Zearalenone formation by<Emphasis Type="Underline">Fusarium crookwellense</Emphasis> /Burgess,Nelson and Toussoun/ isolates from Poland and their pathogenicity towards cereals

Fusarium crookwellense /B.N. and T./ isolated from affected cereals in Poland formed zearalenone on wheat grain up to 602 mg/kg. Tested isolates have been found strong to severe pathogens of wheat, rye, triticale and barley seedlings and corn ears with pathogenicity similar to that ofF. culmorum andF. graminearum.     

Cultural characteristics and zearalenone production by strains of<Emphasis Type="Underline">Fusarium</Emphasis> from wheat

Conidia of the speciesFusarium culmorum /W.G.Sm./ Sacc. andFusarium graminearum Schwabe are characterized by variability in zearalenone production and dimensions depending on the substrate. The sporulation of isolates from some wheat eultivars have been deprived in vivo and in vitro in the first passage, but not their pathogenicity and toxic metabolites production. Nonsporulating strains produced lower quantités of zearalenone than sporulating ones. Liquid filtrates of such nonsporulating strains had a high phytotoxic effect on wheat caryopses. The crystalline toxin DAS /0,25 ug/ml/ had low phytotoxic effect on wheat caryopses.     

Infection ability of mycelium and spores of<Emphasis Type="Underline">Microdochium</Emphasis><Emphasis Type="Underline">nivale</Emphasis> (Fr) samuels hallett to<Emphasis Type="Underline">Lolium</Emphasis><Emphasis Type="Underline">Perenne</Emphasis> L.

Mycelium and spores ofMicrodochium nivale /Syn.Fusarium nivale/ were compared according to their ability to infect plants ofLolium perenne. The experiments were carried out according to the “cold chamber” method (Cormack, Lebeau 1956 modified by Pronczuk 1987). Between these two types of inoculum significant differences were found. The spore inoculum did not give any symptoms while the mycelial inoculum incited a severe disease in plants ofLolium perenne during one month of incubation.Under laboratory conditions it was found that the spore cultures ofMicrodochium nivale grew very slowly at 0 – 1°C, whereas their growth at 18 – 20°C was very fast. Growth of the mycelial cultures was not as profoundly affected by temperatures studied as the spore ones.It was concluded that to incite a disease the spore inoculum require longer incubation time than mycelial ones. The mycelial inoculum is more useful for screening of plants for resistsance.     

Zearalenone production in wheat cultivars infected with the fungus<Emphasis Type="Underline">Fusarium</Emphasis><Emphasis Type="Underline">graminearum</Emphasis> Schwabe

In wheat plants of the eultivars “Danubia”, “Agra”, “Selekta” and “Jubilejna” the fungusFusarium graminsarum Schwabe produced toxic metabolite zearalenone/F-2/ which simultaneously influenced the development of plants characterized by a lower germinating capacity, a reduced growth rate and a higher production of side branches. The presence ofFusarium graminearum was confirmed only in infected plants after plating of organs (root, stem base, stem) and soil on agar medium. The mycotoxin production is dependent on the pathogen development in host plants. The F-2 level progressed from the root into the soil, stem base and stem. The highest F-2 production was identified in cultivar “Selekta” the lowest in cultivar “Danubia”. The highest F-2 level (in all wheat eultivars) was identified in the stem base.     

