White Wheat Cultivars Research Articles

Registration of ‘Runde’ spring bread wheat cultivar

Abstract‘Runde’ (Reg. no. CV‐1201, PI 702366; S02147‐7H‐0N‐2H‐0N) soft white spring bread wheat (Triticum aestivum L.) cultivar was developed by Crop Breeding Institute and released in December 2016 through the National Variety Release Committee. Runde was selected from a cross between S98066‐7H‐0G‐1H‐0N and F99012 made in 2002 at Harare Research Station. S98066‐7H‐0G‐1H‐0N is an experimental line made from a cross between F97009 (International Maize and Wheat Improvement Center [CIMMYT] line) and SC91155‐4H‐0G‐0H‐0G‐6G‐0N (Crop Breeding Institute line). F99012 is an experimental line developed by CIMMYT. Runde (S02147‐7H‐0N‐2H‐0N) is a product of a 2002 cross made in Zimbabwe as cross no. 147, using the pedigree method. Runde is an early maturing, rust tolerant, and high yielding cultivar. It is generally large‐seeded (49 g/1000 grains). The genotype was among the best performing cultivars with tolerance to rusts due to the presence of leaf rust and stem rust resistance genes, Lr34, Sr2, and Lr68. It has high flour extraction potential, good dough mixing characteristics, and high flour concentration.

QTL mapping of pre-harvest sprouting resistance in a white wheat cultivar Danby.

One major and three minor QTLs for resistance to pre-harvest sprouting (PHS) were identified from a white wheat variety "Danby." The major QTL on chromosome 3A is TaPHS1, and the sequence variation in its promoter region was responsible for the PHS resistance. Additive × additive effects were detected between two minor QTLs on chromosomes 3B and 5A, which can greatly enhance the PHS resistance. Pre-harvest sprouting (PHS) causes significant losses in yield and quality in wheat. White wheat is usually more susceptible to PHS than red wheat. Therefore, the use of none grain color-related PHS resistance quantitative trait loci (QTLs) is essential for the improvement in PHS resistance in white wheat. To identify PHS resistance QTLs in the white wheat cultivar "Danby" and determine their effects, a doubled haploid population derived from a cross of Danby × "Tiger" was genotyped using genotyping-by-sequencing markers and phenotyped for PHS resistance in two greenhouse and one field experiments. One major QTL corresponding to a previously cloned gene, TaPHS1, was consistently detected on the chromosome arm 3AS in all three experiments and explained 21.6-41.0% of the phenotypic variations. A SNP (SNP-222) in the promoter of TaPHS1 co-segregated with PHS in this mapping population and was also significantly associated with PHS in an association panel. Gene sequence comparison and gene expression analysis further confirmed that SNP-222 is most likely the causal mutation in TaPHS1 for PHS resistance in Danby in this study. In addition, two stable minor QTLs on chromosome arms 3BS and 5AL were detected in two experiments with allele effects consistently contributed by Danby, while one minor QTL on 2AS was detected in two environments with contradicted allelic effects. The two stable minor QTLs showed significant additive × additive effects. The results demonstrated that pyramiding those three QTLs using breeder-friendly KASP markers developed in this study could greatly improve PHS resistance in white wheat.

Anthocyanin bio-fortified colored wheat: Nutritional and functional characterization

Colored wheat, rich in anthocyanins, has created interest among the breeders and baking industry. This study was aimed at understanding the nutritional and product making potential of our advanced, high yielding and regionally adapted colored wheat lines. Our results indicated that our advanced colored wheat lines exhibited higher anthocyanin content and antioxidant activity than donor wheat lines and it varied in the order of white<purple<blue<black wheat. UPLC chromatogram revealed that anthocyanin composition and peak pattern is not only dependent on donor genotype but also background of recipient genotype. Interestingly, the purple wheat extract showed highest anti-inflammatory effect and followed the trend of white<blue<black<purple. Nutritional (carbohydrates, sugar, protein, ash, dietary fibre and vitamins) and processing parameters in relation to end-use quality (SDS sedimentation, gluten content, alveograph) of advanced colored lines were similar to high yielding white wheat cultivar. Colored wheat lines showed high iron and zinc content compared to white wheat indicating double bio-fortification. Therefore, our advanced colored wheat lines with high anthocyanin, iron and zinc contents showed antioxidant and anti-inflammatory activity and possessed desirable features for product making and commercial utilization.

