Durum-type wheat with high bread-making quality.

A durum-type wheat (2n = 4x = 28) with high bread-making quality was produced by crossing a durum-wheat variety with a common bread-wheat variety (2n = 6x = 42), backcrossing to the bread-wheat variety for three generations, and then selecting for 28-chromosome plants. The high quality is tentatively attributed to a translocation involving one of the D-genome chromosomes.

[Wheat: effects of mixing in breadmaking]. / Trigo: effectos del mezclado en panificación.

The purpose of this work was to investigate the effects of mixing especially of unmixing, in the breadmaking process. The three wheat cultivars selected for the study were Glenlea, Neepawa and Fredrick. To increase the mixing strength of Fredrick, a blend of equal parts of Fredrick and Neepawa flours (Fr/Np, 50/50) was prepared. The wheat doughs under study required widely different times and energy inputs for mixing. Glenlea, Neepawa and Fr/Np needed 14.3, 3.0 and 2.8 Wh/kg of dough, respectively, to reach the first development peak. The unmixed doughs showed a marked deterioration of bread quality in relation to those mixed to the first development peak. Increases of unmixing times produced remarkable decreases of bread quality. At 16 min of unmixing the reduction of loaf volume, in relation to the optimum development stage, ranged from 34 to 62%. After unmixing, remixing the dough to a second development peak caused a high improvement in the quality of the final product. The breadmaking tests demonstrated that the unmixing effects were stronger for the stronger flours.

Cytological characterization, powdery mildew resistance and storage protein composition of tetraploid and hexaploid 1BL/1RS wheat-rye translocation lines.

Progenies of a tetraploid 1BL/1RS wheat-rye translocation line, CV 256, selected from the cross 'Cando' x 'Veery', were analyzed by means of Giemsa C-banding. CV 256 is cytologically stable for the presence of the 1BL/1RS translocation but still segregating for A- and B-genome chromosomes of 'Cando' and 'Veery'. In CV 256, nucleolar activity of the 1RS NOR locus is suppressed, as judged by the absence of a secondary constriction in that rye segment and the capability of organizing nucleoli. PAGE analysis of prolamins confirmed the presence of two 1RS secalins in all single seeds analyzed. SDS-PAGE analysis of reduced glutenins of single seeds indicated that some seeds contained the 'Cando' Glu-B1 locus (subunits 6+8), some contained the 'Veery' Glu-B1 locus (subunits 7+9) while others contained all four subunits, indicating that the material was heterozygous. Pm8 resistance is expressed in the tetraploid 1BL/1RS translocation line based on the reactions of six well-defined powdery mildew isolates. However, Pm8 resistance is not expressed in the hexaploid wheat cultivars 'Olymp', 'Heinrich' and 'Florida', which also contain the 1BL/1RS translocation. Obviously, the existence of the 1BL/1RS translocation is not a proof for the expression of the associated genes. PAGE results did not show a clear linkage between powdery mildew resistance and the presence of 1RS secalins.

The inheritance of lipoxidase activity and pigment content in durum wheat.

Analysis of a 10-parent diallel of durum wheat (Triticum turgidum L. var. durum) grown at two diverse locations revealed that for enzyme lipoxidase activity, wheat and predicted macaroni pigment contents, heterosis was environmentally dependent. Both additive and dominance genetic effects were significant for each of these quality traits studied, but in one location, the additive genetic effect was consistently more pronounced than the dominance genetic effect, while the reverse was the case in the other location. There was no evidence of epistatic gene effect for any of the three characters in either location.

Characterization of agronomic traits and markers of recombinant inbred lines from intra- and interracial populations of Phaseolus vulgaris L.

The value of intra- and interracial populations in common bean (Phaseolus vulgaris L.) needs to be determined in order to create useful genetic variation for maximizing gains from selection, broadening the genetic base of commercial cultivars, and making efficient use of available resources. Five large-seeded parents of race Nueva Granada (N), two small-seeded race Mesoamerica (M), and one medium-seeded race Durango (D) were hybridized to produce one intraracial (N x N) and three interracial (two N x M and one N x D) populations. Seventy-nine F2-derived F6 lines randomly taken from each population along with their parents were evaluated for agronomic traits and markers at Palmira and Popayán, Colombia, in 1990 and 1991. Variation for agronomic traits and for morphological, protein, and isozyme markers was larger in interracial populations than in the intraracial population. Mean seed yield of all lines as well as yield of the highest yielding line from two interracial populations were significantly higher than that of the intraracial population. The highest (≥ 0.80±0.15) heritability was recorded for 100-seed weight. Values for seed yield varied from 0.19±0.17 to 0.50±0.16. Gains from selection (at 20% selection pressure) for seed yield ranged from 3.9% to 11.4%. Seed yield was positively associated with biomass yield, pods/m(2), and days to maturity, but harvest index showed negative correlations with these traits and a positive value with 100-seed weight. Polymorphism was recorded for phaseolin, lectins, protein Group-1 and protein Group-2 fractions, and six isozyme loci. Lines with indeterminate growth habit had significantly (P < 0.01) higher seed yield than lines with determinate growth habit in a Redkloud x MAM 4 population. Also, 23 other associations of markers with agronomic traits other than seed yield were recorded. Of these associations, lines with T phaseolin, the Diap1 (2) allele, and lilac flower color tended to possess greater seed weight.

Gliadin alleles in Canadian western red spring wheat cultivars: use of two different procedures of acid polyacrylamide gel electrophoresis for gliadin separation.

Gliadin allele compositions of 21 Canadian spring common wheat cultivars, most of which belong to the Canada western red spring (CWRS) class, were studied and great similarity in their genotypes was confirmed. It was found that alleles frequent in the set of Canadian wheats (such as Gli-B1d, Gli-D1j, Gli-A2m, and Gli-D2h) are very rare or absent in common wheat cultivars from other regions and countries studied earlier, indicating that germplasm of CWRS cultivars is rather unique. It may be suggested that alleles frequent in Canadian cultivars relate to important technological characteristics of these wheats and may possibly serve as marker genes during selection for quality traits. Similarity of gliadin electrophoregrams obtained by two different acid polyacryl-amide gel electrophoretic procedures for the same genotype was established, and the component composition of allelic variants of blocks of gliadin components found in the set of Canadian cultivars and in standard cultivars Chinese Spring and Bezostaya 1 are described.