Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “wheat”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,081 records · Page 60Linked to original sources
PubMed2006

Selective disruption of wheat secondary metabolism by herbicide safeners.

In wheat (Triticum aestivum L.), treatment with herbicide safeners enhances the expression of enzymes involved in pesticide detoxification and reduces crop sensitivity to herbicides. Since these same enzymes are involved in plant secondary metabolism, it was of interest to determine whether or not the safener cloquintocet mexyl perturbed phenolic metabolism in wheat seedlings. LC/ESI/MS analysis identified 14 phenolic substrates in the shoots of young wheat plants. Fragmentation imposed by collision induced dissociation identified specific C-glycosidic conjugates of 4',5,7-trihydroxflavone (apigenin), 3',4',5,7-tetrahydroxyflavone (luteolin) and 3'-O-methylluteolin. Treatment of 7-day-old wheat shoots with cloquintocet mexyl resulted in an accelerated depletion of the conjugates of all three flavones, most notably with the glycosides of luteolin. In contrast, safener treatment caused the selective accumulation of 4',5,7-trihydroxy-3',5'-dimethoxyflavone (tricin) and the phenylpropanoid ferulic acid. Changes in phenolic content were associated with an increase in O-methyltransferase and C-glucosyltransferase activity toward flavonoid substrates as well as the classic enhancement of detoxifying glutathione transferases. Our results suggest that in addition to altering the capacity of wheat to metabolise herbicides and other xenobiotics, safeners can also cause a selective shift in the metabolism of endogenous phenolics.

Chromatography, Liquid↗
PubMed2006

Wheat cells accumulate a syringyl-rich lignin during the hypersensitive resistance response.

The stem rust fungus Puccinia graminis f.sp. tritici is an obligately biotrophic pathogen attacking wheat (Triticum aestivum). In compatible host/pathogen-interactions, the fungus participates in the host's metabolism by establishing functional haustoria in the susceptible plant cells. In highly resistant wheat cultivars, fungal attack is stopped by a hypersensitive response of penetrated host cells. This mechanism of programmed cell death of single plant cells is accompanied by the intracellular accumulation of material with UV-fluorescence typical of phenolic compounds. A similar reaction can be induced in healthy wheat leaves by the application of a rust-derived elicitor. We analysed the biochemical composition of this defense-induced phenolic material. Contents of total soluble and cell wall esterified and etherified phenolic acids were determined in rust-inoculated and elicitor-treated leaves of the fully susceptible wheat cultivar Prelude and its highly resistant, near-isogenic line Prelude-Sr5. While no resistance-related changes occured in any of these fractions, the lignin content as determined by the thioglycolic acid and the acetyl bromide methods increased after elicitor treatment. Nitrobenzene oxidation revealed that the entire increase can be explained by an increase in syringyl units only. These biochemical data were confirmed by fluorescence emission spectra analyses which indicated a defense-induced enrichment of syringyl lignin for cell wall samples both from elicitor-treated wheat leaves and single host cells undergoing a hypersensitive response upon fungal penetration.

Basidiomycota↗
PubMed2005

Bioavailability of diuron in soil containing wheat-straw-derived char.

This study evaluated the bioavailability of diuron in soil as influenced by char arising from the burning of wheat straw. The wheat char was a highly effective sorbent for diuron. The presence of 1% wheat char in soil resulted in a 7-80 times higher diuron sorption. A 10-week incubation resulted in <40% of 0.5 mg/kg diuron in 0.5% char-amended soil microbially degraded, as compared to 50% in char-free soil under the same conditions. Over the experimental range of diuron application rates from 0 to 12 mg/kg and of char contents from 0% to 1.0%, a 4-week bioassay indicated that both the barnyardgrass survival rating and the fresh weight of aboveground biomass decreased with increasing diuron application at given char contents but increased with increasing char content at potentially damaging diuron application rates. Residual analyses of bioassayed soils showed that the soils with char contents of 0.5% and higher and diuron application rates of 3.0 mg/kg and higher, as compared to those with no or low (0.05%) char and a diuron application rate of 1.5 mg/kg, had higher residual diuron levels but higher barnyardgrass survival ratings and fresh weights. These results suggest that enhanced sorption of diuron in soil in the presence of wheat char reduced the bioavailability of diuron, as manifested by reduced microbial degradation of diuron and its herbicidal efficacy to barnyardgrass. This study may have greater implication than for burning of wheat straw that field burning of vegetations may reduce bioavailability of pesticides.