Moniliformin and the European Corn Borer (<Emphasis Type="Italic">Ostrinia nubilalis</Emphasis>)

A representative survey was made of maize ears of the 1988 and 1989 crop in Austria to establish the influence of corn borer injuries onFusarium species involved in ear fusariosis andFusarium toxin production.TheFusarium species most frequently isolated from rot-damaged ears wereFsacchari var. subglutinans (about 50 %) andF. graminearum (about 30 %). There was a striking difference between theFusarium species of the Liseola and the Discolor section concerning their occurrence on corn borer-damaged ears. More than 80 % of the ears infected withF. sacchari var. subglutinans andF. verticillioides, but less than 15 % of the ears infected withF. graminearum, F. crookwellense andF. culmorum showed corn borer injuries.Toxin analyses of the infected ears corresponded to the known toxigenicity of the respectiveFusarium species. Ears infected withF. sacchari var. subglutinans contained moniliformin (up to 20 mg/kg), those infected withF. verticillioides fumonisin B₁ and B₂ (up to 15 mg/kg). In ears infected withF. graminearum, F. culmorum andF. crookwellense zearalenone (up to 40 mg/kg) and deoxynivalenol (up to 500 mg/kg) or nivalenol (up to 10 mg/kg), respectively, could be detected. Hence measures to combat the European corn borer will mainly reduce moniliformin and fumonisin contamination, but will affect zearalenone, deoxynivalenol and nivalenol contents of the ears to a much lesser extent.     

Contamination of freshly harvested maize kernels with<Emphasis Type="Underline">Fusarium</Emphasis> mycotoxins on Bihar state,India

Freshly harvested maize samples, collected from different fields of Bhagalpur during January-March, 1989, were analysed for the presence of Fusarium species and their toxins.F. moniliforme was most common followed byF. roseum,F. sporotrichioides,F. graminearum andF. equiseti. Different strains of these species produced zearalenone (11.2–28.2 μ/g), DON (0.3–2.9 μg/g) and T-2 (5.2–20.6 μg/g) toxins on mostrice medium. Fifteen per cent, out of 86 maize samples analysed, were found to be contaminated with various levels of above toxins, which occurred either alone or in groups. Toxin concentration in contaminated samples varied from 0.76–1.5 μg/g (ZEN), 0.41–202 μg/g (DON) and 0.55–2.92 μg/g (T-2).     

Fusariosis of spring barley cultivated in Lublin region

Diseases of spring barley in 1986–1988 seasons have been examined on barley plantations in Lublin region. Observations in eight weeks after sowing each year spring showed the occurrence of root rot and sheath rot in seedlings. As a result of mycological examination of infected seedlings 34 species of fungi were isolated:Fusarium spp. amounted up to 23% of all isolates. Each year,Fusarium culmorum andF.avenaceum were isolated, butF graminearum only in 1987. On all inspected fields there occurred plants with eye — spots or necrotic stripes on lower internodes. As a result of fungi isolation the colonies belonging to 30 species were identified from stems and roots of examined plants. There was about 35% of fusaria between isolates each year.Fusarium culmorum was most frequently isolated. This fungus both from stems with two mentioned kinds of symptoms and from roots was isolated.Fusarium avenaceum each year andFusarium graminearum in 1986 and 1988 were isolated. Mentioned there species were also isolated from kernels.     

Ecology and taxonomy of<Emphasis Type="Underline">Fusarium</Emphasis> species in Poland

The paper presents 21Fusarium species occurring in Poland on the field crops /mostly on cereals, maize, potato and Papilionaceae plants/, woody plants, grasses, vegetables and ornamentals as well as on kernels or seeds of these hosts and soils. Additionally the commonly observed symptoms on above-mentioned plants and the informations about regions of the highest disease occurrence are added.However the paper results mainly from authors’ investigation on theFusarium species occurrence in Poland, it encloses also the available, post-war literature data on the fusariosis in Poland in the past.Majority ofFusarium species cited had been identified according to Nelson et al, taxonomic system. Comparative listing of the monographs / 1,11, 21/ is presented.     

Pathogenicity of seed transmitted<Emphasis Type="Underline">Fusarium</Emphasis> spp. to triticale seedlings

In the conducted studies 13 species ofFusarium were isolated into pure culture from triticale seed. Their pathogenicity was assessed under laboratory and greenhouse conditions. Most of the species studied were highly pathogenic to the first leaf see-dlings of triticale ‘Grado’ and ‘Lasko’ under both sets of conditions. It was shown, that seed-transmitted Fusarium spp. considerably reduced the ability of seeds to germinate and incited seedling blight. On average, triticale ‘Lasko’ was more resistant toFusarium spp. than ‘Grado’, but in some instances a reverse reaction was observed.     

