Carlos Guzmán

Genomic Selection for Processing and End-Use Quality Traits in the CIMMYT Spring Bread Wheat Breeding Program

Genomic selection applied for wheat quality in CIMMYT spring bread wheat breeding program. All wheat quality traits predicted and validated using forward genomic selection. Dough and loaf traits have moderately high predictive ability in CIMMYT breeding program. Genomic selection genetic gain 1.4 to 2.7 times higher than phenotypic selection.

Genomic Prediction of Gene Bank Wheat Landraces

This study examines genomic prediction within 8416 Mexican landrace accessions and 2403 Iranian landrace accessions stored in gene banks. The Mexican and Iranian collections were evaluated in separate field trials, including an optimum environment for several traits, and in two separate environments (drought, D and heat, H) for the highly heritable traits, days to heading (DTH), and days to maturity (DTM). Analyses accounting and not accounting for population structure were performed. Genomic prediction models include genotype × environment interaction (G × E). Two alternative prediction strategies were studied: (1) random cross-validation of the data in 20% training (TRN) and 80% testing (TST) (TRN20-TST80) sets, and (2) two types of core sets, “diversity” and “prediction”, including 10% and 20%, respectively, of the total collections. Accounting for population structure decreased prediction accuracy by 15–20% as compared to prediction accuracy obtained when not accounting for population structure. Accounting for population structure gave prediction accuracies for traits evaluated in one environment for TRN20-TST80 that ranged from 0.407 to 0.677 for Mexican landraces, and from 0.166 to 0.662 for Iranian landraces. Prediction accuracy of the 20% diversity core set was similar to accuracies obtained for TRN20-TST80, ranging from 0.412 to 0.654 for Mexican landraces, and from 0.182 to 0.647 for Iranian landraces. The predictive core set gave similar prediction accuracy as the diversity core set for Mexican collections, but slightly lower for Iranian collections. Prediction accuracy when incorporating G × E for DTH and DTM for Mexican landraces for TRN20-TST80 was around 0.60, which is greater than without the G × E term. For Iranian landraces, accuracies were 0.55 for the G × E model with TRN20-TST80. Results show promising prediction accuracies for potential use in germplasm enhancement and rapid introgression of exotic germplasm into elite materials.

Harnessing Diversity in Wheat to Enhance Grain Yield, Climate Resilience, Disease and Insect Pest Resistance and Nutrition Through Conventional and Modern Breeding Approaches

Current trends in population growth and consumption patterns continue to increase the demand for wheat, a key cereal for global food security. Further, multiple abiotic challenges due to climate change and evolving pathogen and pests pose a major concern for increasing wheat production globally. Triticeae species comprising of primary, secondary, and tertiary gene pools represent a rich source of genetic diversity in wheat. The conventional breeding strategies of direct hybridization, backcrossing and selection have successfully introgressed a number of desirable traits associated with grain yield, adaptation to abiotic stresses, disease resistance, and bio-fortification of wheat varieties. However, it is time consuming to incorporate genes conferring tolerance/resistance to multiple stresses in a single wheat variety by conventional approaches due to limitations in screening methods and the lower probabilities of combining desirable alleles. Efforts on developing innovative breeding strategies, novel tools and utilizing genetic diversity for new genes/alleles are essential to improve productivity, reduce vulnerability to diseases and pests and enhance nutritional quality. New technologies of high-throughput phenotyping, genome sequencing and genomic selection are promising approaches to maximize progeny screening and selection to accelerate the genetic gains in breeding more productive varieties. Use of cisgenic techniques to transfer beneficial alleles and their combinations within related species also offer great promise especially to achieve durable rust resistance.

Wheat quality improvement at CIMMYT and the use of genomic selection on it

The International Center for Maize and Wheat Improvement (CIMMYT) leads the Global Wheat Program, whose main objective is to increase the productivity of wheat cropping systems to reduce poverty in developing countries. The priorities of the program are high grain yield, disease resistance, tolerance to abiotic stresses (drought and heat), and desirable quality. The Wheat Chemistry and Quality Laboratory has been continuously evolving to be able to analyze the largest number of samples possible, in the shortest time, at lowest cost, in order to deliver data on diverse quality traits on time to the breeders for making selections for advancement in the breeding pipeline. The participation of wheat quality analysis/selection is carried out in two stages of the breeding process: evaluation of the parental lines for new crosses and advanced lines in preliminary and elite yield trials. Thousands of lines are analyzed which requires a big investment in resources. Genomic selection has been proposed to assist in selecting for quality and other traits in breeding programs. Genomic selection can predict quantitative traits and is applicable to multiple quantitative traits in a breeding pipeline by attaining historical phenotypes and adding high-density genotypic information. Due to advances in sequencing technology, genome-wide single nucleotide polymorphism markers are available through genotyping-by-sequencing at a cost conducive to application for genomic selection. At CIMMYT, genomic selection has been applied to predict all of the processing and end-use quality traits regularly tested in the spring wheat breeding program. These traits have variable levels of prediction accuracy, however, they demonstrated that most expensive traits, dough rheology and baking final product, can be predicted with a high degree of confidence. Currently it is being explored how to combine both phenotypic and genomic selection to make more efficient the genetic improvement for quality traits at CIMMYT spring wheat breeding program.

