Plant & Animal Genomes XI Conference Plant & Animal Genomes XI ConferenceJanuary 11-15, 2003
Town & Country Convention Center
San Diego, CA
Workshop: Plant Cytogenetics
The development and application of improved cytogenetic techniques combined with molecular genetics has enabled the rapid expansion of meiosis research in the model dicotyledonous plant Arabidopsis thaliana. We are currently dissecting the events that occur prior to and during chromosome synapsis in this species. FISH analysis indicates that telomeres show a persistent colocalisation with the nucleolus throughout meiotic interphase and associate in pairs, preceding general homologous chromosome synapsis. Centromeres on the other hand do not display any tendency to presynaptic association in Arabidopsis. ASY1 is one of several Arabidopsis genes that are required for synapsis. A T-DNA insertional mutant (asy1) exhibits complete asynapsis, but nevertheless forms a few (0-3) bivalents at metaphase I, probably as a consequence of telomere pairing which is unaffected in the mutant. Antibody raised against recombinant Asy1 protein expressed in E. coli has been used to investigate the expression and localisation of the protein in male and female meiocytes in Arabidopsis and the closely related crop species Brassica oleracea. This reveals that Asy1 begins to accumulate as punctate foci during premeiotic interphase, peaking at leptotene and becoming more continuous during zygotene and pachytene, before gradually decreasing and shedding from the chromosome axes during late prophase. EM studies using immunogold labelled Ab indicate that Asy1 is localised to axis-associated chromatin and is not an integral component of the SC.