Carotovora Subsp Research Articles

Early asymptomatic prediction of potato soft rot disease using phytohormone-induced volatile biomarkers.

Potatoes (Solanum tuberosum L.) are one of the world's major staple crops. In stored potatoes, Pectobacterium carotovorum subsp carotovorum causes soft rot. As a result of the rapid spread of the disease during post-harvest storage, potato production suffers huge losses. By detecting disease early and controlling it promptly, losses can be minimized. The profile of volatiles of plants can be altered by phytopathogens. Identifying unique volatile organic compounds (VOCs) as biomarkers for early disease detection has attracted considerable research attention. This study compared the VOC profiles of healthy and soft rot inoculated potatoes (cv. "Kufri Pukhraj") over a time course using gas chromatography-mass spectrometry (GC-MS). It was found that there was a differential emission of 27 VOCs between healthy non-inoculated potatoes and soft rot inoculated potatoes. Among 27 VOCs, only five (1-octen-3-ol, 2-methylisoborneol, 3-octanone, 1,4-dimethyladamantane, and 2-methyl-2-bornene) were found exclusively in soft rot inoculated potatoes, suggesting them potential biomarker for non-destructive prediction of soft rot disease in potatoes. Reactive oxygen species (H2O2) and phytohormone methyl-jasmonate (MeJa) levels increased transiently on infection with soft rot. The analysis of the primary metabolism of soft rot infected tubers at three different stages suggests metabolic reprogramming that occurs at the early stage of infection, possibly leading to biomarker volatile emission. Based on these results, it appears that the initial potato-soft rot bacteria interaction initiates metabolic reprogramming mainly through H2O2 and the MeJa signalling pathway. In asymptomatic potatoes, these biomarkers may be promising candidates for non-destructive detection of soft rot at an early stage. These biomarkers can be used to develop an e-nose sensor to predict soft rot in the future.

Genome-Wide Identification and Expression Profile Analysis of Sugars Will Eventually Be Exported Transporter (SWEET) Genes in Zantedeschia elliottiana and Their Responsiveness to Pectobacterium carotovora subspecies Carotovora (Pcc) Infection.

SWEET, sugars will eventually be exported transporter, is a novel class of sugar transporter proteins that can transport sugars across membranes down a concentration gradient. It plays a key role in plant photosynthetic assimilates, phloem loading, nectar secretion from nectar glands, seed grouting, pollen development, pathogen interactions, and adversity regulation, and has received widespread attention in recent years. To date, systematic analysis of the SWEET family in Zantedeschia has not been documented, although the genome has been reported in Zantedeschia elliottiana. In this study, 19 ZeSWEET genes were genome-wide identified in Z. elliottiana, and unevenly located in 10 chromosomes. They were further clustered into four clades by a phylogenetic tree, and almost every clade has its own unique motifs. Synthetic analysis confirmed two pairs of segmental duplication events of ZeSWEET genes. Heatmaps of tissue-specific and Pectobacterium carotovora subsp. Carotovora (Pcc) infection showed that ZeSWEET genes had different expression patterns, so SWEETs may play widely varying roles in development and stress tolerance in Zantedeschia. Moreover, quantitative reverse transcription-PCR (qRT-PCR) analysis revealed that some of the ZeSWEETs responded to Pcc infection, among which eight genes were significantly upregulated and six genes were significantly downregulated, revealing their potential functions in response to Pcc infection. The promoter sequences of ZeSWEETs contained 51 different types of the 1380 cis-regulatory elements, and each ZeSWEET gene contained at least two phytohormone responsive elements and one stress response element. In addition, a subcellular localization study indicated that ZeSWEET07 and ZeSWEET18 were found to be localized to the plasma membrane. These findings provide insights into the characteristics of SWEET genes and contribute to future studies on the functional characteristics of ZeSWEET genes, and then improve Pcc infection tolerance in Zantedeschia through molecular breeding.

Trichoderma-derived emodin competes with ExpR and ExpI of Pectobacterium carotovorum subsp. carotovorum to biocontrol bacterial soft rot.

