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PubMed1983

Genetic control of shikimate dehydrogenase in hexaploid wheat.

The genetics of shikimate dehydrogenase (SKDH; EC 1.1.1.25) was investigated in Triticum aestivum cv Chinese Spring (2n = 6x = 42; genomic formula ABD) using the zymogram technique. The enzyme occurs in two electrophoretically distinct forms on starch gels. The results of a study of aneuploid derivatives of Chinese Spring indicate that the SKDH isozyme of faster electrophoretic mobility is encoded by a gene, designated Skdh-A1, located in the p (= short) arm of chromosome 5A and that the products of two other genes, designated Skdh-B1 and Skdh-D1, located one each in the p arms of homoeologous chromosomes 5B and 5D, respectively, encode two isozymes of slower and coincident electrophoretic mobility. Additional evidence for this interpretation of the genetic basis of hexaploid wheat SKDH was obtained in studies of the SKDH zymogram phenotypes of various close relatives of hexaploid wheat, including T. monococcum, T. longissimum, T. tauschii, T. turgidum, and T. timopheevii.

Alcohol Oxidoreductases↗

PubMed1999

Identification of wheat and tritordeum chromosomes by genomic in situ hybridization using total Hordeum chilense DNA as probe

Total genomic Hordeum chilense DNA probe was hybridized to somatic chromosome spreads of Triticum aestivum 'Chinese Spring' and to four advanced tritordeum lines, the latter being the fertile amphiploid between H. chilense and durum wheat (2n = 6x = 42, AABBH(ch)H(ch)). The probe hybridized strongly to the B-genome chromosomes and to one or two bands on the A-genome chromosomes present in both wheat and tritordeum alloploids. Bands on chromosomes 1D, 2D, and 7D from hexaploid wheat were also detected. Genomic H. chilense DNA probe identified 16 chromosome pairs of the chromosome complement of hexaploid wheat and all A- and B-genome chromosomes present in the tritordeum amphiploids. The in situ hybridization patterns observed correspond to those previously reported in wheat by both N-banding and in situ hybridization with the GAA-satellite sequence (Pedersen and Langridge 1997), allowing the identification of these chromosomes. Variation among the tritordeum amphiploids for hybridization sites on chromosomes 2A, 4A, 6A, 7A, 4B, 5B, and 7B was observed. Despite of this polymorphism, all lines shared the general banding pattern. When used as probe, total H. chilense genomic DNA labeled the H. chilense chromosomes over their lengths allowing the identification of 14 H. chilense chromosomes present in the tritordeum amphiploids. In addition, chromosome-specific telomeric, interstial, and centromeric hybridization sites were observed. These hybridization sites coincide with N-banded regions in H. chilense allowing the identification of the individual H. chilense chromosomes in one of the amphiploid. The N-banded karyotypes of H. chilense (accessions H1 and H7) are presented.

Journal Article↗

PubMed2000

Purification and characterization of a moderately thermostable xylanase from Bacillus sp. strain SPS-0.

A Bacillus spp. strain SPS-0, isolated from a hot spring in Portugal, produced an extracellular xylanase upon growth on wheat bran arabinoxylan. The enzyme was purified to homogeneity by ammonium sulfate precipitation, anion exchange, gel filtration, and affinity chromatography. The optimum temperature and pH for activity was 75 degrees C and 6.0. Xylanase was stable up to 70 degrees C for 4 h at pH 6.0 in the presence of xylane. Xylanase was completely inhibited by the Hg(2+) ions. beta-Mercaptoethanol, dithiothreitol, and Mn(2+) stimulated the xylanase activity. The products of birchwood xylan hydrolysis were xylose, xylobiose, xylotriose, and xylotetraose. Kinetic experiments at 60 degrees C and pH 6.0 gave V(max) and K(m)values of 2420 nkat/mg and 0.7 mg/ml.

Journal Article↗

PubMed2002

Molecular cloning, characterization and mapping of a rhodanese like gene in wheat.

