Repozytorium

Durum wheat production in Italy is economically of great importance. Fusarium graminearum is the main fusarium head blight (FHB) causal agent in wheat, reducing both yield and grain quality. F. graminearum produces several mycotoxins and, among trichothecenes, deoxynivalenol (DON) and nivalenol (NIV) are the most studied for their toxicity towards humans and animals. DON-producing isolates can be further distinguished on the basis of the predominant acetyl-DON derivative in 3-acetyldeoxynivalenol (3-ADON) or 15-acetyldeoxynivalenol (15-ADON). In order to evaluate possible mycotoxin contamination risks in food, it is very important to know which chemotype is the prevalent in a F. graminearum population.F. graminearum sensu stricto strains were collected from symptomatic durum wheat heads and grains of several naturally infected fields located mostly in Emilia – Romagna, The Marche, Lazio, Tuscany and Umbria. A multiplex PCR in the region of genes Tri12, located in the terminal gene cluster of trichothecenes, was used to characterize 187 single-spore isolates of F. graminearum as NIV, 3-ADON and 15-ADON chemotypes. All the three chemotypes were present in the F. graminearum population studied. The most frequent chemotype was 15-ADON (83.4%), followed by 3-ADON (10.7%) and NIV (5.9%). NIV-producing isolates were found only in Emilia-Romagna (3.5%), Umbria (33.3%) and The Marche (5.7%)...

The mitogen-activated protein kinase (MAPK) MGV1 has been knocked out in Fusarium graminearum to produce the mutant FgΔMGV1.  The mutant displays complementary phenotypes concerning deoxynivalenol (DON) and butenolide (BT) biosynthesis in vitro.  In the rich medium 15-ADON accumulates are at low levels as detected by HPLC, whereas the accumulation of BT is substantial in FgΔMGV1.  This is supported by the high expression of butenolide cluster genes in the mutant compared to the wild-type strain.  Under nutrient-limiting conditions, where DON biosynthesis is normally favoured, the expression of genes of the trichothecene cluster does not differ between the two strains.  However, the accumulation of 15-ADON is vastly different in FgΔMGV1.  There is a reduction of 15-ADON accumulation with a concomitant accumulation of a novel compound.  Although gene clusters comprising the synthesis of DON and BT have been identified, their regulation at the molecular level has not been fully elucidated.  Since the expression levels of two regulatory genes from the trichothecene gene cluster and three regulatory genes from the butenolide gene cluster remained unchanged between WT and FgΔMGV1, we suggest that differential accumulation of both BT and DON biosynthesis is at least partially under post-transcriptional and/or post-translational control...

Fusarium head blight (FHB) is a major disease of wheat in most wheat growing areas of the world. Resistance to FHB is a key trait for CIMMYT and many wheat breeding programs worldwide. New plant phenotyping techniques such as quantification of fungal biomass using real-time PCR have become available recently. CIMMYT’s approach is to test new techniques for their feasibility and to apply them in routine disease screening programs if they prove to be valuable.Two sets of spring wheat genotypes assembled on the basis of low (group 1) and high (group 2) FHB index observed in previous years, were phenotyped and genotyped in CIMMYT’s FHB screening program. Phenotyping consisted of visual disease scoring (FHB index), mycotoxin analysis (DON) and quantification of fungal biomass. Apart from the FHB index, the two groups differed slightly in terms of DON accumulation although no differences were observed for average fungal biomass. This observation combined with the lack of correlation between disease symptoms and amount of fungal biomass suggested that some useful information may not be considered to discriminate resistant from susceptible genotypes when field selection is solely based on visual scoring results. DON/biomass-ratio was assessed for all genotypes and was found to be higher in the more resistant group 1 contrary to expectiations. An increase in DON production resulting from a stress or from resistance is discussed as a possible hypothesis. The determination of fungal biomass proved to be potentially valuable as a phenotyping tool. Genotyping results also showed that new genotypes harboring moderate levels of resistance and differing from traditional sources of scab resistance become available...

Fusarium graminearum and related species causing Fusarium head blight of cereals and ear rot of maize produce the trichothecene toxin and virulence factor deoxynivalenol (DON). Plants can detoxify DON to a variable extent into deoxynivalenol-3-O-glucoside (D3G). We have previously reported the DON inactivating glucosyltransferase (UGT) AtUGT73C5 from Arabidopsis thaliana (Poppenberger et al, 2003). Our goal was to identify UGT genes from monocotyledonous crop plants with this enzymatic activity. The two selected rice candidate genes with the highest sequence similarity with AtUGT73C5 were expressed in a toxin sensitive yeast strain but failed to protect against DON. A full length cDNA clone corresponding to a transcript derived fragment (TDF108) from wheat, which was reported to be specifically expressed in wheat genotypes containing the quantitative trait locus Qfhs.ndsu-3BS for Fusarium spreading resistance (Steiner et al, 2009) was reconstructed. Only cDNAs with a few sequence deviations from TF108 could be cloned. However, toxin sensitive yeast strains expressing this wheat UGT cDNA did not show a resistant phenotype. The main difficulty in generating full length cDNAs for functional validation by heterologous expression in yeast is the enormous number of the UGT superfamily members in plants, with 107 UGT genes plus some pseudogenes in Arabidopsis thaliana and about 150 putative UGT genes in grasses. We conclude that neither sequence similarity nor inducibility are good predictors of substrate specificity...

