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.

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.

The fine structure of two rust fungi, Puccinia helianthi and Melampsora lini

1972 ◽  
Vol 50 (1) ◽  
pp. 231-240 ◽  
Author(s):  
Michael D. Coffey ◽  
Barry A. Palevitz ◽  
Paul J. Allen
Keyword(s):  
Rust Fungus ◽  
Fungal Species ◽  
Wall Material ◽  
Fungus Infection ◽  
Puccinia Helianthi ◽  
Melampsora Lini ◽  
Cytoplasmic Microtubules ◽  
Axenic Cultures ◽  
Specialized Structure ◽  
Parasitic Phase

The parasitic phase of the uredial stage of rust fungus infection is characterized by the formation of a specialized structure—the haustorium. The haustorial neck contains a band of darkly staining wall material, the length of which is dependent on the fungal species. In older infected tissues a collar sometimes develops at the site of penetration. In such cells, the host plasmalemma appears to double back on itself between the collar and the haustorial neck. The mitochondria of the haustorium contain many plate-like cristae and, less frequently, concentric whorls of membranes. Cytoplasmic microtubules are also observed in both the neck and body of the haustorium. Centriolar plaques are found appressed to the nuclear envelopes in both the hyphae and haustoria. They frequently consist of two amorphous regions which are connected by a rod-shaped, layered structure. The septal pore of the intercellular hyphae contains a plug of electron-transparent material. Surrounding it is a matrix of dense amorphous cytoplasm devoid of organelles which is bordered by a hemispherical array of microbodies containing crystals. Axenic cultures of Melampsora lini mycelium were examined and found to contain similar septal pore regions. These cultures also show some differences from the parasitic hyphae. The septa-associated microbodies in these cells appear to derive from an aggregate of tubular endoplasmic reticulum cisternae. Their mitochondria differ from those of the intercellular hyphae in having more and longer, plate-like cristae and a denser staining matrix. They therefore represent a type intermediate between those of the intercellular hyphae and the haustoria. The pseudoparenchymatous stroma of the axenic cultures contains cells of widely divergent ages. Some are young as determined by their dense cytoplasmic contents and large lobed nuclei. However, others are older, with large vacuoles and many lipid bodies. In some cases they have thick cell walls consisting of many layers.

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.

scholarly journals Site-specific methylation of adenine in the nuclear genome of a eucaryote, Tetrahymena thermophila.

1986 ◽  
Vol 6 (7) ◽  
pp. 2364-2370 ◽  
Author(s):  
G S Harrison ◽  
R C Findly ◽  
K M Karrer
Keyword(s):  
Heat Shock ◽  
Protein Gene ◽  
De Novo ◽  
Tetrahymena Thermophila ◽  
Nuclear Genome ◽  
Histone H4 ◽  
Ciliated Protozoan ◽  
Site Specific ◽  
Logarithmic Growth ◽  
I Gene

DNA in the polyploid macronucleus of the ciliated protozoan Tetrahymena thermophila contains the modified base N6-methyladenine. We identified two GATC sites which are methylated in most or all of the 45 copies of the macronuclear genome. One site is 2 kilobases 5' to the histone H4-I gene, and the other is 5 kilobases 3' to the 73-kilodalton heat shock protein gene. These sites are de novo methylated between 10 and 16 h after initiation of conjugation, during macronuclear anlage development. The methylation states of these two GATC sites and four other unmethylated GATC sites do not change in the DNA of cells cultured under conditions which change the activity of the genes, including logarithmic growth, starvation, and heat shock.

In vitro growth of wheat and flax rust fungi on complex and chemically defined media

1974 ◽  
Vol 52 (6) ◽  
pp. 1183-1195 ◽  
Author(s):  
A. Bose ◽  
Michael Shaw
Keyword(s):  
Liquid Medium ◽  
Aspartic Acid ◽  
Yeast Extract ◽  
Australian Isolate ◽  
Puccinia Graminis ◽  
Good Growth ◽  
Complex Media ◽  
Mineral Salts ◽  
Melampsora Lini

