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Cereal Research Communications
Authors: Barbara Steiner, Katharina Schieszl, Ewelina Litwicka, Harald Kurz, Marc Lemmens, Haiyan Jia, Gary Muehlbauer, and Hermann Buerstmayr

Molecular mapping led to the identification of two major Fusarium head blight (FHB) resistance QTL, Fhb1 and Qfhs.ifa-5A . The actual function of the resistance genes is still unknown. The resistant line CM82036, the susceptible line Remus and six closely related lines were analyzed for differential gene expression after Fusarium attack. The related lines show contrasting levels of FHB resistance due to the possession of Fhb1 and Qfhs.ifa-5A . At anthesis plants were challenged by Fusarium graminearum or water and at six time points after inoculation gene expression of specific wheat floral tissue was analyzed by cDNA-AFLPs and the Affymetrix Wheat GeneChip.0.44% of the analyzed gene tags by cDNA-AFLPs displayed differential expressions after Fusarium attack depending on the genotype. Five of the gene tags were associated with the FHB resistance level of the genotypes and the possession of resistance alleles at Fhb1 and Qfhs.ifa-5A . These gene tags show homologies to a UDP-glucosyltransferase, wheat phenylalanine ammonia-lyase, DnaJ-like protein, pathogenesis-related family protein and a rice cDNA clone with unknown function. A thorough comparative analysis with the data gained by the Wheat GeneChip experiments is in progress.

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Fungal diseases pose a great challenge to Canadian barley production, among which are Fusarium head blight (FHB), yellow rust and scald. An integrated management approach is needed to mitigate these diseases, in which breeding for host resistance is the most effective component. Constant evaluation of advanced breeding lines for their resistance to the diseases is important for making steady progression. The main objective of this study was to screen 1,174 barley accessions, from a collaborative project between the Field Crop Development Center (FCDC), Alberta, Canada, and the International Maize and Wheat Improvement Center (CIMMYT), Mexico for their reactions to the three diseases. For FHB a 1-5 scale was employed to discard the very susceptible material in 2012 and 2013. In 2014, 514 most resistant lines having the score 1 in 2013 were re-evaluated in a replicated experiment. The most promising 166 genotypes were selected and advanced for their last evaluation in 2015 where FHB index was measured. Simultaneously, these 166 genotypes were subjected to two more experiments to test their reactions against stripe rust and scald. Eighteen two-rowed barley genotypes exhibiting broad-spectrum resistance to all of the three evaluated diseases were identified in addition to 40 lines combining FHB resistance with resistance to Mexican isolates and natural fungal population of either of the two foliar diseases and could be utilized in breeding programs aimed at improving resistance to multiple barley leaf and head blight diseases.

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Langdon(Dic-3A)-10 line carrying the QTL Qfhs.ndsu-3AS from T. turgidum ssp. dicoccoides that confers Type II resistance to Fusarium head blight (FHB) was crossed with Argentinean durum wheat cultivars. F4 progeny were screened with the microsatellite locus Xgwm2, tightly linked to the Qfhs.ndsu-3A region. Reaction of these plants and parents to FHB was evaluated at 7, 14 and 21 days post-inoculation (dpi) with F. graminearum; severity (% symptomatic spikelets/spike) and AUDPC (area under disease progress curve) were calculated. F4 progeny carrying the resistance allele in heterozygous or in homozygous condition showed significantly lower scab damage at 21 dpi and slower progress of disease than cultivated parents. Our results indicate that the resistance Qfhs.ndsu-3AS has a stable dominance expression in genetic backgrounds of durum cultivars and demonstrate that the linked microsatellite is an effective molecular tool for resistance screening. This work offers valuable information for Qfhs.ndsu-3AS utilization in wheat breeding programs.

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Fusarium head blight (FHB), mainly caused by Fusarium graminearum , is a very serious disease in wheat and barley production area. FHB epidemics cause yield decreases and production of mycotoxin that renders the grain useless for flour and malt products. Understanding the infection mechanism of F. graminearum plays an important role for the disease control. In present study, green fluorescence protein (GFP)-tagged were infected to wheat and barley varieties by single floret injection and screened via GFP signal. Results showed similar infection pattern of F. graminearum on both wheat and barley. Pathogen geminated in the inoculated spikelets, grew on the top of ovary or between lemma and palea, and extended towards and through rachis to the adjacent spikelets to infect the whole spike. When a spike of cultivar with FHB resistance was inoculated by F. graminearum , only the injected spikelet showed symptom at 6 days past inoculation (dpi). GFP signals indicated that F. graminearum colonized only in the inoculated spikelet and stop at the compact tissue of rachilla at 6 dpi. On the contrary, the diseased spikelets were up to 5 at 6 dpi in the spike of cultivars susceptible to FHB. F. graminearum extended through compact tissue to rachis and infected to the adjacent spikelets by spreading upward and downward to adjacent florets inter- and intra-cellularly in vascular bundles and cortical tissue of the rachis.

