What is the Difference Between ITS1 and ITS2?

The main difference between ITS1 and ITS2 lies in their location within the ribosomal RNA (rRNA) gene cluster and their evolutionary origin. ITS1 and ITS2 are spacer DNA regions situated between the rRNA genes in eukaryotes. Here are the key differences between ITS1 and ITS2:

1. Location: ITS1 is located between the 18S and 5.8S rRNA genes, while ITS2 is located between the 5.8S and 28S (or 25S in plants) rRNA genes.
2. Evolutionary Origin: ITS1 corresponds to the ITS in bacteria and archaea, while ITS2 originated as an insertion that interrupted the ancestral 23S rRNA gene.
3. Length Variation: ITS1 has a greater length variation compared to ITS2. The length variation of ITS2 is approximately (180-240 bp).
4. GC Content: ITS1 has a significantly lower GC content than ITS2, which may affect PCR and sequencing efficiencies.

Both ITS1 and ITS2 have been used as DNA barcodes for studying fungal diversity, and they can provide similar results when used as DNA metabarcoding markers for fungi. However, some studies have shown that the choice of primer pairs targeting ITS1 or ITS2 can affect the representation of certain taxa.

Comparative Table: ITS1 vs ITS2

The ITS1 and ITS2 regions are part of the internal transcribed spacer found within the ribosomal DNA of eukaryotes, specifically fungi. These regions are used as barcodes in amplicon-based sequencing of bioaerosols to describe fungal diversity. Here are some differences between ITS1 and ITS2:

GC content is known to affect PCR and sequencing efficiencies, which could impact the performance of ITS1 and ITS2 as barcodes. Additionally, ITS2 has been shown to have a lower variability compared to ITS1, making it more suitable for some applications. The choice between using ITS1 or ITS2 for analysis depends on the specific goals and requirements of the study, as each region has its own biases and characteristics.