Breeding for increased grain protein and micronutrient content in wheat: Ten years of the GPC-B1 gene

To provide food and nutrition security for a growing world population, continued improvements in the yield and nutritional quality of agricultural crops will be required. Wheat is an important source of calories, protein and micronutrients and is thus a priority to breed for improvements in these traits. The GRAIN PROTEIN CONTENT-B1 (GPC-B1) gene is a positive regulator of nutrient translocation which increases protein, iron and zinc concentration in the wheat grain. In the ten years since it was cloned, the impacts of GPC-B1 allelic variation on quality and yield traits have been extensively analyzed in diverse genetic backgrounds in field studies spanning forty environments and seven countries. In this review, we compile data from twenty-five studies to summarize the impact of GPC-B1 allelic variation on fifty different traits. Taken together, the results demonstrate that the functional copy of the GPC-B1 gene is associated with consistent positive effects on grain protein, Fe and Zn content with only marginally negative impacts on yield. We conclude that the GPC-B1 gene has the potential to increase nutritional and end use quality in a wide range of modern cultivars and environments and discuss the possibilities for its application in wheat breeding.     

Methyl bromide alternatives for strawberry and tomato pre-plant uses: A meta-analysis

This paper reports the results of a meta-analytic synthesis of information from a large number of horticultural experiments that evaluated the technical feasibility of methyl bromide alternatives as soil fumigants in strawberry (Fragaria ananassa) cultivation in California, Florida, and Spain, and in tomato (Solanum lycopersicum) cultivation in Florida. A technically feasible alternative is defined as a treatment that provides pest control and crop yields similar to methyl bromide standard fumigation. We selected papers using five criteria, which jointly ensured inclusion of field experiments that contained usable information on at least three treatments—(1) an untreated control, (2) a methyl bromide treatment, and (3) a treatment that is an alternative to methyl bromide treatment. Because of the differences in regional cropping environments, we performed separate meta-analyses for four crop/region combinations. To explore the potential effects of missing information on past fumigation history and pest pressure on the results, we performed two sensitivity analyses, in which the set of usable field experiments included only those experiments in which the improvement of the methyl bromide treatment yield over the control yield was either 15% or 50%. Finally, the definition of several potential alternative chemical treatments took into account differences in formulations and application rates. The results we obtained do not support the technical superiority of methyl bromide over its alternatives. We found several potential alternatives for which we could not reject the hypothesis of technical feasibility, based on the experimental data for strawberries in California and Spain. In particular, the results on strawberry field experiments in California indicate that the estimated effect size of the treatment using 1,3-dichloropropene/chloropicrin 65:35 formulation (applied at the standard rate) was close to the estimated effect size for methyl bromide. The results from strawberry and tomato field experiments in Florida were inconclusive. However, this does not establish that methyl bromide is technically superior to its alternatives. Given the data-related limitations of the analysis, standard protocols are necessary for conducting and reporting the experiments to allow for more meaningful synthesis of the experimental data.     

Hull to caryopsis adhesion and grain skinning in malting barley: Identification of key growth stages in the adhesion process

Strong adhesion between the hull and the caryopsis is essential for barley to be of good malting quality. Poor hull adhesion, a condition known as grain skinning, is undesirable for malting and downstream processes. At present, the processes mediating hull adhesion during grain development are poorly understood. The barley cultivar Chariot was grown in greenhouse conditions and grain development was recorded at defined growth stages to examine the timing of hull adhesion. Initiation of adhesion was first observed when caryopsis fresh weight and volume were approaching their maximum at 19 days after anthesis, during early dough. Hull adhesion was complete by 27 days after anthesis, or soft dough. Sections of developing grains were observed using light and transmission electron microscopy to examine a lipid-rich cementing layer believed to be responsible for adhesion between the hull and the pericarp. Evidence for a lipid-rich cementing material was supported by the observation that neither pectinase nor cellulase effected hull loosening. Grain growth, the presence of globular material originating from the pericarp and an electron dense material in the cementing layer are discussed in relation to hull adhesion. Grain skinning could be caused by poor adherence of cuticular material or inadequate fusion between cuticles.     

