Research Notes : Influence of maturity date on the oil content of soybeans with genetically altered fatty acid composition

sed oleic acid percentage has been proven successful in decreasing the percentage of linolenic acid in soybean oil (Burton et al., 1983). In the first four cycles of selection, the percentage of oleic acid in the seed oil increased linearly at an average rate of 1.6 + 0.2% per cycle whereas linoleic and linolenic acid percentages showed linear decreases. Four additional cycles of selection for increased oleic acid and two cycles for decreased oleic acid levels are currently being evaluated in a wide range of environ-ments

Research Notes : Inheritance of fatty acid composition in soybean seed oil

While it has been demonstrated that the fatty acid composition of soybean oil can be changed by recurrent selection (Wilson et al., 1981), there is little information about the genetic control of oil biosynthesis in soybean seeds. In some species, such as rape (Downey and Harvey, 1963), safflower (Yermanos et al., 1967), and flax (Yermanos and Knowles, 1962), the male parent has a significant effect on the fatty acid composition of oil from F1 hybrid seeds. In corn (Jellum, 1966) and soybeans (Brim et al., 1968), the male parent has almost no effect on oil composition of F1 hybrid seeds

Pm223899, a new recessive powdery mildew resistance gene identified in Afghanistan landrace PI 223899

Key message A new recessive powdery mildew resistance gene, Pm223899, was identified in Afghanistan wheat landrace PI 223899 and mapped to an interval of about 831 Kb in the terminal region of the short arm of chromosome 1A. Abstract Wheat powdery mildew, a globally important disease caused by the biotrophic fungus Blumeria graminis f.sp. tritici (Bgt), has occurred with increased frequency and severity in recent years, and some widely deployed resistance genes have lost effectiveness. PI 223899 is an Afghanistan landrace exhibiting high resistance to Bgt isolates collected from the Great Plains. An F2 population and F2: 3 lines derived from a cross between PI 223899 and OK1059060-126135-3 were evaluated for response to Bgt isolate OKS(14)-B-3-1, and the bulked segregant analysis (BSA) approach was used to map the powdery mildew resistance gene. Genetic analysis indicated that a recessive gene, designated Pm223899, conferred powdery mildew resistance in PI 223899. Linkage analysis placed Pm223899 to an interval of about 831 Kb in the terminal region of chromosome 1AS, spanning 4,504,697–5,336,062 bp of the Chinese Spring reference sequence. Eight genes were predicted in this genomic region, including TraesCS1AG008300 encoding a putative disease resistance protein RGA4. Pm223899 was flanked proximally by a SSR marker STARS333 (1.4 cM) and distally by the Pm3 locus (0.3 cM). One F2 recombinant was identified between Pm3 and Pm223899 using a Pm3b-specific marker, indicating that Pm223899 is most likely a new gene, rather than an allele of the Pm3 locus. Pm223389 confers a high level of resistance to Bgt isolates collected from Pennsylvania, Oklahoma, Nebraska, and Montana. Therefore, Pm223389 can be used to enhance powdery mildew resistance in these states. Pm3b-1 and STARS333 have the potential to tag Pm223389 in wheat breeding

Nitrogen use and biomass distribution in culms of winter wheat populations selected from grain-only and dual-purpose systems

Beginning in late fall and ending at jointing in early spring, winter wheat (Triticum aestivum L.) crops in the southern Great Plains are often grazed by stocker cattle (Bos taurus L.) and then harvested for grain. Traditionally, dual-purpose (grazing plus grain) wheat cultivars are developed from a grain-only production system. Because culms of dual-purpose grown wheat may forfeit productivity gains for grain only developed cultivars, we evaluated N and biomass traits at anthesis and maturity for 12 sets of subpopulations (each set a unique genetic background) to test benefits of making selections from a dual-purpose system. Sets came from F2 sources and contained a "Base" F3 bulk population and F5 bulk populations mass selected from the F2 within grain-only and dual-purpose production systems. The 12 sets of subpopulations were evaluated in grain-only and dual-purpose production systems in 2001-2002 and 2002-2003. At anthesis, main effects (year, system, genetic background, subpopulation selection environment) were significant for culm dry weight and N, and flag leaf dry weight. Among selections, differences for these traits were small (2.0-3.5%) with no difference between grain-only and dual-purpose selections; differences among genetic backgrounds, however, were large (21-30%). At maturity, differences (7.6-20%) for grain dry weight and kernel mass, harvest index (HI), N content, grain N, and N harvest index (NHI) of individual culms occurred among genetic backgrounds. Differences among subpopulations were smaller (1.4-4.5%) and significant for only culm and grain dry weight, kernel number and mass, and culm N content. Selections made from the dual-purpose environment performed similar to those from the grain-only environment when grown in either production system.Peer reviewedPlant and Soil Science

