Analysis of Triticeae genomes using DNA markers.
1997
Svitashev S.
Triticeae is a tribe in the grass family Poaceae. It contains cultivated crops such as wheat, rye, barley and many valuable forage grasses. Because of the economical importance, the systematics of Triticeae has attracted many taxonomists and different, sometimes controversial, classification systems have been proposed. Different approaches, such as morphology, crossing ability, chromosome pairing, isoenzymes, RFLP, RAPD and direct sequencing have been used to investigate genetic diversity and evolutionary relationships in the tribe. A central character in the Triticeae systematics is the "genome", which is an equivalent of the basic, monoploid or haploid complete set of chromosomes. According to the presently accepted treatment of Triticeae, species with the same genome (or a particular combination of a few genomes) are combined in one genus. Blot hybridi zation using repeated DNA sequences as probes and RAPD techniques have been applied to study the phylogenetic relationships among species in the two largest genera, Elymus and Hordeum. Our results on the Hordeum species were in good agreement with the present taxonomy of the genus and its division into four groups, with four basic genomes. We also confirmed the presence of the same genome in the H. vulgare complex and H. bulbosum which has been questioned in previous molecular studies. The investigation on Elymus supported its polypheletic origin, but indicated also that the taxonomy of the genus has not been completed. Our analysis, based on the use of genome-specific DNA and RAPD markers, revealed that some species were erroneously included in the genus and should be transferred to other genera within Triticeae. This thesis also contains a brief review of the methods which are most commonly used in plant systematics and genome analysis. Results, limitations and advantages of different approaches are discussed.
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