Improper chromosome synapsis is associated with elongated RAD51 structures in the maize desynaptic2 mutant.
The RecA homolog, RAD51, performs a central role in catalyzing the DNA strand exchange event of meiotic recombination. During meiosis, RAD51 complexes develop on pairing chromosomes and then most disappear upon synapsis. In the maize meiotic mutant desynaptic2 (dsy2), homologous chromosome pairing and recombination are reduced by ~70% in male meiosis. Fluorescent in situ hybridization studies demonstrate that a normal telomere bouquet develops but the pairing of a representative gene locus is still only 25%. Chromosome synapsis is aberrant as exemplified by unsynapsed regions of the chromosomes. In the mutant, we observed unusual RAD51 structures during chromosome pairing. Instead of spherical single and double RAD51 structures, we saw long thin filaments that extended along or around a single chromosome or stretched between two widely separated chromosomes. Mapping with simple sequence repeat (SSR) markers places the dsy2 gene to near the centromere on chromosome 5, therefore it is not an allele of rad51. Thus, the normal dsy2 gene product is required for both homologous chromosome synapsis and proper RAD51 filament behavior when chromosomes pair.
Franklin
Amie E
AE
Department of Molecular and Cell Biology, 345 Life Sciences Addition, University of California at Berkeley, CA 94720, Berkeley, USA.
Golubovskaya
Inna N
IN
Bass
Hank W
HW
Cande
W Zacheus
WZ
D002874:Chromosome Mapping; D023902:Chromosome Pairing; D032461:Chromosomes, Plant; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D017404:In Situ Hybridization, Fluorescence; D008540:Meiosis; D008854:Microscopy, Electron; D009154:Mutation; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D051135:Rad51 Recombinase; D011995:Recombination, Genetic; D013573:Synaptonemal Complex; D003313:Zea mays / Q000235:genetics* / Q000648:ultrastructure
D004268:DNA-Binding Proteins; D010940:Plant Proteins; D051135:Rad51 Recombinase