Survival and inoculum potential of conidia and chlamydospores of Fusarium oxysporum f.sp. lini in soil

1990 ◽  
Vol 36 (8) ◽  
pp. 551-556 ◽  
Author(s):  
Yvonne Couteaudier ◽  
C. Alabouvette
Keyword(s):  
Enzymatic Activity ◽  
Fusarium Oxysporum ◽  
Key Words ◽  
Inoculum Density ◽  
Fluorescein Diacetate ◽  
Natural Soil ◽  
Inoculum Potential ◽  
Kinetics Of ◽  
Grown Culture

The kinetics of survival and inoculum potential of Fusarium oxysporum f. sp. lini were studied in soil. Two types of inoculum were compared: microconidia freshly harvested from a laboratory-grown culture and microchlamydospores produced in sterilized soil. Introduced at the same inoculum densities into a natural soil, the two types of inoculum showed similar behaviour; the inoculum densities changed little with time, at least during 100 days. However, the two types of inoculum did differ in disease potential. A higher percentage of microchlamydospores than microconidia germinated in the rhizosphere of flax seedlings, and the heterotrophic fluorescein diacetate hydrolysing activity of the microchlamydospores was 100 times higher than that of microconidia. Moreover, the microchlamydospores produced more disease on flax than the microconidia even at a much lower inoculum density. Key words: survival, inoculum potential, enzymatic activity, conidia, chlamydospores, Fusarium oxysporum, soil.

scholarly journals Fusarium Consortium Populations Associated with Asparagus Crop in Spain and Their Role on Field Decline Syndrome

2020 ◽  
Vol 6 (4) ◽  
pp. 336
Author(s):  
Alexandri María Brizuela ◽  
Eduardo De la Lastra ◽  
José Ignacio Marín-Guirao ◽  
Laura Gálvez ◽  
Miguel de Cara-García ◽  
...  
Keyword(s):  
Fusarium Oxysporum ◽  
Fusarium Species ◽  
Management Strategies ◽  
Statistical Correlation ◽  
Inoculum Density ◽  
Average Temperature ◽  
Species Complexes ◽  
Main Production ◽  
Production Areas ◽  
Prevalent Species

Asparagus Decline Syndrome (ADS) is one of the main phytosanitary problems of asparagus crop worldwide. Diseased plants and soil samples from 41 fields from three main production areas of Spain were surveyed. Eight Fusarium species belonging to seven species complexes were identified in soils: F. oxysporum, F. proliferatum, F. redolens, F. solanisensu stricto, F. equiseti, F. culmorum, F. compactum and F. acuminatum. Fusarium oxysporum was the most prevalent species. Statistical correlation (R2 = 88%) was established between F. oxysporum inoculum density and the average temperature of the warmest month. A relationship was also established between three crop factors (average temperature, crop age and F. oxysporum inoculum density) and field disease indices. Significant differences were observed between the distribution of F. oxysporum propagules in white and green asparagus fields. Thirteen Fusarium species belonging to seven species complexes were identified from roots of diseased plants, being F. oxysporum the most prevalent. F. proliferatum, F. oxysporum and F. redolens showed pathogenicity to asparagus and were the main species associated to ADS. Fusarium oxysporum was the species with the highest genetic diversity displaying 14 sequence-based haplotypes with no geographic differentiation. This work contributes to understanding the Fusarium complex associated to ADS for developing accurate integrated disease management strategies.

The influence of Fusarium oxysporum f. sp. medicaginis on total soluble-sugar concentration of infected alfalfa roots

1993 ◽  
Vol 73 (2) ◽  
pp. 647-649 ◽  
Author(s):  
C. Richard ◽  
J.-G. Martin
Keyword(s):  
Fusarium Oxysporum ◽  
Key Words ◽  
Freezing Tolerance ◽  
Soluble Sugar ◽  
Soluble Sugars ◽  
Frost Tolerance ◽  
Root Tissue ◽  
Sugar Concentration ◽  
Low Concentration ◽  
Total Soluble Sugar