Quorum sensing inhibitors (QSIs) are an emerging control tool that inhibits the quorum sensing (QS) system of pathogenic bacteria. We aimed to screen for potential QSIs in the metabolites of Trichoderma and to explore their inhibitory mechanisms. We screened a strain of Trichoderma asperellum LN004, which demonstrated the ability to inhibit the color development of Chromobacterium subtsugae CV026, primarily attributed to the presence of emodin as its key QSI component. The quantitative polymerase chain reaction with reverse transcription results showed that after emodin treatment of Pectobacterium carotovorum subsp. carotovorum (Pcc), plant cell wall degrading enzyme-related synthetic genes were significantly downregulated, and the exogenous enzyme synthesis gene negative regulator (rsmA) was upregulated 3.5-fold. Docking simulations indicated that emodin could be a potential ligand for ExpI and ExpR proteins because it exhibited stronger competition than the natural ligands in Pcc. In addition, western blotting showed that emodin attenuated the degradation of n-acylhomoserine lactone on the ExpR protein and protected it. Different concentrations of emodin reduced the activity of pectinase, cellulase, and protease in Pcc by 20.81%-72.21%, 8.38%-52.73%, and 3.57%-47.50%. Lesion size in Chinese cabbages, carrots and cherry tomatoes following Pcc infestation was reduced by 10.02%-68.57%, 40.17%-88.56% and 11.36%-86.17%. Emodin from T. asperellum LN004 as a QSI can compete to bind both ExpI and ExpR proteins, interfering with the QS of Pcc and reducing the production of virulence factors. The first molecular mechanism reveals the ability of emodin as a QSI to competitively inhibit two QS proteins simultaneously. © 2023 Society of Chemical Industry.

Morpho-molecular Characterization of Carrot Soft Rot Incitant, Pectobacterium carotovorum subsp carotovoroum

Carrot is an important root vegetable which plays an important role in human health. Globally, Post harvest diseases are the major constraint in carrot production, especially soft rot which resulting in severe yield loss. Early diagnosis of these post-harvest diseases paves a way for reducing the economic losses. Carrot samples showing typical rotting symptoms were collected from markets of four different districts of Tamil Nadu and the pathogen involved were isolated. Severe carrot soft rot incidence (66.74%) was observed in samples collected from Ooty area of The Nilgiris district and the least disease incidence of (16.21%) was recorded in Perundurai of Erode district. Pathogenicity of soft rot pathogen were conducted and the virulent isolates were identified based on Percent Disease Index (PDI) showing >50% rotting falls under disease grade 9 using disease grade scale (0 to 9). The bacterial isolates (KPB-7 and OCB-5) causing soft rot were characterized using various biochemical assays where in they showed positive response for methyl red, H2S gas production, KOH and catalase tests besides showing negative response for gram’s reaction. Furthermore, molecular characterization of 16s rRNA region revealed the soft rot isolate (KPB-7) as Pectobacterium carotovorum subsp carotovorum (with an accession number OR251119).

First Report of Bark Split Disease Caused by Pectobacterium carotovorum on Artocarpus heterophyllus (Jackfruit) in China.

