Comparative Analysis of Coding and Non-Coding Features within Insect Tolerance Loci in Wheat with Their Homologs in Cereal Genomes.

Food insecurity and malnutrition have reached critical levels with increased human population, climate fluctuations, water shortage; therefore, higher-yielding crops are in the spotlight of numerous studies. Abiotic factors affect the yield of staple food crops; among all, wheat stem sawfly (Cephus cinctus Norton) and orange wheat blossom midge (Sitodiplosis mosellana) are two of the most economically and agronomically harmful insect pests which cause yield loss in cereals, especially in wheat in North America. There is no effective strategy for suppressing this pest damage yet, and only the plants with intrinsic tolerance mechanisms such as solid stem phenotypes for WSS and antixenosis and/or antibiosis mechanisms for OWBM can limit damage. A major QTL and a causal gene for WSS resistance were previously identified in wheat, and 3 major QTLs and a causal gene for OWBM resistance. Here, we present a comparative analysis of coding and non-coding features of these loci of wheat across important cereal crops, barley, rye, oat, and rice. This research paves the way for our cloning and editing of additional WSS and OWBM tolerance gene(s), proteins, and metabolites.

A Novel Sprouted Oat Fermented Beverage: Evaluation of Safety and Health Benefits for Celiac Individuals.

The safety and health effects for celiac people of a novel beverage (SOFB) developed from sprouted oat flour by fermentation with Lactobacillus plantarum was explored. In vitro reactivity against anti-gliadin antibodies (AGA) and antioxidant/anti-inflammatory potential of SOFB in RAW 264.7 macrophages and Caco-2 cells were evaluated. Immunoreactivity against AGA and antioxidant activity were not detected in SOFB, but it exhibited significant anti-inflammatory activity. The tolerability and impact of SOFB consumption for 6 months on nutritional status and intestinal microbiota composition were investigated in 10 celiac adults (five treated and five control). SOFB consumption did not adversely affect duodenal mucosa nor the total IgA or anti-tissue transglutaminase antibody (IgA-tTG) levels in celiac participants, but it significantly decreased total cholesterol levels at all sampling times and folic acid levels at the end of the study compared to the placebo beverage. SOFB administration also shifted gut microbiota, leading to a higher relative abundance of some beneficial bacteria including the genera Subdoligranulum, Ruminococcus and Lactobacillus in the SOFB group. This study provides supporting evidence of the safety of health benefits of a novel functional beverage produced from sprouted oat.

The Role of Oat Nutrients in the Immune System: A Narrative Review.

Optimal nutrition is the foundation for the development and maintenance of a healthy immune system. An optimal supply of nutrients is required for biosynthesis of immune factors and immune cell proliferation. Nutrient deficiency/inadequacy and hidden hunger, which manifests as depleted nutrients reserves, increase the risk of infectious diseases and aggravate disease severity. Therefore, an adequate and balanced diet containing an abundant diversity of foods, nutrients, and non-nutrient chemicals is paramount for an optimal immune defense against infectious diseases, including cold/flu and non-communicable diseases. Some nutrients and foods play a larger role than others in the support of the immune system. Oats are a nutritious whole grain and contain several immunomodulating nutrients. In this narrative review, we discuss the contribution of oat nutrients, including dietary fiber (ß-glucans), copper, iron, selenium, and zinc, polyphenolics (ferulic acid and avenanthramides), and proteins (glutamine) in optimizing the innate and adaptive immune system's response to infections directly by modulating the innate and adaptive immunity and indirectly by eliciting changes in the gut microbiota and related metabolites.

Clinical and in vitro cross-reactivity of cereal grains in children with IgE-mediated wheat allergy

INTRODUCTION AND OBJECTIVES: Wheat and cereal grains have a broad range of cross-reactivity, but the clinical relevance of this cross-reactivity is uncertain. This study aimed to evaluate clinical and in vitro cross-reactivity with barley, oat, and Job's tears among wheat-allergic patients. MATERIALS AND METHODS: Patients aged 5 to 15 years with IgE-mediated wheat allergy were enrolled. Skin prick test (SPT) and specific IgE (sIgE) to wheat, barley, and oat, and SPT to Job's tears were performed. Oral food challenge (OFC) was conducted if the SPT was ≤5 mm in size and there was no history of anaphylaxis to each grain. Profiles of sIgE bound allergens of wheat, barley, and oat, and inhibition ELISA of IgE binding to barley and oat with wheat were performed. RESULTS: Ten patients with a median age of 8 years were enrolled. Nine of those patients had a history of wheat anaphylaxis. The median SPT size and sIgE level to wheat was 7.3 mm and 146.5 kUA/l, respectively. The cross-reactivity rate for barley, oat, and Job's tears was 60.0%, 33.3%, and 20.0%, respectively. Significantly larger SPT size and higher sIgE level were observed in patients with positive cross-reactivity to barley and oat when compared to patients without cross-reactivity. Barley and oat extracts inhibited 59% and 16% of sIgE bound to wheat gliadins and glutenins, respectively. CONCLUSION: The cross-reactivity rate was quite low for oat and Job's tears compared to that of barley; therefore, avoidance of all cereal grains may be unnecessary in patients with severe wheat allergy

