Altered gene expression profiles of wheat genotypes against Fusarium head blight

Dual RNA-sequencing of Fusarium head blight resistance in winter wheat

Fusarium head blight (FHB) is a devastating fungal disease responsible for significant yield losses in wheat and other cereal crops across the globe. FHB infection of wheat spikes results in grain contamination with mycotoxins, reducing both grain quality and yield. Breeding strategies have resulted in the production of FHB-resistant cultivars, however, the underlying molecular mechanisms of resistance in the majority of these cultivars are still poorly understood. To improve our understanding of FHB-resistance, we performed a transcriptomic analysis of FHB-resistant AC Emerson, FHB-moderately resistant AC Morley, and FHB-susceptible CDC Falcon in response to Fusarium graminearum. Wheat spikelets located directly below the point of inoculation were collected at 7-days post inoculation (dpi), where dual RNA-sequencing was performed to explore differential expression patterns between wheat cultivars in addition to the challenging pathogen. Differential expression analysis revealed distinct defense responses within FHB-resistant cultivars including the enrichment of physical defense through the lignin biosynthesis pathway, and DON detoxification through the activity of UDP-glycosyltransferases. Nucleotide sequence variants were also identified broadly between these cultivars with several variants being identified within differentially expressed putative defense genes. Further, F. graminearum demonstrated differential expression of mycotoxin biosynthesis pathways during infection, leading to the identification of putative pathogenicity factors.

Identification of fusarium head blight resistance markers in a genome-wide association study of CIMMYT spring synthetic hexaploid derived wheat lines

Fusarium head blight (FHB), caused by Fusarium graminearum, is one of the most destructive wheat diseases worldwide. FHB infection can dramatically reduce grain yield and quality due to mycotoxins contamination. Wheat resistance to FHB is quantitatively inherited and many low-effect quantitative trait loci (QTL) have been mapped in the wheat genome. Synthetic hexaploid wheat (SHW) represents a novel source of FHB resistance derived from Aegilops tauschii and Triticum turgidum that can be transferred into common wheat (T. aestivum). In this study, a panel of 194 spring Synthetic Hexaploid Derived Wheat (SHDW) lines from the International Maize and Wheat Improvement Center (CIMMYT) was evaluated for FHB response under field conditions over three years (2017-2019). A significant phenotypic variation was found for disease incidence, severity, index, number of Fusarium Damaged Kernels (FDKs), and deoxynivalenol (DON) content. Further, 11 accessions displayed < 10 ppm DON in 2017 and 2019. Genotyping of the SHDW panel using a 90 K Single Nucleotide Polymorphism (SNP) chip array revealed 31 K polymorphic SNPs with a minor allele frequency (MAF) > 5%, which were used for a Genome-Wide Association Study (GWAS) of FHB resistance. A total of 52 significant marker-trait associations for FHB resistance were identified. These included 5 for DON content, 13 for the percentage of FDKs, 11 for the FHB index, 3 for disease incidence, and 20 for disease severity. A survey of genes associated with the markers identified 395 candidate genes that may be involved in FHB resistance. Collectively, our results strongly support the view that utilization of synthetic hexaploid wheat in wheat breeding would enhance diversity and introduce new sources of resistance against FHB into the common wheat gene pool. Further, validated SNP markers associated with FHB resistance may facilitate the screening of wheat populations for FHB resistance.

