Internal transcribed spacer

ITS1 corresponds to the ITS in bacteria and archaea, while ITS2 originated as an insertion that interrupted the ancestral 23S rRNA gene.

[6] Sequence comparison of the eukaryotic ITS regions is widely used in taxonomy and molecular phylogeny because of several favorable properties:[7] For example, ITS markers have proven especially useful for elucidating phylogenetic relationships among the following taxa.

Regardless of the scope of conservation, structure-assisted comparison can provide higher resolution and robustness.

In addition to the universal ITS1+ITS4 primers[30][31] used by many labs, several taxon-specific primers have been described that allow selective amplification of fungal sequences (e.g., see Gardes & Bruns 1993 paper describing amplification of basidiomycete ITS sequences from mycorrhiza samples).

[32] Despite shotgun sequencing methods becoming increasingly utilized in microbial sequencing, the low biomass of fungi in clinical samples make the ITS region amplification an area of ongoing research.