Variation in quality traits in common wheat as related to Chinese fresh white noodle quality

The variation in grain compositional traits related to Chinese fresh white noodle (CFWN) quality was examined in 25 leading Chinese common wheat cultivars and advanced lines. Large variations were observed in flour yield, flour particle size, protein and ash contents, farinograph and rapid visco-analyzer (RVA) parameters, flour colour components, and polyphenol oxydase (PPO) activity. An improved sensory method was proposed for adequately evaluating CFWN quality of common wheat flour based on methodology used in the Japanese quality scoring system for white salted noodles, but with major modifications in the score weight given to each noodle quality parameter. Large differences in CFWN quality were observed among Chinese wheat cultivars. The correlation coefficients (r) between starch paste breakdown (RVA) and noodle viscoelasticity and smoothness were 0.63 and 0.59, respectively, suggesting that in breeding wheat for high CFWN quality, the starch pasting properties are of major importance. Low ash content was significantly correlated (r = – 0.66) with bright white noodle colour.     

Use of recombinant substitution lines for gene mapping and QTL analysis of bread making quality in wheat

Three populations of 41 to 74 homozygous recombinant substitutionlines (RSLs) were used for RFLP mapping and quantitative trait analysis ofthe following parameters: total proteins (%prot), SDS-sedimentationvolume (SDSsed), bread mixing time (Bmxt) and loaf volume (Blvol). TheRSLs were developed from crosses between disomic substitution linesinvolving chromosomes 1A, 1B, and 1D of the high-quality wheat cv.`Cheyenne' (Cnn) substituted into the genetic background of the poorquality cv. `Chinese Spring' (CS). The QTL analysis indicated regions in thethree chromosomes responsible for the differences between CS and thethree disomic substitution lines. The major effect detected on chromosome1A of Cnn was high SDSsed, Bmxt and Blvol associated with the H-M-WGlutenin subunit locus Glu-A1. In addition a QTL was identifieddistally on the long arm of chromosome 1A for Bmxt and Blvol. Ahigh %prot QTL was mapped on the long arm of chromosome 1B of CSand a high Bmxt QTL was mapped on the long arm of chromosome 1B ofCnn. Additionally, this chromosome enhanced SDSsed, Bmxt and Blvol,which were associated with the region of the gliadin and L-M-W Gluteninsubunit locus Gli-B1/Glu-B3. A second more proximal region on theshort arm of chromosome 1B could be involved in loaf volume. QTLanalyses for% prot, showed a strong clear QTL mapped in the centromericregion (XTri/Centromere linkage group) of chromosome 1D with anapparent positive effect brought by CS. For Blvol we revealed two QTLs inopposite phase: one in the Xtri/Centromere region with a positive effect ofCS allele, one in the Glu-D1 region with a positive effect of Cnnallele. This organization `in repulsion' in the parental lines could explain thesmall difference between them for Blvol and the significant transgressionobserved among the RSLs. No clear candidate gene explained the positiveeffect of the centromeric region of CS on %prot and Blvol. Contrary to thecurrent belief that wheat bread-making quality is determined primarily byvariation at the Glu-1 locus, present results showed that the trait isunder a complex control and the Glu-1 loci was only a component ofthe genetic control of the trait.     

The bread wheat races of bunt represented in the Australian bunt collection

Summary The Australian Bunt Collection, obtained from infected crops between 1962–1977, has been classified into races, based on the differential reactions to ten known bunt resistant genes. Eight physiologic races of Tilletia laevis and three of T. tritici were identified. No race had virulence against the genes Bt3, Bt5, Bt8, or Bt10, of wheat. Consequently four major genes are available for breeding Australian wheat cultivars with resistance to common bunt.     

Genetic control of in vitro regeneration in alfalfa (Medicago sativa L.)

Summary Cultivars of common wheat (Triticum aestivum L.) and durum wheat (T. turgidum L. var. durum) were evaluated for epicuticular wax content and its relationship with spectral reflectance. Epicuticular wax is associated with drought tolerance. Highly significant differences (1.51 to 2.80 mg/dm²) were found in the amount of epicuticular wax (EW) among the cultivars. Water stress significantly enhanced the level of EW. EW content under stress and control conditions were positively correlated (r=0.85, p<0.01) suggesting that selection for this trait could be practised in either environment. Surface reflectance was reduced when the waxy layer from the leaf was removed with chloroform. The reduction for the abaxial surface was twice that for the adaxial surface indicating that the abaxial surface was more waxy than the adaxial one. The mean reduction (both surfaces) termed was positively correlated with the amount of EW (r=0.59, p<0.01).     

