Candidate Gene Identification from the Wheat QTL-2DL for Resistance Against Fusarium Head Blight Based on Metabolo-genomics Approach PDF Download
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Author: Udaykumar Kage
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Languages : en
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"Wheat (Triticum aestivum L.) is the most important cereal food crop cultivated around the world. Fusarium head blight (FHB) caused by Fusarium graminearum is one of the most destructive diseases of wheat. Apart from causing huge yield losses, FHB is also known to contaminate grains with mycotoxins that are harmful to human and animal health. Several quantitative trait loci (QTL) have been identified for FHB resistance in wheat, but the mechanisms of resistance and candidate genes underlying them are still unknown. Therefore, in the present study an integrated metabolomics and genomics approach was used to identify the candidate genes and mechanisms of resistance in near-isogenic lines (NILs) of QTL-2DL. The high fold-change in abundance, resistance related (RR) metabolites, identified in rachis samples of NIL-R following pathogen inoculation were, p-coumaroylagmatine, p-coumaroylputrescine, and phosphatidic acids. The candidate gene, p-coumaroylagmatine transferase (TaACT) is associated with the biosynthesis of p-coumaroylagmatine and p-coumaroylputrescine. The diacylglycerol kinase (TaDGK) and glycerol kinase (TaGLI1) are involved in the production of phosphatidic acids. The dissection of QTL based on flanking marker sequencing led to the identification of the transcription factor TaWRKY70 within the QTL-2DL region. In-silico and manual analysis of promoter sequences of TaACT, TaDGK and TaGLI1 showed the presence of WRKY binding sites, and luciferase assay proved their physical interaction in-vivo. Further, functional validation of TaWRKY70 based on virus-induced gene silencing (VIGS) in NIL-R not only confirmed an increase in fungal biomass, but also a decrease in the expression of the downstream resistance genes TaACT, TaDGK and TaGLI1. This was associated with a decrease in abundance of RR metabolites biosynthesized by them, confirming the plausible FHB resistance mechanisms in rachis governed by this QTL. Similarly, in spikelet samples of NIL-R, we found high abundances of phenylpropanoids, glycerophospholipids and fatty acids. These are known to be involved in cutin and suberin biosynthesis. The genes involved in their biosynthetic pathways (TaGPAT3, TaCER5 and TaPAL) were also found in the QTL-2DL region. Transcript abundance of genes in spikelets based on qRT-PCR showed higher expression in the NIL-R compared to NIL-S, confirming the potential role of QTL-2DL in spikelet resistance. However, these genes also have to be functionally validated for further use in breeding. Among the several FHB resistance QTL identified in wheat, this is the first study to identify functional genes from the QTL and their resistance functions." --
Author: Udaykumar Kage
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ISBN:
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Languages : en
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Book Description
"Wheat (Triticum aestivum L.) is the most important cereal food crop cultivated around the world. Fusarium head blight (FHB) caused by Fusarium graminearum is one of the most destructive diseases of wheat. Apart from causing huge yield losses, FHB is also known to contaminate grains with mycotoxins that are harmful to human and animal health. Several quantitative trait loci (QTL) have been identified for FHB resistance in wheat, but the mechanisms of resistance and candidate genes underlying them are still unknown. Therefore, in the present study an integrated metabolomics and genomics approach was used to identify the candidate genes and mechanisms of resistance in near-isogenic lines (NILs) of QTL-2DL. The high fold-change in abundance, resistance related (RR) metabolites, identified in rachis samples of NIL-R following pathogen inoculation were, p-coumaroylagmatine, p-coumaroylputrescine, and phosphatidic acids. The candidate gene, p-coumaroylagmatine transferase (TaACT) is associated with the biosynthesis of p-coumaroylagmatine and p-coumaroylputrescine. The diacylglycerol kinase (TaDGK) and glycerol kinase (TaGLI1) are involved in the production of phosphatidic acids. The dissection of QTL based on flanking marker sequencing led to the identification of the transcription factor TaWRKY70 within the QTL-2DL region. In-silico and manual analysis of promoter sequences of TaACT, TaDGK and TaGLI1 showed the presence of WRKY binding sites, and luciferase assay proved their physical interaction in-vivo. Further, functional validation of TaWRKY70 based on virus-induced gene silencing (VIGS) in NIL-R not only confirmed an increase in fungal biomass, but also a decrease in the expression of the downstream resistance genes TaACT, TaDGK and TaGLI1. This was associated with a decrease in abundance of RR metabolites biosynthesized by them, confirming the plausible FHB resistance mechanisms in rachis governed by this QTL. Similarly, in spikelet samples of NIL-R, we found high abundances of phenylpropanoids, glycerophospholipids and fatty acids. These are known to be involved in cutin and suberin biosynthesis. The genes involved in their biosynthetic pathways (TaGPAT3, TaCER5 and TaPAL) were also found in the QTL-2DL region. Transcript abundance of genes in spikelets based on qRT-PCR showed higher expression in the NIL-R compared to NIL-S, confirming the potential role of QTL-2DL in spikelet resistance. However, these genes also have to be functionally validated for further use in breeding. Among the several FHB resistance QTL identified in wheat, this is the first study to identify functional genes from the QTL and their resistance functions." --
