DISCUSSION
A few decades ago, the introduction of molecular biology and tools such as PCR and the pros and cons of NGS can be described as a very fast procedure and that has a high stream reading performance, although the length of the reading can be limiting (400 bp). For NGS, we decided to use the ITS region, because it represents a good element among a less variable region such as LSU (Stockinger et al. 2010). NGS allowed to obtain more data at a lower cost compared to other techniques such as the Sanger sequencing.
There are very few studies of the use of NGS in soil fungal communities, in Ecuador. Most studies are oriented to the description of the diversity of arbuscular mycorrhizal fungi (AMF) and are not specific on forest soil. The studies include tropical montane forests (Haug et al. 2019) and Andean forest (Dueñas et al. 2020) associated with potato cultivation in the Andean part of Loja and Quito (Senés-Guerrero & Schüßler 2016; Loján et al. 2017). There are also studies of the communities of AMF with plants growing in crude oil-contaminated sites in the Amazon region of Ecuador (Garcés‐Ruiz et al. 2019).
The study of AMF in montane tropical forests (Dueñas et al. 2010), shows that the Acaulosporaceae and Glomeraceae families presented a higher abundance of out. Our results showed a higher abundance of ASVs with Mortirelacea and Nectriaceae families. In the case of AMF, taking into account altitude gradients, Haug et al. (2019), reported that the largest number of OTUs was dominated by the genus Acaulospora andGlomu s. However, our report showed a greater abundance of ASVs with the genus Mortirella and Fusarium .
In the case of AMF associated to potato, the presence of a composite base “core” consisting mainly of Acaulospora sp .,Cetraspora nodosa , Claroideoglomus sp . andRhizophagus sp . strains has been escribed (Senés-Guerrero & Schüßler 2016: Loján et al. 2017). In the present study, these species were found at a very low frequency or were not detected at all (e.g.Rhizophagus sp .). In fungal communities in areas contaminated with crude oil, diversity was very similar, dominating in this caseRhizophagus (Garcés‐Ruiz et al. 2019).
The most abundant genus in our study: Mortierella , is ubiquitous and has 85 species (Ainsworth et al. 2008). Mortierella is often found in correspondence with decaying leaves due to her saprophytic nature (Tamayo-Vélez et al. 2018) as in the high mountain closed forest. In regard to alpha diversity, it was very similar among all sampling sites. The values reported here are similar to those found for other regions of the world with altitudes above 2,000 meters above sea level (Argüelles-Moyao et al. 2018). Others abundant genera reported here correspond to the yeasts Saitozyma sp . and Solicocoozyma sp ., which occurs in forest soils (Mašínová et al. 2017)
When reviewing the beta diversity estimated by the Bray-Curtis method, it can be observed that samples from locations A and B show a similarity in their distribution compared to location C which is consistent with Venn analysis showing that locations A and B share a higher percentage of the genera (10.8%). However, the variability in the distribution of fungal communities between different altitudes was not so evident, due to the small altitude gradient used in the study (≈ 550 masl). Studies on AMF have shown that the number of shared OTUs at neighbouring elevations would explain the effect of elevation on smaller gradients, where distinct AMF communities have not been found (De Beenhouwer et al. 2015; Egan et al. 2017; Liu et al. 2015).