Abstract
Leaves in angiosperms generally show flattened structure, of which formation depends on the leaf adaxial-abaxial polarity. On the other hand, many unifacial leaf species develop flattened leaf blades, even though they lack leaf adaxial-abaxial polarity. Thus, laminar outgrowth in unifacial leaves is regulated by a mechanism independent of the leaf adaxial-abaxial polarity.
To reveal the genetic mechanism of laminar outgrowth in unifacial leaves, we performed comparative analysis using closely related species in the genus Juncus: J. prismatocapus with flattened unifacial leaves and J. wallichianus with radialized unifacial leaves. We identified genetic factors involved in the laminar outgrowth in unifacial leaves by gene expression studies, and examined genetic linkage of them with blade flatness using inter-specific hybrids and its descendants. In addition, we studied genetic relationships between them using mutants of J. prismatocarpus with radialized leaf phenotype. In this report, we propose a genetic model underlying the laminar outgrowth in unifacial leaves with implications in the control of leaf central-marginal polarity specification.
