Wheat Endosperm Research Articles

The lycopene β-cyclase plays a significant role in provitamin A biosynthesis in wheat endosperm.

BackgroundLycopene β-cyclase (LCYB) is a key enzyme catalyzing the biosynthesis of β-carotene, the main source of provitamin A. However, there is no documented research about this key cyclase gene’s function and relationship with β-carotene content in wheat. Therefore, the objectives of this study were to clone TaLCYB and characterize its function and relationship with β-carotene biosynthesis in wheat grains. We also aimed to obtain more information about the endogenous carotenoid biosynthetic pathway and thus provide experimental support for carotenoid metabolic engineering in wheat.ResultsIn the present study, a lycopene β-cyclase gene, designated TaLCYB, was cloned from the hexaploid wheat cultivar Chinese Spring. The cyclization activity of the encoded protein was demonstrated by heterologous complementation analysis. The TaLCYB gene was expressed differentially in different tissues of wheat. Although TaLCYB had a higher expression level in the later stages of grain development, the β-carotene content still showed a decreasing tendency. The expression of TaLCYB in leaves was dramatically induced by strong light and the β-carotene content variation corresponded with changes of TaLCYB expression. A post-transcriptional gene silencing strategy was used to down-regulate the expression of TaLCYB in transgenic wheat, resulting in a decrease in the content of β-carotene and lutein, accompanied by the accumulation of lycopene to partly compensate for the total carotenoid content. In addition, changes in TaLCYB expression also affected the expression of several endogenous carotenogenic genes to varying degrees.ConclusionOur results suggest that TaLCYB is a genuine lycopene cyclase gene and plays a crucial role in β-carotene biosynthesis in wheat. Our attempt to silence it not only contributes to elucidating the mechanism of carotenoid accumulation in wheat but may also help in breeding wheat varieties with high provitamin A content through RNA interference (RNAi) to block specific carotenogenic genes in the wheat endosperm.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-015-0514-5) contains supplementary material, which is available to authorized users.

Evaluation of iron and zinc in grain and grain fractions of hexaploid wheat and its related species for possible utilization in wheat biofortification

Iron (Fe) and zinc (Zn) contents in hexaploid wheat are very low and are further reduced because of the removal of micronutrient-rich bran of wheat grains during milling and processing. Therefore, hexaploid wheat, its wild species and wheat–Aegilops kotschyi substitution lines were evaluated to identify the genome(s) carrying gene(s) for high Fe and Zn concentrations in bran and endosperm fractions of grains. It is reflected from the results that Triticum monococcum (acc. W463) may serve as a promising donor for biofortification of Fe, and Aegilops speltoides (acc. 3804) may serve as a promising donor for biofortification of Zn in the endosperm of cultivated wheat. Further, among the three wheat–Ae. kotschyi substitution lines, the higher concentration of Fe and Zn in endosperm fraction was observed in BC2F4 63-2-13-1. The work on precise transfer of useful gene(s) from 7Uk chromosome of this line is in progress to reduce linkage drag.

Reactive oxygen species regulate programmed cell death progress of endosperm in winter wheat (Triticum aestivum L.) under waterlogging.

Previous studies have proved that waterlogging stress accelerates the programmed cell death (PCD) progress of wheat endosperm cells. A highly waterlogging-tolerant wheat cultivar Hua 8 and a waterlogging susceptible wheat cultivar Hua 9 were treated with different waterlogging durations, and then, dynamic changes of reactive oxygen species (ROS), gene expressions, and activities of antioxidant enzymes in endosperm cells were detected. The accumulation of ROS increased considerably after 7 days of waterlogging treatment (7 DWT) and 12 DWT in both cultivars compared with control group (under non-waterlogged conditions), culminated at 12 DAF (days after flowering) and reduced hereafter. Waterlogging resulted in a great increase of H2O2 and O2 (-) in plasma membranes, cell walls, mitochondrias, and intercellular spaces with ultracytochemical localization. Moreover, the deformation and rupture of cytomembranes as well as the swelling and distortion of mitochondria were obvious. Under waterlogging treatment conditions, catalase (CAT) gene expression increased in endosperm of Hua 8 but activity decreased. In addition, Mn superoxide dismutase (MnSOD) gene expression and superoxide dismutase (SOD) activity increased. Compared with Hua 8, both CAT, MnSOD gene expressions and CAT, SOD activities decreased in Hua 9. Moreover, ascorbic acid and mannitol relieve the intensifying of PCD processes in Hua 8 endosperm cells induced by waterlogging. These results indicate that ROS have important roles in the PCD of endosperm cells, the changes both CAT, MnSOD gene expressions and CAT, SOD activities directly affected the accumulation of ROS in two different wheat cultivars under waterlogging, ultimately led to the PCD acceleration of endosperm.

