Further observations on the growth of flax rust fungus in axenic culture

1984 ◽  
Vol 62 (10) ◽  
pp. 2175-2180 ◽  
Author(s):  
Rosalinda Boasson ◽  
Michael Shaw
Keyword(s):  
Heat Shock ◽  
Incubation Period ◽  
Rust Fungus ◽  
Axenic Culture ◽  
Subsequent Development ◽  
Stages Of Growth ◽  
Melampsora Lini ◽  
Tube Emergence ◽  
Initial Ph ◽  
Total Growth

Axenic cultures of flax rust (Melampsora lini (Ehrenb.) Lév.) grown from sterile uredospores on a defined liquid medium in 125-mL Erlenmeyer flasks exhibited an incubation period of 12 to 20 days followed by a period of rapid growth and sporulation. A heat shock (31–33 °C for 2–2.5 h) administered 3 h after seeding the medium did not induce the formation of infection structures, but doubled the number of vegetative colonies initiated and increased total growth per flask (protein/flask) in 4 weeks by 20-fold. The optimum timing of the heat shock corresponded closely with the maximum rate of germ tube emergence. Ambient CO2 was not essential for germination or perception of the heat shock, but was essential, during the first half of the incubation period, for the subsequent development of vegetative colonies. CO2 fixation occurred at all stages of growth from 1 day onward, 14CO2 being incorporated into ethanol-insoluble and ethanol-soluble fractions, including amino acids. Growth rate following the incubation period was not affected by the initial pH of the medium between 5.0 and 6.0, but the incubation period was shorter at pH 6.0.

Effect of heat shock on protein synthesis in flax rust uredosporelings

1985 ◽  
Vol 63 (11) ◽  
pp. 2069-2076 ◽  
Author(s):  
Maichael Shaw ◽  
Rosalinda Boasson ◽  
Leroy Scrubb
Keyword(s):  
Heat Shock ◽  
Gel Electrophoresis ◽  
Polyacrylamide Gel Electrophoresis ◽  
Heat Stroke ◽  
Sodium Dodecyl ◽  
Axenic Culture ◽  
One Dimensional ◽  
Melampsora Lini ◽  
Molecular Masses ◽  
Shock Proteins

In uredosporelings of Melampsora lini (Ehrenb.) Lév. germinated for 3 h, uptake of [35S]methionine and its incorporation into protein were depressed during a 2-h heat shock induced by transfer from 17 ± 0.5 to 31 °C. Spectrophotometric scans of fluorograms, prepared after one-dimensional sodium dodecyl sulphate – polyacrylamide gel electrophoresis of aliquots of protein extracts containing equal numbers of disintegrations per minute (1 dps = 1 Bq) in protein, showed that heat shock induced statistically significant changes in the relative degrees of incorporation of [35S]methionine into 15 polypeptide bands. Increased labelling occurred in seven bands, which appear to be heat shock proteins with apparent molecular masses of 84, 71, 43.5, 30.5, 19.5, 18, and 17 kD. Decreased labelling occurred in eight bands, which appear to be heat stroke proteins with apparent molecular masses of 56, 54, 48, 46, 34, 32, 31.5, and 14 kD. When [35S]methionine was administered during heat shock at 31 °C the same pattern of polypeptide labelling was observed in extracts made immediately without return to 17 °C and in extracts made after uredosporelings were returned to 17 °C for 24 h. Thus label incorporated into each polypeptide during heat shock was retained for at least 24 h after the return to 17 °C. Administration of [35S]methionine at 17 °C after completion of the heat shock showed that the "normal" or "nonshock" pattern of labelling began to be resumed within 2 h after transfer from 31 to 17 °C. The results are discussed in relation to the effect of heat shock in promoting the initiation and growth of mycelial colonies from uredosporelings in axenic culture.

