scholarly journals Effect of Wheat Roots Infected with the Pathogenic Fungus Gaeumannomyces graminis var. tritici on Gene Expression of the Biocontrol Bacterium Pseudomonas fluorescens Pf29Arp

2009 ◽  
Vol 22 (12) ◽  
pp. 1611-1623 ◽  
Author(s):  
Matthieu Barret ◽  
Pascale Frey-Klett ◽  
Anne-Yvonne Guillerm-Erckelboudt ◽  
Morgane Boutin ◽  
Gregory Guernec ◽  
...  
Keyword(s):  
Gene Expression ◽  
Pseudomonas Fluorescens ◽  
Pathogenic Fungus ◽  
Pathogenic Fungi ◽  
Gaeumannomyces Graminis ◽  
Type Vi Secretion System ◽  
Gene Encoding ◽  
Wheat Roots ◽  
Gaeumannomyces Graminis Var Tritici ◽  
Biocontrol Bacterium

Traits contributing to the competence of biocontrol bacteria to colonize plant roots are often induced in the rhizosphere in response to plant components. These interactions have been studied using the two partners in gnotobiotic systems. However, in nature, beneficial or pathogenic fungi often colonize roots. Influence of these plant–fungus interactions on bacterial behavior remains to be investigated. Here, we have examined the influence of colonization of wheat roots by the take-all fungus Gaeumannomyces graminis var. tritici on gene expression of the biocontrol bacterium Pseudomonas fluorescens Pf29Arp. Bacteria were inoculated onto healthy, early G. graminis var. tritici-colonized and necrotic roots and transcriptomes were compared by shotgun DNA microarray. Pf29Arp decreased disease severity when inoculated before the onset of necrosis. Necrotic roots exerted a broader effect on gene expression compared with early G. graminis var. tritici-colonized and healthy roots. A gene encoding a putative type VI secretion system effector was only induced in necrotic conditions. A common pool of Pf29Arp genes differentially expressed on G. graminis var. tritici-colonized roots was related to carbon metabolism and oxidative stress, with a highest fold-change with necrosis. Overall, the data showed that the association of the pathogenic fungus with the roots strongly altered Pf29Arp adaptation with differences between early and late G. graminis var. tritici infection steps.

scholarly journals Identification of Cryptococcus neoformans Temperature-Regulated Genes with a Genomic-DNA Microarray

2004 ◽  
Vol 3 (5) ◽  
pp. 1249-1260 ◽  
Author(s):  
Peter R. Kraus ◽  
Marie-Josée Boily ◽  
Steven S. Giles ◽  
Jason E. Stajich ◽  
Andria Allen ◽  
...  
Keyword(s):  
Gene Expression ◽  
High Temperature ◽  
Cryptococcus Neoformans ◽  
Stress Responses ◽  
Pathogenic Fungus ◽  
High Growth ◽  
Synthesis Inhibitor ◽  
Gene Encoding ◽  
Temperature Growth ◽  
Partial Genome

ABSTRACT The ability to survive and proliferate at 37°C is an essential virulence attribute of pathogenic microorganisms. A partial-genome microarray was used to profile gene expression in the human-pathogenic fungus Cryptococcus neoformans during growth at 37°C. Genes with orthologs involved in stress responses were induced during growth at 37°C, suggesting that a conserved transcriptional program is used by C. neoformans to alter gene expression during stressful conditions. A gene encoding the transcription factor homolog Mga2 was induced at 37°C and found to be important for high-temperature growth. Genes encoding fatty acid biosynthetic enzymes were identified as potential targets of Mga2, suggesting that membrane remodeling is an important component of adaptation to high growth temperatures. mga2Δ mutants were extremely sensitive to the ergosterol synthesis inhibitor fluconazole, indicating a coordination of the synthesis of membrane component precursors. Unexpectedly, genes involved in amino acid and pyrimidine biosynthesis were repressed at 37°C, but components of these pathways were found to be required for high-temperature growth. Our findings demonstrate the utility of even partial-genome microarrays for delineating regulatory cascades that contribute to microbial pathogenesis.

scholarly journals Evidence of a Multicopper Oxidase in Mn Oxidation by Gaeumannomyces graminis var. tritici

