'GoWheat 9216H' (Reg. no. CV-1224, PI 708101) is a hard red winter wheat (Triticum aestivum L.) that was bred and released by the Texas A&M AgriLife Research Wheat Improvement Program in 2021. GoWheat 9216H is an F4-derived line advanced from the cross 'X09A440S' ( = TX07A001482/TAM 401)/'Duster' that was made in Bushland, TX, in 2010. GoWheat 9216H is a medium-maturing, semi-dwarf, awned and white glumed wheat that has demonstrated high grain yield potential across many Texas environments in both irrigated and dryland conditions. GoWheat 9216H is resistant to stem rust (Sr; Puccinia graminis Pers.:Pers f. sp. tritici Erikss. & E. Henn.), leaf rust (Lr; P. triticina Erikss.), and stripe rust (Yr; P. striiformis Westend. f. sp. tritici Erikss.), with marker data suggesting it carries Lr34, Lr37, Lr68, Yr17, Yr18, YrM1225, and Sr38. It is moderately resistant to Hessian fly [Mayetiola destructor (Say)]. This cultivar shows good baking and milling quality traits equivalent to high-quality checks and further features large seeds and high grain volume weight. Its height is similar to that of recently released Texas A&M cultivars, but it has a later maturity date. GoWheat 9216H is poised to perform well under both irrigated and dryland conditions in the Texas Rolling Plains, South and Central Texas, and the Blacklands, as well as in other regions across the state with similar adaptation zones.

Leaf rust (Puccinia triticina) and stripe rust (Puccinia striiformis f. sp. tritici) are among the most prevalent foliar diseases in wheat, causing significant annual yield losses worldwide. To identify rust resistance genes in U.S. winter wheat, we conducted a genome-wide association study (GWAS) on resistance to leaf and stripe rusts in U.S. winter wheat cultivars and elite advanced breeding lines. Using simple sequence repeats (SSRs) and wheat 90K single nucleotide polymorphism (SNP) arrays, we identified two novel quantitative trait loci (QTLs), QLr.hwwg-2BL and QLr.hwwg-4AL, and four QTLs corresponding to known genes Lr74, Lr77, Lr18 and Lr68 for leaf rust resistance. We also identified five QTLs conferring stripe rust resistance, which included the three previously characterized loci Yr17/YrM1225 on the 2NS/2AS translocation, Yr30/Sr2 on 3BS, and QYr.hwwg-2BS, along with two putative novel loci, QYr.hwwg-2AS.2 and QYr.hwwg-4BL, with the latter located in a QTL-rich region. The QTLs identified in this study will be useful for improving durable resistance to leaf and stripe rusts in new wheat cultivars using marker-assisted gene-pyramiding strategy.

The GWAS and testing with Yr gene linked markers identified 109 loci including 40 novel loci for all-stage and adult plant stage resistance to stripe rust in 459 US contemporary hard winter wheat genotypes. Stripe rust is a destructive wheat disease, caused by Puccinia striiformis f. sp. tritici (Pst). To identify sources of stripe rust resistance in US contemporary hard winter wheat, a panel of 459 Great Plains wheat genotypes was evaluated at the seedling stage against five US Pst races and at the adult plant stage in field environments in Oklahoma, Kansas, and Washington. The results showed that 7–14

Leaf rust, caused by Puccinia triticina (Pt), is a serious constraint to wheat production. Developing resistant varieties is the best approach to managing this disease. Wheat leaf rust resistance (Lr) genes have been classified into either all-stage resistance (ASR) or adult-plant resistance (APR). The objectives of this study were to identify sources of leaf rust resistance in contemporary US hard winter wheat (HWW) and to dissect the genetic basis underlying leaf rust resistance in HWW. A panel of 732 elite HWW genotypes was evaluated for response to US Pt races at the seedling stage and at the adult plant stage in leaf rust nurseries in Oklahoma, Texas, and Kansas. Further, the panel was genotyped using multiplex restriction amplicon sequencing (MRA-Seq) and DNA markers linked to the known ASR genes Lr18, Lr19, Lr21, Lr24, Lr37, and Lr42 and APR genes Lr34, Lr46, Lr67, Lr68, Lr77, and Lr78. Single nucleotide polymorphism (SNP) markers derived from MRA-Seq, DNA markers linked to the known Lr genes, and the phenotypic data were used for genome-wide association study (GWAS) to identify markers associated with leaf rust response. Gene postulation based on leaf rust reactions, DNA markers, and GWAS suggested the presence of Lr1, Lr2a, Lr10, Lr14a, Lr16, Lr18, Lr19, Lr21, Lr24, Lr26, Lr34, Lr37, Lr39, Lr42, Lr46, Lr68, Lr77, and Lr78 in the HWW panel. The GWAS identified 59 SNPs significantly associated with leaf rust response, of which 20 were likely associated with novel resistance loci and can be used to enhance wheat leaf rust resistance.