Sources of the highly expressed wheat bread making (wbm) gene in CIMMYT spring wheat germplasm and its effect on processing and bread-making quality

Bread-making quality is a core trait for wheat breeding programs. Recently, the expression of a novel gene named wheat bread making (wbm) gene has been associated with good bread-making quality. In this study, 54 historical and modern bread wheat genotypes from CIMMYT were screened by PCR marker for the presence of the allele associated with high wbm expression. Eight of the 54 wheat genotypes tested positive for the wbm allele and the genotype Waxwing was identified as the most likely donor of the allele in part of CIMMYT germplasm. The wbm allele had a significant effect on overall gluten quality, gluten strength, gluten extensibility and bread-making quality, although its effect was smaller than the effects of other quality related genes as Glu-D1, Glu-B1 or the negative effect of the 1BL.1RS translocation. The wbm allele was associated with higher values of the traits mentioned but not with higher protein content. The identification of this new wbm gene/protein is a step forward in understanding wheat quality genetic control. Implementation of marker assisted selection in breeding programs to detect the wbm allele is highly recommended.

Strategies for selecting crosses using genomic prediction in two wheat breeding programs

Cross prediction strategies for grain yield and baking quality traits were compared. Crosses for all parent combinations were obtained via genomic prediction models. Mid‐parent selection was similar to accounting for variance when selecting yield. The variance had a larger impact in cross predictions for quality traits.

Molecular characterization of novel LMW-i glutenin subunit genes from Triticum urartu Thum. ex Gandil.

Key messageA high level of genetic diversity was found in LMW-i genes from Triticum urartu, resulting in detection of 11 novel alleles. The variability detected could affect gluten quality.AbstractLow-molecular weight glutenin subunits are important in determining the viscoelastic properties of wheat dough. Triticum urartu Thum. ex Gandil., which is related to the A genome of polyploid wheat, has been shown as a good source of variation for these subunits. The present study evaluated the variability of LMW-i genes in this species. High polymorphism was found in the sequences analysed and resulted in the detection of 11 novel alleles, classified into two sets (Group-I and -II) showing unique SNPs and InDels. Both groups were associated with Glu-A3-1 genes from common wheat. In general, deduced proteins from Group-II genes possessed a higher proportion of glutamine and proline, which has been previously suggested to be related with good quality. Moreover, there were other changes compared to common wheat. This novel variation could affect dough quality. Additional epitopes for celiac disease were also detected, suggesting that these subunits could be highly reactive. The results showed that T. urartu could be an important source of genetic variability for LMW-i genes that could enlarge the genetic pool of modern wheat.

Genetic impact of Rht dwarfing genes on grain micronutrients concentration in wheat.

Highlights • The Rht dwarfing genes decreased micronutrient concentrations, however, the magnitude depends on the genetic background.• There was a negative effect on kernel weight indicating that Rht genes increased the number of kernels per spike as well as kernels per unit area.• Highly significant positive correlation between the micronutrients; rate of reductions differs in different genetic background.

Molecular Marker-Based Selection Tools in Spring Bread Wheat Improvement: CIMMYT Experience and Prospects

Wheat is a staple food for the major part of the world’s population. For wheat and other crops, it is generally agreed that in order to meet future challenges in food production, multifaceted breeding approaches are needed, including the use of current available genomics resources. Since more than three decades, molecular markers have acted as a versatile genomics tool for fast and unambiguous genetic analysis of plant species of both diploid and polyploid origin. Together with decreasing marker assay costs and interconnected genotyping service facilities, the opportunity to apply marker-assisted selection (MAS) strategies is becoming accessible to more and more breeding programs. We describe the use of molecular markers in wheat breeding with emphasis on the status of MAS in the CIMMYT global wheat program and will share our experience on recently developed prediction methods using genome-wide markers to archive genetic gain for more complex traits.

CIMMYT Series on Carbohydrates, Wheat, Grains, and Health: Wheat-Based Foods: Their Global and Regional Importance in the Food Supply, Nutrition, and Health1,2

Meeting the growing demand for food over the next 20–30 years will be challenging, mainly because the fastest population growth is occurring in already highly populated developing countries and because producing cereal crops (the main source of nutrients in these countries) requires that serious production constraints, due mainly to the effects of climate change, be overcome. Wheat supplies the most calories and proteins to the global population in the form of diverse wheat-based foods. Wheat-based foods are staples that are major sources of micronutrients that are fundamental for normal development, as well as metabolic and cognitive functioning, from childhood to adulthood. Furthermore, whole grain, wheat-based foods have potential additional health benefits because they contribute fiber and bioactive compounds that can help reduce the risk of chronic conditions, such as cardiovascular disease, type 2 diabetes, and other chronic conditions. In this article, we describe common wheat-based foods consumed ...