Zhiying Deng

Effect of gluten on pasting properties of wheat starch.

The effect of gluten on pasting properties of wheat starch was studied to provide a scientific basis for the application of gluten in food production and quality improvement in wheat breeding. The pasting properties of blends were analyzed using PH1391 wheat starch mixed with five different additions of three kinds of gluten (strong-, medium-, and weak-gluten) and the structures of network were observed with microscope. The significant downtrends of peak viscosity, trough viscosity, final viscosity, area of viscosity, setback, and peak time were observed with the increase in the addition of gluten. In general, the average value of them decreased respectively by 3.6, 4.8, 3.4, 3.8, 4.0, and 1.18% of those corresponding indexes of pure starch for every 2% increase in gluten. The decreasing rate of the indexes mentioned above exceeded more than 2% except peak time, but there were no significant influence of gluten addition on breakdown, pasting temperature and pasting time. The inter layer composed of gluten was not observed when the addition of gluten was 10%, as the compound formed of gluten inlaid in the paste of starch, but obvious inter layer was detected when the addition of gluten was 18%. There was significant or remarkable difference among the effects of three different kinds of gluten on the peak viscosity, trough viscosity, area of viscosity, setback, and peak time, but it had no significant difference among the effects of different glutens on pasting temperature and pasting time. The descending order of the effect of different glutens on peak viscosity, trough viscosity, and area of viscosity was strong-, medium-, and weak-gluten, but the order of them for setback was opposite. Both addition and types of gluten significantly affected peak viscosity, trough viscosity, area of viscosity, setback, and peak time, but there were no significant effects of it on peak time and peak temperature.

Effects of enzymatic hydrolysis of protein on the pasting properties of different types of wheat flour.

As one of the most effective methods to modify proteins, enzymatic hydrolysis is used widely in the preparation of wheat products in the food industry. During the same process, starch pasting occurs frequently. The effects of wheat protein hydrolysis with papain, pepsin, and trypsin on the pasting properties of 3 different kinds of flour were investigated in 5 concentrations. Results showed that the peak viscosity, trough, final, and integral area of pasting curve of these flours decreased with increasing enzymatic hydrolysis of protein, and decreased significantly with the increasing enzyme concentrations. Medium-gluten flour was the least sensitive to enzymatic activity and weak-gluten the most sensitive. Downtrends appeared with increasing papain and trypsin concentrations in the form of breakdown. Enzymes had no significant different effect on the peak times of strong- and medium-gluten flour, but prolonged peak time slightly in weak-gluten flour. The pasting time and temperature of strong- and medium-gluten flour were significantly increased in a concentration-dependent manner. However, there were no significant effects on the pasting times of weak-gluten flour. These results could supply a basis for utilization of enzymatic hydrolysis of wheat protein in food industry and for further studies into the interactions between hydrolyzed protein and starch in food or processing industries.

Genetic dissection of the developmental behaviour of total starch content and its components in wheat grain

Abstract. Starch in wheat is an important component of flour and is related to grain yield and wheat end-products. In this study, a doubled haploid (DH) population with 168 lines derived from a cross of elite Chinese wheat (Triticum aestivum L.) cultivars Huapei 3 and Yumai 57 was used to identify dynamic quantitative trait loci (QTLs) for total starch content (TSC), amylose (AMS) and amylopectin (AMP) in wheat grain. Traits were measured at stages, grown under three treatments in two seasons, and were assessed by unconditional and conditional QTL analyses. Thirty-three additive QTLs and 21 pairs of epistatic QTLs for TSC, AMS and AMP were detected by unconditional mapping, whereas 19 additive QTLs and 15 pairs of epistatic QTLs were identified by conditional mapping. Of these, QTsc4A.1 and QAms4A.1 were detected continuously at five stages under three treatments in two seasons by unconditional mapping, indicating that the accumulated effects of these QTLs were expressed stably from 12 days after flowering (DAF) and were little affected by nitrogen and water agronomic treatment. These two QTLs also showed net expression from 12 to 22 DAF by conditional mapping. The results indicate that the two loci play an important role in starch synthesis. Most of the epistatic QTLs belonged to a minor QTL, but played an important role in the target traits. Therefore, the development of starch is mainly affected by additive effects besides the epistasis effect. The data are useful for potential marker-assisted selection and cloning of the target gene in further fine mapping, and provide a foundation to understand the genetic mechanism underlying the development of starch in wheat and to increase yield.

