中华腐生牛肝菌染色体水平参考基因组的构建及其腐生适应性分析OA

The majority of fungi in the order Boletales are ectomycorrhizal symbionts.Buchwaldoboletus xylophilus,a rare saprotrophic species within this order,is recognized as the second globally cultivated bolete mushroom,which holds significant value for both scientific research and industrial applications.However,genomic information for this species is currently nonexistent.In this study,PacBio sequencing technology combined with Hi-C-assisted assembly was employed to construct,for the first time,a chromosome-level high-quality genome of B.xylophilus.The genome comprises 12 chromosomes with a total length of 30.13 Mb,a GC content of 50.38%,a contig N50 of 2.64 Mb,and a BUSCO completeness of 98.5%;11 195 protein-coding genes were annotated.Comparative genomic analyses revealed that the transposable element content(9.97%)in B.xylophilus is significantly lower than that in symbiotic boletes(e.g.,～39.5%in Boletus edulis),suggesting enhanced genome stability under the saprotrophic strategy.Gene family evolution exhibited a"contraction-expansion"synergistic pattern:contractions were mainly observed in functions related to cell wall modification and transcriptional regulation,whereas expansions involved environmental sensitivity,lignocellulose degradation[e.g.,2OG-Fe(Ⅱ)oxygenases],and DNA repair,adapting oneself to the dead wood decomposition niche.CAZyme analysis demonstrated that this fungus is enriched in glycoside hydrolases(GHs,42.33%)and auxiliary activities(AAs,14.88%),conferring efficient plant cell wall degradation capabilities.Its secondary metabolite gene clusters are relatively few(25),reflecting an energy allocation strategy biased toward carbon acquisition rather than complex secondary metabolism.Phylogenetic analysis confirmed its affiliation with the subfamily Chalciporoideae of the family Boletaceae,with a divergence time estimated at 13.84-33.82 million years ago.Synteny comparisons revealed that although the core genome of Boletales was conserved,approximately 39%of genes exhibited non-syntenic distribution and chromosomal rearrangements,suggesting possible association with the adaptive divergence of different nutritional strategies.This study elucidates the adaptive molecular characteristics of the B.xylophilus genome for the first time,providing theoretical foundations and genomic resources for revealing mechanisms of fungal ecological adaptation and advancing genetic breeding and biodegradation applications of this species.