Species within the genus Fusarium produce a diverse range of mycotoxins, many of which have significant impacts on human health. Of the five generally recognised major mycotoxins, three (fumonisins, deoxynivalenol (DON) and zearalenone (ZON)) are produced by Fusaria. Apart from DON, other trichothecenes such as T-2 toxin, have received considerable international attention due to their impact on human health. The fumonisins, which occur ubiquitously in maize and its products, have been linked to oesophageal cancer, liver cancer and neural tube defects. DON, a frequent contaminant of maize, wheat and their products, although showing no carcinogenic potential, is immunomodulatory and produces emesis and growth retardation in animals. ZON is a naturally occurring endocrine disrupting chemical. Acute exposure to these mycotoxins has in each case been linked to outbreaks of human disease – gastro-intestinal effects in the case of fumonisins and DON, and precocious pubertal changes in the case of ZON. Concern over their toxicological effects has led to risk assessments by the Joint FAO/WHO Expert Committee on Food Additives (JECFA), which has set maximum tolerable daily intakes (TDI) of 2 µg/ kg body weight (bw) for fumonisins and 0.5 µg/kg bw for ZON. The initial TDI set for DON, namely 1 µg/kg bw has recently been updated by JECFA to include both 3- and 15-acetylDON. Apart from the above mycotoxins, a number of other secondary metabolites (moniliformin, beauvericin and fusaproliferin) are produced by different Fusaria and their effects on human health, either alone or in combination with other mycotoxins, is largely unexplored...

Field trials conducted at the Institute of Agriculture, Lithuanian Research Centre for Agriculture and Forestry (central part of Lithuania) in 2009 were aimed to evaluate the effect of fungicides on Fusarium Head Blight (FHB) in a naturally infected field. A single application of dimoxystrobin + epoxiconazole (Swing Gold), prothioconazole (Proline), metconazole (Juventus), tebuconazole (Folicur), prothioconazole + tebuconazole (Prosaro) was applied to winter wheat cv. ‘Zentos’ at the manufacturer’s recommended doses at anthesis (BBCH 65). The FHB incidence and severity were assessed at milk and hard maturity stages. The percentage of Fusarium infected grain and deoxynivalenol (DON), zearalenone (ZEN) and T-2 toxin (T-2) concentrations in harvested grain were determined. In all fungicide treated plots a significant reduction of FHB incidence and severity was determined; however the fungicides did not exert any effect on the amount of Fusarium–infected grain as compared with the untreated control. A reduction of DON, ZEN and T-2 contents in grain was determined in tebuconazole treatments. Fusarium avenaceum (Fr.) Sacc, F. culmorum (W. G. Sm.) Sacc., F. poae (Peck) Wollenw, F. sporotrichioides Sherb. and F. tricinctum (Corda) Sacc were identified in wheat grain, F. poae was prevalent...

In the present work Fusarium DNA levels of deoxynivalenol (DON)-producing F. graminearum and F. culmorum and T-2/HT-2-producing F. langsethiae and F. sporotrichioides were compared to DON and T-2/HT-2 levels in Finnish (19 oat samples) and Estonian (3 oat, 8 wheat and 9 barley) grain samples of the year 2008. The Finnish oat samples were selected based on high (

Fusarium head blight (Fusarium graminearum Schw.) is one of the most dangerous fungal diseases in wheat production decreasing grain yield up to 50% or more what depends on both environmental factors and genotype. Testing of inoculated artificially new Bc winter wheat lines for their resistance to FHB was the objective of the study.In 2008 and 2009 two and five lines of tested 12 new ones respectively were shown to be more resistant than Sana cultivar used as a standard. Majority of the winter wheat lines exceeded level of resistance standing out by Bc 7 and Bc 1 and Bc Lira variety as the highest yielding variety was registered by CCVR in 2009...

Fusarium head blight (FHB, scab) is a widespread disease of cereals, including barley (Hordeum vulgare L.), causing substantial yield and quality loss. Varieties with resistance is provide the greatest potential for reducing FHB. In the present study, we adapted cut-spike method for screening FHB severity among 126 spring barley genotypes. The collection consisted of Latvian varieties and perspective breeding lines and foreign varieties with specific quality traits important for food purposes and resistance to several diseases. Screening was repeated for two years, 2008 and 2009. Differences between genotypes in FHB resistance were observed. Two years data showed that genotype has a significant effect on FHB resistance (p

Fusarium Head Blight (FHB) is a worldwide disease affecting wheat, barley and other grains, reducing kernel weight and grain yield; infected seeds may contain a large number of mycotoxins, including trichothecenes of type A and B. These compounds have already been associated with human and animal toxicoses. Most common species causing the disease are F. graminearum, F. culmorum and F. avenaceum, but in the last few years a gradual increase in incidence of another species, F. poae, has been reported. In general terms, F. poae is a relatively weak pathogen, but its contribute to the increase of mycotoxins level still has to be clarified.Durum wheat is widely cultivated in the central part of Italy, however the effective incidence of F. poae in this area still has to be investigated.In order to monitor Fusarium risk, we collected dozens of F. poae strains on seeds and glumes of durum wheat coming from some of the most important cultivated areas of Central Italy. Every isolate was identified both by microscope observation and by PCR assay with the primer pair Fp82 F/R. Strains were therefore subjected to a more accurate molecular characterization by Translation Elongation Factor 1-alpha (TEF-1α) gene sequencing...

Fusarium head blight is a  very important disease of small grain cereals with  F. graminearum as one of the most important causal agents. It not only causes reduction in yield and quality but from a  human and animal healthcare point of view, it produces mycotoxins such as deoxynivalenol (DON) which can accumulate to toxic levels. Little is known about external triggers influencing DON production. In the present work, a  combined in vivo/in vitro approach was used to test the effect of sub lethal fungicide treatments on DON production. Using a  dilution series of prothioconazole, azoxystrobin and prothioconazole + fluoxastrobin, we demonstrated that sub lethal doses of prothioconazole coincide with an increase in DON production 48 h after fungicide treatment. In an artificial infection trial using wheat plants, the in vitro results of increased DON levels upon sub lethal prothioconazole application were confirmed illustrating the significance of these results from a  practical point of view. In addition, further in vitro experiments revealed a  timely hyperinduction of H2O2 production as fast as 4h after amending cultures with prothioconazole. When applying H2O2 directly to germinating conidia, a  similar induction of DON-production by  F. graminearum was observed. The effect of sub lethal prothioconazole concentrations on DON production completely disappeared when applying catalase together with the fungicide. These cumulative results suggest that H2O2 induced by sub lethal doses of the triazole fungicide prothioconazole acts as a  trigger of DON biosynthesis. In a  broader framework, this work clearly shows that DON production by the plant pathogen  F. graminearum is the result of the interaction of fungal genomics and external environmental triggers...

