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PubMed1983

The characterization of cDNA clones coding for wheat storage proteins.

Poly(A)+ RNA isolated from the developing wheat endosperm var. Chinese Spring, has been used as template for the construction of a cDNA library. Within the library, clones have been identified by in vitro translation of hybrid-selected mRNA which encode alpha/beta gliadin related sequences and gamma-gliadin related sequences. The DNA sequence of one such clone has been determined and it shows homology with that of a clone encoding a barley storage protein, B-hordein. The sequence includes a tandem DNA repeat which is discussed in relation to the generation of diversity within the gliadins.

Amino Acid Sequence↗

PubMed2003

Inheritance and expression of stripe rust resistance in common wheat (Triticum aestivum) transferred from Aegilops tauschii and its utilization.

Stripe rust is one of the most destructive diseases for wheat crops in China. Two stripe rust physiological strains, i.e. CYR30 (intern. name: 175E191) and CYR31 (intern. name: 293E175) have been the dominant and epidemic physiological strains since 1994. One Aegilops tauschii accession (SQ-214) from CIMMYT was found immune from or highly resistant to Chinese new stripe rust races CYR30 and CYR31 at adult stage. SQ-214 was crossed with a highly susceptible Ae. tauschii accession As-80. Analysis of data from F1-F2 populations of SQ-214/As-80 revealed that the resistance was controlled by a single dominant gene. To exploit the resistance for wheat breeding, SQ-214 was crossed with Chinese Spring (CS) and backcrossed by two Chinese commercial wheat varieties MY26 and SW3243. The resistance from SQ-214 was suppressed in the F1 hybrids (CS/SQ-214) and the F2 population of CS/SQ-214//MY26. However, the resistance of SQ-214 was expressed in several F2 individuals of CS/SQ-214//SW3243. Eleven advanced lines with high level of resistance to the Chinese stripe rust CYR30 and CYR31 have been developed. This result suggested that SW3243 does not suppress the expression of the Chinese stripe rust and should be used as wheat germplasm for exploiting resistance of Ae. tauschii in wheat breeding. The gliadin electrophoretic pattern of the eleven advanced lines with high stripe rust resistances was compared with their parents SQ-214, CS and SW3243 by acid polyacrylamide gel electrophoresis. The omega-gliadin bands of Gli-Dt1 in Ae. tauschii SQ-214 were transferred to some advanced lines and freely expressed in common wheat genetic background. One of advanced lines possesses a null Gli-D1 allele, where the omega-gliadin bands encoding by the Gli-D1 allele were absent. The potential utilization of this advanced line for wheat quality and stripe rust resistance breeding is also discussed in this paper.

Alleles↗

PubMed2005

Chromosomal assignment and deletion mapping of barley EST markers.

From about 10000 PCR-based EST markers of barley we chose 1421 EST markers that were demonstrated to be amplified differently by PCR between wheat (Triticum aestivum cv. Chinese Spring) and barley (Hordeum vulgare cv. Betzes). We assigned them to the seven barley chromosomes (1H to 7H) by PCR analysis using a set of wheat-barley chromosome addition lines. We successfully assigned 701 (49.3%) EST markers to the barley chromosomes: 75 to 1H, 127 to 2H, 119 to 3H, 94 to 4H, 108 to 5H, 81 to 6H and 97 to 7H. By using a set of Betzes barley telosomic addition lines of Chinese Spring, we could successfully determine the chromosome-arm (S or L) location of at least 90% of the EST markers assigned to each barley chromosome. We conducted a trial mapping using 90 EST markers assigned to 7HS (49) or 7HL (41) and 19 wheat lines carrying 7H structural changes. More EST markers were found in the distal region than in the proximal region.

Chromosome Deletion↗

PubMed1995

The developmental stage of inactivation of rye origin rRNA genes in the embryo and endosperm of wheat x rye F1 hybrids.

To identify the developmental stage during which the preferential inactivation of rRNA genes from the rye parent occurs in wheat x rye hybrids, nucleolar activity was evaluated in the embryo and endosperm of developing seeds of the hybrids. The hybrids were obtained from crosses of euploid and aneuploid lines of hexaploid wheat, Triticum aestivum cv. Chinese Spring, with rye, Secale cereale cv. Centeio do Alto. The number of nucleolar organizing regions (NORs) and nucleoli present in the embryo and endosperm cells of wheat, and wheat x rye F1 hybrids, at different times after fertilization was scored by silver staining. The inactivation of rDNA of rye origin in F1 hybrids occurs simultaneously in the embryo and in the endosperm between 4 and 5 days after fertilization, when these have been through six and 10 cell cycles respectively. We conclude that the genomic interactions leading to the inactivation of the rye origin rDNA is a time-dependent process, related to the developmental stage and independent of the number of cell cycles (DNA replication rounds) they have been through.