Characterisation of<Emphasis Type="Italic">fusarium graminearum</Emphasis> and<Emphasis Type="Italic">F. culmorum</Emphasis> isolates by mycotoxin production and aggressiveness to wheat

A total of 27Fusarium culmorum isolates from Germany and 41F. graminearum isolates from Kenya were investigated for aggressiveness and mycotoxin production on wheat ears. In addition, ergosterol content of the kernels from ears inoculated withF. graminearum was determined and theF. culmorum isolates were tested for mycotoxin productionin vitro. For both pathogens, isolates markedly differed in aggressiveness. 59% and 37% of theF. culmorum isolates produced NIV and DON, respectively,in vivo andin vitro. The DON-producing isolates also produced 3-acDONin vitro. The more aggressive isolates produced mainly DON while the less aggressive isolates produced mainly NIV. 12% and 85% of theF. graminearum isolates produced NIV and DON, respectively. The highly aggressive isolates produced higher amounts of DON, aggressiveness being highly correlated to DON content in the kernels. NIV-producing isolates were less aggressive. Ergosterol content of kernels was moderately correlated to aggressiveness but highly correlated to DON content. Disease severity was associated with kernel weight reduction.     

Karyo-taxonomic study of the genus<Emphasis Type="Italic">Pseudolysimachion</Emphasis> (<Emphasis Type="Italic">Scrophulariaceae</Emphasis>) in the Czech Republic and Slovakia

Flow cytometry was used to determine ploidy levels in the Czech and Slovak taxa of the genusPseudolysimachion (W.D.J. Koch)Opiz (=Veronica auct. p.p.,Scrophulariaceae). In total, 123 populations from the Czech Republic, Slovakia, Ukraine (one locality), Austria (one locality) and Hungary (one locality) were analyzed. InP. maritimum (L.)Á. Löve etD. Löve andP. spicatum (L.)Opiz, two cytotypes were found: diploid (2n=2x=34) and tetraploid (2n=4x=68). In both species the tetraploid cytotype predominated (P. maritimum: 41 tetraploid populations out of 45;P. spicatum: 57 tetraploid populations out of 58). The two cytotypes ofP. maritimum have no taxonomic significance because ploidy level is not obviously correlated with morphology, distribution pattern or ecology. Tetraploid populations ofP. spicatum belong to two morphologically different subspecies, subsp.spicatum and subsp.fischeri Trávní?ek. The diploid cytotype (one population only) should be provisionally classified as a third subspecies ofP. spicatum, which is morphologically similar to the Asian subsp.porphyrianum (Pavlov)Trávní?ek. Only diploid plants (2n=2x=34) ofP. orchideum (Crantz)Wraber were found; all 13 populations that were analyzed belong toP. orchideum s.str. One diploid population sample ofP. spurium subsp.foliosum (Waldst. etKit.)Holub (2n=2x=34) and one tetraploid sample ofP. incanum subsp.pallens (Host)Trávní?ek (2n=4x=68) were also analyzed. In addition, three tetraploid populations of hybrid origin were investigated:P. maritimum ×P. spicatum subsp.spicatum (one population) andP. maritimum ×P. spurium subsp.foliosum (two populations). While hybrid plants ofP. maritimum ×P. spicatum arose from tetraploid parental species, plants ofP. maritimum ×P. spurium probably resulted from a cross between tetraploidP. maritimum and diploidP. spurium. The putative origin and evolutionary importance of polyploids in thePseudolysimachion are discussed.     