'KS Big Bow' (Reg. no. CV-1206, PI 701521), a hard white winter wheat (Triticum aestivum L.) cultivar, was developed by the wheat breeding program at the Agricultural Research Center-Hays, Kansas State University, and released by the Kansas Agricultural Experiment Station in 2022. KS Big Bow was selected from a single cross of KS050223M-2/KS11HW15 using a modified bulk breeding method. The main objective of this cross is to release a competitive hard white winter wheat cultivar with adaptation to the dryland production in western Kansas. KS Big Bow is an F5-derived line and was tested in yield trials from 2017 to 2022 in Kansas before its release. It has performed well in dryland yield trials in western Kansas. KS Big Bow has a medium to medium-early maturity and medium plant height. Its test weight and straw strength are good. KS Big Bow has a good disease-resistant package including resistance to Wheat streak mosaic virus, moderate resistances to stripe rust (caused by Puccinia striiformis Westend. f. sp. tritici Erikss.) and stem rust (caused by P. graminis Pers f. sp. tritici Eriks. & E. Henn.), and intermediate resistance to Barley yellow dwarf virus. Its milling and baking qualities are about average. KS Big Bow is a newly released hard white winter wheat cultivar for western Kansas.KS Big Bow has high yield potential.KS Big Bow has good disease resistance, including Wheat streak mosaic virus, stripe rust, and stem rust.

In many regions worldwide wheat (Triticum aestivum L.) plants experience terminal high temperature stress during the grain filling stage, which is a leading cause for single seed weight decrease and consequently for grain yield reduction. An approach to mitigate high temperature damage is to develop tolerant cultivars using the conventional breeding approach which involves identifying tolerant lines and then incorporating the tolerant traits in commercial varieties. In this study, we evaluated the terminal heat stress tolerance of 304 diverse elite winter wheat lines from wheat breeding programs in the US, Australia, and Serbia in controlled environmental conditions. Chlorophyll content and yield traits were measured and calculated as the percentage of non-stress control. The results showed that there was significant genetic variation for chlorophyll retention and seed weight under heat stress conditions. The positive correlation between the percent of chlorophyll content and the percent of single seed weight was significant. Two possible mechanisms of heat tolerance during grain filling were proposed. One represented by wheat line OK05723W might be mainly through the current photosynthesis since the high percentage of single seed weight was accompanied with high percentages of chlorophyll content and high shoot dry weight, and the other represented by wheat Line TX04M410164 might be mainly through the relocation of reserves since the high percentage of single seed weight was accompanied with low percentages of chlorophyll content and low shoot dry weight under heat stress. The tolerant genotypes identified in this study should be useful for breeding programs after further validation.

Stripe (yellow) rust, caused by Puccinia striiformis f. sp. tritici, is a devastating disease of wheat (Triticum aestivum) worldwide. In commercial production, stripe rust reduces grain quality, grain yield, and forage yield. This study was conducted to identify quantitative trait locus (QTL) associated with field resistance to stripe rust in hard winter wheat. Stripe rust infection type and severity were rated in recombinant inbred lines (RILs, n = 204) derived from a cross between hard red winter wheat cultivars "Overley" and "Overland" in replicated field trials in the Great Plains and Pacific Northwest. RILs (n = 184) were genotyped with reduced representation sequencing to produce single nucleotide polymorphism (SNP) markers from alignment to the "Chinese Spring" reference sequence, IWGSC v2.1, and from alignment to the reference sequence for "Jagger," which is a parent of Overley. Genetic linkage maps were developed independently from each set of SNP markers. QTL analysis identified genomic regions on chromosome arms 2AS, 2BS, 2BL, and 2DL that were associated with stripe rust resistance using multi-environment best linear unbiased predictors for stripe rust infection type and severity. Results for the two linkage maps were very similar. PCR-based SNP marker assays associated with the QTL regions were developed to efficiently identify these genomic regions in breeding populations.

