Secondary Metabolite- and Endochitinase-Dependent Antagonism toward Plant-Pathogenic Microfungi of Pseudomonas fluorescens Isolates from Sugar Beet Rhizosphere

1998 ◽  
Vol 64 (10) ◽  
pp. 3563-3569 ◽  
Author(s):  
Mette Neiendam Nielsen ◽  
Jan Sørensen ◽  
Johannes Fels ◽  
Hans Christian Pedersen
Keyword(s):  
Biological Control ◽  
Cell Wall ◽  
Sugar Beet ◽  
Pseudomonas Fluorescens ◽  
Secondary Metabolite ◽  
Pythium Ultimum ◽  
Medium Composition ◽  
Fungal Antagonism ◽  
Lipopeptide Antibiotic

ABSTRACT Forty-seven isolates representing all biovars of Pseudomonas fluorescens (biovars I to VI) were collected from the rhizosphere of field-grown sugar beet plants to select candidate strains for biological control of preemergence damping-off disease. The isolates were tested for in vitro antagonism toward the plant-pathogenic microfungi Pythium ultimum and Rhizoctonia solani in three different plate test media. Mechanisms of fungal inhibition were elucidated by tracing secondary-metabolite production and cell wall-degrading enzyme activity in the same media. Most biovars expressed a specific mechanism of antagonism, as represented by a unique antibiotic or enzyme production in the media. A lipopeptide antibiotic, viscosinamide, was produced independently of medium composition by P. fluorescens bv. I, whereas the antibiotic 2,4-diacetylphloroglucinol was observed only in glucose-rich medium and only in P. fluorescens bv. II/IV. Both pathogens were inhibited by the two antibiotics. Finally, in low-glucose medium, a cell wall-degrading endochitinase activity in P. fluorescens bv. I, III, and VI was the apparent mechanism of antagonism toward R. solani. The viscosinamide-producing DR54 isolate (bv. I) was shown to be an effective candidate for biological control, as tested in a pot experiment with sugar beet seedlings infested with Pythium ultimum. The assignment of different patterns of fungal antagonism to the biovars of P. fluorescens is discussed in relation to an improved selection protocol for candidate strains to be used in biological control.

Biological control of damping-off of sugar-beet and cotton with Chaetomium globosum or a fluorescent Pseudomonas sp.

1988 ◽  
Vol 34 (5) ◽  
pp. 631-637 ◽  
Author(s):  
D. Walther ◽  
D. Gindrat
Keyword(s):  
Biological Control ◽  
Sugar Beet ◽  
Seed Treatment ◽  
Pythium Ultimum ◽  
Chaetomium Globosum ◽  
Pseudomonas Sp ◽  
Damping Off ◽  
Antifungal Metabolites ◽  
Fluorescent Pseudomonas

Seed treatment with ascospores of Chaetomium globosum reduced damping-off of sugar-beet caused by seed-borne Phoma betae and soil-borne Pythium ultimum or Rhizoctonia solani in growth chamber experiments. Seed treatment with a fluorescent Pseudomonas sp. controlled Ph. betae and P. ultimum but not R. solani. Coating cotton seeds with ascospores controlled P. ultimum and R. solani damping-off. In some experiments, biological seed treatments were equally or more effective than seed treatment with captan. However, greater variability in disease control occurred with the antagonists than with captan. Fifty percent of freshly harvested ascospores of C. globosum germinated in 8 h on water agar. When ascospores were stored under air-dried conditions for 3 days to 2.5 years, germination increased to > 90%. Under same storage conditions, survival of Pseudomonas sp. was detected after 4 months. Antagonistic activities observed in vitro were hyphal coiling of C. globosum on R. solani, and mycostasis was induced by C. globosum or Pseudomonas sp. on agar and soil. The presumed cause of mycostasis is the diffusible antifungal metabolites which may also be involved in the biological control of damping-off.

scholarly journals OPTIMALISASI PRODUKSI ENZIM KITINASE PADA ISOLAT JAMUR KITINOLITIK DARI SAMPEL TANAH RIZOSFER

2018 ◽  
Vol 3 (01) ◽  
pp. 62-69
Author(s):  
Eka Corneliyawati ◽  
Massora Massora ◽  
Khikmah Khikmah ◽  
As’ad Syamsul Arifin
Keyword(s):  
Biological Control ◽  
Cell Wall ◽  
Rhizosphere Soil ◽  
Plant Root ◽  
Optimal Growth ◽  
Chitinase Activity ◽  
Fungal Species ◽  
Plant Roots ◽  
Chitinase Production

