Chromosomal control of wheat endosperm proteins. A critical review.

Progress made in the chromosomal location of structural genes for wheat endosperm proteins, and in the study of the regulation and quantitative expression of these genes, by using aneuploids and by related techniques, is critically evaluated. Recommendations for future work are proposed

Protein quality in cereals. Nutritional versus genetical factors

It is a well known fact that, although an increasing agricultural production has succesfully met the equally increasing caloric demand of mankind, the closing of the so called protein gap is becoming more difficult to solve every day. Plant breeders and plant nutritionists alike have become aware of the urgent need to include protein quantity and quality alongside crop yield as their high priority objectives. Cereal grains have been and will continué to be for some time the main protein source for most of the world. Genetic and nutritional methods to increase and improve cereal protein are therefore of great importance in modern agriculture. The purpose of this paper is to discuss current ideas about the interplay of genetic and nutritional factors affecting cereal protein yield and quality. Although we will not restrict the discussion to our data and will include abundant data from many workers, a systematic review of the subject is beyond the scope of this contribution. Furthermore, mostly data from wheat will be used to support the discussion

Expression of homoeologous molecular systems in wheat alloploids

Allopolyploidy is widespread in the plant kingdom, where it has been of considerable evolutionary significance. Although the existence of heterotic interactions between the genomes that make up an alloploid have been generally assumed, the precise nature of these interactions has not been extensively investigated. Presently available evidence about metabolic integration of the wheat genomes is examined in search of new insights about the different modes of genome interaction. Although additive expression seems to be the case for many homoeologous systems, more complex patterns of integration have become evident. Examples of enzyme subunit complementation, gene compensation and other dosage effects, holoprotein completion, and complementation of metabolic pathways are discussed

Chromosomal assignment of genes controlling salt-soluble proteins (albumins and globulins) in wheat and related species

alt-soluble proteins from the endosperms of wheat, barley, and rye have been separated by nonequilibrium electrofocusing x electrophoresis. Genes encoding 14 of the 25 components observed in wheat have been unambiguously assigned to 10 different chromosomes (1B, 3B, 3D, 4A, 4D, 5B, 6B, 6D, 7B, 7D) by analysis of the compensated nulli-tetrasomic series. Five more wheat proteins seem to be controlled by group 2 chromosomes. Analysis of wheat-barley and wheat-rye addition lines has led to the location of genes for 6 out of 20 barley proteins in 4 different chromosomes (1H, 3H, 4H, 6H; 1H is homoeologous to group 7 chromosomes of wheat) and of genes for 5 out of 20 rye proteins in two different chromosomes (2R, 4R). The relationship between the proteins reported here and previously characterized ones is discussed

Molecular control of winter dormancy in establishment in trees

Dormancy is an adaptive mechanism that enables woody plants to survive the freezing temperatures of winter. This complex process is characterized by the cessation of meristem activity, which is accompanied by winter bud set, extensive metabolic remodelling, an acquired high tolerance to cold and, in deciduous trees, by leaf senescence and abscission. The induction of dormancy occurs in response to seasonal environmental signals. In most woody plants, shortening of the photoperiod induces growth cessation, bud set, and some degree of cold acclimation. The subsequent drop in temperature then leads to a greater tolerance to cold and leaf fall. Experimental evidence indicates that the phytochrome system plays an important role as a day length sensor, and it has been recently reported that in poplar (Populus tremula x tremuloides), the photoperiodic control of dormancy induction is driven by a molecular mechanism that shares components with the mechanism of the photoperiodic control of flowering time in Arabidopsis. In contrast, the effects of low temperatures are less well understood. Nonetheless, it has been established that the chestnut (Castanea sativa Mill.) circadian molecular clock is disrupted both during winter and in response to cold, with presumable consequences on the general physiology of the plant. However, there is no direct evidence so far for its role in dormancy regulatio

Morocco as a possible domestication center for barley: biochemical and agromorphological evidence.

