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PubMed2006

Updated estimates of the selenomethionine content of NIST wheat reference materials by GC-IDMS.

Updated estimates of the selenomethionine content of four NIST wheat reference materials have been obtained by use of a revised gas chromatography-stable-isotope dilution mass spectrometric method. The revised method makes use of digestion with methanesulfonic acid, which enables more complete recovery of endogenous selenomethionine than was previously achieved by overnight denaturing treatment in 0.1 mol L(-1) HCl. The NIST wheat reference materials each contain approximately 55% of their total Se content as selenomethionine. Information about forms of Se in reference materials adds value to these materials in Se speciation studies. Estimates of selenomethionine content are also provided for other wheat samples, including several grown under conditions of exposure to high Se levels. These samples also contain approximately 55% of their total Se content as selenomethionine. The consistent level of 55% of total selenium occurring in the form of selenomethionine when the total selenium content varies by a factor of 500 is suggestive of an active mechanism of incorporation of selenium into wheat grain. Figure Selenomethionine content of wheat samples.

Chemistry Techniques, Analytical↗

PubMed2005

Effects of microbial community diversity on the survival of Pseudomonas aeruginosa in the wheat rhizosphere.

Ecological theory suggests that microbial communities with greater microbial diversity would be less susceptible to invasion by potential opportunistic pathogens. We investigated whether the survival of the opportunistic pathogen Pseudomonas aeruginosa in the wheat rhizosphere would be affected by the presence of natural and constructed microbial communities of various diversity levels. Three levels of microbial community diversity were derived from wheat roots by a dilution/extinction approach. These wheat rhizosphere inocula, as well as a gnotobiotic microbial community consisting of seven culturable wheat rhizobacterial isolates, were introduced into the nutrient solution of hydroponically grown wheat plants on the day of planting. Phenotypic characterization of the culturable microbial communities on R2A medium, Shannon microbial diversity index, community-level physiological profiles, and terminal restriction fragment length polymorphisms were used to assess the varying microbial diversity levels. At day 7 the roots were invaded with P. aeruginosa and the number of P. aeruginosa colony forming units per root were measured at day 14. The average number of surviving P. aeruginosa cells was 3.52, 4.90, 7.18, 6.65 log(10) cfu/root in the high, medium, low, and gnotobiotic microbial community diversity level treatments, respectively. The invasibility of the rhizosphere communities by P. aeruginosa was inversely related to the level of diversity from the dilution extinction gradient. The gnotobiotic community did not confer protection against P. aeruginosa invasion. Although these data indicate that invasibility is inversely related to diversity, further study is needed to both reproduce these findings and define the specific mechanisms of the diversity effect.

Biodiversity↗

PubMed1996

The single-batch bioconversion of wheat straw to ethanol employing the fungus Trichoderma viride and the yeast Pachysolen tannophylus.

We have developed and optimized a single-batch process of the production of ethanol from wheat straw employing the fungus Trichoderma viride and the yeast Pachysolen tannophylus. T. viride and Aspergillus niger were examined for their ability to produce fermentable sugars from cellulosic waste materials, e.g. different kinds of straw and wood waste. T. viride most efficiently saccharified delignified wheat straw within 3 days at 25-30 degrees C with a yield of reducing sugars of 27 g from 50 g delignified wheat straw. The resulting wheat straw hydrolysates contained xylose and glucose in a 1:1.6 molar ratio. After heat inactivation of fungal activities the sugars were converted to ethanol by the oxygen-tolerant yeast P. tannophylus in the same batch. Under the optimized conditions developed (all weights are per liter) 70 g natural untreated wheat straw (100%) yielded 50 g delignified straw (71.4%), which was saccharified to 27 g reducing sugars (38.6%). Fermentation of the sugars yielded 11.8 g ethanol (16.9%) and followed the molar equation: 1 xylose + 1.6 glucose --> 5.3 ethanol + 5.6 CO2.

Aspergillus niger↗

PubMed1999

Photoperiod-sensitive cytoplasmic male sterility in wheat: nuclear-mitochondrial incompatibility results in differential processing of the mitochondrial orf25 gene.