Water melon growers in Hungary have been recently reported a disease resembling that of Fusarium wilt developed on Fusarium resistant cultivars. Diseased samples from different regions of Hungary were collected in 2008 and 2009. The pathogen has been successfully isolated and identified as Fusarium solani. All of the isolates are host specific, but are very aggressive on water melon cultivars resistant to F. oxysporum f.sp. niveum. Severe infections occurred only in those fields where water melon has been grown continously for several years, but the pathogen is present in the soil of other fields as well...

The aim of the study was to determine if azoxystrobin and metconazole used for the control of wheat FHB at half, full, and quarter more the recommended dose rate may affect in differentiated way on the occurrence of Fusarium spp. and their ability to mycotoxin production in harvested grain, in wheat ears artificially inoculated with two DON-producing isolates of F. culmorum. Macroscopic evaluation showed high incidence of fusariosis. Plant health in the plots where the heads were artificially inoculated and fungicide was not applied was similar to the protected ones. Only increasing the dose metconazole resulted in a stronger reduction of fusariosis. The advantageous effect of azoxystrobin was not observed. Mycological analysis of harvested grain showed the presence of a number of F. culmorum, but from samples sprayed with metconazole it was isolated in smaller quantities. Also F. avenaceum, F. graminearum, F. poae and F. tricinctum were isolated. Molecular analysis showed the presence of F. culmorum in all samples of harvested grain. Also genes from Tri cluster were identified, involved in the synthesis of type-A and type-B trichothecenes - especially DON and 3Ac-DON. Chromatography revealed the presence of small quantities of mycotoxins. In all samples DON and 3Ac-DON were predominant. In general, F. culmorum isolate, which caused weaker symptoms of FHB and was less numerously isolated from grain that the other one, produced smaller amounts of mycotoxins. Samples protected with azoxystrobin contain the largest quantities of DON. Effect of different doses of fungicides on the number of mycotoxins was not clearly established...

In pursuing FHB resistance in wheat, 30 years of conventional breeding efforts in Eastern Canada have brought some progress. Substantial investment and the application in recent years of marker-assisted selection have to date, however, failed to produce agronomic lines that resist FHB as well as Sumai 3. We present here an alternative path, described as the systemic approach. Rather than seeking to introgress specific putative resistance genes, it subjects target germplasm to regimes of repeated cycles of multiple, interacting (biotic and abiotic) stresses in which desirable traits – not always adequately expressed in parental lines – are identified and selected. How can such a seemingly counterintuitive process work? The systemic approach views desired resistance as arising from the interactions of complex regulation mechanisms mediating how a host responds when a pathogen attacks. These constituents of resistance should thus not always be understood simply as discrete Mendelian units. In repeated rounds of selection, the systemic approach captures those rare individuals that embody optimal interactions of traits, and advances them as founders of lines that resist FHB more effectively than if selection focused on FHB alone. In Quebec, we have chosen to select wheat populations under combined pressure from barley yellow dwarf virus (BYDV) infection and FHB. Resistance to FHB and tolerance of BYDV are quantitative traits that interact. BYD increases both the direct losses from FHB and the production of mycotoxins. Selection under virus pressure, therefore, helps identify those individuals which express FHB resistance more effectively. Moreover, the correlates of virus tolerance (physiological efficiency, generalized stress tolerance and yield) point to those plants with better root traits, ability to produce biomass and yield stability. Together with numerous secondary criteria, such selection eliminates all but a few ‘winners’ in each round. Seen from a systemic perspective, the difficulty of identifying good progeny among descendants of crosses with Sumai 3 does not surprise. Deleterious linkages, pleiotropy and epistasis will usually combine in far from optimal expressions of the assembled genetic information. The systemic approach, by contrast, identifies in repeated cycles increasingly optimized expressions of genes, allowing all potential sources of resistance to be explored. Thus resistant lines can readily be derived from the crosses of susceptible parents, an objective rarely sought in conventional, focused approaches. Moreover, wheat plants respond to the systemic approach’s powerful stresses with enhanced epigenetic variation, raw material from which broader ranges of heritable traits can be selected. Germplasm that expresses a full range of attractive traits while resisting FHB as effectively as Sumai 3 can now be shown to be much more abundant than previously imagined. Perhaps this promise will entice more wheat workers to try a systemic approach...

Surveys of oats in the UK and Nordic countries have identified high concentrations of HT-2 and T-2 can occur in unprocessed oats. HT-2 and T-2 are two closely related type A trichothecenes and two of the most toxic fusarium mycotoxins. There is currently no legislation on HT-2 and T-2, however, there is a discussion limit of 500 µg kg-1 in unprocessed oats. A previous survey identified that variety, previous crop, cultivation, fungicide use and some other factor(s) within organic oat production, which was not within the model, were all significant agronomic factors in the determination of HT-2 and T-2 concentrations of UK oats. Possible agronomy within conventional compared to organic agriculture would include the use of inorganic fertilisers and plant growth regulators (PGR). Oats harvested from two series of agronomic field experiments were analysed for the combined concentration of HT-2 and T-2 (HT2+T2) using ELISA. Experiments were repeated for both winter and spring varieties over two years. The first experiments were of a factorial design with three varieties, three nitrogen rates and plus/minus a PGR (chlormequat). The second series had twelve fungicide regimes. The results identified that there were no significant differences in HT-2+T-2 between samples from oat plots that received different rates of inorganic nitrogen, a PGR, or a range of different fungicide regimes. There was however a significant difference between varieties for both winter and spring variety experiments...