Author: Dhananjay Dhokane
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ISBN:
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Languages : en
Pages :
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"Fusarium head blight (FHB) is one of the most destructive diseases of wheat worldwide. FHB not only cause serious losses in yield but also significantly deteriorates the quality of grains by contaminating them with health hazardous mycotoxins. Plant resistance is considered as the most sustainable and effective strategy to manage FHB and to reduce the accumulation of mycotoxins. However, lack of effective and precise phenotyping methods and limited understanding of the genetics of FHB resistance has hindered the development of resistant cultivars. Resistance to FHB in wheat is quantitative; therefore more than 100 quantitative trait loci (QTL) have been identified and mapped on all chromosomes in wheat. QTL-Fhb2 is the second major QTL that confers high levels of resistance to the spread of Fusarium graminearum (Fg) within a spike through the rachis. However, the genes underlying the QTL and the mechanisms of resistance are still not elucidated.The phenotyping method was improved by developing a qPCR based protocol to precisely quantify the levels of FHB resistance among genotypes, including bleaching symptoms, following single floret inoculation under greenhouse conditions. We used Fg Tri6 gene specific primers to identify the copy number of Tri6 gene in the samples collected after Fg inoculation. The higher copy numbers of Tri6 correlates to higher Fg biomass and more the susceptibility of the genotype to FHB. Based on the protocol developed, we report that the qPCR based method is more sensitive and precise in discriminating genotypes varying in their levels to FHB resistance compared to disease severity analysis. Further, recombinant inbred lines (RILs), carrying resistant (R-RIL) and susceptible (S-RIL) alleles of QTL-Fhb2 were subjected to metabolome and transcriptome profiling following Fg and distilled water (mock) inoculation, to identify candidate genes localized within the QTL-Fhb2. Integrating metabolomic and transcriptomic datasets, we have identified six candidate genes localized within the QTL-Fhb2. The candidate genes localized within the QTL are, 4-coumarate: CoA ligase (4CL), callose synthase (CS), basic Helix Loop Helix (bHLH041) transcription factor, glutathione S-transferase (GST), ABC transporter-4 (ABC4) and cinnamyl alcohol dehydrogenase (CAD). Based on these findings, we report that the QTL-Fhb2 likely confers FHB resistance through combined effect of cell wall reinforcement and Deoxynivalenol (DON) detoxification.Furthermore, a Ta4CL3 gene localized within the QTL-Fhb2 was functionally characterized using virus induced gene silencing and the resistance functions were proven by analyzing disease severity, fungal biomass and metabolic profiles of silenced and non-silenced control plants. Taken together, we report that Ta4CL3 contributes to resistance against the spread of Fg within a spike likely by reinforcing the cell walls, through the deposition of hydroxycinnamic acid amides, lignin and lignans." --
Author: Shivappa Hukkeri Dundappa
Publisher:
ISBN:
Category :
Languages : en
Pages :
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"Fusarium head blight (FHB) is a devastating and dreadful disease of wheat (Triticum aestivum L), which not only reduces the yield but also, affects the grain quality by contaminating with health hazardous mycotoxins. Resistance to FHB in wheat is quantitative in nature, and has led to the identification of several quantitative trait loci (QTL), indicating the additive effects of several genes in governing the resistance. Though, more than hundred QTL conferring FHB resistance have been identified in wheat, genetic controls underlying them are still unknown. The QTL-Fhb5 is one of the major FHB resistant QTL conferring high spikelet resistance and has been consistently mapped using different mapping populations in various environments. However, the gene(s) underlying QTL-Fhb5 conferring resistance and the resistance mechanisms are not elucidated. In our study, we made an attempt to dissect the QTL-Fhb5 and functionally characterize it using integrated a metabolo-genomics approach to identify the putative candidate gene(s) and the plausible mechanisms of resistance. To further explore the candidate genes from QTL-Fhb5 the wheat near-isogenic lines (NILs) carrying resistant (R-NIL) and susceptible (S-NIL) alleles of QTL-Fhb5 derived from Sumai3 genetic background were subjected to semi-comprehensive metabolomic profiling. The metabolomic profiling of NILs identified several resistance related (RR) metabolites belonging to phenylpropanoid pathway in R-NIL as compared to S-NIL. Mapping of RR metabolites in metabolic pathways identified phenylalanine ammonia lyase (PAL), chalcone synthase (CHS) and agmatine p-coumaroyl transferase (ACT) as key metabolic pathway enzymes encoding genes. Further, upon dissection of QTL-Fhb5 using flanking markers, we identified an MYB transcription factor, designated here as TaMYBFhb5, GenBank ID: AHZ33834.1, is localized within the QTL locus. The transcriptional regulation of RR metabolite biosynthetic genes by TaMYBFhb5 TF was confirmed through electrophoretic mobility shift assay (EMSA). The functional characterization of TaMYBFhb5 gene