Mitochondrial DNAs of Suillus: Three fold size change
in molecules that share a common gene order.
Bruns, T D; Palmer, J D; Shumard, D S; Grossman, L I; Hudspeth, M
Department of Botany, University of California
Current Genetics. 1988 13(1):49-56.
We constructed restriction-site and gene maps for mitochondrial DNAs
from seven isolates of five species of Suillus (Boletaceae,
Basidiomycotina). Each mitochondrial genome exists as a single circular
chromosome, ranging in size from 36 to 121 kb. Comparisons within
species and between two closely related species revealed that
insertions and deletions are the major form of genome change,
whereas most restriction sites are conserved. Among more distantly
related species, size and restriction-site differences were too great
to allow precise alignments of maps, but small clusters of putatively
homologous restiction sites were found. Two mitochondrial gene orders
exist in the five species. These orders differ only by the relative
positions of the genes for ATPase subunit 9 and the small ribosomal
RNA and are interconvertible by a single transposition. One of the
two gene arrangements is shared by four species whose mitochondrial
DNAs span the entire size range of 36 to 121 kb. The conservation
of gene order in molecules that vary over three-fold in size
and share few restriction sites demonstrates a low frequency of
rearrangements relative to insertions, deletions and base substitutions.