Transcriptome Dynamic Analysis Reveals New Candidate Genes Associated with Resistance to Fusarium Head Blight in Two Chinese Contrasting Wheat Genotypes

In recent years, Fusarium head blight (FHB) has developed into a global disease that seriously affects the yield and quality of wheat. Effective measures to solve this problem include exploring disease-resistant genes and breeding disease-resistant varieties. In this study, we conducted a comparative transcriptome analysis to identify the important genes that are differentially expressed in FHB medium-resistant (Nankang 1) and FHB medium-susceptible (Shannong 102) wheat varieties for various periods after Fusarium graminearum infection using RNA-seq technology. In total, 96,628 differentially expressed genes (DEGs) were identified, 42,767 from Shannong 102 and 53,861 from Nankang 1 (FDR < 0.05 and |log2FC| > 1). Of these, 5754 and 6841 genes were found to be shared among the three time points in Shannong 102 and Nankang 1, respectively. After inoculation for 48 h, the number of upregulated genes in Nankang 1 was significantly lower than that of Shannong 102, but at 96 h, the number of DEGs in Nankang 1 was higher than that in Shannong 102. This indicated that Shannong 102 and Nankang 1 had different defensive responses to F. graminearum in the early stages of infection. By comparing the DEGs, there were 2282 genes shared at the three time points between the two strains. GO and KEGG analyses of these DEGs showed that the following pathways were associated with disease resistance genes: response to stimulus pathway in GO, glutathione metabolism, phenylpropanoid biosynthesis, plant hormone signal transduction, and plant-pathogen interaction in KEGG. Among them, 16 upregulated genes were identified in the plant-pathogen interaction pathway. There were five upregulated genes, TraesCS5A02G439700, TraesCS5B02G442900, TraesCS5B02G443300, TraesCS5B02G443400, and TraesCS5D02G446900, with significantly higher expression levels in Nankang 1 than in Shannong 102, and these genes may have an important role in regulating the resistance of Nankang 1 to F. graminearum infection. The PR proteins they encode are PR protein 1-9, PR protein 1-6, PR protein 1-7, PR protein 1-7, and PR protein 1-like. In addition, the number of DEGs in Nankang 1 was higher than that in Shannong 102 on almost all chromosomes, except chromosomes 1A and 3D, but especially on chromosomes 6B, 4B, 3B, and 5A. These results indicate that gene expression and the genetic background must be considered for FHB resistance in wheat breeding.

Investigating the Resistance Mechanism of Wheat Varieties to Fusarium Head Blight Using Comparative Metabolomics

Fusarium head blight (FHB) is primarily caused by Fusarium graminearum and severely reduces wheat yield, causing mycotoxin contamination in grains and derived products. F. graminearum-secreted chemical toxins stably accumulate in plant cells, disturbing host metabolic homeostasis. We determined the potential mechanisms underlying FHB resistance and susceptibility in wheat. Three representative wheat varieties (Sumai 3, Yangmai 158, and Annong 8455) were inoculated with F. graminearum and their metabolite changes were assessed and compared. In total, 365 differentiated metabolites were successfully identified. Amino acids and derivatives, carbohydrates, flavonoids, hydroxycinnamate derivatives, lipids, and nucleotides constituted the major changes in response to fungal infection. Changes in defense-associated metabolites, such as flavonoids and hydroxycinnamate derivatives, were dynamic and differed among the varieties. Nucleotide and amino acid metabolism and the tricarboxylic acid cycle were more active in the highly and moderately resistant varieties than in the highly susceptible variety. We demonstrated that two plant-derived metabolites, phenylalanine and malate, significantly suppressed F. graminearum growth. The genes encoding the biosynthetic enzymes for these two metabolites were upregulated in wheat spike during F. graminearum infection. Thus, our findings uncovered the metabolic basis of resistance and susceptibility of wheat to F. graminearum and provided insights into engineering metabolic pathways to enhance FHB resistance in wheat.

