In: Biology
Scientist looked for the flowering hormone, which they named florigen for many years and finally have found it. What is florigen, i.e., what type of molecule? In what cells does it move throughout the plant? Does it act alone? (You do not need to know the detail but just the general concept of what happens in response to the correct environmental signal.)
Florigen is a protein - a mobile protein - which is encoded by the Florigen Locus T (FT) gene. This protein plays a very important role in plants in providing the flowering signal. There have been studies conducted which show that the gene encoding for the florigen protein is highly conserved across the flowering plants.
Generally, the florigen movement is seen in the phloem. For the production of the protein, the mRNA is synthesized in the companion cells found in the phloem of the flowering plant. This mRNA then moves to the shoot apex where it stimulates flowering of the plants.
The florigen molecule does not act alone. It acts in conjunction with Flowering Locus D (FD), a transcription factor, (after translocation of florigen to the nucleus) forming a heterodimer and activating the gene APETALA1 (AP1) present at the meristem. The AP1 gene is required for the normal development of sepals and petals. The complex is of florigen, FD and AP1 are known as Florigen Activation Complex (FAC) and this is responsible for the activation of flowering from the meristem.
(The apical meristem consists of undifferentiated tissue which can undergo cell division to form different plant parts).