Mohammed S. Alamri

Effect of pre-harvest sprouting on physicochemical changes of proteins in wheat.

BACKGROUND High moisture before harvest can cause sprouting of the wheat kernel, which is termed pre-harvest sprouting (PHS). The aim of this study was to examine the variation in physicochemical properties of proteins in PHS-damaged (sprouted) hard red and white spring wheat genotypes. Specifically, protein content, enzyme activity and degradation of proteins were evaluated in sound and PHS-damaged wheat. RESULTS Protein contents of sprouted wheat samples were lower than that of non-sprouted samples; however, their differences were not significantly (P > 0.05) correlated with sprouting score. Sodium dodecyl sulfate (SDS) buffer extractable proteins (EXP) and unextractable proteins (UNP) were analyzed by high-performance size exclusion chromatography. PHS damage elevated endoprotease activity and consequently increased the degradation of polymeric UNP and free asparagine concentration in wheat samples. Free asparagine is known to be a precursor for formation of carcinogenic acrylamide during high heat treatment, such as baking bread. Free asparagine content had significant correlations (P < 0.01) with sprouting score, endoprotease activity and protein degradation. CONCLUSIONS Genotypes with higher endoprotease activity tend to exhibit a larger degree of degradation of UNP and higher free asparagine concentration in sprouted wheat samples.

Effect of okra gum on the pasting, thermal, and viscous properties of rice and sorghum starches.

The effect of okra gum (OE) on the physical properties of rice and sorghum starches was investigated using rapid visco-analyzer (RVA), Brookfield viscometer, differential scanning Calorimetry (DSC), and light microscopy. Starch was replaced with 5, 10, 15% OE weight basis (g/100 g). In the presence of OE, the peak and final viscosity as well as the setback of both starches were reduced. However, the difference between the theoretical and the measured setback was more than just can be attributed to the omitted starch. The DSC data of the blends showed higher peak temperature compared to the control, indicating slower starch gelatinization in the presence of OE. Brookfield profiles demonstrated increase in shear stress at higher shear rate confirming pseudoplasticity of the system (n<1). Over all, it can be assumed that OE has influenced the properties of the starches, particularly, by decreasing viscosity, setback, and pseudoplasticity of the starch gels.

Effect of Pre-Harvest Sprouting on Physicochemical Properties of Starch in Wheat

Pre-harvest sprouting (PHS) in wheat (Triticum aestivum L.) occurs when physiologically mature kernels begin germinating in the spike. The objective of this study was to provide fundamental information on physicochemical changes of starch due to PHS in Hard Red Spring (HRS) and Hard White Spring (HWS) wheat. The mean values of α-amylase activity of non-sprouted and sprouted wheat samples were 0.12 CU/g and 2.00 CU/g, respectively. Sprouted samples exhibited very low peak and final viscosities compared to non-sprouted wheat samples. Scanning electron microscopy (SEM) images showed that starch granules in sprouted samples were partially hydrolyzed. Based on High Performance Size Exclusion Chromatography (HPSEC) profiles, the starch from sprouted samples had relatively lower molecular weight than that of non-sprouted samples. Overall, high α-amylase activity caused changes to the physicochemical properties of the PHS damaged wheat.

Dissection of Genetic Factors underlying Wheat Kernel Shape and Size in an Elite × Nonadapted Cross using a High Density SNP Linkage Map.

Wheat kernel shape and size has been under selection since early domestication. Kernel morphology is a major consideration in wheat breeding, as it impacts grain yield and quality. A population of 160 recombinant inbred lines (RIL), developed using an elite (ND 705) and a nonadapted genotype (PI 414566), was extensively phenotyped in replicated field trials and genotyped using Infinium iSelect 90K assay to gain insight into the genetic architecture of kernel shape and size. A high density genetic map consisting of 10,172 single nucleotide polymorphism (SNP) markers, with an average marker density of 0.39 cM/marker, identified a total of 29 genomic regions associated with six grain shape and size traits; ∼80% of these regions were associated with multiple traits. The analyses showed that kernel length (KL) and width (KW) are genetically independent, while a large number (∼59%) of the quantitative trait loci (QTL) for kernel shape traits were in common with genomic regions associated with kernel size traits. The most significant QTL was identified on chromosome 4B, and could be an ortholog of major rice grain size and shape gene GS3 or qGL3. Major and stable loci also were identified on the homeologous regions of Group 5 chromosomes, and in the regions of TaGW2 (6A) and TaGASR7 (7A) genes. Both parental genotypes contributed equivalent positive QTL alleles, suggesting that the nonadapted germplasm has a great potential for enhancing the gene pool for grain shape and size. This study provides new knowledge on the genetic dissection of kernel morphology, with a much higher resolution, which may aid further improvement in wheat yield and quality using genomic tools.