through virus induced gene silencing (VIGS), not only reduced the RR metabolite abundances through downregulation of metabolic pathway genes expressions, but also increased the fungal biomass accumulation and disease severity in silenced R-NIL as compared to non-silenced R-NIL. Further, the resistance functions of TaMYBFhb5 gene was also validated by silencing in Sumai-3 (resistance source of QTL-Fhb5) based on VIGS. To identify the spikelet resistance genes and metabolites induced during F. graminearum (Fg) invasion, we inoculated two wheat genotypes Sumai-3 (resistant) and Roblin (susceptible) with trichothecene producing wild-isolate (FgT) and non-producing mutant-isolate (Fgt) of Fusarium graminearum and subjected them to metabolome profiling and disease severity analysis. Interestingly, both the genotypes showed spikelet infection symptoms within 48 hours post inoculation (hpi) with FgT and Fgt, indicating both the isolates can cause infection. This clearly suggested that the trichothecenes are not essential to infect spikelets. However, the disease severity was higher in the susceptible than in the resistant genotype, especially following FgT infection. In addition, we observed a higher accumulation of phenylpropanoids, lipids, fatty acids and flavonoids in spikelets of the resistant genotype than in susceptible genotype. A semi-quantitative and real-time quantitative PCR revealed the differential accumulation of transcripts for selected biotic stress resistance R genes, in Sumai3 and Roblin spikelets infected with FgT and Fgt. The fungal biomass and deoxynivalenol (DON) trichothecene accumulation in spikelets of Sumai3 were significantly lower than in Roblin. This is the first report on decoding the genetic controls underlying QTL-Fhb5 in wheat for FHB spikelet resistance. " --
Author: Raghavendra Gunnaiah
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Languages : en
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The resistant alleles of two Fhb1 candidate genes, identified in this study, can be suitably stacked into genome of elite cultivars to enhance FHB resistance in wheat." --
Author: Habiballah Hamzehzarghani
Publisher:
ISBN: 9783659675461
Category :
Languages : en
Pages : 212
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Author: Michael Odell Pumphrey
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Category :
Languages : en
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Wheat is the most widely grown and consumed grain crop in the world. In order to meet future agricultural production requirements of a growing population, it is essential that we achieve an increased understanding of the basic components and mechanisms shaping growth and productivity of the polyploid wheat plant. Fusarium head blight (FHB) (syn. "scab") poses a serious threat to the quantity and safety of the world's food supply. The resistance locus Fhb1 has provided partial resistance to FHB of wheat for nearly four decades. Map-based cloning of Fhb1 is justified by its significant and consistent effects on reducing disease levels, the importance of FHB in global wheat production and food safety, and because this gene confers partial resistance to this disease and does not appear to behave in a gene-for-gene manner. A bacterial artificial chromosome (BAC) contig spanning the Fhb1 region was developed from the cultivar 'Chinese Spring', sequenced and seven candidate genes were identified in an ~250 kb region. Cosmid clones for each of the seven candidate genes were isolated from a line containing Fhb1 and used for genetic transformation by biolistic bombardment. Transgenic lines were recovered for five candidate genes and evaluated for FHB resistance. All failed to complement the Fhb1 phenotype. Fhb1 is possibly one of the two remaining candidate genes, an unknown regulatory element in this region, or is not present in Chinese Spring. Traditional views on the effects of polyploidy in allohexaploid wheat have primarily emphasized aspects of coding sequence variation and the enhanced potential to acquire new gene functions through mutation of redundant loci. At the same time, the extent and significance of regulatory variation has been relatively unexplored. Recent investigations have suggested that differential expression of homoeologous transcripts, or subfunctionalization, is common in natural bread wheat. In order to establish a timeline for such regulatory changes and estimate the frequency of non-additive expression of homoeologous transcripts in newly formed T. aestivum, gene expression was characterized in a synthetic T. aestivum line and its T. turgidum and Aegilops tauschii parents by cDNA-SSCP and microarray expression experiments. The cDNA-SSCP analysis of 30 arbitrarily selected homoeologous transcripts revealed that four (~13%) showed differential expression of homoeoalleles in seedling leaf tissue of synthetic T. aestivum. In microarray expression experiments, synthetic T. aestivum gene expression was compared to mid-parent expression level estimates calculated from parental expression levels. Approximately 16% of genes were inferred to display non-additive expression in synthetic T. aestivum. Six homoeologous transcripts classified as non-additively expressed in microarray experiments were characterized by cDNA-SSCP. Expression patterns of these six transcripts suggest that cis-acting regulatory variation is often responsible for non-additive gene expression levels. These results demonstrate that allopolyploidization, per se, results in rapid initiation of differential expression of homoeologous loci and non-additive gene expression in synthetic T. aestivum.
