The Fate of Inflorescence Meristems I s Controlled by Developing Fruits in Arabidopsis ' linda 1

The relationship between fruit development and the proliferative capacities of inflorescence meristems has been examined in Arabidopsis fhaliana. In the wild-type Landsberg erecta (Ler) line, flower production ceases coordinately on all inflorescence branches by a process we have designated global proliferative arrest (CPA). Morphological studies indicate that CPA involves a cessation of proliferative activity at the meristems, but a retention of the structural characteristics of the proliferating meristems. CPA does not occur in the male-sterile (msl-7) line, nor in wild-type Ler when fruits are surgically removed. In these cases, inflorescence meristems continue to proliferate, ultimately terminating by a different process, designated terminal differentiation, in which disruptions in patterning at the apex are followed by the loss of the inflorescence meristem. We present an argument that CPA is mediated by a specific communication system between inflorescence meristems and developing fruits. Analysis of reduced-fertility mutants provided evidence that CPA is dependent on seed development specifically. Mutations conferring hormone deficiency or insensitivity did not disrupt the correlative interactions leading to CPA.