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Aggressiveness variation among 16 isolates of four Fusarium species (F. culmorum, F. solani, F. verticillioides and F. equiseti) causing Fusarium head blight (FHB) was studied in vitro. Evaluation of three aggressiveness criteria involved in a Petri-dish test: germination rate reduction, standardized area under disease progress curve (AUDPCstandard), and coleoptile length reduction was carried out on the barley cultivar Arabi Aswad. Results showed differences between barley plants inoculated with FHB isolates and control for the three tested aggressiveness criteria. Regarding AUDPCstandard and Petri-dish aggressiveness index which is calculated from the mean value of three aggressiveness criteria, within and among variation was detected. Intra- and inter-species variability was not distinguished for the other two aggressiveness criteria. However, pathogenic level observed among 16 isolates can not be differentiated within the four FHB species. Significant correlation was detected only between AUDPCstandard and Petri-dish aggressiveness index. The results were comparable with those previously obtained using the same fungal isolates on wheat cultivar in vitro. It seems that FHB isolates recovered from wheat spikes and tested on wheat plants showed a similar range of aggressiveness on a barley cultivar, Arabi Aswad.

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Fusarium head blight (FHB) is an important disease of wheat causing significant yield and quality losses globally. Breeding for host plant resistance is an economic approach to FHB control and management. The aim of this study was to identify potential sources of resistance from newly developed recombinant inbred lines (RILs) of wheat. A total of 778 RILs were developed through a bi-parental mating design followed by continuous selfing and selection. The RILs along with their eight parental lines (Baviaans, Buffels, Duzi, #910, #936, #937, #942 and #1036) and FHB resistant check cultivar ‘Sumai 3’ and susceptible check ‘SST 806’ were field evaluated across four environments in South Africa. Fusarium graminearum isolates were artificially inoculated to initiate infection and disease development. The percentage of wheat spikes showing FHB symptoms were scored. The research identified six percent of the RILs with disease resistance. Heritability for FHB resistance was the highest (64%) indicating the possibility of achieving higher selection gains for FHB resistance across the selected environments. The following five RILs were identified as potential sources of resistance: 681 (Buffels/1036-71), 134 (Duzi/910-8), 22 (Baviaans/910-22), 717 (Baviaans/937-8) and 133 (Duzi/910-7) with mean FHB scores of 6.8%, 7.8%, 9.5%, 9.8% and 10%, respectively. The selected lines expressed comparatively similar levels of resistance compared with that of Sumai 3. The identified RILs are useful genetic resources for resistance breeding against FHB disease of wheat. Since the presence of the F. graminearum is associated with deoxynivalenol (DON) accumulation, the DON levels amongst the selected lines should be determined to ensure the release of improved wheat cultivars with reduced levels of DON accumulation.

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Cereal Research Communications
Authors: S.M. Pirseyedi, A. Kumar, F. Ghavami, J.B. Hegstad, M. Mergoum, M. Mazaheri, S.F. Kianian, and E.M. Elias

Fusarium head blight (FHB) damage in durum wheat (Triticum turgidum L. var. durum Desf., turgidum) inflicted massive economic losses worldwide. Meanwhile, FHB resistant durum wheat germplasm is extremely limited. ‘Tunisian108’ is a newly identified tetraploid wheat with FHB resistance. However, genomic regions in ‘Tunisian108’ that significantly associated with FHB resistance are yet unclear. Therefore, a population of 171 backcross inbred lines (BC1F7) derived from a cross between ‘Tunisian108’ and a susceptible durum cultivar ‘Ben’ was characterized. Fusarium graminearum (R010, R1267, and R1322) was point inoculated (greenhouse) or spawn inoculated (field) in 2010 and 2011. Disease severity, Fusarium-damaged kernel (FDK) and mycotoxins were measured. Analysis of variance showed significant genotype and genotype by environment effect on all traits. Approximately 8% of the lines in field and 25% of the lines in greenhouse were more resistance than Tunisian108. A framework linkage map of 267 DArt plus 62 SSR markers was developed representing 239 unique loci and covering a total distance of 1887.6 cM. Composite interval mapping revealed nine QTL for FHB severity, four QTL for DON, and four QTL for FDK on seven chromosomes. Two novel QTL, Qfhb.ndsu-3BL and Qfhb.ndsu-2B, were identified for disease severity, explaining 11 and 6% of the phenotypic variation, respectively. Also, a QTL with large effect on severity and a QTL with negative effect on FDK on chromosome 5A were identified. Importantly, a novel region on chromosome 2B was identified with multiple FHB resistance. Validation on these QTL would facilitate the durum wheat resistance breeding.