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Clinical and in vitro cross-reactivity of cereal grains in children with IgE-mediated wheat allergy.

INTRODUCTION AND OBJECTIVES: Wheat and cereal grains have a broad range of cross-reactivity, but the clinical relevance of this cross-reactivity is uncertain. This study aimed to evaluate clinical and in vitro cross-reactivity with barley, oat, and Job's tears among wheat-allergic patients. MATERIALS AND METHODS: Patients aged 5 to 15 years with IgE-mediated wheat allergy were enrolled. Skin prick test (SPT) and specific IgE (sIgE) to wheat, barley, and oat, and SPT to Job's tears were performed. Oral food challenge (OFC) was conducted if the SPT was ≤5 mm in size and there was no history of anaphylaxis to each grain. Profiles of sIgE bound allergens of wheat, barley, and oat, and inhibition ELISA of IgE binding to barley and oat with wheat were performed. RESULTS: Ten patients with a median age of 8 years were enrolled. Nine of those patients had a history of wheat anaphylaxis. The median SPT size and sIgE level to wheat was 7.3 mm and 146.5 kUA/l, respectively. The cross-reactivity rate for barley, oat, and Job's tears was 60.0%, 33.3%, and 20.0%, respectively. Significantly larger SPT size and higher sIgE level were observed in patients with positive cross-reactivity to barley and oat when compared to patients without cross-reactivity. Barley and oat extracts inhibited 59% and 16% of sIgE bound to wheat gliadins and glutenins, respectively. CONCLUSION: The cross-reactivity rate was quite low for oat and Job's tears compared to that of barley; therefore, avoidance of all cereal grains may be unnecessary in patients with severe wheat allergy.

The Pros and Cons of Using Oat in a Gluten-Free Diet for Celiac Patients.

A therapeutic gluten-free diet often has nutritional limitations. Nutritional qualities such as high protein content, the presence of biologically active and beneficial substances (fiber, beta-glucans, polyunsaturated fatty acids, essential amino acids, antioxidants, vitamins, and minerals), and tolerance by the majority of celiac patients make oat popular for use in gluten-free diet. The health risk of long-time consumption of oat by celiac patients is a matter of debate. The introduction of oat into the diet is only recommended for celiac patients in remission. Furthermore, not every variety of oat is also appropriate for a gluten-free diet. The risk of sensitization and an adverse immunologically mediated reaction is a real threat in some celiac patients. Several unsolved issues still exist which include the following: (1) determination of the susceptibility markers for the subgroup of celiac patients who are at risk because they do not tolerate dietary oat, (2) identification of suitable varieties of oat and estimating the safe dose of oat for the diet, and (3) optimization of methods for detecting the gliadin contamination in raw oat used in a gluten-free diet.

Mapping Oat Crown Rust Resistance Gene Pc45 Confirms Association with PcKM.

Molecular mapping of crown rust resistance genes is important to effectively utilize these genes and improve breeding efficiency through marker-assisted selection. Pc45 is a major race-specific crown rust resistance gene initially identified in the wild hexaploid oat Avena sterilis in the early 1970s. This gene was transferred to cultivated oat (Avena sativa) and has been used as a differential for identification of crown rust races since 1974. Previous research identified an association between virulence to Pc45 and PcKM, a crown rust resistance gene in the varieties 'Kame' and 'Morton'. This study was undertaken to reveal the relationship between Pc45 and PcKMPc45 was studied in the crosses 'AC Morgan'/Pc45 and 'Kasztan'/Pc45, where Pc45 is the differential line carrying Pc45 F2 progenies and F2:3 families of both populations were inoculated with the crown rust isolate CR258 (race NTGG) and single gene segregation ratios were observed. SNP markers for PcKM were tested on these populations and linkage maps were generated. In addition, 17 newly developed SNP markers identified from genotyping-by-sequencing (GBS) data were mapped in these two populations, plus another three populations segregating for Pc45 or PcKMPc45 and PcKM mapped to the same location of Mrg08 (chromosome 12D) of the oat chromosome-anchored consensus map. These results strongly suggest that Pc45 and PcKM are the same resistance gene, but allelism (i.e., functionally different alleles of the same gene) or tight linkage (i.e., two tightly linked genes) cannot be ruled out based on the present data.

