The γ-gliadin multigene family in common wheat (Triticum aestivum) and its closely related species

<p>Abstract</p> <p>Background</p> <p>The unique properties of wheat flour primarily depend on gluten, which is the most important source of protein for human being. γ-Gliadins have been considered to be the most ancient of the wheat gluten family. The complex family structure of γ-gliadins complicates the determination of their function. Moreover, γ-gliadins contain several sets of celiac disease epitopes. However, no systematic research has been conducted yet.</p> <p>Results</p> <p>A total of 170 γ-gliadin genes were isolated from common wheat and its closely related species, among which 138 sequences are putatively functional. The ORF lengths of these sequences range from 678 to 1089 bp, and the repetitive region is mainly responsible for the size heterogeneity of γ-gliadins. The repeat motif <b>P</b>(Q/L/S/T/I/V/R/A)<b>F</b>(S/Y/V/Q/I/C/L)<b>P</b>(R/L/S/T/H/C/Y)<b>Q</b>_1–2<b>(P</b>(S/L/T/A/F/H)<b>QQ)</b>_1–2is repeated from 7 to 22 times. Sequence polymorphism and linkage disequilibrium analyses show that γ-gliadins are highly diverse. Phylogenic analyses indicate that there is no obvious discrimination between <it>Sitopsis </it>and <it>Ae. tauschii </it>at the <it>Gli-1 </it>loci, compared with diploid wheat. According to the number and placement of cysteine residues, we defined nine cysteine patterns and 17 subgroups. Alternatively, we classified γ-gliadins into two types based on the length of repetitive domain. Amino acid composition analyses indicate that there is a wide range of essential amino acids in γ-gliadins, and those γ-gliadins from subgroup SG-10 and SG-12 and γ-gliadins with a short repetitive domain are more nutritional. A screening of toxic epitopes shows that γ-gliadins with a pattern of C9 and γ-gliadins with a short repetitive domain almost lack any epitopes.</p> <p>Conclusion</p> <p>γ-Gliadin sequences in wheat and closely related <it>Aegilops </it>species are diverse. Each group/subgroup contributes differently to nutritional quality and epitope content. It is suggested that the genes with a short repetitive domain are more nutritional and valuable. Therefore, it is possible to breed wheat varieties, the γ-gliadins of which are less, even non-toxic and more nutritional.</p

Towards genomic and proteomic studies of protein phosphorylation in plant-pathogen interactions

Phosphorylation is an effective method of post-translational protein modification but understanding its significance is hindered by its biological complexity. Many protein kinases and phosphatases have been identified that connect signal perception mechanisms to plant defence responses. Recent studies of mitogen-activated protein kinases, calcium-dependent protein kinases and other kinases and phosphatases have revealed some important mechanisms, but have also raised new questions. The regulation of any phosphorylation pathway is complex and dynamic. There are many protein kinases and phosphatases in the plant genome, which makes it hard to delineate the phosphorylation machinery fully. Genomics and proteomics have already identified new components and will continue to influence the study of phosphorylation profoundly in plant-pathogen interactions

Exogenous H2O2 and catalase treatments interfere with Tri genes expression in liquid cultures of Fusarium graminearum

International audienceEffect of exogenous H2O2 and catalase was tested in liquid cultures of the deoxynivalenol and 15-acetyldeoxynivalenol-producing fungus Fusarium graminearum. Accordingly to previous results, H2O2 supplementation of the culture medium leads to increased toxin production. This study indicates that this event seems to be linked to a general up regulation of genes involved in the deoxynivalenol and 15-acetyldeoxynivalenol biosynthesis pathway, commonly named Tri genes. In catalase-treated cultures, toxin accumulation is reduced, and Tri genes expression is significantly down regulated. Furthermore, kinetics of expression of several Tri genes is proposed in relation to toxin accumulation. Biological meanings of these findings are discussed

Transcriptome dynamics associated with resistance and susceptibility against fusarium head blight in four wheat genotypes

