Chromosomal rearrangements in wheat: their types and distribution

Abstract

Four hundred and sixty polyploid wheat accessions and 39 triticale forms from 37 countries of Europe, Asia, and USA were scored by C-banding for the presence of translocations. Chromosomal rearrangements were detected in 70 of 208 accessions of tetraploid wheat, 69 of 252 accessions of hexaploid wheat, and 3 of 39 triticale forms. Altogether, 58 types of major chromosomal rearrangements were identified in the studied material; they are discussed relative to 11 additional translocation types described by other authors. Six chromosome modifications of unknown origin were also observed. Among all chromosomal aberrations identified in wheat, single translocations were the most frequent type (39), followed by multiple rearrangements (9 types), pericentric inversions (9 types), and paracentric inversions (3 types). According to C-banding analyses, the breakpoints were located at or near the centromere in 60 rearranged chromosomes, while in 52 cases they were in interstitial chromosome regions. In the latter case, translocation breakpoints were often located at the border of C-bands and the euchromatin region or between two adjacent C-bands; some of these regions seem to be translocation "hotspots". Our results and data published by other authors indicate that the B-genome chromosomes are involved in translocations most frequently, followed by the A- and D-genome chromosomes; individual chromosomes also differ in the frequencies of translocations. Most translocations were detected in 1 or 2 accessions, and only 11 variants showed relatively high frequencies or were detected in wheat varieties of different origins or from different species. High frequencies of some translocations with a very restricted distribution could be due to a "bottleneck effect". Other types seem to occur independently and their broad distribution can result from selective advantages of rearranged genotypes in diverse environmental conditions. We found significant geographic variation in the spectra and frequencies of translocation in wheat: the highest proportions of rearranged genotypes were found in Central Asia, the Middle East, Northern Africa, and France. A low proportion of aberrant genotypes was characteristic of tetraploid wheat from Transcaucasia and hexaploid wheat from Middle Asia and Eastern Europe.

Non-parental banding patterns in recombinant inbred line population of maize with SSR markers

“…The different satellite DNA sequences are organized into blocks and are present at multiple positions (Elgin, 1996). The ability of these sequences to change their copy number is thought to promote chromosomal rearrangements (Badaeva et al, 2007). For example, satellite DNA families are involved in recombination events in Drosophila (Kuhn et al, 2009) and play a central role in chromosome evolution in plants (Raskina et al, 2008).…”

Chromosomes as Tools for Discovering Biodiversity – The Case of Erythrinidae Fish Family

“…However, accumulated data from eukaryotic species of diverse taxonomic origins have challenged this view over the past few years (Bonaccorsi & Lohe, 1991), supporting a major role of repetitive DNA sequences in the structural and functional evolution of genes and genomes in a variety of organisms (Biémont & Vieira, 2006). Today, many studies have been conducted using dispersed or in tandem repetitive DNA sequences as probes for FISH cytogenetic mapping in distinct living organisms; these sequences include simple sequence repeats (Figure 2a might even generate a unique FISH karyotype for each species (e.g., Badaeva et al, 2007), enabling an evolutionary and phylogenetic view of related species. In contrast to functional genes, repetitive DNA sequences are thought to have evolved under different conditions, escaping from the selective pressures that act on the non-repetitive segments (Charlesworth et al, 1994).…”

Molecular-cytogenetic analysis of triticale and wheat lines with introgressions of the tribe Triticeae species genetic material

“…Наблюдаемые нами изменения в распределении блоков повтора pSc119.2 на хромосоме 1B у линий 21-1, 12, 20 и 23-4 могут свидетельствовать о произошедших в про-цессе создания гибридных линий тритикале перестройках между хромосомами пшеницы. Так, например, Е. Бадаева с коллегами (Badaeva et al, 2007) выявили в сумме около 20 типов перестроек у разных образцов мягкой пшеницы и тритикале. Следует отметить, что наибольшее количест-во перестроек (у 7 из 10 изученных линий) нами было выявлено в первой гомеологической группе хромосом.…”