Genetic variation and interrelationships of agronomic characters in landraces of bread wheat from southeastern Iran

There is renewed interest in wheat landraces as important sources of genetic variation for agronomic characters. Fifty-three pure lines of bread wheat (Triticum aestivum L.) derived from seven landraces collected from southeastern Iran were used to estimate genetic variation and heritability for 13 developmental and quantitative characters. Path-analysis was used to partition the genetic correlations between grain yield and six grain yield-related traits. Mean values of landraces were also compared with three improved cultivars from California and Iran. Genotypic differences among the landraces and among the pure lines collected from the landraces were highly significant for all characters considered. Compared with the modern cultivars, the landrace genotypes were, on average, later in days to heading and taller than the cultivars but had lower values for number of grains per spike, 1000-grain weight, grain yield and harvest index. Some landrace genotypes were similar to the modern cultivars for grain yield. Moderate to high genetic variation was displayed by number of grains per spike, number of spikes per plant, 1000-grain weight, and harvest index. The heritability estimates ranged from 59% for grain yield to 99% for days to anthesis. Expected genetic advance (as % of the mean) was ≈34% for number of spikes per plant, number of grains per spike, and 1000-grain weight. Days to heading and to anthesis correlated positively with number of spikes per plant, shoot biomass, and straw biomass but negatively with number of grains per spike and harvest index. The strong direct effect of number of spikes per plant on grain yield was completely counterbalanced by its indirect negative effects via number of grains per spike and 1000-grain weight. Number of grains per spike and 1000-grain weight were positively correlated with grain yield, and they had large direct effects. These two characters, however, were negatively correlated and exhibited a substantial counterbalance effect via one another and via number of spikes per plant. The landraces could be improved by intercrossing the promising genotypes identified in this study, with simultaneous selection for earliness, fewer number of spikes per plant, greater number of grains per spike and heavier grains. For further improvement, crossing programs between the landraces and introduced germplasm may be necessary. This revised version was published online in July 2006 with corrections to the Cover Date.     

Genetic effects of Vrn genes on heading date and agronomic traits in bread wheat

Summary The Vrn1, Vrn2 and Vrn3 genes have different values of effects on heading date and related yield components. The genetic background and environment do not affect the ranking of Vrn genotypes according to earliness within near-isogenic line sets; however, they do influence the level of differences between heading dates of particular genotypes and between effect values, respectively. The frequencies of defined Vrn genotypes in the global set of spring bread wheat cultivars are associated with grain weight per plant predicted on the basis of Vrn gene effects averaged over backgrounds and over environments. Peculiarities of backgrounds and environments alter the grain yield ranges of Vrn genotypes. For early photoperiod-insensitive wheats, planted in stress conditions at grain filling, the highest yield was predicted for double dominant Vrn genotypes with Vrn3. This gene is rarely used by the breeders in middle latitudes and its wider adoption is encouraged.     

Studies on multilines in wheat (Triticum aestivum L.).12. Breeding of a multiline variety by convergence of breeding lines

Summary The variation among the component lines of the KSML 3 (a multiline based on cultivar Kalyansona, spring bread wheat) was studied for agronomic characteristics. For days to earing and plant height the variation was small. This helped in imparting uniformity to the multiline. The lines had an improved tillering ability and had larger seeds. This partially explained the increased yield potential of the multiline as compared with Kalyansona.All the lines were susceptible only to one or two races of the yellow and brown rust. In no case any race was virulent against all the lines. In the field all the lines were resistant to both rusts.     

Alien introgression of spring habit dominant genes into bread wheat

Summary Alien dominant genes of spring habit were introgressed into bread wheat. The introgression was undertaken by simple crossing of winter bread wheat to related spring species or genera, followed by backcrossing to winter bread wheat, and did not involve the use of the ph mutants or embryo culture. The introgressed genes were located mostly on chromosomes of homoeologous group 5, and were allelic to the known Vrn genes in bread wheat. Nevertheless three groups of lines were discovered with the genes possibly located on other chromosomes. These genes were non-allelic to each other and to known Vrn genes and were designated Vrn6 ^Sc , Vrn7 ^Sc (introgressed from Secale cereale) and Vrn8 ^Ts (from Triticum sphaerococcum).     

Identification of GA-insensitive Rht genes in Japanese modern varieties and landraces of wheat

Summary GA-insensitive Rht genes of 18 Japanese modern varieties and landraces were identified. Out of 12 modern varieties tested 6 carried only Rht1, and the other 6 carried only Rht2. No varieties carried both Rht1 and Rht2 or Rht3. The geographical distribution of the Rht genotypes in the Japanese modern varieties was clearly localized. All 6 landraces tested carried only Rht2.