Adsorption↗
PubMed2006

Genetic engineering of wheat--current challenges and opportunities.

Wheat is one of the major staple food crops grown worldwide; however, productivity in cereal crops has not kept pace with the world population growth. A significant increase in wheat production (>40% by 2020) is needed simply to keep up with the growing demand. This increase is unlikely to be achieved by conventional plant breeding methods because of the limited gene pool available. The application of recombinant techniques to improve wheat quality and yield is not only desirable but also has potential to open up new opportunities. Although there has been significant progress in developing gene-transformation technologies for improving these traits, this remains an important challenge for plant biotechnology. Obstacles to translate the full potential of the genomic era to wheat breeding include the need to develop elite wheat varieties without selectable markers, introducing minimal or nil intergenic DNA and social and market issues concerning genetically engineered food products.

Breeding↗
PubMed2004

Resistance in wheat to Fusarium infection and trichothecene formation.

The state of the art in Fusarium head blight resistance research is reviewed with reference to breeding for genetic resistance to Fusarium in wheat in practice. Fusarium graminearum and F. culmorum produce the trichothecene mycotoxin deoxynivalenol (DON). DON has phytotoxic properties and is an important aggressiveness factor in head blight. Head blight resistance in wheat is not specific for either F. graminearum or F. culmorum. Resistance components include resistance to penetration, resistance to colonization and mechanisms that influence kernel DON content. The resistance to Fusarium in wheat is a quantitative trait with relative high heritability and controlled by a few genes with major effect. A major quantitative trait locus (QTL) for head blight resistance from the Chinese variety Sumai 3 has been identified and verified by several research groups via molecular marker analysis. Research is now directed at identifying additional QTLs to make accumulation of resistance genes in elite wheat lines possible. The policy of official variety list trials may affect the head blight resistant level of future wheat varieties by excluding candidate varieties that are a too susceptible to Fusarium. A higher level of Fusarium head blight will guarantee lower risks for the farmer of crop loss due to reduced grain yield, low quality and mycotoxin contamination.

Crosses, Genetic↗
PubMed2004

Functional replacement of Wheat streak mosaic virus HC-Pro with the corresponding cistron from a diverse array of viruses in the family Potyviridae.

Helper component-proteinase (HC-Pro) of Wheat streak mosaic virus strain Sidney 81 (WSMV-Sidney 81) was systematically replaced with the corresponding cistron derived from four strains of WSMV (Type, TK1, CZ, and El Batán 3), the tritimovirus Oat necrotic mottle virus (ONMV), the rymoviruses Agropyron mosaic virus (AgMV) and Hordeum mosaic virus (HoMV), or the potyviruses Tobacco etch virus (TEV) and Turnip mosaic virus (TuMV). These HC-Pro proteins varied in amino acid sequence identity shared with HC-Pro of WSMV-Sidney 81 from high (strains of WSMV at approximately 86-99%) to moderate (ONMV at 70%) to low (rymoviruses and potyviruses at approximately 15-17%). Surprisingly, all chimeric viral genomes examined were capable of systemic infection of wheat upon inoculation with RNA transcripts produced in vitro. HC-Pro replacements derived from tritimoviruses did not alter host range relative to WSMV-Sidney 81, as each of these chimeric viruses was able to systemically infect wheat, oat, and corn line SDp2. These results indicate that differences in host range among tritimoviruses, including the inability of ONMV to infect wheat or the inability of WSMV strains Type and El Batán 3 to infect SDp2 corn, are not determined by HC-Pro. In contrast, all chimeric viruses bearing HC-Pro replacements derived from rymoviruses or potyviruses were unable to infect SDp2 corn and oat. Collectively, these results indicate that HC-Pro from distantly related virus species of the family Potyviridae are competent to provide WSMV-Sidney 81 with all functions necessary for infection of a permissive host (wheat) and that virus-host interactions required for systemic infection of oat and SDp2 corn are more stringent. Changes in symptom severity or mechanical transmission efficiency observed for some chimeric viruses further suggest that HC-Pro affects virulence in WSMV.