Genome-wide genetic dissection of supernumerary spikelet and related traits in common wheat

Branched spike or supernumerary spikelet (SS) is a naturally occurring variant in wheat and holds great potential for increasing the number of grains per spike, and ultimately, increasing wheat yield. However, detailed knowledge of the molecular basis of spike branching in common wheat is lacking. In the present study, a recombinant inbred line (RIL) population derived from the cross of an SS accession and an elite non‐SS line was developed and evaluated over four to six environments for seven SS‐related traits to identify the genetic basis of SS in wheat. A framework linkage map was generated using 939 diversity arrays technology (DArT) markers. Composite interval mapping (CIM) identified a total of seven consistent quantitative trait loci (QTL) located on five chromosomes (2D, 5B, 6A, 6B, and 7B), suggesting a polygenic inheritance of SS. The phenotypic variation explained (PVE) by individual QTL ranged from 3.3 to 37.3%. The QTL located on 2D (QSS.ndsu‐2D) and 7B (QSS.ndsu‐7B.2) have major effects (PVE > 15%), while the remaining five QTL (QSS.ndsu‐5B, QSS.ndsu‐6A, QSS.ndsu‐6B.1, QSS.ndsu‐6B.2, QSS.ndsu‐7B.1) have minor effects (PVE < 15%). Comparison of the genomic locations of the QTL suggested that QSS.ndsu‐2D was located in the same regions on 2DS, where QTL for several traits have been reported. However, the remaining six QTL for SS are reported for the first time. Multiple interval mapping (MIM) showed that all seven QTL are involved in epistatic interaction. The major genomic regions controlling these SS‐related traits may prove invaluable for wheat improvement and could also be the target for future studies aimed at cloning these genes.

Genome-Wide Mapping of Spike-Related and Agronomic Traits in a Common Wheat Population Derived from a Supernumerary Spikelet Parent and an Elite Parent

In wheat, exotic genotypes harbor a broad range of spike‐related traits, and can be used as a source of new genes for germplasm enhancement in wheat breeding programs. In the present study, a population of 163 recombinant inbred lines was derived from a cross between an elite line (WCB414) and an exotic line (WCB617) with branched spike (supernumerary spikelet; SS) head morphology. The population was evaluated over four to six environments to identify quantitative trait loci (QTL) associated with nine spike‐related traits and 10 agronomic traits. A genetic map consisting of 939 diversity arrays technology (DArT) markers was constructed. Composite interval mapping identified a total of 143 QTL located on 17 different wheat chromosomes and included 33 consistent and definitive QTL. The amount of phenotype variation explained (PVE) by individual QTL ranged from 0.61 to 91.8%. One major QTL for glume pubescence was located in a QTL‐rich region on the short arm of chromosome 1A, where loci for other traits such as for kernels per spike (KS) and spike length (SL) were also identified. Similarly, a cluster of QTL associated with yield‐related, agronomic and spike‐related traits contributing up to 40.3% of PVE was found on the short arm of chromosome 2D, in the vicinity of a major QTL for SS‐related traits. Consistent and major QTL identified in the present study may be useful in marker‐assisted breeding programs to facilitate transfer of desirable alleles into other germplasm. Desirable QTL alleles were also contributed by the exotic line, suggesting the possibility of enriching the breeding germplasm with alleles from SS genotypes.

