Candida fennica: enhancement of protoplast formation and fusion

1992 ◽  
Vol 38 (8) ◽  
pp. 807-810 ◽  
Author(s):  
Carolina M. M. Andrade ◽  
Flavia M. Oliveira ◽  
Valter R. Linardi
Keyword(s):  
Key Words ◽  
Protoplast Fusion ◽  
Ultraviolet Light ◽  
Protoplast Regeneration ◽  
Protoplast Formation ◽  
Regeneration Frequency ◽  
Fusion Frequency ◽  
Auxotrophic Mutants ◽  
Enrichment Procedure ◽  
Dna Contents

Auxotrophic mutants were obtained by exposing Candida fennica FTPT/CCT-8903 to ultraviolet light and treating the cells with nystatin in an enrichment procedure. The mutants were used for protoplast fusion. The highest protoplast regeneration frequency was obtained when cells were treated with 10 mg NovoZym 234/mL in the presence of 0.8 M KCl for 60 min. Fusion frequency was in the range 5.84 × 10−5 to 7.2 × 10−5. Five prototrophic hybrid colonies, designated S9, S15, S17, S18, and S25, were isolated, and their DNA contents were measured. These measurements indicated that the S17 hybrid is haploid, S9 and S18 are polyploid, and S15 and S25 are both aneuploid. Key words: Candida fennica, nystatin, auxotrophic mutants, protoplast fusion.

Segregation of altered parental properties in fusions between Saccharomyces cerevisiae and the D-xylose fermenting yeasts Candida shehatae and Pichia stipitis

1992 ◽  
Vol 38 (12) ◽  
pp. 1233-1237 ◽  
Author(s):  
Abindra S. Gupthar
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Polyethylene Glycol ◽  
Gene Transfer ◽  
Key Words ◽  
Protoplast Fusion ◽  
Ethanol Tolerance ◽  
Pichia Stipitis ◽  
Candida Shehatae ◽  
Auxotrophic Mutants ◽  
Parental Type

A prototrophic strain of Saccharomyces cerevisiae CSIR Y190 MATa xyl−, resistant to high levels of ethanol, was hybridized with xylose-fermenting, auxotrophic mutants of Candida shehatae and Pichia stipitis through polyethylene glycol-induced protoplast fusion in an attempt to produce ethanol-tolerant, xylose-fermenting hybrids. Mononucleate fusants were obtained, but these dissociated into a mixture of parental-type segregants. Purified Candida- and Pichia-resembling segregants failed to acquire improved ethanol tolerance but expressed other novel properties of S. cerevisiae, suggesting that karyogamy was impaired after internuclear gene transfer. Key words: Pichia, Candida, Saccharomyces protoplast fusion.

scholarly journals Survival and mutant production induced by mutagenic agents in Metarhizium anisopliae

1995 ◽  
Vol 52 (3) ◽  
pp. 548-554 ◽  
Author(s):  
V. Kava - Cordeiro ◽  
E.A. Luna - Alves - Lima ◽  
J.L. Azevedo
Keyword(s):  
Gamma Radiation ◽  
Ultraviolet Light ◽  
Metarhizium Anisopliae ◽  
Entomopathogenic Fungus ◽  
Nitrous Acid ◽  
Wild Strain ◽  
Wild Type ◽  
Survival Curves ◽  
Auxotrophic Mutants ◽  
Morphological Mutants

A wild strain of Metarhizium anisopliae, an entomopathogenic fungus, was submitted to three mutagenic agents: gamma radiation, ultraviolet light and nitrous acid. Survival curves were obtained and mutants were selected using different mutagenic doses which gave 1 to 5% survival. Morphological and auxotrophic mutants were isolated. Morphological mutants were grouped in a class with yellow conidia and other with pale vinaceous conidia as opposed to the green wild type conidia. Auxotrophic mutants had requirements for vitamin and aminoacid biosynthesis. More than 58% of the total auxotrophk mutants required proline/aipnine. Gamma radiation showed to be the most efficient mutagenic agent giving 0.2% of auxotrophk mutants followed by ultraviolet light (0.12%) and nitrous acid (0.06%).The conidial colour and auxotrophk mutants isolated until now from M. anisopliae were reviewed.

GENETICS OF PHYTOPATHOGENIC FUNGI: VIRULENCE OF COLOR AND NUTRITIONALLY DEFICIENT MUTANTS OF PENICILLIUM ITALICUM AND PENICILLIUM DIGITATUM

1964 ◽  
Vol 42 (4) ◽  
pp. 429-436 ◽  
Author(s):  
L. Beraha ◽  
E. D. Garber ◽  
Ø. Strømnaes
Keyword(s):  
Ultraviolet Light ◽  
Parental Strain ◽  
Citrus Fruit ◽  
Phytopathogenic Fungi ◽  
Fruit Rot ◽  
Nutritional Requirements ◽  
Penicillium Italicum ◽  
Auxotrophic Mutants ◽  
Specific Alteration ◽  
Weakly Virulent

Prototrophic color and auxotrophic mutants of Penicillium italicum and P. digitatum, causal agents of citrus fruit rot, were obtained by irradiating conidia with ultraviolet light. Avirulent mutants caused a necrosis but not an obvious rot at the site of inoculation in orange rind. Avirulence was not necessarily associated with a specific alteration in the color of sporulating colonies or with the tested nutritional requirements. Supplementing necrotic lesions with the compounds required by the avirulent auxotrophic mutants enhanced growth but did not cause an obvious rot. Although heterocaryons of P. italicum involving avirulent auxotrophic strains were weakly virulent, the corresponding diploid strains were as virulent as the haploid prototrophic parental strain. Prototrophic segregants from the diploid strains were virulent. Avirulence was not related to the inability of the avirulent mutants to grow at the site of inoculation. It is probable that more than one locus may be responsible for the loss of virulence.