To isolate genes related to resistance to Erysiphe graminis (Blumeria graminis) DC. f. sp. tritici in wheat (Triticum aestivum L.), differential display analysis was conducted for mRNA extracted from seedlings of a wheat-Haynaldia villosa 6VS/6AL translocation line 92R137 that contains a powdery mildew resistance gene Pm21. A full-length cDNA sequence named TaTST (Triticum aestivum thiosulfate sulfurtransferase) homologous to the thiosulfate sulfurtransferase (rhodanese) in Datisca glomerata was isolated. Northern blot showed that the expression of TaTST was enhanced after infection with Erysiphe graminis. TaTST was mapped on the short arm of 6B chromosomes of wheat through Southern blot and GSP-PCR using Chinese Spring nullisomic/tetrasomic lines and ditelosomic lines. There is a homologue of TaTST on 6VS too.

Amino Acid Sequence↗

PubMed2005

Microsatellite mapping of a Triticum urartu Tum. derived powdery mildew resistance gene transferred to common wheat (Triticum aestivum L.).

A powdery mildew resistance gene from Triticum urartu Tum. accession UR206 was successfully transferred into hexaploid wheat (Triticum aestivum L.) through crossing and backcrossing. The F1 plants, which had 28 chromosomes and an average of 5.32 bivalents and 17.36 univalents in meiotic pollen mother cells (PMC), were obtained through embryos rescued owing to shriveling of endosperm in hybrid seed of cross Chinese Spring (CS) x UR206. Hybrid seeds were produced through backcrossing F1 with common wheat parents. The derivative lines had normal chromosome numbers and powdery mildew resistance similar to the donor UR206, indicating that the powdery mildew resistance gene originating from T. urartu accession UR206 was successfully transferred and expressed in a hexaploid wheat background. Genetic analysis indicated that a single dominant gene controlled the powdery mildew resistance at the seedling stage. To map and tag the powdery mildew resistance gene, 143 F2 individuals derived from a cross UR206 x UR203 were used to construct a linkage map. The resistant gene was mapped on the chromosome 7AL based on the mapped microsatellite makers. The map spanned 52.1 cM and the order of these microsatellite loci agreed well with the established microsatellite map of chromosome arm 7AL. The resistance gene was flanked by the microsatellite loci Xwmc273 and Xpsp3003, with the genetic distances of 2.2 cM and 3.8 cM, respectively. On the basis of the origin and chromosomal location of the gene, it was temporarily designated PmU.

Ascomycota↗

PubMed2002

Effect of individual Sumai 3 chromosomes on resistance to scab spread within spikes and deoxynivalenol accumulation within kernels in wheat.

Two sets of substitution lines were developed by crossing individual monosomic lines of Chinese Spring (recipient) with scab (Fusarium graminearum) resistant cultivar Sumai 3 (donor) and then using the monosomics as the recurrent male parent for four backcrosses (without selfing after each backcross). The disomic substitution lines were separated from selfed BC4F2 plants. Chromosome specific SSR markers were analyzed for polymorphism between Sumai 3 and Chinese Spring. Polymorphic markers were used to identify substitution lines for specific chromosomes. Based on the specific SSR markers, chromosome substitutions occurred in thirty-six lines, and six lines segregated alleles from the two parents or were homozygous for the allele from Chinese Spring. These substitution lines were used to evaluate Type II (spread within the head) and Type V (deoxynivalenol accumulation within kernels) scab resistance. The objective was to use the substitution lines to evaluate the effect of individual chromosomes of Sumai 3 on Type 11 and Type V scab resistance in the greenhouse. Significant differences in Type II scab resistance and deoxynivalenol (DON) levels among different Chinese Spring (Sumai 3) substitution lines were detected. Positive chromosome substitution effects on Type II scab resistance were found on chromosomes 2B, 3B. 6B, and 7A from Sumai 3. Chromosomes 3B and 7A also reduced DON accumulation within the kernels, while chromosomes IB, 2D, and 4D from Sumai 3 increased DON concentration. Chromosome 7A from Sumai 3 had the largest effect on resistance to scab spread and DON accumulation. Additional research is in progress on the scab resistance conferred by chromosome 7A.