Red ear rot of maize is an important disease in Europe caused by toxigenic Fusarium species like F. graminearum and F. culmorum. To get detailed information about the pathogenesis of the disease and the Fusarium toxin production in infected ears a field study was conducted with maize which was artificially inoculated with F. culmorum at the stage of female flowering. Every fortnight after inoculation, maize ears of two varieties were harvested and analysed for the progress of visual signs of the disease and related Fusarium toxin contamination. During the last harvest in mid October, external infection symptoms showing some small pale or brown-marbled kernels with dark brown rachillae were only observed at the ear tip, whereas internal symptoms visible within the rachis were much more pronounced and showed greyish –brownish or pink discolouration of the pith. The symptoms observed in rachis and kernels corresponded with the toxin contamination showing considerably higher concentrations in the rachis compared to the kernels and a top-down gradient from high to low toxin levels within the ear. This suggests that F. culmorum first infects the rachis from the tip towards the bottom, as it subsequently does the kernels via the rachillae connected to the rachis. As infection symptoms and mycotoxin production were much more pronounced in the rachis than in the kernels, red ear rot evaluation should be improved by observing signs of the disease in both kernels and the rachis...

Although it is generally agreed that most Fusarium head blight infection takes place during the wheat flowering period, very rainy conditions at the end of the plant growth, such as occurred in France in 2007, raise the question of the possibility of late infections on the development of the disease and the production of toxins. Such infections are not taken into account by predictive models. To explore the effect of infection time on disease severity, Fusarium-damaged kernels (FDK), desoxynivalenol (DON) and zearalenone (ZON), an experiment was set up in 2009 on two varieties. The experiment had a split-plot design. Plots were inoculated by spraying Fusarium graminearum conidia at different stage, from heading to ripening. Inoculation time had a significant effect on disease severity, FDK, DON and ZON levels (P<0.0001), as well as interaction between variety and inoculation time. The results of this trial have shown no significant difference between infection at heading, anthesis and post-anthesis until 15 days for disease severity, FDK and mycotoxins levels. Nevertheless, this trial has suggested different behaviour between the two varieties according to infection time and toxin accumulation. The period of high susceptibility to Fusarium graminearum has appeared unstable between varieties, ranging from closed to flowering to a large period from heading to several days after flowering...

Pathogenicity and aggressiveness vs. wheat of 30 new Fusarium accessions, primarily F. graminearum, obtained from random naturally infected grain samples of bread wheat, durum wheat and triticale collected across Romania, phenotypically and by molecular tools has been investigated. A large variation of this trait, expressed as reduction of coleoptiles length (% of control), in seedling stage, on average over three varieties, ranging from 2.1 to 30.9 % was registered. Point field inoculations at anthesis of 90 Fusarium isolate x wheat varieties combinations, revealed also the variability of several components of aggressiveness: severity (14.4-64.8%), AUDPC (104.9-527.1), and FDK 8.1-43.7%, respectively. Molecular techniques allowed identification of Fusarium species and the analysis of polymorphism within fungal isolates. Moreover, the presence of TRI 5 gene involved in DON biosynthesis was detected in the majority of isolates. Similarity between records obtained in seedling and adult stage for the most aggressive of Fusarium isolates, suggests that phenotypic selection in conjunction with molecular tools could be a reliable method to select the appropriate pathogen strains for breeding of resistance...

For breeding purposes, use of reliable Fusarium isolates and inoculation techniques for assessment of host resistance are key components for developing strategies to mitigate the risks caused by this pathogen in maize. Results of evaluating aggressiveness of Fusarium accessions obtained in 2008 from five locations from South Romania, under both seedling and field artificial inoculation in 2009, in terms of coleoptile length (% of control), visual score (1-9) and fumonisin content (FUM, ppm), are reported. High aggressive potential was found in all populations regardless of their geographic origin. Mean percentage values of coleoptile length across three maize hybrids inoculated with 30 Fusarium verticillioides isolates collected in 2008 (six/per location) and two types of culture media, ranged in seedling stage from 15.8 (Braila) to 19.7 (Valul lui Traian). A large variability in accumulation of FUM in grains corresponding to 26 maize genotype x Fusarium isolate combinations averaged over two culture media, was found in 2009 inoculated experiment. A significant close negative correlation between visual score and FUM content was found when 61 maize genotypes have been inoculated with FUN 640-1-2/2006 isolate in 2008...

Fusarium is a large fungal genus, but scientists who work with it continue to search for new species to help bridge perceived phylogenetic gaps and to assess the biogeography of species origin and distribution. Potential new sources for species include collections made from plants and soil in native ecosystems and subsistence agriculture farms. These ecosystems are less likely to have suffered anthropomorphic changes and may offer the best hope for identifying previously undescribed species and for obtaining reliable data on species distribution. In addition to new collections, new species also may result from the break-up of a number of large species complexes that are held together primarily by morphological similarities. The two approaches are complementary and should collectively help to increase the number, diversity and quality of the species known within the genus...

