Falcaria vulgaris extract: A mixture of quorum sensing inhibitors for controlling Pectobacterium carotovorum subsp. carotovorum.

A promising strategy to control bacterial diseases involves using Quorum Sensing Inhibitor (QSI) compounds. This study aimed to evaluate the potential of Falcaria vulgaris plant extract to combat the phytopathogenic Pectobacterium carotovorum subsp. carotovorum (Pcc) via its QSI activity. Using biosensors and Minimum Inhibitory Concentration (MIC) assays, the QSI and antimicrobial aspects of the extract were assessed. Furthermore, the effect of the extract on the reduction of tuber maceration in potatoes was examined. Subsequently, homology modeling based on LasR was conducted to analyze interactions between ligand 3-oxo-C8-AHL, and ExpR2 protein. Docking studies were performed on all extract compounds identified via Gas Chromatography-Mass Spectrometry (GC-MS) analysis. The extract effectively reduced maceration at sub-MIC concentrations across various pathogenic strains. Furthermore, Cyclopentadecanone, 2-hydroxy, showed more negative docking energy than the native ligand. Z,E-2,13-Octadecadien-1-ol showed energy equivalence to the native ligand. Additionally, this plant included certain compounds or their analogs that had previously been discovered as QSI compounds. These compounds included oleic acid, n-Hexadecanoic acid, cytidine, and linoleic acid, and they had energies that were comparable to that of the native ligand. In conclusion, the remarkable QSI property showed by this plant is likely attributed to a combination of compounds possessing this characteristic.

First report of Verticillium wilt caused by Verticillium dahliae on Russian olive (Elaeagnus angustifolia) in Iran.

Russian olive, also known as, Persian olive or oleaster (Elaeagnus angustifolia L.) is a species in the Elaeagnaceae family native to western and central Asia. In some orchards in Iran, intercropping Russian olive or Prunus trees with vegetables is a common practice. In 2018, about 130 ha of E. angustifolia orchards in Shahrood, Semnan Province, Iran showed branch wilting and dieback. Symptoms on affected trees started with yellowing of the lower leaves, followed by wilting and finally death of affected branches. Sections of stems indicated brown or black streaks in the vascular tissues under the bark. Isolations were made from discolored vascular tissues by surface-disinfesting small pieces of tissue with 0.5% sodium hypochlorite for 2 min, plating them onto potato dextrose agar amended with 25 mg/l streptomycin sulfate and incubated in the dark for 14 days at 25°C. Fungi consistently isolated from symptomatic tissues. Fungal isolates were identified as Verticillium dahliae Kleb. based on characteristics of verticillate conidiophores, hyaline, elliptical, single celled conidia measuring 4.7-6.0 × 2.3-3.4 µm (n = 100) and irregular, dark microsclerotia measuring 27-34 × 22-26 µm (n = 50) that developed after 14 days of growth at 25°C in the dark. The identification of two isolates was further confirmed by performing real-time PCR assay using a pair of specific primers for internal transcribed spacer (ITS) region of V. dahliae as previously described (Hiemstra et al. 2013). In addition, the molecular subdivision of isolates was further determined to discriminate D and ND molecular types (Keykhasaber 2017). According to molecular assays, isolates were identified as V. dahliae and grouped with ND types. The pathogenicity of isolates was evaluated by root-dipping one-year E. angustifolia seedlings (10 seedlings) into conidial suspensions of 1×107 cfu/ml. Inoculated plants were transplanted in pots containing autoclaved soil and maintained in a greenhouse at 25°C until symptoms appearance. Two seedlings were treated with sterile distilled water as controls. All inoculated seedlings started to show wilting symptoms similar to those present in naturally affected trees within 30 days after inoculation and died thereafter. Furthermore, V. dahliae was consistently isolated from symptomatic tissues. No symptoms were observed on the control plants. The pathogenicity test was repeated twice with similar results. To the best of our knowledge, this is the first report of Verticillium wilt on Russian olive trees in Iran. In Iran, Verticillium wilt is the cause of serious losses in many woody and herbaceous plants with economic importance including many trees belonging to the genus Prunus that are highly susceptible to the disease. In Shahrood (Semnan Province), most agricultural fields have a potato- or tomato- growing history. Verticillium wilt may become an important economic problem in many Russian olive and Prunus orchards in the future since their cultivation is expanding rapidly in many agricultural areas previously dedicated to tomato and potato crops, the majority of which are infested with V. dahliae. References Hiemstra, J. A., Korthals, G. W., Visser, J. H. M., Dalfsen, P. v., Sluis, B. J. v. d., and Smits, A. P. 2013. Control of Verticillium in tree nurseries through biological soil disinfestation. Pages 62-62 in: 11th International Verticillium Symposium, Georg-August-Universität,Göttingen, Germany, 5-8 May 2013, B. Koopmann and A. von Tiedemann, eds. DPG Spectrum Phytomedizin, Göttingen. Keykhasaber, M., Faino L., van den Berg, G.C.M., Hiemstra, J. A., Thomma, B. P. H. J. 2017. A robust method for discriminating defoliating and the non-defoliating pathotypes of V. dahliae. . In; Keykhasaber M. thesis 62-84. Sun, M., and Lin, Q. 2010. A revision of Elaeagnus L. (Elaeagnaceae) in mainland China. J. Systematics and Evolution 48:356-390.

