C-banding patterns of Hordeum chilense and of Triticum aestivum 'Chinese Spring' – H. chilense disomic addition lines were analyzed and compared with in situ hybridization patterns using a biotin-labeled highly repetitive Triticum tauschii DNA sequence, pAs1, and a wheat 18S–26S rDNA probe. All seven H. chilense chromosomes pairs and the added H. chilense chromosomes present in the addition lines were identified by their characteristic C-banding pattern. Chromosome morphology and banding patterns were similar to those of the corresponding chromosomes present in the parent H. chilense accession. A C-banded karyotype of the added H. chilense chromosomes was constructed and chromosome lengths, arm ratios, and relative length, as compared with chromosome 3B, were determined. The probe pAs1 was found to hybridize to specific areas on telomeres and interstitial sites along the chromosomes, allowing the identification of all seven pairs of the H. chilense chromosomes. Comparison of the patterns of distribution o...

Characterization of Hordeum chilense chromosomes by C-banding and in situ hybridization using highly repeated DNA probes

We have characterized three cDNA clones corresponding to proteins CM1, CM3 and CM16, which represent the three types of subunits of the wheat tetrameric inhibitor of insect α-amylases. The deduced amino acid sequences of the mature polypeptides are homologous to those of the dimeric and monomeric α-amylase inhibitors and of the trypsin inhibitors. The mature polypeptides are preceded by typical signal peptides. Southern blot analysis of appropriate aneuploids, using the cloned cDNAs as probes, has revealed the location of genes for subunits of the CM3 and of the CM16 type within a few kb of each other in chromosomes 4A, 4B and 4D, and those for the CM1 type of subunit in chromosomes 7A, 7B and 7D. Known subunits of the tetrameric inhibitor corresponding to genes from the B and D genomes have been previously characterized. No proteins of this class have been found to be encoded by the A genome in hexaploid wheat (genomes AA, BB, DD) or in diploid wheats (AA) and no anti α-amylase activity has been detected in the latter, so that the A-genome genes must be either silent (pseudogenes) or expressed at a much lower level.

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Cloning of cDNA and chromosomal location of genes encoding the three types of subunits of the wheat tetrameric inhibitor of insect α-amylase.

α-amylase activities of agricultural insect pests are specifically affected by different inhibitor preparations from wheat and barley endosperms

Several useful alien gene transfers have been reported from related species into wheat (Triticum aestivum), but very few publications have dealt with the development of wheat/barley (Hordeum vulgare) introgression lines. An overview is given here of wheat × barley hybridization over the last forty years, including the development of wheat × barley hybrids, and of addition and translocation lines with various barley cultivars. A short summary is also given of the wheat × barley hybrids produced with other Hordeum species. The meiotic pairing behaviour of wheat × barley hybrids is presented, with special regard to the detection of wheat–barley homoeologous pairing using the molecular cytogenetic technique GISH. The effect of in vitro multiplication on the genome composition of intergeneric hybrids is discussed, and the production and characterization of the latest wheat/barley translocation lines are presented. An overview of the agronomical traits (β-glucan content, earliness, salt tolerance, sprouting resistance, etc.) of the newly developed introgression lines is given. The exploitation and possible use of wheat/barley introgression lines for the most up-to-date molecular genetic studies (transcriptome analysis, sequencing of flow-sorted chromosomes) are also discussed.

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Wheat-barley hybridization: the last 40 years

A Triticum durum cDNA library prepared from developing endosperm (22 days after flowering (DAF] was screened using synthetic oligonucleotide probes covering part of the CM3 and CM16 N-terminal protein sequences. A full-length cDNA clone (pTd78) encoding the CM16 protein (chloroform/methanol-soluble protein) was isolated and characterized. To our knowledge this is the first characterization of a clone coding for a wheat CM protein. The CM16 protein is synthesized as a preprotein with a signal peptide of 24 residues, the molecular weight of the mature protein being 13,438 Da. As other members of the cereal trypsin/alpha-amylase inhibitor family, the CM16 protein contains 10 cysteine residues, their position being well conserved. In developing endosperm the highest level of CM16 mRNA was detected at mid-maturation.

