Use of a Metalaxyl Tolerant Pythium Oligandrum Isolate for Selectively Following Its Population in Soil and Its Colonization of Roots of Diseased and Non-Diseased Plants

1996 ◽  
pp. 39-48 ◽  
Author(s):  
Anne Mette Madsen
Keyword(s):  
Pythium Oligandrum

scholarly journals Myco-Suppression Analysis of Soybean (Glycine max) Damping-Off Caused by Pythium aphanidermatum

Plants ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 788
Author(s):  
Shaban R. M. Sayed ◽  
Shaimaa A. M. Abdelmohsen ◽  
Hani M. A. Abdelzaher ◽  
Mohammed A. Elnaghy ◽  
Ashraf A. Mostafa ◽  
...  
Keyword(s):  
Glycine Max ◽  
Biocontrol Agent ◽  
Lateral Roots ◽  
Dry Weight ◽  
Pythium Aphanidermatum ◽  
Damping Off ◽  
Pythium Oligandrum ◽  
Rdna Its ◽  
Half Strength

The role of Pythium oligandrum as a biocontrol agent against Pythium aphanidermatum was investigated to avoid the harmful impacts of fungicides. Three isolates of P. oligandrum (MS15, MS19, and MS31) were assessed facing the plant pathogenic P. aphanidermatum the causal agent of Glycine max damping-off. The tested Pythium species were recognized according to their cultural and microscopic characterizations. The identification was confirmed through sequencing of rDNA-ITS regions including the 5.8 S rDNA. The biocontrol agent, P. oligandrum, isolates decreased the mycelial growth of the pathogenic P. aphanidermatum with 71.3%, 67.1%, and 68.7% through mycoparasitism on CMA plates. While the half-strength millipore sterilized filtrates of P. oligandrum isolates degrade the pathogenic mycelial linear growth by 34.1%, 32.5%, and 31.7%, and reduce the mycelial dry weight of the pathogenic P. aphanidermatum by 40.1%, 37.4%, and 36.8%, respectively. Scanning electron microscopy (SEM) of the most effective antagonistic P. oligandrum isolate (MS15) interaction showed coiling, haustorial parts of P. oligandrum to P. aphanidermatum hyphae. Furthermore, P. oligandrum isolates were proven to enhance the germination of Glycine max seedling to 93.3% in damping-off infection using agar pots and promote germination of up to 80% during soil pot assay. On the other hand, P. oligandrum isolates increase the shoot, root lengths, and the number of lateral roots.

scholarly journals Treatment with the Mycoparasite Pythium oligandrum Triggers Induction of Defense-Related Reactions in Tomato Roots When Challenged with Fusarium oxysporum f. sp. radicis-lycopersici

1997 ◽  
Vol 87 (1) ◽  
pp. 108-122 ◽  
Author(s):  
Nicole Benhamou ◽  
Patrice Rey ◽  
Mohamed Chérif ◽  
John Hockenhull ◽  
Yves Tirilly
Keyword(s):  
Plant Defense ◽  
Fusarium Oxysporum ◽  
Host Cell ◽  
Cell Walls ◽  
Pythium Oligandrum ◽  
Tomato Plants ◽  
Host Cytoplasm ◽  
Defense Reactions ◽  
Tomato Roots ◽  
Root Tissues

The influence exerted by the mycoparasite Pythium oligandrum in triggering plant defense reactions was investigated using an experimental system in which tomato plants were infected with the crown and root rot pathogen Fusarium oxysporum f. sp. radicis-lycopersici. To assess the antagonistic potential of P. oligandrum against F. oxysporum f. sp. radicis-lycopersici, the interaction between the two fungi was studied by scanning and transmission electron microscopy (SEM and TEM, respectively). SEM investigations of the interaction region between the fungi demonstrated that collapse and loss of turgor of F. oxysporum f. sp. radicis-lycopersici hyphae began soon after close contact was established with P. oligandrum. Ultrastructural observations confirmed that intimate contact between hyphae of P. oligandrum and cells of the pathogen resulted in a series of disturbances, including generalized disorganization of the host cytoplasm, retraction of the plasmalemma, and, finally, complete loss of the protoplasm. Cytochemical labeling of chitin with wheat germ agglutinin (WGA)/ovomucoid-gold complex showed that, except in the area of hyphal penetration, the chitin component of the host cell walls was structurally preserved at a time when the host cytoplasm had undergone complete disorganization. Interestingly, the same antagonistic process was observed in planta. The specific labeling patterns obtained with the exoglucanase-gold and WGA-ovomucoid-gold complexes confirmed that P. oligandrum successfully penetrated invading cells of the pathogen without causing substantial cell wall alterations, shown by the intense labeling of chitin. Cytological investigations of samples from P. oligandrum-inoculated tomato roots revealed that the fungus was able to colonize root tissues without inducing extensive cell damage. However, there was a novel finding concerning the structural alteration of the invading hyphae, evidenced by the frequent occurrence of empty fungal shells in root tissues. Pythium ingress in root tissues was associated with host metabolic changes, culminating in the elaboration of structural barriers at sites of potential fungal penetration. Striking differences in the extent of F. oxysporum f. sp. radicis-lycopersici colonization were observed between P. oligandrum-inoculated and control tomato plants. In control roots, the pathogen multiplied abundantly through much of the tissues, whereas in P. oligandrum-colonized roots pathogen growth was restricted to the outermost root tissues. This restricted pattern of pathogen colonization was accompanied by deposition of newly formed barriers beyond the infection sites. These host reactions appeared to be amplified compared to those seen in nonchallenged P. oligandrum-infected plants. Most hyphae of the pathogen that penetrated the epidermis exhibited considerable changes. Wall appositions contained large amounts of callose, in addition to be infiltrated with phenolic compounds. The labeling pattern obtained with gold-complexed laccase showed that phenolics were widely distributed in Fusarium-challenged P. oligandrum-inoculated tomato roots. Such compounds accumulated in the host cell walls and intercellular spaces. The wall-bound chitin component in Fusarium hyphae colonizing P. oligandrum-inoculated roots was preserved at a time when hyphae had undergone substantial degradation. These observations provide the first convincing evidence that P. oligandrum has the potential to induce plant defense reactions in addition to acting as a mycoparasite.

