Inflorescence commitment and architecture in Arabidopsis.

Flowering plants exhibit one of two types of inflorescence architecture: indeterminate, in which the inflorescence grows indefinitely, or determinate, in which a terminal flower is produced. The indeterminate condition is thought to have evolved from the determinate many times, independently. In two mutants in distantly related species, terminal flower 1 in Arabidopsis and centroradialis in Antirrhinum, inflorescences that are normally indeterminate are converted to a determinate architecture. The Antirrhinum gene CENTRORADIALIS (CEN) and the Arabidopsis gene TERMINAL FLOWER 1 (TFL1) were shown to be homologous, which suggests that a common mechanism underlies indeterminacy in these plants. However, unlike CEN, TFL1 is also expressed during the vegetative phase, where it delays the commitment to inflorescence development and thus affects the timing of the formation of the inflorescence meristem as well as its identity.