Amino Acid Sequence↗
PubMed1998

Determination of trichothecene mycotoxins in wheat by use of supercritical fluid extraction and high-performance liquid chromatography with diode array detection or gas chromatography with electron capture detection.

The extraction behaviour of the Fusarium mycotoxin deoxynivalenol (DON) and some related type B trichothecenes from spiked seasand, spiked wheat flour and naturally contaminated wheat flour with modified supercritical CO2 has been investigated and optimized under several conditions. The extraction fluid was decompressed over a solid-phase trap and the amount of deposited analytes was determined by HPLC-diode array detection (DAD) or GC-electron capture detection (ECD) without any further clean-up. Recovery rates as high as 90.1 +/- 10.7% were achieved for spiked wheat samples and 53.0 +/- 3.2% for naturally contaminated samples. The performance of the optimized supercritical fluid extraction (SFE) method was compared with an already well established analytical method employing extraction on a rotary shaker in combination with Mycosep clean-up. Moreover, the SFE procedure developed for naturally DON contaminated wheat was employed for the simultaneous extraction of 5 type B trichothecenes by GC-ECD. This work represents the first successful approach in obtaining an SFE-method for the extraction of Fusarium mycotoxins from wheat with reasonable recoveries and good precision.

Chromatography, Gas↗
PubMed2000

Impact of environmental factors on fungal respiration and dry matter losses in wheat straw.

An automatic electrolytic respirometer enabled replicated determinations of the respiration rates of individual fungi on sterile straw, and the mixed mycoflora of naturally contaminated wheat straw at different steady-state temperatures (10-30 degrees C) and water activities (a(w), 0.75-0.98) over periods of 8-14 days. Generally, the respiratory activity of individual spoilage fungi (Alternaria alternata, Cladosporium cladosporioides, Eurotium amstelodami, Fusarium culmorum and Penicillium aurantiogriseum) on sterile wheat straw increased linearly with increasing a(w) at 25 degrees C. The calculated maximum dry matter loss of wheat straw due to colonisation by individual species was about 10%, regardless of a(w). On naturally contaminated wheat straw fungal activity was also related to temperature and a(w), with maximum respiration at 30 degrees C and 0.98 a(w). At the lowest temperature examined, 10 degrees C, there was a slight lag prior to respiratory activity occurring. The respiratory activity was also significantly reduced (by half) when available water was reduced to 0.95-0.90 a(w). In contrast to the colonisation of sterile straw by individual species, the maximum dry matter loss caused by fungal deterioration of naturally contaminated wheat straw was 3.4% at 0.98 a(w) and 30 degrees C. The dominant fungal genera and species varied with a(w) and temperature. These results are discussed in relation to the storage of cereal straw without spoilage.

Journal Article↗
PubMed2001

Effects of fulvic acid on the bioavailability of rare earth elements and GOT enzyme activity in wheat (Triticum aestivum).

Fulvic acid (FA) was extracted and purified from natural soil and the effects of such FA on the bioaccumulation of rare earth elements (REEs, La3+, Gd3+ and Y3+) in wheat seedling were investigated. The results indicated that low concentration of FA (<0.4 mg C/l to root, <0.7 mg C/l to tops (stem and leaves)) could increase the bioaccumulation values of REEs in wheat, but when the concentration of FA was high (>0.4 mg C/l to root, >1.5 mg C/l to tops) the bioaccumulation values were decreased. Kinetic experimental results suggested that bioaccumulation values of REEs in roots for 30 days were correlated with the kinetic linear growth equation, and correlation coefficients were higher than 0.861. The kinetic bioaccumulation pattern of REEs in tops was different from that in root. The bioaccumulation values of REEs in wheat root were much higher than in wheat tops. Variations of glutamic oxaloacetic transaminase (GOT) enzyme activities in wheat root and tops were determined. A good correlation existed between the bioaccumulation values of REEs and GOT enzyme activities, and the correlation coefficients were higher than 0.922. GOT is an important parameter influencing the bioavailability of REEs.