Cell Count↗

PubMed1976

Identification of wheat (Triticum aestivum L.) chromosomes with genes controlling the level of nitrate reductase, nitrite reductase, and acid proteinase using the Chinese Spring-Hope substitution lines.

The levels of nitrate reductase, nitrite reductase, and acid proteinase were compared in the primary leaves of 8-day-old wheat seedlings of Chinese Spring, Hope, and the 21 disomic substitution lines of Hope in Chinese Spring. Two chromosomes, 7B and 7D, were considered to contain genes controlling the level of nitrate reductase. Substitution of Hope chromosome 7B caused a highly significant increase in the in vitro stability of nitrate reductase. Nitrite reductase appeared to be controlled by two major genes, located on chromosomes 4D and 7D, and two minor genes, located on chromosomes 3D and 5A. In the case of acid proteinase, substitution of chromosome 1D caused a significant reduction in enzyme activity.

Chromosome Mapping↗

PubMed2002

An update of the Courtot x Chinese Spring intervarietal molecular marker linkage map for the QTL detection of agronomic traits in wheat.

We made an update of the intervarietal molecular marker linkage map of the wheat genome developed using a doubled-haploid (DH) population derived from the cross between the cultivars "Courtot" and "Chinese Spring". This map was constructed using 187 DH lines and 659 markers. The genome was well covered (more than 95%) except for chromosomes from homoeologous group 4 and chromosomes 5D and 7D, which had gaps slightly larger than 50 cM. A core-map based on a set of 200 anchor loci (one marker each 18.4 cM) was developed. The total length of this map was 3,685 cM which is similar to the size of the international reference map of the ITMI population (3,551 cM). Map coverage was identical for the three genomes (A, B and D) and for the number of anchor loci, as well as for the size of the map. Using this map, QTLs for several agronomic traits were detected on phenotypic data from the population grown in Clermont-Ferrand (France) under natural field conditions over 6 years, and in Norwich (UK) in controlled conditions and under natural field conditions in 1 year. Almost all of the 21 chromosomes were involved in at least one trait. However, several regions seemed to contain gene clusters either for grain traits (and thus bread-making quality) or plant development traits.

Chromosome Mapping↗

PubMed2002

In-situ comparative mapping (ISCM) of Glu-1 loci in Triticum and Hordeum.

The ability to detect small low- or single-copy DNA sequences by fluorescence in-situ hybridization (FISH) is an important step towards physical mapping of plant genomes. In this study, the FISH technique was used to physically map the Glu-1 loci controlling high-molecular weight (HMW) glutenin in common wheat (Triticum aestivum cv. 'Chinese Spring') and tritordeum (an amphiploid between T. turgidum cv. durum and Hordeum chilense). The probe used was the single-copy Glu-D1-1d gene coding the 1Dx5 HMW glutenin subunit. Three loci were mapped on chromosomes of wheat homoeologous group 1 (arm 1AL, 1BL and 1DL). The Glu-1 loci were mapped (fraction of the distance from the centromere) at positions 0.76 +/- 0.01, 0.69 +/- 0.01 and 0.76 +/- 0.01, on arms 1AL, 1BL and 1DL, respectively. The Glu-1 loci were also mapped on chromosomes of homoeologous group 1 of tritordeum at positions 0.75 +/- 0.01, 0.70 +/- 0.01 and 0.60 +/- 0.01, on arms 1AL, 1BL and 1HchL, respectively. Chromosomes with positive signals were identified by reprobing chromosome preparations using both the GAA-satellite and pAs1 sequences simultaneously. The application of the FISH technique to study homoeology among different genomes is discussed.

Chromosome Mapping↗

PubMed2002

Effect of greenbugs (Homoptera: Aphididae) on yield loss of winter wheat.

