Hard Red Winter Wheat Cultivars Research Articles

Mapping the quantitative field resistance to stripe rust in a hard winter wheat population “Overley” × “Overland”

AbstractStripe (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.

Fungicide Efficacy on Fusarium Head Blight of Hard Red Winter Wheat in Parsons, KS

In 2022, a field experiment was conducted to investigate the efficacy of fungicide programs on Fusarium head blight (FHB) and deoxynivalenol (DON) levels. Fungicide treatments were evaluated in plots of the hard red winter wheat cultivar ‘KanMark’ inoculated with Fusarium graminearum in Parsons, KS. Treatments consisted of a single application of Prosaro, Caramba, Miravis Ace, Prosaro Pro, or Sphaerex at early anthesis (Feekes 10.5.1), or dual application of Miravis Ace at early anthesis followed by (fb) Prosaro Pro, Sphaerex, or Folicur at 4 days after early anthesis. All fungicide programs numerically reduced FHB visual symptoms and resulted in increased yield compared to the untreated check, although differences were not statistically significant in all cases. The double application treatments (Miravis Ace fb Prosaro Pro, and Miravis Ace fb Spharex) resulted in the highest increase in test weight. Miravis Ace applied at early anthesis fb Prosaro Pro applied at 4 days after early anthesis resulted in the lowest DON levels (79% less than the untreated check).

Durum wheat Teosinte Branched1 null mutations increase tillering

AbstractWheat (Triticum spp.) yield is increased by either producing and testing variants of yield‐limiting genes or crossing to create new allelic combinations. Tiller number and seeds per tiller influence wheat yield, and both are impacted by the Teosinte Branched1 (TB1) gene. We screened 16 hard red spring wheat (Triticum aestivum L.) cultivars, 15 hard red winter wheat cultivars and lines, and 10 durum wheat [Triticum turgidum L. subsp. durum (Desf.) van Slageren] cultivars and lines commonly grown in Montana and found several previously reported TB1 missense alleles along with one new silent and a missense TB1‐A1 allele among the 16 hard red spring wheat cultivars but no TB1 null alleles. Among the 10 durum cultivars, five carried a TB1‐B1‐S184G missense allele and all winter wheat cultivars carried wild‐type TB1 alleles. To determine the impact of TB1 null alleles, this study examined durum wheat genotypes varying for TB1 null alleles created by ethyl methanesulfonate (EMS) mutagenesis. The goal was to determine the impact of TB1 null alleles on tillering, agronomic, and seed traits. The impact of TB1 null alleles was studied alone and together in field trials. The TB1 single‐ and double‐null mutants produced up to 15% more tillers and 18% with positive trends toward increased plant biomass. The results of this research demonstrate that the integration of EMS‐derived TB1 null alleles may prove useful in increasing small‐grain tillering to optimize plant biomass and yield under different growing conditions.

AAC Coldfront hard red winter wheat

AAC Coldfront is a hard red winter wheat (Triticum aestivum L.) cultivar with broad adaptation and excellent performance in all production areas of western Canada. Eligible for grades of Canada Western Red Winter (CWRW) wheat, AAC Coldfront was evaluated in the Western Canadian Winter Wheat Cooperative registration trials relative to CDC Buteo, Emerson, Moats, and AAC Elevate. Based on 32 replicated trials over 3 years (2017/2018–2019/2020), AAC Coldfront produced significantly more grain than all of the checks (108–115%) at a protein concentration similar to the check mean, suggesting an improved capacity to convert soil moisture and nutrients into grain under a wide range of western Canadian field conditions. AAC Coldfront expressed very good winter survival, medium to late maturity, short to moderate height, excellent lodging resistance, and high test weight. AAC Coldfront was rated resistant to stem, leaf, and stripe rust, intermediate in resistance to Fusarium head blight, and susceptible to common bunt. It became a check for western Canadian winter wheat registration trials in 2021/2022.