Comparative proteome analysis of embryo and endosperm reveals central differential expression proteins involved in wheat seed germination.

BackgroundWheat seeds provide a staple food and an important protein source for the world’s population. Seed germination is vital to wheat growth and development and directly affects grain yield and quality. In this study, we performed the first comparative proteomic analysis of wheat embryo and endosperm during seed germination.ResultsThe proteomic changes in embryo and endosperm during the four different seed germination stages of elite Chinese bread wheat cultivar Zhengmai 9023 were first investigated. In total, 74 and 34 differentially expressed protein (DEP) spots representing 63 and 26 unique proteins were identified in embryo and endosperm, respectively. Eight common DEP were present in both tissues, and 55 and 18 DEP were specific to embryo and endosperm, respectively. These identified DEP spots could be sorted into 13 functional groups, in which the main group was involved in different metabolism pathways, particularly in the reserves necessary for mobilization in preparation for seed germination. The DEPs from the embryo were mainly related to carbohydrate metabolism, proteometabolism, amino acid metabolism, nucleic acid metabolism, and stress-related proteins, whereas those from the endosperm were mainly involved in protein storage, carbohydrate metabolism, inhibitors, stress response, and protein synthesis. During seed germination, both embryo and endosperm had a basic pattern of oxygen consumption, so the proteins related to respiration and energy metabolism were up-regulated or down-regulated along with respiration of wheat seeds. When germination was complete, most storage proteins from the endosperm began to be mobilized, but only a small amount was degraded during germination. Transcription expression of six representative DEP genes at the mRNA level was consistent with their protein expression changes.ConclusionWheat seed germination is a complex process with imbibition, stirring, and germination stages, which involve a series of physiological, morphological, and proteomic changes. The first process is a rapid water uptake, in which the seed coat becomes softer and the physical state of storage materials change gradually. Then the germinated seed enters the second process (a plateau phase) and the third process (the embryonic axes elongation). Seed embryo and endosperm display distinct differentially expressed proteins, and their synergistic expression mechanisms provide a basis for the normal germination of wheat seeds.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-015-0471-z) contains supplementary material, which is available to authorized users.

Extractability and chromatographic characterization of wheat (triticum aestivum l.) bran protein.

About 70% of the protein for human consumption is derived from plants, with cereals as the most important source. Wheat bran protein has a more balanced amino acid profile than that of flour. We here for the first time report the amino acid, size exclusion, and SDS-PAGE profiles of bran Osborne protein fractions (OPFs). Moreover, we also investigated how OPFs are affected when physical barriers which entrap proteins in bran tissues are removed. Albumin/globulin is the most abundant OPF. It is richer in lysine and asparagine/aspartic acid than other OPF. Most bran albumin/globulin proteins have a molecular weight (MW) lower than 30 k and their chromatographic profiles differ from those of flour. The prolamin has high levels of proline and glutamine/glutamic acid. It is rich in proteins with a MW of 30 to 45 k and about 66 k reflecting contamination with gliadin from endosperm. The glutelin has high levels of glycine, proline, and glutamine/glutamic acid. Its protein is of intermediate and high MW with little protein with MW lower than 30 k. The high (MWs from 80 to 120 k) and low (MW around 45 k) MW glutenin subunits of flour are also present in bran. The glutelin of wheat endosperm is named glutenin. Ball milling releases albumin/globulin and glutelin but not prolamin. Not all glutelin was endosperm glutenin as a substantial part was entrapped in the aleurone cells.

Effect of 7H(ch) Hordeum chilense chromosome introgressions on the wheat endosperm proteomic profile.