TaMYB3, Encoding a Functional MYB Transcriptor, Isolated from the Purple Pericarp of Triticum aestivum

Purple pericarp is an interesting and useful trait in Triticum aestivum, but the molecular mechanism behind this phenotype remains unclear. The allelic variation in the MYB transcriptors is associated with the phenotype of pigmented organs in many plants. In this study, a MYB transcription factor gene, TaMYB3, was isolated using homology-based cloning and a differentially expressed gene mining approach, to verify the function of the MYB transcriptor in the purple pericarp. The coding sequence of TaMYB3 in cultivar Gy115 was the same as that in cultivar Opata. TaMYB3 was localized to FL0.62–0.95 on chromosome 4BL. The TaMYB3 protein contains DNA-binding and transcription-activation domains, and clustered on a phylogenetic tree with the MYB proteins that regulates anthocyanin and proanthocyanin biosynthesis. TaMYB3 localized in the nuclei of Arabidopsis thaliana and wheat protoplasts after it was transiently expressed with PEG transformation. TaMYB3 induced anthocyanin synthesis in the pericarp cells of Opata in the dark in collaboration with the basic helix–loop–helix protein ZmR, which is also the function of ZmC1. However, TaMYB3 alone did not induce anthocyanin biosynthesis in the pericarp cells of the white grain wheat cultivar Opata in the light after bombardment, whereas the single protein ZmR did. Light increased the expression of TaMYB3 in the pericarp of Gy115 and Opata, but only induced anthocyanin biosynthesis in the grains of Gy115. Our results extend our understanding of the molecular mechanism of the purple pericarp trait in T. aestivum.

Genomic Regions Associated with Tolerance to Freezing Stress and Snow Mold in Winter Wheat.

Plants grown through the winter are subject to selective pressures that vary with each year’s unique conditions, necessitating tolerance of numerous abiotic and biotic stress factors. The objective of this study was to identify molecular markers in winter wheat (Triticum aestivum L.) associated with tolerance of two of these stresses, freezing temperatures and snow mold—a fungal disease complex active under snow cover. A population of 155 F2:5 recombinant inbred lines from a cross between soft white wheat cultivars “Finch” and “Eltan” was evaluated for snow mold tolerance in the field, and for freezing tolerance under controlled conditions. A total of 663 molecular markers was used to construct a genetic linkage map and identify marker-trait associations. One quantitative trait locus (QTL) associated with both freezing and snow mold tolerance was identified on chromosome 5A. A second, distinct, QTL associated with freezing tolerance also was found on 5A, and a third on 4B. A second QTL associated with snow mold tolerance was identified on chromosome 6B. The QTL on 5A associated with both traits was closely linked with the Fr-A2 (Frost-Resistance A2) locus; its significant association with both traits may have resulted from pleiotropic effects, or from greater low temperature tolerance enabling the plants to better defend against snow mold pathogens. The QTL on 4B associated with freezing tolerance, and the QTL on 6B associated with snow mold tolerance have not been reported previously, and may be useful in the identification of sources of tolerance for these traits.

OAC Emmy, soft white winter wheat

Tamburic-Ilincic, L. and Smid, A. 2013. OAC Emmy, soft white winter wheat. Can. J. Plant Sci. 93: 965-967. OAC Emmy is a soft white winter wheat (Triticum aestivum L.) cultivar registered for Ontario, Canada. It has high grain yield, with good pastry and biscuit quality and similar resistance to Fusarium head blight (FHB) as the moderately susceptible check Emmit. OAC Emmy is well adapted for the winter wheat growing areas of South Western Ontario.

