Uncovering the morphological and phylogenetic diversity of mushrooms in pecan orchards in the Southwestern United States

Symbiotic relationships between pecan tree roots and mycorrhizal fungi may enhance drought and salt tolerance, nutrient absorption, and disease resistance in pecan (Carya illinoinensis (Wangenh.) K. Koch) orchards of the arid Southwestern United States. Saprotrophic fungi contribute to orchard ecosystem health by breaking down organic matter and enriching soil quality. However, we currently have limited, mostly anecdotal knowledge on mushroom-forming fungi in Southwestern pecan orchards, and studies in other regions primarily focus on ectomycorrhizal fungi. This study provides a novel mycological survey of mushroom-forming fungi (both ectomycorrhizal and saprotrophic) in pecan orchards across New Mexico, Arizona, West Texas, and California. In collaboration with pecan producers, sporocarps from 31 different fungal taxa were collected for morphological, phylogenetic, and ecological analyses. UNITE and NCBI databases aided in taxon identification to construct a maximum-likelihood phylogenetic tree. Common ectomycorrhizal taxa included Scleroderma species, Pisolithus tinctorius, and Tuber lyonii.Saprotrophs included Chlorophyllum molybdites, the regionally-unique Agaricus deserticola, and others. Logistic regression revealed bare soil and tree row location as significant predictors for mycorrhizal fungi presence. This study offers an inaugural characterization of mushroom-forming fungal communities in Southwestern pecan orchards and highlights their potential roles in enhancing orchard ecosystem health and resilience.