Ectomycorrhizal Fungi Associated with Pinus cembroides subsp. orizabensis, an Endemic Pine in the Arid Zones of the Oriental Basin, Puebla, Mexico

Ectomycorrhizal fungi (EMF) associated with the roots of Pinus cembroides subsp. orizabensis, a key pinyon pine species for local forestry in the Oriental Basin, Puebla, Mexico, were identified and analyzed. The study aimed to evaluate the diversity of EMF in this endemic pine across three sampling transects (T1, T2, T3), each located in sites with different vegetation compositions and pine cover. In each site, a 100 m × 25 m transect was established, and root tips colonized by EMF were collected for morphological and molecular identification. Alpha (α) and beta (β) diversity were calculated for each transect. A total of 16 EMF morphotypes were identified, and molecular analysis confirmed four taxa: Geopora arenicola, Rhizopogon aff. subpurpurascens, Tomentella sp. 1, and Tricholoma sp. 1. The transect with the highest P. cembroides cover showed the greatest fungal richness. Beta diversity, as measured by Sørensen index partitioning, revealed a 30% species turnover between T1 and T2 and a 60% turnover between T2 and T3, suggesting distinct fungal communities. In contrast, no turnover but a nested pattern was observed between T1 and T3, indicating that the less diverse community is a subset of the richer one. These results show that EMF composition varies with pine cover and vegetation heterogeneity, highlighting the influence of disturbance on fungal diversity. This is the first report of EMF fungi associated with Pinus cembroides subsp. orizabensis, as well as the first record of G. arenicola in arid pine forests in Mexico.