Characterisation of starch during germination and seedling development of a rice mutant with a high content of resistant starch

To acquire a better understanding of whether RS influences the dynamics of in vivo starch digestion and seed vigour, the high-RS rice mutant RS4 (RS ca. 10%) and the wild type R7954 were used to investigate total amylase activity, seedling vigour, starch content and starch granule structure during germination. RS4 exhibited similar seed vigour to R7954. Amylose and amylopectin in R7954 showed synchronous degradation throughout the whole process, while amylopectin was hydrolysed significantly faster than amylose in RS4 during the earlier germination stages. The starch residues of RS4 after germination (GD) lost endotherm peaks and showed a special X-ray diffraction pattern with only two peaks at around 16.90° and 21.62°, probably due to remnants of amylopectin and its tight crosslinking with the cell wall. The remaining starch after 10 GD, primarily amylopectin may make a critical contribution to total resistant starch content. These results indicated that RS had no negative impact on seed vigour in rice lines, although RS cannot be hydrolysed by α-amylase from human and animal in vitro. By appropriately increasing the special amylopectin fraction, a new breeding programme of high RS crops and improvement in the eating quality of high RS rice varieties might be achieved.     

Combined mutations in five wheat STARCH BRANCHING ENZYME II genes improve resistant starch but affect grain yield and bread-making quality

Increases in the proportion of amylose in the starch of wheat grains result in higher levels of resistant starch, a fermentable dietary fiber associated with human health benefits. The objective of this study was to assess the effect of combined mutations in five STARCH BRANCHING ENZYME II (SBEII) genes on starch composition, grain yield and bread-making quality in two hexaploid wheat varieties. Significantly higher amylose (∼60%) and resistant starch content (10-fold) was detected in the SBEII mutants than in the wild-type controls. Mutant lines showed a significant decrease in total starch (6%), kernel weight (3%) and total grain yield (6%). Effects of the mutations in bread-making quality included increases in grain hardness, starch damage, water absorption and flour protein content; and reductions in flour extraction, farinograph development and stability times, starch viscosity, and loaf volume. Several traits showed significant interactions between genotypes, varieties, and environments, suggesting that some of the negative impacts of the combined SBEII mutations can be ameliorated by adequate selection of genetic background and growing location. The deployment of wheat varieties with increased resistant starch will likely require economic incentives to compensate growers and millers for the significant reductions detected in grain and flour yields.     

Genome-wide association mapping of starch granule size distribution in common wheat

Starch is a crucial component in wheat endosperm and plays an important role in processing quality. Endosperm of matured wheat grains contains two distinct starch granules (SG), referred to as larger A- and smaller B-granules. In the present study, 166 Chinese bread wheat cultivars planted in four environments were characterized for variation in SG size. A genome-wide association study (GWAS) using the 90 K SNP assay identified 23 loci for percentage volumes of A- and B-granules, and 25 loci for the ratio of A-/B-granules volumes, distributing on 15 chromosomes. Fifteen MTAs were associated with both the percentage volumes of A-, B-granules and the ratio of A-/B-granules volumes. MTAs IWB34623 and IWA3693 on chromosome 7A and IWB22624 and IWA4574 on chromosome 7B associated with the percentage volumes of A- and B-granules consistently identified in multiple environments were considered to be stable. Linear regression analysis showed a significantly negative correlation of the number of favorable alleles with the percentage volumes of A-granules and a significantly positive correlation between the number of favorable alleles and the percentage volumes of B-granules, respectively. The loci identified in this study and associated markers could provide basis for manipulating SG size to obtain superior noodle quality in wheat.     

Effect of high molecular weight glutenins and rye translocations on soft wheat flour cookie quality

The influence of high molecular weight glutenin subunits (HMW-GS) on wheat breadmaking quality has been extensively studied but the effect of different Glu-1 alleles on cookie quality is still poorly understood. This study was conducted to analyze the effect of HMW-GS composition and wheat-rye translocations on physicochemical flour properties and cookie quality of soft wheat flours. Alleles encoded at Glu-A1, Glu-B1 and Glu-D1 locus had a significant effect over physicochemical flour properties and solvent retention capacity (SRC) profile. The null allele for Glu-A1 locus presented the highest cookie factor observed (CF = 7.10), whereas 1BL/1RS and 1AL/1RS rye translocations had a negative influence on CF. The three cultivars that showed the highest CF (19, 44 and 47) had the following combination: Glu-A1 = null, Glu-B1 = 7 + 8, Glu-D1 = 2 + 12 and no secalins. Two prediction equations were developed to estimate soft wheat CF: one using the HMW-GS composition and the other using physicochemical flour parameters, where SRCsuc, SRC carb, water-soluble pentosans, damaged starch and protein turned out to be better CF predictors. This data suggests that grain protein allelic composition and physicochemical flour properties can be useful tools in breeding programs to select soft wheat of good cookie making quality.     

