Flowering Hormone Florigen Also Triggers Tuber Formation in Potatoes

Grumpy potatoFlorigen = Tuberigen

In an online report (ref 1 below) published this week in Nature, researchers in Spain and Japan have provided evidence that a protein similar to FT, currently regarded as the flowering signal florigen in plants, not only initiates flowering in potatoes, but also triggers tuber formation.

“Seasonal fluctuations in day length regulate important aspects of plant development such as the flowering transition or, in potato (Solanum tuberosum), the formation of tubers. Day length is sensed by the leaves, which produce a mobile signal transported to the shoot apex or underground stems to induce a flowering transition or, respectively, a tuberization transition.” (from ref. 1 below)

As previously discussed here and here, much has been learned about the flowering signal in plants over the past few years.

Briefly, plants that form flowers in response to a particular photoperiod sensed by the leaves produce a flower-initiation signal in the leaves.

This signal, named florigen nearly 100 years ago, travels from the leaves to the shoot apical meristem where it triggers genes that initiates flower formation. (For lots more about this story, please see here.)

Until recently, the identity of florigen was unknown.

Most plant scientists now agree that florigen is a protein named FT (coded for by gene named “Flowering Locus T”). Its analog in rice is called Hd3a.

Interestingly, the onset of tuber formation in potatoes is also sensitive to the photoperiod. (Most potato varieties are “long-night plants”, that is, tuber formation is induced by relatively long nights, uninterrupted by light.)

It’s long been suspected by scientists that study potatoes that florigen and “tuberigen” were likely one in the same signal (see, for example, ref. 2 below).

Indeed, interspecific grafting experiments demonstrated that the flower-inducing (florigen) and tuber- inducing (tuberigen) signals were functionally exchangeable.

So, perhaps it not so surprising that an analog to FT in potato may induce tuber formation as well as flowering.

References

1. Navarro, C., J. A. Abelenda, E. Cruz-Oro, C. A. Cuellar, S. Tamaki, J. Silva, K. Shimamoto, and S. Prat (2011) “Control of flowering and storage organ formation in potato by FLOWERING LOCUS T.” Nature, Vol. 478, pp. 119-122. (Abstract)

2. Jackson, S. D. (1999) “Multiple signalling pathways control tuber induction in potato.” Plant Physiology, Vol. 119, pp. 1–8. (Full Text)

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