0.0025±0.0006 mutation/site/replication cycle
||Chrysanthemum chlorotic mottle viroid
||Gago S, Elena SF, Flores R, Sanjuán R. Extremely high mutation rate of a hammerhead viroid. Science. 2009 Mar 6 323(5919):1308. doi: 10.1126/science.1169202. abstract & p.1308 left column 2nd paragraphPubMed ID19265013
||p.1308 left column top paragraph:"[Investigators] estimated the mutation rate of Chrysanthemum chlorotic mottle viroid (CChMVd), a 399-nucleotide chloroplastic viroid with hammerhead ribozymes. Hammerheads are RNA motifs formed by three double-helix regions flanking a core of 15 highly conserved nucleotides critical for catalytic activity (ref 5), which mediate self-cleavage of replicative intermediates and, hence, are essential for viroid replication." p.1308 left column 2nd paragraph:"… [investigators] inoculated plants with an in vitro transcript of CChMVd (ref 7), and at the onset of symptoms [they] screened for mutations at the 15 core nucleotides plus the nucleotide preceding the self-cleavage site in each of the two hammerheads (32 sites). Considering that these mutations are lethal for the viroid, their population frequency must equal the mutation rate because, despite multiple replication rounds downstream from inoculation, they have necessarily been generated during the last one."
||p.1308 left column 2nd paragraph:"In three independent experiments, [investigators] found three, seven, and five mutations in 63, 64 and 61 reverse transcription polymerase chain reaction (RT-PCR) clones, respectively (188 ×32=6016 total target sites), yielding a mutation rate of 0.0025±0.0006 (SEM) per site and replication cycle, that is, one mutation per 400 nucleotides (fig. S1)."