Sorghum extrusion process combined with biofortified sweet potato contributed for high iron bioavailability in Wistar rats

This study aimed to evaluate the effect of sorghum and sweet potato on the bioavailability of iron, gene expression of proteins involved in iron metabolism and the plasma antioxidant capacity in animals fed with whole sorghum grains processed by dry heat or extrusion, combined or not with sweet potato flour with high content of carotenoids. Five experimental groups were tested (n = 7): dry heat sorghum flour (DS); extruded sorghum flour (ES); whole sorghum flour + sweet potato flour (DS + SP); extruded sorghum flour + sweet potato flour (ES + SP) and positive control (FS). The evaluations included: hemoglobin gain, hemoglobin regeneration efficiency, gene expression of divalente metal transporter 1 (DMT-1), duodenal citochroma B (DcytB), ferroportin, hephaestin, transferrin and ferritin and total plasma antioxidant capacity (TAC). The ES + SP group showed higher (p < 0.05) expression of DcytB, ferroportin and hephaestin when compared to the control group. The DS group showed high (p < 0.05) expression of DMT-1 and the ES showed high mRNA expression of transferrin and ferritin. The changes in the sorghum physicochemical properties from extrusion process reduced the iron and phytate content, and increased the gene expression of proteins involved in iron metabolism, improving iron bioavailability. The combination of sweet potato and sorghum flour (dry or extruded) improved the iron capture and total antioxidant capacity, probably due to the presence of β-carotene and antioxidant compounds.     

Quinoa (Chenopodium quinoa Willd.) protein hydrolysates with in vitro dipeptidyl peptidase IV (DPP-IV) inhibitory and antioxidant properties

The potential of quinoa to act as a source of dipeptidyl peptidase IV (DPP-IV) inhibitory and antioxidant peptides was studied. A quinoa protein isolate (QPI) with a purity of 40.73 ± 0.90% was prepared. The QPI was hydrolysed at 50 °C for 3 h with two enzyme preparations: papain (P) and a microbial papain-like enzyme (PL) to yield quinoa protein hydrolysates (QPHs). The hydrolysates were evaluated for their DPP-IV inhibitory and oxygen radical absorbance capacity (ORAC) activities. Protein hydrolysis was observed in the QPI control, possibly due to the activity of quinoa endogenous proteinases. The QPI control had significantly higher DPP-IV half maximal inhibitory concentrations (IC₅₀) and lower ORAC values than QPH-P and QPH-PL (P < 0.05). Both QPH-P and QPH-PL had similar DPP-IV IC₅₀ and ORAC values. QPH-P had a DPP-IV IC₅₀ value of 0.88 ± 0.05 mg mL⁻¹ and an ORAC activity of 501.60 ± 77.34 μmol Trolox equivalent (T.E.) g⁻¹. To our understanding, this is the first study demonstrating the in vitro DPP-IV inhibitory properties of quinoa protein hydrolysates. QPHs may have potential as functional ingredients with serum glucose lowering properties.     

Improved functional properties of pasta: Enrichment with amaranth seed flour and dried amaranth leaves

The present investigation evaluated the effects of dried amaranth leaves (DAL) and amaranth seed flour (AF) as ingredients for pasta production and their contribution to antioxidant activity. Cooking quality, proximal and aroma analysis, antioxidant capacity and sensory evaluations were performed. The results demonstrated that pastas with amaranth ingredients had decreased cooking time, increased cooking loss percentage, and decreased luminosity values compared with semolina control pasta. Pastas with both AF and DAL demonstrated the highest protein, crude fiber and ash contents. The addition of DAL resulted in higher contents of iron, zinc, magnesium and potassium compared with the control pasta. TC, FRAP and ORAC assays showed that the pastas exhibited an important reduction in antioxidant capacity by cooking process. Formulas with DAL showed the higher antioxidant capacity values after cooking. The addition of AF and DAL has proved to increase the functional benefits of the pasta.     