Association analysis of stem rust resistance in U.S. winter wheat

Citation: Zhang D, Bowden RL, Yu J, Carver BF, Bai G (2014) Association Analysis of Stem Rust Resistance in U.S. Winter Wheat. PLoS ONE 9(7): e103747. https://doi.org/10.1371/journal.pone.0103747Stem rust has become a renewed threat to global wheat production after the emergence and spread of race TTKSK (also known as Ug99) and related races from Africa. To elucidate U.S. winter wheat resistance genes to stem rust, association mapping was conducted using a panel of 137 lines from cooperative U.S. winter wheat nurseries from 2008 and simple sequence repeat (SSR) and sequence tagged site (STS) markers across the wheat genome. Seedling infection types were evaluated in a greenhouse experiment using six U.S. stem rust races (QFCSC, QTHJC, RCRSC, RKQQC, TPMKC and TTTTF) and TTKSK, and adult plant responses to bulked U.S. races were evaluated in a field experiment. A linearization algorithm was used to convert the qualitative Stakman scale seedling infection types for quantitative analysis. Association mapping successfully detected six known stem rust seedling resistance genes in U.S. winter wheat lines with frequencies: Sr6 (12%), Sr24 (9%), Sr31 (15%), Sr36 (9%), Sr38 (19%), and Sr1RS[superscript Amigo] (8%). Adult plant resistance gene Sr2 was present in 4% of lines. SrTmp was postulated to be present in several hard winter wheat lines, but the frequency could not be accurately determined. Sr38 was the most prevalent Sr gene in both hard and soft winter wheat and was the most effective Sr gene in the adult plant field test. Resistance to TTKSK was associated with nine markers on chromosome 2B that were in linkage disequilibrium and all of the resistance was attributed to the Triticum timopheevii chromosome segment carrying Sr36. Potential novel rust resistance alleles were associated with markers Xwmc326-203 on 3BL, Xgwm160-195 and Xwmc313-225 on 4AL near Sr7, Xgwm495-182 on 4BL, Xwmc622-147 and Xgwm624-146 on 4DL, and Xgwm334-123 on 6AS near Sr8. Xwmc326-203 was associated with adult plant resistance to bulked U.S. races and Xgwm495-182 was associated with seedling resistance to TTKSK

2009 wheat variety comparison

The Oklahoma Cooperative Extension Service periodically issues revisions to its publications. The most current edition is made available. For access to an earlier edition, if available for this title, please contact the Oklahoma State University Library Archives by email at [email protected] or by phone at 405-744-6311

2012 wheat variety comparison

The Oklahoma Cooperative Extension Service periodically issues revisions to its publications. The most current edition is made available. For access to an earlier edition, if available for this title, please contact the Oklahoma State University Library Archives by email at [email protected] or by phone at 405-744-6311

Agronomic performace in acid soils of wheat lines selected for hematoxylin staining pattern