The effects of glutamine, citrate, and pH on the growth and sporulation of Melampsora lini in axenic culture

1988 ◽  
Vol 66 (6) ◽  
pp. 1230-1236 ◽  
Author(s):  
Rosalinda Boasson ◽  
Michael Shaw
Keyword(s):  
Incubation Period ◽  
Axenic Culture ◽  
Inhibitory Effect ◽  
Low Ph ◽  
Melampsora Lini

Growth (protein) and sporulation (extinction at 458 nm) of uredial cultures of races 3 and 210 of flax rust were compared on axenic media containing cysteine plus either high (42 mM) aspartate or glutamate or high (42 mM) or low (4 mM) glutamine as the major source of amino N. On high aspartate, growth of race 210 was 2 times and sporulation 20 times that of race 3. Glutamate substituted for aspartate, but there was no growth on high glutamine unless cultures were first seeded and held on glutamate during an incubation period of 15 days. Growth on low glutamine was poor at pH 5.0. Increased pH or the addition of citrate overcame the inhibitory effect of low pH. Both races grew equally well on low glutamine at pH 5.5 or 6.0, with or without citrate, but growth of race 3 was only one-third to one-half that of race 210 on high aspartate. Sporulation of race 210 on low glutamine under these conditions was 4–5 times that of race 3, being as high as or higher than on aspartate. [14C(U)]Citrate was more rapidly metabolized at pH 5.0 than at 5.5 or 6.0. Evidence is presented that citrate promotes growth on low glutamine at pH 5.0 primarily because it prevents the rapid downward drift in pH that occurs in its absence and that periodic upward adjustment of the pH results in striking increases in sporulation.

The transition from germ tubes to vegetative growth in uredospores of Melampsora lini

1991 ◽  
Vol 69 (8) ◽  
pp. 1715-1718 ◽  
Author(s):  
R. Boasson ◽  
M. Shaw
Keyword(s):  
Vegetative Growth ◽  
Mycelial Growth ◽  
Rust Fungus ◽  
Axenic Culture ◽  
Single Spore ◽  
Naked Eye ◽  
Melampsora Lini ◽  
Rate Of Increase ◽  
Germ Tubes ◽  
Spore Densities

The transition from uredospore germ tubes to vegetative hyphae marks the initiation of mycelial colonies of Melampsora lini growing in axenic culture. It is promoted by heat shock (31 °C for 2 h) and is arbitrarily defined as having occurred when mitotic divisions of the two original uredospore nuclei have produced more than four nuclei. The percentage of germinating spores in which it occurs (percentage initiation) does not increase beyond 48 h after seeding and is higher (about 9 vs. 5%) at a low (18 spores/mm2) than at a higher (90 spores/mm2) inoculum density. The number of nuclei in a mycelial colony arising from a single uredospore increases exponentially with a mean doubling time of 2.40 days. Neither the percentage initiation nor the rate of increase in number of nuclei (= mycelial growth) are affected by the proximity of neighbouring spores at spore densities of the order of 18 spores/mm2. Approximately 10% of the initiated colonies exhibit a growth rate that renders them visible to the naked eye after 5 weeks. Key words: rust fungus, axenic culture, vegetative growth, single spore colonies.

The effects of heat shock and inoculum density on growth and sporulation in axenic cultures of the flax rust fungus

1988 ◽  
Vol 66 (1) ◽  
pp. 189-193 ◽  
Author(s):  
Rosalinda Boasson ◽  
Michael Shaw
Keyword(s):  
Heat Shock ◽  
Liquid Medium ◽  
Rust Fungus ◽  
Primary Factor ◽  
Melampsora Lini ◽  
Colony Number ◽  
Axenic Cultures ◽  
Axenic Conditions ◽  
Logarithmic Growth ◽  
Respective Number

