Perforation of hyphae and sclerotia of Rhizoctonia solani Kuehn by mycophagous soil amoebae from vegetable field soils in Japan.

Homma, Yukihiko; Ishii, Masayoshi

doi:10.3186/jjphytopath.50.229

Cited by 10 publications

(6 citation statements)

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“…This finally led to the erection of the new taxon Platyreta germanica [11] . Apart from P. germanica and T. weberi further isolates from soil indicate a considerable diversity of terrestrial vampyrellids with a wide geographical distribution [59] , [68] , [75] , [79] , [80] . A nderson & P atrick , for example, investigated different mycophagous vampyrellids, which produced at least three different types of holes in the cell walls of the conidia of Cochliobolus sativus [59] .…”

Section: Discussionmentioning

confidence: 99%

“…A nderson & P atrick , for example, investigated different mycophagous vampyrellids, which produced at least three different types of holes in the cell walls of the conidia of Cochliobolus sativus [59] . Other isolates from the USA and Japan turned out to feed on fungal hyphae, too [68] , [80] . In general, the assignment of taxonomic names such as V. lateritia or V. vorax to these isolates must be taken with reservation.…”

Section: Discussionmentioning

confidence: 99%

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Shedding Light on Vampires: The Phylogeny of Vampyrellid Amoebae Revisited

2012

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With the advent of molecular phylogenetic techniques the polyphyly of naked filose amoebae has been proven. They are interspersed in several supergroups of eukaryotes and most of them already found their place within the tree of life. Although the ‘vampire amoebae’ have attracted interest since the middle of the 19th century, the phylogenetic position and even the monophyly of this traditional group are still uncertain. In this study clonal co-cultures of eight algivorous vampyrellid amoebae and the respective food algae were established. Culture material was characterized morphologically and a molecular phylogeny was inferred using SSU rDNA sequence comparisons. We found that the limnetic, algivorous vampyrellid amoebae investigated in this study belong to a major clade within the Endomyxa Cavalier-Smith, 2002 (Cercozoa), grouping together with a few soil-dwelling taxa. They split into two robust clades, one containing species of the genus Vampyrella Cienkowski, 1865, the other containing the genus Leptophrys Hertwig & Lesser, 1874, together with terrestrial members. Supported by morphological data these clades are designated as the two families Vampyrellidae Zopf, 1885, and Leptophryidae fam. nov. Furthermore the order Vampyrellida West, 1901 was revised and now corresponds to the major vampyrellid clade within the Endomyxa, comprising the Vampyrellidae and Leptophryidae as well as several environmental sequences. In the light of the presented phylogenetic analyses morphological and ecological aspects, the feeding strategy and nutritional specialization within the vampyrellid amoebae are discussed.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Shedding Light on Vampires: The Phylogeny of Vampyrellid Amoebae Revisited

2012

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“…Fifteen plugs of R. solani were added to the culture and the dish was sealed with Parafilm then stored in a plastic bag. To separate the two species, co-cultures of V. vermiformis and R. solani for SEM were prepared following a modified procedure from Homma and Ishii [6]. Two nucleopore membranes (25 mm in diameter; Whatman #110610; Maidstone, United Kingdom) with 1.0 µm pores were used to sandwich three fungal discs, the edges of the membrane sandwiches were sealed with silicon vacuum grease.…”

Section: Methodsmentioning

confidence: 99%

“…Historical studies of the interactions of free-living amoebae and R. solani are limited. In one study, sclerotia and hyphae inoculated into soil samples showed signs of extensive predation by mycophagous protozoa [6]. Amoebae recovered from the soil were identified to be a species of Thecamoeba based on morphology.…”

Section: Introductionmentioning

confidence: 99%

Interactions of free-living amoebae with the rice fungal pathogen, Rhizoctonia solani

et al. 2019

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ObjectiveRhizoctonia solani is a soil-borne fungal pathogen of many important crop plants. In rice, R. solani causes sheath blight disease, which results in devastating grain yield and quality losses. Few methods are available to control this pathogen and classic single gene resistance mechanisms in rice plants have not been identified. We hypothesize that alternate means of control are available in the environment including free-living amoebae. Amoebae are soil-, water- and air-borne microorganisms that are predominantly heterotrophic. Many amoeba species are mycophagous, and several harm their prey using mechanisms other than phagocytosis. Here, we used light and scanning electron microscopy to survey the interactions of R. solani with four amoeba species, with the goal of identifying amoebae species with potential for biocontrol.ResultsWe observed a wide range of responses during interactions of R. solani with four different free-living amoebae. Two Acanthamoeba species encyst in co-cultures with R. solani at higher rates than medium without R. solani. Vermamoeba vermiformis (formerly Hartmanella vermiformis) attach to R. solani mycelium and are associated with mycelial shriveling and perforations of fungal cell walls, indicating an antagonistic interaction. No phenotypic changes were observed in co-cultures of Dictyostelium discoideum and R. solani.

