Abstract
Leaves are flat and lateral organs and developed from shoot apical meristem along three axes: the proximal-distal, medial-lateral and adaxial-abaxial axes. Mutations in the ASYMMETRIC LEAVES2 (AS2) gene of Arabidopsis result in various defects in the establishment of all three axes. To understand molecular roles of AS2, we have isolated and characterized mutants that enhanced as2 abnormalities. Mutation #16 generated filamentous leaves in the as2 background and pointed leaves in the wild-type background. The gene corresponding to #16 was predicted to encode a protein, which might function in processing of pre-ribosomal RNA. Pre-rRNA in fact accumulated in the #16 mutant. These results suggest the genetic interaction between an AS2 pathway and the processing of pre-rRNA in the polarity determination of leaves. The rid2 mutation, which results in defects in the in vitro regeneration potential of roots at high temperature, also encodes a protein having a role in processing of pre-rRNA. We currently examine effects of rid2 on the leaf polarity in the as2 background. We will present results of experiments with rid2 and discuss a genetic relationship between RID2 and AS2.
