A review of existing whole genome data suggests lichen mycelia may be haploid or diploid

Abstract

Abstract Fungi exhibit some of the greatest reproductive diversity among Eukaryotes. In addition to sexual and asexual reproduction, fungi engage in parasexual processes (e.g., mitotic recombination), which results in new genetic variation. Lichenized fungi possess the full complement of reproductive processes present in their non-lichenized relatives but with further embellishment as a result of obligate symbiosis with algae and other organisms. Therefore, lichens serve as an excellent model system in reproductive biology, but no study has yet tested the commonly held assumption that lichen mycelia are haploid. We present new whole genome assemblies from seven unrelated lichens and use allelic ratio frequencies to estimate ploidy. Of these seven, three were derived from multispore mycelial cultures and the remaining four were derived from intact lichen thalli (i.e., from metagenomic reads). Data from the metagenome samples indicate that two are likely haploid or highly homozygous diploid as a result of c...