The number of mycelial colonies of Melampsora lini (Ehrenb.) Lév. was increased by a 2-h heat shock at 31 °C delivered 3 h after uredospores were seeded on a liquid medium at 17 ± 0.5 °C under axenic conditions. At 35–38 days from seeding, the ratio of the respective number of colonies in shock and nonshock treatments in 125-mL culture flasks was highest (7.5 to 22) at inoculum levels (1 to 4 × 103 uredospores cm−2) that yielded about 10 colonies per flask without heat shock; the ratio declined sharply at inoculum levels adjusted to yield either smaller or larger numbers of colonies per flask without heat shock. Sporulation (extinction at 458 nm) and protein per colony were positively correlated; were not directly affected by heat shock; were determined by colony number; increased to maxima as mean colony number per flask increased from 1 or less to from 10 to 100 in different experiments; and decreased at higher colony numbers per flask. The results indicate that heat shock promotes the initiation of colonies; that colony number determines the duration of logarithmic growth; and that increasing competition among individual colonies is the primary factor limiting growth and sporulation, whether or not the uredospore germlings are subjected to heat shock.

Colony initiation in flax rust in axenic culture: involvement of a volatile factor

1979 ◽  
Vol 57 (23) ◽  
pp. 2657-2662 ◽  
Author(s):  
Rosalinda Boasson ◽  
Michael Shaw
Keyword(s):  
Carbon Dioxide ◽  
Axenic Culture ◽  
Conclusive Evidence ◽  
Culture Flask ◽  
Melampsora Lini ◽  
Air Space ◽  
Lag Period ◽  
Axenic Cultures ◽  
Incubation Temperatures

In axenic cultures of flax rust (Melampsora lini) colonies are initiated after a lag period of 12–20 days, depending partly on incubation temperatures. Colony initiation is completely inhibited by removal of a volatile factor which is absorbed by KOH in the air space of the culture flask. The fungus remains sensitive to this inhibition for 8–10 days, i.e., until shortly before visible colonies would normally have developed. While in the presence of KOH, the fungus is not killed; cultures grow normally after removal of the KOH.Although conclusive evidence must await further work, the available data strongly suggest that carbon dioxide is responsible for this effect.

Improvement of delta-endotoxin production from local Bacillus thuringiensis Se13 using Taguchi’s orthogonal array methodology

2018 ◽  
Vol 43 (6) ◽  
pp. 662-670 ◽  
Author(s):  
Ardahan Eski ◽  
Zihni Demirbağ ◽  
İsmail Demir
Keyword(s):  
Bacillus Thuringiensis ◽  
Incubation Period ◽  
Orthogonal Array ◽  
Incubation Temperature ◽  
Taguchi Methods ◽  
Optimum Level ◽  
Optimum Conditions ◽  
Delta Endotoxin ◽  
Initial Ph ◽  
Four Levels

Abstract Objective The insecticidal activity of Bacillus thuringiensis directly depends on the yield of delta-endotoxins. In this study, various nutritional and cultural parameters influencing delta-endotoxin synthesis by a local isolate of B. thuringiensis Se13 were investigated using Taguchi methods. Methods In the first experiment, four factors, incubation period, incubation temperature, initial pH and medium, each at four levels, were selected and an orthogonal array layout of L16 was carried out. In the second experiment, Taguchi’s orthogonal array method of L27 was used to evaluate the effects of the different concentration of medium components. Taguchi’s signal–noise ratio and variance analysis were applied to determine the effect of the factors. After each experiment, verification studies were carried out using determined optimum conditions. Results The optimum conditions for incubation period, incubation temperature, initial pH, and medium determined as 72 h, 30°C, pH 9, and M4 medium, respectively. In the second experiment, soybean flour (5%), glucose (5%), KH2PO4 (0.3%), K2HPO4 (0.1%), MgSO4 (0.4%) were determined as the optimum conditions. The delta-endotoxin yield was elevated to 1559.25 μg mL−1 when the factors were adjusted to optimum level. Conclusion Optimization using the Taguchi method appeared to be a good choice for the overproduction of delta-endotoxin.