Grain samples of two maize hybrids, medium early (ZP434) and late maturity (ZP704), collected during harvest in 2008 were investigated for contamination by fungi. Grains were plated on agar media and grown fungi were identified by morphological macroscopic and microscopic characteristics on potato-dextrose agar (PDA) and synthetic nutrient agar (SNA). Species of the genus Fusarium were the most common in both hybrids, and their presence amounted to 33.89% (ZP434) and 42.00% (ZP704). Other fungi of genera, Acremonium, Alternaria, Aspergillus, Chaetomium, Cladosporium, Nigrospora, Penicillium, Rhizopus and Trichotecium, were isolated from 0 to 41.00%. Four species belonging to the genus Fusarium were identified, of which the species F. verticillioides was the most common with 28.63% in ZP434 and 30.50% in ZP704 hybrids. The presence of F. graminearum, F. proliferatum and F. subglutinans ranged from 3.00% (ZP704) to 5.00% (ZP434), 0.13% (ZP434) to 7.00% (ZP704) and 0.13% (ZP434) to 7.00% (ZP704), respectively. Generally, the incidence of every particular fungus was higher in the late maize hybrid with a higher moisture content than in the medium-early hybrid with a lower moisture content...

Oilseeds are a perfect medium for microfungi spread and mycotoxin production. With increasing demand for oil crop produce such research has gained a special relevance since research evidence on this issue is scarce. During 2007-2009, prevalent fungi genera, including Fusarium genus, potential producer of deoxynivalenol (DON), zearalenone (ZEA), T-2 toxin (T-2) etc. were determined in our tests. The ELISA immunoenzymatic method and Veratox Fast kits were used to identify and quantify mycotoxins, while Fusarium fungi species were identified using conventional fungi determination techniques. Higher Fusarium fungi contamination level was found on linseed compared with that on spring or winter rapeseed. The difference was even more obvious in different experimental years, however, having identified Fusarium species, F. avenaceum and F. oxysporum were found to be prevalent in the seed of all crop species tested. In 2009, spring rape samples were found to contain F. dimerum which is a significant human pathogen.The presence of DON was identified in 18.2-100%, ZEA in 40 -100%, and T-2 toxin in 100% of seed samples of all oil crop species tested. From the food safety viewpoint, the concentrations determined did not exceed the levels hazardous for health, laid out in the EU regulations, however, the effect of low toxin concentrations is slow and the negative consequences manifest themselves only after some time and in various forms, which poses a serious health risk for humans and animals...

Ears of winter wheat cultivars (Bogatka and Legenda) grown under conventional and ecological (organic) farming systems, were sampled at different developmental stages and examined for their colonization by filamentous fungi, including Fusarium spp. Ears samples were shaken in sterile water containing 0.01% of Tween 80 and appropriate 10-fold dilutions of the initial suspension were inoculated onto agar medium containing antibiotics to inhibit bacterial contaminants. After 6-7 days of incubation at 28o C fungal colonies were counted and after further 4 days fragments of colonies were transferred onto other media for identification. On ears at flowering no Fusarium species were found in 2008 with dry and hot July, but in 2009 with more frequent rainfalls in July Fusarium poae, F. tricinctum and F. avenaceum were detected on winter wheat ears at the flowering stage. At the hard kernel stage the following species were isolated from winter wheat ears: F. poae and F. sporotrichioides in 2008 (17 and 18 isolates respectively) and F. avenacum, F. crookwellense, F. poae, F. sporotrichioides and F. tricinctum in 2009 (2, 18, 39, 2 and 17 isolates respectively, and 9 unidentified Fusarium). In 2008 more Fusarium spp. were found on winter wheat ears grown under the conventional system than under the ecological (organic) system. In the ecological system wheat stands are thinner but taller (due to the lack of any mineral fertilizers and plant growth regulators) and in consequence winter wheat ears in this system may keep moisture shorter than those in the conventional system. It seems that this difference may be the most important factor influencing colonization of winter wheat ears by Fusarium spp. and other fungi under the compared farming systems...

Fusarium head blight resistance (FHB) can be achieved by using improved adapted varieties as crossing partners or by a marker-assisted introgression of mapped QTL from non-adapted sources. In this long-term study Fhb1 on chromosome 3BS and Qfhs.ifa-5A located on chromosome 5A were introgressed into European elite spring and winter wheat to test effects on FHB resistance and side effects on agronomic performance and F. graminearum isolates and mixtures. The introgression of the QTL Fhb1 and Qfhs.ifa-5A from the Sumai 3-descendant CM82036 could be performed in the shortest possible way by marker-assisted backcrossing. They were both validated in European elite wheat background. Effects on FHB resistance were, on average, only about half of the effect in the original mapping populations. In the best phenotypically and marker-selected BC0 line of spring wheat FHB was reduced from 40 to 4.3% of disease symptoms by introgressing both QTL, in the best BC3 line of winter wheat the reduction was 28 and 37% for the moderately resistant and highly susceptible recurrent parent, respectively. Introgression of both QTL simultaneously did not result in significantly higher FHB resistance than introgression of only one of both QTL. Small significant negative effects on grain yield were detected in the Anthus but not in the Opus BC3F2:5 backcross population when both QTL were introgressed. Backcrossing with only Qfhs.ifa-5A did not reduce grain yield significantly. Differences in heading date, plant height and quality traits were in all cases small although often significant. Selection of lines with improved resistance level and similar high yield level like the recurrent parent was feasible. Stability of FHB resistance mediated by both QTL was stable across 22 Fusarium isolates from Europe and Canada and six binary mixtures. Competition effects between isolates in mixtures were obvious but could not be attributed to the resistance of the host. In conclusion, marker-based backcrossing is a feasible option for introgressing Fhb1 or Qfhs.ifa-5A QTL into the high-yielding, quality-oriented European wheat gene pool...

