What is the model for floral induction by daylengthSolutionB

What is the model for floral induction by day-length?

Solution

Basically there are Long day plants and Short day plants. In both of these types the alternate day and night duration is important for flowering. A research on Effect of photoperiodism on flowering in Arabidopsis, (a long day plant) has revealed the role of many genes involved in the process. The Flowering is promoted by a promoter gene Constans (CO), which in turn regulates the level of FT mRNA acumulation.

Photoreceptor(FKF1) ---> Flowering promoter(CO) -----> Expression of florigen

In short day plants flowering can be induced by AP1 gene only. In rice the flowering depends on two genes: One promoter(Ehd1) and other repressor(Ghd7). Promoter expresses florigen.

Floral induction starts when there occurs a transition from vegetative to reproductive phase and a signal is passed when there is formation of floral meristem from stem. It starts the functioning of many genes who carry out this process further. At an early stage CO gene is induced. Duration of day light affects CO locus. CO in turn initiates production of FT protein responsible for flowering induction. Longer day length regulates increased CO synthesis and also regulates genes like AG and LFY which express A, B, C genes FT protein is linked to FD protein in shoot apex which induces flowering.