699 / 2019-05-01 18:27:18

Distinctive role of FLM-β and FLM-δ on SVP function in ambient temperature-responsive flowering

SVP, Flowering, Transcription factor

Growth and Development > Growth and Development

SHORT VEGETATIVE PHASE (SVP), a MADS-box protein that acts as a transcriptional repressor, is a main component of ambient temperature-responsive flowering. SVP associates with other transcription factors to form a high-order regulatory complex. The most well-known co-factor of SVP is FLOWERING LOCUS M (FLM), which produces various splicing variants, depending on temperature changes. We previously revealed that SVP protein is unstable at high temperatures, leading to less abundant repressor complex with FLM-β.
Here, we further investigated the temperature sensing mechanism modulated by SVP and FLM proteins. We found that SVP translocation varied depending on temperature changes and the presence of different FLM isoforms. SVP localized in the nucleus at low temperatures, whereas abundant SVP proteins were found in the cytoplasmic region at high temperatures. Interestingly, SVP localization was limited to the cytoplasm in the absence of FLM and the nuclear localization of SVP was recovered by co-expression of SVP with FLM-β. In contrast, over-expression of FLM-δ accelerated SVP degradation at high temperatures. Furthermore, microscale thermophoresis analyses revealed that FLM-β strongly binds to SVP at low temperature, while FLM-δ strongly binds to SVP at high temperature. Taken together, we suggested that the interaction with FLM-β is important for SVP nuclear translocation at low temperatures and the association with FLM-δ makes SVP unstable at high temperatures