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1.
Improvement and Re-Evolution of Tetraploid Wheat for Global Environmental Challenge and Diversity Consumption Demand.
Yang, F, Zhang, J, Liu, Q, Liu, H, Zhou, Y, Yang, W, Ma, W
International journal of molecular sciences. 2022;(4)
Abstract
Allotetraploid durum wheat is the second most widely cultivated wheat, following hexaploid bread wheat, and is one of the major protein and calorie sources of the human diet. However, durum wheat is encountered with a severe grain yield bottleneck due to the erosion of genetic diversity stemming from long-term domestication and especially modern breeding programs. The improvement of yield and grain quality of durum wheat is crucial when confronted with the increasing global population, changing climate environments, and the non-ignorable increasing incidence of wheat-related disorders. This review summarized the domestication and evolution process and discussed the durum wheat re-evolution attempts performed by global researchers using diploid einkorn, tetraploid emmer wheat, hexaploid wheat (particularly the D-subgenome), etc. In addition, the re-evolution of durum wheat would be promoted by the genetic enrichment process, which could diversify allelic combinations through enhancing chromosome recombination (pentaploid hybridization or pairing of homologous chromosomes gene Ph mutant line induced homoeologous recombination) and environmental adaptability via alien introgressive genes (wide cross or distant hybridization followed by embryo rescue), and modifying target genes or traits by molecular approaches, such as CRISPR/Cas9 or RNA interference (RNAi). A brief discussion of the future perspectives for exploring germplasm for the modern improvement and re-evolution of durum wheat is included.
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2.
Creation and judicious application of a wheat resistance gene atlas.
Hafeez, AN, Arora, S, Ghosh, S, Gilbert, D, Bowden, RL, Wulff, BBH
Molecular plant. 2021;(7):1053-1070
Abstract
Disease-resistance (R) gene cloning in wheat (Triticum aestivum) has been accelerated by the recent surge of genomic resources, facilitated by advances in sequencing technologies and bioinformatics. However, with the challenges of population growth and climate change, it is vital not only to clone and functionally characterize a few handfuls of R genes, but also to do so at a scale that would facilitate the breeding and deployment of crops that can recognize the wide range of pathogen effectors that threaten agroecosystems. Pathogen populations are continually changing, and breeders must have tools and resources available to rapidly respond to those changes if we are to safeguard our daily bread. To meet this challenge, we propose the creation of a wheat R-gene atlas by an international community of researchers and breeders. The atlas would consist of an online directory from which sources of resistance could be identified and deployed to achieve more durable resistance to the major wheat pathogens, such as wheat rusts, blotch diseases, powdery mildew, and wheat blast. We present a costed proposal detailing how the interacting molecular components governing disease resistance could be captured from both the host and the pathogen through biparental mapping, mutational genomics, and whole-genome association genetics. We explore options for the configuration and genotyping of diversity panels of hexaploid and tetraploid wheat, as well as their wild relatives and major pathogens, and discuss how the atlas could inform a dynamic, durable approach to R-gene deployment. Set against the current magnitude of wheat yield losses worldwide, recently estimated at 21%, this endeavor presents one route for bringing R genes from the lab to the field at a considerable speed and quantity.
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3.
Molecular Mapping and Genomics of Grain Yield in Durum Wheat: A Review.
Arriagada, O, Marcotuli, I, Gadaleta, A, Schwember, AR
International journal of molecular sciences. 2020;(19)
Abstract
Durum wheat is the most relevant cereal for the whole of Mediterranean agriculture, due to its intrinsic adaptation to dryland and semi-arid environments and to its strong historical cultivation tradition. It is not only relevant for the primary production sector, but also for the food industry chains associated with it. In Mediterranean environments, wheat is mostly grown under rainfed conditions and the crop is frequently exposed to environmental stresses, with high temperatures and water scarcity especially during the grain filling period. For these reasons, and due to recurrent disease epidemics, Mediterranean wheat productivity often remains under potential levels. Many studies, using both linkage analysis (LA) and a genome-wide association study (GWAS), have identified the genomic regions controlling the grain yield and the associated markers that can be used for marker-assisted selection (MAS) programs. Here, we have summarized all the current studies identifying quantitative trait loci (QTLs) and/or candidate genes involved in the main traits linked to grain yield: kernel weight, number of kernels per spike and number of spikes per unit area.
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4.
The Battle to Sequence the Bread Wheat Genome: A Tale of the Three Kingdoms.
