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1.
Pseudomonas fluorescens strains CHA0 and Pf1 were investigated for their biocontrol efficacy against Banana bunchy top virus (BBTV) in banana (Musa spp.) alone and in combination with chitin under glasshouse and field conditions. Bioformulation of P. fluorescens strain CHA0 with chitin was effective in reducing the banana bunchy top disease (BBTD) incidence in banana under glasshouse and field conditions. In addition to disease control, the bioformulation increased the economic yield significantly compared to the untreated control. Increased accumulation of oxidative enzymes, peroxidase (PO), polyphenol oxidase (PPO), phenylalanine ammonia lyase (PAL), pathogenesis-related (PR) proteins, chitinase, β-1,3-glucanase and phenolics were observed in CHA0 bioformulation amended with chitin-treated plants challenged with BBTV under glasshouse conditions. Indirect ELISA indicated the reduction in viral antigen concentration in P. fluorescens strain CHA0 with chitin-treated banana plants corresponding to reduced disease ratings. The present study revealed that induction of defence enzymes by P. fluorescens with chitin amendment reduced the BBTD incidence and increased bunch yield in banana.  相似文献   

2.
BACKGROUND: The biological control of plant pests and diseases using a single organism has been reported to give inconsistent and poor performance. To improve the efficacy, bioformulations were developed possessing mixtures of bioagents. RESULTS: Bioformulations combining Pseudomonas fluorescens Migula strains Pf1 and AH1 and Beauveria bassiana (Balsamo) Vuill. isolate B2 were developed and tested for their efficacy against leaffolder pest and sheath blight disease on rice under glasshouse and field conditions. The combination of Pf1, AH1 and B2 effectively reduced the incidence of leaffolder insect and sheath blight disease on rice compared with other treatments. An in vitro assay of leaffolder preference to rice leaf tissues treated with Pf1 + AH1 + B2 biformulation showed variation from normal growth and development of leaffolder larvae. Plants treated with the Pf1 + AH1 + B2 combination showed a greater accumulation of enzymes, lipoxygenase and chitinase activity against leaffolder insect compared with other treatments. Similarly, the plants showed a higher accumulation of defence enzymes, peroxidase and polyphenol oxidase activity against sheath blight pathogen in Pf1 + AH1 + B2 treatment compared with the untreated control. The bioformulation mixture attracted the natural enemy population of leaffolder under field conditions. In addition, a significant increase in rice grain yield was observed in Pf1 + AH1 + B2 treatment compared with the untreated control. CONCLUSION: The combination of P. fluorescens strains and B. bassiana isolate effectively reduced the incidence of leaffolder insect and sheath blight disease on rice plants and showed the possibility of controlling both pest and disease using a single bioformulation. Copyright © 2010 Society of Chemical Industry  相似文献   

3.
Tomato root rot caused by Rhizoctonia solani is a major soilborne disease resulting in significant yield loss. The culture filtrates of six isolates of Trichoderma/Hypocrea species were evaluated for in vitro production of hydrolytic enzymes. Results demonstrated that all the six isolates were able to produce chitinase, β-1, 3 glucanase and protease in the range of 76–235 μmol GlcNAc min-1 mg-1 protein, 31.90–37.72 nmol glucose min-1 mg-1 proteins and 63.05–86.22 μmol min-1 mg-1 proteins, respectively. Trichoderma/Hypocrea-based formulation(s) were prepared with chitin (1% v:v) and CMC (0.5% w:v) for root rot management in a greenhouse. Root dip application with bioformulation(s) resulted in a significant reduction of the root rot index. In addition, bioformulations increased plant growth attributing traits significantly relative to untreated control. Accumulation of total phenols, peroxidase, polyphenoloxidase and phenylalanine ammonia lyase increased in chitin-supplemented Trichoderma/Hypocrea formulation-treated plants challenged with R. solani. The results suggest that chitin-fortified bioformulation(s) could be an effective system to control root rot of tomato in an eco-compatible manner.  相似文献   

4.
Three hundred and ninety-three groundnut-associated bacterial strains, applied both as seed treatment and soil amendment, were evaluated for control of stem rot disease (caused by Sclerotium rolfsii) of groundnut in a controlled environment. Twelve strains significantly (P=0.01) reduced the incidence of stem, rot of which groundnut seed endophytes Pseudomonas aeruginosa GSE 18 and GSE 19 reduced the seedling mortality by 54% and 58%, compared to the control. In dual cultures, the 12 biocontrol strains reduced the mycelial growth of S. rolfsii by 32%–74% as compared to the control. Cell- free culture filtrates of P. aeruginosa GSE 18 and GSE 19 inhibited the activity in vitro of the cell wall-degrading enzymes (CWDE) polygalacturonase and cellulase by S. rolfsii up to a maximum of 55% and 50%, respectively, when measured 6 days after inoculation. Pseudomonas aeruginosa GSE 18 and GSE 19 with a known tolerance to thiram, a commonly used seed dressing fungicide, suppressed the growth of S. rolfsii, inhibited the activity of CWDE, and reduced the incidence of stem rot, suggesting the usefulness of these biocontrol strains as components in the integrated management of groundnut stem rot.  相似文献   