Jackfruit (Artocarpus heterophyllus) is widely cultivated in the tropical areas in the world. Jackfruit bark split disease occurred in the large-scale plantations of 18 cities and counties surveyed in Hainan since 2021, among which the incidence rate of serious orchards reached about 70%, and the mortality rate reached about 35%. Jackfruit bark split disease mainly harms tree branches and trunks, manifested as water stains, bark gumming, bark depression, bark cracking, and ultimately plant death. To identify the pathogen, Four samples with jackfruit bark split disease symptoms were collected, sterilized with 75% ethanol for 30 s, then soaked in 2% sodium hypochlorite (NaClO) for 5 mins, and finally rinsed continuously with sterilized distilled water. The sterilized tissues were placed on LB agar medium and incubated in illumination incubator at 28 ℃. Four milky white, round with neat edges, convex and smooth, translucent colonies were obtained. All isolates (JLPs-1 to JLPs-4) were Gram-negative, negative for oxidase, catalase and gelatin liquefaction. Amplification and sequencing of 16S rDNA gene from 4 isolates were conducted with the universal primers 27f /1492r (Lane et al. 1991). The BLASTn analysis of obtained JLPs-1 and JLPs-3 sequences (GenBank accession nos. OP942452 and OP942453) showed an identity percentage of 98.99% and 98.93% with Pectobacterium sp. (CP104733), respectively. Phylogenetic analysis based on 16S rDNA gene using the neighbor-joining method with MEGA 7.0 software revealed that JLPs-1 and JLPs-3 were clustered together with P. carotovorum reference strains. The four housekeeping genes gyrA, recA, rpoA and rpoS were partially sequenced for JLPs-1 isolates using primers gyrA1/gyrA4, recA1/recA2c, rpoS1/rpoS2 and rpoA F1/rpoA R1 (Loc et al. 2022), respectively. Multilocus sequence analyses identified the isolates from jackfruit as P. carotovorum. To further confirm the identification of Pectobacterium carotovorum, pelY gene, P. carotovorum subsp. Brasiliensis 16S-23S intergenic region (Pcb IGS) and P. carotovorum subsp. carotovorum (Pcc) specific fragment were amplified with primers Y1/Y2 (Darrasse et al. 1994), BR1f/L1r (Duarte et al. 2004) and EXPCCF/EXPCCR (Kang et al. 2003), respectively. A 540 bp target fragment was successfully amplified from JTPs only by EXPCCF/EXPCCR and there no bands for the other two primers. Pathogenicity test was performed in the field, and all the inoculated trees were 2-3-year-old 'Qiong Yin No.1' variety. Dense small holes were pierced with sterilized inoculation needle on four healthy jackfruit trees. Then punctured wounds were spraying-inoculated with bacteria suspension of JLPs-1 (108 CFU/ml), and finally wrapped with plastic wrap to moisturize. Two trees inoculated with sterile distilled water served as negative control. Typical symptoms of bark gumming, bark depression, bark cracking were observed on all of the inoculated trees at 17 dpi which just similar to those originally caused by P. carotovorum in the field, whereas negative control trees remained asymptomatic. The strains were re-isolated successfully from symptomatic jackfruit trees and were consistent with the biological and molecular biological characteristics of original strains, confirming that the pathogen of jackfruit bark split disease was Pectobacterium carotovorum. To our knowledge, this is the first report of P. carotovorum causing bark split disease on jackfruit in China.

Potential of bacteriophage PCT27 to reduce the use of agrochemicals to control Pectobacterium carotovorum subsp. Carotovorum in Chinese cabbage (Brassica pekinensis)

As antimicrobial resistance (AMR) continues to spread among bacteria and poses a serious threat to global health, the indiscriminate use of antibiotics in various fields, including agriculture, should be avoided. Here, we isolated a novel bacteriophage (phage), PCT27, specific for Pectobacterium carotovorum subsp. carotovorum (Pcc), a phytopathogen responsible for soft rot of crops, and investigated its potential as an adjunct to reduce the use of agrochemicals in Pcc control. Phage PCT27, which belongs to the family Autographiviridae, inhibited in vitro growth of Pcc within 1 h of infection by recognizing colanic acid as a host receptor. More than 90% of the virions rapidly adsorbed to the host cells within 3 min, supporting the efficient control of Pcc by PCT27. PCT27 supplementation reduced the minimum inhibitory concentration of streptomycin by 50% for Pcc control in vitro. Accordingly, PCT27 successfully complemented an antibiotic-based agrochemical in preventing Pcc infection in Chinese cabbage leaves and seedlings by reducing the dose of the agrochemical by a quarter. As a biocontrol agent for Pcc that complements agrochemicals, PCT27 can not only prevent economic losses due to crop decay but would also contribute to addressing the AMR crisis for sustainable agriculture and environmental safety.

Chemical Composition, Antibacterial, Antioxidant and Enzyme Inhibitory Activities of the Essential Oil from Leaves of Psidium guajava L.