Combining ability analysis and heterosis for cotton fiber quality traits were studied in a set of diallel crosses involving eight cotton (Gossypium sp.) genotypes. Randomized complete block design was used to test 56 F1 and 8 parents for fiber quality traits; length (Len), strength (Str), micronaire (Mic), uniformity (Unf), elongation (Elg), spinning consistency index (Sci) and short fiber index (Sfi). Analysis revealed significant general combining ability (GCA) and specific combining ability (SCA) effects for all the traits and additive gene effects were important in the inheritance of the traits. Giza-45 had the highest GCA effects for Len, Sci, Unf and Elg while Is-4 had the highest Str value. Mic and Sfi values were lowest for Askabat-100 and Giza-45, respectively. The cross Cukurova-1518 × 108-F and Nazilli-84S × Askabat-100 had the lowest SCA effects for Mic and Sfi, respectively. The highest values for Len (Askabat-100 × 108-F), for Str (Acala Prema × 108-F), for Sci (Is-4 × Giza-45), for Unf (Stoneville-453 × Askabat-100) and for Elg (108-F × Is-4) were also obtained. Hybridizations among Askabat-100 × Nazilli-84S, Is-4 × Giza-45, Askabat-100 × Stoneville-453, Askabat-100 × Giza-45, Is-4 × 108F, Giza-45 × 108F, Giza-45 × Acala Prema, Nazilli-84S × Giza-45, Is-4 × Nazilli-84S and Acala Prema × Askabat-100 crosses yielded the best heterosis and heterobeltiosis values. Aforementioned parents and crosses could be utilized for further selection of high fiber quality and applying 3-way crosses or modified backcross or recurrent selection to genotypes having good combining ability would improve fiber quality...

Genetic resistance against Pythium species would be an efficient control of this major seed and seedling fungal pathogen in safflower (Carthamus tinctorius), but so far no source has been identified. Therefore, identifying and then incorporating genetic resistance into the cultivars would be an ideal method of control for this disease. So in this study the resistance to seed rot and damping-off caused by Pythium ultimum among seventeen genotypes of safflower collected from all major production regions of the crop in Iran and some other countries was investigated. Pythium ultimum, previously identified as the most prevalent Pythium isolates on safflower, were used to infest the sterilized soil, which was seeded with safflower genotypes in greenhouse conditions. The experiment was conducted as a split plot design in which sterile and Pythium-infested soils were considered as main plots, and seventeen genotypes of safflower were sub plots. In sterile media, percent of seedling emergence (SES) and in Pythium-infested media, percent of seedling emergence (SEI), percent of diseased seedlings (DSI), percent of uninfected seedlings (USI) and percent of non-emerged seeds (NSI) were recorded. Symptoms showed that in safflower, damping-off occurred in both forms of pre and post emergence. Genotypic variation was existed for level of susceptibility to P. ultimum. Significant differences in SES and SEI were detected among safflower genotypes (P < 0.01), and a significant correlation between SES and seed weight (P < 0.05); SES with SEI (P < 0.05) were detected. Result showed that between evaluated genotypes there wasn’t any genotype with complete resistance (100%) to P. ultimum, so the susceptibilities were assayed. Based on the assessed variables, genotypes LRV-55-295, Aceteria, PI-250537 and IL-111 appear to be highly susceptible to the Pythium infection, whereas 34040, Arak281, and Isfahan were the least susceptible to the disease. Further research will be conducted to determine whether the resistance detected in these genotypes is heritable...

The objective of the present study was to determine the extent and pattern of genotypic diversity for six spike quantitative characters and two other traits in 36 winter triticale cultivars released in Poland, to classify the cultivars into similarity groups (clusters) and to identify those traits, among the studied ones, which mostly discriminated distinguished groups of cultivars. The 36 cultivars, released in the period from 1982 to 1999, were evaluated across three years 2002-2004 at the Experimental Field Station in Czesławice near Nałęczów, Poland. The experiments were carried out on the brown soil with loess subsoil. In each year the one-replicated experimental design was used with 2 m2 plots, rows 20 cm apart, and dense sowing using about 2 cm spacing of seeds. Analyses of variance for each trait data according to the random model (both cultivars and years were assumed to be random factors) were done. To classify and characterize genotypic diversity of the cultivars for the eight traits, the pattern analysis was used. It involved both cluster analysis using Ward’s procedure with a measure of the multivariate similarity among cultivars being Squared Euclidean Distance and canonical variate analysis (CVA) on the basis of cultivar BLUPs for the original traits. Quite different groups of cultivars for the studied traits were found, specially one group was substantially distanced to the others. As it was shown by CVA, spike length and number of spikelets per spike as negatively correlated with number of grains per spikelet in the studied set of the cultivars relatively largest contributed to overall differentiation of the distinguished eight groups and then, these traits best discriminated among the eight cultivar groups in the term of Mahalanobis distance for the considered traits. The 1000 grain weight and grain protein content much less contributed to overall discrimination of the cultivar groups than the previous four traits. The most important agronomic traits characterizing productivity of the spike grain weight and its two components, e.g. number of grains per spikelet and number of grains per spike had least discriminating power for the groups of cultivars. Grain yield per unit area of cereals is a result of spike grain yield and the number of spikes per unit area. In these studies of winter triticale cultivar diversity only grain spike yield and its components were included. Thus, the presented study are a primary evaluating of phenotypic diversity in the cultivars. The further study on the cultivar diversity evaluation for grain yield per unit area and its components is necessary...  

During the recent years traditional tillage techniques and procedures have been successfully used in combination with the modern molecular technologies. This enables the researchers not only to employ more objective methods of parental material selection, but also shortens the time required to breed a new variant. Many researchers tried to surmise the heterosis effect by examining the genetic distance between two parental lines. The main objective of this work was to display the correlation between the heterosis effect among the F1 generation of maize and the genetic distance between the parental components. Furthermore, an attempt was made to predict the future heterosis effect using mathematical functions. Finding a proof of those correlations would make it possible to select the parental material, used to create a new variation, more effectively and thus to reduce the number of lines tested during the experiment. Hence it would reduce the time needed for the experiments and also significantly reduce the overall cost of the research project. The research displayed that the molecular markers AFLP and RAPD are useful for predicting the formula of a new corn hybrid . They can be also used to group lines according to their origin or parentage, including those having incomplete information about their parentage. For both markers: RAPD and AFLP, the functions that best describe the correlation between the heterosis effect and the genetic distance, were: a third degree polynomial y=a+bx+cx2+dx3 and a linear function y = a + bx...

