Importance of the proportion of grassy weeds within legume crops in the perpetuation of Gaeumannomyces graminis var. tritici

Two methods (visual assessment and a bioassay) of detecting the presence of G. graminis var. tritici in wheat stubble were compared. Of the stubble visually assessed as infected, only 4 % was not confirmed as infected by the bioassay. On the other hand, the bioassay showed that 41 % of the stubble visually assessed as free of infection was incorrectly assigned.

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Isolation, Characterization, and Sensitivity to 2,4-Diacetylphloroglucinol of Isolates of Phialophora spp. from Washington Wheat Fields

Phytopathology ◽

10.1094/phyto-100-5-0404 ◽

2010 ◽

Vol 100 (5) ◽

pp. 404-414 ◽

Cited By ~ 6

Author(s):

Youn-Sig Kwak ◽

Peter A. H. M. Bakker ◽

Debora C. M. Glandorf ◽

Jennifer T. Rice ◽

Timothy C. Paulitz ◽

...

Keyword(s):

Sequence Comparison ◽

Phylogenetic Trees ◽

Washington State ◽

Gaeumannomyces Graminis ◽

Wild Oat ◽

Genetic Characteristics ◽

Oat Cultivars ◽

Eastern Washington ◽

Gaeumannomyces Graminis Var Tritici ◽

Take All

Dark pigmented fungi of the Gaeumannomyces–Phialophora complex were isolated from the roots of wheat grown in fields in eastern Washington State. These fungi were identified as Phialophora spp. on the basis of morphological and genetic characteristics. The isolates produced lobed hyphopodia on wheat coleoptiles, phialides, and hyaline phialospores. Sequence comparison of internal transcribed spacer regions indicated that the Phialophora isolates were clearly separated from other Gaeumannomyces spp. Primers AV1 and AV3 amplified 1.3-kb portions of an avenacinase-like gene in the Phialophora isolates. Phylogenetic trees of the avenacinase-like gene in the Phialophora spp. also clearly separated them from other Gaeumannomyces spp. The Phialophora isolates were moderately virulent on wheat and barley and produced confined black lesions on the roots of wild oat and two oat cultivars. Among isolates tested for their sensitivity to 2,4-diacetylphloroglucinol (2,4-DAPG), the 90% effective dose values were 11.9 to 48.2 μg ml–1. A representative Phialophora isolate reduced the severity of take-all on wheat caused by two different isolates of Gaeumannomyces graminis var. tritici. To our knowledge, this study provides the first report of an avenacinase-like gene in Phialophora spp. and demonstrated that the fungus is significantly less sensitive to 2,4-DAPG than G. graminis var. tritici.

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Gaeumannomyces graminis var. tritici. [Descriptions of Fungi and Bacteria].

IMI Descriptions of Fungi and Bacteria ◽

10.1079/dfb/20056400383 ◽

1973 ◽

Author(s):

J. Walker

Keyword(s):

Geographical Distribution ◽

Root Hairs ◽

Seed Transmission ◽

Gaeumannomyces Graminis ◽

Root Infection ◽

Root Death ◽

Meristematic Region ◽

Germ Tubes ◽

Gaeumannomyces Graminis Var Tritici ◽

Take All

Abstract A description is provided for Gaeumannomyces graminis var. tritici. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Gramineae, especially Triticum, Hordeum, Secale, Agropyron and several other grass genera and, more rarely, Sorghum and Zea; also recorded from the roots of plants in other families. DISEASE: Take-all of cereals and grasses (also referred to as deadheads or whiteheads, pietin and pied noir (France), Schwarzbeinigkeit and Ophiobolus Fusskrankheit (Germany), Ophiobolusvoetziekt (Netherlands) and others). Root infection is favoured by soil temperature from 12-20°C (Butler, 1961). Ascospore germ tubes penetrate root hairs and the epidermis in the meristematic region (Weste, 1972) leading to plugging of xylem and root death. GEOGRAPHICAL DISTRIBUTION: (CMI Map 334, ed. 3, 1972). Widespread, especially in temperate zones. Africa; Asia (India, Iran, Japan, USSR): Australasia and Oceania; Europe; North America (Canada, USA); South America (Argentina, Brazil, Chile, Colombia, Uruguay). TRANSMISSION: In soil on infected organic fragments, as runner hyphae on roots of cereals and grasses and, under special conditions, by ascospores. Seed transmission very doubtful (47, 3058).

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