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Telomere looping in P. sativum (common garden pea)
Author(s) -
Cesare Anthony J.,
Quinney Nancy,
Willcox Smaranda,
Subramanian Deepa,
Griffith Jack D.
Publication year - 2003
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1046/j.1365-313x.2003.01882.x
Subject(s) - sativum , biology , telomere , pisum , dna , microbiology and biotechnology , gel electrophoresis , genetics , botany
Summary Telomeres vary greatly in size among plants and, in most higher plants, consist of a long array of 5′‐TTTAGGG‐3′/3′‐AAATCCC‐5′ (TTTAGGG) repeats. Recently, telomeric DNA in human, mouse, oxytricha, and trypanosome chromosomes have been found arranged into loops (t‐loops), proposed to sequester the telomere from unwanted repair events and prevent activation of DNA damage checkpoints. We have asked whether t‐loops exist in the higher order plant Pisum sativum (garden pea). DNA was isolated from the shoots and root tips of germinating seeds. Analysis of the telomeric restriction fragments showed that DNA hybridizing to a (TTTAGGG) n probe migrated as a smear centering around 25 kb, and direct sequencing verified the repeat to be (TTTAGGG) n . Total DNA in isolated nuclei was photo‐cross‐linked, and the telomeric restriction fragments were purified by gel filtration. Electron microscopic (EM) analysis revealed DNA molecules arranged as t‐loops with a size distribution consistent with that seen by gel electrophoresis. Some molecules had loops as large as 75 kb. These results show that the arrangement of telomeric DNA into loops occurs in higher plants.