Growth from uredospores seeded in axenic culture is described for several races of Puccinia graminis Pers. f. sp. tritici (Erikss. and Henn.) and race 3 of Melampsora lini (Ehrenb.) Lév. on complex media containing peptone, yeast extract, and bovine serum albumin (BSA); and for an Australian isolate of Puccinia graminis, race 126-ANZ 6,7, and Melampsora lini, race 3, on chemically defined, liquid media.Of six North American isolates of Puccinia graminis only race 38 formed colonies approaching those of race 126-ANZ 6,7 in final size and general morphology on complex media. 5′AMP had no effect on the growth of 126-ANZ 6,7, but cyclic AMP inhibited growth after uredospore germination. Good growth and sporulation were obtained with 126-ANZ 6,7, but not with the other isolates tested, using a new, chemically defined liquid medium, sterilized by millipore filtration, and containing glucose, Czapek's minerals plus micronutrients, Ca2+, glucose and aspartic acid, glutathione, and cysteine. Uredospores produced in culture reinfected exposed mesophyll tissue, but not intact seedling leaves of wheat.Highly reproducible growth and sporulation of Melampsora lini, race 3, were obtained routinely on a solid medium containing Difco-Bacto agar, sucrose, Knop's minerals, micronutrients, yeast extract, peptone, and BSA. Vegetative cultures, capable of reinfecting the cut ends of surface-sterilized flax cotyledons, could be maintained indefinitely by subdivision before sporulation and transfer to the same medium minus BSA. Evidence is presented that BSA stimulated the development of colonies and the formation of uredospores. The mode of action of BSA is unknown, but it could not be replaced by putrescine.A new chemically defined, liquid medium containing sucrose, Knop's mineral salts, micronutrients, aspartic (or glutamic) acid, and cysteine supported the growth of colonies of Melampsora lini in a highly reproducible manner. The formation of uredospores and teliospores by these colonies was controlled by (a) the level of Ca2+ (as Ca(NO3)2∙4H2O), (b) the concentration of aspartic acid, and (c) the number of colonies per flask. At inoculum levels giving 40 to 60 colonies per flask, in media containing 8.5 mM Ca+ and 45 mM aspartic acid, uredospore formation occurred in 60 to 70% of the colonies. A decrease in the Ca2+ level to 4.25 mM, or a decrease in aspartic acid to 22.5 mM, or adjustment of the inoculum level to give about 10 colonies per flask each resulted in only infrequent sporulation. The uredospores produced in vitro infected intact, 1-week-old flax cotyledons in a normal manner.

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

Haustoria-like branches in axenic cultures of Puccinia graminis f. sp. tritici

1969 ◽  
Vol 47 (11) ◽  
pp. 1816-1817 ◽  
Author(s):  
P. G. Williams
Keyword(s):  
Stem Rust ◽  
Rust Fungus ◽  
Puccinia Graminis ◽  
Wheat Stem Rust ◽  
Artificial Culture ◽  
Axenic Cultures

Hyphae of the wheat stem rust fungus form short, lateral projections under conditions of artificial culture that are unfavorable for saprophytic growth. It is suggested that the structures are homologous with the haustoria of intercellular rust mycelium.

The effects of CO2 and membranes on sporulation in axenic cultures of flax rust

1985 ◽  
Vol 63 (8) ◽  
pp. 1418-1422 ◽  
Author(s):  
Rosalinda Boasson ◽  
Michael Shaw
Keyword(s):  
Membrane Surface ◽  
Volatile Substances ◽  
Melampsora Lini ◽  
Paraffin Oil ◽  
Air Space ◽  
Saran Wrap ◽  
Axenic Cultures ◽  
Diffusion Of Gases

Uredospore production by axenically grown flax rust (Melampsora lini (Ehrenb.) Lev.) was measured as carotenoids (extinction units at 458 nm) per milligram protein. Sporulation was not affected by raising (flushing with 1–5% (v/v) CO2 in air) or lowering (KOH well in culture flasks) the level of CO2 in the air space above the cultures. Significant (two- to four-fold) increases in sporulation occurred beneath impermeable membranes of Parafilm or Saran wrap placed on the surface of young (3 weeks from seeding) mycelial mats for 2 weeks. The stimulatory effect was confined strictly to those areas of the mycelial mats in contact with the membranes. Both Parafilm and Saran wrap were easily and cleanly peeled away from the mycelial mats. Permeable Unipore and HVHP membranes, to which the fungus adhered strongly, did not stimulate sporulation. The fungus did not adhere to Unipore or HVHP membranes treated with silicone or paraffin oil; membranes thus treated stimulated sporulation. The stimulatory effect of membranes on sporulation appears to depend on the nature of the contact between the membrane surface and the mycelium and to be unrelated to the effect of the membranes on the diffusion of gases or other volatile substances.

Sign in / Sign up

Export Citation Format

Share Document