title: Involvement of a citrus meiotic recombination TTC-repeat motif in the formation of gross deletions generated by ionizing radiation and MULE activation.
abstract: BACKGROUND
  Transposable-element mediated chromosomal rearrangements require the involvement of two transposons and two double-strand breaks (DSB) located in close proximity. In radiobiology, DSB proximity is also a major factor contributing to rearrangements. However, the whole issue of DSB proximity remains virtually unexplored.
  
  
  RESULTS
  Based on DNA sequencing analysis we show that the genomes of 2 derived mutations, Arrufatina (sport) and Nero (irradiation), share a similar 2 Mb deletion of chromosome 3. A 7 kb Mutator-like element found in Clemenules was present in Arrufatina in inverted orientation flanking the 5' end of the deletion. The Arrufatina Mule displayed "dissimilar" 9-bp target site duplications separated by 2 Mb. Fine-scale single nucleotide variant analyses of the deleted fragments identified a TTC-repeat sequence motif located in the center of the deletion responsible of a meiotic crossover detected in the citrus reference genome.
  
  
  CONCLUSIONS
  Taken together, this information is compatible with the proposal that in both mutants, the TTC-repeat motif formed a triplex DNA structure generating a loop that brought in close proximity the originally distinct reactive ends. In Arrufatina, the loop brought the Mule ends nearby the 2 distinct insertion target sites and the inverted insertion of the transposable element between these target sites provoked the release of the in-between fragment. This proposal requires the involvement of a unique transposon and sheds light on the unresolved question of how two distinct sites become located in close proximity. These observations confer a crucial role to the TTC-repeats in fundamental plant processes as meiotic recombination and chromosomal rearrangements.
authors.affiliation: Centro de Genómica, Instituto Valenciano de Investigaciones Agrarias (IVIA), Moncada, 46113, Valencia, Spain. terol_javalc@gva.es.
authors.forename: Javier
authors.initials: J
authors.lastname: Terol
authors.affiliation: Centro de Genómica, Instituto Valenciano de Investigaciones Agrarias (IVIA), Moncada, 46113, Valencia, Spain. ibanez_vic@gva.es.
authors.forename: Victoria
authors.initials: V
authors.lastname: Ibañez
authors.affiliation: Centro de Investigación Principe Felipe (CIPF), Avda, Autopista del Saler, 16-3, 46012, Valencia, Spain. jcarbonell.cipf@gmail.com.
authors.forename: José
authors.initials: J
authors.lastname: Carbonell
authors.affiliation: Centro de Investigación Principe Felipe (CIPF), Avda, Autopista del Saler, 16-3, 46012, Valencia, Spain. ralonso@cipf.es.
authors.forename: Roberto
authors.initials: R
authors.lastname: Alonso
authors.affiliation: Centro de Genómica, Instituto Valenciano de Investigaciones Agrarias (IVIA), Moncada, 46113, Valencia, Spain. lehues@hotmail.com.
authors.forename: Leandro H
authors.initials: LH
authors.lastname: Estornell
authors.affiliation: CRA-ACM, Consiglio per la Ricerca e la Sperimentazione in Agricoltura, Corso Savoia 190, 95024, Acireale, Catania, Italy. concetta.licciardello@entecra.it.
authors.forename: Concetta
authors.initials: C
authors.lastname: Licciardello
authors.affiliation: Centro Nacional de Análisis Genómico, Parc Científic de Barcelona, 08028, Barcelona, Spain. igut@pcb.ub.cat.
authors.forename: Ivo G
authors.initials: IG
authors.lastname: Gut
authors.affiliation: Centro de Investigación Principe Felipe (CIPF), Avda, Autopista del Saler, 16-3, 46012, Valencia, Spain. jdopazo@cipf.es.
authors.forename: Joaquín
authors.initials: J
authors.lastname: Dopazo
authors.affiliation: Centro de Genómica, Instituto Valenciano de Investigaciones Agrarias (IVIA), Moncada, 46113, Valencia, Spain. talon_man@gva.es.
authors.forename: Manuel
authors.initials: M
authors.lastname: Talon
mesh_terms: D002869:Chromosome Aberrations / Q000528:radiation effects; D002957:Citrus / Q000235:genetics*; D053903:DNA Breaks, Double-Stranded / Q000528:radiation effects; D004260:DNA Repair / Q000528:radiation effects; D004251:DNA Transposable Elements / Q000187:drug effects / Q000235:genetics*; D008540:Meiosis / Q000235:genetics / Q000528:radiation effects; D011839:Radiation, Ionizing; D011995:Recombination, Genetic / Q000528:radiation effects*; D012091:Repetitive Sequences, Nucleic Acid / Q000235:genetics; D017384:Sequence Deletion / Q000235:genetics* / Q000528:radiation effects
chemical_list: D004251:DNA Transposable Elements