Abstract
The evolution of the carpel, the defining feature of angiosperms, remains a fundamental question in plant biology. Understanding how this organ originated is crucial because it underpins the reproductive success and diversity of flowering plants. Here, we investigated the functional conservation between gymnosperms and angiosperms of key transcription factors involved in carpel development. We found that Ginkgo biloba homologs can functionally substitute for their angiosperm counterparts in stigma development. We discovered that GbRAV5 is related to angiosperm NGA genes, challenging previous notions that these are exclusive to angiosperms, and we found a parallel loss of the AP2 domain in gymnosperms providing a rare snapshot of how protein families evolve. Conserved protein interactions and overlapping expression patterns of GbRAV5 and GbHEC in Ginkgo ovules suggest that the molecular toolkit for carpel development was largely present in the last common ancestor of seed plants, offering new insights into the evolution of reproductive structures.