The effect of the hyperparasite (Gliocladium virens) on Rhizoctonia solani and on Rhizoctonia root rot of white beans

1981 ◽  
Vol 59 (1) ◽  
pp. 22-27 ◽  
Author(s):  
J. C. Tu ◽  
O. Vaartaja
Keyword(s):  
Rhizoctonia Solani ◽  
Root Rot ◽  
Biological Control Agent ◽  
Light And Electron Microscopy ◽  
Control Agent ◽  
Host Cells ◽  
Sequence Of Events ◽  
Rhizoctonia Root Rot ◽  
Gliocladium Virens

Using light and electron microscopy, Gliocladium virens is proved to be a hyperparasite of Rhizoctonia solani. When hyphae of G. virens come in contact with those of R. solani, the following sequence of events are observed (i) contact of G. virens with host cells, (ii) formation of appresoria, (iii) penetration of host cells, (iv) formation of intracellular hyphae, and (v) collapse and death of host cells. In vitro, G. virens effectively inhibited sclerotial formation of R. solani.Greenhouse tests showed that the presence of G. virens in soil artificially infested with R. solani reduced at planting the severity of Rhizoctonia root rot in white beans. Root rot severity decreased with increasing concentrations of G. virens. A similar result was obtained in soil treated with the two fungi 2 months prior to planting. This study suggests that G. virens may be a promising biological control agent for Rhizoctonia root rot of white beans.

scholarly journals Growth and Maintenance of Wolbachia in Insect Cell Lines

Insects ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 706
Author(s):  
Ann M. Fallon
Keyword(s):  
Cell Lines ◽  
Insect Cell ◽  
Cultured Cells ◽  
Biological Control Agent ◽  
Wolbachia Infection ◽  
Control Agent ◽  
Host Cells ◽  
Gene Drive ◽  
Insect Cell Lines

The obligate intracellular microbe, Wolbachia pipientis (Rickettsiales; Anaplasmataceae), is a Gram-negative member of the alpha proteobacteria that infects arthropods and filarial worms. Although closely related to the genera Anaplasma and Ehrlichia, which include pathogens of humans, Wolbachia is uniquely associated with invertebrate hosts in the clade Ecdysozoa. Originally described in Culex pipiens mosquitoes, Wolbachia is currently represented by 17 supergroups and is believed to occur in half of all insect species. In mosquitoes, Wolbachia acts as a gene drive agent, with the potential to modify vector populations; in filarial worms, Wolbachia functions as a symbiont, and is a target for drug therapy. A small number of Wolbachia strains from supergroups A, B, and F have been maintained in insect cell lines, which are thought to provide a more permissive environment than the natural host. When transferred back to an insect host, Wolbachia produced in cultured cells are infectious and retain reproductive phenotypes. Here, I review applications of insect cell lines in Wolbachia research and describe conditions that facilitate Wolbachia infection and replication in naive host cells. Progress in manipulation of Wolbachia in vitro will enable genetic and biochemical advances that will facilitate eventual genetic engineering of this important biological control agent.

scholarly journals Uji Antagonisme Bacillus cereus terhadap Rhizoctonia solani dan Sclerotium rolfsii

2016 ◽  
Vol 7 (1) ◽  
pp. 1
Author(s):  
Nurul Hidayah ◽  
Titiek Yulianti
Keyword(s):  
Biological Control ◽  
Growth Rate ◽  
Rhizoctonia Solani ◽  
Biological Control Agent ◽  
Sclerotium Rolfsii ◽  
Control Agent ◽  
Dual Culture ◽  
Bacillus Sp ◽  
Unfavorable Condition