Registration of ‘Hardy 2519’ wheat

Abstract‘Hardy 2519’ (Reg. no. CV‐1189, PI 692613), a hard red winter (HRW) wheat (Triticum aestivum L.) cultivar, was derived from the cross VA06HRW‐108 × ‘Vision 30’ (PI 661153) using a modified bulk breeding method. Hardy 2519 was tested as VA14HRW‐25 in replicated yield trials in Virginia (2015–2018) and in the USDA‐ARS Uniform Bread Wheat Trials (2016–2018) and released by the Virginia Agricultural Experiment Station in 2019. Hardy 2519 is a widely adapted, high‐yielding HRW wheat with 2*, 5+10 gluten subunits. Hardy 2519 is awned, semidwarf (Rht 2 gene) with medium spike emergence, resistant to leaf rust, and moderately resistant to powdery mildew in the mid‐Atlantic region. In the Virginia Bread Wheat Elite Trials from 2018 to 2020, Hardy 2519 produced a mean yield of 5,393 kg ha–1, which was similar to that of the HRW wheat cultivar ‘Vision 45’ (PI 667642) at 5,267 kg ha–1. Hardy 2519 has acceptable milling and baking quality on the basis of comparisons with the HRW wheat check cultivar ‘Jagger’.

Effect of Biofertilizer in Organic and Conventional Systems on Growth, Yield and Baking Quality of Hard Red Winter Wheat

A two-year study (harvest years 2019 and 2020) was conducted to investigate the effect of a commercially available biofertilizer, in combination with variable nitrogen (N) rate, on bread baking quality and agronomic traits in hard winter wheat grown in conventional (CONV) and organic (ORG) farming systems in Kentucky, USA. The hard red winter wheat cultivar ‘Vision 45’ was used with three N rates (44, 89.6 and 134.5 kg/ha as Low, Med and High, respectively) and three biofertilizer spray regimes (no spray, one spray and two sprays). All traits measured were significantly affected by the agricultural production system (CONV or ORG) and N rate, although trends in their interactions were inconsistent between years. In Y2, yield was greatest in treatments with high N rates and in the ORG system. Biofertilizer treatments had a negative to neutral effect on grain yield. Baking quality traits such as protein content, lactic acid solvent retention capacity and sedimentation value (SV) were consistently greater in the CONV system and increased with the higher N application rates. Similarly, biofertilizer application had no effect on predictive baking quality traits, except for SV in year 1 of the study, where it increased with two sprays. Loaf volume was consistently greater from wheat grown in CONV treatments. From these results, we conclude that further research is warranted to evaluate the potential for biofertilizers to enhance N uptake and affect bread baking quality or other end-use traits. Additional research may be especially useful in organic production systems where biologically based N fertilizers are utilized, and treatments were not negatively affected by biofertilizer applications. Such strategies may be needed to increase protein quantity and gluten quality to optimize winter wheat production for bread baking qualities in the southeastern USA.

Registration of ‘KS Hamilton’ hard red winter wheat

AbstractHard 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 F6‐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.

Phosphorus Supply Does Not Affect Fusarium Crown Rot of Winter Wheat

Fusarium crown rot (FCR) is a major limitation to the wheat (Triticum aestivum L.) industry in the inland Pacific Northwest, United States. Genetic resistance to FCR is poorly understood and major gene resistance is not available in adapted cultivars. Chemical control is ineffective and crop rotations, which disrupt cycles of the disease, are not feasible in the region’s precipitation-limited climate. Cultural control methods are the only realistic option for farmers who struggle to minimize the impact of this disease. It is well established that FCR is favored by moisture-limited environments and an oversupply of plant-available nitrogen in soil. Effects of the supply of phosphorus in soil have not been clearly delineated. We conducted a 2-year FCR experiment at two locations in the low-precipitation zone (<30 cm) of north-central Oregon. Phosphorus fertilizer was applied in-furrow with phosphorus (P) at rates of 0, 5, and 15 kg ha−1, to plots planted with either a hard red or soft white winter wheat cultivar. The P at 15 kg ha−1 application rate increased tissue phosphorus concentration, early-season dry matter, and phosphorus uptake at both locations and both years of this study. Phosphorus treatment had no effect on grain yield, protein, or test weight. Phosphorus had no effect on the severity of FCR. This research improved our knowledge of cultural management boundaries as they relate to the control of FCR. [Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Effects of cultivars and nitrogen management on wheat grain yield and protein