Abstract Background Fusarium head blight (FHB) of wheat in North America is caused mostly by the fungal pathogen Fusarium graminearum (Fg). Upon exposure to Fg, wheat initiates a series of cellular responses involving massive transcriptional reprogramming. In this study, we analyzed transcriptomics data of four wheat genotypes (Nyubai, Wuhan 1, HC374, and Shaw), at 2 and 4 days post inoculation (dpi) with Fg, using RNA-seq technology. Results A total of 37,772 differentially expressed genes (DEGs) were identified, 28,961 from wheat and 8811 from the pathogen. The susceptible genotype Shaw exhibited the highest number of host and pathogen DEGs, including 2270 DEGs associating with FHB susceptibility. Protein serine/threonine kinases and LRR-RK were associated with susceptibility at 2 dpi, while several ethylene-responsive, WRKY, Myb, bZIP and NAC-domain containing transcription factors were associated with susceptibility at 4 dpi. In the three resistant genotypes, 220 DEGs were associated with resistance. Glutathione S-transferase (GST), membrane proteins and distinct LRR-RKs were associated with FHB resistance across the three genotypes. Genes with unique, high up-regulation by Fg in Wuhan 1 were mostly transiently expressed at 2 dpi, while many defense-associated genes were up-regulated at both 2 and 4 dpi in Nyubai; the majority of unique genes up-regulated in HC374 were detected at 4 dpi only. In the pathogen, most genes showed increased expression between 2 and 4 dpi in all genotypes, with stronger levels in the susceptible host; however two pectate lyases and a hydrolase were expressed higher at 2 dpi, and acetyltransferase activity was highly enriched at 4 dpi. Conclusions There was an early up-regulation of LRR-RKs, different between susceptible and resistant genotypes; subsequently, distinct sets of genes associated with defense response were up-regulated. Differences in expression profiles among the resistant genotypes indicate genotype-specific defense mechanisms. This study also shows a greater resemblance in transcriptomics of HC374 to Nyubai, consistent with their sharing of two FHB resistance QTLs on 3BS and 5AS, compared to Wuhan 1 which carries one QTL on 2DL in common with HC374

Production in vitro de DON et de 15-ADON par Fusarium graminearum : cinétiques d'expression de gènes Tri en conditions de stress oxydatif

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Multiple metabolic pathways for metabolism of L-tryptophan in Fusarium graminearum

Fusarium graminearum is a plant pathogen that can cause the devastating cereal grain disease fusarium head blight (FHB) in temperate regions of the world. Previous studies have shown that F. graminearum can synthetize indole-3-acetic acid (auxin) using L-tryptophan (L-TRP)-dependent pathways. In the present study, we have taken a broader approach to examine the metabolism of L-TRP in F. graminearum liquid culture. Our results showed that F. graminearum was able to transiently produce the indole tryptophol when supplied with L-TRP. Comparative gene expression profiling between L-TRP-treated and control cultures showed that L-TRP treatment induced the up-regulation of a series of genes with predicted function in the metabolism of L-TRP via anthranilic acid and catechol towards the tricarboxylic acid cycle. It is proposed that this metabolic activity provides extra energy for 15-acetyldeoxynivalenol production, as observed in our experiments. This is the first report of the use of L-TRP to increase energy resources in a Fusarium species.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Integrated transcriptome and hormone profiling highlight the role of multiple phytohormone pathways in wheat resistance against fusarium head blight.

Fusarium head blight (FHB or scab) caused by Fusarium spp. is a destructive disease of wheat. Since the most effective sources of FHB resistance are typically associated with unfavorable agronomic traits, breeding commercial cultivars that combine desired agronomic traits and a high level of FHB resistance remains a considerable challenge. A better understanding of the molecular mechanisms governing FHB resistance will help to design more efficient and precise breeding strategies. Here, multiple molecular tools and assays were deployed to compare the resistant variety Sumai3 with three regionally adapted Canadian cultivars. Macroscopic and microscopic disease evaluation established the relative level of Type II FHB resistance of the four varieties and revealed that the F. graminearum infection process displayed substantial temporal differences among organs. The rachis was found to play a critical role in preventing F. graminearum spread within spikes. Large-scale, organ-specific RNA-seq at different times after F. graminearum infection demonstrated that diverse defense mechanisms were expressed faster and more intensely in the spikelet of resistant varieties. The roles of plant hormones during the interaction of wheat with F. graminearum was inferred based on the transcriptomic data obtained and the quantification of the major plant hormones. Salicylic acid and jasmonic acid were found to play predominantly positive roles in FHB resistance, whereas auxin and ABA were associated with susceptibility, and ethylene appeared to play a dual role during the interaction with F graminearum

Development and validation of –expressed molecular markers specific for the long arm of Chromosome 7E

The ditelocentric addition line CS-7EL of the spring wheat (Triticum aestivum L.) cultivar Chinese Spring (CS) contains the long arm of the chromosome 7E from Thinopyrum elongatum (CS-7EL), which confers high resistance to Fusarium head blight. It is of great interest to breeders to integrate the resistance locus (loci) from Th. elongatum into commercial wheat varieties. The objectives of this study were to identify candidate genes expressed from the 7EL chromosome of CS-7EL, to develop 7EL-specific molecular markers, and to validate their usefulness for characterizing recombination between one of the group 7 chromosomes of wheat and Th. elongatum. High-throughput sequencing of Fusarium graminearum–infected and control CS and CS-7EL cDNA libraries was performed using RNA-Seq. A stepwise bioinformatics strategy was applied to assemble the sequences obtained from RNA-Seq and to create a conservative list of candidate genes expressed from the foreign chromosome 7EL. Polymerase chain reaction primer pairs were designed and tested for 135 candidate genes. A total of 48 expressed molecular markers specific for the chromosome 7EL were successfully developed. Screening of progenies from two BC1F2 families from the cross CS-7E(7D) × 2*CSph1b showed that these markers are useful for characterizing recombination events between the chromosomes 7D from wheat and 7E from Th. elongatum