Linking Multi-Omics to Wheat Resistance Types to Fusarium Head Blight to Reveal the Underlying Mechanisms

Fusarium head blight (FHB) caused by Fusarium graminearum is a worldwide disease which has destructive effects on wheat production, resulting in severe yield reduction and quality deterioration, while FHB-infected wheat grains are toxic to people and animals due to accumulation of fungal toxins. Although impressive progress towards understanding host resistance has been achieved, our knowledge of the mechanism underlying host resistance is still quite limited due to the complexity of wheat-pathogen interactions. In recent years, disease epidemics, the resistance germplasms and components, the genetic mechanism of FHB, and disease management and control, etc., have been well reviewed. However, the resistance mechanism of FHB is quite complex with Type I, II to V resistances. In this review, we focus on the potential resistance mechanisms by linking different resistance types to multi-omics and emphasize the pathways or genes that may play significant roles in the different types of resistance. Deciphering the complicated mechanism of FHB resistance types in wheat at the integral levels based on multi-omics may help discover the genes or pathways that are critical for different FHB resistance, which could then be utilized and manipulated to improve FHB resistance in wheat breeding programs by using transgenic approaches, gene editing, or marker assisted selection strategies.

Germplasms, genetics and genomics for better control of disastrous wheat Fusarium head blight

Fusarium head blight (FHB), or scab, for its devastating nature to wheat production and food security, has stimulated worldwide attention. Multidisciplinary efforts have been made to fight against FHB for a long time, but the great progress has been achieved only in the genomics era of the past 20 years, particularly in the areas of resistance gene/QTL discovery, resistance mechanism elucidation and molecular breeding for better resistance. This review includes the following nine main sections, (1) FHB incidence, epidemic and impact, (2) causal Fusarium species, distribution and virulence, (3) types of host resistance to FHB, (4) germplasm exploitation for FHB resistance, (5) genetic control of FHB resistance, (6) fine mapping of Fhb1, Fhb2, Fhb4 and Fhb5, (7) cloning of Fhb1, (8) omics-based gene discovery and resistance mechanism study and (9) breeding for better FHB resistance. The advancements that have been made are outstanding and exciting; however, judged by the complicated nature of resistance to hemi-biotrophic pathogens like Fusarium species and lack of immune germplasm, it is still a long way to go to overcome FHB.

Trichothecenes in Cereal Grains - An Update

Trichothecenes are sesquiterpenoid mycotoxins produced by fungi from the order Hypocreales, including members of the Fusarium genus that infect cereal grain crops. Different trichothecene-producing Fusarium species and strains have different trichothecene chemotypes belonging to the Type A and B class. These fungi cause a disease of small grain cereals, called Fusarium head blight, and their toxins contaminate host tissues. As potent inhibitors of eukaryotic protein synthesis, trichothecenes pose a health risk to human and animal consumers of infected cereal grains. In 2009, Foroud and Eudes published a review of trichothecenes in cereal grains for human consumption. As an update to this review, the work herein provides a comprehensive and multi-disciplinary review of the Fusarium trichothecenes covering topics in chemistry and biochemistry, pathogen biology, trichothecene toxicity, molecular mechanisms of resistance or detoxification, genetics of resistance and breeding strategies to reduce their contamination of wheat and barley.

Proteomics of Bulked Rachides Combined with Documented QTL Uncovers Genotype Nonspecific Players of the Fusarium Head Blight Responses in Wheat

Fusarium head blight (FHB) is a destructive disease of wheat that reduces yield and grain quality. High-throughput proteomic techniques have been used to identify a wide range of candidate proteins involved in host resistance. The majority of the published works on the proteomics of the wheat response to Fusarium graminearum infection are case specific. In the current study, a high-throughput quantitative label-free strategy was employed on bulked rachides of F. graminearum-infected wheat collected from multiple genotypes. Differentially accumulated proteins among the following four pools were identified: mock-inoculated FHB-resistant accessions (RM), mock-inoculated FHB-susceptible accessions (SM), F. graminearum-inoculated FHB-resistant accessions (RFg), and F. graminearum-inoculated FHB-susceptible accessions (SFg). Four pairs of comparisons were made: RFg versus RM, SFg versus SM, RM versus SM, and RFg versus SFg. Proteins were projected onto the consensus intervals of previously reported quantitative trait loci in the FHB-resistant pool by blasting against the Chinese Spring reference sequences. In addition to proteins previously reported in the host response to Fusarium spp., new candidates have emerged in association with resistance or susceptibility, including a group 3 late embryogenesis abundant as a resistance-related protein and a purple acid phosphatase as a susceptibility protein. The protein atlas presented here provides new perspectives on the interaction between F. graminearum and wheat.