Dough rheological properties and noodle-making performance of non-waxy and waxy whole-wheat flour blends

Dough rheological properties and noodle-making performance of non-waxy whole-wheat flour (WWF) with partial- or full-waxy (PW- or FW-) WWF substitution were studied. The substitution levels were 0, 250, 500, 750, and 1000 g/kg, respectively. FW-WWF reduced the peak viscosity and pasting temperature of WWF blends as its substitution level was increased due to its higher proportions of B-type starch granules and short amylopectin chains, while PW-WWF increased peak viscosity with the increasing substitution level because of its higher amylopectin content. As demonstrated by farinograph and rheometer measurements, FW-WWF interfered with gluten development because of the increased competition for water by arabinoxylans and amylopectin; however, PW-WWF enhanced dough strength due primarily to its increased protein content. Consequently, FW-WWF showed a detrimental effect on cooked noodle texture as the cooked noodle hardness was reduced by 50% at the 1000 g/kg substitution level. In contrast, PW-WWF enhanced noodle integrity and elasticity by increasing cooked noodle cohesiveness and resilience by 10.1% and 14.8%, respectively, at the 1000 g/kg substitution level. The results suggest that with waxy WWF substitution, the changes in starch composition, arabinoxylans, and protein content could modify the interactions among flour components and influence the quality characteristics of noodle products.     

Vitreosity,its stability and relationship to protein content in durum wheat

High quality requirements are set on durum wheat (Triticum durum) from semolina mills and pasta producers. For the production of semolina and pasta with good cooking quality, high grain protein content and vitreosity is required. The dependency of vitreosity on protein content as well as its stability under the influence of humidity was not well investigated up to now. We (1) compared two methods to determine vitreosity, (2) investigated the relationship between vitreosity and protein content, (3) developed a method to analyze vitreosity under humidity, and (4) examined the relationship between protein content and agronomical as well as quality traits in durum wheat. The results showed that the formation of vitreous kernels greatly depends on the protein content. To evaluate the stability of vitreosity under the influence of humidity a new method was elaborated and employed to assess the durum germplasm under study. This revealed that vitreosity of a durum wheat variety depends on the potential to form vitreous kernels but also to maintain this vitreosity under the influence of humidity. Our results further show that protein content is a central trait in durum wheat that strongly influences important traits like grain yield, vitreosity, and b-value.     

Effects of the invasive tomato red spider mite (Acari: Tetranychidae) on growth and leaf yield of African nightshades

The tomato red spider mite, Tetranychus evansi Baker and Pritchard, is one of the most serious pests of solanaceous crops in Africa. Field experiments were conducted to investigate its effects on the growth and leaf yield of five African nightshade species viz. Solanum americanum, S. sarrachoides, S. scabrum, S. tarderemotum and S. villosum during the 2008 and 2009 growing seasons. Plants were infested with 2–4 day-old female spider mites which were allowed to multiply. The number of mite motiles increased throughout the growing season in unsprayed plots and this number varied significantly between the African nightshade species. Except for S. sarrachoides, leaf damage was high on the other four Solanum species irrespective of the spraying regime during both seasons. However, S. scabrum had a significantly greater leaf area ratio (ratio of leaf area to total plant weight) and specific leaf area (ratio of leaf area to total leaf dry weight) during both seasons. Overall yields were 1.5 times more in S. scabrum and S. sarrachoides compared to S. americanum, S. tarderemotum and S. villosum. Our results show that T. evansi infestation affects the leaf area ratio and specific leaf area of African nightshade species differentially which eventually determines the plant's overall leaf yield. These findings present an opportunity for evaluation and selection of African nightshade species that can withstand spider mite infestation in small holder farms for increased vegetable production in Africa.     

Distribution of bioactive compounds in maize fractions obtained in two different types of large scale milling processes

Maize kernels contain different bioactive compounds that are important for human health. The aim of this study was to analyze the distribution of the bioactive compounds in maize fractions derived from two industrial dry-milling processes, characterized by a dry-degermination (DD) system and a tempering-degermination (TD) system.The bioactive compounds in maize resulted unevenly distributed in the milling fractions of the kernel. By-products such as the germ and the animal feed flour, had higher total antioxidant capacity (TAC), total polyphenol content (TPC) and total dietary fibre content (TDF) than the whole grains, while xanthophyll and resistant starch resulted to be higher in the fractions derived from the vitreous endosperm. The germ fraction showed also the highest folate content. Results also showed that the type of degermination process influences the bioactive compound contents in the milling fraction, in accordance to the effectiveness of the germ and bran removal from the endosperm fractions. In particular, the animal feed flour obtained by means of TD system resulted in a higher TAC, TPC and TDF than the same fraction obtained by means of the DD system. Conversely, the extraction rate do not affect the recovery of bioactive components in particular fractions.     