The effect of greenbug, Schizaphis graminum (Rondani), feeding on the yield of four winter wheat cultivars commonly grown in Oklahoma was studied. Cultivars tested were 'Karl', a recent derivative 'Karl-92', and '2163', all greenbug-susceptible cultivars; and 'TAM-110', a cultivar with resistance to biotype E greenbugs. The objectives were to determine the effect of different greenbug densities during fall and spring on yield of winter wheat, and to develop mathematical models to quantify the effect of greenbugs on yield loss. The intensity of greenbug infestations achieved in plots by artificial infestation varied among years and growing seasons within a year, but was generally sufficient to cause a reduction in yield. Among yield components, the number of heads per square meter and the number of seeds per head were frequently negatively correlated with the accumulated number of greenbug-days per tiller. Seed weight was rarely affected by greenbug infestation. A regression model estimated yield loss for greenbug-susceptible cultivars at 0.51 kg/ha loss of yield per greenbug-day in years with near normal precipitation, and a loss of 1.17 kg/ha under severe drought conditions. The susceptible winter wheat cultivars exhibited similar yield loss in relation to the intensity of greenbug infestation, as indicated by a common slope parameter in the regression model. Results suggest that the model is robust for predicting yield loss for susceptible cultivars.

Animals↗

PubMed2000

Chromosomal location of AFLP markers in common wheat utilizing nulli-tetrasomic stocks.

Amplified fragment length polymorphism (AFLP) markers with a total of 256 EcoRI + ANN - MseI + CNN primer combinations were investigated employing the common wheat cultivar Triticum aestivum 'Chinese Spring.' On average, 103 fragments per primer combination were amplified, ranging from a maximum of 226 fragments to a minimum of 18 fragments. The primer combinations E + AAA - M + CNN and E + ATT - M + CNN produced very few distinct fragments. By using 15 randomly chosen EcoRI + ANN - MseI + CNN primer combinations, 928 AFLP markers were allocated to wheat chromosomes, of which 131 were assigned to specific chromosome arms. These AFLP markers were locus-specific and randomly distributed on the different chromosomes. In addition, 6 and 41 AFLP markers were simultaneously absent in two nulli-tetrasomics (NTs) of both homoeologous and non-homoeologous groups, respectively, whereas additional fragments were detected in N1BT1A, N5AT5D, and N6BT6A lines.

Chromosome Mapping↗

PubMed2003

Characterization of a gene from chromosome 1B encoding the large subunit of ADPglucose pyrophosphorylase from wheat: evolutionary divergence and differential expression of Agp2 genes between leaves and developing endosperm.

A full-length genomic clone containing the gene encoding the large subunit of the ADPglucose pyrophosphorylase (Agp2), was isolated from a genomic library prepared from etiolated shoots of hexaploid wheat (Triticum aestivum L., cv, Chinese Spring). The coding region of this gene is identical to one of the cDNA clones previously isolated from a developing wheat grain cDNA library and is therefore an actively transcribed gene. The sequence represented by the cDNA spans 4.8 kb of the genomic clone and contains 15 introns. 2852 bp of DNA flanking the transcription start site of the gene was cloned upstream of the GUS (beta-glucuronidase) reporter gene. This Agp2::GUS construct and promoter deletions were used to study the pattern of reporter gene expression in both transgenic tobacco and wheat plants. Histochemical analysis of GUS expression in transgenic tobacco demonstrated that the reporter gene was expressed in guard cells of leaves and throughout the seed. In transgenic wheat, reporter gene expression was confined to the endosperm and aleurone with no expression in leaves. The cloned Agp2 gene was located to chromosome 1B by gene-specific PCR with nullisomic-tetrasomic lines. Northern analysis demonstrated that the Agp2 genes are differentially expressed in leaves and developing endosperm; while all three classes of Agp2 genes are transcribed in developing wheat grain endosperm, only one is transcribed in leaves. The differences between the Agp2 genes are discussed in relation to the evolution of hexaploid wheat.

Journal Article↗

PubMed2001

Characterization of two thioredoxins h with predominant localization in the nucleus of aleurone and scutellum cells of germinating wheat seeds.

Two full-length cDNA clones, designated TrxhA and TrxhB, encoding different but very similar thioredoxin h polypeptides were isolated from wheat (Triticum aestivum cv. Chinese Spring) aleurone cells. The deduced proteins show a high similarity to each other and to thioredoxin h from other sources, in particular from T. aestivum and T. durum. One of them, TRXhA, was expressed in E. coli as a His-tagged polypeptide and used to raise polyclonal antibodies by immunization of rabbits. These antibodies identified a single band (ca. 13.5 kDa) in western blot analysis of protein extracts from all wheat organs analyzed. TRXhA and TRXhB when expressed in E. coli as intact polypetides showed indistinguishable electrophoretic mobility, which corresponded to the 13.5 kDa polypeptide detected in wheat protein extracts. The amount of thioredoxin h transcripts increased in scutellum and aleurone cells during germination but GA3 did not exert any stimulatory effect on thioredoxin h expression. Although northern blot analysis detected a single band, competitive RT-PCR showed that this band is due to the accumulation of both TrxhA and TrxhB mRNAs. These results suggest that the single band detected in western blots is due to the presence of at least two thioredoxin h polypeptides. Immunolocalization experiments confirmed the high content of thioredoxins h in scutellum and aleurone cells, and showed a low content in the starchy endosperm of germinating grains. Interestingly, though these proteins are evenly distributed in the cytosol, the highest levels of thioredoxins h were detected in the nucleus, both in aleurone and scutellum cells.