Registration of ‘Cara’ Soft White Winter Club Wheat

Club wheat (Triticum aestivum ssp. compactum) is an important component of the export grain market for the Pacific Northwest. Our objective was to develop a club wheat cultivar with resistance to stripe rust (caused by Puccinia striiformis f. sp. tritici Westend.) and strawbreaker foot rot [caused by Oculimacula yallundae Crous &amp; W. Gams (Wallwork &amp; Spooner) and O. acuformis (Boerema, R. Pieters &amp; Hamers) Crous. &amp; W. Gams] and with the end‐use qualities that make club wheat a specialty product. The bulk pedigree breeding method was used to select ‘Cara’ (Reg. No. CV‐1078, PI 643435) from the cross WA7752//WA6581/WA7217 made in 1992. Cara is a semidwarf wheat with the Rht‐D1b dwarfing allele. Cara has winter hardiness equal to that of other club wheat cultivars—Bruehl, Chukar, and Coda—but less than the soft white wheat cultivars Eltan (PI 536994) or Masami (PI 634715). Cara was evaluated in multi‐environment replicated plot trials in the Washington since 2003. Grain yields were equal to or better than other club and soft white cultivars in the 30‐ to 40‐cm and the 40‐ to 50‐cm annual precipitation zones. The milling and baking quality of Cara was equal to those of the best club wheat check cultivars. Cara is resistant to all races of stripe rust prevalent since 2001, possessing Yr17 and unknown genes for stripe rust resistance. It is also resistant to strawbreaker foot rot, possessing Pch1. Cara provides growers with an agronomically competitive cultivar with resistance to stripe rust and strawbreaker foot rot plus excellent club wheat end‐use quality.

Color of Whole‐Wheat Foods Prepared from a Bright‐White Hard Winter Wheat and the Phenolic Acids in Its Coarse Bran

The color of wheat kernels often impacts the color and thereby the value of wheat-based foods. A line of hard white winter wheat (B-W HW) with bright appearing kernels has been developed at the Kansas State Agricultural Research Center. The objective of this study was to compare the color of several foods made from the B-W HW wheat with those of 2 hard white wheat cultivars, Trego and Lakin. The B-W HW kernels showed higher lightness (L*, 57.6) than Trego (55.5) and Lakin (56.8), and the increased lightness was carried over to its bran and whole-wheat flour. Alkaline noodle and bread crumb made from the B-W HW whole-wheat flour showed slightly higher lightness (L*) than those made from Trego and Lakin. The sum of soluble and bound phenolics extracted from the 3 wheat brans, which had not been preextracted to remove lipids, was found to be 17.22 to 18.98 mg/g. The soluble phenolic acids in the brans were principally vanillic, ferulic, and syringic. The bound phenolic acids in the brans were dominated by ferulic, which accounted for 50.1% to 82.2% of total identified bound phenolic acids. Other bound phenolic acids were protocatechuic, caffeic, syringic, trans-cinnamic, p-hydroxybenzoic, p-coumaric, and vanillic. The lightness (L*) values of coarse wheat brans correlated positively with their levels of bound protocatechuic (r = 0.72, P < 0.01) and p-hydroxybenzoic acids (r = 0.75, P < 0.01).

Genetic analysis of preharvest sprouting tolerance in bread wheat (Triticum aestivum L. emend. Thell.)

Rains during grain ripening in wheat (Triticum aestivum L.) can cause preharvest sprouting (PHS), which drastically affects the grain yield and the baking quality of flour. In the present study, to screen 7 cultivars and 4 lines of spring bread wheat for PHS, germination tests were conducted with seeds obtained from wet spikes harvested immediately after natural rainfall. Germination tests were carried out as 3 different treatments: 1) seeds immediately germinated after hand-threshing on sampling day (T_1), 2) seeds germinated 1 week later after hand-threshing (T_2), and 3) 10 intact spikes kept on paper under laboratory conditions at room temperature, hand threshed and then put to germinate 7 days later (T_3). Red-grained cultivars Sagitario and Pandas, red-grained line F6 0314.76/Mrl, and white-grained cultivar Sunlin showed the higher PHS tolerance, while other wheat cultivars and lines were found to be susceptible to PHS under all treatment conditions. To evaluate the mode of inheritance and combining ability of PHS tolerance, a diallel cross was made between 3 white-grained (susceptible) and 2 red-grained wheat (resistant) cultivars. Analysis of variance for combining ability showed the predominance of an additive gene effect for PHS tolerance, as the variance of the general combining ability was higher than the specific combining ability for both percent germination and germination index. Pandas and Sagitario showed positive contributions toward increasing PHS tolerance in the F_1 progenies. Results presented in this study will provide useful information for wheat breeders about PHS tolerance or dormancy level in commonly grown wheat cultivars in the Mediterranean region of Turkey, and help them in the development of white wheat cultivars with an inherently higher sprouting tolerance.