PK-profiling method for identifying the expression of resistance-associated genes in partially resistant oats to crown rust.

BACKGROUND: Protein kinases play a key role in plant cell homeostasis and the activation of defense mechanisms. Partial resistance to fungi in plants is interesting because of its durability. However, the variable number of minor loci associated with this type of resistance hampers the reliable identification of the full range of genes involved. The present work reports the technique of protein kinase (PK)-profiling for the identification of the PK genes induced in the partially resistant oats line MN841801-1 following exposure to the fungus Puccinia coronata. This is the first time this technique has been used with cDNA (complementary DNA) from a suppression subtractive hybridization library obtained after the hybridization of cDNAs from inoculated and mock-inoculated plants. RESULTS: Six degenerate primers based on the conserved domains of protein kinases were used in a PK-profiling assay including cDNA from mock-inoculated leaves and subtracted cDNA. Of the 75.7% of sequences cloned and sequenced that showed significant similarity to resistance genes, 76% were found to code for PKs. Translation and ClustalW2 alignment of each sequence cloned with the complete sequences of the most similar B. distachyon PKs allowed those of the partially resistant oat line to be deduced and characterized. Further, a phylogenetic study carried out after alignment of these B. distachyon PK sequences with the most similar protein sequences of related species also allowed to deduce different functions for the PK cloned. RT-qPCR (Reverse Transcription-quantitative PCR) was analyzed on nine representative sequences to validate the reliability of the employed PK-profiling method as a tool for identifying the expression of resistance-associated genes. CONCLUSIONS: PK-profiling would appear to be a useful tool for the identification of the PKs expressed in oats after challenge by P. coronata, and perhaps other pathogens. Most of the PKs studied are related to receptor-like protein kinases expressed shortly after infection. This is in agreement with previous studies indicating a close relationship between partial resistance and the first layer of defense against pathogen used by plants.

Characteristics of Resistance to Puccinia coronata f. sp. avenae in Avena fatua.

Crown rust, caused by Puccinia coronata f. sp. avenae, is the most widespread and harmful fungal disease of oat. The best defense against the pathogen is use of cultivars with genetic resistance, which is effective, economic, and an environmentally friendly alternative to chemical control. However, the continuous evolution of the pathogen can rapidly overcome major gene resistance, creating an urgent need to identify new sources. Wild oat accessions have already proven to be valuable donors of many resistance genes, but the weed species Avena fatua remains underexploited. Its abundance across multiple environments and the frequent occurrence of herbicide-resistant populations demonstrate its ready ability to adapt to biotic and abiotic stresses; yet, surprisingly, there are no extensive studies which describe crown rust resistance occurrence in gene bank stocks of A. fatua. In this study, 204 accessions of A. fatua maintained in the collections of the United States Department of Agriculture (USDA) and Polish National Centre for Plant Genetic Resources were evaluated at the seedling stage for crown rust reaction using host-pathogen tests with five highly diverse and virulent races of P. coronata. Of tested genotypes, 85% showed a heterogeneous infection pattern, while 61% were susceptible or moderately susceptible to all races. Of the 79 resistant A. fatua accessions, seedling resistance to at least two P. coronata isolates was recognized within 19 accessions, with 13 displaying a homogeneously resistant phenotype to one or two races. Accessions showing multiple single seedling resistance to three or four isolates were observed. Based on the seedling reaction to isolates used in the study, 18 infection profiles (IP) were determined. Using UPGMA clustering, resistant accessions were divided into six main clusters encompassing samples with similar IPs. Twelve of 18 patterns allowed us to postulate the likely presence of novel crown rust resistance genes, whose origin was predominantly from Kenya or Egypt. Future work will clarify the genetic basis of the resistances observed here, as well as confirm their potential utility in breeding resistant oat cultivars.

New Sources of Adult Plant and Seedling Resistance to Puccinia coronata f. sp. avenae Identified among Avena sativa Accessions From the National Small Grains Collection.