An alloplasmic wheat line with the cytoplasm of Aegilops crassa expresses photoperiod-sensitive cytoplasmic male sterility (PCMS). Southern- and Northern-hybridization analyses showed that this line contains alterations in both the gene structure and transcription patterns of the mitochondrial gene orf25. In this study, the nucleotide sequence around the orf25 gene of Ae. crassa (CR-orf25) and common wheat (AE-orf25) was determined, and we found that the upstream region of CR-orf25 had been replaced by that of rps7 of common wheat (AE-rps7) through recombination. A novel open reading frame (orf48) is present upstream of CR-orf25. In these three genes, transcription was initiated from the consensus promoter motif of plant mitochondrial genes located in the upstream regions. Processing enzymes in Ae. crassa and common wheat cleave the respective precursor mRNAs, namely CR-orf25 and AE-rps7, at sites similar to that of the premature mitochondrial 26S rRNA. In contrast, the precursor mRNA is not effectively processed at the target sequence of CR-orf25 in the alloplasmic wheat line. Because major transcripts of the euplasmic CR-orf25 and AE-rps7 genes would result in a truncated orf48 product, one possibility is that the orf48 protein might disturb mitochondrial function at a specific stage and hence affect the expression of the PCMS trait.

Amino Acid Sequence↗

PubMed2006

Targeted expression of redesigned and codon optimised synthetic gene leads to recrystallisation inhibition and reduced electrolyte leakage in spring wheat at sub-zero temperatures.

Antifreeze proteins (AFPs) adsorb to ice crystals and inhibit their growth, leading to non-colligative freezing point depression. Crops like spring wheat, that are highly susceptible to frost damage, can potentially be made frost tolerant by expressing AFPs in the cytoplasm and apoplast where ice recrystallisation leads to cellular damage. The protein sequence for HPLC-6 alpha-helical antifreeze protein from winter flounder was rationally redesigned after removing the prosequences in the native protein. Wheat nuclear gene preferred amino acid codons were used to synthesize a recombinant antifreeze gene, rAFPI. Antifreeze protein was targeted to the apoplast using a Murine leader peptide sequence from the mAb24 light chain or retained in the endoplasmic reticulum using C-terminus KDEL sequence. The coding sequences were placed downstream of the rice Actin promoter and Actin-1 intron and upstream of the nopaline synthase terminator in the plant expression vectors. Transgenic wheat lines were generated through micro projectile bombardment of immature embryos of spring wheat cultivar Seri 82. Levels of antifreeze protein in the transgenic lines without any targeting peptide were low (0.06-0.07%). The apoplast-targeted protein reached a level of 1.61% of total soluble protein, 90% of which was present in the apoplast. ER-retained protein accumulated in the cells at levels up to 0.65% of total soluble proteins. Transgenic wheat line T-8 with apoplast-targeted antifreeze protein exhibited the highest levels of antifreeze activity and provided significant freezing protection even at temperatures as low as -7 degrees C.

Animals↗

PubMed2025

Replacement of chromosome 3D with Thinopyrum chromosome 3St led to increased drought tolerance during the flowering stage in wheat.

The stable 3St(3D) substitution line offers promising genetic potential for improving drought tolerance in wheat during critical reproductive stages. The flowering stage is highly susceptible to drought, which significantly reduces wheat grain yield globally. Low genetic diversity in wheat further limits the discovery of optimal gene variants for breeding climate-resilient varieties. The substitution of chromosome 3D by a group 3 chromosome pair from Thinopyrum intermedium × Th. ponticum artificial hybrid was identified using in situ hybridization and genotyping-by-sequencing. This homoeologous substitution showed good functional compensation for grain yield and fertility, similar to the wheat parents ('Mv9kr1' and 'Mv Karizma') in field and greenhouse trials. The substitution line exhibits a semidwarf phenotype due to the Rht8 and Rht2 dwarfing alleles. Automated shoot phenotyping after a 10-day water withdrawal at flowering revealed efficient water preservation allowing to maintain photosynthetic functions, sustained photosynthetic activity, and less chlorophyll degradation, indicated by Normalized Difference Vegetation Index (NDVI) and modified Normalized Difference Index (mND705) values and moderate level of protective functions shown by the expression of stress-related genes. Compared to the wheat parents, the substitution line developed thicker roots with increased volume under drought, resulting in a lower surface-to-volume ratio. This may enhance water storage efficiency and help reduce yield loss under drought conditions.

