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. Especially, the establishment of adaxial-abaxial axis in leaf primordia is important for flat leaf and the defects of this step result in abnormal filamentous and/or trumpet-like leaves. ASYMMETRIC LEAVES2 (AS2) gene encodes a plant specific protein and is involved in the establishment of all three axes. To understand the molecular function of the AS2 and obtain novel factors involved in the establishment of adaxial-abaxial axis, we performed screening of as2 modifiers and obtained several mutants that generate filamentous and trumpet-like leaves in as2 background. A double mutant of the as2 and a mutant of a DEAD box RNA helicase that is involved in the processing of pre-rRNA frequently generated the abaxialized filamentous leaves at high temperature. . A double mutant of as2 and another pre-rRNA processing factor also showed similar morphological abnormality. These results suggest the importance of the precise pre-rRNA processing in the establishment of adaxial-abaxial axis in leaf primordia.