Alfalfa was inoculated with Fusarium oxysporum f. sp. medicaginis, and the total soluble-sugar concentration was determined in diseased taproots of cold-hardened plants. The concentration of soluble sugars decreased with increasing discoloration of root tissue (r = −0.85, P ≤ 0.0001). The low concentration of soluble sugars might be responsible for the previously reported low freezing tolerance of Fusarium-infected alfalfa. Key words: Alfalfa, Fusarium, sugars, frost tolerance

DNA-based quantification of Fusarium oxysporum f. sp. vasinfectum in environmental soils to describe spatial variation in inoculum density

Plant Disease ◽  
2022 ◽  
Author(s):  
Roy Davis ◽  
Thomas Isakeit ◽  
Thomas Chappell
Keyword(s):  
United States ◽  
Fusarium Oxysporum ◽  
Spatial Scales ◽  
The United States ◽  
Inoculum Density ◽  
Root Knot Nematode ◽  
West Texas ◽  
Sudden Appearance ◽  
Digital Polymerase Chain Reaction ◽  
Race 4

Fusarium wilt of cotton, caused by the soilborne fungal pathogen Fusarium oxysporum f. sp. vasinfectum (FOV), occurs in regions of the United States where cotton (Gossypium spp.) is grown. Race 4 of this pathogen (FOV4) is especially aggressive and does not require the co-occurrence of the root knot nematode (Meloidogyne incognita) to infect cotton. Its sudden appearance in far-west Texas in 2016 after many years of being restricted to California is of great concern, as is the threat of its continued spread through the cotton-producing regions of the United States. The aim of this research was to analyze the spatial variability of FOV4 inoculum density in the location where FOV4 is locally emerging, using quantitative and droplet digital polymerase chain reaction (qPCR and ddPCR) methods. Soil samples collected from a field with known FOV4 incidence in Fabens, Texas were analyzed. Appreciable variation in inoculum density was found to occur at spatial scales smaller than the size of plots involved in cultivar trial research, and was spatially autocorrelated (Moran’s I, Z = 17.73, p < 0.0001). These findings indicate that for cultivar trials, accounting for the spatial distribution of inoculum either by directly quantifying it or through the use of densely-distributed “calibration checks” is important to the interpretation of results.

The Influence of 5-Aminolevulinic Acid on Protochlorophyllide and Protochlorophyll Accumulation in Dark-Grown Scenedesmus

1990 ◽  
Vol 45 (1-2) ◽  
pp. 71-73 ◽  
Author(s):  
Kiriakos Kotzabasis ◽  
Horst Senger
Keyword(s):  
Aminolevulinic Acid ◽  
Protein Complexes ◽  
Chlorophyll Biosynthesis ◽  
Scenedesmus Obliquus ◽  
Good Tool ◽  
Future Studies ◽  
Pigment Protein Complexes ◽  
Kinetics Of ◽  
Grown Culture ◽  
In Cells

The intermediate of chlorophyll biosynthesis, 5-aminolevulinic acid (ALA ), is a necessary prerequisite for the formation of protochlorophyllide (PChlide) and protochlorophyll (PChl) in the dark. The application of ALA to a dark-grown culture of the pigment mutant C-2 A′ of Scenedesmus obliquus increased the amount of PChlide 30-fold and the amount of PChl about 10-fold. The rates of ALA-dependent formation of PChlide and PChl reach their maximum values at different concentrations of added ALA . Similarly, the kinetics of PChlide and PChl formation in cells incubated with ALA are different. Cells of Scenedesmus mutant C-2 A′ incubated with various concentrations of ALA for different periods provide a good tool for future studies differentiating between PChlide and PChl metabolism . − The incorporation of Chl deriving from either PChl or PChlide into different pigment protein complexes is discussed.

Production of amylases by yeasts

1990 ◽  
Vol 36 (11) ◽  
pp. 751-753 ◽  
Author(s):  
Valter R. Linardi ◽  
Katia M. G. Machado
Keyword(s):  
Enzymatic Activity ◽  
Key Words ◽  
Wheat Bran ◽  
Aureobasidium Pullulans ◽  
Natural Habitats ◽  
Semisolid Medium ◽  
Debranching Enzyme ◽  
Candida Kefyr ◽  
Candida Famata ◽  
High Enzymatic Activity

Yeasts (228) isolated for natural habitats were screened for their ability to produce amylases in semisolid medium of wheat bran. Strains of Aureobasidium pullulans, Candida famata, and Candida kefyr showed high enzymatic activity for α-amylase, glucoamylase, and debranching enzyme. Key words: Aureobasidium, Candida, amylolytic yeasts, α-amylase, glucoamylase.