5.
The pine wood nematode, Bursaphelenchus xylophilus, infects pine trees, leading to fatal pine wilt disease. Here, recombinant venom allergen-like protein (VAP) was obtained by expressing Bx-vap-1 in insect cells. Three-year-old Pinus massoniana were inoculated with recombinant VAP, simulating B. xylophilus esophageal gland secretions. Recombinant VAP up-regulated α-pinene synthase gene expression, the trees showed disease symptoms 15 d after inoculation and the xylem pith revealed brown tissue discoloration, indicating that recombinant VAP could damage P. massoniana cells. Recombinant VAP did not, however, lead to cavitation, indicating that the VAP secreted from B. xylophilus acts as a defense response elicitor.  相似文献   

6.
In this work, a bioformulation containing Trichoderma harzianum strain ITEM 3636, an effective biocontrol agent against the peanut pathogen Fusarium solani, was evaluated for control of peanut smut, an emergent disease caused by Thecaphora frezii. The performance of the bioformulation was evaluated during seasons 2014/2015 and 2015/2016 in experimental fields with history of peanut smut. Inoculation with T. harzianum ITEM 3636 significantly reduced the severity of peanut smut during both seasons by 17% and 25%, respectively. This is the first report where a consistent decrease of peanut smut symptoms is achieved in field experiments using a potential biological control agent. The identity of the causal agent of peanut smut was confirmed by sequencing the D1/D2 DNA region. T. harzianum ITEM 3636 caused significant increases in grain weight/plant in both years. Peanut smut and brown root rot are diseases that cause severe economic losses. Both causal agents may be present in the soil and, depending on environmental factors, cause disease. The T. harzianun ITEM 3636 bioformulation has high potential for controlling both diseases. Thus, the application of a single bioformulation could protect the health of peanut plants against two high impact pathogens.  相似文献   

7.
A liquid based Pseudomonas fluorescens (Pf1) bioformulation was found to contribute the restriction of Fusarium oxysporum f. sp. lycopersici in tomato roots by inducing defence enzymes. Induction of defence enzymes such as phenylalanine ammonia lyase (PAL), peroxidase (PO), polyphenoloxidase (PPO), catalase, β-1,3 glucanase and super oxide dismutase (SOD), was studied in tomato plants pretreated with liquid as well as a talc based formulation of Pf1 challenged with F. oxysporum f. sp. lycopersici in glasshouse vegetable production systems. There were increased activities of PAL, PO, PPO, catalase and β-1 3-glucanases in tomato plants treated with a combined application of seedling dip?+?soil application?+?foliar spray of liquid and talc formulation of Pf1 when compared to pathogen inoculated and untreated healthy controls. The activities of the above enzymes started to increase at 3rd day, reached maximum levels on 8-9th day and thereafter declined gradually. Similarly, native polyacralamide gel electrophoresis (PAGE) analysis revealed that one to six isoforms of the defence enzymes each with a higher intensity were expressed in these treatments, whereas fewer isoforms with less intensity were noticed in inoculated controls. These results suggest that the retardation of the invasion of F. oxysporum f. sp. lycopersici in tomato roots resulting from treatment with the liquid formulation of Pf1 was due to enhancement of activities of enzymes involved in the phenylpropanoid pathway. These results suggest that induced systemic resistance occurred in the treated tomato plants.  相似文献   

8.
In this review an effort was made to summarize the up to date information on the knowledge on the action mechanism of diflubenzuron (DFB), a prototype chemical for the benzoylurea type insecticides, with respect to its molecular mechanism to inhibit insect chitin synthesis. The key problem in pinpointing the action site of this insecticide has been the lack of in vitro demonstration of its action to inhibit insect chitin synthesis under cell free conditions. This problem was solved when an approach using a intracellular vesicle preparation from the cuticle of newly molted Periplaneta americana was developed. Using this approach it has become possible to identify that DFB indeed inhibits the process of incorporation of N-acetylglucosamine into insect chitin. Recently there has been a breakthrough in this field, when a sulfonylurea receptor (SUR) was identified in Drosophila melanogaster. This information was instrumental in establishing that insect SUR in the above intracellular vesicular preparation from P. americana as well as Blattella germanica is likely the actual target site of DFB to cause inhibition of chitin synthesis. The role of SUR in this case has been determined, by using glibenclamide, a typical SUR specific inhibitor as an aid, to be helping the exocytotic movement of these vesicles as is the case of other members of the group of ABC-transporters to which insect SUR belongs. In this case both DFB and glibenclamide have been shown to cause the depolarization of the vesicle membrane through inhibition of the K+ channel, which leads to their inhibition of chitin synthesis.  相似文献   