Influence of the cultivar,environment and management on the grain yield and bread-making quality in winter wheat

The genotype, environment and their interaction play an important role in the grain yielding and grain quality attributes. The main aim of this study was to determine the contributions of the genotype, environment and their interaction to the variation in bread-making traits. The data that were used for the analyses performed in this study were obtained from 3 locations in Poland from post-registration multi-environment trials with winter wheat in 2009 and 2010. The experimental factors were the cultivar (7 cultivars) and the crop management level (low input and high input). In the multi-environment trials, 17 traits were investigated that characterize grain, flour and dough quality. Most of the traits were affected much more strongly by environmental factors (i.e., year and location) than by genotype. The variance components revealed an especially strong effect of the year on the baking score, loaf volume and water absorption, as well a strong effect of the location on dough development and protein content. The obtained results demonstrate that the grain quality as measured by the parameters based on the protein content and quality may be substantially improved by crop management practices, especially by N fertilization level.     

Enhancement of biocontrol efficacy of Pichia membranaefaciens by hot water treatment in postharvest diseases of citrus fruit

Effects of hot water treatment (HWT; 53 °C for 2 min) and Pichia membranaefaciens, either alone or in combination, on controlling Penicillium italicum, Penicillium digitatum, and natural infection in citrus fruit were investigated. Results showed that the combined treatment significantly reduced disease incidence and lesion diameters of blue and green molds in artificially inoculated fruit whether the pathogens were inoculated after or before the treatment compared with the treatment of P. membranaefaciens or HWT alone. The combination of P. membranaefaciens with HWT was as effective as the fungicide treatment in natural infection trials. Application of HWT did not affect the growth of P. membranaefaciens in the wounds of citrus fruit at 20 °C or 4 °C. P. membranaefaciens combined with HWT effectively enhanced the phenylalanine ammonia-lyase, peroxidase, polyphenoloxidase, chitinase, and β-1,3-glucanase activities and stimulated the synthesis of phenolic compounds. These results suggest that the use of HWT is a useful approach to improve the efficacy of P. membranaefaciens in postharvest diseases of citrus fruit.     

Whole wheat bread: Effect of bran fractions on dough and end-product quality

Consumption of whole-wheat based products is encouraged due to their important nutritional elements that benefit human health. However, the use of whole-wheat flour is limited because of the poor processing and end-product quality. Bran was postulated as the major problem in whole wheat breadmaking. In this study, four major bran components including lipids, extractable phenolics (EP), hydrolysable phenolics (HP), and fiber were evaluated for their specific functionality in flour, dough and bread baking. The experiment was done by reconstitution approach using the 2⁴ factorial experimental layout. Fiber was identified as a main component to have highly significant (P < 0.05) and negative influence on most breadmaking characteristics. Although HP had positive effect on farinograph stability, it was identified as another main factor that negatively impacted the oven spring and bread loaf volume. Bran oil and EP seemed to be detrimental to most breadmaking characteristics. Overall, statistical analysis indicates that influence of the four bran components are highly complex. The bran components demonstrate multi-way interactions in regards to their influence on dough and bread-making characteristics. Particularly, Fiber appeared to have a high degree of interaction with other bran components and notably influenced the functionality of those components in whole wheat bread-making.     

Immunomodulatory activities of non-prolamin proteins in wheat germ and gluten

Albumin (Alb), globulin (Glo), glutelin (Gll) and glutenin (Gln) were separately extracted from wheat germ and wheat gluten. Amino acisd composition, molecular weight distribution, solubility, in vitro digestibility, and immunomodulatory activities were all analyzed. Gll and Gln have similar molecular weight distributions, which differed from those of Alb and Glo. Alb showed the highest solubility at various pH values (except pH 4.0), whereas Glo showed the highest in vitro digestibility. Glo and Gll have the highest proportion of essential to total amino acids, while Alb and Gll have the highest protein digestibility-corrected amino acid scores. Gll had the strongest immunomodulatory effects in terms of stimulation of RAW 264.7 cells to produce IL-6, TNF-α, and IL-10, and good stimulatory effects on splenocyte proliferation, production of IL-2, phagocytosis, and secretion of nitric oxide in RAW 264.7 cells. Gll can be considered a good protein source for use in health foods.