Integrated mRNA, sRNA, and degradome sequencing reveal oilseed rape complex responses to Sclerotinia sclerotiorum (Lib.) infection

Sclerotinia stem rot (SSR), caused by the fungal pathogen Sclerotinia sclerotiorum, is a devastating disease resulting in yield losses and decreases in seed quality in oilseed rape (Brassica napus) worldwide. However, the molecular mechanisms underlying the response of oilseed rape to S. sclerotiorum infection at the transcriptional and post-transcriptional levels are poorly understood. Here, we used an integrated omics approach (transcriptome, sRNAome, and degradome sequencing) on the Illumina platform to compare the RNA expression and post-transcriptional profiles of oilseed rape plants inoculated or not with S. sclerotiorum. In total, 7,065 differentially expressed genes (DEGs) compared with the mock-inoculated control at 48 hours post inoculation were identified. These DEGs were associated with protein kinases, signal transduction, transcription factors, hormones, pathogenesis-related proteins, secondary metabolism, and transport. In the sRNA-Seq analysis, 77 known and 176 novel miRNAs were identified; however, only 10 known and 41 novel miRNAs were differentially expressed between the samples inoculated or not with S. sclerotiorum. Degradome sequencing predicted 80 cleavage sites with 64 miRNAs. Integrated mRNA, sRNA and degradome sequencing analysis reveal oilseed rape complex responses to S. sclerotiorum infection. This study provides a global view of miRNA and mRNA expression profiles in oilseed rape following S. sclerotiorum infection.

Genome-wide analysis of family-1 UDP glycosyltransferases (UGT) and identification of UGT genes for FHB resistance in wheat (Triticum aestivum L.)

BACKGROUND

Fusarium head blight (FHB), a devastating disease in wheat worldwide, results in yield loses and mycotoxin, such as deoxynivalenol (DON), accumulation in infected grains. DON also facilitates the pathogen colonization and spread of FHB symptoms during disease development. UDP-glycosyltransferase enzymes (UGTs) are known to contribute to detoxification and enhance FHB resistance by glycosylating DON into DON-3-glucoside (D3G) in wheat. However, a comprehensive investigation of wheat (Triticum aestivum) UGT genes is still lacking.

RESULTS

In this study, we carried out a genome-wide analysis of family-1 UDP glycosyltransferases in wheat based on the PSPG conserved box that resulted in the identification of 179 putative UGT genes. The identified genes were clustered into 16 major phylogenetic groups with a lack of phylogenetic group K. The UGT genes were invariably distributed among all the chromosomes of the 3 genomes. At least 10 intron insertion events were found in the UGT sequences, where intron 4 was observed as the most conserved intron. The expression analysis of the wheat UGT genes using both online microarray data and quantitative real-time PCR verification suggested the distinct role of UGT genes in different tissues and developmental stages. The expression of many UGT genes was up-regulated after Fusarium graminearum inoculation, and six of the genes were further verified by RT-qPCR.

CONCLUSION

We identified 179 UGT genes from wheat using the available sequenced wheat genome. This study provides useful insight into the phylogenetic structure, distribution, and expression patterns of family-1 UDP glycosyltransferases in wheat. The results also offer a foundation for future work aimed at elucidating the molecular mechanisms underlying the resistance to FHB and DON accumulation.