AbstractLow grain protein in hard red winter (HRW) wheat (Triticum aestivum L.) is a serious challenge for rainfed wheat growers, particularly in years with elevated grain yield. Proper nitrogen (N) management with adequate N rate and application timing is critical for optimizing grain yield and protein content. This 2‐yr experiment evaluated the effects of different N rates and application timings (fall, spring, and split) on grain yield and protein of two HRW wheat cultivars. Field studies were conducted at four different sites across Nebraska under rainfed conditions in 2018/2019 (Year 1) and 2019/2020 (Year 2). A split‐plot randomized complete block design with wheat cultivars as the whole plots and factorial combinations of six N rates and three application timings as the subplots was used in four replications. Grain yield was associated positively and grain protein negatively with the water supply to demand ratio (WS/WD) in the season. Freeman cultivar yielded better in a year with higher WS/WD and a newly developed cultivar, Ruth, yielded better in a lower WS/WD year. Nitrogen fertilization significantly increased grain yield in the site‐years with moderately higher WS/WD. There was an increase in grain protein with increasing N rates at all site‐years. Spring and split‐applied N resulted in better grain yield than fall application in the site‐year when there was a risk of N loss. This experiment suggested that an effective N management strategy for winter wheat should account for and be adaptable to weather variability to optimize grain yield and protein content.

The Haplotype-Based Analysis of Aegilops tauschii Introgression Into Hard Red Winter Wheat and Its Impact on Productivity Traits.

The introgression from wild relatives have a great potential to broaden the availability of beneficial allelic diversity for crop improvement in breeding programs. Here, we assessed the impact of the introgression from 21 diverse accessions of Aegilops tauschii, the diploid ancestor of the wheat D genome, into 6 hard red winter wheat cultivars on yield and yield component traits. We used 5.2 million imputed D genome SNPs identified by the whole-genome sequencing of parental lines and the sequence-based genotyping of introgression population, including 351 BC1F3:5 lines. Phenotyping data collected from the irrigated and non-irrigated field trials revealed that up to 23% of the introgression lines (ILs) produce more grain than the parents and check cultivars. Based on 16 yield stability statistics, the yield of 12 ILs (3.4%) was stable across treatments, years, and locations; 5 of these lines were also high yielding lines, producing 9.8% more grain than the average yield of check cultivars. The most significant SNP- and haplotype-trait associations were identified on chromosome arms 2DS and 6DL for the spikelet number per spike (SNS), on chromosome arms 2DS, 3DS, 5DS, and 7DS for grain length (GL) and on chromosome arms 1DL, 2DS, 6DL, and 7DS for grain width (GW). The introgression of haplotypes from A. tauschii parents was associated with an increase in SNS, which was positively correlated with a heading date (HD), whereas the haplotypes from hexaploid wheat parents were associated with an increase in GW. We show that the haplotypes on 2DS associated with an increase in the spikelet number and HD are linked with multiple introgressed alleles of Ppd-D1 identified by the whole-genome sequencing of A. tauschii parents. Meanwhile, some introgressed haplotypes exhibited significant pleiotropic effects with the direction of effects on the yield component traits being largely consistent with the previously reported trade-offs, there were haplotype combinations associated with the positive trends in yield. The characterized repertoire of the introgressed haplotypes derived from A. tauschii accessions with the combined positive effects on yield and yield component traits in elite germplasm provides a valuable source of alleles for improving the productivity of winter wheat by optimizing the contribution of component traits to yield.

Races, disease symptoms and genetic variability in Pyrenophora tritici-repentis isolates from Oklahoma that cause tan spot of winter wheat

In recent years, tan spot of wheat caused by the fungus Pyrenophora tritici-repentis has become more prevalent in Oklahoma. Experiments were conducted to investigate the race structure, disease symptoms and genetic variability in P. tritici-repentis isolates collected from winter wheat over three decades. Race determination was conducted for 16 isolates based on expression of necrosis and/or chlorosis produced on wheat differentials. Variability in disease symptoms expressed by 12 isolates was determined on 13 hard red winter wheat cultivars grown in Oklahoma. In addition, genetic variability among 17 isolates was determined using amplified fragment length polymorphism-polymerase chain reaction (AFLP-PCR). All isolates except one (El Reno) were classified as race 1. Isolates varied widely in producing necrosis and/or chlorosis symptoms on wheat cultivars, but necrosis with a chlorotic halo was predominant (56.4%). AFLP-PCR analysis using 13 primer pairs produced a total of 494 alleles of which 285 were polymorphic. The overall genetic diversity among the isolates was 25.2%. Genetic relationships based on cluster analysis and principal component analysis showed only minor differences between isolates, and isolates did not form tight clusters or groups. The isolates of P. tritici-repentis were predominantly race 1; however, they produced a range of tan spot symptoms on wheat cultivars. The lack of distinct genetic grouping by the AFLP marker study indicates that the isolates used in this study likely originated from a single lineage.

