Differences in susceptibility of winter wheat varieties for Fusarium species under Belgian growing conditions

Fusarium head blight is an important disease of cereal crops caused by Fusarium species. It causes not only a reduction in yield, but most Fusarium species (F. graminearum. F. culmorum, F. avenaceum. F. poae) produce also a range of toxic metabolites such as deoxynivalenol (DON) and zearalenone (ZEA). The evaluation of Fusarium species was followed up under natural infection conditions during the growing seasons 2001--2002 and 2002--2003 in two varietal winter wheat experiments on the experimental farm of the Hogeschool Gent at Bottelare. Disease pressure, DON and ZEA content, different Fusarium species as well as growth and yield parameters were determined. In both years there were significant differences between the varieties concerning the susceptibility to Fusarium and the DON content. ZEA was not found in the kernels. The mean deoxynivalenol (DON) content was in 2002 (1,126 mg/kg) higher than in 2003 (0.879 mg/kg) although the mean disease severity was bigger in 2003 than in 2002 what means that the DON content was not always correlated with the disease severity. The Fusarium species most frequently identified in our two field trials (Bottelare) were F. graminearum and F. culmorum Varietal differences in susceptibility to Fusarium species and DON contamination could be detected.     

Toxigenic Fusarium species infecting wheat heads in Poland

Toxigenic Fusarium species are common pathogens of wheat and other cereals worldwide. In total, 449 wheat heads from six localities in Poland, heavily infected with Fusarium during 2009 season, were examined for Fusarium species identification. F. culmorum was the most common species (72.1% on average) with F. graminearum and F. avenaceum the next most commonly observed, but much less frequent (13.4 and 12.5% respectively). F. cerealis was found in 1.8% of all samples, and F. tricinctum was found only in one sample (0.2%). Subsequent quantification of the three major mycotoxins (deoxynivalenol, zearalenone and moniliformin) in grain and chaff fractions with respect to associated prevailing pathogen species uncovered the following patterns. Moniliformin (MON) was found in low amounts in all samples with F. avenaceum present. In contrast, deoxynivalenol (DON) and zearalenone (ZEA) were the contaminants of F. culmorum- and F. graminearum-infected heads. The highest concentration of DON was recorded in grain sample collected in Radzików (77 µg g^?1). High temperatures in Central Poland during July and August accompanied with high rainfall in July were responsible for this high DON accumulation. Trichothecene, zearalenone, enniatin and beauvericin chemotypes were identified among 21 purified isolates using gene-specific PCR markers.     

Quantification of trichothecene-producing Fusarium species in harvested grain by competitive PCR to determine efficacies of fungicides against Fusarium head blight of winter wheat

We developed a PCR-based assay to quantify trichothecene-producing Fusarium based on primers derived from the trichodiene synthase gene (Tri5). The primers were tested against a range of fusarium head blight (FHB) (also known as scab) pathogens and found to amplify specifically a 260-bp product from 25 isolates belonging to six trichothecene-producing Fusarium species. Amounts of the trichothecene-producing Fusarium and the trichothecene mycotoxin deoxynivalenol (DON) in harvested grain from a field trial designed to test the efficacies of the fungicides metconazole, azoxystrobin, and tebuconazole to control FHB were quantified. No correlation was found between FHB severity and DON in harvested grain, but a good correlation existed between the amount of trichothecene-producing Fusarium and DON present within grain. Azoxystrobin did not affect levels of trichothecene-producing Fusarium compared with those of untreated controls. Metconazole and tebuconazole significantly reduced the amount of trichothecene-producing Fusarium in harvested grain. We hypothesize that the fungicides affected the relationship between FHB severity and the amount of DON in harvested grain by altering the proportion of trichothecene-producing Fusarium within the FHB disease complex and not by altering the rate of DON production. The Tri5 quantitative PCR assay will aid research directed towards reducing amounts of trichothecene mycotoxins in food and animal feed.     