Abscisic Acid↗

PubMed1986

Genetic control of the mitochondrial form of superoxide dismutase in hexaploid wheat.

Extracts of mature grains of a large number of aneuploid derivatives of Triticum aestivum cv. Chinese Spring and of the members of five wheat-alien chromosome addition series were subjected to isoelectric focusing in polyacrylamide gels in order to study the genetic control of superoxide dismutase (SOD). Evidence was obtained that homologous structural genes for the mitochondrial form of SOD are located in the long arms of the homologous group 2 chromosomes of Chinese Spring and in chromosome 2R of Secale cereale cv. Imperial. The SOD gene loci located in chromosomes 2A, 2B, 2D, and 2R were designated Sod-A1, Sod-B1, Sod-D1, and Sod-R1, respectively. Chromosome-arm pairing data indicate that 2DL is not homologous to either 2AS or 2BL. The results of this study suggest, however, that 2BL is partially homologous to both 2AL and 2DL.

Aneuploidy↗

PubMed1994

Chromosome painting in plants: in situ hybridization with a DNA probe from a specific microdissected chromosome arm of common wheat.

We report here on the successful painting of a specific plant chromosome within its own genome. Isochromosomes for the long arm of chromosome 5 of the wheat B genome (5BL) were microdissected from first meiotic metaphase spreads of a monoisosomic 5BL line of the common wheat Triticum aestivum cv. Chinese Spring. The dissected isochromosomes were amplified by degenerate oligonucleotide-primed PCR in a single tube reaction. The amplified DNA was used as a complex probe mixture for fluorescent in situ hybridization on first meiotic metaphase spreads of lines carrying 5BL as a distinctive marker. Hybridization signals were observed, specifically, along the entire 5BL. In some of the cells, labeling was also detected in two bivalents, presumably those of the 5B "homoeologues" (partial homologues) found in common wheat (5A and 5D). The probe also revealed discrete domains in tapetal nuclei at interphase, further supporting the probe's high specificity. These data suggest that chromosome and homoeologous group-specific sequences are more abundant in 5BL than genome-specific sequences. Chromosome-painting probes, such as the one described here for 5BL, can facilitate the study of chromosome evolution in polyploid wheat.

Base Sequence↗

PubMed1990

Effects of corn oil and wheat brans on bile acid metabolism in rats.

High concentrations of colonic bile acids may promote tumor formation. Some studies have found that high levels of dietary fat increase fecal bile acid excretion, whereas others report no effect. Wheat bran appears to reduce fecal bile acid concentration. This study was conducted to determine the effect of different dietary fat levels and types of wheat bran on bile acid metabolism. Rats were fed diets containing either no fiber, 2% cholestyramine (CHO) or brans of hard red spring, soft white winter or durum wheat--at both a 5 or 20% fat level. Animals were fed for 7 wk, and feces were collected in the last week. Wheat bran (all types) significantly increased fecal mass approximately fourfold, and CHO significantly increased fecal mass twofold compared to the fiber-free diet. Increasing the fat level did not increase fecal bile acid excretion, nor did the addition of wheat bran. Addition of CHO, however, more than doubled it. CHO increased fecal bile acid concentration, all wheat brans decreased it and fat level had no effect. Bile acid pool size was increased slightly by fat level and cholestyramine feeding but not by wheat brans. These results indicate that fat level slightly alters bile acid metabolism but that wheat brans do not.

Animals↗

PubMed1996

Characterization of the Endoproteases Appearing during Wheat Grain Development.

The pattern of endoproteolytic activities occurring during wheat (Triticum aestivum, cultivar Chinese Spring) grain development was investigated. Total endoprotease activity, assayed in solution with azocasein as a substrate, increased during the early stages of grain development to reach a maximum at 15 d postanthesis that was maintained until the grain was mature. Endoprotease activity was also assayed in gradient polyacrylamide gels co-polymerized with gelatin. The increase in endoproteolytic activity was due to the appearance of up to 18 endoproteolytic bands that were arbitrarily classified into five groups (A, B, C, D, and E). The presence of serine, aspartic, metallo, and, to a lesser extent, thiol proteases in developing wheat grains was demonstrated by the use of class-specific protease inhibitors. The appearance of the different classes of endoproteases during seed development was subject to temporal control; serine proteases were more abundant at early stages and aspartic and metallo proteases were more abundant at later stages. At intermediate stages of development (15-20 d postanthesis), most of the endoproteases were localized in the aleurone, testa, and embryo. The content of acidic thiol proteases was low in the developing starchy endosperm.

