Academic literature on the topic 'Nigrospora oryzae'

Nigrospora oryzae bas competitive properties in relation to the fungi of the genus <i>Fusarium: F. avenaceum, F. culmorum</i> and <i>Rhizoctonia cerealls</i>, pathogenical for rye. In favourable conditions of Wrocław surroundings <i>Nigrospora oryzae</i> passes over from ycar to year on the seeds. Due to this property <i>Nigrospora oryzae</i> can constitute a protective covering for rye against ihe parasitical fungi of the genus <i>Fusarium</i>, provided that a contact with the rye roots will be established respectively earlier.

During 2000 and 2001, a lint rot of cotton bolls (Gossypium hirsutum L.) was reported in the coastal region of Alabama when precipitation was 55% lower than the 5-year average. Bolls at an early stage of opening contained gray mycelium within the locules. At maturity, the lint within the infected locules was discolored, and the fibers were compact resulting in the characteristic “gray lock” sign and symptom attributed to Nigrospora oryzae (Berk. & Broome) Petch. Roots, petioles, leaves, and bolls when present were sampled at the seedling, first bloom, full bloom, and maturity stages of cotton development. A total of 640 sections of tissue (approximately 5 mm2) were surface sterilized for 20 s in 95% ethanol followed by 60 s in 0.525% NaOCl and aseptically plated on potato dextrose agar. Plates were incubated in the dark at 25°C for 3 to 10 days. N. oryzae was isolated at low frequencies from all plant tissues beginning at first bloom. Developing bolls at full bloom were colonized at a frequency of 48%. N. oryzae conidiophores were branched, flexuous, and pallid to brown with smooth walls 4 to 7 (5) μm thick. Conidiogenous cells were monoblastic, single, and 6 to 9 (7.5) μm in diameter. Conidia were single, smooth, broadly ellipsoidal, dark brown to black, single-celled, and 11 to 16 (14) μm in diameter (2). Principal component analysis was used to examine the relationship between disease incidence and weather parameters. Weather data was obtained from Auburn University Mesonet located in fields where the samples were collected. Principal components from weather data were ambient and soil maximum, minimum, and average temperature, maximum, minimum, and average relative humidity and precipitation. The first principal component, which is temperature, accounted for 61% of total joint variation among original observations. The second principal component, which was related to the moisture variables, accounted for 19% of the variation. The abundance of N. oryzae was correlated with the principal component factor moisture (r = -0.78**). The dry conditions experienced in this region were conducive to N. oryzae lint rot of cotton. This disease has been reported on cotton primarily in arid climates typical of the southwestern United States (1). To our knowledge, this is the first report of N. oryzae lint rot in the southeastern United States. References: (1) W. E. Batson. Boll rots. Pages 36–38 in: Compendium of Cotton Diseases. T. L. Kirkpatrick and C. S. Rothrock, eds. The American Phytopathological Society, St. Paul, MN. 2001. (2) M. B. Ellis. Dematiaceous Hyphomycetes, CAB, Kew, Surrey, England, 1971.

Three dsRNAs, in sizes of approximately 2.5–5 kbp, were detected in the plant pathogenic fungus Nigrospora oryzae strain CS-7.5-4. Genomic analysis showed that the 5.0 kb dsRNA was a victorivirus named as Nigrospora oryzae victorivirus 2 (NoRV2). The genome of NoRV2 was 5166 bp in length containing two overlapping open reading frames (ORFs), ORF1 and ORF2. ORF1 was deduced to encode a coat protein (CP) showing homology to the CPs of viruses belonging to the Totiviridae family. The stop codon of ORF1 and the start codon of ORF2 were overlapped by the tetranucleotide sequence AUGA. ORF2 was predicted to encode an RNA-dependent RNA polymerase (RdRp), which was highly similar to the RdRps of victoriviruses. Virus-like particle examination demonstrated that the genome of NoRV2 was solely encapsidated by viral particles with a diameter of approximately 35 nm. The other two dsRNAs that were less than 3.0 kb were predicted to be the genomes of two mitoviruses, named as Nigrospora oryzae mitovirus 1 (NoMV1) and Nigrospora oryzae mitovirus 2 (NoMV2). Both NoMV1 and NoMV2 were A-U rich and with lengths of 2865 and 2507 bp, respectively. Mitochondrial codon usage inferred that each of the two mitoviruses contains a major large ORF encoding a mitoviral RdRp. Horizontal transfer experiments showed that the NoMV1 and NoMV2 could be cotransmitted horizontally via hyphal contact to other virus-free N. oryzae strains and causes phenotypic change to the recipient, such as an increase in growth rate. This is the first report of mitoviruses in N. oryzae.

Abstract Calibrachoa hybrida (calibrachoa, million bells) is a flowering ornamental with increasing importance due to the existence of many successful cultivars for growing indoors in containers and planting in the garden and landscape. The outstanding characteristic is a profuse flowering and intense colour. In October 2019, a fungal isolate was obtained from basal calibrachoa leaves with irregular brown leaf spots, in plants cultivated in Buenos Aires, Argentina. The aim of the present study was to identify the cause of the disease in this ornamental genus, to expand knowledge about prevalent pathologies. The isolate was identified using morphological and molecular markers, and the pathogenicity tests were fulfilled. This paper reports that Nigrospora oryzae is pathogenic to calibrachoa, which seems to be the first record of this leaf spot disease in the world.