Historically, wheat (Triticum aestivum L.) cultivars developed by the cooperative University of Nebraska-USDA-ARS wheat improvement project were hard red winter wheat. With the expanding hard white wheat market, there is a greater emphasis on developing hard white winter wheat lines adapted to the Great Plains. 'NW13493' (tested as NW13493) (Reg. no. CV-1197, PI 699380) was selected for its white kernels, agronomic performance, relevant disease resistances, and end-use quality and is adapted to the central Great Plains. NW13493 was licensed to Bay State Milling Company on the basis of its superior agronomic and end-use quality performance and also the need to ensure hard white wheat growers have a known market for their grain. NW13493 hard white winter wheat was released in February 2021 by the developing institutions and the licensee. NW13493 was a selection in 2013 from the cross 'SD98W175-1'/'NW03666', which was made in 2007. The pedigree of SD98W175-1 is 'KS84273BB-10'/'KSSB110-9'//'KS831374-141B'/'YE1110'/3/ 'KS82W418'/'Stephens' and the pedigree of NW03666 is 'N94S097KS'/'NE93459'. The F-1 generation was grown in the greenhouse in 2008, and the F-2 to F-3 generations were advanced as bulks at Mead, NE, in 2009-2010. NW13493 was evaluated in replicated trials beginning in 2014. It has excellent winter survival and agronomic performance, acceptable disease reactions to many of the common diseases in its target area, and good end-use quality for bread making.

Next-generation sequencing (NGS) technology advancements continue to reduce the cost of high-throughput genome-wide genotyping for breeding and genetics research. Skim sequencing, which surveys the entire genome at low coverage, has become feasible for quantitative trait locus (QTL) mapping and genomic selection in various crops. However, the genome complexity of allopolyploid crops such as wheat (Triticum aestivum L.) still poses a significant challenge for genome-wide genotyping. Targeted sequencing of the protein-coding regions (i.e., exome) reduces sequencing costs compared to whole genome re-sequencing and can be used for marker discovery and genotyping. We developed a method called skim exome capture (SEC) that combines the strengths of these existing technologies and produces targeted genotyping data while decreasing the cost on a per-sample basis compared to traditional exome capture. Specifically, we fragmented genomic DNA using a tagmentation approach, then enriched those fragments for the low-copy genic portion of the genome using commercial wheat exome baits and multiplexed the sequencing at different levels to achieve desired coverage. We demonstrated that for a library of 48 samples, ∼7-8× target coverage was sufficient for high-quality variant detection. For higher multiplexing levels of 528 and 1056 samples per library, we achieved an average coverage of 0.76× and 0.32×, respectively. Combining these lower coverage SEC sequencing data with genotype imputation using a customized wheat practical haplotype graph database that we developed, we identified hundreds of thousands of high-quality genic variants across the genome. The SEC method can be used for high-resolution QTL mapping, genome-wide association studies, genomic selection, and other downstream applications.

Wheat streak mosaic virus (WSMV) is a mite-vectored virus with substantial economic impact on wheat production. One of the effective sources of resistance to WSMV, Wsm1, is carried on a translocation from Thinopyrum intermedium. The original whole arm form of this translocation (T4DL center dot 4J(s)S) was highly effective against WSMV but carried a substantial yield penalty in the absence of the virus. Shorter recombinants of the Th. intermedium translocation are now available. This study characterized the agronomic performance of near-isogenic sib-pair families in 10 yield trials using one of these shortened T4DL center dot 4DS-4J(s)S translocations, named "rec213," in the absence of visible disease. This translocation had no effect on heading date, was associated with a modest reduction (<= 4.8 cm) in plant height, and the translocation had a favorable effect (<= 12.6%) on grain yield in those environments where highly significant genotype effects were detected. The translocation did not affect protein concentration or lactic acid-sodium dodecyl sulfate solvent retention capacity, a measure of gluten quality. However, families with the translocation had slightly (<= 5%) lower protein quality scores than paired families without the translocation. We do not expect this modest difference in quality to be a barrier to utilization of the rec213 translocation for Wsm1, but we encourage breeders to work within high-quality genetic backgrounds when using the rec213 translocation and to monitor the quality of breeding selections. Improved codominant PCR-based marker assays were developed to facilitate the use of the rec213 Wsm1 trait in breeding programs.

