Pierre Hucl

A Rapid Method for Quantifying Total Anthocyanins in Blue Aleurone and Purple Pericarp Wheats

ABSTRACT A simple, rapid method for determining total anthocyanins was developed for use in developing wheat cultivars with dark-blue grains. The method was evaluated as a screening test and for quantification of total anthocyanins in blue and purple wheats and related cereals. Wheat anthocyanins were significantly more extractable in ethanol or methanol than in water at different pH levels. A sample-to-solvent ratio of 1:8 at pH 1 and 25°C was used. Anthocyanin extracts of pigmented wheat and barley grains exhibited absorbance spectra similar to cyanidin 3-glucoside. The absorbance of anthocyanin extracts of 160 blue wheat experimental lines were significantly correlated with whole-grain Hunterlab color values. Total anthocyanins averaged 157 mg/kg in blue wheat whole meal and 104 mg/kg in purple wheat whole meal, whereas blue wheat bran contained 458 mg/kg as compared with 251 mg/kg in purple wheat bran.

Separation and Characterization of A- and B-Type Starch Granules in Wheat Endosperm

ABSTRACT Mature wheat (Triticum aestivum L.) endosperm contains two types of starch granules: large A-type and small B-type. Two methods, microsieving or centrifugal sedimentation through aqueous solutions of sucrose, maltose, or Percoll were used to separate A- and B-type starch granules. Microsieving could not completely separate the two types of starch granules, while centrifuging through maltose and sucrose solutions gave a homogenous population for B-type starch granules only. Centrifuging through two Percoll solutions (70 and 100%, v/v) produced purified populations of both the A- and B-type starch granules. Analysis of starch granule size distribution in the purified A- and B-type granule populations and in the whole-starch granule population obtained directly from wheat endosperm confirmed that the purified A- and B-type starch granule populations represented their counterparts in mature wheat endosperm. Centrifugations through two Percoll solutions were used to purify A- and B-type starch granule...

Physicochemical and structural characteristics of flours and starches from waxy and nonwaxy wheats

ABSTRACT A waxy spring wheat (Triticum aestivum L.) genotype was fractionated into flour and starch by roller and wet-milling, respectively. The resultant flour and starch were evaluated for end-use properties and compared with their counterparts from hard and soft wheats and with commercial waxy and nonwaxy corn (Zea mays L.) starches. The waxy wheat flour had exceptionally high levels of water absorption and peak viscosity compared with hard or soft wheat flour. The flour formed an intermediate-strength dough that developed rapidly and was relatively susceptible to mixing. Analysis by differential scanning calorimetry and X-ray diffractometry showed waxy wheat starch had higher gelatinization temperatures, a greater degree of crystallization, and an absence of an amylose-lipid complex compared with nonwaxy wheat. Waxy wheat and corn starches showed greater refrigeration and freeze-thaw stabilities than did nonwaxy starches as demonstrated by syneresis tests. They were also similar in pasting properties,...

A haplotype map of allohexaploid wheat reveals distinct patterns of selection on homoeologous genomes.

BackgroundBread wheat is an allopolyploid species with a large, highly repetitive genome. To investigate the impact of selection on variants distributed among homoeologous wheat genomes and to build a foundation for understanding genotype-phenotype relationships, we performed population-scale re-sequencing of a diverse panel of wheat lines.ResultsA sample of 62 diverse lines was re-sequenced using the whole exome capture and genotyping-by-sequencing approaches. We describe the allele frequency, functional significance, and chromosomal distribution of 1.57 million single nucleotide polymorphisms and 161,719 small indels. Our results suggest that duplicated homoeologous genes are under purifying selection. We find contrasting patterns of variation and inter-variant associations among wheat genomes; this, in addition to demographic factors, could be explained by differences in the effect of directional selection on duplicated homoeologs. Only a small fraction of the homoeologous regions harboring selected variants overlapped among the wheat genomes in any given wheat line. These selected regions are enriched for loci associated with agronomic traits detected in genome-wide association studies.ConclusionsEvidence suggests that directional selection in allopolyploids rarely acted on multiple parallel advantageous mutations across homoeologous regions, likely indicating that a fitness benefit could be obtained by a mutation at any one of the homoeologs. Additional advantageous variants in other homoelogs probably either contributed little benefit, or were unavailable in populations subjected to directional selection. We hypothesize that allopolyploidy may have increased the likelihood of beneficial allele recovery by broadening the set of possible selection targets.

Improved embryoid induction and green shoot regeneration from wheat anthers cultured in medium with maltose.

SummaryAnthers from spring wheat (Triticum aestivum L.) genotypes, including six F1 hybrids, were cultured in a modified liquid N6 medium containing either sucrose or maltose. In every case, use of maltose resulted in greater microspore callus induction and green shoot regeneration than culture in sucrose-containing medium. Induction in maltose medium also allowed green shoots to be recovered from crosses that showed only a poor response in other media and from two genotypes that did not respond to modified N6 medium with sucrose. Replacement of sucrose with maltose generally resulted in microspores having a more embryogenic mode of development in which distinct embryoids often formed. The most responsive genotype produced over 200 green shoots/100 anthers when cultured in medium with maltose.