Triticum↗

PubMed2005

Fructan:fructan 1-fructosyltransferase, a key enzyme for biosynthesis of graminan oligomers in hardened wheat.

Fructans play important roles not only as a carbon source for survival under persistent snow cover but also as agents that protect against various stresses in overwintering plants. Complex fructans having both beta-(2,1)- and beta-(2,6)-linked fructosyl units accumulate in wheat (Triticum aestivum L.) during cold hardening. We detected fructan: fructan 1-fructosyltransferase (1-FFT; EC 2.4.1.100) activity for catalyzing the formation and extension of beta-(2,1)-linked fructans in hardened wheat tissues, cloned cDNAs (wft3 and wft4) of 1-FFT, and analyzed the enzymatic properties of a wft3 recombinant protein (Wft3m) produced by yeast. Wft3m transferred beta-(2,1)-linked fructosyl units to phlein, an extension of sucrose through beta-(2,6)-linked fructosyl units, as well as to inulin, an extension of sucrose through beta-(2,1)-linked fructosyl units, but could not efficiently synthesize long inulin oligomers. Incubation of a mixture of Wft3m and another recombinant protein of wheat, sucrose:fructan 6-fructosyltransferase (6-SFT), with sucrose and 1-kestotriose produced fructans similar to those that accumulated in hardened wheat tissues. The results demonstrate that 1-FFT produces branches of beta-(2,1)-linked fructosyl units to phlein and graminan oligomers synthesized by 6-SFT and contributes to accumulation of fructans containing beta-(2,1)- and beta-(2,6)-linked fructosyl units. In combination with sucrose:sucrose 1-fructosyltransferase (1-SST; EC 2.4.1.99) and 6-SFT, 1-FFT is necessary for fructan synthesis in hardened wheat.

Amino Acid Sequence↗

PubMed2005

Structural analysis of wheat wax (Triticum aestivum, c.v. 'Naturastar' L.): from the molecular level to three dimensional crystals.

In order to elucidate the self assembly process of plant epicuticular waxes, and the molecular arrangement within the crystals, re-crystallisation of wax platelets was studied on biological and non-biological surfaces. Wax platelets were extracted from the leaf blades of wheat (Triticum aestivum L., c.v. 'Naturastar', Poaceae). Waxes were analysed by gas chromatography (GC) and mass spectrometry (MS). Octacosan-1-ol was found to be the most abundant chemical component of the wax mixture (66 m%) and also the determining compound for the shape of the wax platelets. The electron diffraction pattern showed that both the wax mixture and pure octacosan-1-ol are crystalline. The re-crystallisation of the natural wax mixture and the pure octacosan-1-ol were studied by scanning tunnelling microscopy (STM), atomic force microscopy (AFM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Crystallisation of wheat waxes and pure octacosano-1-ol on the non polar highly ordered pyrolytic graphite (HOPG) led to the formation of platelet structures similar to those found on the plant surface. In contrast, irregular wax morphologies and flat lying plates were formed on glass, silicon, salt crystals (NaCl) and mica surfaces. Movement of wheat wax through isolated Convallaria majalis cuticles led to typical wax platelets of wheat, arranged in the complex patterns typical for C. majalis. STM of pure octacosan-1-ol monolayers on HOPG showed that the arrangement of the molecules strictly followed the hexagonal structure of the substrate crystal. Re-crystallisation of wheat waxes on non-polar crystalline HOPG substrate showed that technical surfaces could be used to generate microstructured, biomimetic surfaces. AFM and SEM studies proved that a template effect of the substrate determined the orientation of the re-grown crystals. These effects of the structure and polarity of the substrate on the morphology of the epicuticular waxes are relevant for understanding interactions between biological as well as technical surfaces and waxes.