Laboratory screening techniques enable detection of varying degrees of A1 tolerance during seedling development, but their application to crop improvement programs must be verified in the field. The objective of this study was to compare agronomic responses of wheat (Triticum aestivum L. emend. Thell.) lines differing in hematoxylin- staining pattern under naturally acidic and limed field conditions. Experiments were conducted on Bethany-Kirkland (fine, mixed, thermic Pachic-Udertic Paleustolls) or Grant-Pond Creek (fine-silty, mixed thermic Udic-Pachic Argiustolls) silt loam soil complexes. Four sets of three experimental lines were classified as very susceptible (VS), moderately susceptible (MS), intermediate (I), or tolerant based on hematoxylin staining pattern, and evaluated in limed and unlimed plots as separate experiments in 1988 and 1989. The VS group produced the fewest spikes per square meter and the lowest above-ground biomass and grain yield in the unlimed treatments; no such reductions occurred in the limed treatments. Differences in agronomic performance were found between groups of VS and MS lines, with relatively little differentiation among MS, I, and T groups. Comparison of two sister lines from the VS and T groups revealed a 12% increase in spike density, 11% increase in biomass, and a 14% increase in grain yield of the tolerant sib under acidic conditions. The two sibs performed similarly under limed conditions, except the VS line was superior in grain yield. The hematoxylin staining procedure shows promise for identifying wheat genotypes with potentially high sensitivity to acidic soils in the southern Great Plains.Peer reviewedAgronom

Covariation for microsatellite marker alleles associated with Rht8 and coleoptile length in winter wheat

Wheat (Triticum aestivum L.) cultivars with greater coleoptile elongation are preferred in low-precipitation dryland regions and in early-planted management systems of the Great Plains, but the presence of GA3 (gibberellin)-insensitive dwarfing genes tends to restrict coleoptile elongation. The agronomic value of Rht8 and the discovery of its diagnostic microsatellite marker, Xgwm 261, have accelerated breeders' interest in Rht8 as an alternative dwarfing gene. Our objectives were to determine allelic distributions at the marker locus in contemporary samples of hard winter and soft red winter wheat relative to samples of Chinese accessions from a Rht8-rich geographic region, and to compare coleoptile elongation in the presence or absence of Rht8 determined by the Xgwm 261 marker. The 165-bp (primarily hard winter wheats) and the 174-bp (primarily soft red winter wheats) alleles of Xgwm 261 were most frequent. About 8% of all U.S. accessions carried the 192-bp allele diagnostic for Rht8, compared with 64% of the Chinese accessions. Coleoptile length varied among accessions from 4.4 to 11.4 cm. Frequency distributions for 192- and non-192-bp genotypes showed no advantage of the 192-bp allele to coleoptile elongation. None of the 192-bp genotypes from the Great Plains showed greater coleoptile length than 'TAM 107', a hard red winter cultivar without Rht8 often chosen over contemporary cultivars for its greater emergence capacity with deeper seed placement. Since coleoptile elongation may be controlled by several quantitative trait loci, identifying only the presence of 192-bp allele of Xgwm 261 may be misleading if the primary motivation for its deployment is to increase coleoptile length in a semidwarf plant type.Peer reviewedPlant and Soil Science

Genetic trends in winter wheat yield and test weight under dual-purpose and grain-only management systems

Wheat (Triticum aestivum L.) cultivars of the southern Great Plains are traditionally bred in environments managed for grain production only but are commonly grown for the dual-purpose of producing winter forage and grain from the same crop. To what extent grain yield and test weight are consistently expressed in those environments requires investigation relative to long-term attempts to improve them genetically. A historical set of hard red winter (HRW) wheat cultivars was evaluated under grain-only and dual-purpose management systems to compare their agronomic performance and derived estimates of genetic progress. Separate experiments were established for each system featuring whole-plot treatments of a foliar fungicide and split-plot treatments of 12 cultivars. The study was conducted for 3 yr at the Wheat Pasture Res. Ctr. near Marshall, OK. Dual-purpose experiments were generally grazed from November through February. Yield in the grain-only system improved 18.8 kg ha^-1 yr^-1, equivalent to 1.3% of the mean yield for Turkey. The rate of progress in the dual-purpose system was significantly lower at 11.3 kg ha^-1 yr^-1, equivalent to 0.9% of the mean for Turkey. Management for grazing had a more profound influence on estimates of yield improvement than did management for disease protection. Linear trends in test weight were not evident under either system, nor were cultivar differences influenced by management system consistently across years. Breeding practices should emphasize selection for grain yield in both environments if future progress is to be maximized in both.Peer reviewedPlant and Soil SciencesAnimal Scienc