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Ustiloxin D, produced by the rice plant pathogen Ustilaginoidea virens, exhibits potent anti-tubulin activity. In order to elucidate the effects of functional groups in ustiloxin D on its activity, several derivatives were synthesized and their anti-tubulin activities were estimated. The N,N-dimethylamino derivative and the 14-O-methyl derivative were inactive (IC50 > 50 microM). 20-Hydroxymethylated ustiloxin D showed decreased inhibitory activity compared with ustiloxin D.

Ustiloxins A (1a), B (1b), C (1c), D (1d) and E (1e), antimitotic peptides, have been isolated from the water extract of false smut balls caused on the panicles of rice plant by a fungus Ustilaginoidea virens. The structure of 1b was assigned from its spectral property and its amino acid analysis in relation to 1a whose structure was determined previously by a combination of X-ray crystallographic and amino acid analyses. Structures of 1c and 1d were elucidated by their spectroscopic data, specially based on their 1H and 13C NMR spectra. Bioactivities of these compounds against microtubule assembly as well as mammal, plant and fungal cells have been studied.

A crude toxin, obtained by methanol-extraction of a water extract of false smut balls (INA-KOUJI in Japanese) caused by Ustilaginoidea virens on rice panicles, was injected into mice intraperitoneally. Single injection of 100 or 200 mg/kg body weight of the extract was not lethal but caused acute, occasional necrosis of hepatocytes and renal tubular cells, followed by increased number of mitotic figures with occasional multinuclear giant cells. Erosions and ulceration of the forestomach and atrophy of the thymus were observed a week later. Repeated intraperitoneal injection of the crude toxin at the levels of 12 and 25 mg/kg body weight induced more severe necrosis of the liver and kidneys, with delayed occurrence of mitosis. Forestomach erosion also occurred. Serial injection for 10-12 days of either 3 or 6 mg/kg of the crude extract or 400 micrograms/kg of ustiloxin A, using the purified crystals, caused relatively mild but definite liver and kidney lesions similar to those described above. The lesions in the liver and kidney were quite similar to those observed in lupinosis caused by phomopsin A, a mycotoxin produced by Phomopsis leptostromiformis. Isolation of the toxic substance indicates that the contaminated rice panicles may cause toxicosis of cattle, although no field outbreaks have occurred yet.

This article 'False Smut Incidence on Rice Relative to Plant Characters and Environmental Factors' appeared in the International Rice Research Newsletter series, created by the International Rice Research Institute (IRRI). The primary objective of this publication was to expedite communication among scientists concerned with the development of improved technology for rice and for rice based cropping systems. This publication will report what scientists are doing to increase the production of rice in as much as this crop feeds the most densely populated and land scarce nations in the world.

False smut, caused by Ustilaginoidea virens, occurs on rice, corn, and other Gramineae, but is of little economic importance. False or green smut of corn resembles most closely false smut of rice (1). During surveys in 2000 at Mississippi State University, Delta Experiment Station, Stoneville, 32 (2.5%) of 1,280 commercial and inbred corn hybrids had false smut on the tassel. The percentage of plants infected with false smut ranged from 5 to 15% based on a sample of 20 corn plants from a single 4.9-m row plot. Galls (sclerotia), which are similar to ergot, replaced flowers on tassels of infected plants. Disease severity ranged from 2 to 50% infected flowers per inbred. Mature sclerotia were spherical, 6 to 17 mm in diameter, olive green to black, and velvety with white interiors. The fungus could not be isolated on potato dextrose agar. Only the tassels were infected, which resulted in little damage to the plant, except for a decrease in pollen production. Although the disease has been reported to infect other parts of the corn plant, the injury will likely be less on corn than rice. In 2001 and 2002, the disease was not observed. Disease incidence was more prevalent in 2000 because of hot, wet weather immediately after the crop was planted. The observation of the disease in one growing season suggests the pathogen may be common in the Mississippi Delta and the disease may occur under favorable environmental conditions and susceptible corn hybrids. Reference: (1) J. K. Pataky. False smut. Page 35 in: Compendium of Corn Diseases, 3rd ed. D. G. White, ed. American Phytopathological Society, St. Paul, MN, 1999.

The effect of harvesting operations on the incidence of 13 fungal spore types over a rice crop at Bhimavaram (16°32′ N and 81°32′ E), India, was studied. Air samples were obtained over the same field by operating Rotorods for an hour from 0800–0900 h on four occasions before, during and after harvesting. Spore concentrations, especially of Arthrobotrys, Cochliobolus miyabeanus, Drechslera and Ustilaginoidea virens, were greatly elevated on the day of harvesting compared to two days previously, when the crop was still standing. By contrast, spore concentrations of Cercospora were unaffected while Stachybotrys-type declined. Spore concentrations were markedly smaller next day when the harvested crop was left flat in the form of sheaves. A further decrease occurred after the sheaves were removed to leave only the stubbles. It is suggested that repeated exposure of farm workers to unusual heavy spore concentrations during harvesting may be of considerable risk to their health.

