FISHIS: Fluorescent in situ Hybridization Labeling of Plant Chromosomes in Suspension Increases the Analytical and Preparative Capabilities of the Chromosome Approach

The “chromosome approach”, or isolating chromosomes via flow sorting according their different sizes, resolves genome complexity by focusing sequencing to a small and meaningful part of the whole genome. Plant chromosomes are not so variable in dimensions to permit a direct flow-sorting of single type ones, and this approach is rather limited to plants where cytogenetic mutants by chromosome size are available. A new reliable, fast and cost effective method for Fluorescence In Situ Hybridization In Suspension (FISHIS) of plant chromosomes has been developed that overcomes this limitation allowing chromosome sorting based on total DNA content (size) and a FISH specific chromosome labeling pattern. FISHIS relies on alkaline DNA denaturation and on chromosome hybridization with readily available synthetic, fluorescent labeled, simple sequence repeats (SSR) as probe. By using SSR probes with a known and distinctive labeling patterns, FISHIS lets flow sorting homeologus genomes and several chromosomes from commercial varieties of bread and durum wheat and other Triticeae.