Agent Of Root Rot Disease Research Articles

Green Synthesized of Thymus vulgaris Chitosan Nanoparticles Induce Relative WRKY-Genes Expression in Solanum lycopersicum against Fusarium solani, the Causal Agent of Root Rot Disease.

Fusarium solani is a plant pathogenic fungus that causes tomato root rot disease and yield losses in tomato production. The current study's main goal is testing the antibacterial efficacy of chitosan nanoparticles loaded with Thyme vulgaris essential oil (ThE-CsNPs) against F. solani in vitro and in vivo. GC-MS analysis was used to determine the chemical constituents of thyme EO. ThE-CsNPs were investigated using transmission electron microscopy before being physicochemically characterized using FT-IR. ThE-CsNPs were tested for antifungal activity against F. solani mycelial growth in vitro. A pot trial was conducted to determine the most effective dose of ThE-CsNPs on the morph/physiological characteristics of Solanum lycopersicum, as well as the severity of fusarium root rot. The relative gene expression of WRKY transcript factors and defense-associated genes were quantified in root tissues under all treatment conditions. In vitro results revealed that ThE-CsNPs (1%) had potent antifungal efficacy against F. solani radial mycelium growth. The expression of three WRKY transcription factors and three tomato defense-related genes was upregulated. Total phenolic, flavonoid content, and antioxidant enzyme activity were all increased. The outfindings of this study strongly suggested the use of ThE-CsNPs in controlling fusarium root rot on tomatoes; however, other experiments remain necessary before they are recommended.

Essential Oil of Foeniculum vulgare Mill. as a Green Fungicide and Defense-Inducing Agent against Fusarium Root Rot Disease in Vicia faba L.

Simple SummaryPlant extracts, including essential oils, are a viable alternative method for controlling plant diseases. This work deals with the exploitation of fennel seed essential oil (FSEO) to inhibit Fusarium solani and control Fusarium root rot disease in Vicai faba. In vitro FSEO inhibited mycelium growth by up to 80% at 400 µL/mL of FSEO. In vivo, the protective effects against Fusarium root rot disease were recorded when FSEO was applied to Vicia faba seeds. The FSEO reduced the disease severity from 98% in plants grown in infested soil with Fusarium solani to 60.1% in plants that previously had their seeds treated with FSEO. GC-MS spectrometry analyses showed that the major chemical components in the essential oil were D-limonene, menthol, estragole and 2-decenal. Applications of the essential oil resulted in increased total phenolic and flavonoid contents in leaves compared with untreated inoculated (control) plants. The defense-related genes, such as defensin and chitinase, were differentially expressed. This study revealed that the essential oil of fennel seed was effective as a control agent against Fusarium root rot in broad beans.Fusarium solani, the causative agent of root rot disease is one of the major constraints of faba bean (Vicia faba L.) yield worldwide. Essential oils have become excellent plant growth stimulators besides their antifungal properties. Foeniculum vulgare Mill. (fennel) is a familiar medicinal plant that has inhibitory effects against phytopathogenic fungi. Herein, different concentrations of fennel seed essential oil (FSEO) (12.5, 25, 50, 100, 200 and 400 μL/mL) were examined against F. solani KHA10 (accession number MW444555) isolated from rotted roots of faba bean in vitro and in vivo. The chemical composition of FSEO, through gas chromatography/mass spectroscopy, revealed 10 major compounds. In vitro, FSEO inhibited F. solani with a minimum inhibitory concentration (MIC) of 25 µL/mL. In vivo, FSEO suppressed Fusarium root rot disease in Vicia faba L. by decreasing the disease severity (61.2%) and disease incidence (50%), and acted as protective agent (32.5%) of Vicia faba L. Improvements in morphological and biochemical parameters were recorded in FSEO-treated faba seeds. Moreover, the expression level of the defense-related genes defensin and chitinase was noticeably enhanced in treated plants. This study suggested using FSEO as a promising antifungal agent against F. solani not only to control root rot disease but also to enhance plant growth and activate plant defense.

