scholarly journals Effects of Pseudomonas fluorescens CHA0 on the Resistance of Wheat Seedling Roots to the Take-all Fungus Gaeumannomyces graminis var. tritici

2008 ◽  
Vol 11 (3) ◽  
pp. 298-306 ◽  
Author(s):  
Ehsan Sari ◽  
Hassan Reza Etebarian ◽  
Heshmatollah Aminian
1996 ◽  
Vol 44 (4) ◽  
pp. 499 ◽  
Author(s):  
S Seah ◽  
K Sivasithamparam ◽  
DW Turner

The effect of salicylic acid (SA) applied as foliar dip, foliar wipe, root drench or pre-germination soak on the susceptibility of wheat (Triticum aestivum L.) seedlings to Gaeumannomyces graminis (Sacc.) Arx & Olivier var. tritici Walker (take-all fungus, Ggt) was studied. It was hypothesised that an increase in SA concentration applied using these methods would increase the resistance in wheat seedling roots against Ggt. Leaves (by foliar wipe and foliar dip) and roots (by root drench) of 1-2-week-old wheat seedlings grown in Lancelin sand, were treated with 0, 0.1 or 1 mM SA, and treatments of 0, 0.1 or 0.5 mM SA were applied in a pre-germination soak method. Ggt infection reduced (P Ͱ4 0.05) chlorophyll content and concentration and root length (P Ͱ4 0.10). Experiments that were conducted suggested that the SA treatments failed to induce a resistance response because they did not stimulate phenylalanine ammonia-lyase and peroxidase activities in the wheat seedling roots. Therefore, SA applied using these methods was not effective in reducing the susceptibility of wheat seedlings to Ggt. The chemical or biological induction of resistance in plant roots and its applicability as a root disease control strategy requires further clarification.


1979 ◽  
Vol 93 (2) ◽  
pp. 377-389 ◽  
Author(s):  
D. B. Slope ◽  
R. D. Prew ◽  
R. J. Gutteridge ◽  
Judith Etheridge

SUMMARYThe Rothamsted ley–arable experiments were on two fields with similar soils but with contrasting previous cropping: old grass on Highfield, old arable on Fosters field. Damage by take-all (Qaeumannomyces graminis var. tritici) occurred sooner in successive wheat crops grown after a lucerne ley and arable sequence (LU) than after a grass-clover ley and arable sequence (LC). On Highfield the difference was consistent and large, it occurred as soon as a second wheat crop was grown and resulted in wheat yielding 1 t/ha less after the LU than after the LC sequence. This difference did not persist in the next wheat crop where take-all was prevalent after both sequences. On Fosters field take-all developed more slowly and differences between sequences were mostly smaller.Wheat seedling bio-assay of soil cores from the LU and LC sequences showed that little take-all fungus persisted through the leys and that soils were much infested after a first wheat crop in the LU sequence on Highfield, but not in the LC sequence on Highfield or in either sequence on Fosters field. Microscopic examination of roots from assay seedlings and from field plants showed that Phialophora radicicola var. graminicola (PRG) was most common in soils where take-all developed slowly, but our results did not show if this was a causal relationship. The occurrence of much PRG in the LU sequence on Fosters conflicts with previous reports which associate large populations of this fungus only with grassland soils.


2017 ◽  
Vol 70 ◽  
pp. 186-195
Author(s):  
R.F. Van Toor ◽  
S.F. Chng ◽  
R.M. Warren ◽  
R.C. Butler

Couch grass rhizomes harbour Gaeumannomyces graminis var. tritici (Ggt), which causes take-all of wheat. Glyphosate used after cereal harvest to control couch can increase take- all in subsequent wheat crops. Following glyphosate treatment, the colonisation of senescing couch rhizomes by Ggt when treated with the endophytic fungus Microdochium bolleyi, and the spread of Ggt from senescing couch rhizomes to wheat when treated with the rhizobacterium Pseudomonas fluorescens, were investigated in two separate experiments. In Experiment 1, glyphosate increased Ggt inoculum in couch, irrespective of whether M. bolleyi was added to the potting medium. In Experiment 2, take-all severity and Ggt DNA concentration in roots of the accompanying wheat plants tended to decrease with glyphosate treatment of couch and increase only when P. fluorescens was added. Soil-borne microflora in fields containing glyphosate-sprayed couch may affect expression of take-all in subsequent wheat.


2010 ◽  
Vol 100 (5) ◽  
pp. 404-414 ◽  
Author(s):  
Youn-Sig Kwak ◽  
Peter A. H. M. Bakker ◽  
Debora C. M. Glandorf ◽  
Jennifer T. Rice ◽  
Timothy C. Paulitz ◽  
...  

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.


Author(s):  
J. Walker

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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