Hard winter wheat (Triticum aestivum L.) is a major crop in semi-arid western Kansas. The objective of this research was to develop a hard red winter wheat cultivar for western Kansas with high grain yield potential, good baking quality, and resistance to the important diseases in this region, including Wheat streak mosaic virus, Barley yellow dwarf virus, stripe rust, leaf rust, stem rust, and Hessian fly. 'KS Hamilton' (Reg. no. CV-1188, PI 699003) hard red winter wheat was developed by the wheat breeding program at the Agricultural Research Center-Hays, Kansas State University, and released by the Kansas Agricultural Experiment Station in 2020. KS Hamilton was selected from a three-way cross of KS08HW176-4//'Bill Brown'/KS08HW61-2. It was released for the dryland production in western Kansas. KS Hamilton was developed using a modified bulk breeding method. KS Hamilton is an F-6-derived line and was tested in yield trials for 6 yr. KS Hamilton has an intermediate maturity and plant height and an average straw strength. It has moderate tolerance to grain shattering and good winterhardiness. KS Hamilton has high grain yield potential in western Kansas and a good disease resistance package, including resistance to Wheat streak mosaic virus, stem rust, and Hessian fly; moderate resistance to Barley yellow dwarf virus; and intermediate resistance to stripe and leaf rusts. KS Hamilton has an average test weight and an above-average baking quality.

High temperature has been a major limiting factor for wheat (Triticum aestivum L.) productivity and will become a significant driver of yield loss as global warming progresses. Many wheat-growing regions worldwide experience terminal heat stress during the grain-filling period, resulting in grain yield reduction. A sustainable solution to mitigate heat stress-induced damage is to develop heat-tolerant cultivars. To achieve this, identifying tolerant lines is essential to incorporate heat stress resilience into commercial varieties. Our working hypothesis was that retaining chlorophyll content during post-flowering heat stress will reduce yield losses. In this study, we evaluated the terminal heat stress tolerance of 254 diverse spring wheat lines from North American and Australian wheat-breeding programs in two independent experiments. The plants were grown in individual pots under controlled environments. Significant genetic variation was observed for the ability to retain post-stress chlorophyll content and yield components. Grain yield per plant and individual grain weight were significantly correlated with chlorophyll content under heat stress. The reduction in grain yield per plant was contributed more by the reduction of the individual grain weight than by the grain number under heat stress. A highly tolerant line, cultivar Otis, retained 79.2% chlorophyll content relative to control, and also recorded 55% greater chlorophyll content than the average of all 254 lines, at the end of 16 d of severe heat stress treatment. Mapping populations are being developed using Otis, with an aim to identify the genetic basis of chlorophyll retention under terminal heat stress. Resilient wheat lines identified with high grain weight under stress will serve as useful resources for abiotic stress breeding programs.

To improve the efficiency of high-density genotype data storage and imputation in bread wheat (Triticum aestivum L.), we applied the Practical Haplotype Graph (PHG) tool. The wheat PHG database was built using whole-exome capture sequencing data from a diverse set of 65 wheat accessions. Population haplotypes were inferred for the reference genome intervals defined by the boundaries of the high-quality gene models. Missing genotypes in the inference panels, composed of wheat cultivars or recombinant inbred lines genotyped by exome capture, genotyping-by-sequencing (GBS), or whole-genome skim-seq sequencing approaches, were imputed using the wheat PHG database. Though imputation accuracy varied depending on the method of sequencing and coverage depth, we found 93% imputation accuracy with 0.01x sequence coverage, which was only slightly lower than the accuracy obtained using the 0.5x sequence coverage (96.9%). Compared to Beagle, on average, PHG imputation was ~4% (p-value = 0.00027) more accurate, and showed 27% higher accuracy at imputing a rare haplotype introgressed from a wild relative into wheat. The reduced accuracy of imputation with GBS data (90.4%) is likely associated with the small overlap between GBS markers and the exome capture dataset, which was used for constructing PHG. The highest imputation accuracy was obtained with exome capture for the wheat D genome, which also showed the highest levels of linkage disequlibrium and proportion of identity-by-descent regions among accessions in our reference panel. We demonstrate that genetic mapping based on genotypes imputed using PHG identifies SNPs with a broader range of effect sizes that together explain a higher proportion of genetic variance for heading date and meiotic crossover rate compared to previous studies.

