~ A small family of necrosis-inducing peptides has been identified as virulence factors of Rhynchosporium secalis, a fungal pathogen of barley (Hordeum vulgare 1.) Two members of this family, NlPl and NIP3, were found to stimulate the... more
~ A small family of necrosis-inducing peptides has been identified as virulence factors of Rhynchosporium secalis, a fungal pathogen of barley (Hordeum vulgare 1.) Two members of this family, NlPl and NIP3, were found to stimulate the phosphohydrolyzing activity of the Mg'+-dependent, K+-stimulated H+-ATPase of plasma mem- brane vesicles isolated from barley leaves by partitioning in an aqueous two-phase system. Stimulation of enzyme activity was saturated by 10 to 15 PM fungal protein. Another member of the peptide family, NIPZ, did not affect the enzyme, indicating that it has a different mode of action. Leaf scald of barley (Hordeum vulgare L.) is caused by the imperfect fungus Rhynchosporium secalis (Oudem.) J.J. Davis. The pathogen grows subcuticularly, primarily above anti- clinal epidermal walls during early stages of pathogenesis. Only at late stages of development could fungal hyphae be found in the leaf mesophyll (Ayesu-Offei and Clare, 1970; Lehnackers and Knogge, 19...
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Rhynchosporium commune is a haploid fungus causing scald or leaf blotch on barley, other Hordeum spp. and Bromus diandrus. Rhynchosporium commune is an anamorphic Ascomycete closely related to the teleomorph Helotiales genera Oculimacula... more
Rhynchosporium commune is a haploid fungus causing scald or leaf blotch on barley, other Hordeum spp. and Bromus diandrus. Rhynchosporium commune is an anamorphic Ascomycete closely related to the teleomorph Helotiales genera Oculimacula and Pyrenopeziza. Rhynchosporium commune causes scald-like lesions on leaves, leaf sheaths and ears. Early symptoms are generally pale grey oval lesions. With time, the lesions acquire a dark brown margin with the centre of the lesion remaining pale green or pale brown. Lesions often merge to form large areas around which leaf yellowing is common. Infection frequently occurs in the leaf axil, which can lead to chlorosis and eventual death of the leaf. LIFE CYCLE: Rhynchosporium commune is seed borne, but the importance of this phase of the disease is not fully understood. Debris from previous crops and volunteers, infected from the stubble from previous crops, are considered to be the most important sources of the disease. Autumn-sown crops can become infected very soon after sowing. Secondary spread of disease occurs mainly through splash dispersal of conidia from infected leaves. Rainfall at the stem extension growth stage is the major environmental factor in epidemic development. DETECTION AND QUANTIFICATION: Rhynchosporium commune produces unique beak-shaped, one-septate spores both on leaves and in culture. The development of a specific polymerase chain reaction (PCR) and, more recently, quantitative PCR (qPCR) has allowed the identification of asymptomatic infection in seeds and during the growing season. The main measure for the control of R. commune is the use of fungicides with different modes of action, in combination with the use of resistant cultivars. However, this is constantly under review because of the ability of the pathogen to adapt to host plant resistance and to develop fungicide resistance.
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... et al., 1988) and rice, whereas a 1,3-1,6-branched tetra-glucan from cell walls of the rice pathogen Magnaporthe grisea is active in rice, but not in soybean (Yamaguchi et al ... From information gained by the analysis of cloned plant... more
... et al., 1988) and rice, whereas a 1,3-1,6-branched tetra-glucan from cell walls of the rice pathogen Magnaporthe grisea is active in rice, but not in soybean (Yamaguchi et al ... From information gained by the analysis of cloned plant R and pathogen Avr genes, however, a ...
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This report describes the separation of components from a 4-coumarate:CoA ligase assay by means of liquid chromatography. With the aid of polyamide column chromatography it is possible to enrich and isolate chromatographically and UV... more
This report describes the separation of components from a 4-coumarate:CoA ligase assay by means of liquid chromatography. With the aid of polyamide column chromatography it is possible to enrich and isolate chromatographically and UV spectroscopically pure p-coumaroyl-CoA using as a solvent 0.01% NH4OH in methanol subsequent to water and methanol alone. High performance liquid chromatography on octadecylsilane-bonded silica stationary phase allows a discontinuous determination of ligase activity. All components - ATP, Coenzyme A, p-coumaric acid, and the products AMP and p-coumaroyl-CoA - can be separated and accurately quantified within 20 min using a water-acetonitrile gradient, containing 1% phosphoric acid. The presented HPLC method may be used to affirm the accuracy of optical tests.
