Mycorrhizal Associations between Helvella bachu and Its Host Plants

Abstract

Helvella bachu, a prized edible and medicinal fungus, is primarily found in the forests of Populus euphratica, an ancient and endangered species crucial to desert riparian ecosystems. Despite extensive efforts, the isolation of pure cultures and cultivation of fruiting bodies of H. bachu have remained elusive. While some species within the Helvella genus have been confirmed as ectomycorrhizal fungi, others have been considered either saprotrophic or mycorrhizal. By integrating field observations of H. bachu habitat, macro- and micro-anatomical examination of plant root tips, and molecular data from fruiting bodies, mycorrhizae, and host plants, it has been confirmed that H. bachu forms ectomycorrhizal associations with Populus trees. The mycorrhiza of H. bachu displays a light earth color with a curved smooth cylindrical shape. It features a thick mantle and the presence of a Hartig net, accompanied by a small amount of epitaxy mycelia. Morphological observation of the root tips requires meticulous handling, and the paraffin section technique has yielded noteworthy results. Host plants encompass four Populus species, including P. euphratica, P. pruinosa, P. nigra, and P. alba var. pyramidalis (synonym Populus bolleana). A conservation area was established within the young P. euphratica forest at Tarim University, resulting in a 14.75% increase in the quantity of fruiting bodies during the second year. Establishing a conservation area and in situ propagation of H. bachu holds economic and ecological implications. This study will contribute to the conservation of resources related to H. bachu and P. euphratica.