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PubMed1997

Presence of wheat retrotransposons in Gramineae species and the origin of wheat retrotransposon families.

Distribution of wheat retrotransposon families (families 1 to 7) was examined in 11 Gramineae species by the use of representative reverse transcriptase domain clones selected from six of the seven wheat retrotransposon families previously identified as probes. The homologues of families 3, 4, 5, and 7 retrotransposons were detectable only in the Pooideae species, suggesting that the distribution of the retrotransposons related to these families is restricted to the Pooideae subfamily. The representatives of families 1 and 2, distantly related to families 3 to 7, revealed homologues additionally in the species outside the Pooideae subfamily including rice. These results suggest that the retrotransposons related to the former families have wider distribution than those related to families 3, 4, 5, and 7. Analysis of a wheat genomic clone confirmed that the family 1 representative reverse transcriptase domain clone is a Ty1-copia group retrotransposon derivative, which we have named Tar1. On the basis of these results, the origin of wheat retrotransposon families is discussed.

Amino Acid Sequence↗
PubMed2005

Selenium distribution in wheat grain, and the effect of postharvest processing on wheat selenium content.

Selenium (Se) is an essential micronutrient for animals and humans, and wheat is a major dietary source of this element. It is important that postharvest processing losses of grain Se are minimized. This study, using grain dissection, milling with a Quadrumat mill, and baking and toasting studies, investigated the distribution of Se and other mineral nutrients in wheat grain and the effect of postharvest processing on their retention. The dissection study, although showing Se concentration to be highest in the embryo, confirmed (along with the milling study) previous findings that Se (which occurs mostly as selenomethionine in wheat grain) and S are more evenly distributed throughout the grain when compared to other mineral nutrients, and, hence, lower proportions are removed in the milling residue. Postmilling processing did not affect Se concentration or content of wheat products in this study. No genotypic variability was observed for grain distribution of Se in the dissection and milling studies, in contrast to Cu, Fe, Mn, and Zn. This variability could be exploited in breeding for higher proportions of these nutrients in the endosperm to make white flour more nutritious. Further research could include grain dissection and milling studies using larger numbers of cultivars that have been grown together and a flour extraction rate of around 70%.

Animals↗
PubMed2005

Yield response and categories of resistance to Russian wheat aphid in four Dn4 hard red winter wheat cultivars.

A field experiment was conducted to determine whether resistance to Russian wheat aphid, Diuraphis noxia (Mordvilko), conferred by the Dn4 gene is affected by genetic background. This was done by comparing the yield responses to Russian wheat aphid-resistant wheat containing Dn4, derived through the backcross method, to those of the corresponding recurrent parents. Infested resistant cultivars had fewer Russian wheat aphids per tiller than infested susceptible cultivars at the Lamar and Fort Collins, CO sites but not at the Akron, CO site. At the Lamar site, resistant cultivars yielded more than the susceptible cultivars. 'Prairie Red' and 'Yumar' were more resistant than 'Prowers', especially at the higher infestation level. Resistance in these cultivars was categorized in a laboratory experiment to confirm this differential expression of resistance. Resistance in Prairie Red, 'Halt', 'Prowers 99', and Yumar was categorized at three plant growth stages. Antibiosis was expressed as reductions in maximum number of nymphs produced per 24 h and intrinsic rate of increase. The maximum number of nymphs produced per 24 h was reduced in Halt and 'Lamar'. Averaged over cultivars, the intrinsic rate of increase was less at jointing than at the seedling or tillering growth stages. Tolerance was expressed in the resistant cultivars as reduced chlorosis and leaf rolling. Growth reductions in infested Prowers 99 plants was less than the other cultivars. This study confirms that some cultivars containing Dn4 may express antibiosis and tolerance, whereas others may not show the same categories. Thus, expression is affected by genetic background.

Animals↗
PubMed2006

Resistance to biotype 2 Russian wheat aphid (Homoptera: Aphididae) in two wheat lines.

