Evolution of the molecular mechanisms controlling development of the reproductive structures of the gymnosperm Ginkgo biloba

Establishment of the seed was a key stage in the evolution of land plants. Pollination and fertilisation are fundamental processes in plant reproduction as they ensure seed production and ultimately propagation of the species. Most studies on the reproduction of seed-producing plants have been carried out by studying the flowers of model species, but for a better understanding of the evolution and molecular mechanisms regulating these processes, they must also be studied in gymnosperms, namely plants that produce seeds without genuine flowers. In the gymnosperm Ginkgo biloba, a characteristic tree with fan-shaped leaves that turn golden yellow before falling in autumn, pollination and fertilisation are separated in time, unlike in flowers, where the two processes occur one after the other. Male and female reproductive structures at different stages of development were collected from Ginkgo trees in the Botanical Garden of Padua. Using this material and advanced investigation techniques (RNAseq analysis, transcriptomics, metabolomics, various morphological approaches, in situ hybridisation), pollen development, pollen tube germination inside the ovule and, for the female counterpart, ovule development and fertilisation mechanisms were studied extensively. A description of the genes activated or suppressed at the crucial moment of pollination (D’Apice et al., 2021, New Phytol., 2353) and the molecular dialogue between sporophyte and female gametophyte (D’Apice et al., 2022, Am. J. Bot., 887) were recently published by the group, which coordinates an EU-funded project (MSCA-RISE EVOFRULAND) involving 13 other international research groups.