A LIGHT-MICROSCOPIC ATLAS OF MEIOSIS IN ARABIDOPSIS-THALIANA

An atlas of meiosis in Arabidopsis thaliana, encompassing all stages f rom preleptotene to telophase II and early microspore formation, is pr esented in detail for the first time. The photomicrographs and descrip tions are based on staining with the DNA fluorochrome 4',6-diamidino-2 -phenylindole (DAPI) combined with a spreading procedure, or haematoxy lin-iron alum (HIA) staining. Despite previous reservations about the practicality of cytogenetic meiotic analysis in Arabidopsis due to its small genome size, good-quality and clearly analysable preparations o f all meiotic stages were obtained. This atlas of normal, wild-type me iosis is considered an essential prerequisite to informed analyses of meiotic mutants. Furthermore, extended prophase I chromosomes, particu larly at the pachytene stage, offer considerable potential for produci ng a detailed cytogenetic map (karyotype) of Arabidopsis chromosomes w ith the additional prospect of high-resolution physical mapping based on fluorescence in situ hybridization (FISH) of defined DNA probes to these extended chromosomes.