Dissection of genetic components of preharvest sprouting resistance in white wheat

Preharvest sprouting (PHS) in rain-affected wheat (Triticum aestivum) is a major constraint to the production of high-quality wheat, especially in regions where white grain wheat cultivars are preferred. To characterize quantitative trait loci (QTLs) for PHS resistance and seed dormancy (SD), we evaluated 162 recombinant inbred lines developed from the cross between PHS-resistant white wheat landrace Tutoumai A and PHS-susceptible white wheat cultivar ‘Siyang 936’ for PHS resistance and SD in field and greenhouse experiments. Composite interval mapping (CIM) identified four QTLs for PHS resistance and long SD that explained up to 45 and 40.8% of the phenotypic variation in five PHS and four SD experiments, respectively. Qphs.pseru-4A.1 was detected in three of the five PHS experiments, and Qphs.pseru-5B.1, Qphs.pseru-5B.2, and Qphs.pseru-4B.1 were detected in two of the five PHS experiments, respectively. All four QTLs for PHS resistance also affected SD. Qphs.pseru-4A.1 was significant in all four SD experiments; the other three QTLs were detected only in one experiment. Additive and epistatic effects were observed for PHS resistance and SD. Besides three additive QTLs for PHS resistance and two for long SD, an additional 11 and 10 QTLs were detected with epistatic effects on PHS resistance and SD, respectively. The major genetic component of PHS resistance was SD, and other genetic factors may also contribute to PHS resistance in this population.

Forage Yield and Nutritive Value of Hard Red and Hard White Winter Wheat

Six hard red (‘2137’, ‘Jagalene’, ‘Jagger’, ‘OK101’, ‘Stanton’, and ‘Thunderbolt’) and six hard white (‘Burchett’, ‘Lakin’, ‘NuFrontier’, ‘NuHills’, ‘NuHorizon’, and ‘Trego’) winter wheat (Triticum aestivum L.) cultivars were evaluated for forage yield and nutritive value. Forage samples were collected in December, March, and May. Red cultivars averaged greater total season forage yield in one growing season, but yield differences among cultivars within a color group were greater than differences between color groups, indicating that color did not affect yield as much as cultivar. Total growing season forage yield was greatest among red cultivars 2137, Jagalene, Stanton, and Thunderbolt and white cultivar Trego. Color had no effect on forage nutritive value. Crude protein averaged 230 g kg−1 in December, 240 g kg−1 in March, and 140 g kg−1 in May. Acid detergent fiber averaged 190 g kg−1 in December, 240 g kg−1 in March, and 320 g kg−1 in May. Neutral detergent fiber averaged 430 g kg−1 in December, 410 g kg−1 in March, and 550 g kg−1 in May. Total digestible nutrients averaged 790 g kg−1 in December, 740 g kg−1 in March, and 670 g kg−1 in May. Nitrate‐nitrogen averaged 247 mg kg−1 in December, 550 mg kg−1 in March, and 1366 mg kg−1 in May. Both red and white wheat cultivars can be used in a dual‐purpose system with no adverse affects on forage yield or nutritive value. Producers should select cultivars adapted to their grazing system and environment.

