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.

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.

The intracellular reserve polysaccharide of Clostridium pasteurianum

1977 ◽  
Vol 23 (8) ◽  
pp. 947-953 ◽  
Author(s):  
A. G. Darvill ◽  
M. A. Hall ◽  
J. P. Fish ◽  
J. G. Morris
Keyword(s):  
Mutant Strain ◽  
Minimal Medium ◽  
Clostridium Pasteurianum ◽  
Wild Type ◽  
Methylation Analysis ◽  
Glucose Content ◽  
Glucose Minimal Medium ◽  
Intracellular Polysaccharide ◽  
Type Strains ◽  
Negative Mutant

An amylopectinlike polysaccharide (granulose) was the only glucan produced in significant quantities by six wild-type strains of Clostridium pasteurianum grown in glucose minimal medium. The intracellular polysaccharide granules laid down before sporulation contained only this amylopectin. No intracellular dextran was discovered in these wild-type strains, nor in a granulose-negative mutant strain of C. pasteurianum possessing an ADP glucose pyrophosphorylase (EC 2.7.7.27) but lacking a granulose synthase (i.e. ADPglucose-α-1,4-glucan glucosyl transferase, EC 2.4.1.21). Furthermore, methylation analysis demonstrated that (1 → 6) linked α-D-glucose units accounted for less than 2% of the entire glucose content of these organisms.

Comparing vegetative compatibility and protein banding patterns for identification of Fusarium oxysporum f.sp. apii race 2

1991 ◽  
Vol 37 (9) ◽  
pp. 669-674 ◽  
Author(s):  
K. F. Toth ◽  
M. L. Lacy
Keyword(s):  
Fusarium Oxysporum ◽  
Polyacrylamide Gel Electrophoresis ◽  
Vegetative Compatibility ◽  
Wild Type ◽  
Banding Patterns ◽  
Formae Speciales ◽  
Compatibility Group ◽  
Race 1 ◽  
Pathogenicity Tests ◽  
Race 2

Vegetative compatibility grouping and electrophoretic separation of total proteins were compared as possible techniques for identifying isolates of Fusarium oxysporum f.sp. apii race 2, the cause of fusarium yellows of celery. Vegetative compatibility grouping was determined by pairing chlorate-tolerant, nitrate-nonutilizing mutants on a minimal medium containing nitrate as the sole nitrogen source. Heterokaryon formation, which resulted in wild-type growth, occurred only between mutants from vegetatively compatible isolates. All isolates of F. oxysporum f.sp. apii race 2 examined were placed within a unique vegetative compatibility group that excluded F. oxysporum f.sp. apii race 1 and the 11 other formae speciales of F. oxysporum tested. Few differences were observed in protein banding patterns among isolates of F. oxysporum f.sp. apii race 2, F. oxysporum f.sp. apii race 1, 11 other formae speciales of F. oxysporum, and 2 formae speciales of F. solani on 12% polyacrylamide gels. No banding pattern unique to F. oxysporum f.sp. apii race 2 was observed. Vegetative compatibility grouping could be accomplished more rapidly than greenhouse pathogenicity tests and more accurately identified race 2 isolates in a population of isolates of F. oxysporum from muck soils than did greenhouse pathogenicity tests or electrophoretic protein banding patterns. Key words: celery, fusarium yellows, nitrate-nonutilizing mutants, polyacrylamide gel electrophoresis.

scholarly journals Suppressors of recB mutations in Salmonella typhimurium.

Genetics ◽  
1994 ◽  
Vol 138 (1) ◽  
pp. 11-28 ◽  
Author(s):  
N R Benson ◽  
J Roth
Keyword(s):  
Escherichia Coli ◽  
Salmonella Typhimurium ◽  
Mitomycin C ◽  
Ultraviolet Light ◽  
Genetic Background ◽  
Deletion Mutants ◽  
Wild Type ◽  
Insertion And Deletion ◽  
Type Strains ◽  
Tandem Duplications

