Abstract
During embryogenesis, apical meristems (shoot and root apical meristem) are formed based on the basic pattarn, and regionalitation. To investigate the mechanism of the apical meristem formation, we have isolated several rice embryogenesis mutants, which defect in the organ formation. These organless mutants may be classified into two types, that is, defect in the mechanism of organ formation itself or in basic pattern formation. Based on the expression pattern of molecular markers (OSH1 and OsSCR), we focused on one organless mutant, orl1, because these markers were expressed normally and therefore orl1 belongs to the latter-type mutant. orl1 can form regenerate plants, which showed abnormal phenotypes in leaf, flower, and root. The ORL1 gene encoded a homologous protein to anthranilate synthase β-subunit, which involved in the tryptophan biosynthesis. Now, we are investigating a possibility that orl1 is defected in biosynthesis of IAA, which is produced from tryptophan as a precursor.
