Relationship Between Hardness Genes and Quality in Barley (Hordeum vulgare)

Variation in quality of grains used in malting and brewing

Cereal grains have been domesticated largely from food grains to feed and malting grains. Barley (Hordeum vulgare L.) remains unparalleled in its success as a primary brewing grain. However, there is renewed interest in "alternative" grains for brewing (and distilling) due to attention being placed on flavor, quality, and health (i.e., gluten issues) aspects that they may offer. This review covers basic and general information on "alternative grains" for malting and brewing, as well as an in-depth look at several major biochemical aspects of these grains including starch, protein, polyphenols, and lipids. These traits are described in terms of their effects on processing and flavor, as well as the prospects for improvement through breeding. These aspects have been studied extensively in barley, but little is known about the functional properties in other crops for malting and brewing. In addition, the complex nature of malting and brewing produces a large number of brewing targets but requires extensive processing, laboratory analysis, and accompanying sensory analysis. However, if a better understanding of the potential of alternative crops that can be used in malting and brewing is needed, then significantly more research is required.

Novel Hina alleles created by genome editing increase grain hardness and reduce grain width in barley

The hordoindolina genes (Hina and Hinb) are believed to play critical roles in barley (Hordeum vulgare L.) grain texture. In this study, we created novel alleles of the Hina gene using CRISPR/Cas9 (Clustered regularly inter spaced short palindromic repeat-associated protein, CRISPR-Cas) genome editing. Mutagenesis of single bases in these novel alleles led to loss of Hina protein function in edited lines. The grain hardness index of hina mutants was 95.5 on average, while that of the wild type was only 53.7, indicating successful conversion of soft barley into hard barley. Observation of cross-sectional grain structure using scanning electron microscopy revealed different adhesion levels between starch granules and protein matrix. Starch granules were loose and separated from the protein matrix in the wild type, but deeply trapped and tightly integrated with the protein matrix in hina02 mutants. In addition, the grain width and thousand-grain weight of the hina02 mutant were significantly lower than those of the wild type.

Effect of Genotype and Environment on Food-Related Traits of Organic Winter Naked Barleys

This study aimed to understand how genetics and environment influence organic winter naked barley composition and functionality, and to identify traits that might effectively categorize basic physicochemical functionality of food barley. Across three years, two locations, and 15 genotypes, genotype significantly influenced all 10 food-related traits and was the dominant influence for three. Location significantly influenced eight traits and was dominant for three. Year significantly influenced all traits but was dominant only for one. Of the interactions location * year was the most influential and was the dominant effect for two traits. For all interaction terms where genotype was a component, the effect sizes were either small or non-significant suggesting that even with low leverage traits there is the potential for genetic gain by observing trait rankings across environments. Principal component analysis identified six traits that could serve to categorize basic physicochemical functionality of food barley. These were grain protein content, beta-glucan content, flour-water batter flow, water solvent retention capacity, time to peak viscosity of cooked flour, and hardness of cooked intact grains.

Malting quality of seven genotypes of barley grown in Nepal

There has been very limited work on the malting quality of barley grown in Nepal. This work used completely randomized experiment for seven barley genotypes, namely Xveola-45, Coll#112-114/Muktinath, Xveola-38, Solu uwa, NB-1003/37-1038, NB-1003/37-1034, and Bonus, collected from Hill Crop Research Program (Dolakha, Nepal) to study the effect of genotypes on the chemical composition and functional properties of barley and malt. Barley was steeped for 24 hr followed by 72 hr germination in room temperature (25 ± 3°C). Germinated barley was dried (45°C/6 hr, 50°C/4 hr, 55°C/8 hr, 70°C/1 hr, 80°C/3 hr) in a cabinet drier. Multistage dried barley was then ground to pass through a 250 µm screen. Among the chemical composition, protein and reducing sugar were affected by genotype (p < .05) in barley except for β-glucan. Functional properties, particularly bulk density, water absorption capacity, oil absorption capacity, and viscosity, were affected by genotype (p < .05) in barley, whereas except for density, all the parameters were different (p < .05) for malt. The highest diastatic power among all genotypes was recorded for solu uwa (329.25 ºDP) followed by Muktinath (271.15 ºDP). There was no significant change (p < .05) in a protein of all genotypes after malting, whereas β-glucan and viscosity significantly decreased (p < .05) for all genotypes after malting. The remaining parameters for all genotypes were not affected (p < .05) by malting. Solu uwa had higher enzymatic activity, whereas Xveola-38 and Muktinath were found to be better for complimentary food preparation.