In this study, the co-culture of Nigrospora oryzae and Beauveria bassiana, the endophytes in the seeds of Dendrobium officinale, were examined for metabolite diversity. Five new azaphilones were isolated, and their structures were determined by spectral analysis. In terms of azaphilones, compound 2 had an unprecedented skeleton, with a bicyclic oxygen bridge. The antifungal selectivities of the metabolite produced by N. oryzae against its co-culture fungus, B. bassiana, and common pathogens exhibited competitive interaction in this mix-culture. Compounds 1 and 2 showed obvious nitric oxide (NO) inhibitory activity with ratios of 37%, and 39%, respectively, at a concentration of 50 μM.

A fungus was isolated consistently from dead shoot tips and flag leaves of Arundo donax L. (Poaceae) in France, Crete, Cyprus, Italy, Morocco, and Spain from April of 2003 through September of 2005. The fungus was identified as Nigrospora oryzae (Berk. & Br.) Petch (teleomorph Khuskia oryzae) on the basis of morphological characteristics (1). The mean diameter of 80 conidia obtained from sporulating plant specimens collected in France, Crete, and Cyprus were 14, 15, and 15 μm, respectively. The mean diameters of 25 conidiogenous cells and conidiophores were 7 and 4 μm, respectively. Identification was confirmed by comparing the sequence of the ribosomal DNA internal transcribed spacer 1 and 4 regions from the French isolate (GenBank Accession No. DQ219433) with the sequence of a voucher specimen from the Museum National d'Histoire Naturelle, Paris, France. The isolate of N. oryzae from France was deposited at the CBS collection in Utrecht, the Netherlands (CBS 113884). N. oryzae is known to be a weak pathogen on a wide range of plants but has not been reported on A. donax, which is now a well-established weed in the United States and North America, probably originating from the Mediterranean Region. Herein, the possible use of N. oryzae as a biological control agent was investigated. Twenty young A. donax shoots growing in the greenhouse and 20 emerging canes in the field were selected on the basis of uniformity in size. A spore suspension in distilled water adjusted to 5 × 105 conidia/ml of the French isolate was prepared and 0.5 ml was injected with a syringe just below the growing point of the flag leaf in onehalf of the greenhouse and field plants. The remaining plants were injected with 0.5 ml of distilled water as controls. Infection and death of the flag leaf occurred in 30% of the shoots in the greenhouse and 50% of the canes in the field 21 days from inoculation. No disease developed on the control plants. Greenhouse inoculation tests were repeated once. N. oryzae was reisolated from dead leaves and the terminal node of inoculated shoots, satisfying Koch's postulate. Attempts made to induce disease symptoms by applying spore suspensions on the whorl of leaves surrounding the apical tip failed. This is an indication that an insect vector may be needed to carry and deposit N. oryzae spores into the tight, whorled flag leaf for infection and disease development to occur. To our knowledge, this is the first report of foliar and cane rot of A. donax caused by N. oryzae. References: (1) K. H. Domsch et al. Page 515 in: Compendium of Soil Fungi. IHW-Verlag, Eching, Germany, 1993.

Serrated tussock (Nassella trichotoma) and Giant Parramatta Grass (Sporobolus fertilis) are among the most noxious weeds in Australia. Both cause problems in pasture and there are limited control measures relying heavily on the herbicide flupropanate. With the recent confirmation of flupropanate resistance in serrated tussock and the report of suspected flupropanate resistance in Giant Parramatta Grass (GPG), this option appeared to be under threat.The aims of this thesis were to determine the extent of flupropanate resistance in serrated tussock and GPG in Australia and to understand the genetics of flupropanate resistance in serrated tussock. This thesis also documents the GPG resistance to 2,2-DPA and investigates a fungal pathogen, Nigrospora oryzae, as a potential biocontrol agent for GPG. A local paddock survey determined the spread and extent of flupropanate resistance in serrated tussock within 5 km of the original resistant site. The pot-dose method of assessing resistance identified plants resistant to flupropanate up to 3.5 km from the original site found in Victoria. Seeds from these plants showed 0-100% resistance, with sensitive plants often having a low („T5%) level of resistant seed. These results indicate the movement of flupropanate resistance through seeds or pollen and shows that its spread occurred within one year of detection. A national mail survey confirmed the massive impacts of serrated tussock across Australia, with annual serrated tussock costs ranging from $15,000 to $16,000 per year per respondent. This survey also identified the widespread infestation of this weed in a variety of land use patterns, from pasture to native grasslands, and the decrease in the value of farmland as a result. Heritability studies using controlled breeding experiments indicated a strong involvement of a maternal component in the inheritance of flupropanate resistance in serrated tussock, with a minor proportion of resistance heritable through pollen. GPG plants and seedlings were tested for flupropanate and 2,2-DPA resistance.Seedlings tested for flupropanate resistance were highly resistant (tolerating 33-39 times more than sensitive biotypes). With 2,2-DPA, resistant GPG plants did not die even at 14 times the field rate and resistant seedlings also showed 5-6 times more resistance than the sensitive biotype. The study has confirmed that flupropanate and 2,2-DPA resistance now exists in GPG.The potential of Nigrospora oryzae, a pathogenic fungus, as a biocontrol agent for GPG was determined. Mature plants and seedlings of GPG were inoculated with conidia of N. oryzae using three treatments (run-off, crown, and spray). Inoculated plants were smaller, with greater proportions of dead leaves (70% with the run-off a nd crown treatments and 53% with the spray treatment) than the control plants. GPG seedlings inoculated with N. oryzae were stunted and showed greater proportions of necrotic leaves in all the treatments than the control. There is potential to develop N. oryzae as a mycoherbicide to control GPG and further testing is warranted.