Biotype 2 of the Russian wheat aphid, Diuraphis noxia (Mordvilko), was identified in the United States in 2003 and is virulent to all commercially available cultivars of winter wheat, Triticum aestivum L., that are resistant to biotype 1. We compared the development and reproduction of biotype 2 D. noxia at 21.7 +/- 0.12 degrees C on 'Trego' (PI 612576), a susceptible commercial cultivar, and on lines CI 2401 and 03GD1378027 that represent putative resistance sources. CI 2401 is a pure wheat line originating in the former USSR (Tajikistan), whereas 03GD1378027 is a USDA-ARS breeding line originally developed from crosses with a South African line that carried a large rye translocation conferring D. noxia resistance. Both lines previously showed resistance to biotype 1 and are currently being used in the development of D. noxia-resistant wheat cultivars. Both solitary apterous virginoparae of biotype 2 and their progeny experienced a reduction in survival and prolonged developmental times on CI 2401 and 03GD1378027 compared with Trego, but the former lines did not differ significantly from each other with respect to either measure of aphid performance. Progeny developed faster than did their foundress mothers on CI 2401 and Trego, but not on 03GD1378027. Mean foundress fecundity did not differ between CI 2401 and 03GD1378027 but was reduced on these lines relative to Trego. Foundresses also were more often found off plants of CI 2401 and 03GD1378027 than Trego. Estimates of intrinsic rate of increase were higher on Trego than on either CI 2401 or 03GD1378027, the latter two lines yielding similar values. The negative impacts of CI 2401 and 03GD1378027 on development and reproduction of biotype 2 indicate that these lines represent sources of resistance effective against this biotype.

Animals↗
PubMed2006

Categories and inheritance of resistance to Russian wheat aphid (Homoptera: Aphididae) biotype 2 in a selection from wheat cereal introduction 2401.

The Russian wheat aphid, Diuraphis noxia (Kurdjumov) (Homoptera: Aphididae), is one of the most devastating insect pests of wheat (Triticum spp.) and barley (Hordeum spp.) in the world. Yield losses and control costs are valued at several hundred million dollars each year. The use of D. noxia-resistant cultivars is an ecologically, economically, and biologically sound method of managing this pest. Several D. noxia resistance (Dn) genes from wheat have been used to develop cultivars resistant to D. noxia. However, a new U.S. D. noxia biotype (biotype 2) in Colorado is virulent to all known Dn genes except the Dn7 gene from rye (Secale spp.). Hence, there is an immediate need to identify and characterize unique sources of D. noxia resistance to biotypes. In this article, we report resistance to D. noxia biotype 2, identified in a selection from wheat cereal introduction (CItr) 2401, that is controlled by two dominant genes. CItr2401 has a strong antibiosis effect that is exhibited as a reduced intrinsic rate of increase of D. noxia biotype 2. CItr2401 plants also exhibit tolerance to leaf rolling and chlorosis. No antixenosis was detected in CItr2401.

Animals↗
PubMedDate not supplied

[The hybridization of tetraploid wheat with the octoploid wheat-wild rye amphiploid Elytricum fertile and the chromosome behavior in meiotic MI].

The hybridization and chromosome behaviour regularities at meiotic MI of reciprocal F1 hybrids of tetraploid wheats T. durum and T. turgidum with 56-chromosome incomplete wheat-Elymus amphiploid (IWEA) Elytricum fertile, were investigated. Variation of main indices of the hybridization has been revealed to be determined by variance of such factors as cross direction, genotype peculiarities of wheat strains and their interaction. Elymus sibiricus genome, contained in IWEA karyotype, carries several genes, that can suppress wheat diploidization system. Reduction of homologous chromosome synapsis is not determined by these genes, but is connected with influence of other Elymus sibiricus chromosome factors.

Chromosomes↗
PubMed2002

[Molecular analysis of leaf-rust resistant introgression lines obtained by crossing hexaploid wheat Triticum aestivum with tetraploid wheat Triticum timopheevii].

