Figure 2.

Many Introns in the Cucumber Mitochondrial Genome Are Substantially Larger Than Homologous Introns in Other Seed Plants.

Mean (±sd) intron lengths were calculated from the set of fully sequenced mitochondrial genomes (except cucumber) (n = 20) for all but the cox1 group I intron, which among the fully sequenced genomes, is present only in watermelon and cucumber. Mean length of the cox1 intron therefore was based on full-length intron sequences in the alignment used by Sanchez-Puerta et al. (2008). Intron sizes for two other cucurbits (Cucurbita [zucchini] and Citrullus [watermelon]) and their phylogenetic relationships to cucumber (Cucumis) are shown to highlight the recency of intron expansions in cucumber. Introns are sequentially numbered beginning from the 5′ end of the gene, and trans-spliced introns in cucumber are marked with an asterisk. Not included are the two introns in the cox2 gene that are widely present in angiosperms (Qiu et al., 1998) but absent from cucumber.

[See online article for color version of this figure.]