Guava (Psidium guajava L.) leaf essential oil (GLEO) was extracted by water distillation, and its in vitro antioxidant, antidiabetic, and antibacterial properties were evaluated. Using GC/MS to determine the chemical components of GLEO, 27 constituents were identified, accounting for 74.90 % of the total oil content, among which L-caryophyllene (24.46 %), L-calamenene (10.82 %), (-)-globulol (10.69 %), and α-copaene (8.71 %) were the main components. Subsequently, the antioxidant activity of GLEO was determined by DPPH, ABTS, and β-carotene bleaching tests. The half maximal inhibitory concentration of GLEO for three free radicals were IC50 =17.66±0.07 μg/mL, IC50 =19.28±0.03 μg/mL, and IC50 =3.17±0.01 μg/mL, respectively. Moreover, GLEO exhibited remarkable α-amylase (IC50 =13.99±0.34 μg/mL) and α-glucosidase (IC50 =5.50±1.02 μg/mL) inhibitory activities. It was effective against Streptomyces acidiscabies (MIC=1.25 μg/mL), Ralstonia solanacearum (MIC=5 μg/mL), and Erwinia carotovora subsp carotovora borgey (MIC=2.5 μg/mL), showing significant antibacterial properties. Based on the findings, given the high biological activity of GLEO, it is a biological preservative for food, medicine, and cosmetics and is valuable in natural therapy and crop disease management.

Antibacterial Activity of a Novel Oligosaccharide from Streptomyces californics against Erwinia carotovora subsp. Carotovora.

The present study aims to characterize and predict models for antibacterial activity of a novel oligosaccharide from Streptomyces californics against Erwinia carotovora subsp. carotovora using an adaptive neuro-fuzzy inference system and an artificial neural network. The mathematical predication models were used to determine the optimal conditions to produce oligosaccharide and determine the relationship between the factors (pH, temperature, and time). The characteristics of the purified antibacterial agent were determined using ultraviolet spectroscopy (UV/Vis), infrared spectroscopy (FT-IR), nuclear magnetic resonance spectroscopy (1H- and 13C-NMR), and mass spectrometry (MS). The best performances for the model were 39.45 and 35.16 recorded at epoch 1 for E. carotovora Erw5 and E. carotovora EMCC 1687, respectively. The coefficient (R2) of the training was more than 0.90. The highest antimicrobial production was recorded after 9 days at 25 °C and a pH of 6.2, at which more than 17 mm of the inhibition zone was obtained. The mass spectrum of antimicrobial agent (peak at R.T. = 3.433 of fraction 6) recorded two molecular ion peaks at m/z = 703.70 and m/z = 338.30, corresponding to molecular weights of 703.70 and 338.30 g/mol, respectively. The two molecular ion peaks matched well with the molecular formulas C29H53NO18 and C14H26O9, respectively, which were obtained from the elemental analysis result. A novel oligosaccharide from Streptomyces californics with potential activity against E. carotovora EMCC 1687 and E. carotovora Erw5 was successfully isolated, purified, and characterized.

Development of Diagnosis System for Pectobacterium Carotovorum Subsp. Carotovorum with Loop-Mediated Isothermal Amplification in Agricultural Products

Development of Diagnosis System for Pectobacterium Carotovorum Subsp. Carotovorum with Loop-Mediated Isothermal Amplification in Agricultural Products

DETECTION OF VIRAL AND BACTERIAL INFECTIONS IN ORDER TO OBTAIN HIGH QUALITY INITIAL POTATO SEED MATERIAL

The article presents the research results on the selection of clones free from phytoinfection in original potato seed production. It is necessary to use a number of diagnostic tests that complement each other and allow the detection of a wide range of viral infections such as PVX, PVY, PVS, PVM, PLRV, PVA, TRV, PMTV, AMV, PSTV and bacterioses: Ralstonia solanacearum, Pectobacterium carotovorum subsp. Atrosepticum, Clavibacter michiganensis. Moreover, studies have shown the necessity
 for TRV detection testing when selecting the initial ancestral material for introduction into the in vitro culture.

