J. Chełkowski

Wheat-infectingFusarium species in Poland — their chemotypes and frequencies revealed by PCR assay

ThreeFusarium species:F. graminearum, F. culmorum andF. cerealis were identified in laboratory cultures and in sporodochia from spikelets of scabby wheat. SCAR (sequence characterized amplified region) primers were used to identifyFusarium species and nivalenol (NIV) and deoxynivalenol (DON) chemotypes within species in laboratory cultures and field collected heads harvested in 2006. Results from PCR analyses confirmed preliminary identifications of species on the basis of examination of macroconidia under a light microscope and identification of cultures on agar media. NIV and DON (3Ac-DON and 15Ac-DON) chemotypes were identified using PCR assay. Among samples and isolates ofF. graminearum, the 15Ac-DON chemotype dominated, and among those whereF. culmorum was identified, the 3Ac-DON chemotype prevailed. Only 5 of the 41 isolates ofF. graminearum tested, displayed the NIV chemotype. An increase in the frequency ofF. graminearum and a decrease in the frequency ofF. culmorum were found during 1998 to 2006.

Species diversity of Trichoderma in Poland

In the present study, we reinvestigate the diversity of Trichoderma in Poland utilizing a combination of morphological and molecular/phylogenetic methods. A total of 170 isolates were collected from six different substrata at 49 sites in Poland. These were divided among 14 taxa as follows: 110 of 170 Trichoderma isolates were identified to the species level by the analysis of their ITS1, ITS2 rDNA sequences as: T. harzianum (43 isolates), T. aggressivum (35), T. citrinoviride (11), T. hamatum (9), T. virens (6), T. longibrachiatum (4), T. polysporum (1), and T. tomentosum (1); 60 isolates belonging to the Viride clade were identified based on a fragment of the translation-elongation factor 1-alpha (tef1) gene as: T. atroviride (20 isolates), T. gamsii (2), T. koningii (17), T. viridescens (13), T. viride (7), and T. koningiopsis (1). Identifications were made using the BLAST interface in TrichOKEY and TrichoBLAST (http://www.isth.info). The most diverse substrata were soil (nine species per 22 isolates) and decaying wood (nine species per 75 isolates). The most abundant species (25%) isolated from all substrata was T. harzianum.

Fusarium head blight of wheat: pathogenic species and their mycotoxins.

Fusarium head blight is a wheat disease of global importance and devastating impact in some years, especially in regions with high cereal production. Wheat grain contamination with mycotoxins is th...

Ear rot susceptibility and mycotoxin contamination of maize hybrids inoculated with Fusarium species under field conditions

The development of new maize hybrids with resistance to Fusarium infection is an effective means of minimizing the risk of mycotoxin contamination. Several maize hybrids have been investigated for Fusarium ear rot and accumulation of fumonisin B1 (FB1), fumonisin B2 (FB2), beauvericin (BEA) and fusaproliferin (FP) after artificial inoculation in the field with toxigenic strains of Fusarium verticillioides and Fusarium proliferatum. The year of inoculation had a significant influence on the disease severity and mycotoxin accumulation in maize kernels. Of all the hybrids tested, only Mona exhibited resistance to ear rot caused by F. verticillioides and produced low levels of fumonisins during three years of experiments. In Fusarium-damaged kernels (FDK), fumonisin B1, fumonisin B2, beauvericin and fusaproliferin were detected at concentrations much higher (up to 10–20 times) than in healthy-looking kernels (HLK). Animal and human exposure to these mycotoxins can be drastically reduced by removing mouldy and visibly damaged kernels from the commodity.

Deoxynivalenol, nivalenol and moniliformin in wheat samples with head blight (scab) symptoms in Poland (1998–2000)

Fusarium head blight (scab) epidemics of wheat occurred in Żuławy (Northern Poland) during 1998 and in Wielkopolska (West) and in Southern regions of Poland in 1999. Four species were identified in wheat heads with scab symptoms: Fusarium culmorum, Fusarium graminearum, Fusarium avenaceum and Microdochium nivale. A significant increase in the frequency of F. graminearum (between 23% and 38%), was observed, compared to about 10% during the previous decade. The mycotoxins deoxynivalenol (DON), nivalenol (NIV) and moniliformin (MON) in amounts up to 24.3, 14.2 and 1.72mgkg−1respectively, were identified in kernels samples.

Head infection and accumulation of Fusarium toxins in kernels of 12 barley genotypes inoculated with Fusarium graminearum isolates of two chemotypes

Twelve barley genotypes were inoculated with two F. graminearum isolates of different chemotype I1 #148 (producing nivalenol/deoxynivalenol) and I2 #108 (deoxynivalenol/acetyldeoxynivalenol). For both I1 and I2 isolates, respectively, reductions (%) in number of kernels head-1 10.6 and 14.3; yield 39.6 and 35.7; weight of 1000 kernels 36.9 and 23.2 were observed in inoculated plants from control values. Chemical analysis revealed the presence (average concentration mg kg-1) of deoxynivalenol (1.3) and nivalenol (3.2) in kernels of all genotypes inoculated with the I1 isolate, and zearalenone (0.2) in three samples. After inoculation with the I2 isolate, deoxynivalenol (37.8) and zearalenone (0.4) were found in kernels of all genotypes, while 3-acetyldeoxynivalenol and 15-acetyldeoxynivalenol, respectively, were determined in five and four samples only. No significant correlation between examined characteristics was found for either the I1 or I2 isolate. The results obtained contribute information on the accumulation of toxins in cereal grain inoculated with F. graminearum isolates of different chemotypes.

