The grain quality of wheat wild relatives in the evolutionary context

Simulation of Daily Iron Intake by Actual Diet Considering Future Trends in Wheat and Rice Biofortification, Environmental, and Dietary Factors: An Italian Case Study

BACKGROUND AND AIM

Cereals' iron content is a major contributor to dietary iron intake in Europe and a potential for biofortification. A simulation of daily iron intake from wheat and rice over the next 20 years will be quantified.

METHODS

Food items, and energy and iron intake by age classes are estimated using the Italian dietary survey (IV SCAI). Iron intake and adequacy estimation trends were categorized in four scenarios compared to a baseline (basic scenario; only climate change effects): over wheat and rice biofortification effects (scenario 1); over the shift in whole wheat consumption of up to 50% of the total amount of wheat-based foods (scenario 2); over the shift in brown rice consumption up to 100% of the total amount of rice (scenario 3); over the cumulative effects of biofortifications and whole wheat and brown rice consumption (scenario 4).

RESULTS

Increasing the iron intake from wheat and rice biofortification and the shift in whole wheat consumption is similar and sufficient to recover the baseline iron depletion effect due to climate change. The shift in brown rice consumption produces a negligible increment in iron intake. The cumulative effects of the corrective actions considered in the scenarios can significantly reduce the iron intake inadequacy, despite not reaching the recommended levels.

CONCLUSIONS

Corrective actions including biofortification and whole grain consumption are still far from ensuring the full recovery in children and females of fertile age as at-risk groups of iron deficiency. Further actions are needed considering other biofortified food sources, fortified foods, and/or dietary food diversification.

Identification of Genomic Regions Conferring Enhanced Zn and Fe Concentration in Wheat Varieties and Introgression Lines Derived from Wild Relatives

Wild and cultivated relatives of wheat are an important source of genetic factors for improving the mineral composition of wheat. In this work, a wheat panel consisting of modern bread wheat varieties, landraces, and introgression lines with genetic material of the wheat species Triticum timopheevii, T. durum, T. dicoccum, and T. dicoccoides and the synthetic line T. kiharae was used to identify loci associated with the grain zinc (GZnC) and iron (GFeC) content. Using a BLINK model, we identified 31 and 73 marker-trait associations (MTAs) for GZnC and GFeC, respectively, of which 19 were novel. Twelve MTAs distributed on chromosomes 1B, 2A, 2B, 5A, and 5B were significantly associated with GZnC, five MTAs on 2A, 2B, and 5D chromosomes were significantly associated with GFeC, and two SNPs located on 2A and 2B were related to the grain concentration of both trace elements. Meanwhile, most of these MTAs were inherited from At and G genomes of T. timopheevii and T. kiharae and positively affected GZnC and GFeC. Eight genes related to iron or zinc transporters, representing diverse gene families, were proposed as the best candidates. Our findings provide an understanding of the genetic basis of grain Zn and Fe accumulation in species of the Timopheevi group and could help in selecting new genotypes containing valuable loci.

Agro-Physiological and DNA Methylation Responses to Salinity Stress in Wheat (Triticum aestivum L.), Aegilops cylindrica Host, and Their Introgressed Lines

Bottlenecks, including limited genetic variation and the ongoing loss of genetic diversity, have hindered the development of modern wheat cultivars., making it crucial to use genetic diversity from wild relatives to improve wheat's adaptation to abiotic stress, such as salinity. This study assessed the phenotypic and epigenetic variation of introgressed wheat lines (BC4F2) derived from hybridizing two wheat cultivars with Aegilops cylindrica (AC). This study assessed the phenotypic and epigenetic variation of 156 introgressed wheat lines (BC4F2) derived from hybridization between wheat cultivars "Chinese Spring" (CS) and "Roshan" (R) and Aegilops cylindrica (AC). These lines and their recurrent parents (total of 158) were evaluated under normal and saline field conditions for the agronomic traits and stress tolerance indices. The data were used to select the most tolerant and most sensitive lines. Then, the selected BC4F2 lines and their parents (AC, CS, and R) were subjected to physiological, DNA cytosine methylation, and expression analysis of HKT1;5, NHX1, and SOS1 genes under control and salt stress conditions. Agro-physiological, epigenetic, and gene expression analyses showed the significant effects of salt stress and genetic background, as well as the differential response of the BC4F2 lines to salt stress. The variations in leaf and root K, Na, and K/Na ratios, and leaf Chla, Chlb, Car, and MDA levels, unlike DPPH radical scavenging levels, between salt-tolerant and salt-sensitive BC4F2 lines under saline conditions indicated a substantial distinction in salinity tolerance responses. RT-qPCR indicated higher expression levels of NHX1 and SOS1 genes in the leaf and root tissues of tolerant lines than those of sensitive lines. Global leaf and root DNA methylation analysis revealed the significant effects of salinity on the methylation modifications and confirmed the successful introgression of the salt-tolerance epigenome from Ae. cylindrica into wheat. Exploiting the genetic diversity of wild wheat relatives is a crucial goal for increasing genetic and epigenetic variation to enhance plant adaptation to salt stress.