The rhizosphere is the zone of soil surrounding a plant root where plant roots, soil and the soil biota interact with each other. Chitinolytic fungi has been effectively used in biological control agens. The chitinase activity causes lysis of the fungi cell wall pathogen. The aim of the research was to find optimization of activity chitinase enzyme from rhizosphere soil was conducted in vitro. Optimal growth chitinase production for TKR3 fungi isolate were concentration of chitin 0,2% (b/v), pH 5,5, temperature 30ºC, agitation 150 rpm and incubation time at four days. The optimum yield of chitinase production is influenced by fungal species and environmental conditions.

scholarly journals Variability in Sensitivity to Metalaxyl in vitro, Pathogenicity, and Control of Pythium spp. on Sugar Beet

Plant Disease ◽  
1998 ◽  
Vol 82 (8) ◽  
pp. 896-899 ◽  
Author(s):  
J. R. Brantner ◽  
Carol E. Windels
Keyword(s):  
Sugar Beet ◽  
Disease Control ◽  
Seed Treatment ◽  
Linear Growth ◽  
Pythium Ultimum ◽  
Infested Soil ◽  
Pathogenicity Tests ◽  
And Control ◽  
Treatment Sensitivity

Pythium ultimum var. sporangiiferum (76 isolates) and P. aphanidermatum (21 isolates) cultured from diseased sugar beet seedlings in Minnesota and North Dakota were tested for sensitivity to metalaxyl, pathogenicity on sugar beet, and disease control by metalaxyl seed treatment. Sensitivity to metalaxyl (effective concentration causing 50% growth inhibition [EC50]) was determined by linear growth on corn meal agar amended with 0, 0.01, 0.1, 1, 10, and 100 μg a.i. metalaxyl ml-1 after 48 h in the dark at 21 ± 1°C. Variation among isolates was significant (P = 0.05) within and between species, and EC50 values averaged 0.16 (range: 0.05 to 1.30 μg ml-1) for P. ultimum var. sporangiiferum and 2.06 (range: 1.19 to 3.12 μg ml-1) for P. aphanidermatum. In pathogenicity tests on sugar beet, most isolates of P. ultimum var. sporangiiferum (72 of 76) and all of P. aphanidermatum significantly (P = 0.05) decreased final stands compared to the noninoculated control. There was no correlation between aggressiveness in the absence of metalaxyl and in vitro sensitivity to metalaxyl. When Pythium-infested soil was planted with seed treated with metalaxyl at the standard (0.625 g a.i. kg-1) or half rate, some isolates that were least sensitive to metalaxyl in vitro resulted in a significant (P = 0.05) reduction in disease control. These results may explain, at least in part, why producers do not attain expected stands when they plant metalaxyl-treated sugar beet seed.

Parasitism of oospores of Pythium spp. by strains of Actinoplanes spp.

1993 ◽  
Vol 39 (10) ◽  
pp. 964-972 ◽  
Author(s):  
N. I. Khan ◽  
A. B. Filonow ◽  
L. L. Singleton ◽  
M. E. Payton
Keyword(s):  
Biological Control ◽  
Host Specificity ◽  
Pythium Ultimum ◽  
Pythium Myriotylum ◽  
Pythium Irregulare ◽  
Pythium Arrhenomanes ◽  
Parasite Specificity ◽  
Host Parasite ◽  
First Time

Strains of Actinoplanes spp. were evaluated for their in vitro parasitism of oospores of Pythium aphanidermatum, Pythium arrhenomanes, Pythium irregulare, Pythium myriotylum, and Pythium ultimum. Oospores of Pythium arrhenomanes, Pythium irregulare, and Pythium myriotylum were identified for the first time as hosts of Actinoplanes spp. Newly recorded parasites of oospores of Pythium spp. were Actinoplanes azureus, Actinoplanes brasiliensis, Actinoplanes caeruleus, Actinoplanes ferrugineus, Actinoplanes ianthinogenes, Actinoplanes italicus, Actinoplanes minutisporangius, Actinoplanes rectilineatus, Actinoplanes teichomyceticus, Actinoplanes utahensis, Actinoplanes violaceous, Actinoplanes yunnahenis, plus 15 strains of Actinoplanes yet to be speciated. Parasitized oospores had disorganized cytoplasms and hyphae of Actinoplanes sp. emerging from them. Infection of oospores in vitro varied from 0 to > 90%. Strains also were very active parasites of oospores in sterile soils. When added to nonsterile soils, several strains increased (p = 0.05) the level of oospore parasitism compared with nonsupplemented soils. Strains of Actinoplanes spp. exhibited a host specificity for species of Pythium in vitro and in soil. Sporulation of Actinoplanes sp. from infected oospores incubated on soil was frequent and more abundant than that observed in vitro.Key words: Pythium spp., Actinoplanes spp., actinomycetes, biological control, host–parasite specificity.

