Coupland: Deciphering the role of the miRNA156/SPL15 module in the control of floral transition and inflorescence development in Arabidopsis
This project will be supervised by George Coupland at the Max Planck Institute for Plant Breeding Research
Timing reproduction is key to the evolutionary success of all organisms. In plants, diverse environmental and internal cues are integrated at the shoot apical meristem to control the timing of flowering and thus reproduction. After floral induction of Arabidopsis thaliana, the shoot apical meristem first produces small leaves with inflorescence branches in their axils, and later forms single flowers. This combination of structures generates the characteristic inflorescence morphology of this species. We showed that two genetically separable regulatory pathways act at the shoot meristem to initiate the formation of the inflorescence, and that these pathways act in different environments. One pathway promotes flowering of young plants and involves the florigen FLOWERING LOCUS T (FT) protein and its interacting transcription factor FD. The other pathway promotes flowering relatively slowly in winter conditions of low temperatures and short-day lengths and involves a regulatory module containing microRNA156 (miR156) and its target the SPL15 transcription factor. We found that in the absence of FT, SPL15 can efficiently activate the first stage of inflorescence development and produce inflorescence branches, but that it requires FT activity to induce the second stage and form flowers. Therefore, these two pathways have separable and interacting activities. This project aims to define the gene regulatory network controlled by the miR156/SPL15 module in promoting inflorescence development, a function which appears to be widely conserved in Angiosperms and Gymnosperms, and its interaction with FT to induce floral development. It makes use of unique genetic material that we have generated and the methods of confocal imaging, RNA sequencing and CRISPR-mediated reverse genetics.
Group homepage: https://www.mpipz.mpg.de/coupland
Key publication: Hyun, Y., Vincent, C., Tilmes, V., Bergonzi, S., Kiefer, C., Richter, R., Martinez-Gallegos, R., Severing, E., and Coupland, G. (2019). A regulatory circuit conferring varied flowering response to cold in annual and perennial plants. Science 363, 409-412. doi: https://doi.org/10.1126/science.aau8197