Superior antibacterial activity against seed-borne plant bacterial disease agents and enhanced physical properties of novel green synthesized nanostructured ZnO using Thymbra spicata plant extract

An easy and eco-friendly approach using Thymbra spicata var. spicata L. (TS) plant extract was developed for the formation of nanostructured ZnO. TS aqueous leaf extract was used for the green synthesis of nanostructured ZnO via the Successive ionic layer adsorption and reaction (SILAR) method. Electron microscope images exhibit the morphological adjustments of the samples with respect to change in TS concentration in the growth solution. The nanostructured ZnO grown by SILAR was observed to be polycrystalline with hexagonal crystal structure. The optical energy bandgap value of the samples varies from 3.21 to 3.09 eV as the content of TS increases from 2.5 to 5.0%. Also, the effect of TS additive to ZnO on electrical properties was investigated. It was determined by Van der Pauw measurements that TS contribution to ZnO significantly increased electrical resistance. In addition, impedance analyzes of the produced films were carried out in the frequency range of 20Hz −1 MHz. Nyquist plots showed the single semicircle for all samples, and the values of capacitance and resistance were calculated. Its antibacterial activities was investigated against economically important Gram-positive (Clavibacter michiganensis subsp. Michiganensis) and negative (Pseudomonas syringae pv. Phaseolicola, Pseudomonas cichorii and Pectobacterium carotovorum subsp. Carotovorum) seed-borne plant bacterial disease agents by using paper disc diffusion assay for the first time. In vitro laboratory screenings of green synthesized nanostructured ZnO have given encouraging results, indicating their potential use in the management of seed-borne bacterial diseases.

Carrier and Vector of Pectobacterium carotovorum subsp. Carotovorum and its Handling Through a Base of Entomopathogenic Fungi in Agave sp.

The presence of the carrier and vector of Pectobacterium carotovorum (Jones) (Enterobacteriaceae) was found in Agave potatorum Zucc. (Asparagaceae) (larvae and adults of Scyphopphorus acupunctatus Gyllenhaal [Coleoptera: Curculionidae], larvae of Drosophila melanogaster Macquart [Diptera: Drosophilidae] and Hermetia illucens [L.] [Diptera: Stratiomyidae], and adults of Hololepta sp. [Coleoptera: Histeridae]) in Oaxaca, Mexico. Entomopathogenic fungi have been used as control methods to prevent the development of bacteria under laboratory conditions. After 5 d of inoculation, all the existing insects in the agave plants exhibited 98% of the countable growth of the bacterium, which led to the determination that the 4 species of insects are carriers and vectors of P. carotovorum. According to the final growth of the bacterium and the entomopathogenic fungi, the Beauveria bassiana (Bals.-Criv.) Vuill. (Cordycipitaceae) (E) strain at a concentration of 1.0 × 104 spores per mL showed a difference of 57.2 mm. For this reason, it was considered the best strain to disable the growth of P. carotovorum. Resumen Se determinaron insectos portadores y vectores de la bacteria Pectobacterium carotovorum presentes en plantas de Agave potatorum Zucc. (larvas y adultos de Scyphopphorus acupunctatus, larvas de Drosophila melanogaster y Hermetia illucens, y adultos de Hololepta sp.), y como metodos de control se utilizaron hongos entomopatogenos para inhibir el desarrollo de la bacteria en condiciones de laboratorio. A los 5 dias de la inoculacion todos los insectos presentes en las plantas de agave presentaron un 98% de crecimiento contable de la bacteria, por lo que se determino que las cuatro especies de insectos son portadores y vectores de P. carotovorum. De acuerdo al crecimiento final de la bacteria y los hongos entomopatogenos, la cepa Beauveria bassiana (E) a una concentracion de 1.0 × 104 esporas por mL presento una diferencia de 57.2 mm por lo que se considera como la mejor cepa que inhibio el crecimiento de P. carotovorum. Key Words: agave weevil; Scyphophorus acupunctatus; Beauveria bassiana; Metarhizum anisopliae View this article in BioOne

Efficacy of Argentinean propolis extracts on control of potato soft rot caused by Erwinia carotovora subsp.