Guan, J, Garcia, DF, Zhou, Y, Appels, R, Li, A, Mao, L
Genomics, proteomics & bioinformatics. 2020;(3):221-229
Abstract
In the year 2018, the world witnessed the finale of the race to sequence the genome of the world's most widely grown crop, the common wheat. Wheat has been known to bear a notoriously large and complicated genome of a polyploidy nature. A decade competition to sequence the wheat genome initiated with a single consortium of multiple countries, taking a conventional strategy similar to that for sequencing Arabidopsis and rice, became ferocious over time as both sequencing technologies and genome assembling methodologies advanced. At different stages, multiple versions of genome sequences of the same variety (e.g., Chinese Spring) were produced by several groups with their special strategies. Finally, 16 years after the rice genome was finished and 9 years after that of maize, the wheat research community now possesses its own reference genome. Armed with these genomics tools, wheat will reestablish itself as a model for polyploid plants in studying the mechanisms of polyploidy evolution, domestication, genetic and epigenetic regulation of homoeolog expression, as well as defining its genetic diversity and breeding on the genome level. The enhanced resolution of the wheat genome should also help accelerate development of wheat cultivars that are more tolerant to biotic and/or abiotic stresses with better quality and higher yield.
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5.
The Sulphur Response in Wheat Grain and Its Implications for Acrylamide Formation and Food Safety.
Raffan, S, Oddy, J, Halford, NG
International journal of molecular sciences. 2020;(11)
Abstract
Free (soluble, non-protein) asparagine concentration can increase many-fold in wheat grain in response to sulphur deficiency. This exacerbates a major food safety and regulatory compliance problem for the food industry because free asparagine may be converted to the carcinogenic contaminant, acrylamide, during baking and processing. Here, we describe the predominant route for the conversion of asparagine to acrylamide in the Maillard reaction. The effect of sulphur deficiency and its interaction with nitrogen availability is reviewed, and we reiterate our advice that sulphur should be applied to wheat being grown for human consumption at a rate of 20 kg per hectare. We describe the genetic control of free asparagine accumulation, including genes that encode metabolic enzymes (asparagine synthetase, glutamine synthetase, glutamate synthetase, and asparaginase), regulatory protein kinases (sucrose nonfermenting-1 (SNF1)-related protein kinase-1 (SnRK1) and general control nonderepressible-2 (GCN2)), and basic leucine zipper (bZIP) transcription factors, and how this genetic control responds to sulphur, highlighting the importance of asparagine synthetase-2 (ASN2) expression in the embryo. We show that expression of glutamate-cysteine ligase is reduced in response to sulphur deficiency, probably compromising glutathione synthesis. Finally, we describe unexpected effects of sulphur deficiency on carbon metabolism in the endosperm, with large increases in expression of sucrose synthase-2 (SuSy2) and starch synthases.
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6.
Bread wheat: a role model for plant domestication and breeding.
Venske, E, Dos Santos, RS, Busanello, C, Gustafson, P, Costa de Oliveira, A
Hereditas. 2019;:16
Abstract
BACKGROUND Bread wheat is one of the most important crops in the world. Its domestication coincides with the beginning of agriculture and since then, it has been constantly under selection by humans. Its breeding has followed millennia of cultivation, sometimes with unintended selection on adaptive traits, and later by applying intentional but empirical selective pressures. For more than one century, wheat breeding has been based on science, and has been constantly evolving due to on farm agronomy and breeding program improvements. The aim of this work is to briefly review wheat breeding, with emphasis on the current advances. DISCUSSION Improving yield potential, resistance/tolerance to biotic and abiotic stresses, and baking quality, have been priorities for breeding this cereal, however, new objectives are arising, such as biofortification enhancement. The narrow genetic diversity and complexity of its genome have hampered the breeding progress and the application of biotechnology. Old approaches, such as the introgression from relative species, mutagenesis, and hybrid breeding are strongly reappearing, motivated by an accumulation of knowledge and new technologies. A revolution has taken place regarding the use of molecular markers whereby thousands of plants can be routinely genotyped for thousands of loci. After 13 years, the wheat reference genome sequence and annotation has finally been completed, and is currently available to the scientific community. Transgenics, an unusual approach for wheat improvement, still represents a potential tool, however it is being replaced by gene editing, whose technology along with genomic selection, speed breeding, and high-throughput phenotyping make up the most recent frontiers for future wheat improvement. FINAL CONSIDERATION Agriculture and plant breeding are constantly evolving, wheat has played a major role in these processes and will continue through decades to come.
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7.
