Gene for improved nutritional value in barley seed protein

Differences in Ratio of Carbon Stable Isotopes among Barley Grain Milling Fractions with Various Concentrations of Beta-Glucans

The grains of three barley varieties were milled and sieved to obtain respective milling fractions with a content of beta-glucans (b-G) from 1.4 to 10.7%. The enriched fraction obtained by the extraction and precipitation contained 24.7% of b-G. The differences between the ratio of stable C carbon isotopes were established. Milling fractions with coarse particles had more beta-glucans and a more negative ratio of δ13C isotope in comparison to the respective intact barley grain. However, the enriched fraction had a less negative isotope ratio. So, it is not expected that the deviation from the stable isotope ratio of grain in milling fractions is the result of the content of b-G, but it depends on other barley grain constituents. In different parts of barley grain, there are substances with different stable isotope ratios, and by milling and sieving, they are assorted to the same milling fraction with most of the b-G. The method for determining the ratio of a stable carbon isotope in diverse barley grain fractions, applied in this investigation, is potentially opening the possibility for an additional method of screening the concentration of bioactive constituents in barley grain.

Single nucleotide polymorphism (SNP) markers for genetic diversity and population structure study in Ethiopian barley (Hordeum vulgare L.) germplasm

BACKGROUND

High-density single nucleotide polymorphisms (SNPs) are the most abundant and robust form of genetic variants and hence make highly favorable markers to determine the genetic diversity and relationship, enhancing the selection of breeding materials and the discovery of novel genes associated with economically important traits. In this study, a total of 105 barley genotypes were sampled from various agro-ecologies of Ethiopia and genotyped using 10 K single nucleotide polymorphism (SNP) markers. The refined dataset was used to assess genetic diversity and population structure.

RESULTS

The average gene diversity was 0.253, polymorphism information content (PIC) of 0.216, and minor allelic frequency (MAF) of 0.118 this revealed a high genetic variation in barley genotypes. The genetic differentiation also showed the existence of variations, ranging from 0.019 to 0.117, indicating moderate genetic differentiation between barley populations. Analysis of molecular variance (AMOVA) revealed that 46.43% and 52.85% of the total genetic variation occurred within the accessions and populations, respectively. The heat map, principal components and population structure analysis further confirm the presence of four distinct clusters.

CONCLUSIONS

This study confirmed that there is substantial genetic variation among the different barley genotypes. This information is useful in genomics, genetics and barley breeding.

Morphological variations of qualitative traits of barley (Hordeum vulgare L.) accessions in Ethiopia

Ethiopian barley germplasm is a potential source of useful traits to fight the production challenges of barley farming and to enhance yield productivity in favorable and marginal environments. A study was carried out to assess the distribution and patterns of 17 qualitative trait variations among 85 Ethiopian barley accessions using an alpha lattice design with two replications. The Shannon-Weaver diversity (H') index was used to estimate morphological diversity. Fifteen morphological traits of barley accessions originating from various regions of origins and altitude ranges were polymorphic. However, two traits including stem branching and lemma awn were monomorphic. The highest (0.94) overall mean of H' was obtained for glume colour, kernel row and kernel shape. The estimated H' ranged from 0.41 to 0.99 across regions, and 0.52 to 0.99 across altitude ranges with an overall mean of 0.76. The analysis of variance of H' showed significant variation for most studied traits. Principal components analysis revealed that eight traits were the major loading on the first two principal components that describe 38.3% of the total morphological variance. Heat map analysis based on morphological traits of barley accessions was also grouped into three distinct clusters. Thus, the present finding confirmed that the Ethiopian barley accessions showed vast morphological variations across the region of origins and altitude ranges. Based on the result, further evaluation is ongoing to exploit specific gene variations through phenotyping and genotyping trait association.

Barley: a potential cereal for producing healthy and functional foods

Barley is the fourth largest cereal crop in the world. It is mainly used for feeding, beer production and food. Barley is receiving more attention from both agricultural and food scientists because of its special chemical composition and health benefits. In comparison with other cereal crops, including wheat, rice and maize, barley grains are rich in dietary fiber (such as β-glucan) and tocols, which are beneficial to human health. It is well proved that diets rich in those chemicals can provide protection against hypertension, cardiovascular disease, and diabetes. Barley has been widely recognized to be great potential as a healthy or functional food. In this review, we present the information about the studies on physical structure of barley grain and the distribution of main chemical components, nutrient and functional composition of barley grain and their health benefits, and the approaches of improving and utilizing the nutrient and functional chemicals in barley grain. With the development of processing technologies, functional components in barley grains, especially β-glucan, can be efficiently extracted and concentrated. Moreover, nutrient and functional components in barley grains can be efficiently improved by precise breeding and agronomic approaches. The review highlights the great potential of barley used as healthy and functional foods, and may be instructive for better utilization of barley in food processing.

