TAR30, a homolog of the canonical plant TTTAGGG telomeric repeat, is enriched in the proximal chromosome regions of peanut (Arachis hypogaea L.)

• Published in: Chromosome research Vol. 30; no. 1; pp. 77 - 90
• Main Authors: Gao, Dongying, Nascimento, Eliza F. M. B., Leal-Bertioli, Soraya C. M., Abernathy, Brian, Jackson, Scott A., Araujo, Ana C. G., Bertioli, David J.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01-03-2022; Springer Nature B.V
• Subjects: Animal Genetics and Genomics; Arachis - genetics; Arachis hypogaea; Biomedical and Life Sciences; Cell Biology; Cell division; Chromosomes; Diploids; Domestication; Fluorescence in situ hybridization; Genome, Plant; Genomes; Human Genetics; Hybridization, Genetic; In Situ Hybridization, Fluorescence; Life Sciences; Nucleotide sequence; Nuts; Oilseeds; Original Article; Plant Genetics and Genomics; Polyploidy; Progenitor cells; Telomere - genetics; Telomeres; FISH; Peanut; Chromosome; Induced allotetraploid; Tandem repeat
• DOI: 10.1007/s10577-022-09684-7
• EISSN: 1573-6849
• ISSN: 0967-3849

Telomeres are the physical ends of eukaryotic linear chromosomes that play critical roles in cell division, chromosome maintenance, and genome stability. In many plants, telomeres are comprised of TTTAGGG tandem repeat that is widely found in plants. We refer to this repeat as canonical plant telomeric repeat (CPTR). Peanut (
Arachis hypogaea
L.) is a spontaneously formed allotetraploid and an important food and oil crop worldwide. In this study, we analyzed the peanut genome sequences and identified a new type of tandem repeat with 10-bp basic motif TTTT(C/T)TAGGG named
TA
ndem
R
epeat (TAR) 30. TAR30 showed significant sequence identity to TTTAGGG repeat in 112 plant genomes suggesting that TAR30 is a homolog of CPTR. It also is nearly identical to the telomeric tandem repeat in
Cestrum elegans
. Fluorescence in situ hybridization (FISH) analysis revealed interstitial locations of TAR30 in peanut chromosomes but we did not detect visible signals in the terminal ends of chromosomes as expected for telomeric repeats. Interestingly, different TAR30 hybridization patterns were found between the newly induced allotetraploid ValSten and its diploid wild progenitors. The canonical telomeric repeat TTTAGGG is also present in the peanut genomes and some of these repeats are closely adjacent to TAR30 from both cultivated peanut and its wild relatives. Overall, our work identifies a new homolog of CPTR and reveals the unique distributions of TAR30 in cultivated peanuts and wild species. Our results provide new insights into the evolution of tandem repeats during peanut polyploidization and domestication.