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“…The potential of other organisms, such as protozoa, to contribute to the suppressiveness to plant pathogens in soils are poorly explored. One of the few works on this topic was done by Homma & Ishii (1984), who observed perforation on R. solani hyphae by Arachnula impatiens (amoebae). Once the predominantly protozoan groups were not identified, it was not possible to determine their contribution to pathogen suppressiveness.…”

Section: Resultsmentioning

confidence: 99%

Biotic and abiotic factors associated with soil suppressiveness to Rhizoctonia solani

Ghini¹,

Morandi²

2006

Sci. agric. (Piracicaba, Braz.)

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Crop management may modify soil characteristics, and as a consequence, alter incidence of diseases caused by soilborne pathogens. This study evaluated the suppressiveness to R. solani in 59 soil samples from a microbasin. Soil sampling areas included undisturbed forest, pasture and fallow ground areas, annual crops, perennial crops, and ploughed soil. The soil samples were characterized according to abiotic variables (pH; electrical conductivity; organic matter content; N total; P; K; Ca; Mg; Al; H; S; Na; Fe; Mn; Cu; Zn; B; cation exchange capacity; sum of bases and base saturation) and biotic variables (total microbial activity evaluated by the CO 2 evolution and fluorescein diacetate hydrolysis; culturable bacterial, fungal, actinomycetes, protozoa, fluorescent Pseudomonas and Fusarium spp. communities). The contribution and relationships of these variables to suppression to R. solani were assessed by path analysis. When all samples were analyzed together, only abiotic variables correlated with suppression of R. solani, but the entire set of variables explained only 51% of the total variation. However, when samples were grouped and analyzed by vegetation cover, the set of evaluated variables in all cases accounted for more than 90% of the variation in suppression of the pathogen. In highly suppressive soils of forest and pasture/ fallow ground areas, several abiotic variables and fluorescein diacetate hydrolysis correlated with suppression of R. solani and the set of variables explained more than 98% of suppressiveness. Key words: soilborne pathogen, soil microorganisms, biological control, path analysis, suppressive soil FATORES BIÓTICOS E ABIÓTICOS ASSOCIADOS À SUPRESSIVIDADE DE SOLOS A Rhizoctonia solaniRESUMO: As atividades agrícolas podem modificar as características do solo e, como conseqüência, alterar a incidência de patógenos veiculados pelo solo. Este trabalho avaliou a supressividade a R. solani em 59 amostras de solos de uma microbacia. As áreas amostradas foram selecionadas quanto à vegetação, incluindo mata, pasto/pousio, culturas anuais, culturas perenes e solo arado. As amostras de solo foram caracterizadas quanto às propriedades abióticas (pH, condutividade elétrica, teor de matéria orgânica, N total, P, K, Ca, Mg, Al, H, S, Na, Fe, Mn, Cu, Zn, B, capacidade de troca catiônica, soma de bases e saturação de bases) e bióticas (atividade microbiana do solo, avaliada pelo desprendimento de CO 2 e hidrólise de diacetato de fluoresceína; comunidades de bactérias, fungos, actinomicetos, protozoários, Pseudomonas fluorescentes e Fusarium spp.

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Perforation of hyphae and sclerotia of Rhizoctonia solani Kuehn by mycophagous soil amoebae from vegetable field soils in Japan.

Cited by 10 publications

References 0 publications

Shedding Light on Vampires: The Phylogeny of Vampyrellid Amoebae Revisited

Shedding Light on Vampires: The Phylogeny of Vampyrellid Amoebae Revisited

Interactions of free-living amoebae with the rice fungal pathogen, Rhizoctonia solani

Biotic and abiotic factors associated with soil suppressiveness to Rhizoctonia solani

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