Chlorate toxicity in Aspergillus nidulans: The selection and characterisation of chlorate resistant mutants

Cove, David J.

doi:10.1038/hdy.1976.24

Cited by 205 publications

(119 citation statements)

References 11 publications

(11 reference statements)

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“…In several systems ranging from microbes to higher plants, Cl03-has been used to isolate mutants deficient in N03-reduction and, in a limited number of cases, deficient in N03-uptake (8,20,28,29 …”

Section: Transportmentioning

confidence: 99%

See 1 more Smart Citation

Effects of Nitrite, Chlorate, and Chlorite on Nitrate Uptake and Nitrate Reductase Activity

Siddiqi¹,

King²,

Glass³

1992

Plant Physiol.

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Effects of N02-, C103-, and C102-on the induction of nitrate transport and nitrate reductase activity (NRA) as well as their effects on N03-influx into roots of intact barley (Hordeum vulgare cv Klondike) seedlings were investigated. A 24-h pretreatment with 0.1 mol m-3 N02-fully induced N03-transport but failed to induce NRA. Similar pretreatments with C103-and C102-induced neither N03-transport nor NRA. Net C103-uptake was induced by N03-but not by C103-itself, indicating that N03-and C103-transport occur via the N03-carrier. At the uptake step, N02-and C102-strongly inhibited N03-influx; the former exhibited classical competitive kinetics, whereas the latter exhibited complex mixed-type kinetics. C103-proved to be a weak inhibitor of N03-influx (Ki = 16 mol m-3) in a noncompetitive manner. The implications of these findings are discussed in the context of the suitability of these N03-analogs as screening agents for the isolation of mutants defective in N03-transport.Most high-affinity solute transport systems in plants appear to be derepressible; when their solutes are withheld, transport rates increase severalfold (14,22). Ion transport systems involved in the absorption of Cl-, S04, H2PO4-, K+, Na+ (see ref. 14 for review), and NH4' (34) conform to this this pattern.The HATS2 for N03-absorption is, therefore, exceptional in being substrate inducible as well as subject to negative feedback (6,24,31). Enzymes involved in nitrate assimilation, NR and NiR, are also substrate inducible.The absence of a readily available radiotracer for N03-has led to the widespread use of C103-as a N03-analog in studies of N03-uptake and assimilation in both plants and microorganisms (10). 36C03-, which can be generated by electrolysis of 36Cl-, has provided a useful tracer for N03-. However, at high concentrations (0.5 mol m-3 and above) and during prolonged exposures, C103-has proven to be toxic to most plants. Indeed, C103-was previously used extensively as a herbicide (16 In Vivo NRA In vivo NRA in roots was assayed by measuring NO2-production under anaerobic conditions (12). Briefly, excised roots were incubated in potassium phosphate buffer (pH 7.7) containing 100 mol m-3 NO3-, maintained at 250C for 20 min. Before the transfer of roots to anaerobic conditions, the buffer was purged with He for 5 min. At the end of the incubation period, the tubes were transferred to a boiling water bath for 10 min to extract NO2-from the roots. NO2 content was measured spectrophotometrically: the color re-

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Section: Transportmentioning

confidence: 99%

“…Rather, genotypes defective in NRA are isolated, supporting the contention that C102-rather than C103-is the effective toxin. Notwithstanding these observations, Cove (8) demonstrated that in Aspergillus the toxic effects of C103-were not necessarily related to the extent of induction of NR.…”

mentioning

confidence: 97%

Effects of Nitrite, Chlorate, and Chlorite on Nitrate Uptake and Nitrate Reductase Activity

Siddiqi¹,

King²,

Glass³

1992

Plant Physiol.

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“…Some fungi, such as Basidiomycetes, Saprolegniaceae and Blastocladiales, are unable to utilise nitrate and cannot synthesise nitrate reductase (Correll et al, 1987). Cove (1976) has discovered that mutants not resistant to chlorate (KClO 3 ) are also nit mutants. Chlorate, a nitrate analogue, has been used for studying hetorokaryosis in Fusarium and nitrate assimilation in fungi, bacteria, algae and plants.…”

Section: Auxotrophic Mutantsmentioning

confidence: 99%

The use of vegetative compatibility tests for identification of biodiversity of phytopathogenic fungi

et al. 2013

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SUMMARYVisual assessment of phenotypes, performed when two strains of one fungal species are cultivated in a mixed culture on specific media, is known as vegetative or heterokaryotic compatibility or incompatibility test, which enables identification of fungal clones and their classification based on phylogenetic groups. Hyphae of strains that have identical alleles at all vic loci can anastomose into a form of a visible heterokaryon. Strains that divide compatible loci and can anastomose each other belong to a subpopulation termed the vegetative compatibility group (VCG), which is genetically distinguishable from other VCGs. Each VCG is specific regarding its host plant or related host groups and can, but does not have to be virulent on other hosts.Vegetative compatibility can be established in different ways, but complementary auxotrophic strains or strains formed by spontaneous mutation during nutrition, capable of forming a prototrophic heterokaryon are predominantly used. The nit mutants are considered excellent genetic markers for determination of vegetative compatibility and grouping of strains or clones of one fungus into the same or different VCGs. The ability only to determine whether strains are the same or not, but not the degree of their relatedness using VCG, is a limiting factor in analyses that could be performed. VCGs are the most efficient when they are employed to detect the presence of a specific strain in a population.This paper provides an overview of the importance of the phenomenon of vegetative compatibility. Vegetative compatibility is one of the most important genetic traits in ascomycetes by which one subpopulation can be identified as a distinct genetic group. Furthermore, the procedures for isolation, identification and determination of nit mutant phenotypes, and for identification of complementary strains and VCGs are described in detail.

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“…Nitrate reductase, the first enzyme in nitrate utilization, also catalyzes the reduction of chlorate to chlorite, which is toxic (Cove, 1976a(Cove, . 1976b.…”

Section: How To Identify Mutantsmentioning

confidence: 99%

Mutant analysis, a key tool for the study of metabolism and development

Cove

1993

The Plant Journal

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Chlorate toxicity in Aspergillus nidulans: The selection and characterisation of chlorate resistant mutants

Cited by 205 publications

References 11 publications

Effects of Nitrite, Chlorate, and Chlorite on Nitrate Uptake and Nitrate Reductase Activity

Effects of Nitrite, Chlorate, and Chlorite on Nitrate Uptake and Nitrate Reductase Activity

The use of vegetative compatibility tests for identification of biodiversity of phytopathogenic fungi

Mutant analysis, a key tool for the study of metabolism and development

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