Use of mutants to establish (+)-scytalone as an intermediate in melanin biosynthesis by Verticillium dahliae

1976 ◽  
Vol 22 (6) ◽  
pp. 787-799 ◽  
Author(s):  
A. A. Bell ◽  
J. E. Puhalla ◽  
W. J. Tolmsoff ◽  
R. D. Stipanovic
Keyword(s):  
Physical Properties ◽  
Verticillium Dahliae ◽  
Recessive Gene ◽  
The Other ◽  
Thielaviopsis Basicola ◽  
Single Recessive Gene ◽  
Wild Type ◽  
Melanin Biosynthesis ◽  
In The Wild ◽  
Verticillium Dahliae Kleb

Melanin biosynthesis in Verticillium dahliae Kleb. was studied with mutants deficient for normal black melanin or for production of microsclerotia. Seven genetically different mutants had apparent blocks in melanin biosynthesis. Four mutants (brm-I to -4) produced brown microsclerotia and extruded pigments into media; three (alm-1 to -3) produced albino microsclerotia. Other mutants produced no microsclerotia (nms) or had greatly reduced numbers of microsclerotia (rms). Mutation alm-1 was due to a single recessive gene; the other melanin-deficient characters were recessive but their genetic bases were not determined. Cultures of the brown mutants brm-1 and -3 extruded and accumulated a metabolite that blackened the albino microsclerotia of alm-1 to -3. The metabolite was identified as (+)-scytalone (3, 4-dihydro-3, 6, 8-trihydroxy-1(2H)naphthalenone). Pigment formed by alm-1 microsclerotia from (+)-scytalone had chemical and physical properties identical with those of melanin in the wild-type fungus. (+)-Scytalone was produced and converted to melanin by microsclerotia but not by conidia or hyphae. Conversion of (+)-scytalone to melanin appeared to involve two or more enzymes and probably involved conversions to 1, 3, 8-trihydroxynaphthalene and 1, 8-dihydroxynaphthalene. Albino mutants of Thielaviopsis basicola, Drechslera sorokiniana, Pleospora infectoria (Alternaria), Ulocladium sp., and Curvularia sp. also converted scytalone to pigments indistinguishable from the melanins found in their respective wild types. Scytalone melanin may be common in fungi with dark brown or black pigments.

scholarly journals Defect in Brnym1, a magnesium-dechelatase protein, causes a stay-green phenotype in an EMS-mutagenized Chinese cabbage (Brassica campestris L. ssp. pekinensis) line

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Nan Wang ◽  
Yun Zhang ◽  
Shengnan Huang ◽  
Zhiyong Liu ◽  
Chengyu Li ◽  
...  
Keyword(s):  
Chinese Cabbage ◽  
Focal Point ◽  
Recessive Gene ◽  
Base Substitution ◽  
Wild Type ◽  
Causal Gene ◽  
Stay Green ◽  
Leaf Yellowing ◽  
In The Wild ◽  
Green Mutant

AbstractLeaf color is an important target trait in Chinese cabbage breeding programs. Leaf yellowing may reduce crop commercial and nutritional values. Some plants with the “stay-green” trait maintain leaf greenness during senescence and even after death. Stay-green Chinese cabbage may be a focal point of future breeding projects because it could improve crop quality and yield and prolong shelf life. A new stay-green mutant, non-yellowing mutant 1 (nym1), was identified in Chinese cabbage derived from an ethyl methane sulfonate (EMS)-mutagenized population. The mutant had stay-green characteristics and a higher chlorophyll content than the wild-type during leaf senescence. The stay-green trait in the mutant Chinese cabbage was controlled by the recessive gene Brnym1. MutMap and KASP analyses showed that Brnym1 (BraA03g050600.3C) encodes an mg-dechelatase (SGR protein), which might be the causal gene of the mutation in Chinese cabbage. A nonsynonymous single nucleotide base substitution (G to A) in the third exon of Brnym1 caused an amino acid substitution from L to F in the highly conserved domain of the magnesium-dechelatase. Ectopic overexpression showed that the BrNYM1 gene of wild-type Chinese cabbage complemented the SGR-defective stay-green mutant nye1-1 of Arabidopsis. The magnesium-dechelatase activity in the nym1 mutant was significantly downregulated compared to that in the wild type. Brnym1 was relatively upregulated in the mutant during late senescence, and BrNYM1 was localized to the chloroplasts. These results indicate that Brnym1 (BraA03g050600.3C) is the causal gene of the stay-green mutation and could be of particular significance in the genetic improvement of Chinese cabbage.