稲こうじ病菌の確実な接種法を確立するため,分生胞子の穂ばらみ期注射接種ならびに噴霧接種について検討した。PSA培地で形成させた分生胞子を蒸留水で懸濁し,穂ばらみ期初期ないし中期のイネ葉鞘内に約2ml注入した。接種したイネを2日間低温処理(15C)し,引続き5日間26Cの恒温飽和湿度条件下に静置した後,ガラス室に移すことによって高率に発病させることができた。本菌の感染は低温・飽和湿度で,病徴の発現は高温で促進されるものと推察される。また,分生胞子懸濁液を圃場のイネ体に上から噴霧接種することによっても発病させることができた。接種適期は出穂10∼30日前と思われる。分生胞子を用いた本菌接種法としては初めての報告である。

Circadian periodicities of ten fungal spore types are described in relation to the associated weather using the data obtained with rotorods exposed over a rice crop at Bhimavaram, Andhra Pradesh, India. The periodicity of Leptosphaeria eustomoides conformed to the night pattern, those of Nigrospora, Cladosporium, Trichoconis, Cercospora, Myrothecium and Stachybotrys type to the post‐dawn pattern, of Ustilaginoidea virens to the middle‐day pattern and of Drechslera to the double peak pattern. Some of these differed from those described earlier from elsewhere and the differences are related to variations in weather conditions, and a more detailed study is needed to explain the pattern of spore release in Ustilaginoidea virens.

The two major fungal diseases of rice in Nigeria are rice blast (Pyricularia oryzae Cav.) and brown spot (Cochliobolus miyabeanus (Ito and Kuribayashi) Dreschler ex Dastur). The loss in grain yield attributable to these diseases ranges from 11.5–39.6% and 12–43% respectively, Mancozeb, blasticidin-S, fentin hydroxide, benomyl and edifenphos as foliar sprays effectively control rice blast in the laboratory and field. Brown spot is controlled by spraying with thiram, mancozeb or blasticidin-S. A more useful approach to the control of these diseases being adopted in Nigeria is the search for horizontally resistant varieties. Other fungal diseases of rice in Nigeria are the green smut (Ustilaginoidea virens (Cooke) Tak.), basal sheath rot (Rhizoctonia solani Kuhn), sheath blight (Corticium sasakii (Shirai), Matsumoto.), leaf scald (Rhynchosporium oryzae Hashioka and Yokogi), narrow brown leaf spot (Cercospora oryzae Miyake) and bakanae disease, a foot rot caused by Fusarium moniliforme Sheldon. Two s...

The diurnal and seasonal periodicities in the air-borne spores of Ustilaginoidea virens , the rice false smut fungus, were studied by sampling air at 1 m. above ground level continuously with a Hirst trap located in a rice plot transplanted with Co. 13 seedlings surrounded by plots with Mtu. 19 . The seasonal changes observed in the daily mean concentrations were given, along with information on the growth stages of rice plants in the plot. It was found that the maximum incidence of spores in the air occurs over a period of about 4 weeks which coincides with the ‘heading’ phase of the rice plants, indicating that both early and late infections are possible. On normal dry days the air-borne spores of the fungus exhibited a regular and sharply defined diurnal periodicity with the daily maximum recurring at 22.00 hr. From the 2-hourly changes in the catches during two selected periods it was shown how rainfall affects this diurnal rhythm by reducing the incidence of spores. The highest hourly estimate recorded was c . 328,200/m. 3 of air.

1. The conidia of Cochliobolus miyabeanus and the chlamydospores of Ustilaginoidea virens, and the conidia of Piricularia oryzae lost germinability by compression of 2, 500kg/cm2 and 2, 000kg/cm2, respectively, for 10 minutes. The germ-tubes of C. miyabeanus affected by hydrostatic pressure were slender and shorter than those of the normal. Conidia of C. miyabeanus compressed at 2, 000kg/cm2 for 10 minutes, and those of P. oryzae pressured at 1, 000kg/cm2 for 20-30 minutes, germinated bearing a 3-5-branched germ-tube.2. The germination index of these fungi decreased with the length of time of compression at 1, 000, 1, 500 and 2, 000kg/cm2, except of that of C. miyabeanus which compressed at 1, 000kg/cm2. Tolerance of conidia to the pressure seemed to be largest in C. miyabeanus, though tolerance is variable with spore individuals. The conidia of P. oryzae, however, were found to be lowest in pressure tolerance among the fungi employed, and variation in tolerance due to spore individual was also restricted.3. Elongation of the germ-tubes of the conidia of C. miyabeanus and P. oryzae was restricted in parallel with increase of pressure.

Two polyene macrolide antibiotics: antifungalmycin (1) and fungichromin (2) were isolated from the culture mycelia of Streptomyces padanus 702 via bioactivity-guided fractionation using various chromatographic procedures. Their structures were elucidated on the basis of spectral analysis, and 1 is a new polyene macrolide. Compounds 1 and 2 showed significant inhibition against Gibberella zeae with EC50 values of 26.71 and 2.21 µg/mL, Fusicoccum sp. (plantain head blight) with EC50 values of 23.4 and 3.17 µg/mL, Mucor ssp. 8894 with EC50 values of 28.80 and 2.11 µg/mL, Ustilaginoidea virens with EC50 values of 26.72 and 0.21 µg/mL, respectively. This shows that the microbial secondary metabolites 1 and 2 have the potential to be developed as agricultural fungicides for use against G. zeae, Fusicoccum sp., Mucor ssp. 8894, and U. virens. Electronic Supplementary Material Supplementary material is available for this article at 10.1007/s13659-011-0037-1 and is accessible for authorized users.