Abstract Using a screen that directly assesses transductional proficiency, we have isolated suppressors of recB mutations in Salmonella typhimurium. The alleles of sbcB reported here are phenotypically distinct from those isolated in Escherichia coli in that they restore recombination proficiency (Rec+), resistance to ultraviolet light (UVR), and mitomycin C resistance (MCR) in the absence of an accompanying sbcCD mutation. In addition the sbcB alleles reported here are co-dominant to sbcB+. We have also isolated insertion and deletion mutants of the sbcB locus. These null mutations suppress only the UVS phenotype of recB mutants. We have also isolated sbcCD mutations, which map near proC. These sbcCD mutations increase the viability, recombination proficiency and MCR of both the transductional recombination suppressors (sbcB1 & sbcB6) and the sbcB null mutations. S. typhimurium recB sbcB1 sbcCD8 strains are 15-fold more recombination proficient than wild-type strains. The increase in transductants in these strains is accompanied by a loss of abortive transductants suggesting that these fragments are accessible to the mutant recombination apparatus. Using tandem duplications, we have constructed sbcB merodiploids and found that, in a recB mutant sbcCD+ genetic background, the sbcB+ allele is dominant to sbcB1 for transductional recombination but co-dominant for UVR and MCR. However, in a recB sbcCD8 genetic background, the sbcB1 mutation is co-dominant to sbcB+ for all phenotypes. Our results lead us to suggest that the SbcB and SbcCD proteins have roles in RecBCD-dependent recombination.

Classification of strains of Fusarium oxysporum on the basis of vegetative compatibility

1985 ◽  
Vol 63 (2) ◽  
pp. 179-183 ◽  
Author(s):  
John E. Puhalla
Keyword(s):  
Fusarium Oxysporum ◽  
Radial Growth ◽  
Minimal Medium ◽  
Evolutionary Model ◽  
Vegetative Compatibility ◽  
Wild Type ◽  
Vegetative Compatibility Groups ◽  
Heterokaryon Formation ◽  
Nit Mutants

Twenty-one strains of Fusarium oxysporum were classified on the basis of vegetative compatibility or the ability to form hetcrokaryons. Heterokaryon formation was demonstrated by pairing mutants that were unable to reduce nitrate. These "nit mutants" could be recovered without mutagen treatment from selective media containing KClO3. On Czapek's minimal medium the nit mutants had a radial growth rate like that of wild type, but their colonies were very thin. Two genetically different nit mutants were recovered in each of the 21 strains and paired in all combinations on minimal medium. Heterokaryon formation was indicated by dense growth where the two mutant colonies touched. As a result, 16 vegetative compatibility groups (VCGs) were defined such that only strains in the same VCG were vegetatively compatible. In no case was a strain assignable to more than one VCG. There was some evidence for a correlation between VCG and forma specialis. An evolutionary model to explain this correlation is proposed. Vegetative compatibility may be a fast and easy way to distinguish pathotypes of F. oxysporum.

scholarly journals The Lipid Lysyl-Phosphatidylglycerol Is Present in Membranes of Rhizobium tropici CIAT899 and Confers Increased Resistance to Polymyxin B Under Acidic Growth Conditions

2007 ◽  
Vol 20 (11) ◽  
pp. 1421-1430 ◽  
Author(s):  
Christian Sohlenkamp ◽  
Kanaan A. Galindo-Lagunas ◽  
Ziqiang Guan ◽  
Pablo Vinuesa ◽  
Sally Robinson ◽  
...  
Keyword(s):  
Sinorhizobium Meliloti ◽  
Minimal Medium ◽  
Polymyxin B ◽  
Growth Conditions ◽  
Membrane Lipid ◽  
Low Ph ◽  
Wild Type ◽  
Rhizobium Tropici ◽  
Gram Negative ◽  
Inducible Genes