Chromosomes, Plant↗

PubMed2005

[Variation of betaine and proline contents in wheat seedlings under salt stress].

Glycine betaine (GB) and proline contents of leaf and root were simultaneously determined by HPLC-ESI-MS at seedling stage in the three wheat (Triticum aestivum L.) varieties (salt tolerance from high to low), SW12, Ningchun No.4 and Chinese Spring (C.S) under 5 different salt stress levels. The GB contents among SW12, Ningchun No.4 and C.S were found outstanding difference by ANOVA (P<0.01) and consistent with salt tolerance in wheat. Proline contents were not different among 3 wheat varieties in leaf, but difference was found in the root between the Ningchun No.4 and C.S (P<0.05). The result suggested GB, as one of the materials for osmotic adjustment in plant, had the closest relationship with salt tolerance and could be used as an index of salt tolerance in wheat.

Betaine↗

PubMed1999

[Effects of A, D-genome chromosomes on photosynthetic carbonassimilation in common wheat] [In Process Citation]

Photosynthetic traits of ditelosomic lines with A, D-genome in CS (Chinese Spring) were investigated in this paper. The both arms of 4A-chromosome have the positive effects on photosynthetic rate, active photosynthetic duration(APD), chlorophyll content and mesophyll conductance. The short arms of 1A and both arms of 6D also have positive effects on photosynthetic rate and APD. But the long arms of 4D have negative effects on photosynthetic rate, APD and RuBPCase activity. The short arms of 2A, long arms of 5A, 6D and 7D negatively affect on RuBPCase content. So, 4A, 4D and some other chromosomes have shown important effects on photosynthesis in common wheat.

Journal Article↗

PubMed2003

Targeted molecular mapping of a major wheat QTL for Fusarium head blight resistance using wheat ESTs and synteny with rice.

A major QTL for resistance to Fusarium head blight (FHB) in wheat, Qfhs.ndsu-3BS, has been identified and verified by several research groups. The objective of this study was to increase the marker density in this QTL region using STS (sequence-tagged site) markers developed from wheat expressed sequence tags (ESTs) near Qfhs.ndsu-3BS. Because wheat chromosome 3BS and rice chromosome 1S are syntenous, the sequences of P1-derived artificial chromosome (PAC) and (or) bacterial artificial chromosome (BAC) clones covering the sub-distal portion of rice chromosome 1S were used as queries for a BLASTn search to identify wheat ESTs most likely near Qfhs.ndsu-3BS. Sixty-eight out of 79 STS primer pairs designed from wheat ESTs amplified PCR products from the genomic DNA of Triticum aestivum 'Chinese Spring'. Twenty-eight STS markers were localized on chromosome 3BS by aneuploid analysis. Six out of the nine STS markers that could be mapped in the T. aestivum 'Sumai 3'/T. aestivum 'Stoa' population had higher R2 and LOD values for this QTL than the most significant marker reported previously. Therefore, leveraging genome sequence information available in rice for wheat genetics is an effective strategy to develop DNA markers for Qfhs.ndsu-3BS, and this strategy may have broad applications for targeted mapping of other traits in cereal crops.

Chromosome Mapping↗

PubMed2005

TaVRT-2, a member of the StMADS-11 clade of flowering repressors, is regulated by vernalization and photoperiod in wheat.

The initiation of the reproductive phase in winter cereals is delayed during winter until favorable growth conditions resume in the spring. This delay is modulated by low temperature through the process of vernalization. The molecular and genetic bases of the interaction between environmental factors and the floral transition in these species are still unknown. However, the recent identification of the wheat (Triticum aestivum L.) TaVRT-1 gene provides an opportunity to decipher the molecular basis of the flowering-time regulation in cereals. Here, we describe the characterization of another gene, named TaVRT-2, possibly involved in the flowering pathway in wheat. Molecular and phylogenetic analyses indicate that the gene encodes a member of the MADS-box transcription factor family that belongs to a clade responsible for flowering repression in several species. Expression profiling of TaVRT-2 in near-isogenic lines and different genotypes with natural variation in their response to vernalization and photoperiod showed a strong relationship with floral transition. Its expression is up-regulated in the winter genotypes during the vegetative phase and in photoperiod-sensitive genotypes during short days, and is repressed by vernalization to a level that allows the transition to the reproductive phase. Protein-protein interaction studies revealed that TaVRT-2 interacts with proteins encoded by two important vernalization genes (TaVRT-1/VRN-1 and VRN-2) in wheat. These results support the hypothesis that TaVRT-2 is a putative repressor of the floral transition in wheat.