scholarly journals Viscosinamide-producing Pseudomonas fluorescens DR54 exerts a biocontrol effect on Pythium ultimum in sugar beet rhizosphere

2000 ◽  
Vol 33 (2) ◽  
pp. 139-146 ◽  
Author(s):  
Charlotte Thrane ◽  
Tommy Harder Nielsen ◽  
Mette Neiendam Nielsen ◽  
Jan Sørensen ◽  
Stefan Olsson
Keyword(s):  
Sugar Beet ◽  
Pseudomonas Fluorescens ◽  
Pythium Ultimum

scholarly journals Isolation and Antifungal and Antioomycete Activities of Aerugine Produced by Pseudomonas fluorescens Strain MM-B16

2003 ◽  
Vol 69 (4) ◽  
pp. 2023-2031 ◽  
Author(s):  
Jung Yeop Lee ◽  
Surk Sik Moon ◽  
Byung Kook Hwang
Keyword(s):  
Pseudomonas Fluorescens ◽  
Spectral Data ◽  
Bacterial Strain ◽  
Plant Pathogens ◽  
Phytophthora Capsici ◽  
Pythium Ultimum ◽  
Mountain Forest ◽  
Molecular Formula

ABSTRACT The bacterial strain MM-B16, which showed strong antifungal and antioomycete activity against some plant pathogens, was isolated from a mountain forest soil in Korea. Based on the physiological and biochemical characteristics and 16S ribosomal DNA sequence analysis, the bacterial strain MM-B16 was identical to Pseudomonas fluorescens. An antibiotic active against Colletotrichum orbiculare and Phytophthora capsici in vitro and in vivo was isolated from the culture filtrates of P. fluorescens strain MM-B16 using various chromatographic procedures. The molecular formula of the antibiotic was deduced to be C10H11NO2S (M+, m/z 209.0513) by analysis of electron impact mass spectral data. Based on the nuclear magnetic resonance and infrared spectral data, the antibiotic was confirmed to have the structure of a thiazoline derivative, aerugine [4-hydroxymethyl-2-(2-hydroxyphenyl)-2-thiazoline]. C. orbiculare, P. capsici, and Pythium ultimum were most sensitive to aerugine (MICs for these organisms were approximately 10 μg ml−1). However, no antimicrobial activity was found against yeasts and bacteria even at concentrations of more than 100 μg ml−1. Treatment with aerugine exhibited a significantly high protective activity against development of phytophthora disease on pepper and anthracnose on cucumber. However, the control efficacy of aerugine against the diseases was in general somewhat less than that of the commercial fungicides metalaxyl and chlorothalonil. This is the first study to isolate aerugine from P. fluorescens and demonstrate its in vitro and in vivo antifungal and antioomycete activities against C. orbiculare and P. capsici.

An endophytic chitinase-producing isolate of Actinoplanes missouriensis, with potential for biological control of root rot of lupin caused by Plectosporium tabacinum

2003 ◽  
Vol 51 (3) ◽  
pp. 257 ◽  
Author(s):  
Khaled A. El-Tarabily
Keyword(s):  
Biological Control ◽  
Cell Wall ◽  
Root Rot ◽  
Germ Tube ◽  
First Record ◽  
Plant Roots ◽  
Wild Type ◽  
Type Isolate ◽  
Cell Wall Lysis

Twenty-one streptomycete and 15 non-streptomycete actinomycetes were isolated from surface-disinfested lupin roots and evaluated for their potential to produce chitinase and to inhibit the growth of Plectosporium tabacinum, the causal agent of lupin root rot in Egypt. The most inhibitory isolate was identified as Actinoplanes missouriensis which produced relatively high levels of chitinase and degraded the hyphae of P.�tabacinum in vitro, causing extensive plasmolysis and cell-wall lysis. A crude culture filtrate of A. missouriensis exhibited antifungal activity and significantly (P < 0.05) reduced spore germination and germ-tube growth of the pathogen. The antagonist was recovered from inside the root at all samplings up to 8 weeks after inoculation, indicating that the roots of healthy lupin may be a habitat for the endophyte. A. missouriensis significantly (P < 0.05) reduced the severity of root rot under glasshouse conditions. An endophytic isolate of Actinoplanes italicus incapable of producing chitinase and a mutant strain of A. missouriensis that did not produce detectable levels of chitinase, did not lyse hyphae of P. tabacinum or reduce root rot in the glasshouse experiments, although colonisation of the lupin root by both these isolates was similar to that of the chitinase-producing wild-type isolate of A. missouriensis. This study is the first record of control of a soil-borne plant pathogen by a chitinolytic actinomycete, endophytic in plant roots.