Next-Generation Sequencing Promoted the Release of Reference Genomes and Discovered Genome Evolution in Cereal Crops.
Huang, Y, Liu, H, Xing, Y
Current issues in molecular biology. 2018;:37-50
Abstract
In recent decades, next-generation sequencing (NGS) was developed and brought biology into a new era. Rice, maize, wheat, sorghum and barley are the most important cereal crops and feed most of the world's population. Great progress in the study of cereal genomes has been made with the help of NGS. Reference genome sequence assembly and re-sequencing have grown exponentially. Thus, evolution and comparative genomics are renewed, including origin verification, evolution tracking and so on. In this review, we briefly record the development of sequencing technology, the comparison of next-generation sequencing methods and platforms and summarize the bioinformatics tools used for NGS data analysis. We describe how NGS accelerates reference genome assembly and new evolutionary findings. We finally discuss how to discover more valuable resources and improve cereal breeding in the future.
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8.
A review of wheat diseases-a field perspective.
Figueroa, M, Hammond-Kosack, KE, Solomon, PS
Molecular plant pathology. 2018;(6):1523-1536
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Abstract
Wheat is one of the primary staple foods throughout the planet. Significant yield gains in wheat production over the past 40 years have resulted in a steady balance of supply versus demand. However, predicted global population growth rates and dietary changes mean that substantial yield gains over the next several decades will be needed to meet this escalating demand. A key component to meeting this challenge is better management of fungal incited diseases, which can be responsible for 15%-20% yield losses per annum. Prominent diseases of wheat that currently contribute to these losses include the rusts, blotches and head blight/scab. Other recently emerged or relatively unnoticed diseases, such as wheat blast and spot blotch, respectively, also threaten grain production. This review seeks to provide an overview of the impact, distribution and management strategies of these diseases. In addition, the biology of the pathogens and the molecular basis of their interaction with wheat are discussed.
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9.
Clinical application of dietary therapies in irritable bowel syndrome.
Rej, A, Avery, A, Ford, AC, Holdoway, A, Kurien, M, McKenzie, Y, Thompson, J, Trott, N, Whelan, K, Williams, M, et al
Journal of gastrointestinal and liver diseases : JGLD. 2018;(3):307-316
Abstract
BACKGROUND AND AIMS Diet appears to play a pivotal role in symptom generation in Irritable Bowel Syndrome (IBS). First line dietary therapy for IBS has focused on advice concerning healthy eating and lifestyle management. Research recently has focused on the role of a diet low in fermentable oligo-, di-, and mono-saccharides and polyols (FODMAPs), gluten free (GFD) and wheat free (WFD) diets for the relief of symptoms in IBS. METHODS A round table discussion with gastroenterologists and dietitians with a specialist interest in dietary therapies in IBS was held in Sheffield, United Kingdom in May 2017. Existing literature was reviewed. PubMed and EMBASE were searched with the MeSH terms irritable bowel syndrome/diet/diet therapy/gluten/low FODMAP in different combinations to identify relevant articles. A consensus on the application of these dietary therapies into day-to-day practice was developed. RESULTS Fourteen randomized trials in IBS evaluating the low FODMAP diet (n studies = 9), GFD (n = 4) and WFD (n = 1) were included in this review. The total number of patients recruited from randomized trials reviewed was: n=580 low FODMAP diet (female, n=430), n=203 GFD (female, n=139), n=276 WFD (female, n=215). There was no significant difference in the gender of patients recruited for both the low FODMAP and GFD randomized studies (p=0.12). The response rate in the literature to a low FODMAP diet ranged between 50-76%, and to GFD ranged between 34-71%. Percentage of IBS patients identified as wheat sensitive was reported as 30% in the literature. CONCLUSION There are no head-to-head trials to date utilizing the low FODMAP diet, GFD and WFD for dietary treatment of IBS and still a number of concerns for diets, including nutritional inadequacy and alteration of the gut microbiota. The consensus suggests that there is evidence for the use of the low FODMAP diet, GFD and WFD as dietary therapies for IBS; the decision-making process for using each individual therapy should be directed by a detailed history by the dietitian, involving the patient in the process.
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10.
What Do We Know Now about IgE-Mediated Wheat Allergy in Children?
Czaja-Bulsa, G, Bulsa, M
Nutrients. 2017;(1)
Abstract
IgE-mediated wheat allergy is a gluten-related disorder. Wheat is one of the five most common food allergens in children. However, the natural history of IgE-mediated wheat allergy has seldom been described in the research literature. This study presents the current state of knowledge about the IgE-mediated wheat allergy in children.