Prospects for mineral biofortification of wheat: classical breeding and agronomy

Low intake of micro- and macroelements and vitamins in food negatively affects the health of more than two billion people around the world provoking chronic diseases. For the majority of the world's population, these are soft and durum wheats that provide beneficial nutrients, however their modern high-yielding varieties have a significantly depleted grain mineral composition that have reduced mineral intake through food. Biofortification is a new research trend, whose main goal is to improve the nutritional qualities of agricultural crops using a set of classical (hybridization and selection) methods as well and the modern ones employing gene/QTL mapping, bioinformatic analysis, transgenesis, mutagenesis and genome editing. Using the classical breeding methods, biofortified varieties have been bred as a part of various international programs funded by HarvestPlus, CIMMYT, ICARDA. Despite the promise of transgenesis and genome editing, these labor-intensive methods require significant investments, so these technologies, when applied to wheat, are still at the development stage and cannot be applied routinely. In recent years, the interest in wheat biofortification has increased due to the advances in mapping genes and QTLs for agronomically important traits. The new markers obtained from wheat genome sequencing and application of bioinformatic methods (GWAS, meta-QTL analysis) has expanded our knowledge on the traits that determine the grain mineral concentration and has identified the key gene candidates. This review describes the current research on genetic biofortification of wheat in the world and in Russia and provides information on the use of cultivated and wild-relative germplasms to expand the genetic diversity of modern wheat varieties.

The High-Molecular-Weight Glutenin Subunits of the T. timopheevii (AuAuGG) Group

Polyploid wheats include a group of tetraploids known as Timopheevii (AuAuGG), which are represented by two subspecies: Triticum timopheevii ssp. timopheevii (cultivated) and Triticum timopheevii ssp. araraticum (wild). The combined use of electrophoretic (SDS-PAGE) and chromatographic (RP-HPLC) techniques carried out on high-molecular-weight glutenin subunits (HMW-GSs) permitted the association of different x- and y-type subunits to the A and G genomes and the assessment of allelic variation present at corresponding loci. The results also revealed that in both subspecies, accessions are present that possess expressed y-type subunits at the Glu-A1 locus. Genes corresponding to these subunits were amplified and amplicons corresponding to x- and y-type genes associated with the A genome were detected in all accessions, including those without expressed x- and y-type subunits. The comparison with genes of polyploid wheats confirmed the structural characteristics of typical y-type genes, with the presence of seven cysteine residues and with hexapeptide and nonapeptide repeat motifs. The identification of wild and cultivated T. timopheevii with both x- and y-type glutenin subunits at the Glu-A1 and Glu-G1 loci represents a useful source for the modification of the allelic composition of HMW-GSs in cultivated wheats with the ultimate objective of improving technological properties.

Grain quality traits within the wheat (Triticum spp.) genepool: prospects for improved nutrition through de novo domestication

BACKGROUND

Wild relatives of wheat (Triticum spp.) harbor beneficial alleles for potential improvement and de novo domestication of selected genotypes with advantageous traits. We analyzed the nutrient composition in wild diploid and tetraploid wheats and their domesticated diploid, tetraploid and hexaploid relatives under field conditions in Germany and compared them with modern Triticum aestivum and Triticum durum cultivars. Grain iron (Fe) and zinc (Zn) concentrations, phytate:mineral molar ratios, grain protein content (GPC) and antioxidant activity were analyzed across 125 genotypes.

RESULTS

Grain Fe and Zn concentrations in wild wheats were 72 mg kg-1 and 59 mg kg-1, respectively, with improved bioavailability indicated by Phytate:Fe and Phytate:Zn molar ratios (11.7 and 16.9, respectively) and GPC (231 g kg-1). By comparison, grain Fe and Zn concentrations in landrace taxa were 54 mg kg-1 and 55 mg kg-1, respectively, with lower Phytate:Fe and Phytate:Zn molar ratios (15.1 and 17.5, respectively) and GPC (178 g kg-1). Average grain Fe accumulation in Triticum araraticum was 73 mg kg-1, reaching 116 mg kg-1, with high Fe bioavailability (Phyt:Fe: 11.7; minimum: 7.2). Wild wheats, landraces and modern cultivars showed no differences in antioxidant activity. Triticum zhukovskyi stood out with high grain micronutrient concentrations and favorable molar ratios. It was also the only taxon with elevated antioxidant activity.

