A nonsclerotial pathogenic mutant of Sclerotinia sclerotiorum

1989 ◽  
Vol 35 (4) ◽  
pp. 517-520 ◽  
Author(s):  
R. Vincent Miller ◽  
Eugene J. Ford ◽  
David C. Sands
Keyword(s):  
Ultraviolet Light ◽  
Plant Species ◽  
Sclerotinia Sclerotiorum ◽  
Parental Strain ◽  
Wild Type ◽  
Physiological Studies ◽  
Sclerotial Development

A nonsclerotial mutant of Sclerotinia sclerotiorum was produced by mutagenesis with 8-methoxypsoralen and ultraviolet light. The mutant, SL-1, failed to produce sclerotia on artificial media, infested grain, or on infected plants. The mutant remained pathogenic to eight plant species susceptible to the wild-type parental strain of the fungus. The mutant, SL-1, is potentially useful for physiological studies on sclerotial development and for investigation of its potential for biological weed control.Key words: Sclerotinia, mutant, sclerotialess, biocontrol, weeds.

scholarly journals Increase in Endogenous and Exogenous Cyclic AMP Levels Inhibits Sclerotial Development in Sclerotinia sclerotiorum

1998 ◽  
Vol 64 (7) ◽  
pp. 2539-2544 ◽  
Author(s):  
Jeffrey A. Rollins ◽  
Martin B. Dickman
Keyword(s):  
Cyclic Amp ◽  
Sclerotinia Sclerotiorum ◽  
Growth And Development ◽  
Mycelial Growth ◽  
Dependent Manner ◽  
Wild Type ◽  
Concentration Dependent Manner ◽  
Sclerotial Development ◽  
Camp Levels ◽  
Methyl Xanthine

ABSTRACT Growth and development of a wild-type Sclerotinia sclerotiorum isolate were examined in the presence of various pharmacological compounds to investigate signal transduction pathways that influence the development of sclerotia. Compounds known to increase endogenous cyclic AMP (cAMP) levels in other organisms by inhibiting phosphodiesterase activity (caffeine and 3-isobutyl-1-methyl xanthine) or by activating adenylate cyclase (NaF) reduced or eliminated sclerotial development in S. sclerotiorum. Growth in the presence of 5 mM caffeine correlated with increased levels of endogenous cAMP in mycelia. In addition, incorporation of cAMP into the growth medium decreased or eliminated the production of sclerotia in a concentration-dependent manner and increased the accumulation of oxalic acid. Inhibition of sclerotial development was cAMP specific, as exogenous cyclic GMP, AMP, and ATP did not influence sclerotial development. Transfer of developing cultures to cAMP-containing medium at successive time points demonstrated that cAMP inhibits development prior to or during sclerotial initiation. Together, these results indicate that cAMP plays a role in the early transition between mycelial growth and sclerotial development.

scholarly journals Novel Secretory Protein Ss-Caf1 of the Plant-Pathogenic Fungus Sclerotinia sclerotiorum Is Required for Host Penetration and Normal Sclerotial Development

2014 ◽  
Vol 27 (1) ◽  
pp. 40-55 ◽  
Author(s):  
Xueqiong Xiao ◽  
Jiatao Xie ◽  
Jiasen Cheng ◽  
Guoqing Li ◽  
Xianhong Yi ◽  
...  
Keyword(s):  
Cell Death ◽  
Sclerotinia Sclerotiorum ◽  
Type Strain ◽  
Wild Type Strain ◽  
Tobacco Rattle Virus ◽  
Secretory Protein ◽  
Host Cells ◽  
Wild Type ◽  
Appressorium Formation ◽  
Sclerotial Development

To decipher the mechanism of pathogenicity in Sclerotinia sclerotiorum, a pathogenicity-defective mutant, Sunf-MT6, was isolated from a T-DNA insertional library. Sunf-MT6 could not form compound appressorium and failed to induce lesions on leaves of rapeseed though it could produce more oxalic acid than the wild-type strain. However, it could enter into host tissues via wounds and cause typical necrotic lesions. Furthermore, Sunf-MT6 produced fewer but larger sclerotia than the wild-type strain Sunf-M. A gene, named Ss-caf1, was disrupted by T-DNA insertion in Sunf-MT6. Gene complementation and knockdown experiments confirmed that the disruption of Ss-caf1 was responsible for the phenotypic changes of Sunf-MT6. Ss-caf1 encodes a secretory protein with a putative Ca2+-binding EF-hand motif. High expression levels of Ss-caf1 were observed at an early stage of compound appressorium formation and in immature sclerotia. Expression of Ss-caf1 without signal peptides in Nicotiana benthamiana via Tobacco rattle virus-based vectors elicited cell death. These results suggest that Ss-caf1 plays an important role in compound appressorium formation and sclerotial development of S. sclerotiorum. In addition, Ss-Caf1 has the potential to interact with certain host proteins or unknown substances in host cells, resulting in subsequent host cell death.