Registration of ‘Scorpio’ hard red winter wheat

AbstractRecent changes in the environment and crop management practices of the Pacific Northwest region of the United States have challenged the development of successful hard red winter (HRW) wheat (Triticum aestivum L.) cultivars for the >500‐mm annual precipitation zones of the eastern part of the state of Washington. The use of N fertilizer and an increase in no‐till production practices have led to decreases in soil pH that can be toxic to wheat, especially in soils derived from previously forested land. The objective of this research was to develop a HRW wheat cultivar that combined tolerance to low‐pH soils with other important traits such as high yield, high grain volume weight, high grain protein concentration, acceptable end‐use quality, winterhardiness, and stripe rust resistance. ‘Scorpio’ (Reg. no. CV‐1169, PI 693629) HRW wheat was developed and released in March 2019 by the Agricultural Research Center of Washington State University. Scorpio was tested under the experimental designations HRW11064‐1‐DH‐1‐4 and WA8268. Scorpio is a semi‐dwarf cultivar adapted to the high‐rainfall wheat production regions of Washington. Scorpio is tolerant to low‐pH soils, has high‐temperature adult‐plant resistance to stripe rust, and has a midseason heading date, high grain volume weight, high grain protein concentration, and high grain yield. Scorpio has end‐use quality properties comparable to those of ‘LCS Jet’, ‘Keldin’, and ‘Whetstone’, which are acceptable for both domestic and export markets.

Registration of ‘Flathead’ hard red winter wheat

Abstract‘Flathead’ (Reg. no. CV‐1164, PI 693237) hard red winter (HRW) wheat (Triticum aestivum L.) was developed and released by the Montana Agricultural Experiment Station in 2019. Flathead was derived from a composite of two very closely related single crosses of the predominant cultivar ‘Yellowstone’ to stripe rust resistant source PI 640431, a hard white spring wheat backcross derivative of WA007900 that carries stripe rust all‐stage resistance genes Yr5 and Yr15. Flathead was developed using a modified bulk breeding method and selected as an F5:6 head row after phenotypic selection for stripe rust resistance at Kalispell, MT. Flathead was tested under the experimental number MT1564 in Montana yield trials from 2015 to 2019. Flathead is a high‐yielding HRW wheat cultivar with early maturity, short stature, medium grain protein concentration, excellent milling and baking quality, and a high level of all‐stage resistance to predominant races of stripe rust. Flathead was released for its early maturity, improved stripe rust resistance, and improved grain yield relative to other Montana‐adapted early heading cultivars.

Effects of fungicide chemical class, fungicide application timing, and environment on Fusarium head blight in winter wheat

Fusarium head blight (FHB), caused mainly by Fusarium graminearum, can result in devastating economic losses in small grain cereal crops. Management of FHB is by a combination of strategies and tactics including cultivar resistance, fungicide application at anthesis, and cultural practices such as crop rotation, tillage, and irrigation management. This study evaluated, under field conditions, the effects of fungicide chemical class (triazole versus strobilurin), fungicide application timing, and environment on FHB and its associated mycotoxin deoxynivalenol (DON). A moderately resistant hard red winter wheat cultivar, Overland, consistently had lower levels of FHB index (= index), Fusarium-damaged kernels (FDK), and DON, and higher yield compared to the susceptible hard red winter wheat cultivar Overley. The most effective fungicide treatment in reducing FHB, FDK, DON, and yield loss was Prosaro® (prothioconazole + tebuconazole) applied at early anthesis (BBCH 61; hereafter referred to as anthesis). Application of Prosaro 6 days post anthesis (DPA) achieved a slightly lower but comparable efficacy to that achieved by the anthesis application. Application of Prosaro at 12 DPA was least effective. The strobilurin fungicide Headline® (pyraclostrobin) was less effective than Prosaro in controlling FHB, FDK, and DON. In both cultivars, index, FDK, and DON were higher and yield was lower under irrigated compared to rain-fed conditions. These differences were more pronounced in a wet compared to a relatively dry growing season. The results from this study indicate that effective management of FHB can be achieved by combining cultivar resistance with a triazole fungicide applied at anthesis, and the window of fungicide application can be extended by up to 6 days post anthesis.