Comparative study of antimicrobial activity between some medicine plants and recombinant Lactoferrin peptide against some pathogens of cultivated button mushroom.

The adverse effects of chemical pesticides on human health and environment cannot be ignored, hence it seems that novel alternative compounds should be applied to control plant pathogens. Among various alternative sources, natural compounds such as plant essential oils, plant extracts and recombinant antimicrobial peptides are of significance. The aim of the present study was to investigate antimicrobial activity of plants essential oils and plant extracts of six medicinal plants (Lippia citriodora, Ferula gummosa, Bunium persicum, Mentha piperita, Plantago major and Salvadora persica) along with a chimera peptide of camel lactoferrin, which is the most important antimicrobial component of camel milk, against Pseudomonas tolaasii and Trichoderma harzianum as pathogens of white button mushroom. The antibacterial activity test was conducted under in vitro conditions through disc diffusion method. The results showed that chimera camel lactoferrin peptide, with the highest amount of inhibitory zone (14.63 mm in 20 µg/mL concentration), has a significant difference in antibacterial activity compared to other treatments. Ferula gummosa conferred no antibacterial activity. Also, the results of antifungal effects indicated that plant essential oils and extracts have more antifungal activity than recombinant peptide. Generally, L. citriodora, B. persicum, M. piperita treatments could completely prevent growth of fungal in in vitro conditions. Therefore, using the mentioned plants can be a good replacement for reducing the chemical pesticides against pathogenic agents of button mushroom, without any adverse effects on environment and human health.

Biosynthesis and antibiotic activity of silver nanoparticles using different sources: Glass industrial sewage-adapted Bacillus sp. and herbaceous Amaranthus sp.

Synergistic effects of metallic nanoparticles (NPs) with commonly used antibiotics have encouraged the exploration of novel biological entities, including bacteria and weed plants. The present study for the first time reports the capability of an extracellular fraction of Bacillus sp. isolated from effluents of a glass-manufacturing unit to biosynthesis silver nanoparticles (AgNPs) without hazardous materials. Besides, the biosynthesis of AgNPs using an aqueous extract of herbaceous weed plant (Amaranthus sp.), as a low-cost natural source, has been addressed in this study. Our findings confirmed the fabrication of microbial and plant-sourced AgNPs, being thoroughly characterized by UV-vis, transmission electron microscopy, X-ray diffraction, dynamic light scattering, energy dispersive X-ray spectroscopy, and zeta potential measurements. Further, biological activities of the plant- and bacterium-derived AgNPs were investigated against several pathogenic bacteria, in combination with streptomycin. The antibacterial effectiveness of the antibiotic coated with 400 µg/disk of AgNPs increased over 50% toward all the pathogenic bacteria. The data presented here demonstrate that both industrial wastewater-adapted Bacillus sp. and wild-growing Amaranthus sp. are efficient natural sources with excellent capabilities for creating biologically active AgNPs, which would be of considerable interest for circumventing bacterial resistance to current antibiotics.