Metabolism of glucose-14C, pyruvate-14C, and mannitol-14C by Melampsora lini. II. Conversion to soluble products

1968 ◽  
Vol 46 (4) ◽  
pp. 453-460 ◽  
Author(s):  
D. Mitchell ◽  
Michael Shaw
Keyword(s):  
Pentose Phosphate Pathway ◽  
Tricarboxylic Acid Cycle ◽  
Rust Fungus ◽  
Tca Cycle ◽  
Tricarboxylic Acid ◽  
Pentose Phosphate ◽  
Soluble Carbohydrates ◽  
Melampsora Lini ◽  
Carbohydrate Fraction ◽  
The Tca Cycle

Mycelium of the flax rust fungus (Melampsora lini (Pers.) Lév.), grown on flax cotyledons in tissue culture, had a mean [Formula: see text]of 4.1 and a mean C6/C1 ratio of 0.14, measured after 4 hours in radioactive glucose. The C6/C1 ratio increased with time and also after treatment with 10−5 M 2,4-dinitrophenol. The relative labelling of the (80%) ethanol-soluble carbohydrates, and organic and amino acid fractions after incubation with glucose-1-, -2-, or -6-14C also indicated preferential release of C1 as 14CO2. Trehalose (unknown A) was tentatively identified in the carbohydrate fraction and was mildly radioactive after incubation of the mycelium with labelled glucose for 3 hours. The principal radioactive products of glucose in this fraction were two unknowns, B and C, which were tentatively identified as mannitol and arabitol. The labelling patterns were consistent with their formation from intermediates of the pentose phosphate pathway. The distribution of radioactivity derived from glucose in alanine, glutamate, and aspartate also indicated that hexose or triose units formed in the pentose phosphate pathway were converted to pyruvate, which either gave rise to alanine or was further oxidized in the tricarboxylic acid cycle. Incubation with pyruvate-1-, -2-, or -3-14C for 3 hours gave rise to 14CO2 and labelled alanine, glutamate, and aspartate in a manner consistent with the operation of the TCA cycle. Mannitol-1-6-14C was not metabolized to any appreciable extent in this period, but did give rise to 14CO2 and to several unidentified compounds in the carbohydrate fraction.

scholarly journals Genome analysis and avirulence gene cloning using a high-density RADseq linkage map of the flax rust fungus, Melampsora lini

BMC Genomics ◽  
2016 ◽  
Vol 17 (1) ◽  
Author(s):  
Claire Anderson ◽  
Muhammad Adil Khan ◽  
Ann-Maree Catanzariti ◽  
Cameron A. Jack ◽  
Adnane Nemri ◽  
...  
Keyword(s):  
Gene Cloning ◽  
Linkage Map ◽  
Genome Analysis ◽  
Rust Fungus ◽  
High Density ◽  
Avirulence Gene ◽  
Melampsora Lini

Growth and Aflaxtoxin Production by Aspergillus parasiticus in the Presence of Lactobacillus casei

1981 ◽  
Vol 44 (3) ◽  
pp. 211-212 ◽  
Author(s):  
S. M. EL-GENDY ◽  
E. H. MARTH
Keyword(s):  
Incubation Period ◽  
Lactobacillus Casei ◽  
Aspergillus Parasiticus ◽  
Mineral Salts ◽  
Total Growth ◽  
Better Than

When a mineral salts-glucose broth was inoculated simultaneously with Aspergillus parasiticus and Lactobacillus casei and incubated at 28 C for 10 days, (a) larger numbers of L. casei survived than when the bacterium was grown alone, (b) growth of A. parasiticus initially was more rapid but total growth during the incubation was comparable to that of the mold growing alone, (c) production of aflatoxin was less than when the mold grew alone and (d) degradation of aflatoxin by the mold was somewhat greater than when the mold grew alone. Growth of L. casei for 3 days before adding A. parasiticus resulted in (a) better survival of L. casei than when it grew alone but not better than when the two organisms were added to broth simultaneously, (b) slower growth of A. parasiticus than when it grew alone, (c) production of less aflatoxin than when the mold grew alone or when both organisms were added to broth simultaneously and (d) no apparent degradation of aflatoxin during the 10-day incubation period.

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