Aspartate Aminotransferases↗
PubMed2001

Impacts of climate change and climate variability on the competitiveness of wheat and beef cattle production in Emerald, north-east Australia.

Emerald, north-east Queensland, is at the northern margin of the wheat cropping region of Australia. The Emerald region was previously used predominantly for grazing beef cattle; however, cropping has developed in importance over the past 30 years. We use historical climate records (1890-1998) to simulate and compare wheat yields, grass production and live-weight gain (LWG) over time. The cropping expansion from the 1970s to the early 1990s has occurred in a unique period in the 108-year record with the highest average wheat yields, lowest wheat yield variability and the greatest relative productivity of wheat production against grass production. If this window of opportunity is a result of long-term climate variability, then cropping is likely to decline in the region as conditions return to those experienced earlier in the record. If this increase is related to climate change, then cropping is likely to persist in the region with productivity maintained at current levels particularly through the yield-enhancing effects of increased atmospheric CO2 concentrations. However, this persistence will be influenced by the frequencies of El Niño conditions that may increase with global warming. The high relative productivities experienced over the past few decades have probably biased producers' expectations, and applications for drought support need to take into account the longer-term perspective provided by this analysis. Nevertheless, the last 6 years have the lowest simulated mean LWG production on the record. The identification of poor production periods depended on the production element being addressed and the timescale involved.

Agriculture↗
PubMed2001

Cloning of new members of heat shock protein HSP101 gene family in wheat (Triticum aestivum (L.) Moench) inducible by heat, dehydration, and ABA(1).

We have cloned two cDNAs, TaHSP101B and TaHSP101C, encoding two heat stress-inducible members of HSP101/ClpB family in bread wheat (Triticum aestivum (L.) Moench.). Proteins encoded by these cDNAs are highly similar at the primary sequence level and diverged from the previously reported TaHSP101 (designated TaHSP101A) both in the consensus ATP/GTP-binding region II and in the carboxy terminal region. The HSP101 gene was determined to be a single copy gene or a member of a small gene family in hexaploid wheat. Messages encoding HSP101 proteins were inducible by heat stress treatments in both wheat leaves and roots. Accumulation of the TaHSP101C mRNA was less abundant than that of TaHSP101B mRNA. We are showing for the first time that in addition to heat stress, expression of HSP101 mRNAs in wheat leaves was induced by a 2-h dehydration and a treatment with 5x10(-5)M ABA, but not affected by chilling or wounding, indicating that HSP101 proteins may be involved in both heat and drought responses in wheat.

Abscisic Acid↗
PubMed1999

Isolation of a zeta class wheat glutathione S-transferase gene.

A new Zeta class glutathione S-transferases (GST) gene, pGST, has been cloned from wheat for the first time by the differential display PCR (DD-PCR) method. The genomic sequence of pGST, TA-GSTZ1, contains nine exons that encode a polypeptide of 213 amino acids and eight introns. The deduced amino acid sequence of TA-GSTZ1 as well as the exon:intron placement are more similar to the GSTs of the Zeta class than to the two wheat GSTs reported earlier. The pGST cDNA gene product expressed in Escherichia coli and purified by affinity chromatography showed typical Zeta class GST and glutathione peroxidase activities. Sequence polymorphism in the 3' untranslated region (UTR) of TA-GSTZ1 gene in wheat has been discovered. In this study, an 89 bp sequence is present in the 3' UTR of TA-GSTZ1gene in 16 wheat cultivars but absent in the other five. Although the biological importance of this polymorphism is unknown, it can be useful as a genetic marker in wheat breeding.

Amino Acid Sequence↗
PubMed1998

Relationships among deoxynivalenol, ergosterol and Fusarium exoantigens in Canadian hard and soft wheat.

