Contrasted patterns of crossover and non-crossover at Arabidopsis thaliana meiotic recombination hotspots.
The vast majority of meiotic recombination events (crossovers (COs) and non-crossovers (NCOs)) cluster in narrow hotspots surrounded by large regions devoid of recombinational activity. Here, using a new molecular approach in plants, called "pollen-typing", we detected and characterized hundreds of CO and NCO molecules in two different hotspot regions in Arabidopsis thaliana. This analysis revealed that COs are concentrated in regions of a few kilobases where their rates reach up to 50 times the genome average. The hotspots themselves tend to cluster in regions less than 8 kilobases in size with overlapping CO distribution. Non-crossover (NCO) events also occurred in the two hotspots but at very different levels (local CO/NCO ratios of 1/1 and 30/1) and their track lengths were quite small (a few hundred base pairs). We also showed that the ZMM protein MSH4 plays a role in CO formation and somewhat unexpectedly we also found that it is involved in the generation of NCOs but with a different level of effect. Finally, factors acting in cis and in trans appear to shape the rate and distribution of COs at meiotic recombination hotspots.
Institut Jean-Pierre Bourgin UMR1318 INRA-AgroParisTech, Versailles, France.
Jan
J
Drouaud
Hossein
H
Khademian
Laurène
L
Giraut
Vanessa
V
Zanni
Sarah
S
Bellalou
Ian R
IR
Henderson
Matthieu
M
Falque
Christine
C
Mézard
D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000235:genetics; D003434:Crossing Over, Genetic; D005785:Gene Conversion; D018745:Genome, Plant; D008540:Meiosis / Q000235:genetics*; D011058:Pollen / Q000235:genetics*; D011995:Recombination, Genetic
D029681:Arabidopsis Proteins; C494377:MSH4 protein, Arabidopsis