Erwinia carotovora subsp. cause the potato soft rot, which is a major disease in agriculture. Antibacterial agents currently applied on potato soft rot often offer a restricted control and have several disadvantages. Propolis has shown a wide range of antimicrobial activity, although its effect has not been investigated on E. carotovora subsp. In this work, we tested extracts from propolis samples of Northwest Argentina against E. carotovora subsp. Ethanolic propolis extracts (EPEs) from samples of Santiago del Estero province, particularly from sample 4 (EPE4), showed the highest antibacterial activity, which was associated with the highest content of flavonoids. 2',4'-Dihydroxychalcone, 2',4'-dihydroxy-3'-methoxychalcone, galangin, and pinocembrin were identified as antibacterial constituents of EPE4. 2',4'-Dihydroxychalcone showed an antibacterial activity (minimum inhibitory concentration, MIC = 0.3-1.2 μg gallic acid equivalents (GAE) mL-1 ; minimum bactericidal concentration, MBC = 0.6-4.8 μg GAE mL-1 ) lower than that of bacterimycin (MIC = 2.4-9.6 μg mL-1 ; MBC = 19.2-38.4 μg GAE mL-1 ) and streptocycline (MIC = 19.2-38.4 μg mL-1 ; MBC = 38.4-76.8 μg mL-1 ). Preventive assays on unwounded and wounded potatoes showed that their immersion in EPE4 containing 87.5 μg GAE mL-1 or streptocycline containing 40 μg mL-1 was equally effective in controlling potato soft rot, reducing the disease incidence by 64.6-67.0% (unwounded tubers) and 88.0-86.0% (wounded tubers) and the disease severity by 49.8-49.8% (unwounded tubers) and 54.5-68.5% (wounded tubers). Flavonoid-rich propolis extracts from Northwest Argentina efficiently reduced in vivo the incidence and severity of potato soft rot caused by E. carotovora subsp.

Efficacy of potent antagonistic yeast Wickerhamiella versatilis against soft rot disease of potato caused by Pectobacterium carotovorum subsp. carotovorum

In this study, an antagonistic yeast isolate, Wickerhamiella versatilis was considered as a promising biocontrol agent against Pectobacterium carotovorum subsp. Carotovorum (Pcc) the causal agent of soft rot disease of potato. Antagonistic yeast inhibited the growth of Pcc in vitro, and reducing the soft rot severity of infected potato tubers (cv. Diamant) under greenhouse conditions. Consequently, cellulase and pectinase hydrolytic activities in infected potato tubers with yeast + Pcc were decreased compared with infected tubers with Pcc. The histological characterization of treated potato tubers with antagonistic yeast W. versatilis using scanning electron microscope showed the accumulation of extracellular substances that may induce plant resistant and protects potato tubers from hydrolysis and damages. This study may introduce the possibility of using the antagonistic yeast isolate, as a biocontrol agent against soft rot of potato tubers.

Diversity and probiotic activities of endophytic bacteria associated with the coastal halophyte Messerschmidia sibirica

There is an increasing interest for exploitation and utilization of endophyte resources. However, little was known about endophytic bacteria (EB) associations with halophytes. It is hypothesized that EB from halophytes have evolved mechanisms that promote plant growth, while improving host-plant resistance to biotic and abiotic stress. The present study is the first to examine culturable EB colonization in Messerschmidia sibirica, a salt-secreting halophyte grown in coastal zone of Shandong peninsula in China. Total 198 EB strains were isolated from 450 samples of healthy M. sibirica leaf, stem, and root tissues. Phylogenetic analysis of 16S rRNA gene identified 40 EB genera, indicating a high degree of diversity. Pseudomonas alcaliphila had the highest colonization frequency in leaves and roots, whereas Bacillus subtilis was highest in stems. Diversity and species richness were greater in leaves and stems than in roots. Notably, cultivation-independent and -dependent analyses identified different bacterial species, especially when abundance is low, indicating the necessity of combining the two methods. Most (92.39%) strains exhibited at least one plant growth promotion trait. Respectively, 68.69%, 75.25%, 47.98%, 21.21%, and 48.48% of strains exhibited 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity, IAA secretion, siderophore production, and N-fixation, and P-solubilization. In addition, 13.64% of strains showed antimicrobial activity against one or more plant pathogens, including Phytophthora nicotianae, Alternaria alternata, Ralstonia solanacearum, Acidovorax citrulli, Pseudomonas syringae pv. lachrymans, and Erwinia carotovora subsp. Carotovora. Overall, our results supported the habitat-adapted symbiosis hypothesis, demonstrating that M. sibirica naturally harbors a diverse array of EB with different traits beneficial to the host plant.