Twenty-four Triticum eastivum x T. timopheevii hybrid lines developed on the basis of five varieties of common wheat and resistant to leaf rust were analyzed by the use of microsatellite markers specific for hexaploid common wheat T. aestivum. Investigation of intervarietal polymorphism of the markers showed that the number of alleles per locus ranged from 1 to 4, depending on the marker (2.5 on average). In T. timopheevii, amplification fragments are produced by 80, 55, and 30% of primers specific to the A, B, and D common wheat genomes, respectively. Microsatellite analysis revealed two major areas of introgression of the T. timopheevii genome: chromosomes of homoeological groups 2 and 5. Translocations were detected in the 2A and 2B chromosomes simultaneously in 11 lines of 24. The length of the translocated fragment in the 2B chromosome was virtually identical in all hybrid lines and did not depend on the parental wheat variety. In 15 lines developed on the basis of the Saratovskaya 29, Irtyshanka, and Tselinnaya 20, changes occurred in the telomeric region of the long arm of the 5A chromosome. Analysis with markers specific to the D genome suggested that introgressions of the T. timopheevii genome occurred in chromosomes of the D genome. However, the location of these markers on T. timopheevii chromosomes is unknown. Our data suggest that the genes for leaf-rust resistance transferred from T. timopheevii to T. aestivum are located chromosomes of homoeological group 2.

Chromosomes↗
PubMed2004

[Effect of potassium application stage on photosynthetic characteristics of winter wheat flag leaves and on starch accumulation in wheat grains].

In this study, the same amount of potassium was applied as basal dressing (treatment 1) and as basal dressing and top-dressing at jointing stage (treatment 2). The results showed that treatment 2 improved the photosynthetic rate and sucrose-phosphate synthase (SPS) activity of winter wheat flag leaves and the adenosine diphosphate glucose pyrophosphortlase (ADPGPPase) activity in wheat grains. It increased the supplying strength of sucrose and the accumulation rate of starch in the grain, and also, the grain yield. Both of the treatments improved the synthesis capacity of sucrose in wheat flag leaf and the transformation capacity from sucrose to starch in wheat grain, die to the coordinative relationship between source and sink of starch synthesis, including the synthesis, transport and transformation of photosynthate.

Biomass↗
PubMed2004

[Molecular study and C-banding of chromosomes in common wheat alloplasmic lines obtained from the backcross progeny of barley-wheat hybrids Hordeum vulgare L. (2n = 14) x Triticum aestivum L. (2n = 42) and differing in fertility].

We studied common wheat alloplasmic lines differing in fertility traits, which had been obtained from the backcross progeny of barley-wheat hybrids Hordeum vulgare L. (2n = 14) x Triticum aestivum L. (2n = 42), using molecular analysis and chromosome C-banding. It was found that the nuclei of all alloplasmic lines studied, regardless of their fertility traits, contained only the common wheat chromosomes (2n = 42). The formation of line L-79(10)(3)F6, stable for self-fertility, from line L-79(10)(3)F6 was accompanied by changes of the proportions of simple sequence repeats of the parental common wheat varieties in the nuclear genome. The presence of barley genome fragments in line accessions with incomplete self-fertility was shown by RAPD. Heteroplasmy for mitochondrial genome loci was detected in these lines with the use of primers specific to the tMet-18S-5S repeat of mitochondrial ribosomal genes.

Chimera↗
PubMed2004

Clinostating effects on Apogee wheat resistance to wheat streak mosaic virus.

The effects of vertical and horizontal clinostating with container velocity 2 rpm and platform velocity 1 rpm on Apogee wheat resistance to wheat streak mosaic virus (WSMV) were studied. For the first time the yield of grain was obtained from both, healthy and the WSMV-infected wheat plants under conditions of simulated microgravity (clinorotation) which is accounted for by the inclusion of various mechanisms in the process of plant adaptation to the factors of stresses. For the first time the stages of viral infection development were elucidated under the conditions of prolonged clinostating and the presence of the WSMV was detected in wheat plants on the 18th day after inoculation employing the method of polymerase chain reaction (PCR). In the test variant with vertical clinostating (R=1,0) the least favorable conditions for viral reproduction were identified. In the same variant the increases of the total nitrogen content in the ears were observed which may be an evidence of interferon-like protein synthesis in plant similar to the interferon system functioning in animals.

