The molecular–cytogenetic analysis of grasses and its application to studying relationships among species of the Triticeae

Abstract

An analysis of four species from the genus Secale, including the study of different accessions, has shown that the properties of DNA clones of monomer units from three repeated sequence loci, namely, Ter, Nor, and 5S DNA, proved to be representative of the entire loci from which they were isolated. This finding in Secale species, including the discovery of a new locus for 5S DNA on chromosome 5R, has been used to interpret information on the Ter, Nor, and 5S DNA loci from 15 species in the Triticeae complex. The evolutionary relationship among species suggested by the DNA sequence data has shown many consistencies with a number of other characters such as those used in classical systematics, as well as geographical distribution data and isozyme and chromosome-pairing studies. Apparent inconsistencies such as a close relationship between the R and P genomes at the Ter loci are interpreted in terms of amplification-deletion phenomena known to occur at repetitive sequence loci. In addition, this study included species endemic to Australia and thus provided a broad time span in which to consider some features of repeated sequence family evolution, such as the conservation of certain parts of 5S DNA spacer regions.

Identification of individual barley chromosomes based on repetitive sequences: Conservative distribution of Afa-family repetitive sequences on the chromosomes of barley and wheat.

“…6). These blocks also appeared in the hybridization of 350-bp family sequences with Secale cereale, Critesion bogdanii, and Pseudoroegneria libanotica chromosomes (Appels, 1989;Tsujimoto and Gill, 1991;Tsujimoto, unpublished data), indicating thereby that distal heterochromatin regions of Triticeae chromosomes remain condensed even in the interphase. The Afa-family sequences were located proximal to the HvRT repetitive sequences, and did not always formed condensed blocks like the HvRT family in interphase (Fig.…”

Oat–maize chromosome addition lines: A new system for mapping the maize genome

“…Plant repetitive sequences that are apparently speciesspecific were first isolated from rye (24,25) and later found in many other species (26). Comparative studies revealed a strong correlation between the proportion of species-specific repeated families in a genome and phylogenetic relationships (27,28).…”

Dynamics of Tandem Repetitive Afa-Family Sequences in Triticeae, Wheat-Related Species

“…In the case of tandem repeats, however, the specificity is not well explained because details of the amplification and conservation mechanisms are still unknown even though some models have been proposed (Dover 1982(Dover , 1986(Dover , 1993Dover and Flavell 1982). These sequences were reported in various taxa of eukaryotes, e.g., higher plants (Appels et al 1978(Appels et al , 1989Rayburn and Gill 1986a;Irifune et al 1995), mollusks (Plohl and Cornudella 1996), insects (Sonoda et al 1993;Bachmann et al 1994), brine shrimp (Landsberger et al 1992), and mammals (Modi 1993). All these genome-specific repeats consist of a few hundred base pairs (100-400 bp) as the unit.…”