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Inter- and intraspecific hypervariability in interstitial telomeric-like repeats (TTTAGGG)n in Anacyclus (Asteraceae).

Abstract：

Background and Aims:Interstitial telomeric repeat (ITR) sites, consisting of tandem repeats of telomeric motifs localized at intrachromosomal sites, have been reported in a few unrelated organisms including plants. However, the causes for the occurrence of ITRs outside of the chromosomal termini are not fully understood. One possible explanation are the chromosomal rearrangements involving telomeric sites, which could also affect the location of other structural genome elements, such as the 45S rDNA. Taking advantage of the high dynamism in 45S rDNA loci previously found in Anacyclus (Asteraceae, Anthemideae), the occurrence and patterns of variation of ITRs were explored in this genus with the aim of finding common underlying causes. Methods:In total, 132 individuals from 44 populations of nine species were analysed by fluorescence in situ hybridization using an Arabidopsis-type telomeric sequence as a probe. Key results:Variable presence of ITR sites was detected in six out of nine species of Anacyclus, ranging from two to 45 sites and showing contrasting chromosomal locations and a differential presence of the ITR site on homologous chromosome pairs. At the intraspecific level, the ranges were as large as 0-12 ITR sites. Although only 26 % of the total observed ITR sites were localized in chromosomes bearing 45S rDNA loci, all cases of interstitial 45S rDNA reported in a previous work co-occurred with ITRs in close proximity in the same chromosome arms. Conclusions:High levels of ITR polymorphism within a single species have not been previously reported in plants and suggest that this pattern might have been overlooked due to insufficient sampling. Although ancient Robertsonian translocations or the amplification of terminal 45S rDNA sites cannot, on their own, explain all of the levels of variability in ITRs reported here, there are suggestions that they may have been involved in the evolutionary history of this genus or its ancestors in Anthemideae.

journal_name

Ann Bot

journal_title

Annals of botany

authors

Rosato M,Álvarez I,Feliner GN,Rosselló JA

doi

10.1093/aob/mcy079

subject

Has Abstract

pub_date

2018-08-27 00:00:00

pages

387-395

issue

eissn

0305-7364

issn

1095-8290

pii

5003216

journal_volume

122

pub_type

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Inter- and intraspecific hypervariability in interstitial telomeric-like repeats (TTTAGGG)n in Anacyclus (Asteraceae).