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Cereal Research Communications
Authors: Hongxiang M, Jinbao Yao, Miaoping Zhou, Xu Zhang, Lijuan Ren, Giuhong Yu, and Weizhong Lu

Wheat Fusarium head blight (FHB) may cause serious losses in grain yield and quality in China. More than 7 million hectares which approximately accounts for 25% of the total areas in China is infected by the disease. The cultivation of wheat varieties with resistance to Fusarium head blight is recognized as one of the most important components to diminish losses due to this disease. Chinese wheat breeders have commenced the research on FHB since 1950s. Wheat cultivars with improved FHB resistance were developed through conventional breeding. Some famous resistant varieties such as Sumai 3, Yangmai 158 and Ning 7840 were released from Jiangsu Academy of Agricultural Sciences, these varieties were widely applied in wheat production and breeding programs. Significant achievements concerning molecular mapping and marker assisted selection have been made in the past decade. The major QTL on chromosome 3BS was identified and located in the same region on chromosome 3BS in Sumai 3, Ning 894037, Wangshuibai, and Chinese Spring. Using SSR marker in this QTL region for assisted selection, some lines with the same resistance to FHB were obtained. New STS markers and SSCP markers were developed and will be tested for the efficiency of MAS. However, further achievements are still hindered by a number of constraints. More FHB resistance genetic resources from landrace in middle to lower reaches of Yangtze River are necessary to be used for improving FHB resistant. The genetic mechanism of the varieties contributing the resistance to improved cultivars is needed to be understood. Development of functional markers for FHB is discussed.

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Cereal Research Communications
Authors: A. Comeau, F. Langevin, V. Caetano, S. Haber, M. Savard, H. Voldeng, G. Fedak, Y. Dion, S. Rioux, J. Gilbert, D. Somers, and R. Martin

It has proven to be an enduring and difficult challenge to generate useful germplasm that resists fusarium head blight (FHB) as effectively as Sumai 3. While focussed genetic approaches may follow a clear path to a well-defined goal of resistance, they run the risk of worsening traits not selected for. It was commonly believed that selecting for good performance under pressure from multiple diseases plus abiotic stress should be a harder task than focussing on the single goal of FHB resistance; and yet the complex, systemic approaches have now been shown to be capable of rapid progress. Moreover, the risks of worsening non-selected traits are lessened, because the selection matrices favour genes, or groups of genes, that are free of major defects arising from linkage or pleiotropy. However, even at the pre-breeding level, environments are needed that stress the tested germplasm abiotically and with multiple diseases, as a broad array of traits must be examined at the same time. Since as much as 98–99% of any population may need to be discarded, the widest possible genetic range of diversity should be investigated. As seen in several bread wheat examples, the critical factors that allow for rapid selection of germplasm resistant to most stresses are: a) use of an extensive range of available biodiversity; b) well-designed planning of numerous crosses; c) the astute application of combinations of biotic and abiotic stresses; and d) fast recycling of multiple-resistant lines into crossing blocks. Analyses of our first attempts (2003–07) with such systemic approaches show that as early as F1-F3, germplasm with minimal defects and resistant to the multiple biotic and abiotic stresses can be selected. This ability to identify and advance trait packages rather than just individual traits also improves efficiency for breeders. The selected germplasm resisted well all diseases of concern in Eastern Canada: FHB, barley yellow dwarf (BYD), rusts, powdery mildew, leaf spots, and root diseases. The best (e.g. FL62R1) had FHB resistance near equivalent to Sumai 3 while displaying good yield potential and agronomic traits. Milling quality still falls short of desired levels, but was a good improvement over Sumai 3. The systemic approach, so described because it integrates the pursuit of multiple traits in complex environments, has now demonstrated, in a Canadian setting, the success achieved earlier in Brazil. This confirmation and extension of the utility of systemic approaches support the case for their wider application.

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. (1997) Achievements of the Zagreb Bc Institute in winter wheat breeding for resistance to Fusarium head blight (FHB) in Croatia. Cereal Research Communications 25: 823–824. Tomasović S

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