Biomass↗
PubMed1989

Sequence variability in three wheat germ agglutinin isolectins: products of multiple genes in polyploid wheat.

Three highly homologous wheat germ isolectins (95-97%) are distinct gene products in hexaploid wheat. The amino acid sequences of two of these [wheat germ agglutinin 1 (WGA1) and 2 (WGA2)] are compared with sequence data derived from a complementary DNA (cDNA) clone for the third isolectin (WGA3). This comparison includes three corrections to earlier amino acid sequence data of both WGA1 and WGA2 at positions 109 (from Ser to Phe), 134 (from Gly to Lys), and 150 (from Gly to Trp). These reassignments are based on new results from crystal structure refinement and amino acid sequence data of WGA1, as well as the recently determined nucleotide sequence of WGA3. In addition, the C-terminal residue of WGA1 has been revised to Gly171 and now differs from WGA2 (Ala171). Four other positions, Asn9, Ala53, Gly119, and Ser123, at which WGA1 and WGA2 are identical but differ from the DNA sequence of WGA3, were also reinvestigated by amino acid sequencing techniques and confirmed. Variability among the three isolectins is observed at a total of 10 sequence positions: 9, 53, 56, 59, 66, 93, 109, 119, 123, and 171. Pairwise comparisons indicate that WGA3 deviates to a much larger extent from WGA1 (at eight positions) and from WGA2 (at seven positions) than the latter from one another (at five positions). Eight of the 10 mutations are equally distributed between domains B and C, the two interior and more highly conserved of the four WGA domains (A, B, C, D). Correlation of the variable residues with the three-dimensional structure indicates that all except the two previously described B-domain residues, 56 and 59 (Wright and Olafsdottir 1986), are easily accommodated at the dimer surface. WGA3 displays a higher degree of inter-domain similarity than found in WGA1 and WGA2. Of the seven variable positions that are located in the domain core (residues 3-31), five are in perfect agreement with our earlier predicted domain ancestor sequence. This suggests that of the three isolectins WGA3 is most closely related to the common ancestral molecule.

Amino Acid Sequence↗
PubMed1982

Immunocytochemical localization of wheat germ agglutinin in wheat.

Immunocytological techniques were developed to localize the plant lectin, wheat germ agglutinin (WGA), in the tissues and cells of wheat plants. In a previous study we demonstrated with a radioimmunoassay that the lectin is present in wheat embryos and adult plants both in the roots and at the base of the stem. We have now found, using rhodamine, peroxidase, and ferritin-labeled secondary antibodies, that WGA is located in cells and tissues that establish direct contact with the soil during germination and growth of the plant In the embryo, WGA is found in the surface layer of the radicle, the first adventitious roots, the coleoptile, and the scutellum. Although found throughout the coleorhiza and epiblast, it is at its highest levels within the cells at the surface of these organs. In adult plants, WGA is located only in the caps and tips of adventitious roots. Reaction product for WGA was not visualized in embryonic or adult leaves or in other tissues of adult plants. At the subcellular level, WGA is located at the periphery of protein bodies, within electron-translucent regions of the cytoplasm, and at the cell wall-protoplast interface. Since WGA is found at potential infection sites and is known to have fungicidal properties, it may function in the defense against fungal pathogens.

Cell Wall↗
PubMed2004

[Wheat germ agglutinin participates in regulation of cell division in apical root meristem of wheat seedlings].

A study was made of cell division activity and hormonal status in roots of 4 day old wheat seedling treated with wheat germ agglutinin (WGA). The revealed stimulating effect of WGA on mitotic index (MI) and cell area in root extension zone was specific for this lectin, because gliadin, taken as a control protein, caused no changes in growth parameters. Phytolectins (phytohemagglutinin and concanavalin A) possessing properties of mitogens rendered no such essential influence on cell growth of wheat. Immunoassay has shown that WGA-treatment leads to accumulation of auxins and cytokinins in roots. This suggest participation of WGA in regulation of MI of meristem cells in roots of seedlings during their interaction with phytohormones.

Cell Division↗
PubMed1995

Evaluation of sensitivity of flow cytometry in detecting aneuploidy in wheat using disomic and ditelosomic wheat-rye addition lines.