Accessions of cultivated oat (Avena sativa L.) from the United States Department of Agriculture-Agricultural Research Service Small Grains Collection in Aberdeen, ID were characterized for adult plant resistance (APR) and seedling resistance to crown rust, caused by Puccinia coronata f. sp. avenae. Initially, 607 oat accessions with diverse geographic origins were evaluated in field tests in Baton Rouge, LA. Of those, 97 accessions were not fully susceptible and were tested in the field in St. Paul, MN against a diverse P. coronata f. sp. avenae population. Thirty-six accessions that had some level of resistance in both field tests and mean coefficients of infection of ≤20 were further evaluated for APR and seedling resistance. Among these, four accessions (PI 193040, PI 194201, PI 237090, and PI 247930) were resistant to eight P. coronata f. sp. avenae races as seedlings. Twenty-nine accessions had resistance to at least one of the P. coronata f. sp. avenae races. Three accessions (CIav 2272, CIav 3390, and PI 285583) were fully susceptible to all eight P. coronata f. sp. avenae races as seedlings. Further evaluation of the three seedling-susceptible accessions at the flag leaf stage in a growth chamber resulted in moderately susceptible to moderately resistant responses. The resistance sources presented here may contain genes not deployed in elite oat varieties, and may be useful for future crown rust resistance breeding. The adult and seedling resistance found in accessions of the cultivated oat species is especially valuable because it avoids problems associated with the transfer of genes from wild species to cultivated oat.

Characterization of celiac disease related oat proteins: bases for the development of high quality oat varieties suitable for celiac patients.

Some studies have suggested that the immunogenicity of oats depends on the cultivar. RP-HPLC has been proposed as a useful technique to select varieties of oats with reduced immunogenicity. The aim of this study was to identify both the avenin protein patterns associated with low gluten content and the available variability for the development of new non-toxic oat cultivars. The peaks of alcohol-soluble avenins of a collection of landraces and cultivars of oats have been characterized based on the RP-HPLC elution times. The immunotoxicity of oat varieties for patients with celiac disease (CD) has been tested using a competitive ELISA based on G12 monoclonal antibody. The oat lines show, on average, seven avenin peaks giving profiles with certain similarities. Based on this similarity, most of the accessions have been grouped into avenin patterns. The variability of RP-HPLC profiles of the collection is great, but not sufficient to uniquely identify the different varieties of the set. Overall, the immunogenicity of the collection is less than 20 ppm. However, there is a different distribution of toxicity ranges between the different peak patterns. We conclude that the RP-HPLC technique is useful to establish groups of varieties differing in degree of toxicity for CD patients.

Pure Oats as Part of the Canadian Gluten-Free Diet in Celiac Disease: The Need to Revisit the Issue.

The question about recommending pure, noncontaminated oats as part of the gluten-free diet of patients with celiac disease remains controversial. This might be due to gluten cross contamination and to the possible immunogenicity of some oat cultivars. In view of this controversy, a review of the scientific literature was conducted to highlight the latest findings published between 2008 and 2014 to examine the current knowledge on oats safety and celiac disease in Europe and North America. Results showed that regular oats consumed in Canada are largely contaminated. Overall, the consumption of pure oats has been generally considered to be safe for adults and children. However, it appears that some oat cultivars may trigger an immune response in sensitive individuals. Therefore, further long-term studies on the impact of consumption of oats identifying the cultivar(s) constitute an important step forward for drawing final recommendations. Furthermore, a closer and more accurate monitoring of the dietary intake of noncontaminated oats would be paramount to better determine what its actual contribution in the gluten-free diet of adults and children with celiac disease are in order to draw sound recommendations on the safety of pure oats as part of the gluten-free diet.

Celiac Disease and Gluten-Free Oats: A Canadian Position Based on a Literature Review.

This paper provides an overview of the latest scientific data related to the safety of uncontaminated oats (<20 ppm of gluten) in the diet of individuals with celiac disease (CD). It updates the previous Health Canada position posted on the Health Canada website in 2007 and a related paper published in 2009. It considers a number of recent studies published between January 2008 and January 2015. While recognizing that a few people with celiac disease seem to be clinically intolerant to oats, this review concludes that oats uncontaminated by gluten-containing cereals (wheat, rye, and barley) can be safely ingested by most patients with celiac disease and that there is no conclusive evidence that the consumption of uncontaminated or specially produced oats containing no greater than 20 ppm gluten by patients with celiac disease should be limited to a specific daily amount. However, individuals with CD should observe a stabilization phase before introducing uncontaminated oats to the gluten-free diet (GFD). Oats uncontaminated with gluten should only be introduced after all symptoms of celiac disease have resolved and the individual has been on a GFD for a minimum of 6 months. Long-term regular medical follow-up of these patients is recommended but this is no different recommendation to celiac individuals on a GFD without oats.

