Search results for "antibiosis"

Pythium perplexum isolated from soil in France: morphology, molecular characterisation and biological control.

2001

Pythium perplexum (F-926) was isolated from a soil sample taken in the Burgundy region in France. In 1907, it was mistakenly described by Bulter as P. vexans. Despite morphological resemblance, the comparison between the internal transcribed spacer 1 regions of the ribosomal DNA of the two fungi leaves no doubt of their different identities. P. perplexum was found to be highly pathogenic to cucumber seedlings. Damping-off disease of cucumber caused by P. perplexum can effectively be controlled by using the soil bacterium Serratia plymuthica (B-781). The details of the morphology and the molecular characterisation of P. perplexum and its biological control with S. plymuthica are described he…

Characterization of field isolates of Trichoderma antagonistic against Rhizoctonia solani.

2010

The aim of the present study was to characterize sixteen isolates of Trichoderma originating from a field of sugar beet where disease patches caused by Rhizoctonia solani were observed. Use of both molecular and morphological characteristics gave consistent identification of the isolates. Production of water-soluble and volatile inhibitors, mycoparasitism and induced systemic resistance in plant host were investigated using in vitro and in vivo tests in both sterilized and natural soils. This functional approach revealed the intra-specific diversity as well as biocontrol potential of the different isolates. Different antagonistic mechanisms were evident for different strains. The most antag…

Characterization of field isolates of Trichoderma antagonistic towards Rhizoctonia solani

2009

Rhizoctonia solani AG 2-2 is a phytopathogenic fungus causing damping off and root rot in sugar beet. The disease occurs in the form of patches. In monoculture, these patches are highly mobile and never occur at the same place where they were observed the previous year. The soil from within patches was found more suppressive towards the disease than soil from healthy area. Comparison of the microbial genetic structures between the different soil samples suggested that Trichoderma spp. were involved in the increased suppressiveness. Trichoderma spp. are well known for their antagonistic activities. The aim of the present study was to characterize sixteen Trichoderma isolates isolated from wi…

Antagonistic activity of Bacillus subtilis strain AG1 against fungal microorganisms associated with Vitis vinifera.

2009

Antibiosis as a possible mechanism of soil suppressiveness to Fusarium wilts

2008

ITS region of Pythium canariense sp. nov., its morphology and its interaction with Botrytis cinerea.

2002

A new species Pythium canariense (CI-07), isolated from soil samples taken in the San Nicolas region of the Canary islands (Gran Canaria, Spain), is being described here. This species is characterised by its spherical to pyriform, intercalary to catenulate sporangia, smooth-walled terminal oogonia supplied with monoclinous and diclinous antheridia which at times are branched and wrap around the female gametangia. The fungus has an antagonistic effect on Botrytis cinerea, the grey mould fungus. Morphological features are being given here together with the sequence of the complete internal transcribed spacer region of the nuclear ribosomal DNA of the fungus, its comparison with related specie…

Phenazine antibiotics produced by fluorescent pseudomonads contribute to natural soil suppressiveness to Fusarium wilt

2009

Natural disease-suppressive soils provide an untapped resource for the discovery of novel beneficial microorganisms and traits. For most suppressive soils, however, the consortia of microorganisms and mechanisms involved in pathogen control are unknown. To date, soil suppressiveness to Fusarium wilt disease has been ascribed to carbon and iron competition between pathogenic Fusarium oxysporum and resident non-pathogenic F. oxysporum and fluorescent pseudomonads. In this study, the role of bacterial antibiosis in Fusarium wilt suppressiveness was assessed by comparing the densities, diversity and activity of fluorescent Pseudomonas species producing 2,4-diacetylphloroglucinol (DAPG) (phlD+) …

Characterisation of Pythium paroecandrum and its antagonism towards Botrytis cinerea, the causative agent of grey mould disease of grape.

2004

Pythium paroecandrum (B-30), an oomycete, was isolated from soil samples taken from a wheat field in Genlis in the Burgundy region of France and was found to check the growth and development of Botrytis cinerea, a serious grapevine pathogen. The oomycete is a fast-growing organism, living on vegetable debris, and can be recognised by its catenulate hyphal swellings, catenulate oogonia, and monoclinous antheridia. When grown together with B. cinerea, the causal agent of the grey mould disease of the grapevine, P. paroecandrum shows a pronounced antagonism and suppresses its growth and its aptitude to provoke the grey mould symptoms. Morphological features of this oomycete, its antagonism to …

A new mycoparasite, Pythium lycopersicum, isolated in Isparta, Turkey: morphology, molecular characteristics, and its antagonism with phytopathogenic…

2008

Pythium lycopersicum sp. nov. has been isolated from soil samples taken in an agricultural land in the Isparta region of Southern Turkey. This oomycete is characterized by its contiguous sporangia having globose to elongated elements linked with hyphal filaments, ornamented oogonia, and monoclinous antheridia with large antheridial cells. The oomycete is reminiscent of Pythium ornamentatum described by the corresponding author in 1987 from soil samples taken in Algeria. Sequence analyses of the internal transcribed spacer (ITS) regions of rRNA show a close relationship with Pythium oligandrum and other mycoparasites possessing ornamented oogonia. Morphological and molecular features of this…

Pythium contiguanum nomen novum (syn. Pythium dreschleri Paul), its antagonism to Botrytis cinerea, ITS1 region of its nuclear ribosomal DNA, and its…

2000

Pythium drechsleri Paul was described as a new species from soil samples taken in a salt-marsh of Arzew, Algeria [Paul, B. (1988) Une nouvelle espece de Pythium isolee d'une saline de l'ouest Algerien. Cryptogam. Mycol. 9, 325-333]. The name of the fungus, P. drechsleri, is a nomen invalidum, as it is a later homonym of P. drechsleri Rajgopalan and Ramakrishnan [Rajagopalan, S. and Ramakrishnan, K. (1971) Phycomycetes in agricultural soils with special reference to the Pythiaceae. Madras Univ. J. Sect. B 37,38, 100-117]. A new name, Pythium contiguanum is now being given to P. drechsleri Paul. This species is characterised by its contiguous inflated type of sporangia, smooth-walled oogonia …