Abstract
Leaves in angiosperms generally show flattened morphology, which is established depending on the adaxial(Ad)/abaxial(Ab) identities of leaves. By contrast in unifacial leaves, some species develop flattened leaf blades, even though their leaf blades consist of only the Ab side. Thus, laminar outgrowth in unifacial leaves is regulated by a mechanism independent of the leaf Ad/Ab identities. To reveal the mechanism, we have adopted comparative analyses using closely related two species in Juncaceae, J. prismatocarpus and J. wallichianus, which exhibit flattened and radialized leaf blades, respectively.
In this study, we found that treatment of developing J. prismatocarpus seedlings with either exogenous auxin or auxin transport inhibitors eliminated flatness of leaf blades, leading them to radialized morphology. These treatments did not affect radialized leaf blades in J. wallichianus. Thus, we suggest that presumptive auxin gradient within leaves is necessary to promote the laminar outgrowth in unifacial leaves. We will discuss relationship of auxin gradient with expressions of the putative genetic factors, which are responsible for the laminar outgrowth in unifacial leaves.
