Blast of Rice in Manipur and its Biocontrol by Pseudomonas fluorescens and Trichoderma sp.
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Blast of rice (Oryza sativae L.) caused by Pyricularia oryzae is one of the most destructive disease in Manipur giving losses ranging from 60 to 100%. In the present investigation, biocontrol of this disease was attempted by isolating local strains of Pseudomonas fluorescens and Trichoderma spp. P. fluorescens B 24 gave maximum mycellial inhibition (77.5%) among the bacterial biocontrol and T. koningiopsis T 162 gave maximum inhibition of 46.25%. Seed germination, root and shoot length were enhanced by single treatment (B 24) in vitro conditions. Plant height was also increased by 5% in greenhouse and 12.02% in field trial with single application (B 24). However, greenhouse and field data revealed significant reduction in Blast incidence (5.1% and 3.4%), lesion number (35.53% and 58.72%) and size (18.86%, 16.39%) when applied in consortia (B 24+ T 162) as compared to single application (B 24) resulting in incidence of 6.7% and 3.92%, lesion number of 33.33% and 14.67%, size of 15.09% and 27.83% irrespective of greenhouse and field trial. The results indicated the effectiveness of combined application of P. fluorescens B 24 and T. koningiopsis T 162 for plant growth promotion and control of Blast of rice and therefore can be integrated for managing Blast of rice.Keywords:
Pseudomonas fluorescens
Pyricularia
Seed treatment
Blast disease
Trichoderma
Field trial
Blast of rice (Oryza sativae L.) caused by Pyricularia oryzae is one of the most destructive disease in Manipur giving losses ranging from 60 to 100%. In the present investigation, biocontrol of this disease was attempted by isolating local strains of Pseudomonas fluorescens and Trichoderma spp. P. fluorescens B 24 gave maximum mycellial inhibition (77.5%) among the bacterial biocontrol and T. koningiopsis T 162 gave maximum inhibition of 46.25%. Seed germination, root and shoot length were enhanced by single treatment (B 24) in vitro conditions. Plant height was also increased by 5% in greenhouse and 12.02% in field trial with single application (B 24). However, greenhouse and field data revealed significant reduction in Blast incidence (5.1% and 3.4%), lesion number (35.53% and 58.72%) and size (18.86%, 16.39%) when applied in consortia (B 24+ T 162) as compared to single application (B 24) resulting in incidence of 6.7% and 3.92%, lesion number of 33.33% and 14.67%, size of 15.09% and 27.83% irrespective of greenhouse and field trial. The results indicated the effectiveness of combined application of P. fluorescens B 24 and T. koningiopsis T 162 for plant growth promotion and control of Blast of rice and therefore can be integrated for managing Blast of rice.
Pseudomonas fluorescens
Pyricularia
Seed treatment
Blast disease
Trichoderma
Field trial
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Activation of abiotic temperature stress tolerance in transgenic Bt and non-Bt cotton was studied using Pseudomonas fluorescens as biotic regulator. Seeds germinated at different temperatures after the bacterial treatment exhibited variation at the temperatures of 30°C and 37°C as measured in terms of percent seed germination in both Bt and non-Bt cotton. Pseudomonas treatment enhanced the seed germination in non-Bt cotton at 30°C. Enhancement of seed germination in Bt cotton was significant at 37°C after bacterial treatment. At elevated temperature of 45°C, neither Bt nor non-Bt seeds germinated, irrespective of Pseudomonas treatment. The temperature of 30°C supported better shoot and root growth of seedlings as compared to other temperatures tested. Pseudomonas treatment resulted in enhanced shoot and root length of Bt cotton seedlings at 30°C, whereas at 37° Chad negligible influence. Non-Bt cotton seeds treated with bacteria failed to show significant variation in root and shoot growth compared to untreated control. Activity gelelectrophoresis carried out to study the expression of superoxide dismutase revealed that the SOD activity in both Bt and non-Bt cotton was enhanced due to Pseudomonas seed treatment.
Pseudomonas fluorescens
Seed treatment
Bt Cotton
Gossypium
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Thirty-nine rice (Oryza sativa) hybrids and their restorers were assessed for vertical resistance to Pyricularia grisea in the rice blast nursery, and in artificial inoculation tests with two pathotypes, under controlled greenhouse conditions. The hybrids were developed from cytoplasmic genetic male sterile lines 046I and IR 58025A, derived from WA cytoplasm. In the rice blast nursery all hybrids showed susceptible reaction varying from 5 to 9. Compatible and incompatible leaf blast reactions of hybrids to two pathotypes, IC-1 and IB-45, were observed in inoculation tests. A majority of the hybrids were resistant when the restorer was resistant. However, seven of the 25 F1 hybrids exhibited susceptible reactions even when one of the parents was resistant to a pathotype. The partial resistance of 11 hybrids and their parents that showed compatible reactions to two pathotypes was analyzed. Differential interaction between isolates and genotypes was observed for partial resistance in relation to both disease severity and lesion number indicating the specific nature of partial resistance.
