[Xylakant]

> The pitch back then was to colonise space as plants would not need the sun for photosynthesis.

That's a stupid pitch. The light is required as an energy source for the photosynthesis. Making the plant glow would consume energy from the plant. If you could make a plant that glows without an outside energy source and use this light for photosynthesis while still being energy positive, you'd have broken a few fundamental laws of physics. Having these plants escape the lab and light up woods would be the least of my worries in that case.