The Screening of White-Rot Fungi as Biological Control Agents against Ganoderma philippii

Ganoderma philippii is the causal agent of root rot disease causing economic losses to Acacia plantations. In an effort to control the Ganoderma root-rot disease, we isolated and screened white-rot fungi as biological control agents. We collected 107 samples from forestry plantations in Riau Province. The fungi were isolated from rotten wood including trunks and twigs, and fruiting bodies. Out of the 107 samples, 28 from rotten woods and 51 from fruiting bodies were successfully isolated. Screening of the isolated fungi was done on wood block, wood disc, and wood-powder-containing agar. Eleven isolates showed fast growth on wood block and in subsequent second screening in dual culture on wood disc, three isolates showed fast growth and were capable of overgrowing G. philippii. The third screening was to examine quantitative growth rate of selected fungal isolates on malt extract agar wood powder (MEA-WP) two isolates were selected. These two isolates have shown potential as biological control agents of the root-rot pathogen, G. philippii.

Research Article Detection of sequences related to biosynthesis of antifungal metabolites and identification of a <em>PhzF</em>-like gene in a <em>Pseudomonas rhizobacterium</em> of <em>Piper tuberculatum</em>

Our previous studies identified a Pseudomonas putida (Pt12 isolate) associated with roots of Piper tuberculatum Jacq., a Piperaceae occurring in the Amazon region with known resistance to infection by Fusarium solani f. sp. piperis, the causal agent of root rot disease in black pepper (Piper nigrum L.). This Pt12 isolate was able to inhibit in vitro growth of this fungus 39%. However, the inhibition mechanisms were unknown. Here, we searched for genes coding enzymes involved in the biosynthesis of compounds with potential antifungal activity in the Pt12 isolate, such as phenazine, pyoluteorin, 2,4-diacetylphloroglucinol and hydrogen cyanide. We found sequences potentially related to biosynthesis of phenazine (PhzF) based on DNA sequencing and comparative sequence analyses using the GenBank DataBase. PCR and nested PCR assays were used to isolate a 789-bp sequence coding for a deduced protein with 262 amino acid residues with high identity with a PhzF family phenazine biosynthesis protein from P. putida (WP_046785327.1), P. plecoglossicida (WP_041505738.1) and P. parafulva (WP_039578870.1). Molecular modeling and molecular dynamic simulations revealed that putative PhzF of Pt12 isolate could stably interact with substrate DHHA (Trans-2, 3-dihydro-3- hydroxyanthranilic acid) through some amino acid residues that are similar to conserved amino acids critical to the catalytic activity of a well-characterized PhzF protein produced by Pseudomonas fluorescens.

Beneficial effect of Trichoderma harzianum strain Ths97 in biocontrolling Fusarium solani causal agent of root rot disease in olive trees

Fusarium root rot is a major cryptogamic disease in olive trees caused by the soil-borne fungus Fusarium solani. Controlling this disease requires the extensive use of chemicals. However, using BCAs such as some Trichoderma strains may be an opportune alternative to fungicides in protecting olive plantations. A new isolate (Fso14) was isolated from young olive trees showing severe dieback symptoms. The objective of this work was to analyze the biocontrol behavior of a Tunisian strain of T. harzianum (Ths97) on olive trees against Fso14 by assessing both mycoparasitic activity (in planta and in vitro) and ability to locally modulate different gene-related defenses of the plant. Ths97 was found to inhibit Fso14 growth in vitro. Optical microscopic analysis at the confrontation zone between hyphae showed that Ths97 grew alongside Fso14 with numerous contact points suggesting parasitic activity. On olive trees, Ths97 developed a strong protective role against root infestation by Fso14, whether inoculated before or after the pathogenic agent. When inoculated alone, Fso14 and Ths97 did not modulate (or only slightly with inhibitions or inductions, respectively) the expression of genes involved in plant immunity (oxidative stress, phenylpropanoid pathway, PR-proteins and JA/Et-SA hormonal status). However, when Ths97 was inoculated in combination with Fso14, several defense-related genes were highly up-regulated, indicating probable primed-plant events. These promising results provided valuable information on using Ths97 as a beneficial agent to control fusarium root rot disease caused by F. solani in olive trees.