Journal Article↗

PubMed2004

Determination and evaluation of the sequence and textural effects of the puroindoline a and puroindoline b genes in a population of synthetic hexaploid wheat.

Aegilops tauschii (2 n=2 x=14, DD) is a rich source of genetic variability for hexaploid wheat ( Triticum aestivum, 2 n=6 x=42, AABBDD) improvement. This variability can be accessed through utilizing synthetic hexaploid wheat lines, which contain genomes from Ae. tauschii and T. turgidum (2 n=4 x=28, AABB). Numerous desirable characteristics can and have been introgressed into common hexaploid wheat with this germplasm. In this work, the genetic variability in the two puroindoline genes (a and b) contained on the D genome, and the relationship that sequence polymorphisms in these genes have on endosperm texture among a population of 75 CIMMYT synthetic hexaploid accessions is described. Kernel texture was evaluated using the single kernel characterization system (SKCS). Kernel texture differed significantly ( P<or=0.0001) among the synthetic hexaploid accessions (range 2.6-40.9) and the parent types, durum or Ae. tauschii. The interaction term between parent types was also a significant effect ( P<or=0.0001). In addition to the 'wild-type' protein sequences of the puroindoline genes (those present in 'Chinese Spring' and all other soft wheats), three other translated sequences were identified in puroindoline a and two others in puroindoline b. These protein sequences were associated with significantly ( P<or=0.0001) softer endosperm textures than the wild-type protein sequences. As the softer alleles are expressed in a hexaploid background, they are immediately available to wheat breeding programs.

Agriculture↗

PubMed1994

High-resolution cytological mapping of the long arm of chromosome 5A in common wheat using a series of deletion lines induced by gametocidal (Gc) genes of Aegilops speltoides.

Gametocidal (Gc) genes of Aegilops in the background of the wheat genome lead to breakage of wheat chromosomes. The Q gene of wheat was used as a marker to select 19 deletion lines for the long arm of chromosome 5A of common wheat, Triticum aestivum cv. Chinese Spring (CS). The extents of deleted segments were cytologically estimated by the C-banding technique. The DNAs of deletion lines were hybridized with 22 DNA probes recognizing sites on the long arm of the chromosome (5AL) to determine their physical order. Based on the breeding behavior of the deletion lines, the location of a novel gene (Pv, pollen viability) affecting the viability of the male gamete was deduced. The segment translocated from 4AL to 5AL in CS was cytologically estimated to represent 13% of the total length of 5AL. Although DNA markers were almost randomly distributed along the chromosome arm, DNA markers located around the centromere and C-banded regions were obtained only rarely. Some deletion lines were highly rearranged in chromosome structure due to the effect(s) of the Gc gene. Applications of Gc genes for manipulating wheat chromosomes are discussed.

Blotting, Southern↗

PubMed1987

Purification and characterization of dihydrodipicolinate synthase from wheat suspension cultures.

Dihydrodipicolinate synthase, the first enzyme unique to lysine biosynthesis in higher plants, was purified about 5100-fold from suspension-cultured cells of wheat (Triticum aestivum var Chinese Spring). The synthase has an average molecular weight of 123,000 as determined by gel filtration and exhibited maximum activity at pH 8.0. The kinetics of the condensation reaction are compatible with a "Ping Pong" mechanism in which pyruvate reacts first with the enzyme to form a Schiff base. Pyruvate and l-aspartic-beta-semialdehyde (ASA) have respective K(m) values of 11.76 and 0.80 millimolar. Allosteric inhibition was observed with increasing concentrations of l-lysine and its structural analogs, including threo-4-hydroxy-l-lysine and S-(2-aminoethyl)-l-cysteine, with respective I(0.5) values of 51, 141, and 288 micromolar. These amino acids were competitive inhibitors with respect to ASA and noncompetitive inhibitors with respect to pyruvate. We propose that the binding site for lysine overlaps with the ASA binding site, possibly by an attachment of the common alanyl moiety. The wheat enzyme was inhibited by Zn(2+), Cd(2+), and Hg(2+) and also by sulfhydryl inhibitors, p-(hydroxymercuri)benzoic acid and p-chloromercuribenzenesulfonic acid.

Journal Article↗