Root-rot resistance in common bean

1993 ◽  
Vol 73 (1) ◽  
pp. 365-367 ◽  
Author(s):  
J. C. Tu ◽  
S. J. Park
Keyword(s):  
Phaseolus Vulgaris ◽  
Rhizoctonia Solani ◽  
Common Bean ◽  
Fusarium Oxysporum ◽  
Key Words ◽  
Fusarium Solani ◽  
Root Rot ◽  
Pythium Ultimum ◽  
Growth Room

A bean (Phaseolus vulgaris) line, A - 300, resistant to Rhizoctonia solani and Fusarium oxysporum was introduced into Ontario from Colombia. The results of tests conducted in a root-rot nursery, in a greenhouse and in a growth room showed that this bean line is resistant to Fusarium solani f. sp. phaseoli and Pythium ultimum. Key words: Bean, Phaseolus vulgaris, root rot resistance

Vegetative compatibility groupings in a local population of Fusarium oxysporum

1991 ◽  
Vol 69 (1) ◽  
pp. 168-172 ◽  
Author(s):  
T. R. Gordon ◽  
D. Okamoto
Keyword(s):  
Fusarium Oxysporum ◽  
Key Words ◽  
Local Population ◽  
San Joaquin Valley ◽  
Vegetative Compatibility ◽  
Vegetative Compatibility Groups ◽  
Heterokaryon Formation ◽  
Pathogenicity Tests

One hundred isolates of Fusarium oxysporum collected from soil in the San Joaquin Valley in 1988 were tested for their ability to form intra- and inter-isolate heterokaryons. Five thousand and fifty isolate combinations were tested for vegetative compatibility, using complementary nitrate nonutilizing mutants. Ninety-eight combinations (2%) produced weakly positive reactions, 248 (5%) produced strong reactions, and 4704 combinations (93%) were negative for heterokaryon formation. This result suggests that anastomosis occurs infrequently among isolates in this population. Isolates were assigned to vegetative compatibility groups based on strong reactions. By this procedure 100 isolates were placed in 29 vegetative compatibility groups. At least one isolate from each of the 29 vegetative compatibility groups was tested and found to be vegetatively incompatible with the muskmelon wilt pathogen, F. oxysporum f. sp. melonis, which occurs in the same field. Each of these isolates also was avirulent to muskmelon in greenhouse pathogenicity tests. Forty isolates of F. oxysporum were collected in 1989 and 32 (80%) were compatible with isolates collected in 1988. The remaining eight isolates represented eight different vegetative compatibility groups. Key words: anastomosis, fungi, heterokaryon.

Comparison of the nucleophilicities of alcohols and alkoxides

2005 ◽  
Vol 83 (9) ◽  
pp. 1554-1560 ◽  
Author(s):  
Thanh Binh Phan ◽  
Herbert Mayr
Keyword(s):  
Free Energy ◽  
Key Words ◽  
Rate Constants ◽  
Correlation Equation ◽  
Linear Free Energy Relationship ◽  
Hydroxide Solution ◽  
Linear Free Energy ◽  
S Parameters ◽  
Nucleophilic Reactivity ◽  
Kinetics Of

The kinetics of the reactions of benzhydrylium ions with some alcohols and alkoxides dissolved in the corresponding alcohols were photometrically investigated. Using the correlation equation log k (20 °C) = s(E + N), the N and s parameters of methoxide, ethoxide, n-propoxide, and isopropoxide in alcohol–acetonitrile (91:9, v/v) were determined. The cosolvent acetonitrile has only a little influence on the rate constants of the reactions of alcohols and alkoxides. The order of N values (OH– << MeO– < EtO– < n-PrO– < i-PrO–) shows that alkoxides differ only moderately in reactivity but are considerably more nucleophilic than hydroxide. As a consequence, the nucleophilic reactivity of a 0.5 mmol/L aqueous hydroxide solution increases by a factor of 13 when 10% (v/v) methanol is added. In 1–10 mmol/L alkoxide solutions in alcohols, weak electrophiles react considerably faster with alkoxides than with the corresponding alcohols. With increasing electrophilicity, the preference for alkoxides decreases, and electrophiles of –3 < E < 3 react with alkoxides (1–10 mmol/L) and alcohols with comparable rates. Stronger electrophiles will react with alcohols exclusively when alkoxides are present in concentrations ≤10 mmol/L. Key words: kinetics, alcohol, alkoxide, linear free energy relationship, nucleophilicity.<