Ultrastructural and chemical distinction of melanins formed by Verticillium dahliae from (+)-scytalone, 1,8-dihydroxynaphthalene, catechol, and L-3,4-dihydroxyphenylalanine

1978 ◽  
Vol 24 (3) ◽  
pp. 289-297 ◽  
Author(s):  
M. H. Wheeler ◽  
W. J. Tolmsoff ◽  
A. A. Bell ◽  
H. H. Mollenhauer
Keyword(s):  
Verticillium Dahliae ◽  
Wild Type ◽  
Melanin Biosynthesis

Microsclerotia of three melanin-deficient mutants of Verticillium dahliae formed melanin from (+)-scytalone, 1,8-dihydroxynaphthalene, catechol, and L-3.4-dihydroxyphenylalanine. The melanins formed from (+)-scytalone or 1,8-dihydroxynaphthalene resembled wild-type melanin chemically and ultrastructurally, whereas the melanins formed from catechol and L-3,4-dihydroxyphenylalanine were different. This suggests that scytalone and 1,8-dihydroxynaphthalene but not catechol or L-3,4-dihydroxyphenylalanine are natural intermediates of melanin biosynthesis in V. dahliae.

Influence of double-stranded RNAs on growth, sporulation, pathogenicity, and survival of Chalara elegans

1995 ◽  
Vol 73 (7) ◽  
pp. 1001-1009 ◽  
Author(s):  
Zamir K. Punja
Keyword(s):  
Plant Pathogen ◽  
Dry Weight ◽  
Complete Loss ◽  
Thielaviopsis Basicola ◽  
Wild Type ◽  
C Elegans ◽  
Chalara Elegans ◽  
In The Wild ◽  
Rna Fragments ◽  
Type Strains

Three strains of Chalara elegans from diverse geographical areas that contained multiple (4 or 5) double-stranded RNA fragments were compared with spontaneously derived cultures from these strains that were either partially cured or completely free of dsRNA. In the wild-type strains, presence of the dsRNAs was found to significantly enhance phialospore production and pigmentation of colonies, whereas radial growth and mycelial dry weight accumulation were reduced. The rate and overall percentage of phialospore germination on 1% Noble water agar were also significantly reduced by the presence of the dsRNAs. In two partially cured strains (only one 2.8-kb fragment remaining), pathogenicity to various plant tissues was significantly enhanced when compared with the wild-type strains containing multiple dsRNA. However, survival in field soil was enhanced in one strain and reduced in the other. In the completely cured strain, the loss of multiple dsRNA fragments was associated with enhanced growth, reduced phialospore production, and a complete loss of pathogenicity and capability for survival in soil. These results indicate that the effects of dsRNAs in C. elegans vary with the strain. In general, the presence of multiple dsRNAs in this fungus enhanced sporulation, altered colony morphology, and reduced growth and pathogenicity. However, since the complete loss of dsRNA was found to eliminate pathogenicity and reduce survival, it suggests that some dsRNA fragments in C. elegans may confer an advantage to this soil-borne facultative plant pathogen. Key words: black root rot, soil-borne plant pathogen, Thielaviopsis basicola.

scholarly journals Studies on the Scutellar Bristles of Drosophila melanogaster. IV. Selection for Low Bristle Number in Oregon-RC Wild-type Lines

1984 ◽  
Vol 37 (4) ◽  
pp. 277
Author(s):  
BL Sheldon ◽  
M K Evans
Keyword(s):  
Recessive Gene ◽  
Population Level ◽  
Initial Response ◽  
The Other ◽  
Selection Line ◽  
Base Population ◽  
Wild Type ◽  
Threshold Phenomenon ◽  
Bristle Number ◽  
Selection For

Results are presented of 130-145 generations of selection for low scutellar bristle number in four lines of D. melanogaster derived directly from an Oregon-RC wild-type stock and in one derived from an Oregon-RC line selected for low sternital bristle number. The most rapid initial response and the lowest mean scutellar bristle number ultimately reached, just below 2 bristles, occurred in a line in which the response was due to a new recessive gene located at approximately 17�4 on the X chromosome. Three of the other four lines reached a plateau just above a mean of 2 bristles after different patterns of response. These plateaux reflected a new canalization or threshold phenomenon at 2 bristles in these lines. The remaining line reached a mean of about 2� 5 bristles after some 50 generations and remained at that level or slightly higher thereafter, but had no indication of canalization at 2 bristles. Two relaxed lines were derived from each selection line at different times and showed variable patterns of regression towards the base population level.

scholarly journals A buff spore colour mutant in Sordaria brevicollis showing high-frequency conversion: 2. Loss of the high-frequency conversion

1983 ◽  
Vol 41 (2) ◽  
pp. 155-163 ◽  
Author(s):  
Mary V. Macdonald ◽  
Harold L. K. Whitehouse
Keyword(s):  
Nucleotide Sequence ◽  
High Frequency ◽  
Frequency Conversion ◽  
Recessive Gene ◽  
Initiation Site ◽  
Dominant Allele ◽  
Single Recessive Gene ◽  
Wild Type ◽  
Colour Mutant ◽  
Conversion Frequency