Registration of ‘Bobcat’ hard red winter wheat

Abstract‘Bobcat’ (Reg. no. CV‐1161, PI 693235) hard red winter (HRW) wheat (Triticum aestivum L.) was developed and released by the Montana Agricultural Experiment Station in September 2019. Bobcat is of unknown pedigree, derived from a composite of two related single crosses made in 2007: MT0598/98X366‐E29‐1 and 01X258‐C1/MT0598. MT0598 is an unreleased, hollow‐stem experimental line, and 98X366‐E29‐1 and 01X258‐C1 are unreleased, Montana solid‐stem experimental lines. Bobcat was developed using a modified bulk breeding method and selected as an F5:6 head row. Bobcat was tested under the experimental number MTS1588 from 2015 to 2019 in Montana. Quality was evaluated in multilocation Montana trials since 2015. Bobcat is a solid‐stem, high‐yielding HRW wheat cultivar with medium to high test weight, medium maturity, reduced height (Rht‐B1b), medium to high grain protein, and acceptable milling and baking quality. Bobcat was released for its improved host plant resistance to wheat stem sawfly (Cephus cinctus Nort.) conditioned by stem solidness, along with short stature, and improved yield potential relative to ‘Warhorse’, the current predominant solid‐stem cultivar in Montana.

AAC Network hard red winter wheat

AAC Network is a semi-dwarf hard red winter wheat (Triticum aestivum L.) cultivar that is well adapted across western Canada and eligible for grades of Canada Western Red Winter (CWRW) wheat. It was developed using wheat × maize pollen doubled haploid methodology. AAC Network was evaluated in the Western Canadian Winter Wheat Cooperative registration trials relative to CDC Buteo, Emerson, Moats, and AAC Elevate for 4 yr (2016–2019). Based on 44 replicated trials, AAC Network produced grain yield similar to AAC Elevate, the highest yielding check, with a protein concentration 0.9 units higher. AAC Network had fair to good winter survival, relatively late maturity, short straw with excellent lodging resistance, and high test weight. AAC Network expressed resistance to stem and stripe rust, moderate resistance to leaf rust and common bunt, and intermediate resistance to Fusarium head blight. In addition to increased grain protein concentration, AAC Network showed improvements in gluten strength and flour water absorption, and it maintained the excellent milling yield and low flour ash attributes of the CWRW wheat class.

Solvent retention capacity and swelling index of glutenin in hard red wheat flour as possible indicators of rheological and baking quality characteristics

To overcome the cost and expense of milling and baking hundreds of samples in wheat breeding programs, cereal chemists have developed various rapid predictive tests for end-use quality assessment. In this study, five small-scale rapid tests, including Solvent Retention Capacity (SRC) and Swelling Index of Glutenin (SIG), were compared for viability and accuracy to determine end-use quality using small quantities of flour. The tests were applied on commercial hard red spring and hard red winter wheat cultivars from two of the three main production regions in South Africa. Rheological and bread-baking characteristics were related to results of the rapid tests. Highly significant cultivar differences were seen for all rheological and baking-related characteristics, and SRC and SIG parameters, with a strong genotype effect. The environment effect was also highly significant across regions, especially for flour protein content (FPC), which affected the rheological and baking-related characteristics differently across the regions. Correlations among SRC, SIG, rheological, and baking quality-related parameters were highly significant, but inconsistent for the two production regions. Only lactic acid SRC and SIG correlated consistently with the rheological and baking quality-related characteristics in both production regions.