Hordeum chilense is an excellent genetic resource for wheat breeding due to its potential to improve breadmaking quality and nutritional value and provide resistance to some biotic and abiotic stresses. Hexaploid wheat lines carrying chromosome 7H(ch) introgressions, namely, chromosome additions of the whole chromosome 7H(ch) or the 7H(ch)α or the 7H(ch)β chromosome arms, and chromosome substitutions of the homeologous chromosomes 7A, 7B, or 7D by chromosome 7H(ch) were compared by 2D-PAGE analysis to study the effect of these alien introgressions on the wheat endosperm proteome. The addition of the 7H(ch)α chromosome arm did not alter the profile of most glutenins and gliadins, but showed higher quantities of puroindolines and lower xylanase inhibitors, which might improve also resistance to plant pathogens. On the other hand, (7A)7H(ch) or (7D)7H(ch) substitution lines showed enhanced avenin-like b proteins and triticin levels but reduced puroindolines, which could be desirable to improve dough properties and nutritional value and increase kernel hardness in wheat.

Brewer’s spent grain: source of value-added polysaccharides for the food industry in reference to the health claims

Brewer’s spent grain (BSG) is the most abundant by-product of the brewing industry, constituting approximately 85 % (w/w) of the total by-products generated during beer production. Rich in cellulose and non-cellulosic polysaccharides, lignin, and proteins, BSG provides extra nutritional value, thereby arousing the interest of the food industry. Annually, around 3.4 million t of BSG are produced within the European Union, and Germany contributes approximately 2 million t. BSG is reused either substantial or energetic. However, its main application has been limited to animal feeding. Based on the intense global pressure toward green environmental technology and increasing regulations in the feed sector, alternative application fields have gained importance. Because of its high protein and fiber contents, BSG can be an attractive source for value-added products in human nutrition. The focus is on the reported health effects of (1–3,1–4)-β-d-glucan and arabinoxylan (AX). Several scientific studies have shown that barley (1–3,1–4)-β-d-glucan reduces blood cholesterol levels. A cause and effect relationship has been established between the consumption of AX from wheat endosperm and the reduction of postprandial glycemic responses. The intention of this review is to focus on the extraction of (1–3,1–4)-β-d-glucan and AX from BSG as a source of value-added compounds for use as a nutraceutical. In view of AX and (1–3,1–4)-β-d-glucan yield, different methods of extraction are presented. Finally, technological trends and future perspectives to expand this market are discussed, focusing on promising strategies such as the use of pressurized hot water extraction.

Response to comments on the Scientific Opinion of the EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA) on the scientific substantiation of a health claim related to “high fibre sourdough rye bread” and reduction of post‐prandial glycaemic responses pursuant to Article 13(5) of Regulation (EC) No 1924/2006

EFSA Supporting PublicationsVolume 12, Issue 4 796E Technical reportOpen Access Response to comments on the Scientific Opinion of the EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA) on the scientific substantiation of a health claim related to “high fibre sourdough rye bread” and reduction of post-prandial glycaemic responses pursuant to Article 13(5) of Regulation (EC) No 1924/2006 European Food Safety Authority (EFSA), European Food Safety Authority (EFSA)Search for more papers by this author European Food Safety Authority (EFSA), European Food Safety Authority (EFSA)Search for more papers by this author First published: 17 April 2015 https://doi.org/10.2903/sp.efsa.2015.EN-796 Published date: 17 April 2015 Question number: EFSA-Q-2015-00014 AboutPDF ToolsExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat References Atkinson FS, Foster-Powell K and Brand-Miller JC, 2008. International tables of glycemic index and glycemic load values: 2008. Diabetes Care, 31, 2281– 2283. EFSA NDA Panel (EFSA Panel on Dietetic Products, Nutrition and Allergies), 2011a. General guidance for stakeholders on the evaluation of Article 13.1, 13.5 and 14 health claims. EFSA Journal 2011; 9(4):2135, 24 pp. doi:10.2903/j.efsa.2011.2135 EFSA NDA Panel (EFSA Panel on Dietetic Products, Nutrition and Allergies), 2011b. Scientific Opinion on the substantiation of health claims related to arabinoxylan produced from wheat endosperm and reduction of post-prandial glycaemic responses (ID 830) pursuant to Article 13(1) of Regulation (EC) No 1924/2006. EFSA Journal 2011; 9(6):2205, 15 pp. doi:10.2903/j.efsa.2011.2205 EFSA NDA Panel (EFSA Panel on Dietetic Products, Nutrition and Allergies), 2011c. Scientific Opinion on the substantiation of health claims related to beta-glucans from oats and barley and maintenance of normal blood LDL-cholesterol concentrations (ID 1236, 1299), increase in satiety leading to a reduction in energy intake (ID 851, 852), reduction of post-prandial glycaemic responses (ID 821, 824), and “digestive function” (ID 850) pursuant to Article 13(1) of Regulation (EC) No 1924/2006. EFSA Journal 2011; 9(6):2207, 21 pp. doi:10.2903/j.efsa.2011.2207 EFSA NDA Panel (EFSA Panel on Dietetic Products, Nutrition and Allergies), 2012a. Guidance on the scientific requirements for health claims related to appetite ratings, weight management, and blood glucose concentrations. EFSA Journal 2012; 10(3):2604, 11 pp. doi:10.2903/j.efsa.2012.2604 EFSA NDA Panel (EFSA Panel on Dietetic Products, Nutrition and Allergies), 2012b. Scientific Opinion on the substantiation of health claims related to alpha-cyclodextrin and reduction of post-prandial glycaemic responses (ID 2926, further assessment) pursuant to Article 13(1) of Regulation (EC) No 1924/2006. EFSA Journal 2012; 10(6):2713, 17 pp. doi:10.2903/j.efsa.2012.2713 EFSA NDA Panel (EFSA Panel on Dietetic Products, Nutrition and Allergies), 2014. Scientific Opinion on the substantiation of a health claim related to high-fibre sourdough rye bread and reduction of post-prandial glycaemic responses pursuant to Article 13(5) of Regulation (EC) No 1924/2006. EFSA Journal 2014; 12(10):3837, 11 pp. doi:10.2903/j.efsa.2014.3837 Volume12, Issue4April 2015796E ReferencesRelatedInformation

