Genetic variability and improvement of seed proteins in wheat

Grain protein variability among species of Triticum and Aegilops: quantitative SDS-PAGE studies

Total proteins were extracted from degermed seeds of various species of Triticum and Aegilops with solutions containing sodium dodecyl sulfate (SDS) and mercaptoethanol. The reduced, dissociated proteins were fractionated according to molecular weight (MW) by high-resolution polyacrylamide gel electrophoresis in buffers containing SDS (SDS-PAGE). Stained SDS-PAGE patterns were measured by densitometric scanning over a suitable range of optical density. The data were normalized to equivalent total areas for each of the densitometric scans by means of a computer program that also permitted the construction of patterns of hypothetical amphiploids by averaging patterns of two or three diploid species. The grain proteins of most species examined had distinctive qualitative and quantitative aspects that were characteristic of the species even though nearly every accession or cultivar of a species exhibited at least minor differences in pattern from other accessions or cultivars. The main protein components (probably prolamins) of Triticum monococcum ssp. monococcum, T. monococcum ssp. boeoticum, T. urartu, and Aegilops squarrosa had MW's in the range 29-36 X 10(3) whereas the most important components of Ae. speltoides, Ae. longissima, and Ae. searsii had MW's in the range 37-55 × 10(3). Changes in the quantitative expression of particular genes, especially those coding for storage protein components, may have been associated with speciation. The strong predominance of proteins with MW's in the range 29-36 × 10(3) in some accessions of AB genome tetraploids, such as T. turgidum ssp. dicoccoides, may indicate contributions to the B genome of these tetraploids by T. monococcum ssp. boeoticum, T. urartu, or Ae. squarrosa.

Some features of the inheritance of avenins, the alcohol soluble proteins of oat

The inheritance of avenin components, the prolamins (or alcohol soluble proteins) of Avena, is studied by means of gel electrophoresis. Avenin is composed of rather similar proteins which appear as a polymorphic group from a biochemical point of view. After a first preliminary investigation it showed a surprisingly high interspecific variability. The average number of its constituents increases with the ploidy level but it still is much lower than that of wheat gliadin.The avenin electrophoretic patterns of 47 samples (F4, F5 or F6 seeds) resulting from 3 hexaploid crosses are compared with the parental patterns. Four kinds of inheritance are observed. Roughly 50% of progeny profiles are identical to those of one of the parents. They are composed occasionally of partial sections of parental patterns. Complete additiveness occurs rather seldom. However, in one of the crosses a significant number of progeny samples show a band, one of the very slow moving constituents, which was not present in either of the parents.The study of avenin in F1 seeds, arising from reciprocal crosses between two homozygous parent plants, shows a significant effect of maternal gene dose in the triploid endosperm.Because of both the variability and the relatively small number of avenin constituents, these results show that typical endosperm proteins such as oat prolamin constitute a useful tool for phylogenetic studies of the genus Avena.