The Chinese bread wheat cultivar Xiaoyanmai 7 harbours genes encoding a pair of novel high-molecular-weight glutenin subunits inherited from cereal rye

The high-molecular-weight glutenin subunits (HMW-GS) represent a major component of the endosperm storage protein in the grains of wheat and its related species. Their technological importance results from their ready formation of intermolecular disulfide bonds, which underlie much of the visco-elasticity displayed by gluten and hence the processing quality of the flour. Here, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis revealed that the Chinese wheat cultivar Xiaoyanmai 7 formed four distinct HMW-GS, two of which are likely the product of a known allele at the Glu-B1 locus, whereas the other two did not match any known HMW-GS. A combined analysis based on reversed-phase high-performance liquid chromatography (RP-HPLC), N-terminal sequencing and mass spectrometry confirmed that the two novel proteins were genuine HMW-GS. Inspection of the DNA sequences showed that one of the novel HMW-GS was encoded by an x-type and the other by a y-type secalin gene. A karyotypic analysis confirmed that six of the seven pairs of Xiaoyanmai 7’s D genome chromosomes (the exception was chromosome 2D) had been replaced by rye chromosomes. The y-type HMW secalin present in Xiaoyanmai 7 differed from the standard By and Dy HWM-GS by the presence of an additional cysteine residue in its C-terminal domain.

Relationships between the HMW- and LMW-glutenin subunits and SDS-sedimentation volume in Spanish hulled wheat lines

Emmer and spelt are two hulled wheats that were widely grown in Spain until the latter 1960s. Twenty-nine emmer and twenty-six spelt lines obtained from Spanish accessions of these hulled wheats were analysed for quality traits and endosperm storage protein composition. The results showed a wide range of variability in these traits. Likewise, a certain association between some alleles of these proteins and the SDS-sedimentation volume has been detected.

Centric fusion between nonhomologous rye chromosomes in wheat

The frequency of centric fusion has been compared in three wheat–rye double monosomic addition lines. In one plant, designated plant A, both monosomes were bibrachial. In the second plant, B, one monosome was bibrachial and one telocentric. In the remaining plant, C, both monosomes were telocentric. Rye centric fusion chromosomes were identified in the progeny by C-banding mitotic root-tip chromosomes and electrophoresis of endosperm storage protein. Four of 97 analyzed progeny of plant A and 4 of 96 analyzed progeny of plant B possessed centric fusion chromosomes. In contrast, none of the 492 progeny of plant C possessed centric fusion chromosomes. The data indicate that at least one bibrachial monosome is necessary for the efficient production of centric fusion chromosomes.Key words: centric fusion, centromeric misdivision, monosomes.

Seed development in Ricinus communis cv. Hale (castor bean). III. Pattern of storage protein and phytin accumulation in the endosperm

The development of the endosperm of castor bean seed from its initial free nuclear state through to the end of maturation is presented. An investigation of the pattern of reserve accumulation in the endosperm at the light microscopy level revealed that the accumulation of soluble and insoluble storage proteins, and of phytin, does not occur simultaneously in all cells of the developing storage organ. Rates of reserve accumulation also vary among regions of the endosperm. Storage protein and phytin accumulation are initiated in a region midway between the periphery and central lumen of the endosperm by the early cotyledon stage of seed development. Afterwards, reserve deposition occurs more intensely in the proximal and more peripheral regions than in the distal and internal regions. A wave of reserve accumulation, or protein body maturation, proceeds from the more peripheral and the proximal regions to the more internal and distal regions as development continues. The last cells to complete reserve deposition are those in regions lying close to the endosperm lumen (into which the cotyledons have expanded) and the outermost two cell layers of the endosperm.