Inheritance of Fusarium head blight resistance in the soft red winter wheat Ernie

Fusarium head blight (FHB), caused by Fusarium graminearum Schwabe [telomorph:Gibberella zeae Schw. (Petch)], is an increasingly important disease of wheat (Triticum aestivum L.). Host-plant resistance is considered to be the most economical means of control, but a lack of unique sources of resistance has hindered efforts to breed resistant varieties. The soft red winter wheat, Ernie, has moderately high FHB resistance and is widely used in U.S. breeding programs; however, the genetics of resistance have not been studied. The objectives of this study were to estimate the genetic effects, gene numbers, and heritability for traits related to FHB resistance in Ernie through generation means analyses and variance analyses of 243 F₃-derived F₈ and F₉ recombinant inbred lines (RILs). Replicated experiments were grown in the greenhouse, inoculated with F. graminearum, and evaluated for disease spread and the FHB index (FHBI). The latter was calculated as the percentage of diseased spikelets in inoculated spikes and is often referred to as type-II resistance. Gene action for both disease spread and FHBI was primarily additive with partial dominance for low disease. Broad-sense heritabilities for spread and FHBI were 78.2% and 78.3%, respectively, while the narrow-sense heritabilities were 51.3% and 55.4%, respectively. Line-mean heritabilities from analyses of variance of RILs were 0.70 and 0.87 for spread and FHBI, respectively. A minimum of four genes conditioned both disease spread and FHBI. These results suggest that breeders should be able to enhance FHB resistance by combining the resistance in Ernie with other complementary additive sources of resistance.     

Deoxynivalenol and 3-acetyldeoxynivalenol and Fusarium species in winter triticale

Fusarium species infecting heads of Triticale and mycotoxins presence in infected kernels and chaff were studied during two seasons. The most important species observed on infected heads were in 1986F. avenaceum (39%),F. nivale (21%),F. culmorum (20%),F. graminearum (14%), and others (6%). In 1987 after long and snowy winterF. nivale dominated (64%), followed byF. avenaceum (24%),F. culmorum (6%), andF. graminearum (5%). The mycotoxins deoxynivalenol (DON) and 3-acetyl DON were present in all 11 subsamples of kernels from heads infected byF. culmorum and/orF. Graminearum (1.6–16.4 mg and 0.7–2.4mg/kg, respectively). Chaff from the same subsamples contained 9.9–33.2mg/kg of DON and 5.2–16.0mg/kg of 3-AcDON. Kernels with visibleFusarium-damage contained 2.4–31.2 mg/kg of DON and 1.2–6.0 mg/kg of 3-AcDON. Remaining part of kernels without symptoms of visibleFusarium-damage contained only DON in an amount of 0.9–5.9 mg/kg.     

Association mapping for Fusarium head blight resistance in European soft winter wheat

Resistance to Fusarium head blight (FHB) is of great importance in wheat breeding programs in the northern hemisphere. In Europe, breeders prefer adapted germplasm as resistance donor because of high grain yield and quality demands. Our objective was to identify chromosomal regions affecting FHB resistance among 455 European soft winter wheat (Triticum aestivum L.) lines using a genome-wide association mapping approach and to analyze the importance of epistatic interactions. All entries were evaluated for FHB resistance by inoculation in two environments and several ratings. Wheat was genotyped by 115 simple sequence repeat markers randomly distributed across the genome and two allele-specific markers for Rht-B1 and Rht-D1 genes. The genome-wide scan revealed nine significant (P < 0.05) marker–phenotype associations on seven chromosomes including dwarfing gene Rht-D1. Using a Bonferroni–Holm correction, three significant associations remained on chromosomes 1B, 1D, and 2D. The proportion of the genotypic variance explained simultaneously by individual markers was 36% and increased to 50% when two digenic epistatic interactions were considered, one of them associated with Rht-B1. In conclusion, new genomic regions on chromosomes 1D and 3A could be found for FHB resistance in European wheat and the effect of epistatic interactions was substantial.     