Microsatellite Markers for Kernel Color Genes in Wheat

The establishment of hard white wheat (Triticum aestivum L.) as a viable alternative for growers has been impeded by several factors, one of which is that new hard white wheat cultivars may not be competitive with hard red cultivars. This is due to the fact that most breeding programs devote more resources to hard red wheat, and that the genetics of kernel color makes rapid conversion of red to white kernel color problematic. Three homoeologous loci control kernel color, with red being dominant. A single red allele is sufficient to cause the kernel to be classified as red. A rapid conversion of red‐seeded genotypes to white‐seeded types would be facilitated by the use of molecular markers to help select for the recessive alleles for white color. In this experiment, we developed three populations that were segregating at only one of each of three respective color loci, being homozygous recessive at the other two. F2 plants or recombinant inbred lines were assayed for kernel color and screened with a series of microsatellite markers. Linked microsatellite markers were identified for all loci. A validation experiment was established with a population of 1786 F2 plants from a cross between a red‐seeded line and white‐seeded line. The markers were 100% diagnostic for the white‐seeded phenotype in this population. Thus, the markers will find utility in backcrossing programs to convert red‐seeded wheat to white.

Quantitative trait loci for resistance to pre-harvest sprouting in US hard white winter wheat Rio Blanco

Pre-harvest sprouting (PHS) of wheat is a major problem that severely limits the end-use quality of flour in many wheat-growing areas worldwide. To identify quantitative trait loci (QTLs) for PHS resistance, a population of 171 recombinant inbred lines (RILs) was developed from the cross between PHS-resistant white wheat cultivar Rio Blanco and PHS-susceptible white wheat breeding line NW97S186. The population was evaluated for PHS in three greenhouse experiments and one field experiment. After 1,430 pairs of simple sequence repeat (SSR) primers were screened between the two parents and two bulks, 112 polymorphic markers between two bulks were used to screen the RILs. One major QTL, QPhs.pseru-3AS, was identified in the distal region of chromosome 3AS and explained up to 41.0% of the total phenotypic variation in three greenhouse experiments. One minor QTL, QPhs.pseru-2B.1, was detected in the 2005 and 2006 experiments and for the means over the greenhouse experiments, and explained 5.0-6.4% of phenotypic variation. Another minor QTL, QPhs.pseru-2B.2, was detected in only one greenhouse experiment and explained 4.5% of phenotypic variation for PHS resistance. In another RIL population developed from the cross of Rio Blanco/NW97S078, QPhs.pseru-3AS was significant for all three greenhouse experiments and the means over all greenhouse experiments and explained up to 58.0% of phenotypic variation. Because Rio Blanco is a popular parent used in many hard winter wheat breeding programs, SSR markers linked to the QTLs have potential for use in high-throughput marker-assisted selection of wheat cultivars with improved PHS resistance as well as fine mapping and map-based cloning of the major QTL QPhs.pseru-3AS.

Relationship between yield and mineral nutrient concentrations in historical and modern spring wheat cultivars

The diet of approximately three billion people worldwide is nutrient deficient and most of the world’s poorest people are dependent on staple food crops as their primary source of micronutrients. One component of the solution to nutrient deficiencies is collaboration among plant breeders, cereal chemists and nutritionists to produce staple crop cultivars with increased mineral nutrient concentration. Sixty-three historical and modern wheat cultivars were evaluated for grain yield and concentration of calcium, copper, iron, magnesium, manganese, phosphorus, selenium, and zinc. While grain yield has increased over time, the concentrations of all minerals except calcium have decreased. Thus a greater consumption of whole wheat bread from modern cultivars is required to achieve the same percentage of recommended dietary allowance levels contributed by most of the older cultivars. The decrease in mineral concentration over the past 120 years occurs primarily in the soft white wheat market class, whereas in the hard red market class it has remained largely constant over time. This suggests that plant breeders, through intentional selection of low ash content in soft white wheat cultivars, have contributed to the decreased mineral nutrient concentration in modern wheat cultivars. These results contradict the theory that there exists a genetically based, biological trade-off between yield and mineral concentrations. Therefore, using the abundant variation present in wheat cultivars, it should be possible to improve mineral concentrations in modern cultivars without negatively affecting yield.