Amino Acid Sequence↗

PubMed1988

On the evolution of the adaptation of Lophopyrum elongatum to growth in saline environments.

Most species of the genus Lophopyrum Löve (Agropyron Geartn.) grow in saline environments and are more tolerant of saline stress than the species of the related genus Triticum L. A 56-chromosome amphiploid from the cross Triticum aestivum cv. Chinese Spring x Lophopyrum elongatum exceeded Chinese Spring in salt tolerance, measured as plant dry-matter production and seed yield in solution cultures with 250 mM NaCl. Thus, the adaptation of Lophopyrum to saline environments is expressed in the wheat genetic background. None of the disomic additions or substitutions of L. elongatum chromosomes in Chinese Spring showed a similar level of saline stress tolerance, which indicates that the trait depends on the activity of genes on more than one chromosome. Comparisons of disomic additions, double monosomic additions from half-diallel crosses among disomic additions, and disomic substitutions of L. elongatum chromosomes in Chinese Spring with Chinese Spring indicated that the enhanced salt tolerance of the amphiploid is primarily controlled by genes with minor effects on three of the seven chromosomes, 3E, 4E, and 7E, interacting in a largely additive manner. The salt tolerance of L. elongatum additionally depends on several minor nonadditive gene interactions. It is concluded that the adaptation of L. elongatum to growth in saline environments evolved by accumulation of new alleles in a number of loci, each with a relatively small effect on salt tolerance. It is further inferred that most of these new alleles were codominant to the original alleles and were able to act independently in enhancing salt tolerance.

Journal Article↗

PubMed2001

Direct measurement of sodium and potassium in the transpiration stream of salt-excluding and non-excluding varieties of wheat.

The xylem-feeding insect Philaenus spumarius was used to analyse sodium and potassium fluxes in the xylem of intact, transpiring wheat plants. Two cultivars were compared: the salt-excluding (Chinese Spring) and the non-excluding (Langdon). Chinese Spring accumulated much less sodium in its leaves than the salt-sensitive Langdon. After 7 d in 150 mol m(-3) NaCl, the sodium concentration in the leaf sap of Langdon reached over 600 mol m(-3). This was some three-fold greater than that in Chinese Spring. Similar findings have previously been reported from these cultivars. The reduced ion accumulation was specific to sodium; accumulation of K(+) was unaffected by NaCl in Chinese Spring, such that it developed a much lower leaf Na(+)/K(+) ratio than Langdon. The spittlebug, P. spumarius was used to sample xylem sap from both cultivars. This approach showed that the leaf xylem sap of Chinese Spring had much lower levels of sodium than that of Langdon. In the 150 mol m(-3) NaCl treatment, sodium levels in the leaf xylem reached only 2-3 mol m(-3) in Chinese Spring, compared with 8-10 mol m(-3) in Langdon. Transpiration rates were found to be similar in the two varieties. The lower leaf xylem content alone was thus sufficient to account for the reduced accumulation of sodium in leaves of Chinese Spring. The mechanisms by which xylem sodium might be lowered are discussed and it is concluded that sodium is probably excluded from the xylem in the root of Chinese Spring.

Animals↗

PubMed2000

Chromosomal location of powdery mildew resistance genes and cytogenetic analysis of meiosis in common wheat cultivar Meri.