Cendawan Endofit yang Potensial Meningkatkan Ketahanan Cabai Merah terhadap Penyakit Layu Bakteri

Ralstonia solanacearum has been known to cause bacterial wilt disease on chili pepper. Despite many reports on the potential use of endophytic fungi to induce plant resistance, its utilization to suppress bacterial wilt disease of chili has not been widely reported. The aims of this research was to screen potential endophytic fungi that may increase chili resistance against bacterial wilt disease. Selection of endophytic fungi was done using in vivo and antibiosis test. Strains of fungi were considered the most potent in suppressing the development of bacterial wilt in chilli were identified. Ten out of 62 isolates of endophytic fungi gave the highest suppression on chilli’s bacterial wilt disease. Most strains of endophytic fungi were able to suppress the development of bacterial wilt disease, but not always positively correlated to the vegetative and generative growth of chilli. Based on the level of disease intensity and the growth of plants were obtained three strains of endophytic fungi that considered potentially suppress the incidence of bacterial wilt disease. The three isolates was identified as Fusarium solani f.sp. phaseoli (AC-2.13 and AC-4.4) and Trichoderma asperellum (AC-3.18) using morphology and molecular characters. Although all three selected isolates were able to suppress bacterial wilt disease in this study, but application of F. solani f.sp. phaseoli should be considered in practical use since it is generally known as the causal agent of root rot disease of beans

First Report of Leaf Blight of Eriobotrya japonica Caused by Pestalotiopsis microspora in Anhui Province, China

HomePlant DiseaseVol. 100, No. 5First Report of Leaf Blight of Eriobotrya japonica Caused by Pestalotiopsis microspora in Anhui Province, China PreviousNext DISEASE NOTES OPENOpen Access licenseFirst Report of Leaf Blight of Eriobotrya japonica Caused by Pestalotiopsis microspora in Anhui Province, ChinaS. Xiao, Q. Tang, and K. H. HuangS. XiaoSearch for more papers by this author, Q. TangSearch for more papers by this author, and K. H. HuangSearch for more papers by this authorAffiliationsAuthors and Affiliations S. Xiao , School of Life Sciences, Wuhu Institute of Technology, Wuhu 241003, China, and College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China Q. Tang , School of Life Sciences, Wuhu Institute of Technology, Wuhu 241003, China K. H. Huang , College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China. Published Online:4 Mar 2016https://doi.org/10.1094/PDIS-11-15-1240-PDNAboutSections ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat Loquat, Eriobotrya japonica (Thunb.) Lindl., is an important perennial evergreen fruit crop widely planted and used as an ornamental in Huangshan City, Anhui Province, China. In 2014, leaf blight was observed on 10 to 15% of leaves of loquat planted in Huangshan City. Typical symptoms included spots that were initially small, brown, and oval to irregular. The spots gradually expanded and finally coalesced until the leaf became brown and blighted. Heavily infected leaves became dry and died. To isolate potential pathogens from infected leaves, small sections of leaf tissues (4 mm2) were excised from lesion margins, sterilized in 1.5% sodium hypochlorite for 20 s, rinsed three times with sterile water, dried on sterilized filter paper, and plated on potato dextrose agar (PDA) amended with streptomycin sulfate (0.1 g/liter), plates were incubated at 25°C in the dark. Twenty-one isolates were obtained from leaf lesions, and a representative isolate, HS-16, was characterized further. After 5 days of growing on PDA at 25°C, the fungus produced circular, white colonies. After 10 days, black acervuli containing slimy spore masses formed over the matted mycelium. Conidia were straight or slightly curved, fusiform to clavate, five-celled with constrictions at the septa, and 17.4 to 28.5 × 5.3 to 7.2 μm. Two to four 16.2- to 24.2-μm-long, hyaline, filamentous appendages (mostly three) were attached to each apical cell, whereas one 4.7- to 6.9-μm-long hyaline appendage was attached to each basal cell, matching the description for Pestalotiopsis microspora (Ge et al. 2009). Isolate HS-16 was selected for molecular identification by amplification and sequencing of the ribosomal DNA internal transcribed spacer (rDNA-ITS) using the universal primer pair ITS4 and ITS5. Sequencing of the PCR product revealed a 100% similarity with the ITS sequences of P. microspora in GenBank. The sequence of isolate HS-16 was deposited in GenBank (Accession Nos. KT965676). The morphological characteristics and molecular data in this study corresponded with the fungus P. microspora. The pathogenicity of isolate HS-16 was tested using potted, 3-year-old E. japonica under greenhouse conditions (24 to 28°C). Fifteen plants were inoculated by spraying the leaves with a conidial suspension (1×105 conidia/ml; 50 ml on each plant) cultured for 12 days on PDA. As a control, 15 plants were inoculated with sterilized water. The plants were covered with plastic bags for 3 days to maintain high relative humidity (Zhang et al. 2010). At 30 days after inoculation, small dark lesions enlarged into brown blight similar to that observed on naturally infected leaves. Pestalotiopsis microspora was reisolated from all pathogen-inoculated plants, but not from the control. Pestalotiopsis microspora has been reported as the causal agent of root rot disease on loquat in Guizhou of China (Lu et al. 2015). To our knowledge, this is the first report of P. microspora as a pathogen on E. japonica in Anhui Province, China.

