Molecular Biodiversity and De Novo Transcriptomic Analysis of Boletus griseipurpureus: Investigating Associated Genes During Symbiosis with Specific Hosts

Boletus griseipurpureus is an ectomycorrhizal mushroom characterized by a bitter flavor. In this study, specimens were collected from three host plants—Acacia auriculiformis (BgAa), Melaleuca cajuputi (BgMc), and Eucalyptus camaldulensis (BgEc)—and initially classified based on pileus morphology. Molecular biodiversity was investigated using internal transcribed spacer (ITS) DNA barcoding, and comprehensive phylogenetic analysis revealed that B. griseipurpureus populations in southern Thailand clustered according to their symbiotic host species. De novo transcriptome assembly of B. griseipurpureus associated with different hosts was performed to generate unigene datasets, followed by functional gene annotation. A total of 1157 differentially expressed genes (DEGs) were identified and linked to ectomycorrhizal symbiosis. The genes involved in biosynthesis and metabolic processes exhibited host-dependent expression patterns. Furthermore, expression profiles of five selected genes—major facilitator superfamily (MFS) substrate transporter, phosphatase II, hexose transporter, terpenoid synthase, and fungal hydrophobin—were consistent between DEG analysis and semi-quantitative RT-PCR validation. These findings suggest that these genes play important roles in ectomycorrhizal symbiosis and the biosynthesis of bioactive compounds in B. griseipurpureus, with expression influenced by host association. This study provides valuable insights into the molecular biodiversity and gene regulation underlying ectomycorrhizal symbiosis, contributing to a better understanding of the biological processes in B. griseipurpureus.