Move over petunias, roses, lilies, roses, lavenders, and moonflowers. If you like roses specifically, forget about choosing between red, yellow, pink, or white. There’s more coming to your garden that is unlike anything you're currently familiar with: flowers that change color. Not just once or over weeks, but daily. Imagine petunias that change color throughout the day. Or flowers that are purple on your kitchen table and turn pink when kept outside. As it turns out, it is more a real possibility now than science fiction.

Keira Havens and Nikolai Braun of Revolution Bioengineering (RevBio) are bringing this biological artistry to life. The duo is based in Ireland and working to make the emerging field of synthetic biology more attractive and less fear-invoking. They are funded by the Synbio axlr8r, now Indie.Bio, an accelerator program based in University College Cork. The funding is just enough to get them through to proof-of-concept. The startup is looking for other funding avenues to be able to sell its flowers. So, what kind of flowers are we looking at?

Blue, pink, or do you fancy both colors in the same flower? Image source: RevBio.

The science behind color changing flowers

RevBio is tinkering with Petunia to develop flowers that change color from red to blue and then back to red, within a day. It is making use of two features in plant biology. First, small molecules called anthocyanins that are responsible for the color in flowers. Second, there is an internal clock in plants (also found in animals and fungi) that tracks exposure to sunlight and is self-sustained based on cues from the environment. Together, these biological mechanisms drive the novelty behind RevBio’s flowers.

Anthocyanins are pigments that are responsible for the reds, purples, and blues in plant tissues, particularly the flowers. Plants synthesize them to attract pollinators, but humans have developed a profound liking for their aesthetic value. Like any other biological molecule, their properties change as their environment changes. In the case of anthocyanins, it is the change in color. Presence of metal ions, change in the pH, or interference by some other metabolite are some environmental cues that can alter anthocyanins and change the flower color.

A popular example are hydrangeas. They are pink when grown on acidic soil (sprinkle some lime) and blue when grown on basic soil (a tablet of aluminium sulfate mixed in water or steel wool buried under the bushes would do the trick). The science to make the color change with time is a bit more complex.

Another interesting aspect is the presence of an internal clock in plants. Circadian rhythms occur as a plant attunes itself to the periodic changes in light availability. This clock regulates expression of different genes throughout the day in a cyclic fashion. The plants use it to start photosynthesis when the sun comes up in the morning or to release fragrance in the evening.

In Petunia circadia, as RevBio fancies calling its flowers, the internal clock is connected to the anthocyanin production pathway to enable flowers to exhibit different colours at different times of the day. RevBio has successfully tested the connection in bacteria and is currently working on protoplasts (single, isolated plant cells) to insert the functionality in plants. As it turns out, it isn’t the only synthetic biology project concerned with beautiful plants to have captured the public’s imagination in recent years.

Nikolai Braun, Chief Scientific Officer, at work. Image source: RevBio.

Another beautiful plant

The Glowing Plant project was the first time crowdfunding was used to generate funds for a synthetic biology application. Its Kickstarter managed to raise a whooping $484,000 on the promise of a plant -- Arabidopsis thaliana, more the favorite of a scientist than a hobbyist gardener -- that glows in the dark. The seeds are estimated to be shipped later this year.

Though the science for the project has been in place since the 1980’s, it stirred a lot of controversy and discussion over public opinions on synthetic biology -- something that turned out well for the field. However, it still begs the question: “Why is a technology long reserved for curing diseases, producing food, or generating power being used for purposes like glowing plants or color-changing flowers?”

Visualizing synthetic biology

The prices of gene sequencing and synthesis have dropped considerably, allowing such projects to be feasible. Glowing Plant, for instance, is one of the first biotech ventures to have been funded by Y Combinator. In addition, these projects should be done to dispel the fears associated with GM and synthetic organisms. “When you tell people that genetic engineering can be used to fight hunger by increasing vitamin content and reducing crop loss to insects”, says Pam Ronald, professor at UC Davis, “sometimes it just doesn’t register”. But, when people can visualize the beauty of these products, they realize that the GMOs are not as scary as are often projected.

By the end of the decade, your local florist might be selling plants produced from RevBio, Glowing Plant, or another team of garage biohackers. While initial products are more novelty than functional, future household plants could clean the air in your home or provide a steady stream of fragrances. The question is -- and the future of synthetic biology consumer products may depend on the answer -- will you buy them? If the successful Kickstarter project serves as any glimpse into consumer appetites, then the answer may be a resounding “yes”.