Phenolic Content and Antioxidant Properties of Bran in 51 Wheat Cultivars

ABSTRACT Whole-grain-based diets have been suggested to reduce the incidence of cardiovascular disease and colon cancer. Phenolic compounds, most of which are present in the wheat bran, may be one of the factors contributing to whole-grain health benefits. We measured the free, bound, and total phenolic content and antioxidant activity in the bran of 51 wheat cultivars belonging to eight Western Canadian spring wheat market classes grown in a replicated trial at Saskatoon, Saskatchewan, Canada. The free phenolic (extracted with 80% v/v aqueous ethanol) content ranged from 854.1 ± 265.1 to 1,754.9 ± 240.3 μg/g of bran gallic acid equivalent (GAE). Saponification followed by a liquid-liquid solvent extraction released bound phenols ranging from 2,304.9 ± 483.0 to 5,386.1 ± 927.5 μg/g of bran GAE, contributing 66–82% of the total wheat bran phenolic content. Total phenolic content ranged from 3,406.4 ± 32.3 to 6,702.7 ± 19.6 μg/g of bran GAE, with the average being 5,197.2 ± 804.9 μg/g of bran GAE. Antioxida...

Transgene inheritance and silencing in hexaploid spring wheat

Abstract Inheritance and expression of the Act1D-uidA::nptII transgene cassette inserted into the genome of a spring wheat cultivar, ’Fielder’, was studied in T4 and T5 transgenic wheat lines. Southern blot and PCR analyses demonstrated that the transgene was inherited for five generations of selfed plants. The multiple integration pattern displayed in the T1 generation was maintained up to the T5 generation with no evidence of transgene rearrangement. There was no cytoplasmic effect on the inheritance of the transgene as observed by GUS histochemical assays in F1 seeds of reciprocal crosses (T4 crossed with untransformed ’Fielder’). Based on the histochemical GUS activity a clear Mendelian segregation ratio was not obtained in the F2 seeds of the crosses, although there was a tendency towards a two-locus insertion ratio. For one cross (A1//FD/A1), some of the transgenic plants produced low GUS and NPTII enzyme activities in seeds, even though Southern blot and PCR analyses indicated the presence of an intact transgene expression cassette. The transgene of these plants was methylated based on Southern blot analysis of genomic DNA restricted with methylation-sensitive enzymes. Northern blot analysis revealed that the plants with the methylated transgene did not accumulate the uidA::nptII fusion gene transcript.

Biochemical Characterization of the Wheat Waxy A Protein and Its Effect on Starch Properties

ABSTRACT Granule bound starch synthase1 (GBSS1) is a key enzyme in amylose biosynthesis and is encoded by the A, B and D GBSS1 wx loci in wheat. Wheat lines with mutations at the three GBSS1 loci have been identified. We have characterized and compared the grain starch of CDCW6 wheat line (null B and D for GBSS1) with PI235238 (null A and B for GBSS1), waxy (null A, B and D for GBSS1), and AC Reed (wild type wheat) grain starches. The grain starch of waxy, CDCW6, PI235238, and AC Reed lines contained ≈0, 12, 23, and 25% amylose (w/w), respectively. Waxy, partially waxy, and wild wheat grain starches showed significant differences in onset and peak transition temperatures as determined by differential scanning calorimetric analysis. Grain starches extracted from waxy, CDCW6, and PI235238 also had higher enthalpy of gelatinization values than did wild wheat starch. X-ray diffraction analysis revealed the highest crystallinity for starch extracted from waxy wheat, followed by CDCW6. The starch produced from ...

Genetic diversity within spelta and macha wheats based on RAPD analysis

Genetic diversity in a crop species is basic to improvement of the species and can be estimated at the molecular level. The objective of this study was to estimate genetic diversity within and between spelta and macha wheats. Random amplified polymorphic DNA (RAPD) analysis was conducted on 69 spelta and 32 macha wheat accessions. The classification of spelta and macha accessions, based on Jaccard genetic similarity coefficients for RAPD markers, was consistent with their geographic origin. The results indicated that the germplasm of macha wheat was more diverse than that of spelta wheat. In the dendrogram of macha wheat, four spelta-like accessions grouped together, separate from the remaining macha accessions, suggesting that these accessions were misclassified. In addition, accessions with identical RAPD patterns were found, indicating that these accessions were probably duplicated. Thus RAPD analysis can be used to estimate genetic diversity and identify duplicate accessions in wheat germplasm collections.

McKenzie hard red spring wheat

McKenzie hard red spring wheat is the first doubled haploid wheat ( Triticum aestivum L.) cultivar registered in Canada. Evaluation in the Central Bread Wheat Cooperative registration tests from 1994 to 1996 was relative to Neepawa, Katepwa, Roblin and AC M ajestic. McKenzie displayed high grain yield, early maturity, high test weight and high Hagberg falling number. It had resistance to the prevalent races of stem rust, leaf rust, and common bunt, and exhibited intermediate resistance to Fusarium head bligh t. McKenzie is well adapted to all areas of the Canadian prairies and eligible for all grades of Canada Western Red Spring (CWRS) wheat. Key words: