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SUMMARY:REC8-cohesin and chromatin state orchestrate Arabidopsis meiotic r
 ecombination - Andy Tock\, Henderson Lab
DTSTART:20190117T130000Z
DTEND:20190117T133000Z
UID:TALK115762@talks.cam.ac.uk
CONTACT:Ronelle Roth
DESCRIPTION:Homologous chromosomes must pair and recombine to ensure faith
 ful chromosome segregation during meiosis\, a specialised type of cell div
 ision that occurs in sexually reproducing eukaryotes. Meiotic recombinatio
 n initiates by programmed induction of DNA double-strand breaks (DSBs) by 
 the conserved type II topoisomerase-like enzyme SPO11. A subset of meiotic
  DSBs are resolved as crossovers\, whereby reciprocal exchange of DNA occu
 rs between homologous chromosomes. Importantly\, DSBs are non-randomly dis
 tributed along eukaryotic chromosomes\, forming preferentially in permissi
 ve regions known as hotspots. REC8-cohesin organises an axis between the r
 ecombining chromosomes and is required to prevent fragmentation. Defective
  axis assembly occurs in Arabidopsis _rec8_ mutants\, leading to catastrop
 hic non-homologous recombination. In wild type\, REC8 ChIP-seq shows stron
 g enrichment in centromeric heterochromatin\, where recombination is suppr
 essed despite loading of the DSB machinery in these regions. Loss of the h
 eterochromatic marks H3K9me2 and non-CG DNA methylation in _kryptonite/suv
 h4 suvh5 suvh6_ mutants causes remodelling of REC8 and gain of meiotic rec
 ombination in pericentromeric regions\, although centromeric cohesion is m
 aintained. In the chromosome arms\, REC8 is enriched within gene bodies\, 
 exons and GC-rich sequences\, and anti-correlates with transcription. Our 
 findings therefore indicate that as REC8 organises meiotic chromosome arch
 itecture and interhomologue recombination\, it is shaped by multiple chrom
 atin states and transcription. 
LOCATION:Department of Plant Sciences\, Large Lecture Theatre
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