Development and deployment of KASP markers for multiple alleles of Lr34 in wheat

Key messageHeterogeneous Lr34 genes for leaf rust in winter wheat cultivar ‘Duster’ and KASP markers for allelic variation in exon 11 and exon 22 of Lr34.Wheat, Triticum aestivum (2n = 6x = 42, AABBDD), is a hexaploid species, and each of three homoeologous genomes A, B, and D should have one copy for a gene in its ancestral form if the gene has no duplication. Previously reported leaf rust resistance gene Lr34 has one copy on the short arm of chromosome 7D in hexaploid wheat, and allelic variation in Lr34 is in intron 4, exon 11, exon 12, or exon 22. In this study, we discovered that Oklahoma hard red winter wheat cultivar ‘Duster’ (PI 644,016) has two copies of the Lr34 gene, the resistance allele Lr34a and the susceptibility allele Lr34b. Both Lr34a and Lr34b were mapped in the same linkage group on chromosome 7D in a doubled-haploid population generated from a cross between Duster and a winter wheat cultivar ‘Billings’ which carries the susceptibility allele Lr34c. A chromosomal fragment including Lr34 and at least two neighboring genes on its proximal side but excluding genes on its distal side was duplicated in Duster. The Duster Lr34ab allele was associated with tip necrosis and increased resistance against leaf rust at adult plants in the Duster × Billings DH population tested in the field, demonstrating the function of the Duster Lr34ab allele in wheat. We have developed KASP markers for allelic variation in exon 11 and exon 22 of Lr34 in wheat. These markers can be utilized to accelerate the selection of Lr34 in wheat.

Tri5 gene expression analysis during postharvest storage of wheat grain from field plots treated with a triazole and a strobilurin fungicide

Fusarium head blight (FHB) and the associated mycotoxin deoxynivalenol (DON) negatively impact the wheat industry worldwide. In North America, FHB is mainly caused by Fusarium graminearum sensu stricto. The purpose of this study was to evaluate, under storage conditions, the expression of the DON biosynthetic gene trichodiene synthase (Tri5) of F. graminearum in grain of hard red winter wheat cultivars ‘Overley’ (FHB-susceptible) and ‘Overland’ (moderately resistant to FHB) from field plots treated or untreated with the triazole fungicide Prosaro and the strobilurin fungicide Headline. Infected grain was stored and periodically sampled to determine gene expression by qRT-PCR analysis. The F. graminearum housekeeping gene GAPDH was consistently detected, indicative of metabolically active fungi, and Tri5 detection was significantly higher in ‘Overley’ compared with ‘Overland’. Tri5 gene expression and DON concentrations showed little to no correlation; consequently, Tri5 expression levels did not accurately predict DON concentrations. The strobilurin did not significantly reduce Tri5 gene expression compared with untreated wheat. In the triazole treatment, a significant reduction in the relative expression of Tri5 was detected after 120 days, as well as a downregulation of Tri5 from 60 to 120 days of storage in ‘Overley’. In grain from strobilurin-treated plots of both cultivars, the expression of Tri5 increased from 0 to 30 days after tempering. Genetic expression of Tri5 that is necessary for the production of DON can increase during storage of high-moisture grain. Fusarium fungi can persist in wheat kernels for several months postharvest and may actively produce toxin during this period.

RNAi‐Mediated Silencing of Endogenous Wheat Genes EIF(Iso)4E‐2 and EIF4G Induce Resistance to Multiple RNA Viruses in Transgenic Wheat

ABSTRACTWheat (Triticum aestivum L.) lacks sources of effective resistance to the potyviruses Wheat streak mosaic virus (WSMV) and Triticum mosaic virus (TriMV). Potyviruses use host eukaryotic initiation factors (eIFs) to facilitate initial translation of their genomes, and many plant virus resistance genes are due to mutations in eIFs. Therefore, we hypothesized that silencing TaeIF(iso)4E and TaeIF4G would provide effective and broad‐spectrum virus resistance. Three transgenic wheat lines with an RNA interference (RNAi) hairpin construct targeting TaeIF(iso)4E and four lines with a hairpin construct targeting TaeIF4G were recovered through wheat transformation. Early generation lines were found to be resistant to WSMV and TriMV, and co‐inoculation of both. The lines were selfed to the T5 generation to insure transgene stability, as well as crossed onto the hard red winter wheat cultivar ‘Karl 92’ to test the RNAi constructs in a more adapted genetic background. Phenotypically, transgenic lines were found to be resistant to WSMV, TriMV, and mixed infections of both, were resistant to Soil‐borne wheat mosaic virus, and demonstrated a significant reduction in Barley yellow dwarf virus infection. The RNAi effectiveness on viral RNA was evaluated using reverse transcription quantitative polymerase chain reaction (PCR). An 18‐fold reduction in WSMV and TriMV viral RNA was found in the T5 transgenic lines when compared with control plants. Viral RNA reduction was also found in the F1, and BC1F1 crosses to Karl 92. These results demonstrate that a single, endogenously derived transgene in wheat can provide resistance to multiple viruses and provides a proof of concept for future gene editing.