RAGGED SEEDLING2 is required for expression of KANADI2 and REVOLUTA homologues in the maize shoot apex.

The anatomy of ragged seedling2-R (rgd2-R) leaves is disorganized along the adaxial/abaxial axis. Mutant leaves often exhibit radial morphology but unlike similar mutants, rgd2-R radial leaves have no reduction of adaxial or abaxial identity. Previously, we proposed that RGD2 does not establish adaxial or abaxial fate but performs a signaling function during primordial leaf development. Here we describe genetic and molecular tests of our model for RGD2 function. Genetic analyses explored the phenotypic effects of rgd2-R on maize leaf mutations disrupting mediolateral and/or dorsiventral development. In situ hybridization and qRT-PCR analyses reveal that rgd2-R mutants show reduced accumulation of adaxial and abaxial molecular markers in the maize shoot apex. These data contribute to a revised model whereby RGD2 is required for normal accumulation of leaf patterning transcripts in the developing shoot. Molecular and genetic analyses suggest that RGD2 and LEAF BLADELESS1 share overlapping functions affecting shoot development in maize. Copyright 2006 Wiley-Liss, Inc.