9.
The study showed significant differences in percent collar rot disease incidence in groundnut varieties grown in non-infested soil (T1), challenged with pathogen – Aspergillus niger (T2), and pathogen + Trichoderma viride 60 (T3) treatments. Total phenols revealed a significantly higher content in tolerant varieties (J-11, GG-2) of groundnut compared with moderately susceptible (GAUG-10, GG-13) and susceptible (GG-20) varieties. The phenol content accumulated at a higher rate (193%) in GG-20, followed by GG-2 (146%) and J-11 (107%) varieties during disease development stages. HPLC analysis detected six major phenolics, viz., hydroquinone, gallic, chlorogenic, ferulic, salicylic and cinnamic acids. Among six peaks, hydroquinone was found highest in GG-2 at 3 days in T3. Gallic and salicylic acids increased up to 9 days, while ferulic acid continued to induce up to 15 days in tolerant varieties (J-11, GG-2) of Trichoderma-treated (T3) seedlings. A correlation study indicated that Trichoderma treatment induced five phenolics – except gallic acid – with a higher level of significance in a susceptible variety to reduce disease incidence compared with tolerant varieties. Results demonstrate the T. viride 60 mediated systemic induction of phenolics for biologic control and their probable role in protecting groundnut against A. niger infection.  相似文献   

10.
The present study investigated resistance against Botrytis cinerea after heat shock treatment in melon plants. Heat shock at 50 °C for 20 s 0–24 h before inoculation resulted in maximal B. cinerea symptom reduction and peroxidase gene expression, which peaked 12 and 72 h post-treatment and decreased 24–48 h post-treatment, suggesting pathogenesis-related protein expression priming. Hot water dipping did not directly inhibit mycelia growth. Plants treated with 2-benzisothiazol-3(2H)-one 1,1-dioxide, which induces systemic acquired resistance, demonstrated higher peroxidase gene expression but no B. cinerea resistance, indicating possible involvement of additional novel mechanisms in heat shock-activated resistance of melon against B. cinerea.  相似文献   

11.
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12.
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13.
Stem rot caused by Sclerotium rolfsii is an important problem for Jerusalem artichoke production. Host plant resistance is the most promising method to control disease. If resistant genotypes can be identified in seedlings and this resistance is closely related to resistance at maturity, the evaluation of disease resistance in adult plants could be curtailed or omitted, increasing the speed and efficiency of screening. The objective of this study was to determine the relationship between resistance to S. rolfsii in Jerusalem artichoke in seedling and in adult stages under field conditions. Field experiments were set up in different soil fertility environments in the rainy season during July to October 2014. In each environment, 10 varieties of Jerusalem artichoke with differences in resistance to S. rolfsii were planted and inoculated either 15 or 45 days after transplanting. Higher disease incidence was observed on adult plant stage, but disease severity was similar for both plant stages. The correlations between seedling and adult responses were positive and significant for disease incidence, area under disease progress curve and severity index. Screening for resistance to S. rolfsii in Jerusalem artichoke can be carried out on seedlings, thus improving the efficiency of selection.  相似文献   

14.
This present study investigated the effects of heat shock treatments in strawberry seedlings against crown rot caused by Colletotrichum gloeosporioides. Heat shock treatment at 50 °C for 20 s reduced the disease index of strawberry crown rot and increased chitinase 2-1 gene expression as well as free salycilic acid accumulation. Heat shock treatment did not reduce mycelial growth of C. gloeosporioides. BIT(2-benzisothiazol-3(2H)-one,1,1-dioxide) treatment could not protect strawberry seedlings against crown rot disease. This finding suggests that heat shock induces strawberry resistance against Colletotrichum crown rot and assumes that mechanisms other than SAR probably mediated the protective effect of heat shock-induced resistance.  相似文献   

15.
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16.
Two bacterial isolates and one strain of Trichoderma harzianum were tested alone and in combination with chitin for efficacy in control of root rot disease caused by Phytophthora capsici and Rhizoctonia solani in pepper plants under greenhouse conditions. These bacteria (Bacillus subtilis HS93 and B. licheniformis LS674) were isolated from repeatedly washed roots of pepper plants. In in vitro assays, HS93, LS674 and T. harzianum were antagonistic against P. capsici and R. solani and produced high levels of chitinase. Seed treatment and root drenching with bacterial suspensions of HS93 with 0.5% chitin was more effective against Phytophthora and Rhizoctonia root rot than addition of the organisms without chitin. LS674 and T. harzianum reduced Rhizoctonia but not Phytophthora root rot. In two greenhouse tests, seed treatment and root drenching with HS93 amended with chitin enhanced its biocontrol activity against P. capsici but not on R. solani. The effects of LS674 and T. harzianum against R. solani were significantly enhanced when they were used as suspensions with 0.5% chitin for root drenching, but this had no effect on P. capsici. In both greenhouse experiments, the use of 0.5% chitin alone for root drenching reduced Rhizoctonia root rot. Reduction of root rot disease was accompanied by increased yield. These results show that the antagonistic activity of HS93, LS674 and T. harzianum may be stimulated by chitin resulting in significant improvements in their effectiveness against pathogens.  相似文献   

