Newly discovered signaling pathway ensures that plants remember to flower

Aug 20, 2009
Electron micrograph of the common wallcress, Arabidopsis thaliana. Image: Jürgen Berger

(PhysOrg.com) -- Why do some plants blossom even when days are short and gray? Scientists at the Max Planck Institute for Developmental Biology have found the answer to this question: An endogenous mechanism allows them to flower in the absence of external influences such as long days. A small piece of RNA, a so-called microRNA, has a central role in this process, as a decline of its concentration in the shoot apex triggers flowering.

MicroRNAs are very short RNA snippets that have emerged in recent years as essential regulators of gene function in both plants and animals. By binding to complementary motifs in a , they inhibit its translation into protein. This process thus blunts the activity of the corresponding gene.

In Tübingen, developmental biologists have discovered that the common wallcress, Arabidopsis, uses this to switch from vegetative to reproductive development. A group of related regulators, the SPL proteins, play an important role in promoting the onset of flowering. In young plants, production of SPL proteins is prevented by high levels of microRNA156.

Jia-Wei Wang and colleagues demonstrate that independent of external cues, the concentration of the microRNA declines over time, like sand running through an hourglass. When the concentration falls below a certain level, enough SPL proteins are produced to activate the flowering process even in the absence of other regulators that measure day length or external temperature. This in turns allows a sufficiently old plant to flower, even in an unfavorable environment.

Interestingly, the SPLs do double duty, since they have supporting roles when plants flower in response to long days. Furthermore, both the SPLs and other regulators eventually converge on a similar set of targets crucial for flowering.

"Flowering is crucial for the long-term survival of plants. The redundancy of environment-dependent and -independent mechanisms ensures that do not wait forever until flowering. Better flower once, then never", explains Detlef Weigel, director at the Max Planck Institute for Developmental Biology.

More information: Jia-Wei Wang, Benjamin Czech, Detlef Weigel; miR156-regulated SPL transcription factors define an endogenous flowering pathway in Arabidopsis thaliana; Cell, August 21, 2009; doi: 10.1016/j.cell.2009.06.014 .

Source: Max-Planck-Gesellschaft (news : web)

Explore further: Aging white lion euthanized at Ohio zoo

add to favorites email to friend print save as pdf

Related Stories

Formula discovered for longer plant life

Sep 23, 2008

(PhysOrg.com) -- Plants that grow more slowly stay fresh longer. In their study now published in PLoS Biology, scientists at the Max Planck Institute for Developmental Biology in Tübingen have shown that ...

Flowering Signal Found

Jun 09, 2007

The signal that causes plants to flower, or "florigen," has been identified by researchers at UC Davis, the University of Arizona, Tucson, and collaborators in New Zealand and Mexico.

Recommended for you

A vegetarian carnivorous plant

Dec 19, 2014

Carnivorous plants catch and digest tiny animals in order and derive benefits for their nutrition. Interestingly the trend towards vegetarianism seems to overcome carnivorous plants as well. The aquatic carnivorous bladderwort, ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.