Aroma of wheat porridge and bread-crumb is influenced by the wheat variety

Sensory evaluations were conducted on wheat-flour porridge and baked-bread samples, made from wheat varieties with known odour and flavour variations. The purpose was to determine if these odour and flavour variations were expressed in baked-bread. In all, 24 wheat varieties were used for porridge evaluation, from these eight were selected for bread evaluation. Porridge and bread results were compared. Variations were found in both evaluations. Five odour- and nine flavour descriptors were found to be common to both wheat porridge and bread. The results for two descriptors: “cocoa” and “oat porridge” were correlated between the wheat porridge and bread samples. Analysis of whole-meal and low-extraction samples revealed that the descriptors “malt”, “oat-porridge”, “øllebrød”, “cocoa” and “grain” mostly characterized wheat bran, while descriptors for “maize”, “bean-shoots”, “chamomile”, “umami”, and “fresh grass” mostly characterized wheat endosperm. Low-extraction bread made from four different varieties also differentiated for five odour- and six flavour descriptors. These results indicate that variations in wheat flavour and odour directly affect bread flavour and odour even in low-extraction bread. This knowledge is important to the baking industry and to plant breeders as wheat aroma could possibly become a future quality parameter in breeding.

Effect of suppression of arabinoxylan synthetic genes in wheat endosperm on chain length of arabinoxylan and extract viscosity.

SummaryArabinoxylan (AX) is the dominant component within wheat (Triticum aestivum L.) endosperm cell walls, accounting for 70% of the polysaccharide. The viscosity of aqueous extracts from wheat grain is a key trait influencing the processing for various end uses, and this is largely determined by the properties of endosperm AX. We have previously shown dramatic effects on endosperm AX in transgenic wheat by down‐regulating either TaGT43_2 or TaGT47_2 genes (orthologues to IRX9 and IRX10 in Arabidopsis, respectively) implicated in AX chain extension and the TaXAT1 gene responsible for monosubstitution by 3‐linked arabinose. Here, we use these transgenic lines to investigate the relationship between amounts of AX in soluble and insoluble fractions, the chain‐length distribution of these measured by intrinsic viscosity and the overall effect on extract viscosity. In transgenic lines expressing either the TaGT43_2 or TaGT47_2 RNAi transgenes, the intrinsic viscosities of water‐extractable (WE‐AX) and of a water‐insoluble alkaline‐extracted fraction (AE‐AX) were decreased by between 10% and 50% compared to control lines. In TaXAT1 RNAi lines, there was a 15% decrease in intrinsic viscosity of WE‐AX but no consistent effect on that of AE‐AX. All transgenic lines showed decreases in extract viscosity with larger effects in TaGT43_2 and TaGT47_2 RNAi lines (by up to sixfold) than in TaXAT1 RNAi lines (by twofold). These effects were explained by the decreases in amount and chain length of WE‐AX, with decreases in amount having the greater influence. Extract viscosity from wheat grain can therefore be greatly decreased by suppression of single gene targets.