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.

scholarly journals RNase III Is Required for Actinomycin Production in Streptomyces antibioticus

2013 ◽  
Vol 79 (20) ◽  
pp. 6447-6451 ◽  
Author(s):  
Jung-Hoon Lee ◽  
Marcha L. Gatewood ◽  
George H. Jones
Keyword(s):  
Parental Strain ◽  
Insertional Mutagenesis ◽  
Southern Blotting ◽  
Antibiotic Production ◽  
Streptomyces Coelicolor ◽  
Production Medium ◽  
Wild Type ◽  
Rnase Iii ◽  
Content Type ◽  
Streptomyces Antibioticus

ABSTRACTUsing insertional mutagenesis, we have disrupted the RNase III gene,rnc, of the actinomycin-producing streptomycete,Streptomyces antibioticus. Disruption was verified by Southern blotting. The resulting strain grows more vigorously than its parent on actinomycin production medium but produces significantly lower levels of actinomycin. Complementation of therncdisruption with the wild-typerncgene fromS. antibioticusrestored actinomycin production to nearly wild-type levels. Western blotting experiments demonstrated that the disruptant did not produce full-length or truncated forms of RNase III. Thus, as is the case inStreptomyces coelicolor, RNase III is required for antibiotic production inS. antibioticus. No differences in the chemical half-lives of bulk mRNA were observed in a comparison of theS. antibioticus rncmutant and its parental strain.

scholarly journals Identification of novel mutations contributing to azole tolerance of Aspergillus fumigatus through in vitro exposure to tebuconazole

2020 ◽  
Author(s):  
Takahito Toyotome ◽  
Kenji Onishi ◽  
Mio Sato ◽  
Yoko Kusuya ◽  
Daisuke Hagiwara ◽  
...  
Keyword(s):  
Aspergillus Fumigatus ◽  
Parental Strain ◽  
Resistance Mechanisms ◽  
Wild Type ◽  
Genome Sequences ◽  
Novel Mutations ◽  
Mutant Selection ◽  
Synonymous Mutations ◽  
Azole Tolerance

AbstractAzole resistance of Aspergillus fumigatus is a global problem. The major resistant mechanism is a cyp51A alteration such as mutation(s) in the gene and the acquisition of a tandem repeat in the promoter. Although other azole tolerances and resistant mechanisms such as hmg1 mutation are known, few reports describe studies elucidating non-cyp51A resistance mechanisms. This study explored genes contributing to azole tolerance in A. fumigatus by in vitro mutant selection with tebuconazole, an azole fungicide. After three-round selection, we obtained four isolates with low susceptibility to tebuconazole. These isolates also showed low susceptibility to itraconazole and voriconazole. Comparison of the genome sequences of the obtained isolates and the parental strain revealed a non-synonymous mutation in MfsD (Afu1g11820, R337L mutation) in all isolates. Furthermore, non-synonymous mutations in AgcA (Afu7g05220, E535Stop mutation), UbcD (Afu3g06030, T98K mutation), AbcJ (Afu3g12220, G297E mutation), and RttA (Afu7g04740, A83T mutation), a protein responsible for tebuconazole tolerance, were found in at least one isolate. Clarification by constructing the MfsD R337L mutant suggests that the mutation contributes to azole tolerance. Disruption of the agcA gene and reconstruction of the A83T point mutation in RttA led to decreased susceptibility to azoles. The reversion of T98K mutation to wild type in UbcD led to the level of azole susceptibility comparable to the parental strain. These results suggest that these mutations contribute to lowered susceptibility to medical azoles and to agricultural azole fungicides.

scholarly journals Peroxysomal Carnitine Acetyl Transferase Influences Host Colonization Capacity in Sclerotinia sclerotiorum

2013 ◽  
Vol 26 (7) ◽  
pp. 768-780 ◽  
Author(s):  
D. Liberti ◽  
J. A. Rollins ◽  
K. F. Dobinson
Keyword(s):  
Fatty Acids ◽  
Oxalic Acid ◽  
Sclerotinia Sclerotiorum ◽  
Magnaporthe Grisea ◽  
Glyoxylate Cycle ◽  
Wild Type ◽  
Transcript Accumulation ◽  
Acetyl Coa ◽  
Host Colonization ◽  
Carnitine Acetyl Transferase