Fusarium species, zearalenone and deoxynivalenol content in preharvest scabby wheat heads from Poland

High incidence of Fusarium head blight occurred in Northern and Southern Poland in the 2009 season. Head samples from 106 wheat fields were collected before harvest from Northern, Central and South...

The significance of cellulolytic enzymes produced by Trichoderma in opportunistic lifestyle of this fungus.

The degradation of native cellulose to glucose monomers is a complex process, which requires the synergistic action of the extracellular enzymes produced by cellulolytic microorganisms. Among fungi, the enzymatic systems that can degrade native cellulose have been extensively studied for species belonging to the genera of Trichoderma. The majority of the cellulolytic enzymes described so far have been examples of Trichoderma reesei, extremely specialized in the efficient degradation of plant cell wall cellulose. Other Trichoderma species, such as T. harzianum, T. koningii, T. longibrachiatum, and T. viride, known for their capacity to produce cellulolytic enzymes, have been isolated from various ecological niches, where they have proved successful in various heterotrophic interactions. As saprotrophs, these species are considered to make a contribution to the degradation of lignocellulosic plant material. Their cellulolytic potential is also used in interactions with plants, especially in plant root colonization. However, the role of cellulolytic enzymes in species forming endophytic associations with plants or in those existing in the substratum for mushroom cultivation remains unknown. The present review discusses the current state of knowledge about cellulolytic enzymes production by Trichoderma species and the encoding genes, as well as the involvement of these proteins in the lifestyle of Trichoderma.

Zearalenone lactonohydrolase activity in Hypocreales and its evolutionary relationships within the epoxide hydrolase subset of a/b-hydrolases

AbstractBackgroundZearalenone is a mycotoxin produced by several species of Fusarium genus, most notably Fusarium graminearum and Fusarium culmorum. This resorcylic acid lactone is one of the most important toxins causing serious animal and human diseases. For over two decades it has been known that the mycoparasitic fungus Clonostachys rosea (synonym: Gliocladium roseum, teleomorph: Bionectria ochroleuca) can detoxify zearalenone, however no such attributes have been described within the Trichoderma genus.ResultsWe screened for the presence of zearalenone lactonohydrolase homologs in isolates of Clonostachys and Trichoderma genera. We report first finding of expressed zearalenone lactonohydrolase in Trichoderma aggressivum. For three isolates (T. aggressivum, C. rosea and Clonostachys catenulatum isolates), we were able to reconstruct full coding sequence and verify the biotransformation ability potential. Additionally, we assessed progression of the detoxification process (in terms of transcript accumulation and mycotoxin decomposition in vitro). In silico, search for origins of zearalenone lactonohydrolase activity in model fungal and bacterial genomes has shown that zearalenone lactonohydrolase homologs form a monophyletic fungal clade among the a/b hydrolase superfamily representatives. We corroborated the finding of functional enzyme homologs by investigating the functional sites (active site pocket with postulated, noncanonical Ser-Glu-His catalytic triad) conserved in both multiple sequence alignment and in homology-based structural models.ConclusionsOur research shows the first finding of a functional zearalenone lactonohydrolase in mycoparasitic Trichoderma aggressivum (an activity earlier characterised in the Clonostachys rosea strains). The supporting evidence for presence and activity of functional enzyme homologs is based on the chemical analyses, gene expression patterns, homology models showing conservation of key structural features and marked reduction of zearalenone content in cultured samples (containing both medium and mycelium). Our findings also show divergent strategies of zearalenone biotransformation ability (rapid induced expression and detoxification vs. gradual detoxification) present in several members of Hypocreales order (Trichoderma and Clonostachys genera). The potential for lactonhydrolase activity directed towards zearalenone and/or similar compounds is likely ancient, with homologs present in several divergent filamentous fungi among both Sordariomycetes (Bionectria sp., Trichoderma sp., Apiospora montagnei) and Leotiomycetes (Marssonina brunnea f. sp. ‘multigermtubi’).

Cyclic hexadepsipeptides in wheat field samples and esyn1 gene divergence among enniatin producing Fusarium avenaceum strains

Fusarium avenaceum is one of the most important pathogenic species in agricultural and forest environments of moderate climate, particularly in cereals and legume pulse crops. Numerous mycotoxins can be synthesized by the species, with moniliformin and enniatins (ENN) being the prevailing metabolites. The aims of this work were to examine the amounts of ENN and beauvericin present in naturally contaminated field samples of wheat kernels and chaffs collected in Poland in 2005 and 2009 from heads infected with F. avenaceum, and to reveal the divergence of the esyn1 gene among F. avenaceum strains of different origin. ENN-B and ENN-B1 were the major metabolites identified in wheat field samples. Chaff fractions contained significantly more mycotoxins than grain. Samples originating from 2005 were in general less contaminated with ENN than those from the 2009 season. The highest amount of ENN-B found in grain was 28,520 μg/kg. Beauvericin was only found in trace amounts in all the samples tested. F. avenaceum...