Transcriptomics of cereal-Fusarium graminearum interactions: what we have learned so far

The ascomycete fungal pathogen Fusarium graminearum causes the globally important Fusarium head blight (FHB) disease on cereal hosts, such as wheat and barley. In addition to reducing grain yield, infection by this pathogen causes major quality losses. In particular, the contamination of food and feed with the F. graminearum trichothecene toxin deoxynivalenol (DON) can have many adverse short- and long-term effects on human and animal health. During the last decade, the interaction between F. graminearum and both cereal and model hosts has been extensively studied through transcriptomic analyses. In this review, we present an overview of how such analyses have advanced our understanding of this economically important plant-microbe interaction. From a host point of view, the transcriptomes of FHB-resistant and FHB-susceptible cereal genotypes, including near-isogenic lines (NILs) that differ by the presence or absence of quantitative trait loci (QTLs), have been studied to understand the mechanisms of disease resistance afforded by such QTLs. Transcriptomic analyses employed to dissect host responses to DON have facilitated the identification of the genes involved in toxin detoxification and disease resistance. From the pathogen point of view, the transcriptome of F. graminearum during pathogenic vs. saprophytic growth, or when infecting different cereal hosts or different tissues of the same host, have been studied. In addition, comparative transcriptomic analyses of F. graminearum knock-out mutants with altered virulence have provided new insights into pathogenicity-related processes. The F. graminearum transcriptomic data generated over the years are now being exploited to build a systems level understanding of the biology of this pathogen, with an ultimate aim of developing effective and sustainable disease prevention strategies.

Comparative Transcriptome Profiles of Near-Isogenic Hexaploid Wheat Lines Differing for Effective Alleles at the 2DL FHB Resistance QTL

Fusarium head blight (FHB), caused by the fungus Fusarium graminearum, represents one of the major wheat diseases worldwide, determining severe yield losses and reduction of grain quality due to the accumulation of mycotoxins. The molecular response associated with the wheat 2DL FHB resistance QTL was mined through a comprehensive transcriptomic analysis of the early response to F. graminearum infection, at 3 days post-inoculation, in spikelets and rachis. The analyses were conducted on two near isogenic lines (NILs) differing for the presence of the 2DL QTL (2-2618, resistant 2DL+ and 2-2890, susceptible null). The general response to fungal infection in terms of mRNAs accumulation trend was similar in both NILs, even though involving an higher number of DEGs in the susceptible NIL, and included down-regulation of the primary and energy metabolism, up-regulation of enzymes implicated in lignin and phenylpropanoid biosynthesis, activation of hormons biosynthesis and signal transduction pathways and genes involved in redox homeostasis and transcriptional regulation. The search for candidate genes with expression profiles associated with the 2DL QTL for FHB resistance led to the discovery of processes differentially modulated in the R and S NILs related to cell wall metabolism, sugar and JA signaling, signal reception and transduction, regulation of the redox status and transcription factors. Wheat FHB response-related miRNAs differentially regulated were also identified as putatively implicated in the superoxide dismutase activities and affecting genes regulating responses to biotic/abiotic stresses and auxin signaling. Altered gene expression was also observed for fungal non-codingRNAs. The putative targets of two of these were represented by the wheat gene WIR1A, involved in resistance response, and a gene encoding a jacalin-related lectin protein, which participate in biotic and abiotic stress response, supporting the presence of a cross-talk between the plant and the fungus.

Comparative Analysis of Deoxynivalenol Biosynthesis Related Gene Expression among Different Chemotypes of Fusarium graminearum in Spring Wheat

