Disease suppression by the ectomycorrhizal fungus Paxillus involutus: contribution of oxalic acid

1989 ◽  
Vol 67 (9) ◽  
pp. 2726-2730 ◽  
Author(s):  
Luc C. Duchesne ◽  
Brian E. Ellis ◽  
R. L. Peterson
Keyword(s):  
Oxalic Acid ◽  
Root Rot ◽  
High Performance ◽  
Root Exudate ◽  
Gel Filtration ◽  
Pinus Resinosa ◽  
Fold Increase ◽  
Ectomycorrhizal Fungus ◽  
Disease Suppression ◽  
Paxillus Involutus

Seedlings of Pinus resinosa Ait. grown in test tubes were inoculated with the ectomycorrhizal fungus Paxillus involutus Fr. Oxalic acid was identified as one of the ethanol-soluble fungistatic and (or) fungitoxic components of the rhizosphere after fractionation by high performance liquid chromatography, paper chromatography, and gel filtration. Simultaneous inoculation of P. resinosa seedlings with authentic oxalic acid and a spore suspension of Fusarium oxysporum f.sp. pini protected the seedlings against Fusarium root rot and decreased the sporulation of F. oxysporum in the rhizosphere when compared with controls lacking oxalic acid. Quantitation of oxalic acid showed a five fold increase in production by Pax. involutus in tubes containing P. resinosa seedlings when compared with tubes lacking seedlings. The synthesis of oxalic acid by Pax. involutus is, therefore, stimulated by P. resinosa root exudate.

Early effects of the ectomycorrhizal fungus Paxillus involutus on the root rot organism Fusarium associated with Pinus resinosa

1990 ◽  
Vol 68 (7) ◽  
pp. 1589-1596 ◽  
Author(s):  
M. L. Farquhar ◽  
R. L. Peterson
Keyword(s):  
Pinus Resinosa ◽  
Ectomycorrhizal Fungus ◽  
Test Tube ◽  
Disease Suppression ◽  
Wall Material ◽  
Paxillus Involutus ◽  
Calcofluor White ◽  
Cytoplasmic Inclusions ◽  
Early Effects ◽  
Root Tissues

Infection of Pinus resinosa Ait. seedlings in a sterile test tube culture system by Fusarium oxysporum f.sp. pini Schlecht. emend. Snyd. & Hans., which was determined microscopically by the presence of the fungus within root tissues, was significantly reduced within the first 6 days of infection after prior inoculation with the ectomycorrhizal fungus Paxillus involutus (Batsch) Fr. Hyphae and conidia of the pathogen were swollen and filled with osmiophilic material when P. involutus was also present in the rhizosphere of P. resinosa seedlings. Germination of F. oxysporum conidia was suppressed when they were placed in holes in P. involutus cultures on modified Melin Norkrans medium in Petri plates but was restored with removal of conidia from plates. Suppressed, ungerminated conidia had thick cell walls and large cytoplasmic inclusions. Staining using Calcofluor White M2R New revealed changes in the binding properties of septal wall material. Key words: Paxillus, Fusarium, ectomycorrhiza, disease suppression, anatomy.

Interaction between the ectomycorrhizal fungus Paxillus involutus and Pinus resinosa induces resistance to Fusarium oxysporum

1988 ◽  
Vol 66 (3) ◽  
pp. 558-562 ◽  
Author(s):  
Luc C. Duchesne ◽  
R. L. Peterson ◽  
Brian E. Ellis
Keyword(s):  
Fusarium Oxysporum ◽  
Seedling Survival ◽  
Pathogenic Fungus ◽  
Pinus Resinosa ◽  
Ectomycorrhizal Fungus ◽  
Antibiotic Activity ◽  
Disease Suppression ◽  
Paxillus Involutus ◽  
Subsequent Infection ◽  
Fivefold Increase

Inoculation of Pinus resinosa Ait. seedlings with the ectomycorrhizal fungus Paxillus involutus Fr. resulted in a 47% increase in resistance to subsequent infection by the root pathogenic fungus Fusarium oxysporum f.sp. pini as compared with control seedlings. This increase in seedling survival was associated with a sixfold decrease in the sporulation of F. oxysporum in the rhizosphere of seedlings inoculated with Pax. involutus when compared with the rhizosphere of control seedlings. Extraction and bioassay of the seedling rhizosphere and seedling tissues indicated that inoculation with Pax. involutus led to a fivefold increase in antibiotic activity in the rhizosphere of the seedlings treated with Pax. involutus. Most or all of the fungitoxicity was localized in the rhizosphere. Disease suppression by Pax. involutus in P. resinosa is, therefore, associated with an increase of fungitoxic chemicals in the rhizosphere of seedlings.