Observation and comparison of structure changes in wheat caryopsis maternal tissues and endosperm

During the caryopsis development, maternal tissues provide protection and nutrients for the endosperm. Wheat caryopses were observed using different microscopies to investigate structure characteristics of wheat caryopsis maternal tissues and endosperm. The results were as the following: (1) Maternal tissues, especially nucellar cells and pericarp parenchyma cells, degenerated to supply space to the endosperm growth. A thick cuticle layer adhered to the outer integument existed till the endosperm matured. The thick cuticle layer not only made sure that nutrients from the vascular system got into the endosperm through the chalaza but also was probably the key reason why integuments could affect the endosperm growth. (2) The green pericarp contained chloroplasts and perhaps played an important part in nursing other maternal tissues and limiting nutrients from phloem to be transported toward pericarp parenchyma cells. (3) Sieve tubes of the vascular system increased in response to the enhanced endosperm sink strength. Chalazal cell walls and inclusions probably changed to regulate the flux of nutrients transported into the endosperm. In one word, structure changes of maternal transport tissues had a close relationship with the endosperm development.

Effect of Allelic Variation in Triticin on Bread- and Chapati-Making Qualities of Wheat (Triticum aestivum)

Triticin, a legumin-like storage protein of wheat endosperm, was discovered nearly three decades ago but so far there is no report on its effect on the processing quality of wheat that is thought to be determined primarily by prolamins, its major seed storage proteins. To investigate the effect of different classes of seed proteins on wheat quality using a genetic reconstitution approach, we produced 31 near-isogenic lines (NILs) with different alleles of triticin, high molecular weight glutenin subunits (HMW-GS), low molecular weight glutenin subunits (LMW-GS), gliadins and albumins in a common genetic background of wheat variety HD2329 and analysed different quality parameters over a period of 4 years. The NILs did not differ in their flour protein content, but showed significant differences in SDS-sedimentation volume, Farinograph dough stability, bread loaf volume and chapati quality score. Main focus was on triticin for which two NILs with alleles Tri-A1a and Tri-D1a derived from a high-quality Indian wheat variety K68 were analysed. Positive effects of these triticin alleles on dough physical properties, bread loaf volume and chapatti quality score were quite large, comparable to the widely known effect of HMW-GS 5 + 10. Specific alleles of HMW-GS, Glu-A1a (subunit 1), Glu-B1b (subunits 7 + 8), Glu-B1i (subunits 17 + 18) and Glu-D1d (subunits 5 + 10) showed strong positive effects, whereas null allele Glu-A1c showed negative effect on the quality of recipient variety HD2329. Similarly, different alleles of LMW-GS showed varying effects with Glu-A3d, Glu-A3e and Glu-D5a showing positive effects, Glu-A3c showing negative effect and Glu-A3a showing no significant effect. Gliadin alleles generally showed negative effects, whereas albumins showed no significant effect. While results with glutenin and gliadin alleles were as expected, we show here for the first time a significant effect of triticin on the wheat flour quality, suggesting that end-use quality of wheat varieties can be improved by combining specific alleles of triticin.

Comparison of Endosperm Starch Granule Development and Physicochemical Properties of Starches from Waxy and Non-Waxy Wheat

Starch granule development and physicochemical properties of starches in waxy wheat and non-waxy wheat were investigated in this article. Starch granules in waxy wheat endosperm showed an early developmental process. Compared with non-waxy wheat starch granules (round-shaped), waxy wheat starch granules (ellipse-shaped) were larger and contained more B-type granules. According to the granule size, starch granules were divided into two groups in waxy wheat, but were divided into three groups in non-waxy wheat. Compared with non-waxy wheat starch, waxy wheat starch had higher swelling power, gelatinization temperatures (To, Tp, Tc), and relative degree of crystallinity. They showed similar ordered structures on external regions of starch granules. Additionally, waxy wheat starch had a higher proportion of double-helical components and a lower proportion of single-helical components than non-waxy wheat starch. Based on the previous results, it was concluded: (1) waxy wheat and non-waxy wheat not only differed in starch granule development, but also in physicochemical properties of starches; (2) waxy wheat had more potential value for producing traditional products than non-waxy wheat.