Common wheat cv. Meri was crossed to a set of 21 Chinese Spring monosomic lines to characterize resistance to powdery mildew and to determine the chromosomal location of the gene(s). Monosomic F1 plants were allowed to self-pollinate and to produce F2 seeds. Seedlings of F2 and F3 plants and their parents were inoculated with isolates Ns 2 and 9 of Erysiphe graminis f. sp. tritici. Analysis of obtained data revealed that one major dominant gene conferring resistance is located on chromosome 1B of cv. Meri. The new gene is designated by symbol Pm28. On the basis of the trivalent configuration frequency (without univalent) at the 1st metaphase of meiosis it was found that two reciprocal translocations involving chromosomes 2A/5A and 5B/5D differentiate cv. Meri from cv. Chinese Spring. In the F1 monosomic hybrids, genes causing a decrease in pairing are found on chromosomes 4D and 6D, and genes enhancing pairing--on chromosomes 3A and 7B.

Chromosome Mapping↗

PubMed2000

[NO emission from winter wheat fields of rice-wheat rotation ecosystem in southeast China].

Measurements of NO emission from the winter wheat field of rice-wheat rotation ecosystem in southeast China during the whole period of wheat growth show that a higher NO emission was observed in spring than in autumn, and almost no emission in winter could be detected. Temperature was the most important factor determining the seasonal variation pattern of NO emission. Although the N fertilization might enlarge NO emission by a factor of 5-7, it could not modify the seasonal variation pattern. During the period of relatively weak plant activity, the diurnal variation pattern, with the maximum emission at 9:00-14:00, was determined by temperature. When plants luxuriated, however, the competition of NH4+ by plant uptake and by microbial nitrification led to a night-peak variation pattern, in which, the maximum diurnal emission usually occurred during 18:00 and 4:00 of next day, and the minimum at 8:00-16:00.

China↗

PubMed1989

Molecular analysis of an alcohol dehydrogenase (Adh) gene from chromosome 1 of wheat.

We have cloned and determined the nucleotide sequence of a gene encoding alcohol dehydrogenase (Adh) from Triticum aestivum cv. Millewa. Southern analysis using cv. Chinese Spring nullisomic-tetrasomic and ditelosomic lines established that the cloned gene mapped to the long arm of chromosome 1A and does not correspond to any previously identified wheat Adh locus. Southern analysis also provided evidence for triplicate copies of this Adh gene on the homoeologous group 1 chromosomes, while Northern blots indicated that the homoeologous group 1 Adh genes, like several other plant Adh genes, are transcribed under anaerobic conditions. Sequence analysis indicates that the cloned gene has a structure similar to both monocot and dicot Adh genes with an open reading frame encoding a polypeptide of 379 amino acids. Sequences important for eucaryotic gene expression such as the TATA box, polyadenylation signal, and intron splice sites were found in the expected positions. The open reading frame is interrupted by 8 introns which are in identical positions with 8 of the 9 introns in maize and pea Adh genes, suggesting that during evolution there are processes occurring that result in the loss of introns. Sequence analysis also revealed that the cloned wheat Adh gene shared extensive homology with the barley Adh3 gene not only in the coding region but also in the noncoding regions. However, this homology is discontinuous as a result of a 1.8-kbp insertion (TLM), which is present in the cloned wheat Adh gene and absent in the barley Adh3 gene. Sequence analysis of this insertion reveals features characteristic of the short terminal inverted repeat class of eucaryotic transposable elements. We have no evidence for the transposition of the TLM element. However, Southern blots reveal multiple copies of sequences related to TLM in the wheat genome and in other closely related species, suggesting that transposition may once have played an important role in the evolution of the Gramineae family.

Alcohol Dehydrogenase↗

PubMed2005

Partial sequences of nitrogen metabolism genes in hexaploid wheat.