Later events in suppression of Fusarium root rot of red pine seedlings by the ectomycorrhizal fungus Paxillus involutus

1991 ◽  
Vol 69 (6) ◽  
pp. 1372-1383 ◽  
Author(s):  
M. L. Farquhar ◽  
R. L. Peterson
Keyword(s):  
Pinus Resinosa ◽  
Ectomycorrhizal Fungus ◽  
Red Pine ◽  
Disease Suppression ◽  
Host Cells ◽  
Paxillus Involutus ◽  
Free System ◽  
Primary Roots ◽  
Pine Seedlings ◽  
Rooting Medium

Colonization of primary roots of red pine (Pinus resinosa Ait.) seedlings by two isolates of the fungal pathogen Fusarium oxysporum Schlecht. emend Snyd. & Hans. f.sp. pini in a sterile, soil-free system and a nonsterile rooting medium was suppressed for 2 months if the roots were exposed to the ectomycorrhizal fungus Paxillus involutus (Batsch.) Fr. for 1 week before being inoculated with the pathogen. Roots of protected seedlings harboured only a few hyphae of the pathogen. These were either vacuolated or filled with slightly electron-dense substances and did not penetrate host cells. In contrast, roots of seedlings not inoculated by P. involutus were extensively colonized by F. oxysporum, and host tissue vacuolation and disorganization occurred. Papillae, consisting of either small protuberances or elongate projections, were infrequently formed in response to infection. Chlamydospores of F. oxysporum that formed in the sterile system had numerous lipid deposits and amorphous thick walls but few mitochondria and little endoplasmic reticulum. Key words: biological control, ectomycorrhiza, Fusarium, Pinus resinosa, disease suppression.

scholarly journals Cadmium-Responsive Thiols in the Ectomycorrhizal Fungus Paxillus involutus

2004 ◽  
Vol 70 (12) ◽  
pp. 7413-7417 ◽  
Author(s):  
Mikael Courbot ◽  
Laurent Diez ◽  
Roberta Ruotolo ◽  
Michel Chalot ◽  
Pierre Leroy
Keyword(s):  
Molecular Mass ◽  
Ectomycorrhizal Fungi ◽  
High Performance ◽  
Metal Tolerance ◽  
Ectomycorrhizal Fungus ◽  
Paxillus Involutus ◽  
Cellular Mechanisms ◽  
Chromatography Method ◽  
Relative Lack ◽  
Liquid Chromatography Method

ABSTRACT Molecular and cellular mechanisms underlying the sustained metal tolerance of ectomycorrhizal fungi are largely unknown. Some of the main mechanisms involved in metal detoxification appear to involve the chelation of metal ions in the cytosol with thiol-containing compounds, such as glutathione, phytochelatins, or metallothioneins. We used an improved high-performance liquid chromatography method for the simultaneous measurement of thiol-containing compounds from cysteine and its derivatives (γ-glutamylcysteine, glutathione) to higher-molecular-mass compounds (phytochelatins). We found that glutathione and γ-glutamylcysteine contents increased when the ectomycorrhizal fungus Paxillus involutus was exposed to cadmium. An additional compound with a 3-kDa molecular mass, most probably related to a metallothionein, increased drastically in mycelia exposed to cadmium. The relative lack of phytochelatins and the presence of a putative metallothionein suggest that ectomycorrhizal fungi may use a different means to tolerate heavy metals, such as Cd, than do their plant hosts.

Aspartic Proteinase in Dugesia tigrina (Girard) Planaria

2002 ◽  
Vol 57 (5-6) ◽  
pp. 541-547 ◽  
Author(s):  
Fanny B. Zamora-Veyl ◽  
Herbert L. M. Guedes ◽  
Salvatore Giovanni-De-Simone
Keyword(s):  
High Performance ◽  
Specific Activity ◽  
Ph Value ◽  
Cysteine Proteinase ◽  
Gel Filtration ◽  
Fold Increase ◽  
Maximal Activity ◽  
Single Step ◽  
Dugesia Tigrina ◽  
Final Yield

A proteolytic activity was identified in Dugesia tigrina planaria using the chromogenic substrate Phe-Ala-Ala-Phe (4-NO2)-Phe-Val-Leu-O4MP. The activity of the enzyme increased four times during the regeneration and presented a maximum at 120 hr being higher in tail than head regenerating segments. The protease that displays this activity was purified from worms by a single step on pepstatin-agarose followed by gel-filtration high performance liquid chromatography. The purification resulted in a 34-fold increase in specific activity and the final yield was 10%. The active D. tigrina hydrolase appears to be a dimeric protein composed of identical subunits with 34 kDa associated by disulphide bridges similar to vertebrate cathepsin D. By SDS-PAGE several bands were detected but upon gel filtration HPLC one proteolytically active component, termed Asp-68, was detected and isolated. The maximal activity was observed in a range between pH 3.5-5.0 and the enzyme became inactivated at a pH value above 7.2. The purified enzyme was not inhibited by inhibitors from serine (aprotinin, TPCK, PMSF and TLCK), metallo (EDTA) and cysteine proteinase (E-64) classes. In contrast, inhibitors such as pepstatin, EPNP, and 4-β-PMA efficiently inhibited the activity of the 68-kDa protease.

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