<p>Jamur Rhizoctonia solani dan Sclerotium rolfsii merupakan kelompok jamur steril (tidak menghasilkan spora) tetapi dapat menghasilkan sklerosia sebagai sumber inokulum primer, dan struktur istirahat jamur yang dapat bertahan selama beberapa tahun di dalam tanah saat kondisi lingkungan kurang menguntungkan. Penggunaan fungisida, fumigasi, dan solarisasi tanah telah digunakan untuk mengendalikan kedua jamur tersebut, namun hasil yang diperoleh masih beragam. Pengendalian hayati dengan menggunakan bakteri Bacillus sp. yang merupakan salah satu kelompok agens hayati patogen diketahui memberikan hasil yang baik pada beberapa tanaman. Penelitian yang bertujuan menguji potensi B. cereus dalam menghambat pertumbuhan jamur R. solani dan S. rolfsii secara in vitro dilaksanakan di Laboratorium Fitopatologi Balittas dengan menggunakan metode dual culture pada media potato dextrose agar (PDA). Miselia jamur R. solani dan S. rolfsii masing-masing berumur 5 hari diambil dengan menggunakan cork borer ukuran 0,5 cm ditanam pada media PDA berhadapan dengan B. cereus dengan jarak 3 cm. Penelitian disusun dalam rancangan acak lengkap dan diulang empat kali. Pengamatan dilakukan terhadap persentase penghambatan pertumbuhan jamur oleh Bacillus sp. dan laju pertumbuhan jamur. Hasil penelitian menunjukkan bahwa Bacillus sp. mampu menghambat pertumbuhan miselia R. solani dan S. rolfsii masing-masing sebesar 68,9% dan 33% pada hari ketiga setelah perlakuan. Keberadaan B. cereus dapat memperlambat laju pertumbuhan R. solani (15,5 mm/24 jam), dibandingkan perlakuan kontrol (tanpa B. cereus) sebesar 19,7 mm/24 jam. Hasil ini menunjukkan bahwa B. cereus dapat menghambat pertumbuhan R. solani dan berpotensi untuk dikembangkan sebagai agens hayati.</p><p> </p><p>Rhizoctonia solani and Sclerotium rolfsii (the causal agents of damping off disease on various hosts) are the group of sterile fungi that cannot produce spores. Nevertheless, they produce sclerotia as primary inocula and resting spores when facing unfavorable condition. Several control methods using chemical fungicides and solarization had been conducted, but the results were still inconsistent. In addition, the use of Bacillus sp. as a biological control agent for several plant diseases had provided successful results. Furthermore, the research aimed to evaluate the potency of B. cereus towards R. solani and S. rolfsii in vitro was carried out in the laboratory of phytopathology using dual culture method on PDA medium. Five days of R. solani and S. rolfsii miselia were plugged and inoculated on PDA medium toward B. cereus. The research was arranged by completely randomized design with four replicates. The percentage of fungal inhibition and fungal growth rate were observed. The result showed that B. cereus exhibited mycelial growth inhibition activity of R. solani and S. rolfsii by 68,9% and 33% three days after treatments, respectively. The result also indicated that<br />B. cereus has a potential prospect to be developed as a biological control agent because the bacteria could suspend the growth rate of R. solani.</p>

scholarly journals Use of Pseudomonas aeruginosa in the control od root-knot disease complex in tomato: the effects of different inoculum levels of Meloidogyne javanica and Rhizoctonia solani

2013 ◽  
Vol 54 (1) ◽  
pp. 45-54 ◽  
Author(s):  
I. A. Siddiqui ◽  
S. Ehteshamul-Haque ◽  
S. S. Shaukat
Keyword(s):  
Rhizoctonia Solani ◽  
Root Rot ◽  
Root Colonization ◽  
Biological Control Agent ◽  
Meloidogyne Javanica ◽  
Macrophomina Phaseolina ◽  
Control Agent ◽  
Population Densities ◽  
Culture Suspension ◽  
Rot Disease

The potential impact of <em>Pseudomons aeruginosa</em> strain IE-6 as a biological control agent against <em>Meloidogyne javanica</em> at four inoculum densities (0, 250, 500 and 1000 eggs/plant) and <em>Rhizoctonia solani</em> at three inoeulum levels (0, 1 and 3 ml culture suspension/kg of soil) was examined on tomato in the greenhouse experiments. The biocontrol bacterium suppressed root infection caused by <em>R. solani</em> and <em>M. javanica</em> on tomato in both sterilized and non-sterilized soils. Root-rot infection increased with the increase in pathogen(s) concentration. <em>P. aeruginosa</em> showed better biocontrol effects at low population levels of <em>M.javanica</em> and <em>R. solani</em> than at higher population densities of the pathogen(s). Root-rot disease severity was more pronounced in sterilized soil compared to the non-sterilized one. Soil infested with high population densities ofR. solani (3 ml /kg of soil) and <em>M. javanica</em> (2000 eggs/pot) resulted in complete mortality of tomato seedlings in sterilized soil, whereas some plants were found to survive in non-stenlized soil. There seems to be a correlation between population density of <em>M. javanica</em> and root colonization by <em>R. solani</em>. Root colonization by other three root-infecting fungi including <em>Macrophomina phaseolina, Fusarium oxysporum</em> and <em>Fusarium solani</em> was also lower in the presence of <em>P. aeruginosa</em> in non-sterilized soil. <em>P. aeruginosa</em> enhanced plant growth in both types of soil.

