All together now: Cellular and molecular aspects of leaf development in lycophytes, ferns, and seed plants

Recent advances in plant developmental genetics together with rapid accumulation of transcriptomic data on plants from divergent lineages provide an exciting opportunity to explore the evolution morphology. To understand leaf origin sporophytes land plants, we have combined available molecular and structural development leaves different morphologies lineages: clubmosses, spikemosses, leptosporangiate ferns, ophioglossioid marattioid whisk horsetails, conifers. Specifically, address peculiarities proximo-distal, ad/abaxial, lateral development; presence/absence mesophyll differentiation into palisade spongy parenchyma; type vascular bundles (collateral bicollateral). Furthermore, taxon-specific morphology-specific features are considered context organization shoot apical meristems (SAMs)—monoplex, simplex, or duplex—that produce primordia. The imply that cellular patterns initiation correlate strongly structure SAMs but not further later stages neither correlated SAM nor taxonomy. Occurrence and, if available, expression homologs angiosperm genes responsible for adaxial ( ARP C3HDZ ) abaxial YABBY KANADI domains, establishment marginal meristem WOX discussed. We show there is no correlation set TFs regulate domain between containing only (of most conifers), differentiated Ginkgo , Gnetum angiosperms). Expression three out four regulators primordia both sporangia— spikemosses clubmosses horsetails—indicates a sporangium program could been co-opted as “precursor program” microphylls euphylls. Additionally, ), ferns horsetails indicates at least some mechanisms regulation were well pre-program precursors.