Molecular characterization of a tandem repeat, Afa family, and its distribution among Triticeae

Abstract

We have characterized a so-called D genome specific repetitive DNA sequence (pAs1) of Aegilops squarrosa L. (2n = 14, genome DD) with respect to its DNA sequence and its distribution among Triticeae species. The clone consisted of three units of a repetitive DNA sequence of 336 or 337 base pairs, and was AT rich (65.2%). DNA analyses revealed the presence of the pAs1-like sequences in other genomes of Triticeae species, although the repetition was greatly (as much as 100-fold) variable among the genomes. The repetitive sequences from 10 diploid species were amplified using PCR with specific primers, and the sequential variability was analyzed by the digestion pattern obtained with five restriction enzymes. Since the AfaI site was the most conservatively present in the unit of the repetitive sequences, we named them "Afa family." The analysis clearly displayed the variation of the repetitive sequences regardless of the uniformity of the size of the amplified product. These results indicated that plural amplification events of these repetitive sequences happened independently in the genome evolution of Triticeae.

Single-copy gene fluorescence in situ hybridization and genome analysis: Acc-2 loci mark evolutionary chromosomal rearrangements in wheat

“…2a). Sequences of the D-genome-specific Afa-family repeat pAs1 (Nagaki et al 1995;Nagaki et al 1998) were used to design several oligonucleotide probes. Two of them showed D-genome-specific labeling and were combined ( Table 2).…”

“…(Rayburn and Gill 1986;Nagaki et al 1995), X76300 (Vershinin et al 1994) 3 pAs1-2 6-FAM-TCAGAGTTCATTTGAAATGCTTTTCA 4 NOR 6-FAM-TGGCGCGCGTCAACTTCCGTC 100 X07841 (pTa71) (Barker et al 1988) 5 pTa71…”

Chromosome Sorting in Tetraploid Wheat and Its Potential for Genome Analysis

“…A 260-bp fragment of the in mitosis) was observed 5 hr after the release from the Afa family repeat was prepared using PCR with primers AS-A HU block. The timing of the APM block to accumulate and AS-B on wheat genomic DNA (Nagaki et al 1995). The synchronized cells in metaphase was established after product was separated by agarose gel electrophoresis and the analyzing chromosome suspensions obtained from root 260-bp band was cut from the gel and the DNA was labeled by digoxigenin or biotin using PCR and the same primers.…”

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

“…The amount and distribution of repetitive sequences are various among genomes, but relatively equal among chromosomes in a certain genome. The Afa-family repetitive sequence is one of such sequence (Nagaki et al, 1995). This sequence was first isolated as pAs1 from Aegilops squarrosa L. (2n = 14, genome DD), and described as a D-genome specific repetitive sequence (Rayburn and Gill, 1986a, b).…”