Evaluation of genetic diversity of Fusarium head blight resistance in European winter wheat

Genetic diversity in relation to Fusarium head blight (FHB) resistance was investigated among 295 European winter wheat cultivars and advanced breeding lines using 47 wheat SSR markers. Twelve additional wheat lines with known FHB resistance were included as reference material. At least one SSR marker per chromosome arm, including SSR markers reported in the literature with putative associations with QTLs for FHB resistance, were assayed to give an even distribution of SSR markers across the wheat genome. A total of 404 SSR alleles were detected. The number of alleles per locus ranged from 2 to 21, with an average of 8.6 alleles. The polymorphism information content of the SSR markers ranged from 0.13 (Xwmc483) to 0.87 (Xwmc607), with an average of 0.54. Cluster analysis was performed by both genetic distance-based and model-based methods. In general, the dendrogram based on unweighted pair-group method with arithmetic averages showed similar groupings to the model-based analysis. Seven clusters were identified by the model-based method, which did not strictly correspond to geographical origin. The FHB resistance level of the wheat lines was evaluated in field trials conducted over multiple years or locations by assessing the following traits: % FHB severity, % FHB incidence, % diseased kernels, in spray inoculation trials, and % FHB spread and % wilted tips, in point inoculation trials. Association analysis between SSR markers and the FHB disease traits detected markers significantly associated with FHB resistance, including some that have not been previously reported. The percentage of variance explained by each individual marker was, however, rather low. Haplotype analysis revealed that the FHB-resistant European wheat lines do not contain the 3BS locus derived from Sumai 3. The information generated in this study will assist in the selection of parental lines in order to increase the efficiency of breeding efforts for FHB resistance.     

QTL associated with Fusarium head blight resistance in the soft red winter wheat Ernie

Fusarium head blight (FHB), mainly caused by Fusarium graminearum Schwabe [telomorph: Gibberella zeae Schw. (Petch)], is an increasingly important disease of wheat (Triticum aestivum L.). Host-plant resistance provides the best hope for reducing economic losses associated with FHB, but new sources of resistance are limited. The moderately resistant winter wheat cultivar, Ernie, may provide a source of resistance that differs from Sumai 3 but these genes have not been mapped. Also hindering resistance breeding may be associations of resistance with agronomic traits such as late maturity that may be undesirable in some production environments. This research was conducted to identify QTL associated with type II FHB resistance (FHB severity, FHBS), and to determine if they are associated with days to anthesis (DTA), number of spikelets (NOS), and the presence/absence of awns. Two hundred and forty-three F₈ recombinant inbred lines from a cross between the resistant cultivar, Ernie and susceptible parent, MO 94-317 were phenotyped for type II FHB resistance using point inoculation in the greenhouse during 2002 and 2003. Genetic linkage maps were constructed using 94 simple sequence repeat (SSR) and 146 amplified fragment length polymorphic (AFLP) markers. Over years four QTL regions on chromosomes 2B, 3B, 4BL and 5A were consistently associated with FHB resistance. These QTL explained 43.3% of the phenotypic variation in FHBS. Major QTL conditioning DTA and NOS were identified on chromosome 2D. Neither the QTL associated with DTA and NOS nor the presence/absence of awns were associated with FHB resistance in Ernie. Our results suggest that the FHB resistance in Ernie appears to differ from that in Sumai 3, thus pyramiding the QTL in Ernie with those from Sumai 3 could result in enhanced levels of FHB resistance in wheat.     

Susceptibility of selected winter wheat cultivars produced in Poland to Fusarium head blight

The susceptibility of six winter wheat cultivars toFusarium head blight has beenstudied. The lowest infected plants intensity, mean degree of head damage and fusariosis index exhibited cultivar Grana which also cumulated the lowest amount of trichothecenes (DON and derivatives ). Possibility to produce NIV by Polish strains has been found.in F.graminearum.     