Variability of Aggressiveness and Virulence of Erwinia carotovora subsp. Carotovorum Causing the Soft Rot on Potato Tubers in the Western of Algeria

Soft rot symptoms were observed on potato plants in several potato cultivars in the western part of Algeria. A total of four strains of Erwinia are devided as follow: (i) three strains of bacteria isolated from diseased tissues and soil, identified as Erwinia carotovora subsp carotovorum using conventional bacteriological and biochemical methods; and (ii) one strain as Erwinia sp, not pathogens. In vitro tests, on tuber slices were set up to determine slices weight lost, which allows to find differences in cultivar susceptibility and isolate aggressiveness. Among the five cultivars, Laura was the most susceptible than the others tested cultivars. Moreover, it was found that MAI isolate was the most virulent than the other bacterial isolates. The results of this study should allow an optimization of the potato storage, after considering the susceptibility of a given cultivar to soft rot development and the aggressiveness.

English

Tomato (Solanum lycopersicum L.) is a species of the family Solanaceae. It is herbaceous, annual to perennial, prostrate and sexually propagated plant with bisexual flower. Tomatoes are attacked by many kinds of plant pathogens such as fungi, bacteria, nematodes, viruses and viroid. Among bacterial diseases, bacterial soft rot devastates many important crops of the family Solanaceae particularly potato, eggplant and tomato, causing a huge decrease in yield and a greater loss in produce than any bacterial disease known. Yield losses due to post-harvest diseases of fruits and vegetables range from 20 to 30% but losses due to soft rot bacteria may reach up to 100% under insufficient conditions of storage facility, this have huge impacts on famers and vendors. In vitro efficacy of certain botanicals against bacterial soft rot of tomato were tested in the months of February to March, 2015 in the Department of Plant Pathology and Department of Biochemistry, Sam Higginbottom Institute of Agriculture, Technology and Sciences (Deemed University)– Allahabad, UP, India. Eight botanicals were screened in vitro, out of these, four were selected based on their performances and evaluated against the bacterial soft rot of storage tomato at 2, 4, and 8 days after inoculation. Maximum zone of inhibition was obtained with treated Control (T0b=17 mm), followed by Turmeric 30% (T4=12.4 mm), Turmeric 20% (T3=11 mm), then Neem 30% (T6) while the least zone of inhibition was recorded with untreated Control/water (T0a=0.4 mm) followed by Lemon 30% (T12=1 mm). Turmeric 30% (T4) proved to be best botanical under screening followed by Turmeric 20% (T3=11mm). In case of mean disease intensity at eight days after inoculation on storage tomato, highest mean value was recorded in Ginger 30% (T2=46.2) followed by Neem 20% (T5=44.2) and lowest value in Streptomycin (T0b=27), followed by Turmeric 20% (T3=27.6) then Turmeric 30% (T4=27.8). Among the botanicals, the lowest disease intensity was with T3=27.6 followed by T4= 27.8. Key words: Tomato, Pectobacterium carotovora subsp carotovora, botanicals, efficacy.

Curcumin from Curcuma longa affects the virulence of Pectobacterium wasabiae and P. carotovorum subsp. carotovorum via quorum sensing regulation

In plant soft-rotting bacteria Pectobacterium, quorum sensing (QS) regulates the secretion of an arsenal of plant cell wall degrading extracellular enzymes (PCWDEs) and flagella-mediated motility via two different signaling molecules such as 3-oxohexanoyl-L-homoserine lactone (3-oxo-C6-AHL) and 3-oxooctanoyl-L-homoserine lactone (3-oxo- C8-AHL). In the present investigation, the phytochemical compound curcumin was assessed for its QS inhibitory potential against AHL-dependent PCWDEs production and motility in P. wasabiae SCC3193, P. carotovorum subsp. Carotovorum Pcc21 and P. carotovorum subsp. Carotovorum Pcc. Interestingly, curcumin at sub-MIC effectively inhibited the production of PCWDEs as well as the swimming and swarming motility of all tested pathogens in a non-bactericidal fashion. Subsequently, the in vitro root pathogenicity assay in Arabidopsis thaliana unveiled the rescuing efficacy of curcumin against the pathogenicity of tested plant pathogens by attenuating its QS mediated virulence factors production. Besides, studies with QS mutant strain Pcc21-M10 also evidenced the QSI property of curcumin.