A visual indicator of heterokaryosis in Fusarium oxysporum from celery

1984 ◽  
Vol 62 (3) ◽  
pp. 540-545 ◽  
Author(s):  
John E. Puhalla
Keyword(s):  
Fusarium Oxysporum ◽  
Ultraviolet Light ◽  
Minimal Medium ◽  
Genetic Complementation ◽  
Wild Type ◽  
Uv Treatment ◽  
Formae Speciales ◽  
Auxotrophic Mutants ◽  
Pale Pink ◽  
Type Strains

Wild-type isolates of Fusarium oxysporum f. sp. apii (celery pathogens) were white or pale pink. Ultraviolet-light (UV) treatment of conidia, however, yielded stable orange mutants, which in turn gave rise to yellow and white mutants after a second UV treatment. Some pairings between these yellow and white mutants developed an orange line where they touched. This orange line developed only if the two mutants formed heterokaryons with each other. In contrast, attempts to demonstrate heterokaryons between complementary auxotrophic mutants on minimal medium failed. The color heterokaryon was a mosaic of homokaryotic and heterokaryotic cells, the latter being confined to the area of anastomosis between the two mutants. Genetic complementation was also confined to this area. In pairings among color mutants of five wild-type strains two vegetative (heterokaryon) compatibility (VC) groups were defined. VC groups in other formae spéciales of F. oxysporum should also be detectable by this method.

Déterminisme de la reproduction sexuée du Phaeosphaeria (Leptosphaeria) nodorum agent de la septoriose du blé. II. Action de la température et de la lumière

1992 ◽  
Vol 70 (8) ◽  
pp. 1563-1569 ◽  
Author(s):  
P. Halama ◽  
L. Lacoste
Keyword(s):  
Key Words ◽  
Ultraviolet Light ◽  
Early Stage ◽  
Leptosphaeria Nodorum ◽  
Near Ultraviolet ◽  
Phaeosphaeria Nodorum ◽  
Light Duration

Perithecial formation of Phaeosphaeria nodorum is obtained in vitro on sterilized wheat straws, under strict conditions of light and temperature. The absence of any reproductive form in the dark indicates photoinduction. The different parameters of light (duration, quality, and intensity) influence perithecial morphogenesis. A 12-h photoperiod, near ultraviolet light (300 nm < λ < 400 nm), and intensities of 400 and 600 μW/cm2 are the most favourable conditions for perithecial differentiation. The perithecial production occurs best at 10 °C, is markedly reduced at 14 °C, and absent above 14 °C. Light and temperature have a sequential influence on the successive stages of perithecial development. Whereas primordial formation is photoinhibited and cryostimulated, transformation to the early stage of perithecial development is photoinduced and not affected by temperatures of 10 and 18 °C. The subsequent stages up to ascogenesis are photostimulated and cryoinduced, and ascosporogenesis is photoindependent and cryostimulated. Key words: Phaeosphaeria, Leptosphaeria nodorum, perithecia, light, temperature.

Trichoderma protoplast fusion: a tool for improving biocontrol agents

1990 ◽  
Vol 36 (1) ◽  
pp. 6-9 ◽  
Author(s):  
S. Pe'er ◽  
I. Chet
Keyword(s):  
Cell Wall ◽  
Key Words ◽  
Protoplast Fusion ◽  
Trichoderma Harzianum ◽  
Pathogenic Fungus ◽  
Sclerotium Rolfsii ◽  
Pathogenic Fungi ◽  
Damping Off ◽  
Dual Cultures ◽  
Young Thalli

Protoplasts from two auxotrophic mutants of Trichoderma harzianum Rifai (ATCC 32173), obtained from young thalli following cell wall digestion by NovoZym 234, were fused in 33% PEG suspended in 10 mM Tris-HCl and 10 mM CaCl2, pH 7.5. The frequency of fusion between lysine- and arginine-requiring auxotrophs resulting in prototrophic strains was about 5%. These prototrophic strains were classified into parental and nonparental types. Colonies developed from single conidia of the nonparental phenotype exhibited prototrophic parental or recombinant phenotypes. The ability of both prototrophic and parental strains to overgrow the soil-borne pathogenic fungi Rhizoctonia solani, Sclerotium rolfsii, and Pythium aphanidermatum in dual cultures was used to evaluate their antagonistic capability. The antagonistic abilities of the prototrophic strains were found to vary with each pathogenic fungus. The prototrophic strain A2 overgrew all the pathogenic fungi more rapidly than the parental strains. Strain A2 effectively controlled Rhizoctonia damping-off of cotton seedlings, in the greenhouse, when compared with the parental strains. Protoplast fusion appears to be a useful tool for combining desirable traits from parental strains to produce improved biocontrol strains. Key words: Trichoderma harzianum, biocontrol, protoplast fusion.

Sign in / Sign up

Export Citation Format

Share Document