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A small family of necrosis-inducing peptides has been identified as virulence factors of Rhynchosporium secalis, a fungal pathogen of barley (Hordeum vulgare L.) Two members of this family, NIP1 and NIP3, were found to stimulate the... more
A small family of necrosis-inducing peptides has been identified as virulence factors of Rhynchosporium secalis, a fungal pathogen of barley (Hordeum vulgare L.) Two members of this family, NIP1 and NIP3, were found to stimulate the phosphohydrolyzing activity of the Mg2+-dependent, K+-stimulated H+-ATPase of plasma membrane vesicles isolated from barley leaves by partitioning in an aqueous two-phase system. Stimulation of enzyme activity was saturated by 10 to 15 [mu]M fungal protein. Another member of the peptide family, NIP2, did not affect the enzyme, indicating that it has a different mode of action.
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Seven races of Rhynchosporium secalis were screened for their virulence on a variety of barley cultivars. Four races were identified as virulent on cultivar Atlas 46 (resistance loci Rrs1 and Rrs2) but virulent on the near-isogenic... more
Seven races of Rhynchosporium secalis were screened for their virulence on a variety of barley cultivars. Four races were identified as virulent on cultivar Atlas 46 (resistance loci Rrs1 and Rrs2) but virulent on the near-isogenic cultivar Atlas (Rrs2). For one of these races, US238.1, the fungal infection cycle was followed on the susceptible cultivar by means of light and scanning electron microscopy. From a comparative analysis of fungal development on the susceptible and resistant cultivars, two lines of plant defense emerged: (i) inhibition of spore germination on the leaf surface and (ii) prevention of the establishment of the subcuticular stroma. Investigations of the development of race US238.1 on different barley cultivars with and without Rrs1 and on F1 individuals from different crosses excluded involvement of Rrs1 in the inhibition of spore germination. Possible pathogenicity mechanisms are discussed. Key words: leaf scald, microscopy, plant resistance.
Book of Abstracts of Invited Papers 8th International Congress of Plant Pathology, Christchurch, New Zealand, 2-7 February 2003
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Scald caused by Rhynchosporium commune is an important foliar disease of barley. Insertion mutagenesis of R. commune generated a nonpathogenic fungal mutant which carries the inserted plasmid in the upstream region of a gene named PFP1.... more
Scald caused by Rhynchosporium commune is an important foliar disease of barley. Insertion mutagenesis of R. commune generated a nonpathogenic fungal mutant which carries the inserted plasmid in the upstream region of a gene named PFP1. The characteristic feature of the gene product is an Epc-N domain. This motif is also found in homologous proteins shown to be components of histone acetyltransferase (HAT) complexes of fungi and animals. Therefore, PFP1 is suggested to be the subunit of a HAT complex in R. commune with an essential role in the epigenetic control of fungal pathogenicity. Targeted PFP1 disruption also yielded nonpathogenic mutants which showed wild-type-like growth ex planta, except for the occurrence of hyphal swellings. Complementation of the deletion mutants with the wild-type gene reestablished pathogenicity and suppressed the hyphal swellings. However, despite wild-type-level PFP1 expression, the complementation mutants did not reach wild-type-level virulence. Th...
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... et al., 1988) and rice, whereas a 1,3-1,6-branched tetra-glucan from cell walls of the rice pathogen Magnaporthe grisea is active in rice, but not in soybean (Yamaguchi et al ... From information gained by the analysis of cloned plant... more
... et al., 1988) and rice, whereas a 1,3-1,6-branched tetra-glucan from cell walls of the rice pathogen Magnaporthe grisea is active in rice, but not in soybean (Yamaguchi et al ... From information gained by the analysis of cloned plant R and pathogen Avr genes, however, a ...