Completede novoassembly ofTricholoma bakamatsutakechromosomes revealed the structural divergence and differentiation ofTricholomagenomes

Abstract

Tricholoma bakamatsutake, which is an edible ectomycorrhizal fungus associated with Fagaceae trees, may have diverged before the other species inTricholomasectionCaligata. We generated a highly contiguous whole-genome sequence forT. bakamatsutakeSF-Tf05 isolated in an oak (Quercus salicina) forest in Japan. The assembly of high-fidelity long reads, with a median read length of 12.3 kb, resulted in 13 chromosome-sized contigs comprising 142,068,211 bases with an average GC content of 43.94%. The 13 chromosomes were predicted to encode 11,060 genes. A contig (122,566 bases) presumably containing the whole circular mitochondrial genome was also recovered. The chromosome-wide comparison ofT. bakamatsutakeandT. matsutake(TMA_r1.0) indicated that the basic number of chromosomes (13) was conserved, but the structures of the corresponding chromosomes diverged, with multiple inversions and translocations. Gene conservation and cluster analyses revealed at least three groups inTricholoma. Specifically, allT. bakamatsutakestrains belonged to the ''bakamatsutake'' clade, which is most proximal to the ''caligatum'' clade consisting ofT. caligatumandT. fulvocastaneum. The constructed highly contiguous telomere-to-telomere genome sequence of aT. bakamatsutakeisolate will serve as a fundamental resource for future research on the evolution and differentiation ofTricholomaspecies.