Characterization of alkaline protease produced by Streptomyces griseorubens E44G and its possibility for controlling Rhizoctonia root rot disease of corn

The antifungal activity of Streptomyces griseorubens E44G against Rhizoctonia solani, the causal agent of root rot disease of corn, was investigated. The mycelial growth of R. solani was inhibited by S. griseorubens E44G, indicating that it has an antifungal potential. The antagonist, S. griseorubens E44G, was detected to have proteolytic activity, using the method of casein hydrolysis. Moreover, the protease production was optimized under submerged conditions. The purification and precipitation of protease were achieved by ammonium sulphate and Sephadex G-100 gel filtration chromatography. Protease activity was detected spectrophotometrically based on the production of tyrosine. The molecular weight of the enzyme (35 kDa) was determined by sodium dodecyl sulphate polyacrylamide gel electrophoresis . The optimum activity of the enzyme was detected at pH 8.5 and 60 °C. The results indicated that the enzyme was thermostable and retained full activity even after 1 hour of incubation at 60 °C. The purified enzyme substantially inhibited the growth of R. solani, indicating that this enzyme may be actually involved in the antagonistic process.

Endophytic bacteria from Piper tuberculatum Jacq.: isolation, molecular characterization, and in vitro screening for the control of Fusarium solani f. sp piperis, the causal agent of root rot disease in black pepper (Piper nigrum L.).

Endophytic bacteria have been found to colonize internal tissues in many different plants, where they can have several beneficial effects, including defense against pathogens. In this study, we aimed to identify endophytic bacteria associated with roots of the tropical piperaceae Piper tuberculatum, which is known for its resistance to infection by Fusarium solani f. sp piperis, the causal agent of black pepper (Piper nigrum) root rot disease in the Amazon region. Based on 16S rRNA gene sequence analysis, we isolated endophytes belonging to 13 genera: Bacillus, Paenibacillus, Pseudomonas, Enterobacter, Rhizobium, Sinorhizobium, Agrobacterium, Ralstonia, Serratia, Cupriavidus, Mitsuaria, Pantoea, and Staphylococcus. The results showed that 56.52% of isolates were associated with the phylum Proteobacteria, which comprised α, β, and γ classes. Other bacteria were related to the phylum Firmicutes, including Bacillus, which was the most abundant genus among all isolates. Antagonistic assays revealed that Pt12 and Pt13 isolates, identified as Pseudomonas putida and Pseudomonas sp, respectively, were able to inhibit F. solani f. sp piperis growth in vitro. We describe, for the first time, the molecular identification of 23 endophytic bacteria from P. tuberculatum, among which two Pseudomonas species have the potential to control the pathogen responsible for root rot disease in black pepper in the Amazon region.