Proteome and Nutritional Shifts Observed in Hordein Double-Mutant Barley Lines

Lysine is the most limiting essential amino acid in cereals, and efforts have been made over the decades to improve the nutritional quality of these grains by limiting storage protein accumulation and increasing lysine content, while maintaining desired agronomic traits. The single lys3 mutation in barley has been shown to significantly increase lysine content but also reduces grain size. Herein, the regulatory effect of the lys3 mutation that controls storage protein accumulation as well as a plethora of critically important processes in cereal seeds was investigated in double mutant barley lines. This was enabled through the generation of three hordein double-mutants by inter-crossing three single hordein mutants, that had all been backcrossed three times to the malting barley cultivar Sloop. Proteome abundance measurements were integrated with their phenotype measurements; proteins were mapped to chromosomal locations and to their corresponding functional classes. These models enabled the prediction of previously unknown points of crosstalk that connect the impact of lys3 mutations to other signalling pathways. In combination, these results provide an improved understanding of how the mutation at the lys3 locus remodels cellular functions and impact phenotype that can be used in selective breeding to generate favourable agronomic traits.

Physiological Genetics Reformed: Bridging the Genome-to-Phenome Gap by Coherent Chemical Fingerprints - the Global Coordinator

Forward-focused molecular genetics is successfully framing DNA diversity and mapping primary gene functions. However, abandoning the classic Linnaean fingerprint link between the phenome and genome by suppressing gene interaction (pleiotropy), has resulted in a genome-to-phenome gap and poor utilization of molecular data. We demonstrate how to bridge this gap by using an example of a barley mutant seed model, where pleiotropy is observed as covarying global molecular patterns that define each endosperm. Global coherence was discovered as a covariate coordinator within and between local genotype specific fingerprints. This implies that any of these fingerprints can select its recombinant global phenotype variant, including composition. Introducing the law of coherence, and the movement of gene complexes by chemical fingerprint traits as selectors, introduces a revolution in understanding physiological molecular genetics and plant-breeding.

Ecophysiology with barley eceriferum (cer) mutants: the effects of humidity and wax crystal structure on yield and vegetative parameters

BACKGROUND AND AIMS

In addition to preventing water loss, plant cuticles must also regulate nutrient loss via leaching. The eceriferum mutants in Hordeum vulgare (barley) potentially influence these functions by altering epicuticular wax structure and composition.

METHODS

Cultivar 'Bonus' and five of its cer mutants were grown under optimal conditions for vegetative growth and maturation, and nine traits were measured. Nutrient and water amounts going through the soil and the amount of simulated rain as deionized water, affecting phyllosphere humidity, delivered during either the vegetative or maturation phase, were varied. Cer leaf genes and three wilty (wlt) mutations were characterized for reaction to toluidine blue and the rate of non-stomatal water loss.

KEY RESULTS

Vegetative phase rain on 'Bonus' significantly decreased kernel weight and numbers by 15-30 %, while in cer.j59 and .c36 decreases of up to 42 % occurred. Maturation phase findings corroborated those from the vegetative phase. Significant pleiotropic effects were identified: cer.j59 decreased culm and spike length and 1000-kernel weight, .c36 decreased kernel number and weight, .i16 decreased spike length and .e8 increased culm height. Excepting Cer.zv and .ym mutations, none of the other 27 Cer leaf genes or wlt mutations played significant roles, if any, in preventing water loss. Cer.zv and .ym mutants lost non-stomatal water 13.5 times faster than those of Cer.j, .yi, .ys and .zp and 18.3 times faster than those of four cultivars and the mutants tested here.

CONCLUSIONS

Using yield to measure the net effect of phyllosphere humidity and wax crystal structure revealed that the former is far more important than the latter. The amenable experimental setup described here can be used to delve deeper. Significant pleiotropic effects were identified for mutations in four Cer genes, of which one is known to participate in wax biosynthesis. Twenty-seven Cer leaf genes and three wlt mutations have little if any effect on water loss.