2006 ◽  
Vol 96 (2) ◽  
pp. 130-136 ◽  
Author(s):  
Ian A. Thompson ◽  
Don M. Huber ◽  
Darrell G. Schulze
Keyword(s):  
Molecular Weight ◽  
Laccase Activity ◽  
Pathogenic Fungus ◽  
Extracellular Enzyme ◽  
Multicopper Oxidase ◽  
Gaeumannomyces Graminis ◽  
Multicopper Oxidases ◽  
Cellulose Acetate Electrophoresis ◽  
Gaeumannomyces Graminis Var Tritici ◽  
Take All

Manganese (Mn) oxidation by the plant-pathogenic fungus Gaeumannomyces graminis var. tritici has been correlated with virulence in take-all disease. The mechanism of Mn oxidation has not, however, been investigated adequately. Research on bacteria and other fungi indicates that Mn oxidation is most often the result of the activity of multicopper oxidases. To determine if G. graminis var. tritici oxidizes Mn by similar means, the Mn oxidizing factor (MOF) produced by G. graminis var. tritici was characterized by cultural, spectrophotometric, and cellulose acetate electrophoresis methods. Based on our results, the MOF is an extracellular enzyme with an estimated molecular weight of 50 to 100 kDa. Electrophoresis and spectrophotometry indicate that the MOF is a multicopper oxidase with laccase activity.

scholarly journals In vitro Antagonistic Mechanisms of Trichoderma spp. and Talaromyces flavus to Control Gaeumannomyces graminis var. tritici the Causal Agent of Wheat Take-all Disease

2015 ◽  
Vol 3 (8) ◽  
pp. 629
Author(s):  
Seddighe Mohammadi ◽  
Leila Ghanbari
Keyword(s):  
Pathogenic Fungus ◽  
Causal Agent ◽  
Gaeumannomyces Graminis ◽  
Dual Culture ◽  
Mycelium Growth ◽  
Trichoderma Spp ◽  
Talaromyces Flavus ◽  
Gaeumannomyces Graminis Var Tritici ◽  
Take All

Wheat take-all disease caused by Gaeumannomyces graminis var. tritici has recently been detected in different regions of Iran. With respect to biocontrol effect of Trichoderma spp. on many pathogenic fungi, seven isolates of Trichoderma and four isolates of Talaromyces were in vitro evaluated in terms of their biological control against the disease causal agent. In dual culture test the five isolates showed efficient competition for colonization against pathogenic fungus and the highest percentages of inhibition belonging to Talaromyces flavus 60 and Talaromyces flavus 136 were 59.52 and 57.61%, respectively. Microscopic investigations showed that in regions where antagonistic isolates and Gaeumannomyces graminis var. tritici coincide, hyphal contact, penetration and fragmentation of Gaeumannomyces graminis var. tritici were observed. Investigating the effect of volatile and non-volatile compounds at 10 ml concentration showed that the highest inhibition percentage on mycelium growth of the pathogen caused by T. harzianum (44.76%) and T. longibrachiatum (52.38%) respectively.

scholarly journals Functional characteristics of New Zealand wheat rhizosphere Pseudomonas fluorescens isolates and their potential to inhibit invitro growth of Gaeumannomyces graminis var tritici

2016 ◽  
Vol 69 ◽  
pp. 48-56
Author(s):  
R.M. Warren ◽  
S.F. Chng ◽  
R.C. Butler
Keyword(s):  
New Zealand ◽  
Pseudomonas Fluorescens ◽  
Plant Pathogens ◽  
Gaeumannomyces Graminis ◽  
Pcr Analysis ◽  
Direct Stimulation ◽  
Soilborne Disease ◽  
Biochemical Assays ◽  
Dual Plate ◽  
Gaeumannomyces Graminis Var Tritici

Pseudomonas fluorescens are soilinhabiting plant growthpromoting rhizobacteria (PGPR) linked with suppression of takeall of wheat a soilborne disease caused by Gaeumannomyces graminis var tritici (Ggt) PGPR increase plant growth by direct stimulation producing metabolites (such as 24diacetylphloroglucinol 24DAPG) to inhibit plant pathogens or by inducing host defence mechanisms Fortythree New Zealand P fluorescens isolates collected from wheat rhizospheres of different cropping histories were characterised for secondary metabolite production using biochemical assays and PCR analysis Their ability to inhibit the growth of Ggt was determined in dual plate assays All of the bacterial isolates produced siderophores and 10 isolates produced hydrogen cyanide (HCN) However none of the isolates produced indole acetic acid and the phlD gene responsible for the production of 24DAPG was not detected Isolates that showed at least 60 inhibition of Ggt growth were found to produce either HCN or high levels of siderophore The results suggest HCN and siderophores could play a role in suppressing Ggt and managing takeall in New Zealand

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