Detection and Cloning of a Gene Involved in Zwitermicin A Synthesis from Plant Growth Promoting Rhizobacteria of Bacillus sp CR64

Utilization of soil bacteria as biocontrol agent is becoming popular due to its valuable and effective mechanisms to suppress plant pathogenic microbes. We have previously isolated Bacillus sp, designated as Bacillus sp CR64, which exhibited effective plant growth promoting and antifungal activities. In this study, CR64 was examined in inhibiting the growth of Rhizoctonia solani, the causing agent of root rot disease. Partial sequence analysis of 16S rRNA gene revealed that this isolate similar with Bacillus cereus (94%). Furthermore, a gene designated zmaR was detected by means of specific amplification of DNA fragment approximately 950 bp. This fragment was then cloned onto pCRII-TOPO (3.9 kb) and sequenced using DNA sequencer ABI PRISM 310. Sequence analysis revealed that it had highest homology with the ZmaR protein (89% identity; 90% similarity) of B. thuringiensis serovar kurstaki (AAF82729.2). Alignment analysis with other ZmaR sequences from other antibiotic-producing Bacilli exhibited an almost fully conserved region within ZmaR sequences. Key words : PGPR, Bacillus sp CR64, Zwitermicin A, Cloning, Antifungal.

Characterization of Phytophthora clandestina races on Trifolium subterraneum in Western Australia

Phytophthora clandestina is a causal agent of root rot disease of subterranean clover in Western Australia (W.A). As a significant number of isolates of P. clandestina from W.A. could not previously be designated using existing differentials, a comprehensive set of subterranean clover (Trifolium subterraneum) cultivars was used as differentials to delineate a broader range of races of the pathogen. One hundred and one isolates of the pathogen collected from W.A. were screened on nine subterranean clover cultivars, of which seven were found to be useful as host differentials. A total of 10 races (in contrast to the five recognized previously) were defined and differentiated using octal nomenclature, presenting a clearer picture of the racial distribution of P. clandestina among W.A. isolates. Differences were found in the race populations between Australian states and are therefore important to the selection/breeding of cultivars for specific regions of Australia to counter the predominant race populations and for enforcing quarantine measures in relation to seed movements within and outside Australia. The octal nomenclature used provides a sound basis for follow-up studies and future race designations. Races 173 and 177 in this study were widely distributed and were the most common races in W.A., and together constitute 80% of the isolates characterized. While six of the seven host differentials were resistant to isolates belonging to race 001 and all were resistant to 000, it is of concern that only one differential was resistant to 157 and 173 and that none of the host differentials were resistant to 177. Our approach to P. clandestina race delineation is clearly conservative and is different from previous studies. The octal nomenclature we applied in this study is not only scientifically sound but also will facilitate rapid recognition and characterization of the races.

Biological Control of Fusarium Oxysporum f. sp. Melonis, the Causal Agent of Root Rot Disease of Greenhouse Cucurbits in Kerman Province of Iran

Antagonistic activity of 178 soil actinomycete isolates was assayed against Fusarium oxysporum f. sp. melonis Schlecht, Emend (Snyde and Hansen) cause of root rot and fusarium wilt of greenhouse cucurbits in Kerman Province, southeast of Iran. From tested isolates, Streptomyces olivaceus (strain 115) showed anti-fusarium activity revealed through screening and bioassays by agar disk and well-diffusion methods. The active strain was grown in submerged cultures for determination of growth curve and preparation of crude extract for further biological characterizations. Antifungal activity was fungistatic type on the pathogen mycelia. It is prominent that amending greenhouse soil mix with the S. olivaceus (strain 115) will reduce crop losses by the pathogen.

Probing crucial metabolic pathways in fungal pathogens of crucifers: biotransformation of indole-3-acetaldoxime, 4-hydroxyphenylacetaldoxime, and their metabolites

Indole-3-acetaldoxime is an intermediate of crucial importance in the biosynthesis of diverse plant secondary metabolites of Cruciferae. The metabolism of indole-3-acetaldoxime to indole-3-acetic acid via indole-3-acetonitrile by fungi that cause important plant diseases in crucifers, Leptosphaeria maculans (asexual stage Phoma lingam) causative agent of blackleg disease, Rhizoctonia solani causative agent of root rot disease, and Sclerotinia sclerotiorum causative agent of stem rot disease, is described. As well, the antifungal activity of indole-3-acetaldoxime and metabolites and the synthesis and biotransformation of 4-hydroxyphenylacetaldoxime by the same plant pathogens and by an insect fungal pathogen, Beauveria bassiana, are reported.