Role of oats in celiac disease.

A gluten-free diet is currently the only effective means of treating individuals with celiac disease. Such a diet enables celiac patients to control their symptoms and avoid various complications associated with this condition. However, while the quality of gluten-free foods has significantly improved during recent decades, maintenance of a gluten-free diet does not necessarily ensure adequate nutritional intake. Because oats are an important source of proteins, lipids, vitamins, minerals, and fibre, their inclusion in a gluten-free diet might improve the nutritional status of a celiac patient. Although oats are included in the list of gluten-free ingredients specified in European regulations, their safety when consumed by celiac patients remains debatable. Some studies claim that pure oats are safe for most celiac people, and contamination with other cereal sources is the main problem facing people with this disease. However, it is necessary to consider that oats include many varieties, containing various amino acid sequences and showing different immunoreactivities associated with toxic prolamins. As a result, several studies have shown that the immunogenicity of oats varies depending on the cultivar consumed. Thus, it is essential to thoroughly study the variety of oats used in a food ingredient before including it in a gluten-free diet.

Quantitative Trait Loci from Two Genotypes of Oat (Avena sativa) Conditioning Resistance to Puccinia coronata.

Developing oat cultivars with partial resistance to crown rust would be beneficial and cost-effective for disease management. Two recombinant inbred-line populations were generated by crossing the susceptible cultivar Provena with two partially resistant sources, CDC Boyer and breeding line 94197A1-9-2-2-2-5. A third mapping population was generated by crossing the partially resistant sources to validate the quantitative trait locus (QTL) results. The three populations were evaluated for crown rust severity in the field at Louisiana State University (LSU) in 2009 and 2010 and at the Cereal Disease Laboratory (CDL) in St. Paul, MN, in 2009, 2010, and 2011. An iSelect platform assay containing 5,744 oat single nucleotide polymorphisms was used to genotype the populations. From the 2009 CDL test, linkage analyses revealed two QTLs for partial resistance in the Provena/CDC Boyer population on chromosome 19A. One of the 19A QTLs was also detected in the 2009 LSU test. Another QTL was detected on chromosome 12D in the CDL 2009 test. In the Provena/94197A1-9-2-2-2-5 population, only one QTL was detected, on chromosome 13A, in the CDL 2011 test. The 13A QTL from the Provena/94197A1-9-2-2-2-5 population was validated in the CDC Boyer/94197A1-9-2-2-2-5 population in the CDL 2010 and 2011 tests. Comparative analysis of the significant marker sequences with the rice genome database revealed 15 candidate genes for disease resistance on chromosomes 4 and 6 of rice. These genes could be potential targets for cloning from the two resistant parents.

Cocksfoot mottle virus coat protein is dispensable for the systemic infection.

BACKGROUND: The Sobemovirus genome consists of polycistronic single-stranded positive-sense RNA. The first ORF encodes P1, a suppressor of RNA silencing required for virus movement. The coat protein (CP) is expressed from the 3' proximal ORF3 via subgenomic RNA. In addition to its structural role, the CP of some sobemoviruses has been reported to be required for systemic movement and to interact with P1. The aim of this study was to analyse the role of Cocksfoot mottle virus (CfMV) CP in the suppression of RNA silencing and virus movement. METHODS: Agrobacterium-mediated transient expression method was used for testing CfMV CP capacity to suppress RNA silencing. CP substitution and deletion mutants were generated to examine the role of this protein in CfMV infection, using three host plants (oat, barley and wheat). The viral movement was characterised with CfMV expressing EGFP fused to the C-terminus of CP. RESULTS: In the current study we show that CfMV CP is an additional RNA silencing suppressor. Interestingly, we observed that all CP mutant viruses were able to infect the three tested host plants systemically, although usually with reduced accumulation. CfMV expressing EGFP was detected in epidermal and mesophyll cells of inoculated leaves. Although EGFP fluorescence was not detected in upper leaves, some plants displayed CfMV symptoms. Analysis of the upper leaves revealed that the viruses had lost the EGFP sequence and sometimes also most of the CP gene. CONCLUSIONS: The present study demonstrates that CfMV CP suppresses RNA silencing but, surprisingly, is dispensable for systemic movement. Thus, CfMV does not move as virion in the tested host plants. The composition of the movement RNP complex remains to be elucidated.