Pyricularia
Blast disease
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Pseudomonas fluorescens
Strain (injury)
Colonisation
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Pseudomonas fluorescens strain Pf1, inhibitory to the growth of the rice blast pathogen Pyricularia oryzae in vitro , was developed as a talc‐based powder formulation. When rice seeds were treated with this formulation, the bacteria spread to roots, stems and leaves of the plants and protected against leaf infection by P. oryzae . When applied as a foliar spray, the bacteria survived on the leaves. The powder formulation controlled leaf blast under greenhouse conditions. In tests as a seed treatment and foliar spray in four field trials it effectively controlled the disease and increased grain yield.
Pyricularia
Pseudomonas fluorescens
Blast disease
Talc
Strain (injury)
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Fungi of the genus Trichoderma are important microorganisms used in biocontrol processes and the promotion of plant development. However, they remain poorly studied in the context of forestry programs, especially those related to native Amazonian species. Thus, it is the aim of this study to evaluate the effects of different Trichoderma isolates on the germination and development of Handroanthus serratifolius seedlings. During in vitro germination tests, seeds were immersed for 24 h in respective fungal suspensions each prepared using one of five Trichoderma isolates. The suspensions were held in plastic trays and kept at a temperature of 24 ± 2 °C. Metrics related to germination and development assessed under laboratory conditions include: germination speed index (GSI), germination percentage, length of the roots, and hypocotyls, as well as fungal perseverance. In the nursery, Trichoderma were used in two different applications: pre-planting treatment and as a monthly, post-planting treatment. Pre-planting treatments consisted of 10 g of colonized rice grains bearing each isolate being placed into experimental bags five days before seeding. The post-planting treatment involved the application of 10 mL of fungal suspension per experimental bag. Each month, the height, stem diameter, and leaf number were measured for each seedling. At the end of the experiment, the length and mass of roots as well as the total dry mass were recorded. In laboratory conditions, seeds treated with Trichoderma asperellum -TAM03 obtained the greatest fractional germination (76.5%) and GSI. In the nursery experiments, isolates TAM01 and TAM03, when applied as a post-planting treatment, increased the height, stem diameter, and number of leaves of treated plants with respect to the control group by 180 days post-treatment. After 365 days, plants which received TAM01 pre-planting treatments were observed to have increased root and aerial part length, as well as root mass and overall dry mass. These results suggest that T. asperellum -TAM01 positively affects H. serratifolius development.
Trichoderma
Seed treatment
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Rice is most important source to worldwide, especially in Malaysia in term of economic and as source of food. Moreover, rice is becoming sources of income for smallholder farmers. However, in this globalization the production of rice unable to fulfil the population demand because of the present of diseases. Rice blast is one of major diseases that causes by Pyricularia oryae and known as the most destruction disease that potential to cause 100% loss of yield under a favorable conditions. Although there have a lot of methods to control P. oryzae included use resistant varieties, applying fungicide and rotation farming unfortunately all of those method not long lasting. The aims of these study were to isolate Trichoderma spp. as a biological control agents against P. oryzae and to observe the inhibition of P. oryzae by Trichoderma spp. in vivo assays. Meanwhile, for species level of identify of Trichoderma spp. were done based on colony color and shape of conidia. There five of isolates of Trichoderma spp. which is TH1, TH2, TH3, TH4 and TM1. The potential of Trichoderma spp. to control P. oryzae was observed using dual culture technique. As biological control agent, isolates of Trichoderma spp. showed more than 50% growth inhibition of P. oryzae on the seven days of incubation in dual culture method and TM1 is the most effective among five isolates.
Pyricularia
Trichoderma
Blast disease
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Pyricularia
Blast disease
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Pyricularia
Magnaporthe
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Information on the effects of released wild-type or genetically engineered bacteria on resident bacterial communities is important to assess the potential risks associated with the introduction of these organisms into agroecosystems. The rifampicin-resistant biocontrol strain Pseudomonas fluorescens CHA0-Rif and its derivative CHA0-Rif/pME3424, which has improved biocontrol activity and enhanced production of the antibiotics 2,4-diacetylphloroglucinol (Phl) and pyoluteorin (Plt), were introduced into soil microcosms and the culturable bacterial community developing on cucumber roots was investigated 10 and 52 days later. The introduction of either of the two strains led to a transiently enhanced metabolic activity of the bacterial community on glucose dimers and polymers as measured with BIOLOG GN plates, but natural succession between the two sampling dates changed the metabolic activity of the bacterial community more than did the inoculants. The introduced strains did not significantly affect the abundance of dominant genotypic groups of culturable bacteria discriminated by restriction analysis of amplified 16S rDNA of 2500 individual isolates. About 30–50% of the resident bacteria were very sensitive to Phl and Plt, but neither the wild-type nor CHA0-Rif/pME3424 changed the proportion of sensitive and resistant bacteria in situ. In microcosms with a synthetic bacterial community, both biocontrol strains reduced the population of a strain of Pseudomonas but did not affect the abundance of four other bacterial strains including two highly antibiotic-sensitive isolates. We conclude that detectable perturbations in the metabolic activity of the resident bacterial community caused by the biocontrol strain CHA0-Rif are (i) transient, (ii) similar for the genetically improved derivative CHA0-Rif/pME3424 and (iii) less pronounced than changes in the community structure during plant growth.
Pseudomonas fluorescens
Microcosm
Antibiosis
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