Crystallization↗

PubMed2006

Cytotoxic thio-malate is transported by both an aluminum-responsive malate efflux pathway in wheat and the MAE1 malate permease in Schizosaccharomyces pombe.

Aluminum (Al) tolerance in wheat (Triticum aestivum L.) is mainly achieved by malate efflux, which is regulated by the expression of the recently identified gene, presumably encoding an Al-activated malate efflux transporter (ALMT1). However, the transport mechanism is not fully understood, partly as a result of the rapid turnover of its substrate. We developed a tool to study malate transport in wheat by screening biological compounds using the well-characterized Schizosaccharomyces pombe malate transporter (SpMAE1). Expression of SpMAE1 in both S. pombe and Saccharomyces cerevisiae, which has no SpMAE1 homologue, caused hypersensitivity to thio-malic acid. This hypersensitivity was prominent at pH 3.5, but not pH 4.5, and was accompanied by an increase in thiol content, indicating that SpMAE1 mediates the uptake of thio-malic acid at a specific low pH. In wheat, root apices were able to accumulate thio-malic acid without growth reduction at pH values above 4.2. Pretreatment of root apices with thio-malic acid followed by Al treatment induced thio-malate efflux. Al-induced thio-malate efflux was much higher in Al-resistant cultivars/genotypes than in Al-sensitive ones, and was accompanied by a decrease in thiol-content. Thio-malate efflux in the Al-resistant cultivar was slightly activated by lanthanum or ytterbium ion. Thio-malic acid did not alleviate the Al-induced inhibition of root elongation in wheat. Taken together, our results suggest that thio-malate acts as an analogue for malate in malate transport systems in wheat and yeast, and that it may be a useful tool for the analysis of malate transport involved in Al-tolerance and of other organic ion transport processes.

Aluminum↗

PubMed2005

Isolation and characterization of 18 genes encoding alpha- and beta-expansins in wheat (Triticum aestivum L.).

Expansins are thought to be key regulators of cell wall extension during plant growth. In this study, we isolated 18 expansin genes from wheat, nine of which encode alpha-expansins while the other nine code for beta-expansins. The cysteine-rich and tryptophan-rich regions of the deduced amino acid sequences of all 18 expansins were highly conserved. Genomic sequences were obtained for 17 of the genes, and their intron patterns were determined. Four (A, C, D, E) of the six intron positions known in expansin genes from other species were found to be occupied in these wheat expansin genes. Five wheat expansin genes were mapped to chromosomes 1L, 2L, 5L and 6L respectively, by in silico and comparative mapping. The 18 wheat expansin genes were expressed in leaf, root and the developing seed. Moreover, it was demonstrated that four beta-expansin genes were up-regulated in the internode tissue in F1 hybrids, suggesting that changes in the regulation of these genes in hybrid might contribute to the heterosis observed in internode length and plant height. We therefore conclude that expansins are encoded by a multigene family in wheat, and could play important roles in growth and development.

Amino Acid Sequence↗

PubMed2005

A candidate autonomous version of the wheat MITE Hikkoshi is present in the rice genome.

A miniature inverted-repeat transposable element (MITE), designated as Hikkoshi, was previously identified in the null Wx-A1 allele of Turkish bread wheat lines. This MITE is 165 bp in size and has 12-bp terminal inverted repeats (TIRs) flanked by 8-bp target site duplications (TSDs). Southern and PCR analyses demonstrated the presence of multiple copies of Hikkoshi in the wheat genome. Database searches indicated that Hikkoshi MITEs are also present in barley, rice and maize. A 3.4-kb element that has Hikkoshi-like TIRs flanked by 8-bp TSDs has now been identified in the rice genome. This element shows high similarity to the 5' subterminal region of the wheat Hikkoshi MITE and contains a transposase (TPase) coding region. The TPase has two conserved domains, ZnF_TTF and hATC, and its amino acid sequence shows a high degree of homology to TPases encoded by Tip100 transposable elements belonging to the hAT superfamily. We designated the 3.4-kb element as OsHikkoshi. Several wheat clones deposited in EST databases showed sequence similarity to the TPase ORF of OsHikkoshi. The sequence information from the TPase of OsHikkoshi will thus be useful in isolating the autonomous element of the Hikkoshi system from wheat.