Influence of Pythium oligandrum on the bacterial communities that colonize the nutrient solutions and the rhizosphere of tomato plants

2012 ◽  
Vol 58 (9) ◽  
pp. 1124-1134 ◽  
Author(s):  
J. Vallance ◽  
F. Déniel ◽  
G. Barbier ◽  
L. Guerin-Dubrana ◽  
N. Benhamou ◽  
...  
Keyword(s):  
Genetic Structure ◽  
Root System ◽  
Quantitative Pcr ◽  
Bacterial Communities ◽  
Single Strand Conformation Polymorphism ◽  
Pythium Oligandrum ◽  
Tomato Plants ◽  
Cropping Season ◽  
Nutrient Solutions ◽  
Conformation Polymorphism

The influence exerted by the biocontrol oomycete Pythium oligandrum on the bacterial populations proliferating in the rhizosphere of tomato plants grown in a hydroponic system and in the circulating solutions is studied in the present experiment. Quantitative PCR and single-strand conformation polymorphism were used to investigate the genetic structure and dynamics of the bacterial communities colonizing the root systems and the various circulating solutions. Quantitative PCR assays showed that bacteria heavily colonized the rhizosphere of tomato plants with, however, no significant density changes throughout the cultural season (April–September). Single strand conformation polymorphism fingerprints revealed the occurrence of transient perturbations in the rhizospheric indigenous bacterial communities following P. oligandrum introduction in the root system of plants. This effect was, however, transient and did not persist until the end of the cropping season. Interestingly, the genetic structure of the bacterial microflora colonizing either the roots or the nutrient solutions evolved throughout the cropping season. This temporal evolution occurred whatever the presence and persistence of P. oligandrum in the rhizosphere. Evidence is also provided that bacterial microflora that colonize the root system are different from the ones colonizing the circulating solutions. The relationships between these 2 microflora (at the root and solution levels) are discussed.

scholarly journals Cytological Aspects of Compost-Mediated Induced Resistance Against Fusarium Crown and Root Rot in Tomato

2002 ◽  
Vol 92 (4) ◽  
pp. 424-438 ◽  
Author(s):  
Benoît Pharand ◽  
Odile Carisse ◽  
Nicole Benhamou
Keyword(s):  
Induced Resistance ◽  
Root Rot ◽  
Disease Incidence ◽  
Disease Suppression ◽  
Gold Complex ◽  
Peat Moss ◽  
Fungal Colonization ◽  
Pythium Oligandrum ◽  
Vascular Elements ◽  
Crown And Root Rot

The potential of a pulp and paper mill residues compost for the control of crown and root rot of greenhouse-grown tomato caused by Fusarium oxysporum f. sp. radicis-lycopersici was ultrastructurally investigated. Peat moss amended with compost substantially reduced disease-associated symptoms. Addition of Pythium oligandrum to either peat moss alone or peat moss amended with compost resulted in a considerable reduction in disease incidence compared with controls grown in peat moss alone. Histological and cytological observations of root samples from Fusarium-inoculated plants revealed that the beneficial effect of compost in reducing disease symptoms is associated with increased plant resistance to fungal colonization. One of the most prominent facets of compost-mediated induced resistance concerned the formation of physical barriers at sites of attempted fungal penetration. These structures, likely laid down to prevent pathogen ingress toward the vascular elements, included callose-enriched wall appositions and osmiophilic deposits around the sites of potential pathogen ingress. Invading hyphae, coated by the osmiophilic material, showed marked cellular disorganization. The use of the wheat germ agglutinin-ovomucoid-gold complex provided evidence that the wall-bound chitin was altered in severely damaged hyphae. A substantial increase in the extent and magnitude of the cellular changes induced by compost was observed when P. oligandrum was supplied to the potting substrate. This finding corroborates the current concept that amendment of composts with specific antagonists may be a valuable option for amplifying their beneficial properties in terms of plant disease suppression.

A novel sensitized matrix Pythium oligandrum-derived carbon for enhancement photocatalytic hydrogen evolution

2021 ◽  
Vol 284 ◽  
pp. 128939
Author(s):  
Qun Zheng ◽  
Peiya Wang ◽  
Ying Zhu ◽  
Bin Ji ◽  
Ting Mao ◽  
...  
Keyword(s):  
Hydrogen Evolution ◽  
Pythium Oligandrum ◽  
Photocatalytic Hydrogen Evolution
Sign in / Sign up

Export Citation Format

Share Document