Abstract
In higher plants, nearly all above ground part is derived from the shoot apical meristem (SAM). We isolated the recessive mutant gorgon (gor), which exhibits drastic expansion of the SAM, in Arabidopsis thaliana. In gor, the expansion of the SAM is already apparent in young seedlings. As the plant starts bolting, the SAM of gor continues to expand and produces numerous pin-shaped protrusions from its periphery but no branches or flowers. Shortly after, the SAM terminates by producing numerous flowers or branches from its entire surface. Moreover, some of these flowers produce extra flowers or floral organs from an additional whorl inside carpels. These observations show that gor is defective in the regulation of SAM size and floral organ development. We are now characterizing the gor phenotype in detail using molecular markers and map-based cloning of the mutated gene is in progress. Results of these experiments will also be presented.