CONCLUSION

Our results indicate alteration of grain quality during domestication. T. araraticum has promising genotypes with advantageous grain quality characteristics that could be selected for de novo domestication. Favorable nutritional traits in the GGAA wheat lineage (T. araraticum and T. zhukovskyi) hold promise for improving grain quality traits. © 2024 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Novel Genetic Loci from Triticum timopheevii Associated with Gluten Content Revealed by GWAS in Wheat Breeding Lines

The content and quality of gluten in wheat grain is a distinctive characteristic that determines the final properties of wheat flour. In this study, a genome-wide association study (GWAS) was performed on a wheat panel consisting of bread wheat varieties and the introgression lines (ILs) obtained via hybridization with tetraploid wheat relatives. A total of 17 stable quantitative trait nucleotides (QTNs) located on chromosomes 1D, 2A, 2B, 3D, 5A, 6A, 7B, and 7D that explained up to 21% of the phenotypic variation were identified. Among them, the QTLs on chromosomes 2A and 7B were found to contain three and six linked SNP markers, respectively. Comparative analysis of wheat genotypes according to the composition of haplotypes for the three closely linked SNPs of chromosome 2A indicated that haplotype TT/AA/GG was characteristic of ten ILs containing introgressions from T. timopheevii. The gluten content in the plants with TT/AA/GG haplotype was significantly higher than in the varieties with haplotype GG/GG/AA. Having compared the newly obtained data with the previously reported quantitative trait loci (QTLs) we inferred that the locus on chromosome 2A inherited from T. timopheevii is potentially novel. The introgression lines containing the new locus can be used as sources of genetic factors to improve the quality traits of bread wheat.

Singh A, Kumar A. Unlocking the potential of ancient hexaploid Indian dwarf wheat, Tritium sphaerococcum for grain quality improvement

Wild and ancient wheat are considered to be a rich source of nutrients and better stress tolerant, hence being re-considered for mainstreaming its cultivation by the farmers and bringing it back to the food basket. In the present study, thirty-four diverse accessions of Indian dwarf wheat, Triticum sphaerococcum conserved in the Indian National Genebank were evaluated for thirteen-grain quality parameters namely thousand-grain weight (TGW), hectolitre weight (HW), sedimentation value (Sed), grain hardness index (HI), protein (Pro), albumin (Alb), globulin (Glo), gliadin (Gli), glutenin (Glu), gluten, lysine (Lys), Fe²⁺ and Zn²⁺ content, and four antioxidant enzymes activities. Substantial variations were recorded for studied traits. TGW, HW, Sed, HI, Pro, Alb, Glo, Gli, Glu, Gluten, Lys, Fe²⁺, and Zn²⁺ varied from 26.50-45.55 g, 70.50-86.00 kg/hl, 24.00-38.00 ml, 40.49-104.90, 15.34-19.35%, 17.60-40.31 mg/g, 10.75-16.56 mg/g, 26.35-44.94 mg/g, 24.47-39.56 mg/g, 55.33-75.06 mg/g, 0.04-0.29%, 42.72-90.72 ppm, and 11.45-25.70 ppm, respectively. Among antioxidants, peroxidase (POX), catalase (CAT), glutathione reductase (GR), and superoxide dismutase (SOD) activity ranged from 0.06-0.60 unit/ml, 0.02-0.61 unit/ml, 0.11-2.26 unit/ml, and 0.14-0.97 unit/ml, respectively. Hardness Index was positively associated with Pro and Zn²⁺ content whereas Lys was negatively associated with gluten content. Likewise, gluten and Fe²⁺ content had a positive association with the major protein fraction i.e., Gli and Glu. Hierarchical cluster analysis grouped 34 accessions into four clusters and the major group had nine indigenous and eight exotic accessions. We also validated high GPC accessions and EC182958 (17.16%), EC187176 and EC182945 (16.16%), EC613057 (15.79%), IC634028 (15.72%) and IC533826 (15.01%) were confirmed with more than 15% GPC. Also, superior trait-specific accessions namely, EC187167, IC534021, EC613055, EC180066, and EC182959 for low gluten content and IC384530, EC313761, EC180063, IC397363, EC10494 for high iron content (>76.51) were identified that may be used in wheat quality improvement for nutritional security of mankind.

