Abstract
Organ regeneration in tissue culture involves de novo formation of apical meristems, which should provide a useful system to study how meristems arise. We isolated a number of temperature-sensitive mutants of Arabidopsis with defects in organ regeneration. Of these, rid3 is characterized by the inability to form adventitious roots and shoots at the restrictive temperature. Our previous analysis revealed that the RID3 gene encodes a novel WD-40 repeat protein and that, in tissue culture, its expression increases during callus development and decreases locally before the formation of the shoot apical meristem. Here we report some recent results on the function of RID3 in embryogenesis. We found that the rid3 mutation interferes with embryonic pattern formation and with expression of meristem-related genes and that RID3 expression, which is uniformly high in early-stage embryos, is gradually excluded from pre-meristematic regions as embryogenesis proceeds. Our results indicate that RID3 is involved in the formation of apical meristems during embryogenesis as well as during organ regeneration.
