Plant & Animal Genomes XI Conference Plant & Animal Genomes XI ConferenceJanuary 11-15, 2003
Town & Country Convention Center
San Diego, CA
Workshop: Plant Cytogenetics
During meiotic prophase, telomeres attach to the nuclear envelope and cluster in a chromosome end arrangement called the bouquet. The widely conserved bouquet is unique to meiosis and thought to facilitate homologous chromosome synapsis and recombination. To better understand the role of telomeres during meiosis, we have used 3-D molecular cytology to characterize the nuclear architecture of pollen mother cells fixed during meiotic prophase. Telomere FISH and chromosome painting studies in maize and oats (wildtype nuclei movies) defined the onset of telomere clustering as occurring at zygotene, just prior to homologous chromosome synapsis. In order to examine the genetic control bouquet functions, we screened several maize meiotic mutants for telomere localization defects using 3-D FISH as an assay. We discovered novel telomere-misplacement phenotypes for two different desynaptic mutants, desynaptic (dy) and desynaptic1 (dsy1). Alleles of dsy1 result in a partial bouquet phenotype, whereas dy results in premature detachment of telomeres from the nuclear envelope at pachytene (mutant nuclei movies). Each of these phenotypes were upstream of previously reported defects. The dsy1 mutation is known to impair the progression of homologous synapsis, whereas the dy mutation is known to reduce recombination rates. Thus the distinct phenotypes we observed may reflect two separable meiotic telomere functions, one involving bouquet-stage synapsis and another involving postbouquet crossover control. Other plant species exhibit some variation on the timing (hexaploid wheat) or location (Arabidopsis) of the telomere clustering phenomenon.