Floral repressors in Arabidopsis thaliana

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Floral induction has been studied extensively in Arabidopsis thaliana. Over the last decade, tremendous progress has been made in understanding this important developmental process, and many genes promoting flowering have been isolated. Floral repression, however, is less well understood. Similarly, it has been unclear how output of different floral induction pathways controls the expression of genes that control the identity of individual flowers. We have identified a floral repressor, SCHLAFMÜTZE (SMZ), which encodes an AP2-type transcription factor that acts downstream in the photoperiod pathway. SMZ and the paralogous gene SCHNARCHZAPFEN (SNZ) belong to a clade of six AP2-family members that are potential targets of miR172 micro-RNAs. We will study in detail how transcript accumulation of SMZ and SNZ is regulated, including the potential role of miR172 in this process. Transcriptional targets of SMZ and SNZ will be identified using expression profiling as well as genome-wide identification of SMZ/SNZ bindigs sites. Molecular, biochemical and genomic approaches will be complemented by genetic studies, including mutagenesis screens to identify enhancers and/or suppressors of an SMZ gain-of-function allele. Finally, we will begin to characterize seven additional activation-tagged lines in which flowering is delayed, and which are therefore candidates for identifying additional floral repressors.