Appearance of morphological (colonial) mutants in glucose-limited, continuous flow cultures of Fusarium graminearum A3/5

Wiebe, Marilyn G.; Trinci, Anthony P. J.; Cunliffe, Bryan; Robson, Geoffrey D.; Oliver, Steven G.

doi:10.1016/s0953-7562(09)80575-3

Cited by 26 publications

(29 citation statements)

References 11 publications

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“…Stock cultures were maintained as macroconidia at -70 "C in 20 ' % (v/v) glycerol. Inocula were prepared as described by Wiebe et al (1991).…”

Section: Methodsmentioning

confidence: 99%

“…Cultures were grown in a Braun Biostat M (2 1) fermenter (B. Braun Medical Ltd.) as described by Wiebe & Trinci (1991). Biomass retention in the fermenter vessel was monitored by taking dry weight measurements of culture samples both from inside the fermenter vessel and from the overflow.…”

Section: Methodsmentioning

confidence: 99%

“…Hyphal length (the longest hypha in a mycelial fragment) and hyphal growth unit length (a measure of hyphal branching; Trinci, 1974) were measured using a MeasureMouse graphics system (Analytical Measuring Systems) and an Amstrad PC1512 connected to a Nikon microscope (Wiebe & Trinci, 1991). As the majority of mycelia were unbranched or very sparsely branched, hyphal growth unit length measurements (made on mycelia with six or more branches) were not necessarily representative of the total population.…”

Section: Methodsmentioning

confidence: 99%

“…4). When A3/5 was grown in glucose-limited chemostat culture at a dilution rate of 0.06 h-l the population had a mean hyphal length (the longest hypha in a fragment) of 502 9 pm (mean & SE) and a hyphal growth unit length of 94 f 7 pm (Wiebe & Trinci, 1991). However, at the end of the present fermentation, the population had a mean hyphal length of 1104 f 69 pm (100 replicates) and a mean hyphal growth unit of 238 f 15 pm (25 replicates).…”

Section: Sporulation and Morphologymentioning

confidence: 99%

“…This phenomenon is now referred to as periodic selection (Novick & Szilard, 1950b;Dykhuizen & Hartl, 1983) and has been observed subsequently in populations of S. cerevisiae (Paquin & Adams, 1983a) and F. graminearam (Wiebe e t al., 1993). It is possible to study periodic selection in F. graminearam because it produces macroconidia (Wiebe & Trinci, 1991) which, although multinucleate, are homokaryotic (Miller, 1946). Since macroconidia are formed from uninucleate phialides, the nuclei in macroconidia harvested from a culture provide a sample of the nuclei present in the mycelial biomass.…”

Section: Introductionmentioning

confidence: 99%

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Evolution of Fusarium graminearum A3/5 grown in a glucose-limited chemostat culture at a slow dilution rate

Wiebe

Robson²,

Oliver³

et al. 1994

Microbiology

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The evolution of Fusarium graminearum A3/5 grown in a glucose-limited chemostat at a dilution rate of 0 0 5 h-l (doubling time of 13.9 h) was followed for 957 h or 69 generations. Periodic selection of advantageous mutants was monitored in the culture by determining increases and decreases in the concentration of cycloheximide-resistant macroconidia in the population. Six peaks in the concentration of cycloheximide-resistant macroconidia were observed representing five adaptive changes in the population; on average, an adaptive change occurred once every 148 _+ 22 h (mean & SE). The selection coefficient of strains present at the start of each increase in the concentration of cycloheximide-resistant macroconidia (i.e. after the establishment of a new advantageous strain) was determined relative to A3/5 and was found to increase progressively with time. When grown at a dilution rate of 0 0 5 h-l, the strain (A28-5) isolated from the last adaptive peak had a selection coefficient of 0.023 h-' relative to A3/5, but A28-S lost its selective advantage when grown at a dilution rate of about 0.11 h-' and was at a selective disadvantage when grown at a dilution rate higher than 0.1 1 h-l. The K,,, value (12 _+ 5 pM) for uptake of glucose by A 2 8 4 was significantly lower than that for A3/5. The spontaneous mutation rate from cycloheximide sensitivity to cycloheximide resistance was estimated to be 1.8 (k0.2) x generation-l.The culture initially contained about 1 x lo6 macroconidia ml-l but this decreased with time until, at about 800 h, the culture contained only about 1 x 104 macroconidia ml-l. No highly branched (colonial) mutants were observed in glucose-limited cultures at dilution rates of 0 0 5 h-l, even though the evolution of the population was followed for a further 1345 h in a second chemostat, making a total evolutionary period of 2207 h or 159 generations.h-l or 2.5 x

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“…Stock cultures were maintained as macroconidia at -70 "C in 20 ' % (v/v) glycerol. Inocula were prepared as described by Wiebe et al (1991).…”

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Sporulation and Morphologymentioning

confidence: 99%