Inheritance of resistance to Fusarium head blight in three European winter wheat populations

Fusarium head blight (FHB) resistance is of particular importance in wheat breeding programmes due to the detrimental effects of this fungal disease on human and animal health, yield and grain quality. Segregation for FHB resistance in three European winter wheat populations enabled the identification of resistance loci in well-adapted germplasm. Populations obtained from crosses of resistant cultivars Apache, History and Romanus with susceptible semi-dwarfs Biscay, Rubens and Pirat, respectively, were mapped and analysed to identify quantitative trait loci (QTL) for FHB severity, ear emergence time and plant height. The results of the present study together with previous studies in UK winter wheat indicated that the semi-dwarfing allele Rht-D1b seems to be the major source for FHB susceptibility in European winter wheat. The high resistance level of the cultivars Romanus and History was conditioned by several minor resistance QTL interacting with the environment and the absence of Rht-D1b. In contrast, the semi-dwarf parents contributed resistance alleles of major effects apparently compensating the negative effects of Rht-D1b on FHB reaction. The moderately resistant cultivar Apache contributed a major QTL on chromosome 6A in a genome region previously shown to carry resistance loci to FHB. A total of 18 genomic regions were repeatedly associated with FHB resistance. The results indicate that common resistance-associated genes or genomic regions are present in European winter wheats.     

Genotype x strain interactions for resistance to Fusarium head blight caused by Fusarium culmorum in winter wheat

Summary In 3 consecutive years, a set of 17 winter wheat genotypes, representing a wide range of Fusarium head blight resistance, was inoculated with four strains of Fusarium culmorum. Fusarium head blight ratings were analyzed. The interaction between genotypes, strains, and years was described using a Finlay-Wilkinson model and an Additive Main effects and Multiplicative Interaction effects (AMMI) model. The interaction consisted primarily of a divergence of genotypical responses with increasing disease pressure, modified by genotype specific reactions in certain years. The divergence was mainly caused by one very pathogenic strain. The Fusarium head blight resistance in this study can be described as horizontal resistance in terms of Vanderplank, with the exception of three genotypes selected from one particular cross that showed a strain-year combination dependent resistance which was ineffective in 1 year.     

Differential drought-induced modulation of ozone tolerance in winter wheat species

Recent reports challenge the widely accepted idea that drought may offer protection against ozone (O(3)) damage in plants. However, little is known about the impact of drought on the magnitude of O(3) tolerance in winter wheat species. Two winter wheat species with contrasting sensitivity to O(3) (O(3) tolerant, primitive wheat, T. turgidum ssp. durum; O(3) sensitive, modern wheat, T. aestivum L. cv. Xiaoyan 22) were exposed to O(3) (83ppb O(3), 7h d(-1)) and/or drought (42% soil water capacity) from flowering to grain maturity to assess drought-induced modulation of O(3) tolerance. Plant responses to stress treatments were assessed by determining in vivo biochemical parameters, gas exchange, chlorophyll a fluorescence, and grain yield. The primitive wheat demonstrated higher O(3) tolerance than the modern species, with the latter exhibiting higher drought tolerance than the former. This suggested that there was no cross-tolerance of the two stresses when applied separately in these species/cultivars of winter wheat. The primitive wheat lost O(3) tolerance, while the modern species showed improved tolerance to O(3) under combined drought and O(3) exposure. This indicated the existence of differential behaviour of the two wheat species between a single stress and the combination of the two stresses. The observed O(3) tolerance in the two wheat species was related to their magnitude of drought tolerance under a combination of drought and O(3) exposure. The results clearly demonstrate that O(3) tolerance of a drought-sensitive winter wheat species can be completely lost under combined drought and O(3) exposure.     

Molecular mapping of Fusarium head blight resistance in the winter wheat population Dream/Lynx