Phytochemical Determination and Antibacterial Activity of <i>Punica granatum</i> Peel Extracts against Plant Pathogenic Bacteria

Plant pathogenic bacteria are recognized to be harmful microbes able to decrease the quantity and quality of crop production in the world. Punica granatum peel was screened for its potential use as biological control agent for plant pathogenic bacteria. P. granatum peel was successfully extract using n-hexane, methanol and ethyl acetate by maceration. The highest yield obtained by ethyl acetate showed that ethyl acetate extracted more compounds that readily soluble to methanol and n-hexane. For in-vitro antibacterial activity, three different species of plant pathogenic bacteria were used namely Erwinia carotovorum subsp. Carotovorum, Ralstonia solanacearum, and Xanthomonas gardneri. For all crude extracts, four different concentrations 25, 50, 100 and 200 mg/ml were used in cup-plate agar diffusion method. Streptomycin sulfate at concentration 30 μg/ml was used as positive control while each respective solvent used for peel extraction was used as negative control. The results obtained from in vitro studies showed only ethyl acetate extract possessed antibacterial activity tested on the plant pathogenic bacteria. Methanol and n-hexane did not show any antibacterial activity against plant pathogenic bacteria selected where no inhibition zones were recorded. R. solanacearum recorded the highest diameter of inhibition zones for all range of concentrations introduced followed by E. carotovorum subsp. Carotovorum and X. gardneri. For the minimum inhbitory concentration (MIC) and minimum bactericidal concentration (MBC), only the ethyl acetate extract was subjected to the assay as only ethyl acetate extract exhibited antibacterial activity. The minimum concentration of ethyl acetate extract that was able to inhibit plant pathogenic bacteria was recorded at a concentration of 3.12 mg/ml which inhibited R. solancearum and E. carotovorum subsp. Carotovorum, followed by X. gardneri at concentration 6.25 mg/ml. For the minimum bactericidal concentration (MBC), the results showed that at the concentration of 12.5 mg/ml, the extract was still capable of killing the pathogenic bacteria, R. solanacearum, and P. caratovora sub.sp. caratovora while for the bacteria X. gardneri, the concentration that was able to kill the bacteria was 25 mg/ml. The qualitative estimation of phytochemical constituents within P. granatum L. ethyl acetate peel extracts had revealed the presence of tannins, flavonoids, phenols alkaloid, Saponins, and terpenoids. This study has demonstrated that Ethyl Acetate peel extracts of P. granatum has significant antibacterial activity against pathogenic plant bacterial, and it could be of high agricultural value.

Phenotypic and genotypic diversity of Pectobacterium carotovorum subsp carotovorum causing soft rot disease of potatoes in Morocco

The species Pectobacterium carotovorum include a diverse subspecies of bacteria that cause disease on a wide variety of plants. In Morocco, approximately 95 % of the P. carotovorum isolates from potato plants with tuber soft rot are P. carotovorum subsp carotovorum. The aim was to monitor this Moroccan population in time and to continue the work carried out to understand the genetic diversity of these subspecies. The diversity of 30 strains of P. carotovorum subsp carotovorum collected between 2012 and 2013 from potato soft rot from different Moroccan regions was evaluated. On the basis of phenotypic characteristics, the isolates were classified into four different biovars and in three groups based on the aggressiveness traits. Moreover, the genetic variability was also investigated by fingerprint analysis. The typing by ERIC and REP sequences of the new collection compared to ERIC-PCR and phylogenetic analysis of pmrA sequences, demonstrated that there is a considerable genetic diversity in P. carotovorum subsp. carotovorum strains, which can be divided into two distinct groups, independently to their source of isolation, by their pathogenicity.