Super-Stretched Pachytene Chromosomes for Plant Molecular Cytogenetic Mapping

We developed a simple technique to mechanically stretch maize pachytene chromosomes more than 20 times longer than their original size. A modified Carnoy’s II solution (6:3:1) ethanol:acetic acid:chloroform was used to fix the meiotic sample. The super-stretched pachytene chromosomes produced from this procedure can be directly used in conventional fluorescence in situ hybridization (FISH) experiments and also for the immunofluorescent in situ detection of DNA methylation. This technique adds a new dimension and higher resolving power to pachytene chromosome-based molecular cytogenetics research.