Alleles↗

PubMed2006

Putative fasciclin-like arabinogalactan-proteins (FLA) in wheat (Triticum aestivum) and rice (Oryza sativa): identification and bioinformatic analyses.

Putative plant adhesion molecules include arabinogalactan-proteins having fasciclin-like domains. In animal, fasciclin proteins participate in cell adhesion and communication. However, the molecular basis of interactions in plants is still unknown and none of these domains have been characterized in cereals. This work reports the characterization of 34 wheat (Triticum aestivum) and 24 rice (Oryza sativa) Fasciclin-Like Arabinogalactan-proteins (FLAs). Bioinformatics analyses show that cereal FLAs share structural characteristics with known Arabidopsis FLAs including arabinogalactan-protein and fasciclin conserved domains. At least 70% of the wheat and rice FLAs are predicted to be glycosylphosphatidylinositol-anchored to the plasma membranes. Expression analyses determined from the relative abundance of ESTs in the publicly available wheat EST databases and from RNA gel blots indicate that most of these genes are weakly expressed and found mainly in seeds and roots. Furthermore, most wheat genes were down regulated by abiotic stresses except for TaFLA9 and 12 where cold treatment induces their expression in roots. Plant fasciclin-like domains were predicted to have 3-D homology with FAS1 domain of the fasciclin I insect neural cell adhesion molecule with an estimated precision above 70%. The structural analysis shows that negatively charged amino acids are concentrated along the beta1-alpha3-alpha4-beta2 edges, while the positively charged amino acids are concentrated on the back side of the folds. This highly charged surface distribution could provide a way of mediating protein-protein interactions via electrostatic forces similar to many other adhesion molecules. The identification of wheat FLAs will facilitate studying their function in plant growth and development and their role in stress response.

Amino Acid Sequence↗

PubMed2000

Two loci on wheat chromosome 5A regulate the differential cold-dependent expression of the cor14b gene in frost-tolerant and frost-sensitive genotypes.

Although cold acclimation in cereals involves the expression of many cold-regulated genes, genetic studies have shown that only very few chromosomal regions carry loci that play an important role in frost tolerance. To investigate the genetic relationship between frost tolerance and the expression of cold-regulated genes, the expression and regulation of the wheat homolog of the barley cold-regulated gene cor14b was studied at various temperatures in frost-sensitive and frost-tolerant wheat genotypes. At 18/15 degrees C (day/night temperatures) frost-tolerant plants accumulated cor14b mRNAs and expressed COR14b proteins, whereas the sensitive plants did not. This result indicates that the threshold temperature for induction of the wheat cor14b homolog is higher in frost-resistant plants, and allowed us to use this polymorphism in a mapping approach. Studies made with chromosome substitution lines showed that the polymorphism for the threshold induction temperature of the wheat cor14b homolog is controlled by a locus(i) located on chromosome 5A of wheat, while the cor14b gene was mapped in Triticum monococcum on the long arm of chromosome 2Am. The analysis of single chromosome recombinant lines derived from a cross between Chinese Spring/Triticum spelta 5A and Chinese Spring/Cheyenne 5A identified two loci with additive effects that are involved in the genetic control of cor14b mRNA accumulation. The first locus was tightly linked to the marker psr911, while the second one was located between the marker Xpsr2021 and Frost resistance 1 (Fr1).

Blotting, Northern↗

PubMed2000

RFLP-based analysis of three RbcS subfamilies in diploid and polyploid species of wheat.