Fusarium mycotoxins, deoxynivalenol (DON) and nivalenol (NIV) act as virulence factors and are essential for symptom development after initial infection in wheat. To date, 16 genes have been identified in the DON biosynthesis pathway. However, a comparative gene expression analysis in different chemotypes of Fusarium graminearum in response to Fusarium head blight infection remains to be explored. Therefore, in this study, nine genes that involved in trichothecene biosynthesis were analyzed among 3-acetyldeoxynivalenol (3-ADON), 15-acetyldeoxynivalenol (15-ADON) and nivalenol producing F. graminearum strains in a time course study. Quantitative reverse transcription polymerase chain reaction revealed that the expression of all examined TRI gene transcripts initiated at 2 days post-inoculation (dpi), peaked at three to four dpi and gradually decreased at seven dpi. The early induction of TRI genes indicates that presence of high levels of TRI gene transcripts at early stages is important to initiate the biosynthetic pathway of DON and NIV. Comparison of gene expression among the three chemotypes showed that relative expression of TRI genes was higher in 3-ADON producing strains compared with 15-ADON and NIV strains. Comparatively higher levels of gene expression may contribute to the higher levels of DON produced by 3-ADON strains in infected grains.

Integrated Metabolo-Transcriptomics Reveals Fusarium Head Blight Candidate Resistance Genes in Wheat QTL-Fhb2

BACKGROUND

Fusarium head blight (FHB) caused by Fusarium graminearum not only causes severe losses in yield, but also reduces quality of wheat grain by accumulating mycotoxins. Breeding for host plant resistance is considered as the best strategy to manage FHB. Resistance in wheat to FHB is quantitative in nature, involving cumulative effects of many genes governing resistance. The poor understanding of genetics and lack of precise phenotyping has hindered the development of FHB resistant cultivars. Though more than 100 QTLs imparting FHB resistance have been reported, none discovered the specific genes localized within the QTL region, nor the underlying mechanisms of resistance.

FINDINGS

In our study recombinant inbred lines (RILs) carrying resistant (R-RIL) and susceptible (S-RIL) alleles of QTL-Fhb2 were subjected to metabolome and transcriptome profiling to discover the candidate genes. Metabolome profiling detected a higher abundance of metabolites belonging to phenylpropanoid, lignin, glycerophospholipid, flavonoid, fatty acid, and terpenoid biosynthetic pathways in R-RIL than in S-RIL. Transcriptome analysis revealed up-regulation of several receptor kinases, transcription factors, signaling, mycotoxin detoxification and resistance related genes. The dissection of QTL-Fhb2 using flanking marker sequences, integrating metabolomic and transcriptomic datasets, identified 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) as putative resistance genes localized within the QTL-Fhb2 region.

CONCLUSION

Some of the identified genes within the QTL region are associated with structural resistance through cell wall reinforcement, reducing the spread of pathogen through rachis within a spike and few other genes that detoxify DON, the virulence factor, thus eventually reducing disease severity. In conclusion, we report that the wheat resistance QTL-Fhb2 is associated with high rachis resistance through additive resistance effects of genes, based on cell wall enforcement and detoxification of DON. Following further functional characterization and validation, these resistance genes can be used to replace the genes in susceptible commercial cultivars, if nonfunctional, based on genome editing to improve FHB resistance.

RNA-seq Transcriptome Response of Flax (Linum usitatissimum L.) to the Pathogenic Fungus Fusarium oxysporum f. sp. lini