Soluble extracellular components (exoantigens) from cultures of Fusarium graminearum and F. sporotrichioides were used to produce antisera from chickens for an indirect enzyme immunoassay. This immunoassay was used to estimate Fusarium exoantigen levels in 40 samples of fusarium head blight-infected hard red spring wheat from Manitoba, and in 50 samples of infected soft white winter wheat from Ontario. These wheat samples were also assayed for deoxynivalenol (DON), the predominant Fusarium mycotoxin, and for ergosterol, a metabolite reflecting fungal biomass. Using F. sporotrichioides antisera, the linear correlations between exoantigen level and DON content for the hard and soft wheats had coefficients of 0.80 and 0.76, respectively. With the same antisera, linear correlations between exoantigen level and total ergosterol concentration for the hard and soft wheats had coefficients of 0.66 and 0.81, respectively.

Antigens, Fungal↗
PubMed2006

Study on homoeologous chromosome pairing and translocation induced by 5A/5R X 6A/6R wheat-rye substitution lines.

This article aims to study the homoeologous chromosome pairing and translocation induced by 5A/5R x 6A/6R wheat-rye substitution lines. To clarify the mechanism of homoeologous chromosome pairing and create wheat-rye translocation lines, two wheat-rye substitution lines, 5A/5R and 6A/6R were crossed. The chromosome behavior of pollen mother cells (PMCs) in meiosis was investigated in hybrid F1. Homoeologous chromosome pairing between wheat and rye occurred in 22.91% of PMC. Wheat-rye translocation lines were identified via C-banding and in situ hybridization (GISH) in hybrid F2 and later generations. In F2 generation, translocations happened in 9 of 45 plants, reached to 20%. These translocation lines were generated from homoeologous chromosome pairing, or mis-division and reconstruction of univalent chromosomes.

Chromosome Banding↗
PubMed2002

Soybean hulls, wheat middlings, and corn gluten feed as supplements for cattle on forage-based diets.

Soybean hulls, wheat midds, and corn gluten feed are viable alternative supplements for forage-fed cattle. All three result from the processing of major Unites States agricultural crops, so large supplies are available. Their value is better for ruminant animals than for monogastrics because they contain digestible fiber components. These byproducts are widely available throughout the Unites States and will generally be more economical than traditional feed grains or commercial feeds when used appropriately as supplements to forage-based diets. Knowledge about the composition of base forage must be used in planning supplementation strategies because base forages vary in protein and mineral content [9]. Soybean hulls alone may be a good selection in situations in which forages are adequate or high in protein. In situations where forage is marginal or deficient in protein, wheat midds, corn gluten feed, or a mix of soybean hulls and corn gluten feed might be most desirable. All three feeds can be variable in nutrient composition, so they should be analyzed to ensure a balanced nutrient level in diets. Soybean hulls are especially variable in crude protein content and should always be analyzed when forages are marginal or deficient in protein. Despite the fact that published energy levels are substantially lower, research has shown that soybean hulls and wheat midds have a value comparable to corn and soybean meal in forage-based diets. Corn gluten feed has also been comparable to corn and soybean meal in most reports but is closer in value to its published energy levels. In general, results with soybean hulls have been surprisingly good and consistent, whereas responses to wheat midds and corn gluten feed supplementation have been more variable and sometimes disappointing. Feeding rates for soybean hulls can range from low to extremely high depending on forage availability and desired performance. Wheat midds should be limited in most situations to 50% of the expected dry matter intake because of their rapidly digested starch content. Corn gluten feed should be limited to approximately 50% of expected dry matter intake because of its high sulfur content. Several research groups are currently evaluating self-feeding programs for these byproducts, and while the potential for health and production problems exist, results have been encouraging in most cases. Self-feeding would reduce the labor costs of hand feeding and could provide backgrounders with a program to expand cattle numbers on a limited land base.

Animal Feed↗
PubMed2003

Use of xylan, an agricultural by-product, in wheat gluten based biodegradable films: mechanical, solubility and water vapor transfer rate properties.

