Isoenzyme Variation in the Barley Genus Hordeum L. I. Alcohol Dehydrogenase and Superoxide Dismutase

Phylogeny of ten species of the genus Hordeum L. as revealed by AFLP markers and seed storage protein electrophoresis

The phylogenetic relationships of 60 accessions representing ten species of the genus Hordeum were investigated based on AFLP markers and seed storage protein SDS-PAGE electrophoresis. A total of 339 AFLP polymorphic markers were scored as a result of fingerprinting the studied taxa using seven AFLP primer combinations, whereas 46 polymorphic protein bands resulted from the water soluble and water non-soluble seed storage protein electrophoresis. The phylogenetic tree deduced from AFLP analysis is concordant in a large extent with that deduced from seed storage protein electrophoresis. The studied taxa were clustered according to their genome type into two main groups representing the Old and New World's species. Inside each group the species were clustered according to their genome type. Highly significant cophenetic correlation coefficient was obtained between both AFLP (0.96) and seed storage protein (0.89) indicating the reliability of the results.

Bromus fasciculatus presl--a third diploid progenitor of Bromus section Genea allopolyploids (Poaceae)

Allozyme variation of ten heterozymes of seven enzymes among five accessions of a rare diploid Bromus fasciculatus was analysed with the use of PAGE and compared with that for six other species of section Genea of the genus Bromus. Allozymes charasteristic for diploids B. tectorum and B. fasciculatus are combined in fixed heterozygous phenotypes of tetraploid B. rubens. Fixed heterozygous phenotypes of tetraploid B. madritensis combine one allozyme of B. fasciculatus with another of diploid B. sterilis at each of the loci studied. Of the three diploids studied, only B. sterilis fits well for a role of a genome donor for the polyploid B. diandrus-rigidus complex. Bromus fasciculatus thus appears to be a diploid ancestor for the two tetraploids of section Genea, B. rubens and B. madritensis.

Species relationships between antifungal chitinase and nuclear rDNA (internal transcribed spacer) sequences in the genus Hordeum

The sequences of the chitinase gene (Chi-26) and the internal transcribed spacer of 18S - 5.8S - 26S rDNA (ITS1) were determined to analyze the phylogenetic relationships among species representing the four basic genomes of the genus Hordeum. Grouping analysis based on data for Chi-26 gene sequences placed Hordeum secalinum (H genome) near the Hordeum murinum complex (Xu genome), and Hordeum bulbosum distant from the other species that carried the I genome. ITS sequence data showed the expected grouping based on the genome classification of the species studied. Different sequences of ITS were detected even in the genomes of the diploid species. The results are interpreted in terms of defective or unfinished concerted evolution processes in each taxon.

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.

The use of RAPD markers inHordeumphylogeny

The phylogenetic relationships among 39 wild Hordeum species, subspecies, and cultivated barley were investigated using RAPD markers as discriminating characters. Seventy-six RAPD fragments were generated using 12 single decameric primers of arbitrary nucleotide sequences. Amplification reactions resulted in fragments ranging in length between 200 and 2000 bp. Clearly resolved bands were scored for their presence or absence in a binary matrix. Amplified products were treated as independent characters to generate a phenogram using the NTSYS-PC package. Tree topology was generally found to be consistent with those based on morphological treatments. However, a few species like H. erectifolium, H. jubatum and, to a lesser extent, H. bulbosum occupied a position different from previous classifications. The results demonstrated that RAPD technology represents a useful and reliable tool for detecting polymorphism for phylogenetic studies. Key words : RAPD analysis, molecular markers, phylogenetic studies, Hordeum species, barley.