Author: Nosheen Fatima
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Languages : en
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Fusarium head blight (FHB) is one of the most damaging diseases in wheat, which impacts both grain yield and quality drastically. Recently, the disease has become more prevalent in the hard winter wheat (HWW) grown areas of the United States including Oklahoma where FHB has not been reported before. Growing resistant cultivars is the most economical and effective strategy for disease management. To dissect quantitative trait loci (QTL) for FHB resistance in a moderately resistant hard winter wheat (HWW) cultivar, Overland, a population of 186 recombinant inbred lines (RILs) was developed from the cross between Overland and Overley, a susceptible HWW cultivar from Kansas. The RILs were evaluated for FHB type II resistance in one field and three greenhouse experiments and genotyped using genotyping-by-sequencing (GBS) markers. Three FHB resistance QTLs were mapped on Chromosomes 4DL, 4AL, and 5BL. The QTL on 4DL was the most consistent one and explained up to 13% of the phenotypic variation for type II resistance and 14 % for low Fusarium damaged kernels (FDK). Two GBS markers closely linked to the 4DL QTL were successfully converted to Kbioscience competitive allelic specific PCR (KASP) assays and can be used in marker-assisted breeding. In breeding, a single QTL may provide only partial resistance and pyramiding of several resistance QTLs in a cultivar can provide more protection in FHB epidemics. Fhb1 is a major QTL for FHB resistance from a Chinese source and Fhb3 is an alien gene from wild rye grass (Leymus racemosus). To study the effects of these QTLs individually and cumulatively in hard winter wheat backgrounds, they were transferred into two HWW cultivars Overland and Jagger. The results show that Fhb1 significantly increased FHB resistance, but Fhb3 did not. Thus, Fhb3 is not an effective gene for improvement of FHB resistance in HWW.
Author: Yasunari Ogihara
Publisher: Springer
ISBN: 4431556753
Category : Science
Languages : en
Pages : 421
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Book Description
This proceedings is a collection of 46 selected papers that were presented at the 12th International Wheat Genetics Symposium (IWGS). Since the launch of the wheat genome sequencing project in 2005, the arrival of draft genome sequences has marked a new era in wheat genetics and genomics, catalyzing rapid advancement in the field. This book provides a comprehensive review of the forefront of wheat research, across various important topics such as germplasm and genetic diversity, cytogenetics and allopolyploid evolution, genome sequencing, structural and functional genomics, gene function and molecular biology, biotic stress, abiotic stress, grain quality, and classical and molecular breeding. Following an introduction, 9 parts of the book are dedicated to each of these topics. A final, 11th part entitled “Toward Sustainable Wheat Production” contains 7 excellent papers that were presented in the 12th IWGS Special Session supported by the OECD. With rapid population growth and radical climate changes, the world faces a global food crisis and is in need of another Green Revolution to boost yields of wheat and other widely grown staple crops. Although this book focuses on wheat, many of the newly developed techniques and results presented here can be applied to other plant species with large and complex genomes. As such, this volume is highly recommended for all students and researchers in wheat sciences and related plant sciences and for those who are interested in stable food production and food security.
Author: Maria Rosa Simon
Publisher: Frontiers Media SA
ISBN: 2889668223
Category : Science
Languages : en
Pages : 400
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Author: Kazuki Saito
Publisher: Springer Science & Business Media
ISBN: 3540297820
Category : Science
Languages : en
Pages : 351
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Book Description
Metabolomics – which deals with all metabolites of an organism – is a rapidly-emerging sector of post-genome research fields. It plays significant roles in a variety of fields from medicine to agriculture and holds a fundamental position in functional genomics studies and their application in plant biotechnology. This volume comprehensively covers plant metabolomics for the first time. The chapters offer cutting-edge information on analytical technology, bioinformatics and applications. They were all written by leading researchers who have been directly involved in plant metabolomics research throughout the world. Up-to-date information and future developments are described, thereby producing a volume which is a landmark of plant metabolomics research and a beneficial guideline to graduate students and researchers in academia, industry, and technology transfer organizations in all plant science fields.