scholarly journals Biological control of cucumber and sugar beet damping-off caused by Pythium ultimum with bacterial and fungal antagonists

2002 ◽  
Vol 92 (6) ◽  
pp. 1078-1086 ◽  
Author(s):  
D.G. Georgakopoulos ◽  
P. Fiddaman ◽  
C. Leifert ◽  
N.E. Malathrakis
Keyword(s):  
Biological Control ◽  
Sugar Beet ◽  
Pythium Ultimum ◽  
Damping Off

scholarly journals Chromosomal Insertion of Phenazine-1-Carboxylic Acid Biosynthetic Pathway Enhances Efficacy of Damping-off Disease Control by Pseudomonas fluorescens

2000 ◽  
Vol 13 (12) ◽  
pp. 1293-1300 ◽  
Author(s):  
T. M. Timms-Wilson ◽  
R. J. Ellis ◽  
A. Renwick ◽  
D. J. Rhodes ◽  
D. V. Mavrodi ◽  
...  
Keyword(s):  
Carboxylic Acid ◽  
Pseudomonas Fluorescens ◽  
Plant Protection ◽  
Pythium Ultimum ◽  
Single Copy ◽  
Antifungal Compound ◽  
Damping Off ◽  
Ecological Fitness ◽  
Plant Growth Promoting

A disarmed Tn5 vector (pUT∷Ptac-phzABCDEFG) was used to introduce a single copy of the genes responsible for phenazine-1-carboxylic acid (PCA) biosynthesis into the chromosome of a plant-growth-promoting rhizobacterium Pseudomonas fluorescens. The PCA gene cluster was modified for expression under a constitutive Ptac promoter and lacked the phzIR regulators. PCA-producing variants significantly improved the ability of the wild-type P. fluorescens to reduce damping-off disease of pea seedlings caused by Pythium ultimum, even under conditions of heavy soil infestation. Under conditions of oxygen limitation that are typical of the rhizosphere, PCA production per cell in vitro was greater than that recorded in fast-growing, nutrient-rich cultures. Similarly, when the in vitro nutrient supply was limited, P. fluorescens∷phz variants that produced the most PCA effectively competed against P. ultimum by suppressing mycelial development. Soil-based bioassays confirmed that the level of PCA biosynthesis correlated directly with the efficacy of biological control and the persistence of inocula in soil microcosms. They also showed that soil pretreatment with bacteria provides a suitable method for plant protection by reducing infection, effectively decontaminating the soil. These data demonstrate that the insertion of a single chromosomal copy of the genes for a novel antifungal compound, PCA, enhances the ecological fitness of a natural isolate already adapted to the rhizosphere and capable of suppressing fungal disease.

scholarly journals Comparison of Muscodor albus Volatiles with a Biorational Mixture for Control of Seedling Diseases of Sugar Beet and Root-Knot Nematode on Tomato

Plant Disease ◽  
2007 ◽  
Vol 91 (2) ◽  
pp. 220-225 ◽  
Author(s):  
E. Grimme ◽  
N. K. Zidack ◽  
R. A. Sikora ◽  
G. A. Strobel ◽  
B. J. Jacobsen
Keyword(s):  
Sugar Beet ◽  
Meloidogyne Incognita ◽  
Pythium Ultimum ◽  
In Vivo Studies ◽  
Damping Off ◽  
Root Knot Nematode ◽  
Seedling Diseases ◽  
Muscodor Albus

A biorational synthetic mixture of organic components mimicking key antimicrobial gases produced by Muscodor albus was equivalent to the use of live M. albus for control of seedling diseases of sugar beet (Beta vulgaris) caused by Pythium ultimum, Rhizoctonia solani AG 2-2, and Aphanomyces cochlioides. The biorational mixture provided better control than the live M. albus formulation for control of root-knot nematode, Meloidogyne incognita, on tomato (Lycopersicon esculentum). The biorational mixture provided control of damping-off equal to a starch-based formulation of the live fungus for all three sugar beet pathogens, and significantly reduced the number of root-knot galls on tomato roots compared with a barley-based formulation. Rate studies with the biorational mixture showed that 2 and 0.75 µl/cm3 of soil were required to provide optimal control of Rhizoctonia and Pythium damping-off of sugar beet, respectively. Five microliters of biorational mixture per milliliter of water was required for 100% mortality in 24 h for Meloidogyne incognita in in vitro studies. In in vivo studies, 1.67 µl of the biorational mixture/cm3 of sand resulted in fewer root-knot galls than a Muscodor albus infested ground barley formulation applied at 5 g/liter of sand.

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