# ASV vs OTU for fungal ITS

**URL:** https://forum.qiime2.org/t/asv-vs-otu-for-fungal-its/30735
**Category:** General Discussion
**Tags:** its
**Created:** [July 5, 2024, 9:36am UTC](https://forum.qiime2.org/t/asv-vs-otu-for-fungal-its/30735 "2024-07-05T09:36:20Z")
**Posts on this page:** 1
**Showing post:** 2

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### Author: ![salias](https://forum.qiime2.org/user_avatar/forum.qiime2.org/salias/32/18594_2.png) [@salias](https://forum.qiime2.org/u/salias)
#### Post date: [July 5, 2024, 10:43am UTC](https://forum.qiime2.org/t/asv-vs-otu-for-fungal-its/30735/2 "2024-07-05T10:43:34Z")

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Hi there!

> [@Saptarathi\_Deb](#):
>
> After going through many publications I am seeing comments against the use of ASV for fungal ITS

I'm really curious about that. Could you share the publication reference(s)?

> [@Saptarathi\_Deb](#):
>
> 1. ITS is variable in length and not suitable

I don't see why that should be a problem when creating ASVs with e.g. DADA2. But maybe I'm too naive to understand the implications.

> [@Saptarathi\_Deb](#):
>
> 1. Fungal ITS show intraspecific and intragenomic differences and thus ASV ITS sequences must be clustered to approach species level resolution.

I understand the point, but I don't think OTUs would be better than ASVs in this case. If a species has several ITS sequences, once you assign taxonomy you can either:

- Report ASVs individually like "ASV belonging to species X".
- Collapse (cluster) by any taxonomic level (in this case, species), so you can work with grouped ASVs for each species.

Personally I would stick to ASVs for ITS analyses. In fact, that's what I'm doing right now. But I'm open to change my mind if the reasons are big.

Best,

Sergio

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