The Modular Control of Cereal Endosperm Development

Expansion of the human population demands a significant increase in cereal production. The main component of cereal grains is endosperm, a body of starchy endosperm (SE) cells surrounded by aleurone (AL) cells with transfer cells (TC) at the base and embryo surrounding (ESR) cells adjacent to the embryo. The data reviewed here emphasize the modular nature of endosperm by first suggesting that sucrose promotes development of the fertilized triploid endosperm cell. Next, that the basal syncytial endosperm responds to glucose by turning on TC development. The default endosperm cell fate is SE and ESR differentiation is likely activated by signaling from the embryo. Cells on the exterior surface of the endosperm are specified as AL cells.

Wheat Seed Proteins: Factors Influencing Their Content, Composition, and Technological Properties, and Strategies to Reduce Adverse Reactions

Wheat is the primary source of nutrition for many, especially those living in developing countries, and wheat proteins are among the most widely consumed dietary proteins in the world. However, concerns about disorders related to the consumption of wheat and/or wheat gluten proteins have increased sharply in the last 20 years. This review focuses on wheat gluten proteins and amylase trypsin inhibitors, which are considered to be responsible for eliciting most of the intestinal and extraintestinal symptoms experienced by susceptible individuals. Although several approaches have been proposed to reduce the exposure to gluten or immunogenic peptides resulting from its digestion, none have proven sufficiently effective for general use in coeliac-safe diets. Potential approaches to manipulate the content, composition, and technological properties of wheat proteins are therefore discussed, as well as the effects of using gluten isolates in various food systems. Finally, some aspects of the use of gluten-free commodities are discussed.

From metabolome to phenotype: GC-MS metabolomics of developing mutant barley seeds reveals effects of growth, temperature and genotype

The development of crop varieties tolerant to growth temperature fluctuations and improved nutritional value is crucial due to climate change and global population growth. This study investigated the metabolite patterns of developing barley seed as a function of genotype and growth temperature for ideal vegetable protein production and for augmented β-glucan production. Seeds from three barley lines (Bomi, lys3.a and lys5.f) were sampled eight times during grain filling and analysed for metabolites using gas chromatography-mass spectrometry (GC-MS). The lys3.a mutation disrupts a regulator gene, causing an increase in proteins rich in the essential amino acid lysine, while lys5.f carries a mutation in an ADP-glucose transporter gene leading to a significant increase in production of mixed-linkage β-glucan at the expense of α-glucan. Unique metabolic patterns associated with the tricarboxylic acid cycle, shikimate-phenylpropanoid pathway, mevalonate, lipid and carbohydrate metabolism were observed for the barley mutants, whereas growth temperature primarily affected shikimate-phenylpropanoid and lipid metabolism. The study applied recently developed GC-MS metabolomics methods and demonstrated their successful application to link genetic and environmental factors with the seed phenotype of unique and agro-economically important barley models for optimal vegetable protein and dietary fibre production.

Food and nutritional security requires adequate protein as well as energy, delivered from whole-year crop production

Human food security requires the production of sufficient quantities of both high-quality protein and dietary energy. In a series of case-studies from New Zealand, we show that while production of food ingredients from crops on arable land can meet human dietary energy requirements effectively, requirements for high-quality protein are met more efficiently by animal production from such land. We present a model that can be used to assess dietary energy and quality-corrected protein production from various crop and crop/animal production systems, and demonstrate its utility. We extend our analysis with an accompanying economic analysis of commercially-available, pre-prepared or simply-cooked foods that can be produced from our case-study crop and animal products. We calculate the per-person, per-day cost of both quality-corrected protein and dietary energy as provided in the processed foods. We conclude that mixed dairy/cropping systems provide the greatest quantity of high-quality protein per unit price to the consumer, have the highest food energy production and can support the dietary requirements of the highest number of people, when assessed as all-year-round production systems. Global food and nutritional security will largely be an outcome of national or regional agroeconomies addressing their own food needs. We hope that our model will be used for similar analyses of food production systems in other countries, agroecological zones and economies.

Proteomic analysis of mature barley grains from C-hordein antisense lines

Hordeins are the major storage proteins in barley grains and are responsible for their low nutritional quality. Previously, antisense C-hordein barley lines were generated and were shown to contain a more balanced amino acid composition and an altered storage protein profile. In the present study, a proteomic approach that combined two-dimensional gel electrophoresis (2-DE) and mass spectrometry was used to (1) identify the changes in the protein profile of non-storage proteins (salt soluble fraction) in antisense C-hordein barley lines (L1, L2 and L3) and (2) map the differentially expressed proteins compared to the non-transgenic control line (Hordeum vulgare cv. Golden Promise). Moreover, the changes in the proteins were correlated with the more balanced amino acid composition of these lines, with special attention to the lysine content. The results showed that suppression of C-hordein expression does not exclusively affect hordein synthesis and accumulation. The more balanced amino acid composition observed in the transgenic lines L1, L2 and L3 was an indirect result of the profound alterations in the patterns of the non-storage proteins. The observed changes included up-regulated expression of the proteins involved in stress and detoxification (L1), defence (L2 and L3), and storage globulins (L1, L2 and L3). To a lesser extent, the proteins involved in grain metabolism were also changed. Thus, the increased essential amino acids content results from changes in distinct protein sources among the three antisense C-hordein lines analyzed, although the up-regulated expression of lysine-rich proteins was consistently observed in all lines.