Genetic dissection reveals effects of interaction between high-molecular-weight glutenin subunits and waxy alleles on dough-mixing properties in common wheat

The glutenin and waxy loci of wheat are important determinants of dough quality. This study was conducted to evaluate the effects of high-molecular-weight glutenin (HMW-GS) and waxy alleles on dough-mixing properties. Molecular mapping was used to investigate these effects on Mixograph properties in a population of 290 (Nuomai1 × Gaocheng8901) recombinant inbred lines (RILs) from three environments in the harvest years 2008, 2009 and 2011. The results indicated the following: (i) the Glu-A1 and Glu-D1 loci have greater impacts on Mixograph properties compared to the Wx-1 loci and the effects of Glu-D1d and Glu-D1h on dough mixing are better than those of Glu-D1f and Glu-D1new1 in this population; (ii) the interactions between the Glu-1 and Wx-1 loci affected some traits, especially the midline peak value (MPV), and the lack of Wx-B1 or Wx-D1 led to increased MPV for all types of Glu-1 loci; and (iii) 30 quantitative-trait loci (QTL) over nine wheat chromosomes were identified with ICIM analysis based on the genetic map of 498 loci. Eight major QTL and 16 QTL in the Glu-1 loci from the three environments were found. The major QTL clusters were associated with the Glu-1 loci, and also were found in two regions on chromosome 3B and one region on chromosome 6A, which is one of the novel chromosome regions influencing dough-mixing strength. The two QTL for MPV are located around Wx-B1 on chromosome 4A. QMPT-1D.1, QMPI-1D.1 and Q8MW-1D.1 were stable in different environments and could potentially be used in molecular marker-assisted breeding.

Genomewide association study for seeding emergence and tiller number using SNP markers in an elite winter wheat population

Seeding emergence and tiller number are the most important traits for wheat (Triticum aestivum L.) yield, but the inheritance of seeding emergence and tillering is poorly understood. We conducted a genomewide association study focussing on seeding emergence and tiller number at different growth stages with a panel of 205 elite winter wheat accessions. The population was genotyped with a high-density Illumina iSelect 90K SNPs assay. A total of 31 loci were found to be associated with seeding emergence rate (SER) and tiller number in different growth stages. Loci distributed among 12 chromosomes accounted for 5.35 to 11.33% of the observed phenotypic variation. With this information, 10 stable SNPs were identified for eventual development of cleaved amplified polymorphic sequence markers for SER and tiller number in different growth stages. Additionally, a set of elite alleles were identified, such as Ra_c14761_1348-T, which may increase SER by 13.35%, and Excalibur_c11045_236-A and BobWhite_c8436_391-T, which may increase the rate of available tillering by 14.78 and 8.47%, respectively. These results should provide valuable information for marker-assisted selection and parental selection in wheat breeding programmes.

Discovery of Consistent QTLs of Wheat Spike-Related Traits under Nitrogen Treatment at Different Development Stages

Spike-related traits such as spike length (Sl), fertile spikelet number (Fsn), sterile spikelet number (Ssn), grain number per spike (Gns), and thousand-kernel weight (Tkw) are important factors influencing wheat yield. However, reliably stable markers that can be used for molecular breeding in different environments have not yet been identified. In this study, a double haploid (DH) population was used for quantitative trait locus (QTL) mapping of five spike-related traits under four different nitrogen (N) supply dates in two locations and years. Seventy additive QTLs with phenotypic variation ranging from 4.12 to 34.74% and 10 major epistatic QTLs were identified. Eight important chromosomal regions on five chromosomes (1B, 2B, 2D, 5D, and 6A) were found. Sixteen stable QTLs were detected for which N application had little effect. Among those stable QTLs, QSl.sdau-2D-1, and QSl.sdau-2D-2, with phenotypic variation explained (PVE) of 10.4 and 24.2%, respectively, were flanked by markers Xwmc112 and Xcfd53 in the same order. The QTLs QSsn.sdau-2B-1, QFsn.sdau-2B-1, and QGns.sdau-2B, with PVE ranging from 4.37 to 28.43%, collocated in the Xwmc179-Xbarc373 marker interval. The consistent kernel wheat QTL (QTkw.sdau-6A) on the long arm of chromosome 6A, flanked by SSR markers Xbarc1055 and Xwmc553, showed PVE of 5.87–15.18%. Among these stable QTLs, the two flanking markers Xwmc112 and Xcfd53 have been validated using different varieties and populations for selecting Sl. Therefore, these results will be of great value for marker-assisted selection (MAS) in breeding programs and will accelerate the understanding of the genetic relationships among spike-related traits at the molecular level.