Phenolic Content and Antioxidant Capacity of Synthetic Hexaploid Wheats

In this study, 21 synthetic hexaploid wheat samples were analyzed and compared for phenolic content (the Folin-Ciocalteu method), phenolic compositions, and antioxidant activity (DPPH, ABTS, and CUPRAC). The aim of the study was to determine the phenolic content and antioxidant activity of synthetic wheat lines developed from Ae. Tauschii, which has a wide genetic diversity, to be used in breeding programs for developing new varieties with better nutritional properties. Bound, free, and total phenolic contents (TPCs) of wheat samples were determined as 145.38-258.55 mg GAE/100 g wheat, 188.19-369.38 mg GAE/100 g wheat, and 333.58-576.93 mg GAE/100 g wheat, respectively. Phenolic compositions were detected by the HPLC system. Gallic acid was found in the highest concentrations in free fractions, whereas gallic, p-coumaric acid, and chlorogenic acid were generally found in the highest concentrations in bound fractions of the synthetic hexaploid wheat samples. The antioxidant activities (AA%) of the wheat samples were evaluated by the DPPH assay. AA% in the free extracts of the synthetic red wheat samples ranged from 33.0% to 40.5%, and AA% values in the bound extracts of the synthetic hexaploid wheat samples varied between 34.4% and 50.6%. ABTS and CUPRAC analyses were also used to measure antioxidant activities. The ABTS values of the free and bound extracts and total ABTS values of the synthetic wheat samples ranged from 27.31 to 123.18, 61.65 to 263.23, and 93.94 to 308.07 mg TE/100 g, respectively. The corresponding CUPRAC values of the synthetic wheats were between 25.78-160.94, 75.35-308.13, and 107.51-364.79 mg TE/100 g. This study revealed that synthetic hexaploid wheat samples are valuable resources for breeding programs for developing new wheat varieties with higher concentrations and better compositions of health-beneficial phytochemicals. The samples w1 (Ukr.-Od. 1530.94/Ae. squarrosa (629)), w18 (Ukr.-Od. 1530.94/Ae. squarrosa (1027)), and w20 (Ukr.-Od. 1530.94/Ae. squarrosa (392)) can be used as a genetic resource in breeding programs to enhance the nutritional quality of wheat.

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.

Reference proteomes of five wheat species as starting point for future design of cultivars with lower allergenic potential

Wheat is an important staple food and its processing quality is largely driven by proteins. However, there is a sizable number of people with inflammatory reactions to wheat proteins, namely celiac disease, wheat allergy and the syndrome of non-celiac wheat sensitivity. Thus, proteome profiles should be of high importance for stakeholders along the wheat supply chain. We applied liquid chromatography-tandem mass spectrometry-based proteomics to establish the flour reference proteome for five wheat species, ancient to modern, each based on 10 cultivars grown in three diverse environments. We identified at least 2540 proteins in each species and a cluster analyses clearly separated the species based on their proteome profiles. Even more, >50% of proteins significantly differed between species - many of them implicated in products' quality, grain-starch synthesis, plant stress regulation and proven or potential allergic reactions in humans. Notably, the expression of several important wheat proteins was found to be mainly driven by genetics vs. environmental factors, which enables selection and refinement of improved cultivars for the wheat supply chain as long as rapid test methods will be developed. Especially einkorn expressed 5.4 and 7.2-fold lower quantities of potential allergens and immunogenic amylase trypsin inhibitors, respectively, than common wheat, whereas potential allergen content was intermediate in tetraploid wheat species. This urgently warrants well-targeted clinical studies, where the developed reference proteomes will help to design representative test diets.

Evolution and origin of bread wheat

Bread wheat (Triticum aestivum, genome BBAADD) is a young hexaploid species formed only 8,500-9,000 years ago through hybridization between a domesticated free-threshing tetraploid progenitor, genome BBAA, and Aegilops tauschii, the diploid donor of the D subgenome. Very soon after its formation, it spread globally from its cradle in the fertile crescent into new habitats and climates, to become a staple food of humanity. This extraordinary global expansion was probably enabled by allopolyploidy that accelerated genetic novelty through the acquisition of new traits, new intergenomic interactions, and buffering of mutations, and by the attractiveness of bread wheat's large, tasty, and nutritious grain with high baking quality. New genome sequences suggest that the elusive donor of the B subgenome is a distinct (unknown or extinct) species rather than a mosaic genome. We discuss the origin of the diploid and tetraploid progenitors of bread wheat and the conflicting genetic and archaeological evidence on where it was formed and which species was its free-threshing tetraploid progenitor. Wheat experienced many environmental changes throughout its evolution, therefore, while it might adapt to current climatic changes, efforts are needed to better use and conserve the vast gene pool of wheat biodiversity on which our food security depends.