Ectomycorrhizal fungal community structure in a young orchard of grafted and ungrafted hybrid chestnut saplings

Abstract

Ectomycorrhizal (ECM) fungal community of the European chestnut has been poorly investigated, and mostly by sporocarp sampling. We proposed the study of the ECM fungal community of 2-year-old chestnut hybrids Castanea × coudercii (Castanea sativa × Castanea crenata) using molecular approaches. By using the chestnut hybrid clones 111 and 125, we assessed the impact of grafting on ECM colonization rate, species diversity, and fungal community composition. The clone type did not have an impact on the studied variables; however, grafting significantly influenced ECM colonization rate in clone 111. Species diversity and richness did not vary between the experimental groups. Grafted and ungrafted plants of clone 111 had a different ECM fungal species composition. Sequence data from ITS regions of rDNA revealed the presence of 9 orders, 15 families, 19 genera, and 27 species of ECM fungi, most of them generalist, early-stage species. Thirteen new taxa were described in association with chestnuts. The basidiomycetes Agaricales (13 taxa) and Boletales (11 taxa) represented 36% and 31%, of the total sampled ECM fungal taxa, respectively. Scleroderma citrinum, S. areolatum, and S. polyrhizum (Boletales) were found in 86% of the trees and represented 39% of total ECM root tips. The ascomycete Cenococcum geophilum (Mytilinidiales) was found in 80% of the trees but accounted only for 6% of the colonized root tips. These results could help to unveil the impact of grafting on fungal symbionts, improving management of chestnut agro-ecosystems and production of edible fungal species.

Comparative Physiological and Transcriptome Analysis Provide Insights into the Response of Cenococcum geophilum, an Ectomycorrhizal Fungus to Cadmium Stress

“…Studies have shown that C. geophilum isolated from different geographical locations and hosts maintains a high degree of genetic diversity [ 40 , 41 , 42 ]. The inoculation of C. geophilum promoted the growth of host plant roots, improved the absorption and utilization of mineral elements, and regulated the secretion of secondary metabolites of the host plants, thereby enhancing the ability of plants to resist abiotic and biotic stress [ 43 , 44 , 45 ]. Numerous studies have shown that C. geophilum was able to improve the survival of host plants by increasing the biomass, photosynthesis, and mineral nutrient absorption, and weakened the transfer of Cd, lead (Pb), Cu, and zinc (Zn) from soil to plant roots [ 46 , 47 ].…”