63 research outputs found
Detection and characterization of phytoplasmas infecting five plant species in Egypt
No full textSamples of orange, hibiscus, peach, olive and pepper plants showing symptoms of dwarf branches with shortened internodes,
leaf deformation and chlorosis, proliferation of axillary buds, yellowing, twisting and streaks together with samples from
asymptomatic plants of the same age were collected from El-Behira and Alexandria Governorates, Egypt during 2015-2016.
The samples were tested to verify phytoplasma presence by nested PCR assays using the ribosomal gene amplifying primers
R16F2n/R2 on the P1/P7 1: 30 diluted amplicons as template. Amplification bands were obtained only from samples collected
from symptomatic plants, and the RFLP analyses with informative restriction enzymes indicated that detected phytoplasmas
belonged to 16SrII-D subgroup. These phytoplasmas are reported for the first time to infect olive trees, and for the first time
in Egypt in peach, orange and hibiscus plants
Effectiveness of root-bark extract from Salvadora persica against the growth of certain molecularly identified pathogenic bacteria
No full textThe acetone extract from root-bark of Salvadora persica L. (Salvadoraceae), is assayed for its antibacterial activity
against some bacterial pathogens. By GC/MS analysis, the main chemical components of the acetone extract
were found to be benzylisothiocyanate (39.4%), and benzyl nitrile (benzeneacetonitrile) (37.9%). According the
extract concentrations used, the measured inhibition zones observed were between from 13.6 to 18.6 mm,
15.3–23 mm, 13.3–18.3 mm, 13.3–18.3 mm, and 12.3–19 mm, against the isolated plant bacterial pathogens
namely Agrobacterium tumefaciens, Pectobacterium atrosepticum, Enterobacter cloacae, Dickeya solani and Ralstonia
solanacearum, respectively, whilst it was between 8 and 12 mm, 8–9.6 mm, 8–11.6 mm, and 8–10.3 mm against
Bacillus subtilis, Sarcina lutea, Escherichia coli and Staphylococcus aureus, respectively. The minimum inhibitory
concentration values of the extract were between 16 and 32 μg/mL against the growth of plant bacterial, and
from 1000 to 2000 μg/mL against the growth of the human bacteria. In conclusion, the acetone extract of rootbark
of S. persica showed strong antibacterial activity against the plant pathogens and some activity against the
human pathogens were reported. The results suggested that using the acetone extract from root-bark of S. persica
as bioactive agent against the growth of the studied plant bacterial pathogens
Bacillus velezensis PEA1 Inhibits Fusarium oxysporum Growth and Induces Systemic Resistance to Cucumber Mosaic Virus
No full textBacillus velezensis manifests robust biocontrol activity against fungal plant pathogens; however, its antiviral activity has rarely been investigated. Bacillus velezensis strain PEA1 was isolated, characterized, and evaluated for antifungal and antiviral activities against Fusarium oxysporum MT270445 and cucumber mosaic virus (CMV) MN594112. Our findings proved that strain PEA1 had intense antagonist activity against F.oxysporum. Under greenhouse conditions, the antiviral activities (protective, curative, and inactivation) of PEA1-culture filtrate (CF) on Datura stramonium plants were assayed, using a half-leaf method. The inactivation treatment exhibited the highest inhibition rate (97.56%) and the most considerable reduction of CMV-CP accumulation levels (2.1-fold) in PEA1-CF-treated plants when compared with untreated plants (26.9-fold). Furthermore, PEA1-CF induced systemic resistance with significantly elevated transcriptional levels of PAL, CHS, HQT, PR-1, and POD genes in D. stramonium leaves after all treatments. Gas chromatography‒mass spectrometry analysis showed that pyrrolo[1,2-a]pyrazine-1,4-dione is the main compound in the PEA1-CF ethyl acetate extract, which may act as an elicitor molecule that induces plant systemic resistance and inhibits both fungal growth and viral replication. Consequently, B. velezensis can be considered as a potential source for the production of bioactive compounds for the management of plant diseases. To our knowledge, this is the first report of the antiviral activity of B. velezensis against plant viral infection