Registration of ‘UI Darwin’ Wheat

‘UI Darwin’ (Reg. No. CV‐1022, PI 639953) is a hard white winter wheat (Triticum aestivum L.) developed by the Idaho Agricultural Experiment Station and released in February 2006. UI Darwin (pedigree IDO445/‘Manning’) was tested under the experimental numbers A93151W‐85 and IDO604. It is a tall semidwarf wheat released for crop‐fallow rotations of the Intermountain West, where few hard white wheat cultivars are available. UI Darwin has improved resistance to stripe rust (Puccinia striiformis Westend.) relative to ‘Bonneville’ hard red winter wheat with resistance to dwarf bunt (Tilletia controversa Kühn in Rabenh) at similar levels to Bonneville. In 16 rainfed yield trials grown in Idaho from 2001 to 2005, UI Darwin had an average grain yield of 3200 kg ha‐1, similar to Bonneville (3050 kg ha‐1) and ‘Weston’ (3190 kg ha‐1) but less than ‘Gary’ (3560 kg ha‐1. UI Darwin has improved bread baking quality compared with current hard white winter wheat cultivars and has excellent color in akaline noodle products. UI Darwin had an average pup‐loaf volume of 1075 mL, similar to hard red winter wheat cultivars Bonneville (1044 mL) and Weston (1064 mL) but greater than the hard white wheat cultivar Gary (963 mL).

A major QTL controlling seed dormancy and pre-harvest sprouting resistance on chromosome 4A in a Chinese wheat landrace

Wheat pre-harvest sprouting (PHS) can cause significant reduction in yield and end-use quality of wheat grains in many wheat-growing areas worldwide. To identify a quantitative trait locus (QTL) for PHS resistance in wheat, seed dormancy and sprouting of matured spikes were investigated in a population of 162 recombinant inbred lines (RILs) derived from a cross between the white PHS-resistant Chinese landrace Totoumai A and the white PHS-susceptible cultivar Siyang 936. Following screening of 1,125 SSR primers, 236 were found to be polymorphic between parents, and were used to screen the mapping population. Both seed dormancy and PHS of matured spikes were evaluated by the percentage of germinated kernels under controlled moist conditions. Twelve SSR markers associated with both PHS and seed dormancy were located on the long arm of chromosome 4A. One QTL for both seed dormancy and PHS resistance was detected on chromosome 4AL. Two SSR markers, Xbarc 170 and Xgwm 397, are 9.14 cM apart, and flanked the QTL that explained 28.3% of the phenotypic variation for seed dormancy and 30.6% for PHS resistance. This QTL most likely contributed to both long seed dormancy period and enhanced PHS resistance. Therefore, this QTL is most likely responsible for both seed dormancy and PHS resistance. The SSR markers linked to the QTL can be used for marker-assisted selection of PHS-resistant white wheat cultivars.

Reaction of Elite Wheat Genotypes from the Northern Great Plains of North America to Septoria Diseases.

Stagonospora nodorum blotch (SNB), caused by Phaeosphaeria nodorum, and Septoria tritici blotch (STB), caused by Mycosphaerella graminicola, are the main pathogens of the Septoria disease complex of wheat (Triticum aestivum) in North America. This study was conducted to determine the disease reaction of 126 elite hard red spring, white, and durum wheat cultivars and advanced breeding lines collected from the northern Great Plains of the United States and Canada to SNB and STB. Seedlings of the 126 wheat genotypes were evaluated for resistance to SNB and STB under controlled environmental conditions. Moreover, these 126 wheat genotypes also were infiltrated with culture filtrate of P. nodorum isolate Sn2000. Based on disease reactions, three cultivars (McNeal, Dapps, and Oklee) and 12 advanced breeding lines (CA-901-580W, 97SO254-8-1, MN03291, MN03308, WA007925, MT0245, ND756, ND801, ND803, ND808, ND809, and ND811) adapted to the northern Great Plains were found to be resistant to both Septoria diseases and insensitive to the culture filtrate. Additionally, eight genetically diverse lines and cultivars, including two tetraploid wheat genotypes, were identified to be resistant to both Septoria diseases. These results suggest that the wheat genotypes contain a broad genetic base for resistance to the Septoria diseases in the northern Great Plains of the United States and Canada, and the resistant sources identified in this study may be utilized in wheat-breeding programs.