Biotechnological potential of a rhizosphere <Emphasis Type="Italic">Pseudomonas</Emphasis><Emphasis Type="Italic">aeruginosa</Emphasis> strain producing phenazine-1-carboxylic acid and phenazine-1-carboxamide

Bacterial phenazine metabolites belong to a group of nitrogen-containing heterocyclic compounds with antimicrobial activities. In this study, a rhizosphere Pseudomonas aeruginosa strain PA1201 was isolated and identified through 16S rDNA sequence analysis and fatty acid profiling. PA1201 inhibited the growth of various pathogenic microorganisms, including Rhizotonia solani, Magnaporthe grisea, Fusarium graminearum, Xanthomonas oryzae pv. oryzae, Xanthomonas oryzae pv. oryzicola, and Staphylococcus aureus. High Performance Liquid Chromatography showed that PA1201 produced high levels of phenazine-1-carboxylic acid (PCA), a registered green fungicide ‘Shenqinmycin’ with the fermentation titers of 81.7 mg/L in pigment producing medium (PPM) and 926.9 mg/L in SCG medium containing soybean meal, corn steep liquor and glucose. In addition, PA1201 produced another antifungal metabolite, phenazine-1-carboxaminde (PCN), a derivative of PCA, with the fermentation titers of 18.1 and 489.5 mg/L in PPM and SCG medium respectively. To the best of our knowledge, PA1201 is a rhizosphere originating P. aeruginosa strain that congenitally produces the highest levels of PCA and PCN among currently reported P. aeruginosa isolates, which endows it great biotechnological potential to be transformed to a biopesticide-producing engineering strain.     

Occurrence and distribution of <Emphasis Type="Italic">Microdochium nivale</Emphasis> and <Emphasis Type="Italic">Fusarium</Emphasis> species isolated from barley,durum and soft wheat grains in France from 2000 to 2002

Fusarium Head Blight of small grain cereal is a disease of growing concern in Europe. Along with Microdochium nivale, several species of Fusarium may be associated with the disease, including species that are potentially toxigenic. This paper describes the results of a large scale survey of the variety and frequency of different Fusarium species and M. nivale in France. A total of 749 soft wheat, durum wheat and barley samples were collected and analyzed from 2000 to 2002. The most frequent species isolated were F.graminearum, F. avenaceum and F. poae. The frequency of F. poae seems to have increased while M.nivale and F. culmorum appear less frequent than previously described in France. Other Fusarium species detected in decreasing prevalence were F. tricinctum, F. equiseti, F. acuminatum, F. sambucinum, F.sporotrichioides, F. moniliforme, F. heterosporum, F. subglutinans and F. oxysporum. All the most frequent pathogenic species and also the less pathogenic ones were frequently associated with individual fields. The implications of these associations for the protection of cereals crops and for contamination by mycotoxins are discussed.     

Development and relations of <Emphasis Type="Italic">Fusarium culmorum</Emphasis> and <Emphasis Type="Italic">Pseudomonas fluorescens</Emphasis> in soil

The development of Fusarium culmorum and Pseudomonas fluorescens in soil, and the relations between them, were studied using membrane filters containing the fungus, the bacterium, or both microorganisms; the filters were incubated in soil. F. culmorum was identified by indirect immunofluorescence; the GUS-labeled strain was used to visualize P. fluorescens. It was found that F. culmorum introduced in soil can develop as a saprotroph, with the formation of mycelium, macroconidia, and a small amount of chlamydospores. Introduction of glucose and cellulose resulted in increased density of the F. culmorum mycelium and macroconidia. P. fluorescens suppressed the development of the F. culmorum mycelium in soil, but stimulated chlamydospore formation. Decreased mycelial density in the presence of P. fluorescens was more pronounced in soil without additions and less pronounced in the case of introduction of glucose or cellulose. F. culmorum had no effect on P. fluorescens growth in soil.     