Genetic Detection of Main Yield Traits in Wheat

Yield and related traits controlled by multiple genes are the most important goal of wheat breeding. In this chapter, QTL mapping was used to detect yield and related traits, such as thousand-grain weight and spike-related traits (spike length, grain number per spike, spikelets per spike, fertile spikelets per spike, sterile spikelets per spike, compactness, and spike weight). The QTL results may facilitate yield improvement through molecular marker-assisted selection.

Genetic Detection of Main Quality Traits in Wheat

Wheat quality is one of the important breeding objectives for wheat breeders, but most of the major genes controlling these traits are unclear. So in this chapter, grain quality traits, nutritional quality traits, flour quality traits, dough quality traits, and processing quality traits were genetically dissected by QTL mapping. Of which, grain quality included grain weight, grain length, diameter, and hardness; nutritional quality presented protein content, beneficial mineral elements, amino acid content and components, and carotenoid pigments; flour quality contained gluten content and index, flour whiteness and color, PPO activity, sedimentation volume, paste viscosity parameters, falling number, starch content and components; for dough quality, farinograph, mixograph and alveograph parameters were involved; and processing quality mainly discussed Chinese noodle and steamed bread quality. Some major QTLs identified for wheat quality traits provided important genetic and molecular information for marker-assisted selection breeding.

Genetic Analysis of Main Physiological and Morphological Traits

Wheat physiological and morphological traits are the most important traits for wheat (Triticum aestivum L.) yield. In this chapter, quantitative trait loci (QTL) mapping for physiological traits including photosynthetic Characters, microdissection characteristics of Stem, heading date and cell membrane permeability of leaf, and for morphological traits of containing root-related traits and leaf-related traits were analyzed in different environments using the DH population, RIL population or natural population. Photosynthesis related traits of wheat were mapped under field and phytotron environments, respectively. Eight additive QTLs and three pairs of epistatic QTLs for chlorophyll were detected in field environments and 17 additive QTLs for conferring photosynthesis and its related traits were identified in phytotron environments. Furthermore, 18 additive loci for dry matter production (DMA) and Fv/Fm were detected. For microdissection characteristics of wheat stem, a total of 12 QTLs controlling anatomical traits of second basal internode on chromosomes 1B, 4D, 5B, 5D, 6A and 7D, and 20 additive QTLs for anatomical traits of the uppermost internode on chromosomes 1A, 1B, 2A, 2D, 3D, 4D, 5D, 6A, 6D and 7D were detected based on DH population. Two additive QTLs on chromosomes 1B and 5D in DH population, five additive QTLs on chromosomes 3B, 5B, 6A, 6B and 7D in RIL population derived from the cross of Nuomai 1 × Gaocheng 8901 and 12 additive QTLs on chromosomes 1A, 1B, 4B, 6A and 6B based on a RIL population derived from the cross of Shannong 01-35 × Gaocheng 9411 were identified for heading date. For cell membrane permeability of leaf, a total of 21 additive QTLs were detected on chromosomes 1B, 2A, 3A, 3B, 5B, 6A, 6B, 6D, 7B and 7D, respectively in three different environments based on a DH population. Seven additive QTLs and 12 pairs of epistatic QTLs for root-related traits were mapped on chromosomes 1A, 1D, 2A, 2B, 2D, 3A, 3B, 5D, 6D and 7D using IF2 population derived from Huapei 3 × Yumai 57.31 additive QTLs and 22 pairs of epistatic QTLs conferring leaf morphology were detected based on a DH population. Finally, by genome-wide association analysis with a natural population derived from the founder parent Aimengniu and its progenies, 61 marker-trait associations (MTAs) involving 46 DArT markers distributed on 14 chromosomes (1B, 1D, 2A, 2B, 2D, 3A, 3B, 4A, 5B, 6A, 6B, 6D, 7A and 7B) for leaf-related traits were identified and the R2 ranges from 0.1 to 16.4 %. These results provide a better understanding of the genetic factors for wheat physiological and morphological traits and facilitate marker-assisted selection strategy in wheat breeding.

Genetic Dissection of Stress-Tolerance Traits in Wheat

Wheat (Triticumaestivum L.) growth and its productivity were always affected by abiotic or biotic stress. Especially, drought, salinity, waterlogging and disease often cause severe reductions in wheat yield. Therefore, it is greatly important to discover resistant genes in wheat. In this chapter, drought resistance, heavy metals resistance (cadmium and chromium stress), pre-harvest sprouting resistance, disease resistance (adult-plant resistance to powdery mildew, fusarium head blight resistance), salt resistance and potassium resistance were genetically dissected by QTL mapping. Some major QTLs identified in this chapter could provide important genetic and molecular information for marker-assisted selection breeding in wheat.