A genetic model is developed with additive, dominance and genotype × environment interaction effects for the progeny from a diallel mating design. To uncover the genetic contributions of some traits of rapeseed to seed yield and find indicator traits for indirect selection, multivariable conditional analysis was conducted based on this method. Therefore, an experiment was conducted to estimate genetic parameters using a half diallel of nine international rapeseed cultivars. The 36 F1 hybrids, the parents and four additional cultivars were planted in the breeding nurseries in 2008 and 2009. Several traits including number of pods per plant (NPP), pod length (LP), height of the first pod (HFP), height of the first lateral branch (HFB), stem diameter (SD), days of flowering period (FP), days to physiological maturity (DPM) and seed yield were recorded. The genetic variance component (VD×Y) was significant for all the studied traits but the genetic variance component (VA) was significant for NPP, HFB, HFP, DPM and SY traits and the genetic variance component (VD) was significant for HFB, HFP, LP and FP traits. There was significant positive phenotypic correlation (rA) between seed yield with NPP and HFP and there was significant positive dominance × year interaction correlation (rD×Y) between seed yield with NPP and DPM while there was significant negative dominance × year interaction correlation (rD×Y) between seed yield with HFB, LP and FP. There were significantly positive additive effects of SY for two parents Orient and Talaye. Finally according to additive-dominance genetic model and conditional genetic effects, the genotypes Talaye proved good general combiner for seed yield improvement and crosses 4 × 8 (Orient × Talaye), 7 × 8 (Opera × Talaye) were found the best specific combiner for all the studied traits...

The Mexican oregano Lippia berlandieri Schauer is widespread in Mexico. Several studies have involved the characterization of its essential oil in order to use it as food additive and for medical aims, as well as its antimicrobial and antioxidant capacity, although there is a lack of information about genetic diversity of this species. In order to increase Lippia berlandieri Schauer application, knowledge of the genetic characteristics of the species and creation of a program for germplasm conservation seem to be essential. This study was carrying out in order to understand the population genetics of Lippia berlandieri Schauer. Oregano seeds were collected from 8 locations of the Chihuahua Southeastern desert area. The results showed high genetic variability among oregano populations suggesting that this species is mainly allogamous, pollinated mainly by insects because of the attractive flower color; AMOVA showed genetic differences within and among populations, the last one was found approximately 5 times higher than the genetic differences within populations. The analysis of the Wright´s statistics, especifically FIS, supported the hypothesis that plants are not self-pollinating. On the other hand, it was found that the number of plants per a sample recommended for further genetic analysis of this specie is 13 or more...

The Mexican oregano Lippia berlandieri Schauer is widespread in Mexico. Several studies have involved the characterization of its essential oil in order to use it as food additive and for medical aims, as well as its antimicrobial and antioxidant capacity, although there is a lack of information about genetic diversity of this species. In order to increase Lippia berlandieri Schauer application, knowledge of the genetic characteristics of the species and creation of a program for germplasm conservation seem to be essential. This study was carrying out in order to understand the population genetics of Lippia berlandieri Schauer. Oregano seeds were collected from 8 locations of the Chihuahua Southeastern desert area. The results showed high genetic variability among oregano populations suggesting that this species is mainly allogamous, pollinated mainly by insects because of the attractive flower color; AMOVA showed genetic differences within and among populations, the last one was found approximately 5 times higher than the genetic differences within populations. The analysis of the Wright´s statistics, especifically FIS, supported the hypothesis that plants are not self-pollinating. On the other hand, it was found that the number of plants per a sample recommended for further genetic analysis of this specie is 13 or more...

In the research carried out in the years 1999-2001 the following characteristics of three edible potato cultivars were determined: tuber yield, starch content, dry matter content, vitamin C content and starch yield. Genotype-environment interaction for the above characteristics was evaluated on the basis of main effects (genotypes and years) and interaction effects by means of the variance analysis for repeated experiments and according to the linear model for the design which confounds the type 33 interaction. Moreover, there were calculated the variance of genotype stability describing the environmental variation of the genotypes, and the ecovalence coefficient which describes the genotype x environment interaction. All the analysed characteristics were influenced by the cultivars (genotypes) and the environment. The genotype-environment interaction reflecting different response of the cultivars to changeable environmental conditions proved to be significant for all the examined characteristics. The analysis of results does not allow to unambiguously indicate the stabile genotype because the Muza cultivar was most stable for vitamin C and dry matter contents, and starch yield whereas Aster and Ania proved to be most stable as far as tuber yield and starch content, respectively, were concerned...

Forty eight inbred lines of winter rye, of various origin and pedigree, were analysed using 19 RAPD (random amplified polymorphic DNA) primers, 8 ISSR (inter-simple sequence repeats) primers and 13 SSR (simple sequence repeats) primer pairs. On the basis of particular marker types, there were created three separate dendrograms and one combined similarity tree, prepared on account of the whole data. Correlation coefficients for individual technique based on genetic similarity matrices were not significant. By comparing the GS data obtained on the basis of singular methods with collective matrix, it was observed that the highest correlation rate was for ISSR method (r=0.68). The utility of each marker technique was compared by using marker index MI. Diversity detecting index (DDI) was suggested in the paper, which may prove helpful in planning and comparing researches on phenetic relationships...