Concentration and shear rate dependence of solution viscosity for arabinoxylans from different sources

Arabinoxylans are cell wall polysaccharides abundant in plants. Alkaline extraction is commonly used to isolate arabinoxylans from cell wall rich materials, such as cereal brans, crop residues etc. While arabinoxylans from certain sources such as wheat endosperm, corn bran and rye bran have been widely studied, there is a lack of studies focusing on the rheological and molecular properties of arabinoxylans from a wide variety of different sources. In this study, we report the concentration and shear rate dependence of solution viscosity of alkali extractable arabinoxylans from seven different sources. All the polymers are found to show Newtonian flow behavior, particularly at low concentrations, which is considered unusual in high molecular weight polysaccharides. The concentration dependence data shows the presence of a single critical concentration, suggestive of random coil conformation, while the rate of viscosity change in the two regimes suggests a more rigid conformation. This seemingly contradictory behavior is explained on the basis of a semi-flexible conformation of arabinoxylans in solution, which has been reported previously. The critical concentration of the arabinoxylans showed a strong correlation with their molecular weight, thus suggesting that fine structural differences do not significantly affect this aspect of rheological behavior. This is the first comparative study of alkali soluble arabinoxylans from different sources, and suggests that this class of polymers has significant similarities in spite of heterogeneity of fine structure.

Effect of semolina-jaggery diet on survival and development of Drosophila melanogaster

Drosophila melanogaster is an ideal model organism for developmental studies. This study tests the potential of semolina-jaggery (SJ) diet as a new formulation for bulk rearing of flies. Semolina and jaggery are organic products obtained from wheat endosperm and cane sugar, respectively. Semolina is a rich source of carbohydrates and protein. Jaggery has a high content of dietary sugars. Moreover, preparation of semolina jaggery diet is cost-effective and easy. Thus, the current study aimed to compare survival and developmental parameters of flies fed the SJ diet to flies fed the standard cornmeal-sugar-yeast (CSY) diet. SJ diet enhanced survival of flies without affecting fecundity; male flies showed increased resistance to starvation. A higher number of flies emerged at F2 and F3 generation when fed the SJ diet than when fed the control CSY diet. SJ diet did not increase fly body weight and lipid percentage. Therefore, SJ diet can be used for bulk rearing of healthy flies at par with the standard cornmeal-sugar-yeast diet.

Dynamics of phosphorus compounds in ripening and germinating cereal grains. Part II. Changes in phosphorus compounds content during germination of wheat, barley and rye grains

The dynamics of phosphorus compounds was investigated in the embryos and endosperm of wheat (Grana), barley (Kosmos) and rye (Pancerne) grain after 2, 4 and 6 days of germination. In germinating grain the phosphorus compounds transformations ran along the way of synthesis in the embryo and of breakdown in the endosperm. The level of phosphorus: inorganic, nucleotides, saccharides esters and their metabolites, lipid, RNA, DNA, phytin free and phytin bound with proteins and proteins rapidly increased in germinating seed embryos. The content of phosphorus free phytin and that bound with proteins, lipids, RNA and DNA in the endosperm rapidly decreased during germination. On the other hand, the saccharides phosphorus and that of their metabolites did not change, and inorganic, nuclotides and proteins-P slightly increased. Germinating rye grains showed a higher rate of synthesis in the embryos and of breakdown in the endosperm of the investigated phosphorus compounds than wheat and barley grains.

Lutein esterification in wheat endosperm is controlled by the homoeologous group 7, and is increased by the simultaneous presence of chromosomes 7D and 7Hch from Hordeum chilense

The high carotenoid content in tritordeum (×Tritordeum Ascherson et Graebner) grains is derived from its wild parent, Hordeum chilense Roem. et Schulz. Phytoene synthase 1 (Psy1) is located on chromosome 7HchS and plays a major role in this trait. This study investigates the impact of the introgression of chromosome 7Hch into common wheat background on carotenoid composition, including xanthophylls esterified with fatty acids (monoesters and diesters). All of the genetic stocks carrying Psy1 from H. chilense increased their carotenoid content relative to common wheat. In addition, significant changes in the carotenoid profile were detected in different genetic stocks. The most relevant was the increase in content of lutein diesters when both 7Hch and 7D were present, which indicates the existence of genes involved in the esterification of xanthophylls in both chromosomes. Furthermore, our results suggest that 7Hch genes preferentially esterify lutein with palmitic acid, whereas 7D is either indifferent to the fatty acid or it prefers linoleic acid for lutein esterification. The involvement and complementarity of 7Hch and 7D are highly significant considering the scarcity of previous results on lutein esterification in wheat.