Mutational breeding and genetic engineering in the development of high grain protein content

Cereals are the most important crops in the world for both human consumption and animal feed. Improving their nutritional values, such as high protein content, will have significant implications, from establishing healthy lifestyles to helping remediate malnutrition problems worldwide. Besides providing a source of carbohydrate, grain is also a natural source of dietary fiber, vitamins, minerals, specific oils, and other disease-fighting phytocompounds. Even though cereal grains contain relatively little protein compared to legume seeds, they provide protein for the nutrition of humans and livestock that is about 3 times that of legumes. Most cereal seeds lack a few essential amino acids; therefore, they have imbalanced amino acid profiles. Lysine (Lys), threonine (Thr), methionine (Met), and tryptophan (Trp) are among the most critical and are a limiting factor in many grain crops for human nutrition. Tremendous research has been put into the efforts to improve these essential amino acids. Development of high protein content can be outlined in four different approaches through manipulating seed protein bodies, modulating certain biosynthetic pathways to overproduce essential and limiting amino acids, increasing nitrogen relocation to the grain through the introduction of transgenes, and exploiting new genetic variance. Various technologies have been employed to improve protein content including conventional and mutational breeding, genetic engineering, marker-assisted selection, and genomic analysis. Each approach involves a combination of these technologies. Advancements in nutrigenomics and nutrigenetics continue to improve public knowledge at a rapid pace on the importance of specific aspects of food nutrition for optimum fitness and health. An understanding of the molecular basis for human health and genetic predisposition to certain diseases through human genomes enables individuals to personalize their nutritional requirements. It is critically important, therefore, to improve grain protein quality. Highly nutritious grain can be tailored to functional foods to meet the needs for both specific individuals and human populations as a whole.

Morphological diversity of Ethiopian barley (Hordeum vulgare L.) in relation to geographic regions and altitudes

A total of 199 germplasm accessions collected from 10 administrative regions of Ethiopia and four released cultivars, which were used for estimating of error variance, of barley in Ethiopia were field evaluated for nine agronomic traits at Holetta and Bekoji Agricultural Research Centers of Ethiopia during the 2006 main cropping season using non-replicated augmented design plots consisting of four incomplete blocks. The objectives were to assess the extent and pattern of morphological variation in the barley accessions with respect to regions and altitude of collection, to classify the genotypes tested into relatively homogenous groups and to identify the major traits contributing to the overall observed diversity in the germplasm. Genotype variance estimate of regions and altitudes indicated wide variation among accessions depending on the traits involved. The presence of high morphological variation within regions and altitudes particularly above 2000 m a.s.l. indicated the potential of each region and high altitude zones for barley improvement and conservation in the country. The clustering of accessions did not show grouping on the basis of regions of origin. Traits like thousand kernel weight, plant height, days to head and days to maturity accounted for most of the gross variance among the barley accessions and played role in differentiating accessions collected from different regions and altitude classes into principal components. In general because of environmental factors on the observed morphological variation future germplasm collection should consider to explore wide geographical and climatic differences within the country.

Adaptation and diversity along an altitudinal gradient in Ethiopian barley (Hordeum vulgare L.) landraces revealed by molecular analysis

BACKGROUND

Among the cereal crops, barley is the species with the greatest adaptability to a wide range of environments. To determine the level and structure of genetic diversity in barley (Hordeum vulgare L.) landraces from the central highlands of Ethiopia, we have examined the molecular variation at seven nuclear microsatellite loci.

RESULTS

A total of 106 landrace populations were sampled in the two growing seasons (Meher and Belg; the long and short rainy seasons, respectively), across three districts (Ankober, Mojanawadera and Tarmaber), and within each district along an altitudinal gradient (from 1,798 to 3,324 m a.s.l). Overall, although significant, the divergence (e.g. FST) is very low between seasons and geographical districts, while it is high between different classes of altitude. Selection for adaptation to different altitudes appears to be the main factor that has determined the observed clinal variation, along with population-size effects.