Flow cytometric DNA analysis was used to study changes in nuclear DNA content induced by the addition of complete or telosomic rye chromosomes into the genome of common wheat (Triticum aestivum L.). The DNA content of each addition line was determined by comparison with an internal reference value and was expressed as a difference with respect to the original wheat parental line. A 1.84% difference in the DNA content could be detected. Nuclei were flow sorted and the presence of rye chromatin in the nuclei with the higher DNA content was demonstrated by Southern hybridization. Flow cytometry was proven to be sensitive enough to detect the small DNA content deviations that are expected to occur in aneuploid plants of wheat.

Aneuploidy↗
PubMed1978

[Biological value of wheat proteins as dependent on maturity of the wheat grain].

The authors studied the dependence of the change in biological protein value of the wheat grains upon the degree of maturity. The biological protein value (as calculated according to MITCHELL) decreases during the period of ripening and, at the time of full ripeness, it is significantly lower than in the initial stage. This decrease varies from 10.7 to 19.0%, according to wheat variety. In contrast to this, the essential amino-acid index changes but insignificantly with ripening. Virtually identical biological protein values were obtained with both methods from full-ripe wheat grains.

Amino Acids, Essential↗
PubMed1994

New cytochrome P450-dependent reactions from wheat: terminal and sub-terminal hydroxylation of oleic acid by microsomes from naphthalic acid anhydride and phenobarbital induced wheat seedlings.

Incubation of the microsomal fraction from etiolated wheat shoots (Triticum aestivum L. cv Etoile de Choisy) with [1-14C]oleic acid led to the formation of three polar metabolites which were identified as 18-, 17- and 16-hydroxyoleic acids by gas chromatography/mass spectra analysis. They were generated in a molar ratio of 1.4/4.6/4, respectively. Terminal and sub-terminal hydroxylation of oleic acid and the cytochrome P450 content were strongly enhanced in microsomes from wheat shoots treated with naphthalic acid anhydride and phenobarbital. The involvement of cytochrome P450 is demonstrated by the dependence of hydroxylation upon O2 and NADPH, and by their light-reversible inhibition by carbon monoxide. In addition, the hydroxylation of oleic acid, but not of lauric acid and cinnamic acid, was inhibited when microsomes where incubated with 9-octadecen-16-ynoic acid, a substrate analogue displaying an acetylenic function at the carbon position of major enzyme attack. Our results suggest that at least two different P450 enzymes are involved in the oxidation of oleic and lauric acids in wheat.

Cytochrome P-450 Enzyme System↗
PubMed1989

Molecular characterization of an active wheat LMW glutenin gene and its relation to other wheat and barley prolamin genes.

The isolation and characterisation by DNA sequencing of a low molecular weight (LMW) glutenin gene from wheat is described. The deduced protein contains a signal peptide, a central repetitive region rich in proline and glutamine and N and C terminal non-repetitive domains, similar to other prolamins. A detailed comparison of the C terminal domain of 20 prolamin genes enabled us to divide them into 4 families. The LMW glutenin family is distinct from the alpha, beta- and gamma-gliadin families of wheat and is closest to the B hordein genes of barley. This and other comparisons were also used to assess the pattern of genetic variation among prolamin sequences and to provide a molecular basis for the interpretation of prolamin size polymorphism. The 5' flanking fragment of the isolated gene was previously shown to direct endosperm-specific expression of a reporter gene in transgenic tobacco. Evidence is provided that the isolated gene is also active in wheat and its transcription initiation site was determined. Features of the gene which may be relevant to its activity are discussed.

Amino Acid Sequence↗
PubMed1976

[The characteristics of wheat grains. I. Exterior characteristics of the wheat grains as criterion of a type estimation (author's transl)].

Typical characteristics of the wheat types Kranich, Kormoran, Kolibri, Diplomat, Benno, Huntsman were worked out and a method for their fast estimation was developed. The characteristics of the different types were drawn in lines. Their usefulness for the estimation of wheat types out of a grain mixture of pure wheat types of unknown age and origin were successfully tested.

Triticum↗