scholarly journals Effect of Timing of Application of the Biological Control Agent Microsphaeropsis ochracea on the Production and Ejection Pattern of Ascospores by Venturia inaequalis

2004 ◽  
Vol 94 (12) ◽  
pp. 1305-1314 ◽  
Author(s):  
O. Carisse ◽  
D. Rolland
Keyword(s):  
Biological Control ◽  
Biological Control Agent ◽  
Venturia Inaequalis ◽  
Apple Scab ◽  
Control Agent ◽  
Sterile Leaf ◽  
Ascospore Production ◽  
Fall Application ◽  
Leaf Disks

Field and in vitro trials were conducted to establish the influence of the biological control agent Microsphaeropsis ochracea on the ejection pattern of ascospores by Venturia inaequalis and on apple scab development, and to establish the best timing of application. The ejection pattern of ascospores was similar on leaves sprayed with M. ochracea and on untreated leaves. Fall application of M. ochracea combined with a delayed-fungicide program was evaluated in orchards with intermediate and high scab risk. For both orchards, it was possible to delay the first three and two infection periods in 1998 and 1999, respectively, without causing significant increase or unacceptable leaf and fruit scab incidence. To evaluate the best timing of application, sterile leaf disks were inoculated with V. inaequalis and then with M. ochracea 0, 2, 4, 6, 8, 10, 12, 14, and 16 weeks later. After incubation under optimal conditions for pseudothecia development, the number of ascospores was counted. Similarly, M. ochracea was sprayed on scabbed leaves on seven occasions from August to November 1999 and 2000. Leaves were overwintered on the orchard floor and ascospore production was evaluated the following spring. Ascospore production was reduced by 97 to 100% on leaf disks inoculated with M. ochracea less than 6 weeks after inoculation with V. inaequalis, but ascospore production increased with increasing period of time when M. ochracea was applied 8 to 16 weeks after the inoculation with V. inaequalis. In the orchard, the greatest reduction in production of ascospores (94 to 96% in 2000 and 99% in 2001) occurred on leaves sprayed with M. ochracea in August. The production of ascospores was reduced by 61 to 84% in 2000 and 93% in 2001 on leaves sprayed with M. ochracea in September, reduced by 64 to 86% in 2000 and 74 to 89% in 2001 on leaves sprayed in October, and reduced by 54 and 67% in 2000 and 2001, respectively, on leaves sprayed in November. It was concluded that M. ochracea should be applied in August or September and that ascospore maturation models and delayed-fungicide program could be used in orchards treated with this biological control agent.

scholarly journals Sensitivity of Rhizoctonia solani AG-2-2 from Sugar Beet to Fungicides

Plant Disease ◽  
2016 ◽  
Vol 100 (12) ◽  
pp. 2427-2433 ◽  
Author(s):  
Sahar Arabiat ◽  
Mohamed F. R. Khan
Keyword(s):  
Sugar Beet ◽  
Rhizoctonia Solani ◽  
Root Rot ◽  
The United States ◽  
Damping Off ◽  
Growth Assay ◽  
The Mean ◽  
Crown And Root Rot ◽  
Mean Concentration

Rhizoctonia damping-off and crown and root rot caused by Rhizoctonia solani are major diseases of sugar beet (Beta vulgaris L.) worldwide, and growers in the United States rely on fungicides for disease management. Sensitivity of R. solani to fungicides was evaluated in vitro using a mycelial radial growth assay and by evaluating disease severity on R. solani AG 2-2 inoculated plants treated with fungicides in the greenhouse. The mean concentration that caused 50% mycelial growth inhibition (EC50) values for baseline isolates (collected before the fungicides were registered for sugar beet) were 49.7, 97.1, 0.3, 0.2, and 0.9 μg ml−1 and for nonbaseline isolates (collected after registration and use of fungicides) were 296.1, 341.7, 0.9, 0.2, and 0.6 μg ml−1 for azoxystrobin, trifloxystrobin, pyraclostrobin, penthiopyrad, and prothioconazole, respectively. The mean EC50 values of azoxystrobin, trifloxystrobin, and pyraclostrobin significantly increased in the nonbaseline isolates compared with baseline isolates, with a resistant factor of 6.0, 3.5, and 3.0, respectively. Frequency of isolates with EC50 values >10 μg ml−1 for azoxystrobin and trifloxystrobin increased from 25% in baseline isolates to 80% in nonbaseline isolates. Although sensitivity of nonbaseline isolates of R. solani to quinone outside inhibitors decreased, these fungicides at labeled rates were still effective at controlling the pathogen under greenhouse conditions.