Influence of Cultivar and Environment on Water‐Soluble and Water‐Insoluble Arabinoxylans in Soft Wheat

ABSTRACTArabinoxylans are hydrophilic nonstarch polysaccharides found in wheat grain as minor constituents. Arabinoxylans can associate with large amounts of water through hydrogen bonding and can form oxidative gels. These properties are important factors in end‐use quality of wheat. The objective of this study was to delineate the influence of wheat cultivar and growing environment on variation in water‐soluble (WS‐AX), waterinsoluble (WI‐AX), and total (TO‐AX) arabinoxylan contents of flour and whole grain meal. This study included seven spring and 20 winter soft white wheat cultivars grown in 10 and 12 environments, respectively (each evenly split over two crop years). Univariate analysis of variance (ANOVA) and multivariate analysis of variance with canonical analysis (MANOVA) was used to evaluate sources of variation. Variation in arabinoxylan contents and absolute amounts (xylose equivalents) among the two cultivar sample sets (spring and winter) was similar, and both cultivar and environment were significant sources of variation. The cultivar‐by‐environment interaction was relatively unimportant. Results indicate that the variation in arabinoxylan content is primarily influenced by cultivar and secondarily influenced by environment. Within arabinoxylan fractions, WS‐AX content is primarily influenced by genotype, while WI‐AX content is more greatly influenced by the environment.

The influence of different nitrogen treatments on the size distribution of protein fractions in hard and soft wheat

The relative quantity of specific proteins, protein subunits, as well as amount and size-distribution of polymeric proteins in wheat kernels may vary due to environmental conditions. In this study, the effect of different nitrogen treatments on polymeric and monomeric proteins in wheat was determined. Two soft white biscuit wheat cultivars, a cracker wheat and a hard red bread wheat were planted under irrigation in a randomized complete block design with three replications in two successive years at six different nitrogen treatments. SE-HPLC was used to determine the amount of monomeric and polymeric proteins, and various quality characteristics were measured after harvesting. The large and small SDS-extractable polymeric proteins were not influenced by different N levels. There was a strong cultivar influence, where some cultivars had a larger reaction to N treatments than others. The later application (at flag leaf stage) of nitrogen did not increase the protein fractions. The total amount of N given seemed to have a greater influence on the protein fractions than the timing of the fertilizer application. The lowest N treatment consistently gave the lowest flour protein content value. There was a strong correlation between flour protein content and large monomeric proteins.

Pollen‐Mediated Gene Flow from Blue Aleurone Wheat to Other Wheat Cultivars

Cross‐pollination among wheat (Triticum aestivum L.) cultivars historically has not been a major concern for wheat producers. However, with the introduction of genetically engineered wheat, there may be a need to ensure genetic purity, which will require knowledge of the frequency and distance that pollen‐mediated gene flow can occur in wheat. This information will be necessary to develop (i) isolation distances that maintain predictable degrees of genetic purity in seed wheat production and (ii) practices to manage pollen‐mediated gene flow in commercial wheat production. Field experiments were conducted from 2000 to 2003 at five locations in Oregon, Idaho, and Washington to determine the potential for pollen‐mediated gene flow among winter wheat cultivars. Each experiment was designed as a Nelder wheel with 16 equally spaced rays extending away from a central pollen source of blue aleurone wheat. Each ray was 46 m long and contained two rows each of an early‐ and late‐flowering soft white wheat cultivar. Seed samples were collected at 1.8‐m intervals along each ray and examined for blue seed, which indicated successful hybridization with the pollen source. Although blue seed was found in some samples at all five locations, most samples (98%) contained no blue seed. Pollen‐mediated gene flow generally was in the direction of the prevailing wind and tended to occur more often at the sites with lower temperature and higher humidity during pollination. The maximum distance that gene flow was detected was 42 m from the pollen source and the maximum outcrossing in an individual sample was 0.45%. At four locations, no outcrossing was detected beyond 30 m from the pollen source; however, at one site, 13% of the blue seed was found between 30 and 42 m. Pollen‐mediated gene flow potential may differ for other wheat cultivars and environmental conditions. Depending on the required genetic purity standards for wheat seed, an isolation distance of 45 m or more may be required.