17.
Leaf blight, sheath blight, and web blight are major diseases caused by Rhizoctonia species on both Fabaceae and Poaceae plant hosts in the Brazilian Amazon agroecosystem. To determine the diversity of Rhizoctonia species associated with foliar diseases on fabaceous (cowpea and soybean) and poaceous (rice and signal grass [Urochloa brizantha]) hosts, a broad survey was conducted in Pará, Rondônia, Roraima, and Mato Grosso, in the Amazon, from 2012 to 2013. We extended our survey to Cerrado areas of Mato Grosso, and the lowlands of Paraíba Valley, in São Paulo, where these Rhizoctonia foliar diseases have not been reported so far. Our findings revealed that these diseases are caused by a diversity of Rhizoctonia solani AG-1 complex. We detected that R. solani AG-1 IA (sexual phase Thanatephorus cucumeris) was the predominant pathogen associated with signal grass leaf blight and collar rot diseases in the Amazon, especially in Rondônia and northern Mato Grosso. In addition, a subgroup of R. solani (AG-1 IF), not previously reported in Brazil, was associated with leaf blight on cowpea and soybean, in Roraima. Another subgroup (AG-1 ID) was also detected in Roraima. In Mato Grosso Cerrados we did not find any of the major Rhizoctonia foliar pathogens. Instead, R. oryzae (Waitea circinata) was the predominant species associated with a collar rot on U. brizantha. In the lowlands of São Paulo, R. oryzae-sativae (Ceratobasidium oryzae-sativae) was the predominant pathogen detected causing the rice sheath spot disease.  相似文献   

18.
Selected strains of rhizobacteria induce systemic resistance in plant (ISR), enhancing the capacity to mobilize infection-induced cellular defense responses (priming). Bacillus sp. CHEP5 and Pseudomonas sp BREN6 strains reduced root and stem wilt disease severity caused by Sclerotium rolfsii in Arachis hypogaea L. Strains inoculation increased the activity of phenylalanine ammonia-lyase and peroxidase, after pathogen-challenge, indicating priming. CHEP5 primes plants to produce more ethylene upon stimulation with ACC. A. hypogaea L is an ISR-positive plant and BREN6 and CHEP5 strains enhance the plant’s defense capacity by priming for potentiated activity of defense proteins and ACC-converting capacity.  相似文献   

19.
Rhizoctonia crown and root rot (RCRR), caused by Rhizoctonia solani Kühn AG 2-2 IIIB, is an important disease of sugar beet. While RCRR can be managed by agronomic practices, plant resistance remains the primary method for control. However, the molecular processes that mediate resistance to R. solani are largely unknown. The metabolic changes that occurred during susceptible and resistant R. solani interactions were compared and characterized using nontargeted metabolomic profiling. Metabolites from infected and healthy, root and leaf tissue, were taken at 0 and 7 dai and detected using reversed-phase UHPLC-MS and GC-MS. There was a clear distinction in the metabolome between tissue type and genotype, and in response to R. solani. 143 compounds were annotated and several metabolites associated with plant defense to fungi were identified in both germplasm.  相似文献   

20.
Banana wilt disease is a typical vascular disease caused by the fungal pathogen Fusarium oxysporum f. sp. cubense 4 (Foc 4). Pattern recognition receptors in the plant cell membrane can recognize pathogen-associated molecular patterns (PAMPs) to activate multi-layer defense responses, including defense gene expression, stomatal closure, reactive oxygen species (ROS) burst and callose deposition, to limit pathogen growth. In the present study, we found that chitin elicitor receptor kinase 1 (CERK1) was required for the non-host resistance of Arabidopsis thaliana to Foc B2 (a strain of Foc 4). The cerk1 mutant had weaker defense responses after Foc B2 treatment, including lower expression of PAMP- and salicylic acid-responsive genes, no stomatal closure, lower ROS level and less callose deposition, than that of the wild-type plant. Consistent with this, the cerk1 mutant plants exhibited higher susceptibility to non-host pathogen Foc B2. These results suggest the crucial importance of CERK1 in Foc B2-triggered non-host resistance.  相似文献   

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