scholarly journals Isolation, Characterization, and Identification of Biological Control Agent for Potato Soft Rot in Bangladesh

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
M. M. Rahman ◽  
M. E. Ali ◽  
A. A. Khan ◽  
A. M. Akanda ◽  
Md. Kamal Uddin ◽  
...  
Keyword(s):  
Biological Control ◽  
Biological Control Agent ◽  
Erwinia Carotovora ◽  
Soft Rot ◽  
Control Agent ◽  
Antagonistic Activity ◽  
Antagonistic Effect ◽  
Antagonistic Bacteria ◽  
And Storage

A total of 91 isolates of probable antagonistic bacteria of potato soft rot bacteriumErwinia carotovorasubsp.carotovora(Ecc) were extracted from rhizospheres and endophytes of various crop plants, different soil varieties, and atmospheres in the potato farming areas of Bangladesh. Antibacterial activity of the isolated probable antagonistic bacteria was testedin vitroagainst the previously identified most common and most virulent soft rot causing bacterial strain Ecc P-138. Only two isolates E-45 and E-65 significantly inhibited thein vitrogrowth of Ecc P-138. Physiological, biochemical, and carbon source utilization tests identified isolate E-65 as a member of the genusBacillusand the isolate E-45 asLactobacillussp. The stronger antagonistic activity against Ecc P-138 was found in E-65in vitroscreening and storage potatoes. E-65 reduced the soft rot infection to 22-week storage potatoes of different varieties by 32.5–62.5% in model experiment, demonstrating its strong potential to be used as an effective biological control agent for the major pectolytic bacteria Ecc. The highest (62.5%) antagonistic effect of E-65 was observed in the Granola and the lowest (32.7%) of that was found in the Cardinal varieties of the Bangladeshi potatoes. The findings suggest that isolate E-65 could be exploited as a biocontrol agent for potato tubers.

scholarly journals Prediction and Characterization of RXLR Effectors in Pythium Species

2020 ◽  
Vol 33 (8) ◽  
pp. 1046-1058 ◽  
Author(s):  
Gan Ai ◽  
Kun Yang ◽  
Wenwu Ye ◽  
Yuee Tian ◽  
Yaxin Du ◽  
...  
Keyword(s):  
Genome Rearrangement ◽  
De Novo ◽  
Biological Control Agent ◽  
Protein Structures ◽  
Control Agent ◽  
Phytophthora Species ◽  
Host Cells ◽  
Pythium Species ◽  
Origin And Evolution ◽  
Rxlr Effectors

RXLR effectors, a class of secreted proteins that are transferred into host cells to manipulate host immunity, have been reported to widely exist in oomycetes, including those from genera Phytophthora, Hyaloperonospora, Albugo, and Saprolegnia. However, in Pythium species, no RXLR effector has yet been characterized, and the origin and evolution of such virulent effectors are still unknown. Here, we developed a modified regular expression method for de novo identification of RXLRs and characterized 359 putative RXLR effectors in nine Pythium species. Phylogenetic analysis revealed that all oomycetous RXLRs formed a single superfamily, suggesting that they might have a common ancestor. RXLR effectors from Pythium and Phytophthora species exhibited similar sequence features, protein structures, and genome locations. In particular, there were significantly more RXLR proteins in the mosquito biological control agent P. guiyangense than in the other eight Pythium species, and P. guiyangense RXLRs might be the result of gene duplication and genome rearrangement events, as indicated by synteny analysis. Expression pattern analysis of RXLR-encoding genes in the plant pathogen P. ultimum detected transcripts of the majority of the predicted RXLR genes, with some RXLR effectors induced in infection stages and one RXLR showing necrosis-inducing activity. Furthermore, all predicted RXLR genes were cloned from two biocontrol agents, P. oligandrum and P. periplocum, and three of the RXLR genes were found to induce a defense response in Nicotiana benthamiana. Taken together, our findings represent the first evidence of RXLR effectors in Pythium species, providing valuable information on their evolutionary patterns and the mechanisms of their interactions with diverse hosts.