Rhizobium leguminosarum bv. viciae-Mediated Silver Nanoparticles for Controlling Bean Yellow Mosaic Virus (BYMV) Infection in Faba Bean Plants
No full textThe faba bean plant (Vicia faba L.) is one of the world’s most important legume crops and can be infected with various viral diseases that affect its production. One of the more significant viruses in terms of economic impact is bean yellow mosaic virus (BYMV). The current study used the molecularly identified Rhizobium leguminosarum bv. viciae strain 33504-Borg1, a nitrogen-fixing bacteria, to biosynthesize silver nanoparticles (AgNPs) to control BYMV disease in faba bean plants. Scanning electron microscopy (SEM), a particle size analyzer (PSA) with dynamic light scattering (DLS), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), and Fourier transform infrared spectroscopy (FTIR) were used to characterize the prepared AgNPs. The DLS, SEM, and TEM analyses revealed that the AgNPs were spherical and rough, with sizes ranging from 13.7 to 40 nm. The FTIR analysis recognized various functional groups related to AgNP capping and stability. Under greenhouse conditions, spraying faba bean leaves with the AgNPs (100 µg/mL) 24 h before BYMV inoculation induced plant resistance and reduced plant disease severity and virus concentration levels. Contrarily, the AgNP treatment enhanced plant health by raising photosynthetic rates, increasing the fresh and dry weight of the faba bean plants, and increasing other measured metrics to levels comparable to healthy controls. Antioxidant enzymes (peroxidase and polyphenol oxidase) inhibited the development of BYMV in the faba bean plants treated with the AgNPs. The AgNPs decreased oxidative stress markers (H2O2 and MDA) in the faba bean plants. The plants treated with the AgNPs showed higher expression levels of PR-1 and HQT than the control plants. The study findings could be used to develop a simple, low-cost, and environmentally friendly method of protecting the faba bean plant from BYMV
Antigenic and pathogenicity activities of Ralstonia solanacearum race 3 biovar 2 molecularly identified and detected by indirect ELISA using polyclonal antibodies generated in rabbits
No full textThe efficiency of the antiserum was compared among 42 isolates that cause potato brown rot disease; our polyclonal antiserum (14 days) reacted positively with all tested isolates at a dilution of 1:6.4×103. Data indicated the different reactions of eight R. solanacearum isolates at various dilutions (1:1.6×103 to 1:5.12×106) at 14 days against polyclonal antiserumat a concentration of approximately 1×108 CFU/mL and we found the lowest detection level by the indirect ELISA technique was 106 CFU/mL. Finally we recommended the reasonable sensitivity results of the ELISA technique to detect the bacterial pathogen given than the cost of this technique if much lower than that of other expensive molecular techniques.Eight molecular-characterized isolates of Ralstonia solanacearum from potato belonging to race 3 biovar 2, their virulence were evaluated on potato cv. Lady Rosette, tomato cv. Strain B, eggplant cv. Balady and pepper cv. Balady and showed high virulence on potato and tomato, and lower virulence on eggplant and pepper. A laboratory study conducted to produce polyclonal antibodies against the potato brown rot bacterium; R. solanacearum cells were generated in female New Zealand white rabbits. A modification were made on the technique of indirect enzyme-linked immunosorbent assay (ELISA) to improve the sensitivity of detection, including antigenic and sensitivity to R. solanacearum race 3 biovar 2 isolates. Determination of the optimum period to collect the antiserum (including, polyclonal antibodies) showed that the best collection dates were at 14, 3 and 7 days, in that order
Comparative Analysis of the Expression Profiles of Pathogenesis-Related Genes in Tomato Systemically Infected with Tobacco Mosaic and Cucumber Mosaic Viruses
