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Pythium aphanidermatum

About: Pythium aphanidermatum is a research topic. Over the lifetime, 906 publications have been published within this topic receiving 16711 citations.


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Journal ArticleDOI
TL;DR: The results suggest that the plant defense enzymes could be stimulated in cucumber roots which have been colonized by non-pathogenic rhizobacteria or in a compatible interaction between cucumber and P. aphanidermatum.

547 citations

Journal ArticleDOI
TL;DR: The role of silicon (Si) in plant growth was investigated on the basis of induction of defense mechanisms in response to fungal attacks and glycosidically bound phenolics extracted from Si+ plants and subjected to acid or β-glucosidase hydrolysis displayed a strong fungistatic activity.
Abstract: The role of silicon (Si) in plant growth was investigated on the basis of induction of defense mechanisms in response to fungal attacks Amendment of cucumber plants with soluble Si (Si+) resulted in a marked stimulation of chitinase activity and in a more intense and rapid activation of peroxidases and polyphenoloxidases after infection with Pythium spp Additionally, glycosidically bound phenolics extracted from Si+ plants and subjected to acid or β-glucosidase hydrolysis (Gly extracts) displayed a strong fungistatic activity against P ultimum, P aphanidermatum, and Cladosporium cucumerinum Extracts obtained in the same way from control plants were not inhibitory to fungal growth, regardless of Si treatment []

388 citations

Journal ArticleDOI
TL;DR: Results suggest that proteins in the cell walls of F. oxysporum may make these walls more resistant than those of R. solani or S. rolfsii to degradation by extracellular enzymes of T. harzianum.
Abstract: SUMMARY: In in vitro tests, two strains of Trichoderma harzianum failed to parasitize colonies of Fusarium oxysporum f. sp. vasinfectum and F. oxysporum f. sp. melonis. However, these strains were strongly mycoparasitic on Rhizoctonia solani and Pythium aphanidermatum. When grown in liquid cultures containing laminarin, chitin or fungal cell walls as sole carbon sources, both strains of T. harzianum released, 3-β-glucanase and chitinase into the medium. Higher levels of these enzymes were induced in strain T-203 than in T-35 by hyphal cell walls of F. oxysporum. When the lytic enzymes produced by T-35 were incubated with hyphal cell walls of the test fungi, more glucose and N-acetyl-d-glucosamine was released from cell walls of R. solani and Sclerotium rolfsii than from those of F. oxysporum. Treatment of F. oxysporum cell walls with 2 m-NaOH, protease or trypsin prior to their incubation with the lytic enzymes of T. harzianum significantly increased the release of glucose and N-acetyl-d-glucosamine. The effect of these treatments on R. solani and S. rolfsii cell walls was much lower. These results suggest that proteins in the cell walls of F. oxysporum may make these walls more resistant than those of R. solani or S. rolfsii to degradation by extracellular enzymes of T. harzianum.

