Could glow-in-the-dark plants replace streetlights?

They say that mighty oaks from little acorns grow. Lighted oaks require a little help from science though.

The fluorescent marker research underlying the Glowing Plants initiative was pioneered by 2008 Nobel Prize winners Osamu Shimomura, Martin Chalfie and Roger Y. Tsien, but work on tracking gene expression using green fluorescent protein (GFP) really blossomed in the 1990s. The protein, which glows when exposed to ultraviolet light, soon initiated a sea change in molecular and cellular biology, medicine and pharmacology, and helped plant the seed for fledgling biotech industries such as biosensors and bioinformatics [sources: Evans; Lee and Min; Nobel Foundation; Timmer; Tsien].

But plants that require a black light to shine aren't much use for driving or reading. Such applications require a light-shedding chemical reaction, a kind of germinating glow stick.

In 1986, University of California at San Diego (UCSD) researchers created just that when they modified a tobacco plant to produce an enzyme called luciferase. As any firefly can tell you, when luciferase reacts with ATP, an energy-storing molecule used in metabolism, and luciferin, an organic molecule, it emits light [source: Monastersky].

UCSD's plant was limited in one important regard, however: It didn't make its own luciferin, so it was unable to, so to speak, glow it alone. In 2010, researchers at Stony Brook University overcame this limitation by slotting six luciferin-coding genes from bioluminescent marine bacteria into genetic material located in the plant's chloroplasts (plant structures that hold photosynthetic pigment). Et voila, autoluminescent tobacco -- presumably for recovering smokers who like to light up without lighting up [sources: Evans; Krichevsky et al.; Paramaguru; Pollack].

Unfortunately, the Stony Brook plant shone so dimly it required five minutes in darkness for human eyes to perceive it [source: Pollack]. Worse, the glow gradually self-destructed as the luciferin fueling it was converted into oxyluciferin [source: Swain].

One possible way out of this chemical cul-de-sac came in 2010, when a University of Cambridge iGEM team (see sidebar) inserted genes from fireflies and bioluminescent bacteria into modified E. coli, creating a process that recycles oxyluciferin back into its glow-friendly precursor. Their process also boosted light output sufficiently that a wine-bottle-sized bacterial culture emitted enough light to read by. Finally, Evans and company had the pieces they needed for a renewable and self-sustaining plant light [sources: Evans; iGEM; Swain; Timmer].

But whereas glowing markers encompass vital research and medical applications, the point of a glowing tree -- even one with potentially positive environmental effects, assuming Evans is right -- leaves many observers stumped.

However much or little Evans and company ultimately accomplish with Glowing Plants, not everyone shares their enthusiasm for the prospect of crowdsourced, home-grown, synthetic "genegeneering." Some question the project's safety, while others focus on its validity and financial ethics.

According to The New York Times, the environmental groups Friends of the Earth and the ETC Group have contacted U.S. Agriculture Department to head off the project and its potential "widespread, random and uncontrolled release of bioengineered seeds." As for the money, Evans told the Times that he will devote some Kickstarter funds to exploring related public policy issues, but many commenters remain skeptical [source: Pollack; Timmer].

So how scary are these trees? Could they pollute the environment with pixie pollen? It's hard to say. The process Glowing Plants will use resembles the one developed at Stony Brook University, which affected chloroplasts. In most flowering species, chloroplasts are maternally inherited -- passed on by seed, not pollen -- which reduces the risk of environmental contamination by, say, glowing roses, but many trees fall outside of this category [source: Krichevsky et al.].

And pollen poses only one of many potential environmental impact problems. For example, how would birds, squirrels or vital insects react to a glowing tree? How would planners go about conducting an environmental impact assessment for such a plant?

Meanwhile, numerous practical questions await answers as well: How much energy could such plants afford to allocate toward light production? And how brightly will they ultimately shine [sources: Pollack; Timmer]?

The problem is energy. Although the total solar radiation striking an average tree outstrips the amount required to power an effective streetlight, only a small fraction of that insolation reaches a tree's leaves -- and only a small portion of that falls within the wavelength band required for photosynthesis. The tree must then apply a sizable portion of this energy to living and growing, leaving only a fraction of a fraction of a fraction available to generate light -- to say nothing of the energy required to fabricate the necessary chemicals. The problem would only worsen in winter, when available sunlight dims and trees enter a metabolic stasis bound to kill their chemical shine [source: Timmer].

And that's the root of the problem. However poplar the idea might be, and however much donors might root or pine for it, glowing trees are a shady prospect at best.