NPs application. ZnO NPs at concentration, 0.10 mg ml−1 caused highest reduction in galling and nematode multiplication and GO NPs at 0.05 mg ml−1 the least. Soft rot, bacterial leaf blight, leaf spot and root rot indices caused by P. carotovorum, X. campestris pv. carotae, A. dauci and F. solani respectively were 4. Disease indices were reduced to 2 when 0.05 and 0.10 mg ml−1 GO and 0.05 mg ml−1 ZnO were sprayed onto plants with test pathogens. Indices were highly reduced to 1 when 0.10 mg ml−1 ZnO was sprayed onto plants with test pathogens.

Plants are exposed to biotic stresses caused by pathogen attack and complex abiotic stresses including heat and drought by dynamic climate changes. To alleviate these stresses, we investigated two bacterial stains, H26-2 and H30-3 in two cultivars ('Ryeokkwang' and 'Buram-3-ho') of Chinese cabbage in plastic pots in a greenhouse. We evaluated effects of bacterial strains on plant growth-promotion and mitigation of heat and drought stresses; the role of exopolysaccharides as one of bacterial determinants on alleviating stresses; biocontrol activity against soft rot caused by Pectobacterium carotovorum subsp. carotovorum PCC21. Strains H26-2 and H30-3 significantly increased fresh weights compared to a MgSO4 solution; reduced leaf wilting and promoted recovery after re-watering under heat and drought stresses. Chinese cabbages treated with H26-2 and H30-3 increased leaf abscisic acid (ABA) content and reduced stomatal opening after stresses treatments, in addition, these strains stably colonized and maintained their populations in rhizosphere during heat and drought stresses. As well as tested bacterial cells, exopolysaccharides (EPS) of H30-3 could be one of bacterial determinants for alleviation of tested stresses in Chinese cabbages, however, the effects were different to cultivars of Chinese cabbages. In addition to bacterial activity to abiotic stresses, H30-3 could suppress incidence (%) of soft rot in 'Buram-3-ho'. The tested strains were identified as Bacillus aryabhattai H26-2 and B. siamensis H30-3 based on 16S rRNA gene sequence analysis. Taken together, H26-2 and H30-3 could be candidates for both plant growth promotion and mitigation of heat and drought stresses in Chinese cabbage.

Herein, the catalytic efficiency and thermal stability of l -Asparaginase (ASN, EC 3.5.1.1) from Bacillus subtilis 168 were enhanced by modifying its N-terminus highly flexible loop. A continuous non-conserved region (residues20–29) within the N-terminal loop of the ASN was identified and substituted with the structurally equivalent region of ASNs from Escherichia coli, Helicobacter pylori, Wolinella succinogenes, Pseudomonas aeruginosa, Erwinia chrysanthemi, and Pectobacterium carotovorum, yielding the ASN loop variants L1, L2, L3, L4, L5, and L6, respectively. In contrast to the wild-type enzyme, L6 exhibited the highest increase (2.1-fold) in specific activity. Molecular dynamics analysis suggested a negative correlation between the flexibility of the continuous non-conserved region and specific activity. Saturation mutagenesis and complex mutation on flexible residues Ala26 and Gly29 of L6 obtained a double variant L6-A26N/G29F with 3.44-fold and 7.76-fold increases in specific activity and half-life at 65 °C in comparison with wild-type enzyme, respectively. As suggested by structural analysis, the reduced flexibility of the continuous non-conserved region benefit the correct orientation of the active site Thr16 and closure of the substrate pocket. Our results demonstrated that reducing the flexibility of the highly flexible loop was an efficient method to enhance the catalytic efficiency and thermal stability of ASN.

Solanum tuberosum, commonly known as the potato, is a worldwide food staple. During harvest, storage, and distribution the crop is at risk of mechanical damage. Wounding of the tuber skin can also become a point of entry for bacterial and fungal pathogens, resulting in substantial agricultural losses. Building on the proposal that potato tubers produce metabolites to defend against microbial infection during early stages of wound healing before protective suberized periderm tissues have developed, we assessed extracts of wound tissues from four potato cultivars with differing skin morphologies (Norkotah Russet, Atlantic, Chipeta, and Yukon Gold). These assays were conducted at 0, 1, 2, 3 and 7 days post wounding against the plant pathogen Erwinia carotovora and a non-pathogenic Escherichia coli strain that served as a control. For each of the potato cultivars, only polar wound tissue extracts demonstrated antibacterial activity. The polar extracts from earlier wound-healing time points (days 0, 1 and 2) displayed notably higher antibacterial activity against both strains than the later wound-healing stages (days 3 and 7). These results support a burst of antibacterial activity at early time points. Parallel metabolite profiling of the extracts revealed differences in chemical composition at different wound-healing time points and allowed for identification of potential marker compounds according to healing stage for each of the cultivars. It was possible to monitor the transformations in the metabolite profiles that could account for the phenomenon of temporal resistance by looking at the relative quantities of various metabolite classes as a function of time.

Neobuxbaumia tetetzo (Coulter) Backeberg (tetecho) is a columnar cactus endemic to Mexico. Tetecho plants, flowers, fruits, and seeds play an important role in the semiarid ecosystem, as they serve as a refuge and food for insects, bats, and birds, and are widely used by ethnic groups since pre-Hispanic times. Tetecho is affected by a soft rot that damages the whole plant and causes its fall and disintegration. Eight bacterial colonies of similar morphology were isolated from plants showing soft rot and inoculated in healthy tetecho plants, reproducing typical symptoms of soft rot 9 days after inoculation. Ten representative isolates were selected for phenotypic and genetic identification using 16s rDNA, IGS 16S-23S rDNA, and rpoS genes and for pathogenicity tests on several members of the cactus family and other plants. Based on the results, these bacterial isolates were identified as Pectobacterium carotovorum subsp. brasiliense. Inoculation of this bacteria caused soft rot in different cacti, fruits, leaves, and roots of other plants. This is the first report of the subspecies brasiliense of P. carotovorum causing soft rot and death in cacti in the world and the first report of this subspecies in Mexico.