Summary Extracts from five West African plants were evaluated in vitro for fungitoxicity against Ustilago maydis, Ustilaginoidea virens, Curvularia lunata and Rhizopus sp. Steam distillate from leaves of Cymbopogon citratus completely inhibited the growth of all four fungi, and hot water extracts from fresh leaves of Ocimum gratissimum and Chromoleana odorata, and dry fruits of Xylopia aethiopica, reduced radial growth by 10–60%. A hot water extract from dry fruits of Monodera myrstica was ineffective as a fungitoxicant.

False smut of rice caused by Ustilaginoidea virens was also found on the grass, Panicum trypheron, a common weed around paddy fields. Cross inoculation studies revealed chlamydospores from P. trypheron infected rice and vice versa. It is concluded P. trypheron is an important source of inoculum between seasons.

This article 'An Alternative Host for Ustilaginoidea virens (Cke.) Tak' appeared in the International Rice Research Newsletter series, created by the International Rice Research Institute (IRRI). The primary objective of this publication was to expedite communication among scientists concerned with the development of improved technology for rice and for rice based cropping systems. This publication will report what scientists are doing to increase the production of rice in as much as this crop feeds the most densely populated and land scarce nations in the world.

This article 'Studies on False-Smut Disease Caused By Ustilaginoidea virens on Paddy in Karnataka, India' appeared in the International Rice Research Newsletter series, created by the International Rice Research Institute (IRRI). The primary objective of this publication was to expedite communication among scientists concerned with the development of improved technology for rice and for rice based cropping systems. This publication will report what scientists are doing to increase the production of rice in as much as this crop feeds the most densely populated and land scarce nations in the world.

The structures of ustilaginoidin B, C28H18O11, m.p. >300°, [α]25D-360°(dioxan) and ustilaginoidin C, C28H18O12, m.p. >300°, [α]25D-260°(dioxan) which were isolated as the pigments of Ustilaginoidea virens (COOKE) TAKAHASHI, were studied mostly by the NMR spectral analyses of their peracetates to conclude as being formulated as II (R=H) and III (R=H), respectively.

A description is provided for Ustilaginoidea virens . Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: On Oryza sativa and Zea mays . DISEASE: False smut of rice appears as olive-green, velvety, globose masses, up to 1 cm diam. in some of the ears of the inflorescence. The spore ball, beneath the dark layer of mature spores, is orange-yellow, paling inwards until it is almost white, as it ages it becomes almost black. The glumes are closely applied to the lower part of the spore ball which is at first covered with a membrane. Infection, producing similar symptoms, has been reported on the male inflorescence of Zea mays (8: 716) and on wild species of Oryza . GEOGRAPHICAL DISTRIBUTION: Widespread in the tropics, in U.S.A. (California and S.E. states) and in Italy (CMI Map 347, ed. 2, 1968). Records not yet mapped are Australia (NT), Costa Rica, Dominican Republic and Laos. TRANSMISSION: There appears to be no evidence for seed transmission and the conidia are probably viable for a short time only. The air-borne conidia have a diurnal periodicity with peak at 22.00 hr, numbers being very low between 04.00 and 16.00 hr (46, 316). The ascospores of the reported perfect state may also be air-dispersed.

Ustiloxin B, originally isolated from the fungus Ustilaginoidea virens, is a known inhibitor of microtubule assembly. Ustiloxin B is also produced by Aspergillus flavus and is synthesized through the ribosomal peptide synthesis pathway. In A. flavus, the gene cluster associated with ustiloxin B production contains 15 genes including those encoding a fungal C6-type transcription factor and ustiloxin B precursor. Although the koji mold Aspergillus oryzae, which is genetically close to A. flavus, has the corresponding gene cluster, it does not produce ustiloxin B, which may be explained by the fact that the gene encoding the transcription factor UstR is not expressed. Here, to investigate whether ustiloxin B can be produced by expressing ustR in A. oryzae, we constructed ustR expression (ustREX) strains and analyzed ustiloxin B production. In the ustREX strains, all genes in the cluster were up-regulated, in line with expression of ustR, and ustiloxin B produced. To elucidate whether the KexB protease is involved in the processing of the ustiloxin B precursor protein UstA, which has repeats of basic amino acid doublets resembling KexB target sites, we also constructed a ustREX strain with the ∆kexB genotype. Although ustR was expressed in this strain, ustiloxin B was barely detectable. This finding strongly suggests that KexB is required for ustiloxin B production. Electronic supplementary material The online version of this article (doi:10.1186/s13568-016-0181-4) contains supplementary material, which is available to authorized users.