In lower eukaryotes, the glyoxylate cycle allows cells to utilize two-carbon compounds when simple sugars are not available. In filamentous fungi, glyoxylate metabolism is coupled with β-oxidation of fatty acids, and both are localized to ubiquitous eukaryotic organelles called peroxisomes. Acetyl coenzyme A (acetyl-CoA) produced during β-oxidation is transported via the cytosol into mitochondria for further metabolism. A peroxisomal-specific pathway for acetyl-CoA transport requiring peroxisomal carnitine acetyl transferase (CAT) activity has been identified in Magnaporthe grisea peroxisomes. Here, we report that a Sclerotinia sclerotiorum ortholog of the M. grisea peroxisomal CAT-encoding gene Pth2 (herein designated Ss-pth2) is required for virulence-associated host colonization. Null (ss-pth2) mutants, obtained by in vitro transposon mutagenesis, failed to utilize fatty acids, acetate, or glycerol as sole carbon sources for growth. Gene expression analysis of these mutants showed altered levels of transcript accumulation for glyoxylate cycle enzymes. Ss-pth2 disruption also affected sclerotial, apothecial, and appressorial development and morphology, as well as oxalic acid accumulation when cultured with acetate or oleic acid as sole carbon nutrient sources. Although mutants were able to penetrate and initially colonize host tissue, subsequent colonization was impaired. Genetic complementation with the wild-type Ss-pth2 restored wild-type virulence phenotypes. These findings suggest an essential role in S. sclerotiorum for the peroxisomal metabolic pathways for oxalic acid synthesis and host colonization.

scholarly journals Morphological and molecular aspects of sclerotial development in the phytopathogenic fungus Sclerotinia sclerotiorum

2019 ◽  
Vol 229 ◽  
pp. 126326 ◽  
Author(s):  
Bruna Sousa Melo ◽  
Aline Raquel Voltan ◽  
Walquiria Arruda ◽  
Fabyano Alvares Cardoso Lopes ◽  
Raphaela Castro Georg ◽  
...  
Keyword(s):  
Sclerotinia Sclerotiorum ◽  
Phytopathogenic Fungus ◽  
Molecular Aspects ◽  
Sclerotial Development

Low-level iron-dependent mutants ofListeria monocytogenesand their virulence in macrophages

2003 ◽  
Vol 49 (2) ◽  
pp. 78-84 ◽  
Author(s):  
Philippe Andre ◽  
Stéphanie Oberle ◽  
Véronique Specklin ◽  
Yves Lombard ◽  
Dominique Jean-Marie Vidon
Keyword(s):  
Listeria Monocytogenes ◽  
Cell Line ◽  
Parental Strain ◽  
Wild Strain ◽  
Wild Type ◽  
Macrophage Cell Line ◽  
Macrophage Cell ◽  
Macrophage Cells ◽  
J774 Macrophage ◽  
Iron Requirement

Listeria monocytogenes is an opportunistic intracellular pathogen capable of growth within phagocytic cells that requires iron for growth and virulence expression. In the presence of an appropriate concentration of tropolone, an iron-chelating agent, growth of L. monocytogenes is completely inhibited. However, this inhibition can be relieved by addition of dopamine, norepinephrine, or ferric citrate. By selection on streptonigrin medium supplemented with tropolone and norepinephrine, we have obtained two spontaneous mutants, Lm-8 and Lm-15, with the same iron dependence but lower iron dependence than the wild-type Lm-B38. The association between iron requirement and virulence of the two mutants and the wild type was studied in the J774 macrophage cell line. One hour after phagocytosis by the J774 macrophage cell line, the two mutants and the parental strain displayed no difference in the number of phagocytosed bacteria. Twenty-four hours after phagocytosis, the number of bacteria within the surviving macrophages was identical for the wild strain and the two clones. However, only 40% of macrophage cells infected with Lm-8 and 90% of those infected with Lm-15 were alive after 24 h in comparison with macrophage cells infected with the parental strain Lm-B38. These data demonstrate that there is no direct correlation between iron requirement and virulence of L. monocytogenes in the J774 macrophage cell line.Key words: Listeria monocytogenes, iron, virulence, macrophages.

scholarly journals Developmental mutants in a homothallic strain of Physarum polycephalum

1973 ◽  
Vol 21 (1) ◽  
pp. 79-86 ◽  
Author(s):  
A. E. Wheals
Keyword(s):  
Synergistic Effect ◽  
Ultraviolet Light ◽  
Mating Type ◽  
Physarum Polycephalum ◽  
High Efficiency ◽  
Type A ◽  
Wild Type ◽  
Developmental Transition ◽  
Developmental Mutants

SUMMARYA derivative line of the homothallic Colonia strain of Physarum polycephalum has been isolated which produces plasmodia with high efficiency within clones of amoebae. Using the synergistic effect of ultraviolet light and caffeine, mutants of this line have been isolated which fail to undergo the developmental transition between haploid amoebae and diploid plasmodia (apt mutants). They are isolated by selecting for amoebae which fail to produce plasmodia within clones. Complementation tests of four mutants have shown that they are mutants of four different loci and they are recessive to wild-type. A further analysis of one mutant reveals that the apt-1 locus is unlinked to three other known markers. Crosses of this mutant with heterothallic strains yield progeny which are homothallic indicating that the lesion is not a revertant from a homothallic to a heterothallic mating-type. The use of this system in isolating developmental mutants is discussed.

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