Ribonucleic acids of wheat grain and its endosperm during development and ripening

The work present quantitative changes and synthesis od: RNA fractions in wheat grain and endosperm during development and ripening. It was found that share of rRNA in total RNA decreases during development both, in the endosperm and in grain. Rapid drop of rRNA content in total RNA takes place in the endosperm since 31st day after blooming, and in grain - since 45th day after blooming. Absolute amount of rRNA, as calculated per 100 grains or endosperms, increases in the first half of grain formation period, and then decreases till the end of development. As a result of degradation of ribosomal RNA in endosperm, low-molecule fraction – 4 S, significantly increased at final stage of development. Decrease of rRNA fraction at final stage of development is not accompanied by an increase of absolute amount of 4 S RNA fraction. Incorporation of 3H-,uriidine into grain and endosperm RNA is highest at the begining of development. Further on it gradually decreases till the end of development. Synthesis of RNA in grain takes place throughout the whole development. Contrary to this, no incorporation of precursor into rRNA was noted during waxy and full ripeness of wheat grain.

Allelic variation inGlu-1andGlu-3loci of bread wheat (Triticum aestivumssp.aestivumL. em. Thell.) germplasm cultivated in Algeria

Wheat endosperm storage proteins are the major components of gluten. They play an important role in dough properties and in bread making quality in various wheat varieties. In the present study, the different alleles encoded at the 6 glutenin loci were identified from a set of 71 hexaploid wheat germplasm cultivated in Algeria using SDS-PAGE. At Glu-A1, Glu-B1 and Glu-D1, encoding high molecular weight glutenin subunits (HMW-GS), 3, 6 and 5 alleles were observed, respectively. Low molecular weight glutenin subunits (LMW-GS) displayed similar polymorphism, as 4, 9 and 3 alleles were identified at loci Glu-A3, Glu-B3 and Glu-D3, respectively. A total of 52 patterns resulted from the genetic combination of the alleles encoding at the six glutenin loci. This led to a significantly higher Nei coefficient of genetic variation in Glu-1 and Glu-3 loci (0.54). The Algerian hexaploid wheats exhibited allelic variation in HMW and LMW glutenin subunit composition and the variation differed from that of hexaploid wheats of other countries. The presence of high quality alleles in glutenin loci have led the Algerian wheat cultivars to be considered as an asset in breeding programs aimed for wheat quality.

Molecular Structure and Organization of Starch Granules from Developing Wheat Endosperm

ABSTRACTWheat starches isolated from seeds harvested between 7 and 49 days after anthesis (DAA) were fractionated into large (>8 μm) and small (<8 μm) granules and studied for starch structure and architecture. Starch granules at 7 DAA possessed unimodal size distribution, whereas it was bimodal at later maturity stages. The apparent amylose fraction of starch granules at early maturity (7 and 14 DAA) consisted of intermediate‐type materials, whereas starch at later maturity stages (28 and 49 DAA) contained branched amylose. Wide‐angle X‐ray scattering (WAXS) revealed a well‐developed polymorphic structure already at 7 DAA. Although the presence of a small proportion of B‐type crystallites mixed with A‐type crystallites was observed in the X‐ray diffractogram of starches at early maturation (7 and 14 DAA), it was masked by the A‐type crystallites at later maturity stages. However, the large granules had a higher proportion of B‐type crystallites and lower relative crystallinity (RC) than their small‐granule counterpart. The iodine absorption properties of the starch granules demonstrated different levels of mobility of the starch polymers at different stages of maturity and the mobility of more glucan polymers in the large granule population compared with the small granules at the same maturity stage. Iodine did not change the characteristic A‐type crystalline pattern of starch, but it increased RC. Changes in peak width at half height based on WAXS data further suggested the possible interaction of iodine with amylopectin intercluster chain segments and branch chains in formation of inclusion complexes.