The distribution of genetic variants of a group of low molecular weight, chloroform-methanol soluble proteins (CM proteins), among Moroccan and non-Moroccan accessions of Hordeum spontaneum and among selections from several Moroccan landraces of H. vulgare and cultivars of the same species with widespread European origin, suggests that domestication of barley might have taken place in Morocco. An agromorphological characterization of the H. spontaneum accessions further supports this hypothesis. The possible Moroccan origin of the French cultivar Hatif de Grignon and of several Spanish 6-rowed barleys is also presented

The CM-proteins from cereal endosperm: Immunochemical relationships

The CM-proteins, which are salt-soluble proteins that can be extracted with chloroform: methanol (2: 1, v/v), seem to be present in the endosperm of all the cereal species investigated. Antibodies raised against a mixture of the barley CM-proteins (A-H) cross-reacted with wheat and rye proteins in Ouchterlony tests and a detailed study was carried out for purified wheat (CM1, CM2. CM3. CM3') and barley (CMa, CMb, CMc, CMd) CM-proteins. [35Sl-Cysteine-labelled endosperm proteins from wheat and barley were investigated by immuno-precipitation, electrophoresis and fluorography using the antibodies (A-H) and also those to a mixture of wheat CM-proteins and to CMd. There was complete antigenic identity for all the wheat proteins and CMd, some of the other proteins showed partial antigenic identity. Previously proposed genetic and biochemical relationships among these proteins were confirmed in the present study

Identification of a homolog of Arabidopsis DSP4 (SEX4) in chestnut: its induction and accumulation in stem amyloplasts during winter or in response to the cold_

Oligosaccharide synthesis is an important cryoprotection strategy used by woody plants during winter dormancy. At the onset of autumn, starch stored in the stem and buds is broken down in response to the shorter days and lower temperatures resulting in the buildup of oligosaccharides. Given that the enzyme DSP4 is necessary for diurnal starch degradation in Arabidopsis leaves, this study was designed to address the role of DSP4 in this seasonal process in Castanea sativa Mill. The expression pattern of the CsDSP4 gene in cells of the chestnut stem was found to parallel starch catabolism. In this organ, DSP4 protein levels started to rise at the start of autumn and elevated levels persisted until the onset of spring. In addition, exposure of chestnut plantlets to 4 °C induced the expression of the CsDSP4 gene. In dormant trees or cold-stressed plantlets, the CsDSP4 protein was immunolocalized both in the amyloplast stroma and nucleus of stem cells, whereas in the conditions of vegetative growth, immunofluorescence was only detected in the nucleus. The studies indicate a potential role for DSP4 in starch degradation and cold acclimation following low temperature exposure during activity–dormancy transition

Two-dimensional electrophoresis as a tool for structural and genetic studies of seed proteins from Poaceae and Fagaceae.

The application of two-dimensional electrophoretic procedures to structural and genetic studies of seed proteins from Poaceae (including the cultivated cereals) and Fagaceae is described. The following related problems have been considered: covalent and non-covalent association of protein subunits in multiple oligomeric structures; chromosomal locations of genes encoding seed proteins; quantitation of gene products in relation to gene expression and regulation; purification of protein components to study their homology relationships and in vitro activities; evolutionary and phylogenetic relationships; identification of genetic stocks. Isoelectric focusing, pore-gradient electrophoresis, electrophoresis at different pH's, are among the separation procedures used in the first dimension, whereas sodium dodecyl sulfate-polyacrylamide gel electrophoresis and starch-gel electrophoresis at acid pH have been the preferred second-dimensional methods. Dissociating conditions (sodium dodecyl sulfate, Nonidet P-40, or urea) and reducing conditions (2-mercaptoethanol) have been used when require

Chromosomal location and expression of genes encoding low molecular weight proteins in wheat and related species

A review of recent work on the chromosomal location and expression of genes encoding moderately abundant, presumably non-storage endosperm proteins from wheat, barley and rye is presented. Related aspects, such as regulatory genetic effects, in vivo and in vitro synthesis, types of processing, deposition sites, and molecular cloning are also discussed. The relevance of these studies in connection with basic endosperm biology, genetic manipulation of quality and agronomic traits, and the evolution of these important crops is briefly emphasized