SUMMARYA mutant, YS17, at the buff spore colour locus in Sordaria brevicollis has previously been described. It shows conversion with high frequency, predominantly to wild type, and is believed to act as a recognition site for an endonuclease that initiates recombination at the YS17 site. The discovery is now reported of a gene that causes loss of the high-frequency conversion shown by the YS17 mutant. The gene was present in existing stocks of the fungus. It reduces the conversion frequency of YS17 to a level similar to that of other buff mutants, from which it is inferred that the YS17 mutant no longer acts as an initiation site for recombination. When the conversion frequency of YS17 is low the bias in conversion to wild type rather than to mutant is lost, suggesting that this bias may relate to the initiation of recombination at the site. The loss of high frequency conversion of YS17 appears to be determined by a single recessive gene linked to mating type and unlinked to buff. It is suggested that the dominant allele induces recombination at the site of YS17 by controlling either the synthesis or the activity of an endonuclease that is capable of recognising the nucleotide sequence at the YS17 site. Some anomalous results point to the existence of modifiers of the action of the gene.

Developmentally related changes in the production and expression of endo-β-1,4-glucanases in Aspergillus nidulans

Genome ◽  
1989 ◽  
Vol 32 (2) ◽  
pp. 288-292 ◽  
Author(s):  
P. S. Bagga ◽  
S. Sharma ◽  
D. K. Sandhu
Keyword(s):  
Aspergillus Nidulans ◽  
The Other ◽  
Wild Type ◽  
Stages Of Development ◽  
Experimental Conditions ◽  
The Third ◽  
Developmental Mutants ◽  
Mutant Strains ◽  
In The Wild ◽  
Low Levels

The production and electrophoretic expression of endoglucanase(s) were compared in the wild-type and three developmental mutants of Aspergillus nidulans. In the wild type, the production of endoglucanase and its distribution in extracellular and intracellular fractions varied with the age of the culture and the yield was better in stable cultures (production of conidia and cleistothecia) as compared with shake cultures (vegetative hyphae only). Two developmental mutants, aco-T69 and aco-40, which lack the development of conidia and cleistothecia, produced low levels of endoglucanase enzymes as compared with the wild type grown under similar conditions. On the other hand, in aco-90, a mutant capable of producing cleistothecia but no conidia, endoglucanase production was better. The results indicate a correlation between cleistothecial development and endoglucanase level. The electrophoretic studies revealed the presence of three forms of endoglucanase, i.e., EGI, EGII, and EGIII. The first two were detectable in the wild type as well as in mutant strains when grown under various experimental conditions and at all the stages of development. However, the third form could be observed only during cleistothecial development, indicating that this isozyme is developmentally regulated.Key words: endoglucanases, development, Aspergillus nidulans.

SINGLE GENE CONTROL OF SEED COLOR AND HYPOCOTYL COLOR IN TURNIP RAPE

1982 ◽  
Vol 62 (2) ◽  
pp. 331-334 ◽  
Author(s):  
J. A. HAWK
Keyword(s):  
Brassica Campestris ◽  
Single Gene ◽  
Recessive Gene ◽  
Early Flowering ◽  
Pigment Production ◽  
Gene Control ◽  
Seed Color ◽  
Single Recessive Gene ◽  
Wild Type ◽  
Turnip Rape

The association between hypocotyl color and seed color in turnip rape (Brassica campestris L.) was investigated in crosses of a green hypocotyl, yellow-seeded stock with an early flowering wild-type stock and the Torch cultivar. A complete association was noted between seed color and hypocotyl color. These data are consistent with the hypothesis that a single recessive gene may block pigment production in both hypocotyl and seed. The relevance of this information for breeding yellow-seeded turnip rape cultivars is discussed.

scholarly journals Ester-Producing Mechanism of Ethanol O-acyltransferaseEHT1Gene inPichia pastorisfrom Shanxi Aged Vinegar

2019 ◽  
Vol 2019 ◽  
pp. 1-9
Author(s):  
Jia Chen ◽  
Ruipeng Nan ◽  
Rufu Wang ◽  
Lixin Zhang ◽  
Junfeng Shi
Keyword(s):  
Fatty Acids ◽  
Esterase Activity ◽  
Volatile Fatty Acids ◽  
The Other ◽  
Fatty Acid Esters ◽  
Wild Type ◽  
Fermentation Products ◽  
Over Expression ◽  
In The Wild ◽  
Methyl Nonanoate