Lysyl-phosphatidylglycerol (LPG) is a well-known membrane lipid in several gram-positive bacteria but is almost unheard of in gram-negative bacteria. In Staphylococcus aureus, the gene product of mprF is responsible for LPG formation. Low pH-inducible genes, termed lpiA, have been identified in the gram-negative α-proteobacteria Rhizobium tropici and Sinorhizobium medicae in screens for acid-sensitive mutants and they encode homologs of MprF. An analysis of the sequenced bacterial genomes reveals that genes coding for homologs of MprF from S. aureus are present in several classes of organisms throughout the bacterial kingdom. In this study, we show that the expression of lpiA from R. tropici in the heterologous hosts Escherichia coli and Sinorhizobium meliloti causes formation of LPG. A wild-type strain of R. tropici forms LPG (about 1% of the total lipids) when the cells are grown in minimal medium at pH 4.5 but not when grown in minimal medium at neutral pH or in complex tryptone yeast (TY) medium at either pH. LPG biosynthesis does not occur when lpiA is deleted and is restored upon complementation of lpiA-deficient mutants with a functional copy of the lpiA gene. When grown in the low-pH medium, lpiA-deficient rhizobial mutants are over four times more susceptible to the cationic peptide polymyxin B than the wild type.

scholarly journals Identification ofvib-1, a Locus Involved in Vegetative Incompatibility Mediated byhet-cinNeurospora crassa

Genetics ◽  
2002 ◽  
Vol 162 (1) ◽  
pp. 89-101 ◽  
Author(s):  
Qijun Xiang ◽  
N Louise Glass
Keyword(s):  
Acid Phosphatase ◽  
Recognition System ◽  
Deletion Mutants ◽  
Wild Type ◽  
Vegetative Incompatibility ◽  
Death Rates ◽  
Self Recognition ◽  
Allelic Differences ◽  
Native Gel ◽  
Type Strains

AbstractA non-self-recognition system called vegetative incompatibility is ubiquitous in filamentous fungi and is genetically regulated by het loci. Different fungal individuals are unable to form viable heterokaryons if they differ in allelic specificity at a het locus. To identify components of vegetative incompatibility mediated by allelic differences at the het-c locus of Neurospora crassa, we isolated mutants that suppressed phenotypic aspects of het-c vegetative incompatibility. Three deletion mutants were identified; the deletions overlapped each other in an ORF named vib-1 (vegetative incompatibility blocked). Mutations in vib-1 fully relieved growth inhibition and repression of conidiation conferred by het-c vegetative incompatibility and significantly reduced hyphal compartmentation and death rates. The vib-1 mutants displayed a profuse conidiation pattern, suggesting that VIB-1 is a regulator of conidiation. VIB-1 shares a region of similarity to PHOG, a possible phosphate nonrepressible acid phosphatase in Aspergillus nidulans. Native gel analysis of wild-type strains and vib-1 mutants indicated that vib-1 is not the structural gene for nonrepressible acid phosphatase, but rather may regulate nonrepressible acid phosphatase activity.

scholarly journals HET-E and HET-D Belong to a New Subfamily of WD40 Proteins Involved in Vegetative Incompatibility Specificity in the Fungus Podospora anserina

Genetics ◽  
2002 ◽  
Vol 161 (1) ◽  
pp. 71-81
Author(s):  
Eric Espagne ◽  
Pascale Balhadère ◽  
Marie-Louise Penin ◽  
Christian Barreau ◽  
Béatrice Turcq
Keyword(s):  
Genetic Difference ◽  
Podospora Anserina ◽  
Wild Type ◽  
Incompatible Interaction ◽  
Vegetative Incompatibility ◽  
Repeat Domain ◽  
Upper Face ◽  
E1a Gene ◽  
Type Strains ◽  
Wd40 Repeats

Abstract Vegetative incompatibility, which is very common in filamentous fungi, prevents a viable heterokaryotic cell from being formed by the fusion of filaments from two different wild-type strains. Such incompatibility is always the consequence of at least one genetic difference in specific genes (het genes). In Podospora anserina, alleles of the het-e and het-d loci control heterokaryon viability through genetic interactions with alleles of the unlinked het-c locus. The het-d2Y gene was isolated and shown to have strong similarity with the previously described het-e1A gene. Like the HET-E protein, the HET-D putative protein displayed a GTP-binding domain and seemed to require a minimal number of 11 WD40 repeats to be active in incompatibility. Apart from incompatibility specificity, no other function could be identified by disrupting the het-d gene. Sequence comparison of different het-e alleles suggested that het-e specificity is determined by the sequence of the WD40 repeat domain. In particular, the amino acids present on the upper face of the predicted β-propeller structure defined by this domain may confer the incompatible interaction specificity.

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