No full textIn this study, we used RT-qPCR to examine how PR genes were expressed in model tomato (Solanum lycopersicum L.) plants that had been infected with TMV or CMV. Under greenhouse conditions, the indirect ELISA data showed that both viruses were detected for the first time at 6 dpi. Then, the levels of accumulation increased very quickly, reaching a peak of 15 dpi. During the course of the study (1–15 dpi), the Delta CT, NormFinder, BestKeeper, and GeNorm software tools revealed that the β-actin gene was the most informative reference gene in the virally infected tomato tissues. For both the TMV- and CMV-infected tomato plants, the transcriptional expression levels of most tested genes changed between activation and repression, especially in the first 12 dpi. Compared to mock-inoculated plants, the expression levels of PR-1 were induced at all time intervals except at 8 dpi for CMV and at 6, 7, and 8 dpi for TMV infection. Conversely, the greater activation and accumulation of both viruses were associated with the greater up-regulation of PR-2 at 8 dpi, with relative expression levels of 7.28- and 5.84-fold for TMV and CMV, respectively. The up-regulated expression of PR-3, PR-4, and PR-7 was shown at 4 dpi. In contrast, the PR-5 gene was inhibited in TMV at 1 dpi until 9 dpi, and the induction of this gene at 10 dpi increased by 1.72-fold, but PR-5 was observed to up-regulate the expression of CMV at 1 dpi. This study provides the first valuable information on the comparative transcriptional levels of these tomato genes between TMV and CMV infections
Protective and Curative Effects of Trichoderma asperelloides Ta41 on Tomato Root Rot Caused by Rhizoctonia solani Rs33
No full textTwo molecularly identified tomato isolates, Trichoderma asperelloides Ta41 and Rhizoctonia solani Rs33, were characterized and antagonistically evaluated. The dual culture technique showed that Ta41 had a high antagonistic activity of 83.33%, while a light microscope bioassay demonstrated that the Ta41 isolate over-parasitized the pathogen completely. Under greenhouse conditions, the application of Ta41 was able to promote tomato plant growth and had a significant increase in plant height, root length, and shoot fresh, shoot dry, root fresh, and root dry weight. It also improved chlorophyll content and total phenol content significantly, both in protective and in curative treatments. The protective treatment assay exhibited the lowest disease index (16.00%), while the curative treatment showed a disease index of 33.33%. At 20 days post-inoculation, significant increases in the relative expression levels of four defense-related genes (PR-1, PR-2, PR-3, and CHS) were observed in all Ta41-treated plants when compared with the non-treated plants. Interestingly, the plants treated with Ta41 alone showed the highest expression, with relative transcriptional levels of CHS, PR-3, PR-1, and PR-2 that were, compared with the control, 3.91-, 3.13-, 2.94-, and 2.69-fold higher, respectively, and the protective treatment showed relative transcriptional levels that were 3.50-, 3.63-, 2.39-, and 2.27-fold higher, respectively. Consequently, the ability of Ta41 to promote tomato growth, suppress Rs33 growth, and induce systemic resistance supports the incorporation of Ta41 as a potential bioagent for controlling root rot disease and increasing the productivity of crops, including tomatoes
The Phytochemical, Antifungal, and First Report of the Antiviral Properties of Egyptian Haplophyllum tuberculatum Extract
No full textIn this study, ethanol whole plant extract (WPE) of Haplophyllum tuberculatum was characterized and tested for its antifungal and antiviral activities against Fusarium culmorum, Rhizoctonia solani and tobacco mosaic virus (TMV). High Performance Liquid Chromatography (HPLC) analysis showed that the main phytochemical constituents of H. tuberculatum WPE were resveratrol (5178.58 mg/kg), kaempferol (1735.23 mg/kg), myricetin (561.18 mg/kg), rutin (487.04 mg/kg), quercetin (401.04 mg/kg), and rosmarinic acid (387.33 mg/kg). By increasing H. tuberculatum WPE at concentrations of 1%, 2%, and 3%, all of the fungal isolates were suppressed compared to the two positive and negative controls. Under greenhouse conditions, WPE-treated Chenopodium amaranticolor plants strongly inhibited TMV infection and significantly reduced