Cloning and characterization of a cDNA encoding the wheat (Triticum durum Desf.) CM16 protein

The meiotic behaviour of the amphiploid Hordeum chilense X Triticum turgidum conv durum using a C-banding staining method is studied Nine pairs of chromosomes at metaphase-1 (4A, 7A and the seven of the B genome) were identified and the remaining wheat chromosomes (1A, 2A, 3A, 5A and 6A) and seven of the chilense (1 to 7 Hchchromosomes) were assigned to its particular genome A similar mean number of univalents from parental genomes (wheat and wild barley) were found No meiotic pairing between chilense and turgidum chromosomes was detected Differences in the meiotic behaviour per chromosome and amongst genomes are explained on the basis of cytomorphological and heterochromatin characteristics

Meiotic pairing of the amphiploid Hordeum chilense X Triticum turgidum conv. durum studied by means of Giemsa C-banding technique

Three proteins (components 1, 2, and 4) of the non-prolamin, 70% ethanol soluble fraction from the endosperm of Hordeum chilense have been identified as putative subunits of the tetrameric inhibitors active against insect α-amylases. In experiments carried out with the synthetic alloploid Tritordeum (H. chilense x Triticum turgidum conv. durum), previously described proteins from T. turgidum, designated CM2, CM3 and CM 16, have been also identified as subunits of α-amylase inhibitors. Genes for components 1 and 4 of H. chilense have been located in chromosomes 4Hch and 7Hch, based on the analysis of H. chilense-T.turgidum addition lines. Subunits of the inhibitors from wheat and from cultivated barley had been previously assigned to chromosomes of the same homoeology groups.

Subunits of tetrameric α-amylase inhibitors of Hordeum chilense are encoded by genes located in chromosomes 4Hch and 7Hch

Polyacrylamide and starch gel electrophoresis of esterase (EST), glutamate oxaloacetate transaminase (GOT) and phosphoglucomutase (PGM) isozymes in Hordeum chilense, Triticum turgidum conv. durum, the amphiploid H. chilense X T. turgidum (Tritordeum), and the durum wheat/H. chilense monosomic addition lines revealed the chromosomal location of one EST locus, two GOT loci and one PGM locus. Loci Est-Hch1 and Got-Hch2 were found on chromosome 6Hch,Got-Hch3 on chromosome 3Hch, and Pgm-Hch1 on chromosome 4Hch. These results lend evidence for the assumed homoeology relationships between chromosomes of Triticeae species.

Chromosomal location of structural genes controlling isozymes in Hordeum chilense : 3. Esterases, glutamate oxaloacetate transaminase and phosphoglucomutase.

A study of 6-phosphogluconate dehydrogenase and malate dehydrogenase isozyme expression in Triticum turgidum conv. durum /Hordeum chilense monosomic addition lines has revealed the location of two structural genes, 6-pgd-H (ch) 2 and Mdh-H (ch) 1, on chromosome 1H(ch) of H. chilense. The homoeology between 1H(ch) and other chromosome of Triticeae related species is discussed on the basis of isozyme gene analysis.

J. A. Fernandez

Papers

Meiotic pairing of the amphiploid Hordeum chilense X Triticum turgidum conv. durum studied by means of Giemsa C-banding technique

Subunits of tetrameric α-amylase inhibitors of Hordeum chilense are encoded by genes located in chromosomes 4Hch and 7Hch

Chromosomal location of structural genes controlling isozymes in Hordeum chilense : 3. Esterases, glutamate oxaloacetate transaminase and phosphoglucomutase.

Chromosomal location of structural genes controlling isozymes in Hordeum chilense : 1. 6-Phosphogluconate dehydrogenase and malate dehydrogenase.