Encoding genes for endosperm proteins in Hordeum chilense

Tritordeum as an Innovative Alternative to Wheat: A Comparative Digestion Study on Bread

Tritordeum results from the crossbreeding of a wild barley (Hordeum chilense) species with durum wheat (Triticum turgidum spp. turgidum). This hexaploid crop exhibits agronomic and rheological characteristics like soft wheat, resulting in an innovative raw material to produce baked goods. We applied a gel-based proteomic approach on refined flours to evaluate protein expression differences among two widespread tritordeum cultivars (Aucan and Bulel) taking as the reference semolina and flour derived from a durum and a soft wheat cvs, respectively. The products of in vitro digestion of model breads were analyzed to compare bio-accessibility of nutrients and mapping tritordeum bread resistant peptides. Significant differences among the protein profiles of the four flours were highlighted by electrophoresis. The amino acid bio-accessibility and the reducing sugars of tritordeum and wheat breads were comparable. Tritordeum cvs had about 15% higher alpha-amino nitrogen released at the end of the duodenal simulated digestion than soft wheat (p < 0.05). Bulel tritordeum flour, bread and digested bread had about 55% less R5-epitopes compared to the soft wheat. Differences in protein expression found between the two tritordeum cvs reflected in diverse digestion products and allergenic and celiacogenic potential of the duodenal peptides. Proteomic studies of a larger number of tritordeum cvs may be successful in selecting those with good agronomical performances and nutritional advantages.

Linkage relationships between prolamin genes located on chromosome 1Hch in Hordeum chilense

The endosperm storage proteins of Hordeum chilense Roem. et Schult., a species used in the synthesis of the amphiploid tritordeum (x Tritordeum Ascherson et Graebner), have a great effect on the gluten strength of this amphiploid. We have analysed electrophoretically the heredity of these proteins, which are synthesised by genes located on chromosome 1H(ch), and detected up to five loci in a cross between two lines of H. chilense. These loci present a certain homology with loci synthesising the same proteins in wheat. The genetic distances between these loci were calculated.

Physical mapping of repetitive DNA sequences and 5S and 18S-26S rDNA in five wild species of the genus Hordeum

The genetic relationships between several wild species and subspecies of the genus Hordeum were assessed using fluorescence in situ hybridization (FISH). Plant material included natural populations of wild barley growing in Spain of the annual species, H. marinum ssp. marinum (2n = 14) and gussoneanum (2n = 14), and H. murinum ssp. murinum (2n = 28), and leporinum (2n = 28) and the perennial species H. bulbosum (2n = 14) and H. secalinum (2n = 28), plus the South American perennial species H. chilense (2n = 14). FISH was used to locate the chromosomal sites of two rDNA multigene families 5S and 18S-26S (pTa71 and pTa794) and three repetitive DNA sequences (pSc119.2, pAs1 and pHch950) isolated from different species and genera. The seven chromosomes of the diploid species were readily distinguished by their external morphology and hybridization patterns to pTa71, pTa794, pSc119.2 and pAs1. These DNA probes were also useful for the identification of homologous chromosomes and in differentiating these from unidentified chromosomes in the tetraploid taxa. The use of the probe pHch950 permitted intergenomic differentiation in tetraploids and supports the diphyletic origin of H. murinum and H. secalinum. The in situ experiments yielded the following conclusions: (1) differences between the sub-species marinum and gussoneanum; (2) close relationships between the subspecies murinum and leporinum; and (3) major differences in physical mapping between H. bulbosum and the remaining taxa. The genomic and phylogenetic relationships between taxa, as inferred from the results, are discussed.

Isoelectric focusing in immobilized pH gradient of melon (Cucumis melo L.) seed protein: methodical and genetic aspects, and application in breeding

Genetic variability of melon seed proteins was studied by separation of seed protein by isoelectric focusing in immobilized pH gradient (IEF-IPG) under denaturing conditions. A routine procedure was developed for IEF-IPG of hundreds of individual melon seeds per day. A group of 74 accessions from 19 morphologically distinct groups and from different geographic origin were studied by IEF-IPG using pH gradients of 4-10, 4-7 and 6-10. The electrophoretic analysis of the 74 accessions showed 270 reproducible seed protein bands of which 70 were variable. Genetic evaluation led to the conclusion that at least 20 loci govern the variation found. The phylogenetic trees constructed using the protein data on one hand and the morphological data on the other hand were compared and their use was evaluated. A number of commercial Cantaloup F1 hybrid descendants derived from the F1 hybrids by diplohaploidization or single plot descent were studied by IEF-IPG using pH gradients of 4-7 and 6-10. Among the F1 hybrids and their descendants 265 reproducible protein bands could be identified of which 72 were variable as to presence versus absence. The genetic interpretation of the protein pattern as found by IEF-IPG and the use of IEF-IPG in plant breeding was discussed. It was concluded that IEP-IPG of melon seed proteins is a valuable tool in breeding.