Chromosomal loci associated with endosperm hardness in a malting barley cross

A breeding objective for the malting barley industry is to produce lines with softer, plumper grain containing moderate protein content (9-12%) as they are more likely to imbibe water readily and contain more starch per grain, which in turn produces higher levels of malt extract. In a malting barley mapping population, 'Arapiles' × 'Franklin', the most significant and robust quantitative trait locus (QTL) for endosperm hardness was observed on the short arm of chromosome 1H, across three environments over two growing seasons. This accounted for 22.6% (Horsham 2000), 26.8% (Esperance 2001), and 12.0% (Tarranyurk 2001) of the genetic variance and significantly increased endosperm hardness by 2.06-3.03 SKCS hardness units. Interestingly, Arapiles and Franklin do not vary in Ha locus alleles. Therefore, this region, near the centromere on chromosome 1H, may be of great importance when aiming to manipulate endosperm hardness and malting quality. Interestingly, this region, close to the centromere on chromosome 1H, in our study, aligns with the region of the genome that includes the HvCslF9 and the HvGlb1 genes. Potentially, one or both of these genes could be considered to be candidate genes that influence endosperm hardness in the barley grain. Additional QTLs for endosperm hardness were detected on chromosomes 2H, 3H, 6H and 7H, confirming that the hardness trait in barley is complex and multigenic, similar to many malting quality traits of interest.

Genetic analysis and ecological association of Hina genes based on single nucleotide polymorphisms (SNPs) in wild barley, Hordeum spontaneum

Specific primers were designed to amplify the sequences of Hina genes from 121 wild barley (Hordeum spontaneum) accessions belonging to 18 populations from Iran, Israel and Turkey. Forty-nine single nucleotide polymorphisms (SNPs), nine indels, and 26 haplotypes were determined by sequence analysis. The genetic polymorphism (P), genetic diversity (He), and Shannon's information index (I) in the 18 populations were 0.486, 0.181 and 0.269, respectively. Approximately 2/3 genetic variations of Hina genes were presented within populations, while approximately 1/3 genetic variations were observed between populations. Broad gene flow (Nm= 3.31) and low genetic variation (Gst= 0.0702) were detected. However, the genetic differentiation between populations was independent of geographical distances according to the Mantel test (p = 0.478). The result of Spearman rank correlations (r(s)) showed that the genetic indices (P, He and I) of Hina were not significantly correlated with ecological factors. Only eight SNP positions correlated significantly with ecological factors. Of the eight SNP positions that positively correlated with ecological factors, only one SNP (769, T-C) was located in the coding region; however, it was not responsible for the amino acid change.

Hardness methods for testing maize kernels

Maize is a highly important crop to many countries around the world, through the sale of the maize crop to domestic processors and subsequent production of maize products and also provides a staple food to subsistance farms in undeveloped countries. In many countries, there have been long-term research efforts to develop a suitable hardness method that could assist the maize industry in improving efficiency in processing as well as possibly providing a quality specification for maize growers, which could attract a premium. This paper focuses specifically on hardness and reviews a number of methodologies as well as important biochemical aspects of maize that contribute to maize hardness used internationally. Numerous foods are produced from maize, and hardness has been described as having an impact on food quality. However, the basis of hardness and measurement of hardness are very general and would apply to any use of maize from any country. From the published literature, it would appear that one of the simpler methods used to measure hardness is a grinding step followed by a sieving step, using multiple sieve sizes. This would allow the range in hardness within a sample as well as average particle size and/or coarse/fine ratio to be calculated. Any of these parameters could easily be used as reference values for the development of near-infrared (NIR) spectroscopy calibrations. The development of precise NIR calibrations will provide an excellent tool for breeders, handlers, and processors to deliver specific cultivars in the case of growers and bulk loads in the case of handlers, thereby ensuring the most efficient use of maize by domestic and international processors. This paper also considers previous research describing the biochemical aspects of maize that have been related to maize hardness. Both starch and protein affect hardness, with most research focusing on the storage proteins (zeins). Both the content and composition of the zein fractions affect hardness. Genotypes and growing environment influence the final protein and starch content and, to a lesser extent, composition. However, hardness is a highly heritable trait and, hence, when a desirable level of hardness is finally agreed upon, the breeders will quickly be able to produce material with the hardness levels required by the industry.