Our objective was to partially sequence genes controlling nitrogen metabolism in wheat species in order to find sequence polymorphism that would enable their mapping. Primers were designed for nitrate reductase, nitrite reductase, glutamate dehydrogenase and glutamate synthase (GOGAT), and gene fragments were amplified on Triticum aestivum, T. durum, T. monococcum, T. speltoides and T. tauschii. We obtained more than 8 kb of gene sequences, mainly as coding regions (60%). Polymorphism was quantified by comparing two-by-two the three genomes of the hexaploid cultivar Arche and genomes of diploid wheat species. On average, the polymorphism rate was higher for non-coding regions, where it ranged from 1/60 to 1/23, than for coding regions (range: 1/110-1/40) except when the hexaploid D genome was compared to that of T. tauschii (1/800 and 1/816, respectively). Genome-specific primers were devised for the ferredoxin-dependent (Fd)-GOGAT gene, and they enabled the mapping of this gene on homoeologous chromosomes of group 2 using Chinese Spring deletion lines. A single nucleotide polymorphism (SNP) detected between the two hexaploid wheat cultivars Arche and Recital was used to genetically map Fd-GOGAT on chromosome 2D using a population of dihaploid lines. Fd-GOGAT-specific primers were used to estimate the SNP rate on a set of 11 hexaploid and nine Durum wheat genotypes leading to the estimate of 1 SNP/515 bp. We demonstrate that polymorphism detection enables heterologous, homeologous and even paralogous copies to be assigned, even if the elaboration of specific primer pairs is time-consuming and expensive because of the sequencing.

Amino Acid Oxidoreductases↗

PubMed2006

The genetics of nitrogen use in hexaploid wheat: N utilisation, development and yield.

A genetic study is presented for traits relating to nitrogen use in wheat. Quantitative trait loci (QTLs) were established for 21 traits relating to growth, yield and leaf nitrogen (N) assimilation during grain fill in hexaploid wheat (Triticum aestivum L.) using a mapping population from the cross Chinese Spring x SQ1. Glutamine synthetase (GS) isozymes and estimated locations of 126 genes were placed on the genetic map. QTLs for flag leaf GS activity, soluble protein, extract colour and fresh weight were found in similar regions implying shared control of leaf metabolism and leaf size. Flag leaf traits were negatively associated with days to anthesis both phenotypically and genetically, demonstrating the complex interactions of metabolism with development. One QTL cluster for GS activity co-localised with a GS2 gene mapped on chromosome 2A, and another with the mapped GSr gene on 4A. QTLs for GS activity were invariably co-localised with those for grain N, with increased activity associated with higher grain N, but with no or negative correlations with grain yield components. Peduncle N was positively correlated, and QTLs co-localised, with grain N and flag leaf N assimilatory traits, suggesting that stem N can be indicative of grain N status in wheat. A major QTL for ear number per plant was identified on chromosome 6B which was negatively co-localised with leaf fresh weight, peduncle N, grain N and grain yield. This locus is involved in processes defining the control of tiller number and consequently assimilate partitioning and deserves further examination.

Ammonia↗

PubMed2000

Effect of maturity on degradation kinetics of sod-seeded cereal grain forage grown in northern Arkansas.

Wheat (Triticum aestivum L.), oat (Avena sativa L.), and rye (Secale cereale L.) were overseeded into a dormant bermudagrass (Cynodon dactylon (L.) Pers.) sod and harvested at 3-wk intervals throughout March, April, May, and early June. Plant growth stage was documented for each forage on each harvest date, and harvested forages were evaluated for forage quality characteristics. Degradation kinetics of DM and NDF for these forages were evaluated by the in situ method. Fractional degradation rates for DM and NDF in all three species were relatively rapid for vegetative forage (> or =0.086 h(-1)) but declined rapidly by the heading stage of development and stabilized thereafter. Forage quality declined and forages were more resistant to ruminal degradation as plants entered the reproductive stages of growth. Based on these findings, growth stage is an effective predictor of most characteristics of in situ DM and NDF disappearance. The relationships between these degradation parameters and growth stage were typically explained with quadratic or cubic models. Clearly, forage quality characteristics of overseeded rye deteriorated more rapidly with phenological development and growth stage than quality characteristics of overseeded wheat and oat grown in the same environment. For rye, this problem is further complicated by its accelerated phenological development. These factors combine to permit a very narrow harvest window in early spring, relative to the other cereal grains evaluated. Acceptable forage quality may persist for an extended period in wheat and oat; this suggests that producers wishing to utilize these forages may lengthen the harvest window by planting more than one species, either as a mixture or preferably in independent stands.

Animal Feed↗