CONCLUSIONS

Our data show that barley landraces from Ethiopia are constituted by highly variable local populations (farmer's fields) that have large within-population diversity. These landraces are also shown to be locally adapted, with the major driving force that has shaped their population structure being consistent with selection for adaptation along an altitudinal gradient. Overall, our study highlights the potential of such landraces as a source of useful alleles. Furthermore, these landraces also represent an ideal system to study the processes of adaptation and for the identification of genes and genomic regions that have adaptive roles in crop species.

High-lysine maize: the key discoveries that have made it possible

Forty-five years ago, a paper published by Mertz et al. (Science 145:279-280, 1964) initiated a revolution in the history of plant protein quality and affected dramatically the study of cereal crop storage proteins. The observation of the high lysine content of the endosperm of the opaque-2 (o2) maize mutant was a key factor in bringing about a new concept in the production of cereal seeds with a high nutritional value. It has been a long and very interesting road with astonishing results over these 45 years. We are now probably about to see the release of commercially engineered high-lysine maize lines. We have decided to pinpoint some key contributions to the science behind high-lysine plants and concentrated on the research done on maize, which is possibly the most complete and simple example to illustrate the advances achieved. However, studies on other plant species such as barley and model species such as tobacco are totally relevant and will be briefly addressed.

Primary structure and reactive site of a novel wheat proteinase inhibitor of subtilisin and chymotrypsin

The proteinase inhibitor WSCI, active in inhibiting bacterial subtilisin and a number of animal chymotrypsins, was purified from endosperm of exaploid wheat (Triticum aestivum, c.v. San Pastore) by ion exchange chromatography and its complete amino acid sequence was established by automated Edman degradation. WSCI consists of a single polypeptide chain of 72 amino acid residues, has a molecular mass of 8126.3 Da and a pl of 5.8. The inhibition constants (Ki) for Bacillus licheniformis subtilisin and bovine pancreatic alpha-chymotrypsin are 3.92 x 10(-9) M and 7.24 x 10(-9) M, respectively. The inhibitor contains one methionine and of tryptophan residue and has a high content of essential amino acids (41 over a total of 72 residues), but no cysteines. The primary structure of WSCI shows high similarity with barley subtilisin-chymotrypsin isoinhibitors of the Cl-2 type and with maize subtilisinchymotrypsin inhibitor MPI. Significant degrees of similarity were also found between sequences of WSCI and of other members of the potato inhibitor I family of the serine proteinase inhibitors. The wheat inhibitor WSCI has a single reactive site (the peptide bond between methionyl-48 and glutamyl-49 residues) as identified by affinity chromatography and sequence analysis.

Rapid gastric fluid digestion and biochemical characterization of engineered proteins enriched in essential amino acids

The barley high lysine (BHL) proteins are nutritionally enhanced derivatives of barley chymotrypsin inhibitor-2 (CI-2). A compactly folded new CI-2 derivative, BHL9, was engineered with the highest content of threonine, tryptophan, and isoleucine yet achieved in this protein family (15.1, 9.4, and 12.1 wt %, respectively). BHL9 had an unfolding midpoint of 5.5 M guanidinium chloride, significantly greater than values for wild type (3.9 M) or for the previously most stable BHL protein, BHL8 (3.6 M). BHL9 and all other derivatives were digested within 15 s in simulated gastric fluid (SGF), suggesting nutritional availability upon ingestion. Denaturation of the proteins in SGF minus pepsin was revealed by changes in their fluorescence emission spectra and/or far UV circular dichroism spectra. The proteins lack homology to known allergens. Significantly, the BHL8 and BHL9 proteins were stable to proteases at pH 7.5 or 8.0, attesting to their potential for high expression in plants.

A nucleotide sequence linked to the vrs1 locus for studies of differentiation in cultivated barley (Hordeum vulgare L.)

A PCR-amplified DNA, cMWG699, is linked to the vrs1 (formerly v) locus controlling 2- and 6-rowed spikelets. Restriction analysis of the amplified DNA of 65 varieties from Europe, America, and East Asia revealed 3 alleles, named types K, A and D. Two-rowed varieties were mostly of type K allele, and 6-rowed varieties were mostly of type A allele. The type D allele was found only in three 6-rowed varieties. Sequence comparison of these alleles revealed that the type A allele is more closely related to the type K allele than to the type D allele. The sequence analysis also suggested that the types A and D alleles diverged earlier than when 6-rowed barley arose. On the assumption that 2-rowed barleys were the ancestors of 6-rowed barley, 6-rowed barleys with types A and D alleles probably differentiated from 2-rowed barleys with type A and D alleles, respectively, by independent mutations on the vrs1 locus.