Fusarium oxysporum f. sp. lini is a hemibiotrophic fungus that causes wilt in flax. Along with rust, fusarium wilt has become an important factor in flax production worldwide. Resistant flax cultivars have been used to manage the disease, but the resistance varies, depending on the interactions between specific cultivars and isolates of the pathogen. This interaction has a strong molecular basis, but no genomic information is available on how the plant responds to attempted infection, to inform breeding programs on potential candidate genes to evaluate or improve resistance across cultivars. In the current study, disease progression in two flax cultivars [Crop Development Center (CDC) Bethune and Lutea], showed earlier disease symptoms and higher susceptibility in the later cultivar. Chitinase gene expression was also divergent and demonstrated and earlier molecular response in Lutea. The most resistant cultivar (CDC Bethune) was used for a full RNA-seq transcriptome study through a time course at 2, 4, 8, and 18 days post-inoculation (DPI). While over 100 genes were significantly differentially expressed at both 4 and 8 DPI, the broadest deployment of plant defense responses was evident at 18 DPI with transcripts of more than 1,000 genes responding to the treatment. These genes evidenced a reception and transduction of pathogen signals, a large transcriptional reprogramming, induction of hormone signaling, activation of pathogenesis-related genes, and changes in secondary metabolism. Among these, several key genes that consistently appear in studies of plant-pathogen interactions, had increased transcript abundance in our study, and constitute suitable candidates for resistance breeding programs. These included: an induced RPMI-induced protein kinase; transcription factors WRKY3, WRKY70, WRKY75, MYB113, and MYB108; the ethylene response factors ERF1 and ERF14; two genes involved in auxin/glucosinolate precursor synthesis (CYP79B2 and CYP79B3); the flavonoid-related enzymes chalcone synthase, dihydroflavonol reductase and multiple anthocyanidin synthases; and a peroxidase implicated in lignin formation (PRX52). Additionally, regulation of some genes indicated potential pathogen manipulation to facilitate infection; these included four disease resistance proteins that were repressed, indole acetic acid amido/amino hydrolases which were upregulated, activated expansins and glucanases, amino acid transporters and aquaporins, and finally, repression of major latex proteins.

Genome-wide transcriptional profiling of wheat infected with Fusarium graminearum

Fusarium head blight (FHB) is a destructive disease in wheat caused by Fusarium graminearum (F. g). It infects during the flowering stage favored by warm and highly humid climates. In order to understand possible wheat defense mechanism, gene expression analysis in response to F. g was undertaken in three genotypes of wheat, Japanese landrace cultivar Nobeokabouzu (highly resistant), Chinese cv. Sumai 3 (resistant) and Australian cv. Gamenya (susceptible). For microarray analysis, 3 and 7 days after inoculation (dai) samples were used in Agilent wheat custom array 4x38k. At 3 dai, the highest number of genes was up-regulated in Nobeokabouzu followed by Sumai 3 and minimum expression in Gamenya. Whereas at 7 dai, Sumai 3 expressed more genes compared to others. Further narrowing down by excluding commonly expressed genes in three genotypes and grouping according to the gene function has identified differentially high expression of genes involved in detoxification process such as multidrug resistant protein, multidrug resistance-associated protein, UDP-glycosyltransferase and ABC transporters in Nobeokabouzu at 3 dai. However in Sumai 3 many defense-related genes such as peroxidase, proteases and genes involved in plant cell wall defense at 7 dai were identified. These findings showed the difference of molecular defense mechanism among the cultivars in response to the pathogen. The complete data was accessed in NCBI GEO database with accession number GSE59721.

Transcriptome analysis of wheat inoculated with Fusarium graminearum

Plants are frequently exposed to microorganisms like fungi, bacteria, and viruses that cause biotic stresses. Fusarium head blight (FHB) is an economically risky wheat disease, which occurs upon Fusarium graminearum (Fg) infection. Moderately susceptible (cv. "Mizrak 98") and susceptible (cv. "Gun 91") winter type bread wheat cultivars were subjected to transcriptional profiling after exposure to Fg infection. To examine the early response to the pathogen in wheat, we measured gene expression alterations in mock and pathogen inoculated root crown of moderately susceptible (MS) and susceptible cultivars at 12 hours after inoculation (hai) using 12X135K microarray chip. The transcriptome analyses revealed that out of 39,179 transcripts, 3668 genes in microarray were significantly regulated at least in one time comparison. The majority of differentially regulated transcripts were associated with disease response and the gene expression mechanism. When the cultivars were compared, a number of transcripts and expression alterations varied within the cultivars. Especially membrane related transcripts were detected as differentially expressed. Moreover, diverse transcription factors showed significant fold change values among the cultivars. This study presented new insights to understand the early response of selected cultivars to the Fg at 12 hai. Through the KEGG analysis, we observed that the most altered transcripts were associated with starch and sucrose metabolism and gluconeogenesis pathways.