The induction of flowering is a central event in the life cycle of plants. When timed correctly, it helps to ensure reproductive success, and therefore has adaptive value. Because of its importance, flowering is under the control of a complex genetic circuitry that integrates environmental and endogenous signals.
Genetic analyses initially suggested the existence of distinct, genetically defined pathways that regulate flowering in response to a specific input. Over the last years, however, it has become apparent that many important flowering time genes are not regulated by single inputs, but rather integrate multiple, often contradictory signals to control the induction of flowering. This provides plants with a certain developmental plasticity in their timing of the floral transition.
Figure 1: Genetic network regulating the expression of the FLOWERING LOCUS T (FT) gene in the leaf vasculature. The FT protein serves as a florigen, a long-distance signal that moves to the growing tip of the plant, the so-called shoot apical meristem, where it induces the formation of flowers.Work in our group has so far mostly aimed to understand the precise mechanisms that govern flowering time. To this end we employ a combination of molecular biology, genetic, and high-throughput sequencing (ChIP-seq, RNA-seq) techniques to unravel the transcription factor network that integrates diverse environmental signals in the model plant Arabidopsis thaliana. More recently we have adopted the INTACT, which allows the isolation of nuclei from defined tissues and cell types, to increase the temporal and spatial resolution of our analyses (Fig. 2). A second focus of the group is directed at understanding how trehalose-6-phosphate (and sugar signals in general) are integrated into the canonical network that regulates flowering.
Figure 2: Establishing INTACT for the shoot apical meristem (SAM) of Arabidopsis thaliana. (A) During the transition to flowering the SAM undergoes a transition and starts producing flower primordial instead of leaves. (B) We have established INTACT (Deal & Henikoff, Dev. Cell, 2010) for the SAM to study the transcriptional and epigenetic process that control flowering in this important tissue
Key Publications
- Posé D, Verhage L, Ott F, Yant L, Mathieu J, Angenent GC, Immink RGH and Schmid M (2013). Temperature-dependent regulation of flowering by antagonistic FLM variants. Nature 503: 414-417.
- Wahl V, Ponnu P, Schlereth A, Arrivault S, Langenecker T, Franke A, Feil R, Lunn JE, Stitt M and Schmid M (2013). Regulation of flowering by trehalose-6-phosphate signaling in Arabidopsis thaliana. Science 339: 704-707.
- Galvão V, Horrer D, Küttner F and Schmid M (2012). Spatial control of flowering by DELLA proteins in Arabidopsis thaliana. Development 139: 4072-4082.
- Yant LJ, Mathieu J, Dinh TT, Ott F, Lanz C, Wollmann H, Chen X and Schmid M (2010). Orchestration of the floral transition and floral development in Arabidopsis by the bifunctional transcription factor APETALA2. Plant Cell 22: 2156-2170.
- Mathieu J, Yant LJ, Mürdter F, Küttner F and Schmid M (2009). Repression of flowering by the miR172 target SMZ. PLoS Biology 7: e1000148.
- Mathieu J, Warthmann N, Küttner F and Schmid M (2007). Export of FT protein from phloem companion cells is sufficient for floral induction in Arabidopsis. Current Biology 17: 1055-1060.