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As every gardener knows, annual plants flower only once during their life cycle, and need to be replaced each year. Perennials, on the other hand, can flower many times, cycling between flowering and vegetative growth for many years, in time with the changing seasons. Although flowering in annuals has been extensively studied using the model plant Arabidopsis thaliana (thale cress), few studies have looked at the regulation of flowering in perennials. Maria Albani, a postdoc at the Max Planck Institute for Plant Breeding Research in Cologne, Germany, and her colleagues looked for genes that regulate perennial growth in Arabis alpina (alpine rock cress), a perennial relative of Arabidopsis thaliana that grows in mountainous regions. They identified a gene, PEP1, that controls flowering in response to low temperatures — ensuring flowering in the spring — and that also restricts the duration of the flowering season and enables the return to vegetative growth every year (see page 423). Albani tells Nature about the significance of this gene.

What drew you to this topic?

I'm interested in flowering in perennials — annuals die after flowering but perennials somehow find a way to trick the whole plant-senescence programme and keep growing vegetatively. This is one of the first studies to focus on the molecular mechanisms of flowering in perennials. We hope that Arabis alpina becomes the lab plant of choice for studying perennials, as Arabidopsis thaliana has for annuals.

Did you encounter any challenges along the way?

We began from zero. When we started, nothing was known about the way Arabis alpina grows, flowers or manages to be a perennial. On top of that, the plant's life cycle slowed down our experiments. It took at least four months from the time we planted the seeds for flowers to bloom. We had to do many experiments in parallel because it would have taken too long to wait for one experiment to end before starting the next.

Does your finding have practical applications?

The fact that PEP1 affects the duration of a plant's flowering season is very important. Many fruit crops — for example, apples and grapes — are perennials. If we can understand how Arabis alpina cycles between flowering and vegetative growth every year, it will help us to understand how other perennials go through similar cycles. However, PEP1 has mainly been found in species closely related to our model plant — not in fruits — and practical applications will require more extensive research.