The wheat wild relative Aegilops tauschii was previously used to transfer the Lr42 leaf rust resistance gene into bread wheat. Lr42 confers resistance at both seedling and adult stages, and it is broadly effective against all leaf rust races tested to date. Lr42 has been used extensively in the CIMMYT international wheat breeding program with resulting cultivars deployed in several countries. Here, using a bulked segregant RNA-Seq (BSR-Seq) mapping strategy, we identify three candidate genes for Lr42. Overexpression of a nucleotide-binding site leucine-rich repeat (NLR) gene AET1Gv20040300 induces strong resistance to leaf rust in wheat and a mutation of the gene disrupted the resistance. The Lr42 resistance allele is rare in Ae. tauschii and likely arose from ectopic recombination. Cloning of Lr42 provides diagnostic markers and over 1000 CIMMYT wheat lines carrying Lr42 have been developed documenting its widespread use and impact in crop improvement.

Historically cultivars developed jointly by the University of Nebraska-Lincoln and USDA-ARS wheat (Triticum aestivum L.) improvement project tend to be late and better adapted to the northern Great Plains. LCS 'Valiant' (Reg. no. CV-1196, PI 693223; tested as NE10478-1) was released based on the merits of its earliness, agronomic performance, relevant disease resistances, and end-use quality characteristics and its adaptation to the central Great Plains. As such, the line was licensed to Limagrain Cereal Seeds for their ability to market outside of Nebraska. LCS Valiant hard red winter wheat was released in March 2020 by the developing institutions and the licensee. NE10478-1 was a selection in 2011 for uniformity and grain yield from NE10478, which was derived from the cross NI03418/'Camelot'. The pedigree of NI03418 is W91-248/NE95544 (=McVey 78015/NE88521)//'Thunderbird'. The final cross of NE10478 was made in 2004. The F-1 generation was grown in Yuma, AZ, in 2005, and the F-2 to F-3 generations were advanced as bulks at Mead, NE, in 2006-2007 or sent for Hessian fly resistance screening by the USDA. In 2007, single F-3-derived F-4 rows were planted for selection. There was no further selection in NE10478 other than to remove off-types thereafter until 2011 when heads were selected to increase uniformity. LCS Valiant was evaluated in replicated trials thereafter. It has excellent winter survival, acceptable reactions to many of the common diseases in its target area, and good end-use quality for bread making.

Puccinia graminis f.sp. tritici (Pgt) causes stem rust disease in wheat that can result in severe yield losses. The factors driving the evolution of its virulence and adaptation remain poorly characterized. We utilize long-read sequencing to develop a haplotype-resolved genome assembly of a U.S. isolate of Pgt. Using Pgt haplotypes as a reference, we characterize the structural variants (SVs) and single nucleotide polymorphisms in a diverse panel of isolates. SVs impact the repertoire of predicted effectors, secreted proteins involved in host-pathogen interaction, and show evidence of purifying selection. By analyzing global and local genomic ancestry we demonstrate that the origin of 8 out of 12 Pgt clades is linked with either somatic hybridization or sexual recombination between the diverged donor populations. Our study shows that SVs and admixture events appear to play an important role in broadening Pgt virulence and the origin of highly virulent races, creating a resource for studying the evolution of Pgt virulence and preventing future epidemic outbreaks.

Cornerstone cultivars earn their status as much by their genetic fortitude and successive progeny as by their own visibility. 'Duster' hard red winter (HRW) wheat (Triticum aestivum L.) established a foundation of yield potential, pest resistance, and baking quality on which two half-sib progenies named 'Gallagher' (Reg. no. CV-1177, PI 667569) and 'Iba' (Reg. no. CV-1178, PI 667570) were released by the Oklahoma Agricultural Experiment Station in 2012 and subsequently assumed significant commercial hectares in the U.S. southern plains. Our objectives were to characterize and compare Gallagher and Iba with their parent Duster for a wide array of agronomic, end-use quality, and wheat sensitivity traits. Bulked descendants of sister F-4:5 lines, Gallagher and Iba were tested as experimental lines OK07214 and OK07209, respectively. In one breeding cycle, they showed an 8% yield gain in grain-only environments, with 10-17% increases in kernel weight, divergent wheat protein responses, unidirectional responses in total fructan content, and wide bidirectional responses in flour levels of immunotoxic gluten epitopes. Both cultivars remain excellent sources of yield potential and functionality, yet their ultimate adoption histories did not align with institutional expectations at the time of release. This retrospective analysis provides a non-abstract reminder worthwhile for any agent of wheat improvement: wheat producers may exercise cultivar choice on seemingly modest characteristics but with yield-equivalent precedence.