The RbcS multigene family of hexaploid (bread) wheat, Triticum aestivum (genome BBAADD), which encodes the small subunit of Rubisco, comprises at least 22 genes. Based on their 3' non-coding sequences, these genes have been classified into four subfamilies (SFs), of which three (SF-2, SF-3 and SF-4) are located on chromosomes of homoeologous group 2 and one (SF-1) on homoeologous group 5. In the present study we hybridized three RbcS subfamily-specific probes (for SF-1, SF-2 and SF-3) to total DNA digested with four restriction enzymes and analyzed the RFLP patterns of these subfamilies in eight diploid species of Aegilops and Triticum, and in two tetraploid and one hexaploid species of wheat (the diploid species are the putative progenitors of the polyploid wheats). The three subfamilies varied in their level of polymorphism, with SF-2 being the most polymorphic in all species. In the diploids, the order of polymorphism was SF-2 > SF-3 > SF-1, and in the polyploids SF-2 > SF-1 > SF-3. The RbcS genes of the conserved SF-1 were previously reported to have the highest expression levels in all the wheat tissues studied, indicating a negative correlation between polymorphism and gene expression. Among the diploids, the species with the D and the S genomes were the most polymorphic and the A-genome species were the least polymorphic. The polyploids were less polymorphic than the diploids. Within the polyploids, the A genome was somewhat more polymorphic than the B genome, while the D genome was the most conserved. Among the diploid species with the A genome, the RFLP pattern of T. urartu was closer to that of the A genome of the common wheat cultivar Chinese Spring (CS) than to that of T. monococcum. The pattern in Ae. tauschii was similar to that of the D genome of CS. Only partial resemblance was found between the RFLP patterns of the species with the S genome and the B genome of CS.

Chromosome Mapping↗

PubMed2005

Targeted mapping of ESTs linked to the adult plant resistance gene Lr46 in wheat using synteny with rice.

The gene Lr46 has provided slow-rusting resistance to leaf rust caused by Puccinia triticina in wheat (Triticum aestivum), which has remained durable for almost 30 years. Using linked markers and wheat deletion stocks, we located Lr46 in the deletion bin 1BL (0.84-0.89) comprising 5% of the 1BL arm. The distal part of chromosome 1BL of wheat is syntenic to chromosome 5L of rice. Wheat expressed sequence tags (ESTs) mapping in the terminal 15% of chromosome 1BL with significant homology to sequences from the terminal region of chromosome 5L of rice were chosen for sequence-tagged site (STS) primer design and were mapped physically and genetically. In addition, sequences from two rice bacterial artificial chromosome clones covering the targeted syntenic region were used to identify additional linked wheat ESTs. Fourteen new markers potentially linked to Lr46 were developed; eight were mapped in a segregating population. Markers flanking (2.2 cM proximal and 2.2 cM distal) and cosegregating with Lr46 were identified. The physical location of Lr46 was narrowed to a submicroscopic region between the breakpoints of deletion lines 1BL-13 [fraction length (FL)=0.89-1] and 1BL-10 (FL=0.89-3). We are now developing a high-resolution mapping population for the positional cloning of Lr46.

Basidiomycota↗

PubMed2005

Alteration of the embryo transcriptome of hexaploid winter wheat (Triticum aestivum cv. Mercia) during maturation and germination.

Grain dormancy and germination are areas of biology that are of considerable interest to the cereal community. We have used a 9,155-feature wheat unigene cDNA microarray resource to investigate changes in the wheat embryo transcriptome during late grain development and maturation and during the first 48 h of postimbibition germination. In the embryo 392 mRNAs accumulated by twofold or greater over the time course from 21 days postanthesis (dpa) to 40 dpa and on through 1 and 2 days postgermination. These included mRNAs encoding proteins involved in amino acid biosynthesis and metabolism, cell division and subsequent cell development, signal transduction, lipid metabolism, energy production, protein turnover, respiration, initiation of transcription, initiation of translation and ribosomal composition. A number of mRNAs encoding proteins of unknown function also accumulated over the time course. Conversely 163 sequences showed decreases of twofold or greater over the time course. A small number of mRNAs also showed rapid accumulation specifically during the first 48 h of germination. We also examined alterations in the accumulation of transcripts encoding proteins involved in abscisic acid signalling. Thus, we describe changes in the level of transcripts encoding wheat Viviparous 1 (Vp1) and other interacting proteins. Interestingly, the transcript encoding wheat Viviparous-interacting protein 1 showed a pattern of accumulation that correlates inversely with germination. Our data suggests that the majority of the transcripts required for germination accumulate in the embryo prior to germination and we discuss the implications of these findings with regard to manipulation of germination in wheat.

