FIGURE 1.

Model of KAI2 and D14 evolution. KAI2 orthologs are present in charophyte algae and basal land plants. D14 likely arose by duplication of KAI2 prior to the evolution of spermatophytes. Although the timing of this duplication is uncertain, a potential D14 ortholog is present in Selaginella moellendorfii. We hypothesize that most spermatophyte KAI2 are KL and/or KAR receptors. In parasitic plants, KAI2 duplication and evolution have produced three clades. KAI2c is hypothesized to be KL-specific, KAI2i may be KAR-specific, and KAI2d are SL-responsive. Reprinted from Conn et al. (2015) with permission from AAAS.