<Emphasis Type="Italic">qRfg3</Emphasis>, a novel quantitative resistance locus against <Emphasis Type="Italic">Gibberella</Emphasis> stalk rot in maize

Key message

A quantitative trait locus  qRfg3 imparts recessive resistance to maize Gibberella stalk rot. qRfg3 has been mapped into a 350-kb interval and could reduce the disease severity index by ~26.6%.

Abstract

Gibberella stalk rot, caused by the fungal pathogen Fusarium graminearum, severely affects maize yield and grain quality worldwide. To identify more resistance quantitative trait loci (QTLs) against this disease, we analyzed a recombinant inbred line (RIL) population derived from a cross between resistant H127R and susceptible C7-2 inbred lines. Within this population, maize resistance to Gibberella stalk rot had high broad-sense heritability. A major QTL, qRfg3, on chromosome 3 was consistently detected across three field trials, accounting for 10.7–19.4% of the total phenotypic variation. Using a progeny-based sequential fine-mapping strategy, we narrowed qRfg3 down to an interval of ~350 kb. We further demonstrated that qRfg3 is a recessive resistance locus to Gibberella stalk rot that reduced the disease severity index by ~26.6%. Both the gene location and recessive genetic mode distinguish qRfg3 from other stalk rot resistance loci. Hence, qRfg3 is valuable as a complement to existing resistance QTLs to improve maize resistance to Gibberella stalk rot.

     

Chromosome number variability in central european members of the<Emphasis Type="Italic">Festuca ovina</Emphasis> and<Emphasis Type="Italic">F. pallens</Emphasis> groups (sect.<Emphasis Type="Italic">Festuca</Emphasis>)

Chromosome numbers for 98 plants ofF. pallens, 19 ofF. psammophila, F. belensis andF. vaginata, and 44 ofF. ovina (originating from Austria, the Czech Republic, Germany, Slovakia and Latvia) are given. In addition to theF. ovina andF. pallens groups, chromosome counts for the following taxa are also reported:F. alpestris (2n=14) reported for the first time in this work,F. amethystina subsp.amethystina (2n=28),F. brevipila (2n=42),F. cinerea (2n=28),F. rupicola subsp.rupicola (2n=42) andF. versicolor subsp.versicolor (2n=14).InF. pallens, two ploidy levels (2n=2x=14+0-1B, 2n=4x=28+0-1B) as well as two natural triploid plants (2n=21+0-1B), were found. In addition to the fourF. pallens types that have been distinguished in Austria, one new tetraploid type (F. pallens “scabrifolia”) from the Czech Republic and Germany is reported and its taxonomy is discussed. The distributions of the Oberösterreich-Niederösterreich and Pannonisches-HügellandF. pallens types outside of Austria are documented.Only the diploid chromosome number (2n=14) was found inF. psammophila andF. vaginata. Chromosome numbers forF. psammophila subsp.muellerstollii andF. belensis (both 2n=14) were determined here for the first time. Two ploidy levels, 2n=14+0-5B corresponding toF. ovina subsp.ovina and 2n=28 corresponding toF. ovina subsp.guestphalica andF. cf.duernsteinensis were confirmed inF. ovina. Differences in chromosome structure (simple and multiple secondary constrictions) betweenF. pallens as opposed toF. psammophila andF. vaginata are discussed. A complete survey of published chromosome counts for Central European species from theF. ovina andF. pallens groups is included.     

Investigation of stored wheat mycoflora,reporting the<Emphasis Type="Italic">Fusarium</Emphasis> cf.<Emphasis Type="Italic">langsethiae</Emphasis> in three provinces of Iran during 2007

