Hothouse Flowers: Why Does A Warm Spring Promote Flowering?

Warming Temps –> “Fast-Forward” Flowering
Unusually warm temperatures often cause some plants to flower early.

For example, this spring in eastern North America unseasonably high temperatures have induced some plants to put flowering on “fast forward”.

Coincidentally, a recently-published research report (see Ref. 1 below) has revealed a genetic “switch” that may trigger the flowering process in some plants as temperatures increase. (An excellent description of this research and its potential implications can be found here.)

How does this so-called “genetic switch” work?

Simply put, it promotes the production of the flowering hormone called florigen, which triggers plants to make the transition from a vegetative state to a flowering state.

I won’t go into what florigen is and how it works here, because this has been discussed in several previous posts (see here, for example). (Or you can read all about it in my e-book “How Plants Make Flowers”.)

Suffice it to say that florigen is a protein produced in the leaves that travels via the phloem to the apical meristems where it activates genes involved in floral induction. (Florigen protein can do so because it is a transcription factor.)

A Genetic Thermostat For Flowering

This newly reported research indicates that warmer temperatures somehow induce the production of a protein called PIF4, which, in turn, promotes the production of florigen.

Apparently, the gene coding for PIF4 is only active when it is warm. So, when plants are competent to flower, and they experience unseasonably warm temperatures, PIF4 may likely be the primary reason that some plants will flower early.

Now, since we have better information about the genetics of how warm temperatures induce flowering, this may allow scientists to modify plants’ responses to temperature changes through genetic modification or plant breeding. Being able to do this may help produce crop plants that are more resilient when faced with unusually high temperatures likely to occur as a result of “global weirding”.

1. Kumar, S. V., et al. (2012) “Transcription factor PIF4 controls the thermosensory activation of flowering.” Nature, published online 21 March 2012. (Abstract)

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