The ethanol O-acyltransferaseEHT1is an important element of key signaling pathways and is widely expressed in yeast strains. In this study, we investigated the expression ofEHT1 in the overexpression lines or knockout system ofPichia pastorisusing qRT-PCR and western blotting. The amount of total protein was determined using the Bradford method; the esterase activity was determined using p-nitrophenyl acetate as a substrate, and the production of volatile fatty acids in wild-type, knockout, and over-expression systems was detected using SPME GC-MS. The esterase activity ofEHT1-knockoutP. pastoriswas significantly lower than that in wild type (P<0.01), and the activities of esterase in threeEHT1-overexpressing strains—OE-1, OE-2, and OE-3—were significantly higher than those in wild type (P<0.01). In theEHT1-knockout strain products, the contents of nine volatile fatty acids were significantly lower than those in wild type (P<0.01), and the relative percentages of three fatty acids, methyl nonanoate, methyl decanoate, and ethyl caprate, were significantly lower than those in the other six species in the wild-type and knockout groups (P<0.05). The nine volatile fatty acids in the fermentation products of the overexpressedEHT1 gene were significantly higher than those in the wild-type group (P<0.01). The relative percentages of the three fatty acid esters, methyl nonanoate, methyl caprate, and ethyl caprate, were significantly higher than those in the other six species (P<0.05).EHT1 plays an important regulatory role in esterase activity and the production of medium-chain volatile fatty acids.

scholarly journals Biosynthesis and Functions of Melanin inSporothrix schenckii

2000 ◽  
Vol 68 (6) ◽  
pp. 3696-3703 ◽  
Author(s):  
Rafael Romero-Martinez ◽  
Michael Wheeler ◽  
Antonieta Guerrero-Plata ◽  
Guadalupe Rico ◽  
Haydée Torres-Guerrero
Keyword(s):  
High Performance ◽  
Uv Light ◽  
Sporothrix Schenckii ◽  
Uv Spectra ◽  
Wild Type ◽  
Melanin Biosynthesis ◽  
Worldwide Distribution ◽  
Mutant Strains ◽  
In The Wild ◽  
Cutaneous Mycosis

ABSTRACT Sporothrix schenckii is a human pathogen that causes sporotrichosis, an important cutaneous mycosis with a worldwide distribution. It produces dark-brown conidia, which infect the host. We found that S. schenckii synthesizes melanin via the 1,8-dihydroxynaphthalene pentaketide pathway. Melanin biosynthesis in the wild type was inhibited by tricyclazole, and colonies of the fungus were reddish brown instead of black on tricyclazole-amended medium. Two melanin-deficient mutant strains were analyzed in this study: an albino that produced normal-appearing melanin on scytalone-amended medium and a reddish brown mutant that accumulated and extruded melanin metabolites into its medium. Scytalone and flaviolin obtained from cultures of the reddish brown mutant were identified by thin-layer chromatography, high-performance liquid chromatography, and UV spectra. Transmission electron microscopy showed an electron-dense granular material believed to be melanin in wild-type conidial cell walls, and this was absent in conidial walls of the albino mutant unless the albino was grown on a scytalone-amended medium. Melanized cells of wild-type S. schenckii and the albino grown on scytalone-amended medium were less susceptible to killing by chemically generated oxygen- and nitrogen-derived radicals and by UV light than were conidia of the mutant strains. Melanized conidia of the wild type and the scytalone-treated albino were also more resistant to phagocytosis and killing by human monocytes and murine macrophages than were unmelanized conidia of the two mutants. These results demonstrate that melanin protects S. schenckii against certain oxidative antimicrobial compounds and against attack by macrophages.

Ultrastructure of melanin formation in Verticillium dahliae with (+)-scytalone as a biosynthetic intermediate

1976 ◽  
Vol 22 (5) ◽  
pp. 702-711 ◽  
Author(s):  
M. H. Wheeler ◽  
W. J. Tolmsoff ◽  
S. Meola
Keyword(s):  
Verticillium Dahliae ◽  
Cell Walls ◽  
Maximum Rate ◽  
Melanin Synthesis ◽  
Wild Type ◽  
Type Isolate ◽  
Albino Mutant ◽  
In The Wild ◽  
Fibrillar Network ◽  
Scanning Electron

Transmission and scanning electron microscopy showed that melanin of wild-type Verticillium dahliae occurred as granules in microsclerotial cell walls and in a fibrillar network encapsulating the walls. An albino microsclerotial mutant and a brown microsclerotial mutant of V. dahliae did not form melanin granules. When albino microsclerotia were treated with (+)-scytalone (a metabolite that the brown mutant accumulates), they formed melanin granules and turned black. These granules were similar in appearance and distribution to those in the wild type. Melanin granules of the wild-type isolate and the scytalone-treated albino mutant were formed at a maximum rate in microsclerotia from 5- to 8-day-old cultures. These observations suggest that scytalone is a natural intermediate of melanin synthesis in V. dahliae.

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