ASYMMETRIC LEAVES1 and ASYMMETRIC LEAVES2 proteins of Arabidopsis thaliana forms a protein complex that is involved in a symmetrical leaf development

Abstract

Plant leaves develop from a shoot apical meristem along three axes (adaxial-abaxial, proximal-distal, medial-lateral axes). The asymmetric leaves2 (as2) mutants generate leaf lobes and leaflet-like structures in bilaterally asymmetric manner. To understand the molecular mechanisms behind the leaf development, we have isolated the AS2 gene. AS2 encodes a novel protein involved in a gene family with 42 members in Arabidopsis. The N-teminal region of AS2 which contains C-motif (Cx2Cx6Cx3C) and leucine-zipper-like structure is conserved in all proteins encoded by this family. We designated it AS2 domain. The as1 mutant shows the phenotypes similar to those of as2. AS1 encodes a MYB related protein. Using immunoprecipitation experiments, we showed that AS1 and AS2 interact in vitro. Expression analysis showed that AS1 and AS2 are expressed in overlapping regions of the leaf primordia. Our results suggest that AS1 and AS2 forms protein complex, which may regulate an early stage of leaf development.