The possibility of using xylan, as an agricultural by-product, for production of composite films in combinations with wheat gluten was investigated. Different levels of xylan (0-40% w/w) were incorporated into wheat gluten to form biodegradable composite films. Films were prepared at pH 4 and 11, and dried at either uncontrolled or controlled conditions. The mechanical properties, solubilities and water vapour transfer rate (WVTR) of the composite films were studied. Films were obtained with added xylan without decreasing film-forming quality. Xylan can be used as an additive, as much as 40% (w/w), in wheat gluten films. Changing pH, wheat gluten/xylan ratio, xylan type and drying conditions affected mechanical and solubility properties, however, WVTR was not affected by xylan additions. Wheat gluten/xylan composite films having different characteristics can be produced depending on xylan type, composition and process conditions.

Agriculture↗
PubMed2000

Stabilization effect of zeolite on DHFR mRNA in a wheat germ cell-free protein synthesis system.

The effects of zeolites and monocations on the protein synthesis in a cell-free system derived from wheat germ were investigated. M type of synthetic zeolite markedly enhanced the translation efficiency. Whereas this kind of stimulatory effect of zeolite in an Escherichia coli cell-free system resulted from a change in the salt compositions of the reaction solution with the addition of zeolite, the enhancement of protein synthesis in a wheat germ cell-free system was not due to the ion exchange reaction of zeolites. From the results of mRNA stability analysis, it was found that zeolite could stabilize the mRNA in a wheat germ cell-free protein synthesis system. The stabilization of mRNA by the simple addition of zeolites is useful for the enhancement of protein synthesis in a wheat germ cell-free system, since conventional methods to improve mRNA stability, such as the addition of nuclease inhibitor, have not been effective for a wheat germ cell-free system.

Journal Article↗
PubMed2003

Effect of organic and mineral fertilizers on N-use by wheat under different irrigation frequencies.

A field trial was established in Errachidia, southern Morocco, to investigate the interaction between wheat residue management and mineral 15N-labelled ammonium sulphate, under different irrigation treatments, applied to wheat (Triticum durum var. Karim). In treatments I1, I2, I3 and I4, plots were irrigated every 10, 15, 21 and 30 days. Each plot contained three sub-plots that received three fertilization treatments: T1 received 42 kg N ha-1 of ammonium sulphate before seedling, 42 kg N ha-1 of ammonium sulphate labelled with 9.764 at % 15N excess at tillering and 84 N kg ha-1 of ammonium sulphate at flowering; T2 received 42 kg N ha-1 of ammonium sulphate labelled with 9.764 at % 15N excess at seedling, 42 kg N ha-1 at tillering and 42 kg N ha-1 at flowering; T3 received 4800 kg ha-1 of wheat residue labelled with 1.504 at % 15N excess and 42 kg N ha-1 of ammonium sulphate before seedling and 42 kg N ha-1 of ammonium sulphate at flowering. Nitrogen fertilization with 168 kg N ha-1 did no significantly increase grain and straw yields in comparison to the 126 kg N ha-1 application. The combination of the organic input and supplementary application of mineral fertilizer N has been found as a more attractive management option. For all irrigation treatments, the % recovery of N in the whole plant was higher in plants that received 15N at tillering (63%, 49% respectively for irrigation intervals between 10 and 30 d) than in plants that received 15N just after seeding (28% for irrigation each 10- and 30-d intervals). For the irrigation treatment each 10 and 15 days, the 15N was mainly recovered by the grain for all fertilization treatments, whereas for irrigation treatment each 30 days, the grain and straw recovered nearly equal amounts of fertilizer. For grain and straw of wheat, nitrogen in the plant derived from the fertilizer was low, while most of the N was derived from the soil for all irrigation and fertilization treatments. The % nitrogen in the plant derived from the fertilizer values showed no significant difference between the different plant parts. The results suggested a dominant influence of moisture availability on the fertilizer N uptake by wheat. Under dry conditions the losses of N can be allotted to denitrification and volatilisation.

Agriculture↗