The complete plastome of the coccoid green alga Jenufa minuta (Chlorophyceae, incertae sedis) unveils a noncanonical genetic code and a previously unrecognized trans-spliced group II intron in the rpl32 gene

Abstract

We describe the plastome of Jenufa minuta, a unicellular green alga whose precise relationship with the Sphaeropleales (Chlorophyceae) remains uncertain. This 206,680-bp genome contains 100 conserved genes, 11 of which exhibit 16 group I and seven group II introns. We discovered a trans-spliced group II intron in the rpl32 gene of J. minuta and its orthologs in all Sphaeropleales and several Chlamydomonadales; this is the first time this intron is documented. As in the mitochondria of J. minuta, the UGA codon is decoded as tryptophan. To our knowledge, this is the second report of a variant genetic code in plastids.

Keywords

• noncanonical genetic code
• sphaeropleales
• trans-spliced group ii intron
• uga codon reassignment