Computational Biology↗

PubMed2005

Genetic and in silico comparative mapping of the polyphenol oxidase gene in bread wheat (Triticum aestivum L.).

Polyphenol oxidases (PPOs) are involved in the time-dependent darkening and discolouration of Asian noodles and other wheat end products. In this study, a doubled haploid (DH) population derived from Chara (moderately high PPO activity)/WW2449 (low PPO activity) was screened for PPO activity based on L-DOPA and L-tyrosine assays using whole seeds. Both these assays were significantly genetically correlated (r = 0.91) in measuring the PPO activity in this DH population. Quantitative trait loci (QTLs) analysis utilising a skeleton map enabled us to identify a major QTL controlling PPO activity based on L-DOPA and L-tyrosine on the long arm of chromosome 2A. The simple sequence repeat (SSR) marker GWM294b explained over 82% of the line mean phenotypic variation from samples collected in both 2000 and 2003. Four SSR markers were validated for PPO linkage in genetically diverse backgrounds and proven to correctly predict the PPO activity in more than 92% of wheat lines. Physical mapping using deletion lines of Chinese Spring has confirmed the location of the GWM294b, GWM312 and WMC170 on chromosome 2AL, between deletion breakpoints 2AL-C to 0.85. In order to identify functional gene markers, data searches for alignments between rice BAC/PAC clones assembled on chromosome 1 and 4, chromosome 7, and (1) the wheat expressed sequence tags mapped in deletion bin (2AL-C to 0.85) and (2) the coding sequence of a previously cloned wheat PPO gene were made and found significant sequence similarities with the PPO gene or common central domain of tyrosinase. Available PPO gene sequences in the National Centre for Biotechnology Information (NCBI) database have revealed that there is a significant molecular diversity at the nucleotide and amino acid level in the wheat PPO genes.

Alleles↗

PubMed2005

Molecular cytogenetic characterization and seed storage protein analysis of 1A/1D translocation lines of durum wheat.

Two durum wheat [Triticum turgidum L. ssp. durum (Desf.) Husn.] lines carrying the high-molecular-weight (HMW) glutenin subunits (GS) 1 D x 5 + 1Dy10 encoded by Glu-D1d, L252 and S99B34, were characterized using fluorescent genomic in-situ hybridization (FGISH) and microsatellite markers. These two durum lines were derived from the crosses in which the common wheat (T. aestivum L.) 'Len' and durum wheat 'Langdon' (LDN) and 'Renville' were involved. FGISH patterns of the mitotic chromosomes indicated that these two durum lines have one pair of 1AS.1AL-1DL translocated chromosomes in which the terminal region of 1AL was replaced by a homoeologous segment of 1DL. The 1DL segment spans approximately 31% of the long arm of the translocated chromosome. Microsatellite marker analysis confirmed the 1AS.1AL-1DL translocation and determined the translocation breakpoint to be distal to Xgwm357 on 1AL. Seed storage proteins (GS and gliadins) were analysed in these two 1AS.1AL-1DL translocation lines and three sib lines (L092, S99B19 and S99B33) using SDS-PAGE and A-PAGE. The SDS-PAGE and A-PAGE profiles demonstrated that the two low yielding lines (L252 and S99B19) had the low-molecular-weight (LMW) -1 GS encoded by Glu-A3k and Glu-B3s and 1B-encoded gliadins from LDN, and the other three lines (L092, S99B33 and S99B34) with higher yield had LMW-2 GS and 1B-encoded gliadins from Renville, suggesting that undesirable genetic components from LDN might limit substantial improvement of yield. Thus, the translocation lines with 1 D x 5 + 1Dy10 and LMW-2, which are associated with good bread-making and pasta qualities, respectively, in a good genetic background will be useful for developing durum cultivars with dual-purpose end-use. Results from this study demonstrate that the D-genome could play an important role in the genetic improvement of durum wheat and evolution of the A- and B-genomes in tetraploid wheat.

Genetic Markers↗