Figure 5.

The trans-splicing group I intron cox1i1305 in I. engelmannii. The ribozymic core in the 5′-half (paired regions P1–P8) is conserved with the cis-arranged orthologue in Marchantia polymorpha. Italic letters indicate flanking exon sequences, bold letters indicate nucleotide identities in Marchantia, non-bold letters indicate transitions, lower case letters indicate transversions and numbers indicate loop sizes L2, L5, L6 and L8 in Isoetes and Marchantia (after the oblique), respectively. The intron discontinuity in Isoetes coincides with rearrangements in P9 which embraces a large continuous L9 loop of 800-nt in Marchantia (dotted line, blue). The Marchantia orthologue carries only traces of a formerly functional intron-encoded ORF. A C-to-U RNA editing event in the upstream exon is shown, three further cytidines in the intron core may likewise be subject to editings which could improve conservation of base-pairings.