TMV accumulation levels when compared to non-treated plants. Moreover, the induction of systemic resistance with significant increases in the transcriptional levels of the pathogenesis-related protein-1 (PR-1), chalcone synthase (CHS), and hydroxycinnamoyl-CoA quinate transferase (HQT) genes for treated plants were noticed at 3 and 5 days post-inoculation (dpi) for both assays. To the best of our knowledge, this is the first reported observation of the antiviral activity of H. tuberculatum extract against plant viral infections. Finally, the results obtained suggest that H. tuberculatum WPE can be considered a promising source of both antifungal and antiviral substances for practical use and for developing plant-derived compounds for the effective management of plant diseases
HPLC and GC–MS analyses of phytochemical compounds in Haloxylon salicornicum extract: Antibacterial and antifungal activity assessment of phytopathogens
No full textThe present study investigated the phytochemical constituents and antimicrobial effects of aqueous methanolic extract of Haloxylon salicornicum against some phytopathogenic bacterial and fungal strains. The selected bacterial strains were Pectobacterium carotovorum, Pectobacterium atrosepticum, Ralstonia solanacearum, and Streptomyces scabiei, while fungal strains were Fusarium oxysporum, Botrytis cinerea, and Rhizoctonia solani. The extract demonstrated significant efficacy against P. atrosepticum and P. carotovorum at a concentration of 1,000 µg/mL, resulting in inhibition zones measuring 12.3 and 11 mm, respectively. Furthermore, the extract demonstrated considerable effectiveness against fungal strains, achieving an impressive fungal growth suppression rate of 68.8% against R. solani at a concentration of 5,000 µg/mL. The high-performance liquid chromatography analysis identified nine notable phenolic compounds and six common flavonoid compounds in the extract. The identified phenolic compounds in the highest quantities were gallic acid (6427.5 µg/g), vanillin (1145.4 µg/g), chlorogenic acid (498.1 µg/g), and syringic acid (322.5 µg/g). Apigenin (1155.9 µg/g), daidzein (460.9 µg/g), quercetin (382.7 µg/g), and naringenin (160.4 µg/g) exhibited the most significant concentrations of flavonoid compounds. Gas chromatography–mass spectrometry analysis revealed that n-hexadecanoic acid (53.7%), 9-octadecenoic acid (26.9%), 9,12-octadecadienoic acid (Z,Z) (8.67%), palmitic acid, and TMS derivative (4.36%) were the predominant compounds in the extract. Consequently, the H. salicornicum aqueous methanolic extract could be used for the first time as an environmentally safe antimicrobial pesticide agent against plant pathogens to reduce the excessive use of chemical pesticides
The Potential Antibacterial and Antifungal Activities of Wood Treated with Withania somnifera Fruit Extract, and the Phenolic, Caffeine, and Flavonoid Composition of the Extract According to HPLC
No full textIn the present study, Melia azedarach wood blocks treated with different acetone extract concentrations from Withania somnifera fruits are assessed for their antibacterial and anti-fungal activities. Wood blocks of M. azedarach treated with W. somnifera fruit extract at concentrations of 0, 1, 2, and 3% are evaluated for in vitro antimicrobial activity against five genbank accessioned bacterial strains—Agrobacterium tumefaciens, Dickeya solani, Erwinia amylovora, Pseudomonas cichorii, and Serratia pylumthica—and two fungi, namely, Fusarium culmorum and Rhizoctonia solani. Through HPLC analysis we find that the most abundant quantified phenolic and flavonoid compounds of acetone extract (mg/100 g) are salicylic acid (9.49), vanillic acid (4.78), rutin (4702.58), and myricetin (1386.62). Wood treated with the extract at 2% and 3% show no growth of A. tumefaciens, E. amylovora, and P. cichorii. Use of the extract at 3% causes inhibition of fungal mycelia of F. culmorum and R. solani by 84.07% and 67.03%, respectively. In conclusion, potent antifungal and antibacterial activity against plant pathogens is found when an acetone extract of W. somnifera fruits is applied to wood samples
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