265 citations

Journal ArticleDOI
TL;DR: Of the 130 bacteria isolated from the rhizospheres of plants infested with application or seed coating with these bacteria reduced disease incidence in Pythium spp.
Abstract: Elad, Y., and Chet, 1. 1987. Possible role of competition for nutrients in biocontrol of Pythium damping-off by bacteria. Phytopathology 77:190-195. Of the 130 bacteria isolated from the rhizospheres of plants infested with application or seed coating with these bacteria reduced disease incidence in Pythium spp., six were found to be efficient biocontrol agents of this cucumbers planted in peat-vermiculite mixture or in soil by 60-75% pathogen under greenhouse conditions. No lytic enzymes were involved in compared with the untreated control. Damping-off caused by P. ultimum in vitro interactions between the bacteria and P. aphanidermatum. in cucumbers was reduced by up to 94%. Combining low levels of Substances inhibiting growth of the fungus were produced by both the Pseudomonasputida or P. cepacia with the fungicide prothiocarb resulted biocontrol agents and other rhizobacteria. On the other hand, competition in an additive effect. Bacteria applied to cucumber seeds became for nutrients between germinating oospores of P. aphanidermatum and established along the roots. Populations were 100-fold higher at root tips bacteria, which was unique to the biocontrol agents, significantly than at their upper parts. On the other hand, except for the root tips, the correlated with suppression of disease in the greenhouse. Oospore total population of bacteria was decreased in the presence of the beneficial germination in rhizospheres of wheat, tomato, cucumber, melon, bean, and ones. Disease control was achieved in bean, pepper, melon, tomato, and cotton plants was decreased in the presence of these bacteria. Broadcast cotton plants as well. Rhizobacteria, by their interactions with various pathogens, les Grottes 38390, Montalieu, Vercieu, France). Identification was play a major role in the biological equilibrium among verified by Bergey's Manual of Determinative Bacteriology. The microorganisms in the rhizosphere (1,23). Pythium spp. have a following strains were used: Pseudomonasputida (Trev.) Migula broad host range and cause preemergence and postemergence (805 and 310), P. cepacia Burk (808, 814, and Yl I), Alcaligens damping-off and root rots followed by considerable yield losses in Cast. & Chal. sp. (Rh2), and Pseudomonas (Migula) Doud & Pall. many important crops. sp. (AA4, SS3, and 806). Cultures were maintained on NA for daily Biological control of this pathogen with bacteria is not well use. Pure cultures were grown on NA for 24 hr, washed from the established. Mitchell and Hurvitz (15) protected tomato seedlings agar surface with 10% skimmed milk, and freeze-dried. against damping-off caused by P. debaryanum Hesse with a lytic Density of bacterial populations. Strains of the biocontrol strain of A rthrobacter, and Hadar et al (7) protected germinating agents resistant to rifampicin [3-(4-methylpiperazinyl-minomerhyl) cucumber seeds with Enterobacter cloacae (Jordan) Harm & rifamycin 5v) and nalidixic acid (Sigma) were selected from parent Edwar from rots caused by Pythium spp. Howell and Stipanovic cultures by planting cell suspensions on NA containing 150 /tg/ ml (9) isolated a strain of Pseudomonas fluorescens Migula that rifampicin [3-(4-methylpiperazinyl-iminomethyl) rifamycin] and produces an antibiotic inhibiting growth of Pythium ultimum nalidixic acid and incubating them for 48 hr at 30 C. The antibioticTrow on seeds. resistant strains were similar to their parent cultures. Rhizobacteria have been the subject of several reports Antagonistic properties of selected bacteria. The cell wall(11,12,16). It was suggested that the antibiotics or siderophores degrading enzymes-Exo-l,3-/3-D-glucosidase (13-I,3-glucanase, produced by these bacteria displace deleterious microorganisms, EC 3.2.1.58); Exo-l,4-f3-D-glucosidase (Cellulase, EC 3.2.1.74); presumably minor pathogens (11, 12). In such a case, competition and f-N-acetyl-D-glucosaminidase (Chitinase, EC 3.2.1.30)-were with the native microflora should also be considered. The assayed for filtrates of bacteria grown on either laminarin (Sigma), objectives of the present work were to isolate potential antagonistic chitin (Sigma), or cell walls or mycelium of Pythium rhizobacteria, apply them against Pythium damping-off, and aphanidermatum (Edson) Fitzp. as a sole carbon source. All investigate their antagonistic mechanism. enzymatic tests and preparation of fungal cell walls or mycelium were carried out according to previous publications (4,5). MATERIALS AND METHODS For production of inhibitory substances, bacteria were grown for 40 hr in a potato-dextrose and nutrient broth (each 15 g/L) Isolation and characterization of bacteria. One hundred thirty medium (PDNB). Bacterial cells were separated from the medium bacteria were isolated from roots of bean, cotton, radish, by centrifugation at 3,000 g, then the supernatant was sieved cucumber, and melon plants grown in soils infested with Pythium through a 0.45-•tm pore size filter (Millipore Corp., Bedford, MA). spp. or in peat-vermiculite growth media (PVM). Isolations were The cellfree medium, diluted with a fresh, double concentration of made on nutrient agar (NA) (Becton-Dickinson Corp., PDNB, was seeded with a mycelial disk taken from a 48-hr-old Cockeysville, MO) or King's medium B (KB) (10). Bacteria were culture of P. aphanidermatum. After 48 hr of incubation at 28 C, identified by the Analytical Profile Index (API) system (La Balme the mycelium was dried for 4 days at 60 C and weighed. Presence of antibiotics was also tested in solid NA. The publication costs of this article were defrayed in part by page charge payment. This Mats of mycelium removed from cultures of P. aphanidermatum article must therefore be hereby marked \"advertisement\" in accordance with 18 U.S.C. § 1734 solely to indicate this fact. grown for 48 hr in petri plates containing liquid PDNB were transferred into a fresh medium to check their growth in the ©1987 The American Phytopathological Society presence of bacteria. Dry weight gained by the fungus during the

250 citations

Journal ArticleDOI
TL;DR: In this paper, the authors evaluated the potential of actinoplanes campanulatus, Micromonospora chalcea and Streptomyces spiralis endophytic in cucumber roots, to promote plant growth and to protect seedlings and mature plants of cucumber from diseases caused by Pythium aphanidermatum, under greenhouse conditions.
Abstract: Aims: To evaluate the potential of Actinoplanes campanulatus, Micromonospora chalcea and Streptomyces spiralis endophytic in cucumber roots, to promote plant growth and to protect seedlings and mature plants of cucumber from diseases caused by Pythium aphanidermatum, under greenhouse conditions. Methods and Results: Three endophytic isolates, out of 29, were selected through tests aimed at understanding their mechanisms of action as biocontrol agents and plant growth promoters. When applied individually or in combination, they significantly promoted plant growth and reduced damping-off and crown and root rot of cucumber. The combination of the three isolates resulted in significantly better suppression of diseases and plant growth promotion, than where the plants were exposed to individual strains. Conclusions: The three selected actinomycete isolates colonized cucumber roots endophytically for 8 weeks, promoted plant growth and suppressed pathogenic activities of P. aphanidermatum on seedling and mature cucumber plants. Significance and Impact of the Study: The results clearly show that the endophytic, glucanase-producing actinomycetes used, especially as a combined treatment, could replace metalaxyl, which is the currently recommended fungicide for Pythium diseases in the United Arab Emirates. These endophytic isolates also have the potential to perform as plant growth promoters, which is a useful attribute for crop production in nutrient impoverished soils.

207 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202319
202241
202121
202025
201930
201828