Effectiveness of 3 antagonistic bacterial isolates to control Rhizoctonia solani Kühn on lettuce and potato

2005 ◽  
Vol 51 (4) ◽  
pp. 345-353 ◽  
Author(s):  
Rita Grosch ◽  
Franziska Faltin ◽  
Jana Lottmann ◽  
A Kofoet ◽  
Gabriele Berg
Keyword(s):  
Rhizoctonia Solani ◽  
Pseudomonas Fluorescens ◽  
Biological Control Agent ◽  
Dry Mass ◽  
Control Agent ◽  
Disease Suppression ◽  
Growth Chamber ◽  
Bacterial Strains ◽  
Serratia Plymuthica ◽  
Suppression Effect

Rhizoctonia solani causes yield losses in numerous economically important European crops. To develop a biocontrol strategy, 3 potato-associated ecto- and endophytically living bacterial strains Pseudomonas fluorescens B1, Pseudomonas fluorescens B2, and Serratia plymuthica B4 were evaluated against R. solani in potato and in lettuce. The disease-suppression effect of the 3 biocontrol agents (BCAs) was tested in a growth chamber and in the field. In growth chamber experiments, all 3 BCAs completely or significantly limited the dry mass (DM) losses on lettuce and the disease severity (DS) caused by R. solani on potato sprouts. Strain B1 showed the highest suppression effect (52% on average) on potato. Under field conditions, the DS on both crops, which were bacterized, decreased significantly, and the biomass losses on lettuce decreased significantly as well. The greatest disease-suppression effect on potato was achieved by strain B1 (37%), followed by B2 (33%) and then B4 (31%), whereas the marketable tuber yield increased up to 12% (B1), 6% (B2), and 17% (B4) compared with the pathogen control at higher disease pressure. Furthermore, in all experiments, B1 proved to be the most effective BCA against R. solani. Therefore, this BCA could be a candidate for developing a commercial product against Rhizoctonia diseases. To our knowledge, this is the first report on the high potential of endophytes to be used as a biological control agent against R. solani under field conditions.Key words: biocontrol, Rhizoctonia solani, field grown lettuce and potato, antagonistic bacteria, endophytes.

scholarly journals Pseudomonas synxantha 2-79 Transformed with Pyrrolnitrin Biosynthesis Genes Has Improved Biocontrol Activity Against Soilborne Pathogens of Wheat and Canola

2020 ◽  
Vol 110 (5) ◽  
pp. 1010-1017
Author(s):  
Jibin Zhang ◽  
Dmitri V. Mavrodi ◽  
Mingming Yang ◽  
Linda S. Thomashow ◽  
Olga V. Mavrodi ◽  
...  
Keyword(s):  
Root Rot ◽  
Fusarium Culmorum ◽  
Pythium Ultimum ◽  
Gaeumannomyces Graminis ◽  
Wild Type ◽  
Wheat Roots ◽  
Recombinant Strains ◽  
Rhizoctonia Root Rot ◽  
Take All

A four-gene operon (prnABCD) from Pseudomonas protegens Pf-5 encoding the biosynthesis of the antibiotic pyrronitrin was introduced into P. synxantha (formerly P. fluorescens) 2-79, an aggressive root colonizer of both dryland and irrigated wheat roots that naturally produces the antibiotic phenazine-1-carboxylic acid and suppresses both take-all and Rhizoctonia root rot of wheat. Recombinant strains ZHW15 and ZHW25 produced both antibiotics and maintained population sizes in the rhizosphere of wheat that were comparable to those of strain 2-79. The recombinant strains inhibited in vitro the wheat pathogens Rhizoctonia solani anastomosis group 8 (AG-8) and AG-2-1, Gaeumannomyces graminis var. tritici, Sclerotinia sclerotiorum, Fusarium culmorum, and F. pseudograminearum significantly more than did strain 2-79. Both the wild-type and recombinant strains were equally inhibitory of Pythium ultimum. When applied as a seed treatment, the recombinant strains suppressed take-all, Rhizoctonia root rot of wheat, and Rhizoctonia root and stem rot of canola significantly better than did wild-type strain 2-79.

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