One-fits-all fluorescence in situ hybridisation (FISH) with single and high-copy DNA probes for Arecoideae species.

Fluorescent in situ hybridisation (FISH) has been the most powerful and versatile technique in cytogenetics research to answer and validate biological questions associated with the structure, organisation, variation, and evolution of individual chromosomes and entire genomes. A standard reference FISH approach that requires little or no modifications is desired to minimise the time and costs in fine-tuning the cumbersome FISH approach. However, the available published FISH methods do not provide a comprehensive step-by-step technique that works across Arecoideae taxa. Here, using single- and high-copy DNA probes, we report a FISH approach developed for Elaeis guineensis that gave reproducible results in three commercially important Arecoidae species: Elaeis oleifera, Cocos nucifera and Phoenix dactylifera. Our protocol covers detailed experimentation steps from preparing high-quality chromosome spreads to localising the different DNA probes on chromosomes of the selected species. We propose the established method here as a reference platform for research communities to embark on the molecular cytogenetics-related study in oil palm and other distantly related species within over 100 genera of the Arecoideae, the largest subfamily in Arecaceae.