DNA isolation and genome sequence of the 134-year-old holotype specimen of Boletus subvelutipes Peck.

Abstract

Molecular characterization of type specimens is a powerful tool used in clarifying species identity/circumscription, as well as establishing the taxonomic and phylogenetic status of organisms in question. However, DNA sequencing of aged herbarium collections can be a challenge due to the quantity and quality of DNA still present in the specimens. Herein, we report a custom DNA isolation protocol suitable for processing minute quantities of old specimen tissue and its utilization via high-throughput sequencing technologies to obtain, for the first time, the genome assembly of the 134-year-old holotype of Boletus subvelutipes Peck, a North American fleshy pored mushroom of taxonomic and historical significance. A side-by-side evaluation of our DNA isolation method with that of a commercial "kit" by Qiagen is also presented. By relying on the type material, we have established the genetic identity of B. subvelutipes, as well as providing preliminary phylogenetic evidence for its generic affinities in Neoboletus within Boletaceae. The reference genome of the B. subvelutipes holotype provides a resource for future comparative genomic studies, taxonomic revisions in Boletaceae, and other evolutionary studies of fungi.