Wheat is the most important cereal produced in Iran. A mycological survey was carried out for the first time, on the stored wheat samples in Tehran, East Azarbayejan and Mazandaran provinces in 2007. Exogenous and endogenous fungi, were isolated by the method of flotation with Malachite green agar (MGA 0.25) and Freeze blotter techniques respectively. In this study, 46 species belonging to 23 different genera were isolated.Cladosporium spp. (57.1–89.2%) andAlternaria spp. (82.4–100%) species were the predominant fungal species identified as endogenous mycoflora. The predominant exogenous fungi werePenicillium spp. (78.4–92.8%) andAspergillus spp. (71.4–85.7%) species.Fusarium proliferatum was the most prevalent species ofFusarium isolates.Aspergillus niger (39.4%) andAspergillus flavus (36.7%) were the predominantAspergillus species identified as exogenous mycoflora.Aspergillus flavus (26.6%) was the predominantAspergillus species identified as endogenous mycoflora. Flotation method with MGA 0.25 recommended for isolating of hyaline fungi from wheat cereals. In this study one isolate fromFusarium species was isolated on the basis of morphology and ribosomal internal transcribed spacer classified asFusarium langsethiae but on the basis of partial translation elongation factor-1alpha gene grouped withFusarium sporotrichioides. To our knowledge, this is the first report aboutF. cf.langsethiae in Iran and Asia.     

Mycotoxins and fungi accompanying wheat head fusariosis in Poland

The occurrence of wheat head fusariosis in various regions of Poland was observed in 1985 and 1986. The incidence of fusariosis was usually low — about 0,01% — only on South — East in some localities reached 5 – 20%. The most important species isolated from infected heads were :Fusarium culmorum F.grami nearurn,F.ni vale andF.avenaceum, in addition to whichF.crookwel1ense,F.eqiseti,F.subqluti nans andF.tricinctum (sensu Nelson et al.1983) were observed. Deoxynivalenol was present in 100% examined kernels subsamples at level 5–18 mg/kg and 3-acetyl deoxyn i val enol in 70% at level 1–3 mg/kg. The mycotoxins amount in chaff was 1,4 to 2,6 and 1,4 to 11 times higher (DON and 3AcD0N resp.) than in kernels.     

A study of the correlation between the amount of deoxynivalenol in grain of wheat and triticale and percentage of<Emphasis Type="Italic">Fusarium</Emphasis> damaged kernels

The correlation between the amount of deoxynivalenol (DON) and the percentage ofFusarium damaged kernels (FDK) in samples of wheat and triticale was studied.Samples of naturally infected wheat grain, collected in 1986, 1987 and 1988 and of triticale collected in 1986 were used.Additionally, artificial inoculated wheat samples (10 genotypes inoculated with 3F. Culmorum strains of weak, medium and severe pathogenicity and samples of 10 triticale genotypes inoculated withF. culmorum. andF. graminearun) were studied. Using statistical methods (the variance analysis, method of least significant difference (LSD), orthogonal contrast (OC) and minimum within groups sum of squares criterion (MSSC)), the samples were divided into two groups with respect to the attribute DON/FDK.To the first group belong samples of wheat and triticale, of which the heads were artificially inoculated with severely pathogenic strainsF. culmorum. In the samples of this group the amount of DON in kernels damaged withFusarium increased by 0,46 mg/kg per 1% of FDK.In the second group, consisting of naturally infected samples and samples from artificially inoculated heads the amount of DON increased 0,30 mg DON/kg per 1% of FDK.The equation for the calculation of approximated amount of DON in farm and commercial lots of wheat and triticale after examination of percentage of FDK is given.     

Expression of sorghum gene <Emphasis Type="Italic">SbSGL</Emphasis> enhances grain length and weight in rice

Grain weight is a major determining factor of rice (Oryza sativa L.) yield and the comprehensive embodiment of grain length, width, and thickness. Here, we describe the molecular and functional characterization of SbSGL (Sorghum bicolor L. stress tolerance and grain length), a sorghum gene that encodes a putative member of the DUF1645 protein family of unknown function. Expression of SbSGL in rice promoted cell division and grain filling, which affected an array of traits of rice, including grain length, grain weight, and seed setting rate. Expression of SbSGL also affected the expression of genes related to the plant cell cycle and grain size.