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Abstract

The distribution of highly repetitive DNA sequences on chromosomes of tetraploid and hexaploid cytotypes of Aegilops crassa (Dcr1Xcr and Dcr1XcrDcr2 genomes) was studied using C-banding and in situ hybridization analyses with the pSc119, pAs1 and pTa794 DNA clones. In total, 14 tetraploid and five hexaploid accessions were examined. All chromosomes can be identified by their C-banding and ISH pattern with the pAs1 DNA clone. Only a few pSc119 hybridization sites were observed in the telomeric regions of several chromosomes. We found a high level of C-banding polymorphism and only minor variations in labeling patterns. The position of C-bands generally coincided with the location of the pAs1 sequence. Three 5S rDNA loci were detected in tetraploid Ae. crassa, whereas five pTa794 ISH sites were observed in 6x Ae. crassa. All the hexaploid accessions differed from the tetraploids by a reciprocal non-centromeric translocation involving chromosomes A and N. Three additional translocations were detected in the accessions analyzed. The Dcr1 genome of 4x Ae. crassa is highly modified compared with the D genome of the progenitor species Ae. tauschii. Because of the large amount of chromosomal rearrangements, the origin of the Xcr genome remains unknown. The second Dcr2 genome of 6x Ae. crassa is different from the Dcr1 genome but is similar to the D-genome chromosomes of Ae. tauschii, indicating that no additional large rearrangements occurred at the hexaploid level.

DArTseq-based analysis of genomic relationships among species of tribe Triticeae

“…Using both types of data, we clarified the extent of genomic similarity among Aegilops species in different sections and clusters and the evolutionary relationships between diploid and polyploid species in Aegilops and Triticum species. We confirmed the already known genomic constitutions of some polyploid species of Aegilops and Triticum species, and provided evidence-based explanation for the origin of the unidentified (X) genomes 2 , 16 , 19 – 21 in Ae. crassa , Ae.…”

“…vavilovii [X va D va S va ], and Ae. columnaris [U c X c ]) 2 , 16 , 19 – 21 are most likely to be traced to Ae. speltoides or Ae.…”

Genetic diversity of the D-genome in T. aestivum and Aegilops species using SSR markers

“…crassa, indicating more differences between the D-genome of these two species. According to Badaeva et al (1998), the D cr1 -genome of 49 Ae. crassa is derived from the D-genome of Ae.…”

“…cylindrica were inherited from different biotypes of Ae. tauschii (Badaeva et al 1998;Caldwell et al 2004). However, Ae.…”

“…Genetic diversity in Ae. crassa was evaluated using isozymes (Nakai 1989), SSR markers (Zhang and Dvorak 1992;Dubkovsky and Dvorak 1995) and in situ hybridization (Badaeva et al 1998). Potential agronomic traits, such as cytoplasmic male sterility (Murai and Tsunewaki 1993) and salinity tolerance (Liu et al 2002), were also identified in Ae.…”