XVI International Botanical Congess

We illustrate the power of working on close relatives of model systems by studying inflorescence evolution in Brassicaceae and stamen number evolution in Antirrhineae (Scrophulariaceae). A few Brassicaceae produce flowers in the axils of rosette leaves. In one rosette-flowering species, violet cress (Jonopsidium acaule), the floral meristem identity gene, LEAFY, shows an expanded expression zone relative to Arabidopsis. A change in the regulation of LEAFY could explain the lack of supression of the subtending leaf. In Antirrhineae, the genus Mohavea differs from Antirrhinum in that three (rather than one) adaxial stamens abort during development. Given the demonstrated role of CYC in stamen abortion in Antirrhinum, a plausible, testable hypothesis is that the additional stamen abortion in Mohavea is due to an expanded domain of CYC activity.