Kinetic and equilibrium studies of the acid dissociation of the cobalt(II) complexes of N,N'-dialkyl- 1,10-phenanthroline-2,9-dimathanamine ligands

1999 ◽  
Vol 77 (9) ◽  
pp. 1471-1475 ◽  
Author(s):  
Hongwei Sun ◽  
Zhifen Zhou ◽  
Huakuan Lin ◽  
Guanghua Zhao ◽  
Shourong Zhu ◽  
...  
Keyword(s):  
Linear Relationship ◽  
Key Words ◽  
Dissociation Rate ◽  
Acid Dissociation ◽  
Stopped Flow ◽  
Isokinetic Temperature ◽  
Dissociation Kinetics ◽  
Equilibrium Studies ◽  
Complexation Property ◽  
Kinetics Of

The complexation property and the acid dissociation kinetics of four N,N'-dialkyl-1,10-phenanthroline-2,9-dimathanamine complexes with cobalt(II) were studied using a pH meter and a stopped-flow spectrophotometer. In 6.6 × 10-3~0.5 mol dm-3 HCl (I = 0.5 mol dm-3 HCl + NaCl), the dissociation rate follows the law kobs = kK2[H+]/(1 + K2[H+]). The acid dissociation can be rationalized in terms of a four-step kinetic process involving two rapid pre-equilibrium protonations and rate-determining cleavage of the Co(II)-N(phenanthroline) bond. The temperature dependence of the rate was determined, and the appropriate thermodynamic parameters were obtained. The linear relationship between ΔH not equal and ΔS not equal suggests that an isokinetic temperature, Tiso of 282 ± 2 K exists. Key words: N,N'-dialkyl-1,10-phenanthroline-2,9-dimathanamine, complexation property, acid dissociation kinetics, mechanism, cobalt(II) complex.

Induction and Repression Kinetics of Fungal Beta-Fructofuranosidase in Submerged Culture

2009 ◽  
Vol 5 (2) ◽  
Author(s):  
Armando Robledo-Olivo ◽  
Juan C Contreras-Esquivel ◽  
Raul Rodriguez Herrera ◽  
Cristobal N Aguilar
Keyword(s):  
Aspergillus Niger ◽  
Enzymatic Activity ◽  
Biomass Production ◽  
Submerged Culture ◽  
Enzyme Production ◽  
Maximum Rate ◽  
Sucrose Concentration ◽  
Viable Option ◽  
Initial Concentration ◽  
Kinetics Of

Invertase production by Aspergillus niger in submerged culture was evaluated under different concentrations of sucrose and glucose. When the initial concentration of sucrose was increased from 6.25 to 50 gL-1, a higher biomass production (6.1 gL-1) was observed. The biomass production was increased 4 times more when a glucose-sucrose combination was used as substrate (26.31 gL-1). The strain A. niger produced extracellular beta-fructofuranosidase activity at all test concentrations of the substrate and the highest enzymatic activity (3873 UL-1) was obtained when sucrose was used at 12.5 gL-1. However, with a glucose-sucrose concentration of 25 gL-1 the beta-fructofuranosidase activity was of 23706 UL-1. The maximum rate of invertase enzyme production in presence of sucrose by Aspergillus niger in submerged culture was 3.67 UL-1h-1 at 12.5 gL-1 concentration, while in the case of glucose-sucrose mixture, it was 13.95 UL-1h-1 at a concentration of 25 gL-1. It was observed that the enzyme yield (YE/X) was 1.25 times more in presence of sucrose than with glucose-sucrose combination. In addition, the results suggested that an addition of lower concentration of glucose is a viable option to increase the enzyme secretion by the fungi.

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