The experimental material consisted of 15 winter wheat cultivars (14 Polish-bred cultivars and one British cultivar) representing the results of over 100 years of breeding. The cultivars were tested in two-factor field experiments (cultivars were one factor and nitrogen fertilization rates, the other factor) carried out in split-plot design across two consecutive years. This paper demonstrates a combined using AMMI and cluster analyses for effective and efficient estimate of grain-yield response to investigated environments (combinations of 2 years × 3 nitrogen fertilization rates). First, homogenous groups of cultivars were identified in terms of their genotypic profile of AMMI(s) estimates of GEI effects using Ward’s method of cluster analysis. Then, these groups were divided into separate homogenous subgroups with respect to genotype means. The cultivars in each subgroup have a similar grain yield response to the environments and, then, similar adaptation pattern, although the genotype groups differed in adaptation to these environments...

The distribution of Chrysanthemum segetum L. in Poland, based on a field research, herbarium materials, literature and unpublished data, is described with a list of localities. Altogether, 352 localities (210 ATPOL squares) for this species have been identified. Most localites are concentrated in North and West parts of Poland...

Cereals are important crops all over the world. Cereals are grown on a quarter of cultivated land in Hungary. Cereals are competitive and thus they play a significant role in ecological farming. The most important species in the Hungarian ecological farms are winter wheat and spelt. Weed floras in ecological farming systems are different from those in conventional cropping systems. These differences are due to different cropping practices, including weed control and fertilization methods.Our goal was to determine how farming systems affected the weed flora. A 2500 ha ecological farm and a neighbouring conventional farm in south-eastern Hungary were surveyed four times during the season in 2007 and 2008. Effects of farming systems were assessed for weed cover, number of species, and Shannon’s diversity index.The ecological farm showed higher weed-cover than conventional farm. The differences were rather high in the inner areas and on the margins, too. Farming systems same differed in values of number of species. More species were found in ecological farm. The Shannon diversity showed significant difference only in the inner areas. The diversity of margins were similar...

It is prudent to conserve communities which are as species-rich as possible. This is the only means of ensuring that species diversity but also gene diversity is high enough to allow for the necessary adaptations to changed environmental conditions. Arable plant communities are a special case here because losses in the last 5 decades have been particularly severe. Numerous studies from Central Europe reported dramatic declines of the segetal flora.In most of the federal states of Germany, successful measures for protecting the segetal flora, such as the establishment of field flora reserves and field margin strip programmes have often unfortunately come to a halt due to changes in funding, lack of regional support or high levels of bureaucracy. The new project "100 fields for biodiversity", which has been funded by the Deutsche Bundesstiftung Umwelt (DBU) since 2007, aims to establish a network of protected areas for the preservation of endangered segetal species in Germany. Management aimed at preserving and fostering arable wild plants is to be guaranteed in the long term on at least 100 particularly suitable arable sites...

The results of a research on segetal weed communities in fibre flax in Poland are presented, with respect to different regions of cultivation, and changes in the level of infestation during the past forty years. Observations on composition and abundance of weed infestations were made in fields in six experimental farms at the Institute of Natural Fibres and Medicinal Plants. The observations conducted in the period 1967-2008 did not show the occurrence of weed species from the group of so-called “flax specialists”: Lolium remotum Schrank, Spergula arvensis L. subsp. maxima (Weiche) O. Schwarz, Camelina alyssum (Mill.) Thell. and Cuscuta epilinum Weihe Ex Boenn. In Poland, weed populations in fibre flax consist of species typical for cereals and root crops: Chenopodium album L., Polygonum convolvulus L., Viola arvensis Murr., Stellaria media Vill., Lamium amplexicaule L., Thlaspi arvense L., Elymus repens (L.) Gould. and Polygonum nodosum Pers...  

The medicinal usage of silverweed herb (Anserinae herba) is primarily related to the presence of phenolic compounds. Three populations of silverweed (Potentilla anserina L.) occurring at the edges of arable fields in Podlasie area (north-eastern Poland) were compared in respect of the content and composition of phenolics. Herb collected from the investigated populations differed in the content of determined compounds. The tannin content was very low (0.81-0.91%). The total flavonoid content ranged from 0.48 to 0.60%. Phenolic acid content was much higher (1.38-2.26%). Three flavan-3-ols: (+)-catechin, (-)-epicatechin, and (-)-epigallocatechin, four flavonol glycosides: rutoside, quercetin-3-O-glucoside, isorhamnetin-3-O-glucoside, and kaempferol-3-O-glucoside, as well as one phenolic acid (ellagic acid) were identified as a_result of HPLC analysis of methanolic extracts from the investigated raw materials. The most considerable differences between populations concerned the content of (+)-catechin (87.0-199.3 mg × 100 g-1), (-)-epigallocatechin (141.9-290.6 mg × 100 g-1), and rutoside (192.3-386.0 mg × 100 g-1) in herb...

We evaluated the effect of plant litter species diversity on the on humus accumulation in the underlying substratum and on soil microbial communities composition in experimental field study.. Sandy loam (sand mixed with loam) mesocosms of were examined over the course of 2.5 years. Plots contained simplified substratum –. Five litters composed of meadow plants; both grasses and herbs (weed species) were used. Litters were composed of single species (I - Dactylis glomerata, II - Festuca rubra and III - Trifolium pratense) or were species mixtures IV (mixture of 3 species I, II and III); V (mixture of 12 species - IV and 9 other grasses and meadow weeds). Results baased mainly on the last year of the experiment show that most of the differences among treatments found in the substratum below the litter cover resulted from the litter diversity. Soil respiration, microbial biomass and numbers of fungi and bacteria did not differentiate between mono- and multispecies treatments. Despite of that the soil respiration and algal biomass were significantly correlated during the study period. The biomass of algae as well as carbon and nitrogen increases in the substratum, depended on the litter diversity and were higher when litter composition was more complicated. In general, our results suggest that algae may participate in the process of humus formation...