Genetic analysis and mapping of seedling resistance to Septoria tritici blotch in ‘Steele-ND’/‘ND 735’ bread wheat population

Septoria tritici blotch (STB) caused by Mycosphaerella graminicola, is one of the most destructive foliar diseases of wheat (Triticum aestivum L.) especially in temperate and humid regions across the world. The susceptibility of recently released varieties, evolution of resistance to fungicides and increasing incidence of STB disease emphasizes the need to understand the genetics of resistance to this disease and to incorporate host resistance into adapted cultivars. This study aimed to decipher the genetics and map the resistance to STB using a recombinant inbred line (RIL) mapping population derived from ‘Steele-ND’ (susceptible parent) and ‘ND 735’ (resistant parent). The RILs were evaluated in three greenhouse experiments, using a North Dakota (ND) isolate of STB pathogen. The mean disease severity of parental genotypes, ‘ND 735’ (11.96%) and ‘Steele-ND’ (66.67%) showed significant differences (p < 0.05). The population segregated for STB and the frequency distribution of RILs indicated quantitative inheritance for resistance. The mean disease severity in RILs ranged from 0 to 71.55% with a mean of 21.98%. The genome map of this population was developed using diversity array technology (DArT) and simple sequence repeat (SSR) markers. The framework linkage map of this population was developed using 469 molecular markers. This map spanned a total distance of 1,789.3 cM and consisted of 17 linkage groups. QTL mapping using phenotypic data and the framework linkage maps detected three QTL through composite interval mapping. One QTL was consistently detected in all experiments on the long arm of chromosome 5B, and explained up to 10.2% phenotypic variation. The other two QTLs, detected in single environments, were mapped to 1D and 7A and explain 13% and 5.5% of the phenotypic variation, respectively. The map position of the consistent QTL on 5BL coincides with the map position of durable resistance gene Stb1 suggesting the importance of this region of ‘ND 735’ as a source of durable STB resistance for the wheat germplasm.

Assessing spring wheat quality using the glutograph instrument.

Proteins are among the primary factors responsible for the variation in wheat quality (39,40). Protein content of wheat grain of a specific cultivar depends on agronomic and environmental factors (4,6,24). Protein quality, on the other hand, is primarily a genotypic trait and can also be affected by certain environmental stress conditions. Wheat proteins comprise an extremely heterogeneous mixture of molecular species with different properties and functions in the wheat grain (7,41). Increase in protein content is normally associated with increased dough strength and improved baking quality of bread wheat (18). The functional properties of wheat depend on the structure of the various types of proteins that form the gluten complex, their interaction with each other, and their interaction with other wheat components (35,39). Rheological properties are significant in determining the behavior of wheat flour dough during mechanical handling, in addition to their influence on the quality of ABSTRACT

Black cumin-fortified flat bread: formulation, processing, and quality

Black cumin (BC) (Nigella sativa) defatted meal was added at 5, 10, and 15% to whole wheat flour (WWF) in flat bread formulation so that to deliver daily intake of zinc, potassium, phosphorous, iron, and copper as well as high protein content. BC is known for its anticancer activities, immune stimulation, anti-inflammation, anti-hypertensive, anti-microbial, anti-parasitic, antioxidant and hypoglycemic. Although the water holding capacity of BC was twice as much as WWF, BC has minimal effect on the water absorption of WWF. The farinograph mixing tolerance index of the WWF dough has increased up to 133%, whereas dough stability has decreased by 41%. The extensibility of the control dough was not significantly (P?0.05) affected by BC, but the resistance to extension was reduced. The higher amylograph gelatinisation temperature indicates delay on starch granule swelling, but the peak viscosity dropped as a function of BC content, while the final viscosity was unchanged. By consuming one piece of this bread, ...

Gelatinisation kinetics of corn and chickpea starches using DSC, RVA and dynamic rheometry

The gelatinisation kinetics (non-isothermal) of corn and chickpea starches at different heating rates were calculated using differential scanning calorimetry (DSC), rapid visco analyser (RVA), and oscillatory dynamic rheometry. The data obtained from the DSC thermogram and the RVA profiles were fitted to Kissingers and Ozawas methods. Starch gelatinisation was characterised by two phases, where the first corresponded to the unfolding of amorphous region of the starch granule and the other represented the melting crystalline part. The temperature that separates the unfolding and melting of the granule parts, the breaking temperature, was recorded. Higher activation energy (Ea) was calculated for the DSC data versus the RVA. The Ea values calculated by Kissingers method indicated that one can use either DSC or RVA to get a comparable Ea for both starches, whereas Ozawas method showed comparable results for chickpea starch and less comparable for corn starch. The Ea of corn starch as calculated by dynami...