Fusarium head blight (FHB), mainly caused by Fusarium graminearum and F. culmorum, can significantly reduce the grain quality of wheat (Triticum aestivum L.) due to mycotoxin contamination. The objective of this study was to identify quantitative trait loci (QTLs) for FHB resistance in a winter wheat population developed by crossing the resistant German cultivar Dream with the susceptible British cultivar Lynx. A total of 145 recombinant inbred lines (RILs) were evaluated following spray inoculation with a F. culmorum suspension in field trials in 2002 in four environments across Germany. Based on amplified fragment length polymorphism and simple sequence repeat marker data, a 1,734 cM linkage map was established assuming that the majority of the polymorphic parts of the genome were covered. The area under disease progress curve (AUDPC) was calculated based on the visually scored FHB symptoms. The population segregated quantitatively for FHB severity. Composite interval mapping analysis for means across the environments identified four FHB resistance QTLs on chromosomes 6AL, 1B, 2BL and 7BS. Individually the QTLs explained 19%, 12%, 11% and 21% of the phenotypic variance, respectively, and together accounted for 41%. The QTL alleles conferring resistance on 6AL, 2BL and 7BS originated from cv. Dream. The resistance QTL on chromosome 6AL partly overlapped with a QTL for plant height. The FHB resistance QTL on 7BS coincided with a QTL for heading date, but the additive effect on heading date was of minor importance. The resistance QTL on chromosome 1B was associated with the T1BL.1RS wheat-rye translocation of Lynx.     

Seasonal variations of Fusarium species in wheat fields in Upper Egypt

Abstract

Populations of the genus Fusarium in wheat fields were studied within the crop-growing season at Qena area (Upper Egypt) using two different types of media (DCPA and DRBA) at 25°C. Fourteen Fusarium species were isolated during this study, namely F. anthophilum, F. aquaeductuum, F. chlamdosporum, F. dimerum, F. merismoides, F. moniliforme, F. oxysporum, F. poae, F. proliferatum, F. sambucinum, F. scripi, F. solani, F. sporotrichioides and F. subglutinans. Fusarium merismoides, F. oxysporum and F. sambucinum were the most common Fusarium species isolated from different wheat plant parts (rhizosphere and rhizoplane) as well as from the wheat fields (soil and air). Fusarium spp. rarely appeared at the beginning of the season and increased sharply between January to March and decreased slightly or sharply at the end of the season according to the type of media and isolation source.     

Variation in nitrogen use efficiency among soft red winter wheat genotypes

Summary Nitrogen use efficiency (NUE), defined as grain dry weight or grain nitrogen as a function of N supply, was evaluated in 25 soft red winter wheat genotypes for two years at one location. Significant genotypic variation was observed for NUE, nitrogen harvest index, and grain yield. Genotype x environment interaction for these traits was not significant. Several variables including N uptake efficiency (total plant N as a function of N supply), grain harvest index, and N concentration at maturity were evaluated for their role in determining differences in NUE. Nitrogen uptake efficiency accounted for 54% of the genotypic variation in NUE for yield and 72% of the genotypic variation in NUE for protein. A path coefficient analysis revealed that the direct effect of uptake efficiency on NUE was high relative to indirect effects.The investigation reported in this paper (No. 85-3-122) is in connection with a project of the Kentucky Agricultural Experiment Station and is published with approval of the Director     

A major QTL for resistance against Fusarium head blight in European winter wheat

We report on the verification of a resistance quantitative trait locus (QTL) on chromosome 1BL (now designated Qfhs.lfl-1BL) which had been previously identified in the winter wheat cultivar Cansas. For a more precise estimation of the QTL effect and its influence on plant height and heading date lines with a more homogeneous genetic background were created and evaluated in four environments after spray inoculation with Fusarium culmorum. Qfhs.lfl-1BL reduced FHB severity by 42% relative to lines without the resistance allele. This QTL did not influence plant height, but significantly delayed heading date by one day. All of the most resistant genotypes of the verification population carried this major QTL displaying its importance for disease resistance. This resistance QTL has not only been found in the cultivar Cansas, but also in the three European winter wheat cultivars Biscay, History and Pirat. A subsequent meta-analysis confirmed the presence of a single QTL on the long arm of chromosome 1B originating from the four mentioned cultivars. Altogether, the results of the present study indicate that Qfhs.lfl-1BL is an important component of FHB resistance in European winter wheat and support the view that this QTL would be effective and valuable in backcross breeding programmes. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Aggressiveness spectrum and genetic variability of Fusarium spp. on rice and wheat varieties

