SPLAYED, a novel SWI/SNF ATPase homolog, controls reproductive development in Arabidopsis

Background: The plant-specific transcriptional activator LEAFY (LFY) is a central regulator of the transition to reproductive development in Arabidopsis. LFY has a second, later role in the induction of floral homeotic gene expression. Available data suggests that, while LFY activity is controlled via interaction with tissue-specific coactivators, other mechanisms exist that regulate LFY activity, the identity of which are not known. Results: We have identified a novel component in the temporal control of the switch from vegetative to reproductive development in Arabidopsis thaliana. The SPLAYED (SYD) gene product acts with LFY to regulate shoot apical meristem identity. SYD is also involved in the regulation of floral homeotic gene expression. In addition, mutations in SYD cause LFY-independent phenotypes that indicate that SYD is necessary for meristem maintenance during reproductive development and that SYD is required for proper carpel and ovule development. SYD encodes a presumptive Arabidopsis homolog of the yeast Snf2p ATPase, which is implicated in transcriptional control via chromatin remodeling. Conclusions: SYD acts as a LFY-dependent repressor of the meristem identity switch in the floral transition, most likely by altering the activity of the LFY transcription factor. That SYD regulates flowering in response to environmental stimuli suggests that the effect of environmental cues on plant development may be achieved in part by regulating transcription factor activity via alteration of the chromatin state.