Abstract

A total of 106 Fusarium spp. were isolated from infected roots and soil samples of wheat and rice. Of the 106 isolates, 32 from wheat, and 74 from rice, were isolated. Six Fusarium spp. (F. oxysporum, F. moniliforme, F. poae, F. graminearum, F. tricinctum and F. equiseti) were identified at specie level. In aggressiveness tests Fusarium spp. root rot causing fungi were screened out into different aggressiveness classes according to disease severity scales. The aggressiveness of Fusarium spp. was studied on wheat varieties (Inqalab-91 and chakwal-86) and on rice varieties (Basmati-385 and IRRI-6) under controlled conditions. The overall total number of aggressive isolates was higher in rice than in wheat. However, the percentage of severely aggressive isolates was high in wheat, whereas the percentage of moderately and slightly aggressiveness isolates was high in rice. In rice, five isolates were non-aggressive and on wheat 17 were non-aggressive. Random Amplified Polymorphism DNAs (RAPDs) were used to study the polymorphism and genetic variations within the population of Fusarium spp. that established to study correlation between taxonomical and genetical characters of fungi. Five random primers were used P1 (5′-AGGAGGACCC-3′), P2 (5′-ACGAGGGACT-3′), PE7 (5′-AGATGCAGCC-3′), P14 (5′-CCACAGCACG-3′) and PE20 (5′-AACGGTGACC-3′). Each of the 10-mer primers produced results based on the respective banding patterns they generated in present investigations. Primers distinguished the F. oxysporum, F. moniliforme, F. graminearum, F. tricinctum, F. poa and F. equiseti. All the tested primers yielded amplification products, and that were reproducible. Although there was some intraspecific variation with primers, some strains were similar and some were different in banding pattern. In F. oxysporum, F. moniliforme, F. graminearum, F. tricinctum, F. poa and F. equiseti were seen clustered close to one another but each primer separated them unambiguously. All primer (P1, P2, P14, PE7 and PE20) combination produced 62 bands. All primers have shown interspecific and intraspecific variations in banding patterns.     

Variation in noxiousness of different wheat species for celiac patients

Abstract

Peptic-tryptic (PT) digested prolamins from spelt wheat Triticum aestivum ssp. spelta and landraces ERSA 6 and ERSA 8 of farro wheat T. turgidum ssp. dicoccum were found to agglutinate K562(S) cells, and exert strong toxic effects on Caco-2/TC7 cells. Cytotoxicity of spelt prolamins against Caco-2/TC7 cells was greatly reduced by 10-mer peptide QQPQDAVQPF. By contrast, the PT digests from monoccum wheat (Triticum monococcum) and farro landraces Prometeo, L5563, L5540 and L5558 did not exhibit any negative effects on K562(S) and Caco-2/TC7 cells. Toxic genotypes ERSA 6 and ERSA 8 were found to share the same gliadin pattern, which was absent in inactive landraces. Monococcum, farro and spelt wheats differed from each other in their responses to antibodies specific for 13-mer cytotoxic sequence FPGQQQPFPPQQP and 10-mer peptide QQPQDAVQPF. This latter sequence was found to occur in high amounts in common wheat line FG, Phaseoulus vulgaris, Ph. coccineus and Lens culinaria.     

Phylogenetic diversity of Fusarium incarnatum-equiseti species complex isolated from Spanish wheat

Wheat is the most important cereal grown in the European Union and Spain is its fifth largest wheat producer. There is little information about Fusarium species associated with wheat in Spain. Phylogenetic diversity of 51 strains belonging to Fusarium incarnatum-equiseti species complex (FIESC) isolated from Spanish wheat was investigated using partial sequences of the translation elongation factor gene (EF-1α). Maximum-parsimony and Bayesian analysis of aligned DNA sequences resolved 18 haplotypes and 7 phylogenetic species. Strains morphologically identified as F. equiseti belonged to two different phylogenetic species, FIESC-5 and FIESC-14. Some correlation between phylogenetic species and geographical region was found. The present results highlight the potential contribution of FIESC to the mycotoxin contamination of Spanish wheat.